Patchwork Move hook documentation from tm.texi.in to target.def

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Submitter Joseph S. Myers
Date July 10, 2013, 11:25 p.m.
Message ID <Pine.LNX.4.64.1307102324200.18288@digraph.polyomino.org.uk>
Download mbox | patch
Permalink /patch/258268/
State New
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Joseph S. Myers - July 10, 2013, 11:25 p.m.
This patch moves target hook documentation from tm.texi.in to its
preferred location in target.def along with the main definition of
each hook, leaving only the @hook line in tm.texi.in.  By design, it
makes no changes at all to the documentation itself - the generated
tm.texi file is unchanged.  It also does nothing about comments on
hooks in target.def that may now be redundant because they duplicate
the documentation string.  I'd certainly encourage followup cleanups
to remove such redundant comments or merge any useful comment contents
into the documentation strings.

As a reminder, if you want to move existing tm.texi.in text, or
comments from target.def or elsewhere, into hook docstrings in
target.def (for example, when converting a target macro to a target
hook), please ask one of the listed docstring relicensing maintainers
to review your patch.

Bootstrapped with no regressions on x86_64-unknown-linux-gnu.  Applied
to mainline.

2013-07-10  Joseph Myers  <joseph@codesourcery.com>

	* doc/tm.texi.in: Move hook documentation to ....
	* target.def: ... here.

Patch

Index: doc/tm.texi.in
===================================================================
--- doc/tm.texi.in	(revision 200891)
+++ doc/tm.texi.in	(working copy)
@@ -698,14 +698,6 @@ 
 @hook TARGET_CHECK_STRING_OBJECT_FORMAT_ARG
 
 @hook TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE
-This target function is similar to the hook @code{TARGET_OPTION_OVERRIDE}
-but is called when the optimize level is changed via an attribute or
-pragma or when it is reset at the end of the code affected by the
-attribute or pragma.  It is not called at the beginning of compilation
-when @code{TARGET_OPTION_OVERRIDE} is called so if you want to perform these
-actions then, you should have @code{TARGET_OPTION_OVERRIDE} call
-@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}.
-@end deftypefn
 
 @defmac C_COMMON_OVERRIDE_OPTIONS
 This is similar to the @code{TARGET_OPTION_OVERRIDE} hook
@@ -929,27 +921,7 @@ 
 @end defmac
 
 @hook TARGET_PROMOTE_FUNCTION_MODE
-Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or
-function return values.  The target hook should return the new mode
-and possibly change @code{*@var{punsignedp}} if the promotion should
-change signedness.  This function is called only for scalar @emph{or
-pointer} types.
 
-@var{for_return} allows to distinguish the promotion of arguments and
-return values.  If it is @code{1}, a return value is being promoted and
-@code{TARGET_FUNCTION_VALUE} must perform the same promotions done here.
-If it is @code{2}, the returned mode should be that of the register in
-which an incoming parameter is copied, or the outgoing result is computed;
-then the hook should return the same mode as @code{promote_mode}, though
-the signedness may be different.
-
-@var{type} can be NULL when promoting function arguments of libcalls.
-
-The default is to not promote arguments and return values.  You can
-also define the hook to @code{default_promote_function_mode_always_promote}
-if you would like to apply the same rules given by @code{PROMOTE_MODE}.
-@end deftypefn
-
 @defmac PARM_BOUNDARY
 Normal alignment required for function parameters on the stack, in
 bits.  All stack parameters receive at least this much alignment
@@ -1234,32 +1206,11 @@ 
 @end defmac
 
 @hook TARGET_ALIGN_ANON_BITFIELD
-When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine
-whether unnamed bitfields affect the alignment of the containing
-structure.  The hook should return true if the structure should inherit
-the alignment requirements of an unnamed bitfield's type.
-@end deftypefn
 
 @hook TARGET_NARROW_VOLATILE_BITFIELD
-This target hook should return @code{true} if accesses to volatile bitfields
-should use the narrowest mode possible.  It should return @code{false} if
-these accesses should use the bitfield container type.
 
-The default is @code{!TARGET_STRICT_ALIGN}.
-@end deftypefn
-
 @hook TARGET_MEMBER_TYPE_FORCES_BLK
-Return true if a structure, union or array containing @var{field} should
-be accessed using @code{BLKMODE}.
 
-If @var{field} is the only field in the structure, @var{mode} is its
-mode, otherwise @var{mode} is VOIDmode.  @var{mode} is provided in the
-case where structures of one field would require the structure's mode to
-retain the field's mode.
-
-Normally, this is not needed.
-@end deftypefn
-
 @defmac ROUND_TYPE_ALIGN (@var{type}, @var{computed}, @var{specified})
 Define this macro as an expression for the alignment of a type (given
 by @var{type} as a tree node) if the alignment computed in the usual
@@ -1303,23 +1254,10 @@ 
 @end defmac
 
 @hook TARGET_LIBGCC_CMP_RETURN_MODE
-This target hook should return the mode to be used for the return value
-of compare instructions expanded to libgcc calls.  If not defined
-@code{word_mode} is returned which is the right choice for a majority of
-targets.
-@end deftypefn
 
 @hook TARGET_LIBGCC_SHIFT_COUNT_MODE
-This target hook should return the mode to be used for the shift count operand
-of shift instructions expanded to libgcc calls.  If not defined
-@code{word_mode} is returned which is the right choice for a majority of
-targets.
-@end deftypefn
 
 @hook TARGET_UNWIND_WORD_MODE
-Return machine mode to be used for @code{_Unwind_Word} type.
-The default is to use @code{word_mode}.
-@end deftypefn
 
 @defmac ROUND_TOWARDS_ZERO
 If defined, this macro should be true if the prevailing rounding
@@ -1343,89 +1281,17 @@ 
 @end defmac
 
 @hook TARGET_MS_BITFIELD_LAYOUT_P
-This target hook returns @code{true} if bit-fields in the given
-@var{record_type} are to be laid out following the rules of Microsoft
-Visual C/C++, namely: (i) a bit-field won't share the same storage
-unit with the previous bit-field if their underlying types have
-different sizes, and the bit-field will be aligned to the highest
-alignment of the underlying types of itself and of the previous
-bit-field; (ii) a zero-sized bit-field will affect the alignment of
-the whole enclosing structure, even if it is unnamed; except that
-(iii) a zero-sized bit-field will be disregarded unless it follows
-another bit-field of nonzero size.  If this hook returns @code{true},
-other macros that control bit-field layout are ignored.
 
-When a bit-field is inserted into a packed record, the whole size
-of the underlying type is used by one or more same-size adjacent
-bit-fields (that is, if its long:3, 32 bits is used in the record,
-and any additional adjacent long bit-fields are packed into the same
-chunk of 32 bits.  However, if the size changes, a new field of that
-size is allocated).  In an unpacked record, this is the same as using
-alignment, but not equivalent when packing.
-
-If both MS bit-fields and @samp{__attribute__((packed))} are used,
-the latter will take precedence.  If @samp{__attribute__((packed))} is
-used on a single field when MS bit-fields are in use, it will take
-precedence for that field, but the alignment of the rest of the structure
-may affect its placement.
-@end deftypefn
-
 @hook TARGET_DECIMAL_FLOAT_SUPPORTED_P
-Returns true if the target supports decimal floating point.
-@end deftypefn
 
 @hook TARGET_FIXED_POINT_SUPPORTED_P
-Returns true if the target supports fixed-point arithmetic.
-@end deftypefn
 
 @hook TARGET_EXPAND_TO_RTL_HOOK
-This hook is called just before expansion into rtl, allowing the target
-to perform additional initializations or analysis before the expansion.
-For example, the rs6000 port uses it to allocate a scratch stack slot
-for use in copying SDmode values between memory and floating point
-registers whenever the function being expanded has any SDmode
-usage.
-@end deftypefn
 
 @hook TARGET_INSTANTIATE_DECLS
-This hook allows the backend to perform additional instantiations on rtl
-that are not actually in any insns yet, but will be later.
-@end deftypefn
 
 @hook TARGET_MANGLE_TYPE
-If your target defines any fundamental types, or any types your target
-uses should be mangled differently from the default, define this hook
-to return the appropriate encoding for these types as part of a C++
-mangled name.  The @var{type} argument is the tree structure representing
-the type to be mangled.  The hook may be applied to trees which are
-not target-specific fundamental types; it should return @code{NULL}
-for all such types, as well as arguments it does not recognize.  If the
-return value is not @code{NULL}, it must point to a statically-allocated
-string constant.
 
-Target-specific fundamental types might be new fundamental types or
-qualified versions of ordinary fundamental types.  Encode new
-fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name}
-is the name used for the type in source code, and @var{n} is the
-length of @var{name} in decimal.  Encode qualified versions of
-ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where
-@var{name} is the name used for the type qualifier in source code,
-@var{n} is the length of @var{name} as above, and @var{code} is the
-code used to represent the unqualified version of this type.  (See
-@code{write_builtin_type} in @file{cp/mangle.c} for the list of
-codes.)  In both cases the spaces are for clarity; do not include any
-spaces in your string.
-
-This hook is applied to types prior to typedef resolution.  If the mangled
-name for a particular type depends only on that type's main variant, you
-can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT}
-before mangling.
-
-The default version of this hook always returns @code{NULL}, which is
-appropriate for a target that does not define any new fundamental
-types.
-@end deftypefn
-
 @node Type Layout
 @section Layout of Source Language Data Types
 
@@ -1619,14 +1485,7 @@ 
 @end defmac
 
 @hook TARGET_DEFAULT_SHORT_ENUMS
-This target hook should return true if the compiler should give an
-@code{enum} type only as many bytes as it takes to represent the range
-of possible values of that type.  It should return false if all
-@code{enum} types should be allocated like @code{int}.
 
-The default is to return false.
-@end deftypefn
-
 @defmac SIZE_TYPE
 A C expression for a string describing the name of the data type to use
 for size values.  The typedef name @code{size_t} is defined using the
@@ -1921,37 +1780,7 @@ 
 @findex reg_names
 @findex reg_class_contents
 @hook TARGET_CONDITIONAL_REGISTER_USAGE
-This hook may conditionally modify five variables
-@code{fixed_regs}, @code{call_used_regs}, @code{global_regs},
-@code{reg_names}, and @code{reg_class_contents}, to take into account
-any dependence of these register sets on target flags.  The first three
-of these are of type @code{char []} (interpreted as Boolean vectors).
-@code{global_regs} is a @code{const char *[]}, and
-@code{reg_class_contents} is a @code{HARD_REG_SET}.  Before the macro is
-called, @code{fixed_regs}, @code{call_used_regs},
-@code{reg_class_contents}, and @code{reg_names} have been initialized
-from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS},
-@code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively.
-@code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}},
-@option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}
-command options have been applied.
 
-@cindex disabling certain registers
-@cindex controlling register usage
-If the usage of an entire class of registers depends on the target
-flags, you may indicate this to GCC by using this macro to modify
-@code{fixed_regs} and @code{call_used_regs} to 1 for each of the
-registers in the classes which should not be used by GCC@.  Also define
-the macro @code{REG_CLASS_FROM_LETTER} / @code{REG_CLASS_FROM_CONSTRAINT}
-to return @code{NO_REGS} if it
-is called with a letter for a class that shouldn't be used.
-
-(However, if this class is not included in @code{GENERAL_REGS} and all
-of the insn patterns whose constraints permit this class are
-controlled by target switches, then GCC will automatically avoid using
-these registers when the target switches are opposed to them.)
-@end deftypefn
-
 @defmac INCOMING_REGNO (@var{out})
 Define this macro if the target machine has register windows.  This C
 expression returns the register number as seen by the called function
@@ -2188,15 +2017,7 @@ 
 @end defmac
 
 @hook TARGET_HARD_REGNO_SCRATCH_OK
-This target hook should return @code{true} if it is OK to use a hard register
-@var{regno} as scratch reg in peephole2.
 
-One common use of this macro is to prevent using of a register that
-is not saved by a prologue in an interrupt handler.
-
-The default version of this hook always returns @code{true}.
-@end deftypefn
-
 @defmac AVOID_CCMODE_COPIES
 Define this macro if the compiler should avoid copies to/from @code{CCmode}
 registers.  You should only define this macro if support for copying to/from
@@ -2523,39 +2344,7 @@ 
 @hook TARGET_PREFERRED_RENAME_CLASS
 
 @hook TARGET_PREFERRED_RELOAD_CLASS
-A target hook that places additional restrictions on the register class
-to use when it is necessary to copy value @var{x} into a register in class
-@var{rclass}.  The value is a register class; perhaps @var{rclass}, or perhaps
-another, smaller class.
 
-The default version of this hook always returns value of @code{rclass} argument.
-
-Sometimes returning a more restrictive class makes better code.  For
-example, on the 68000, when @var{x} is an integer constant that is in range
-for a @samp{moveq} instruction, the value of this macro is always
-@code{DATA_REGS} as long as @var{rclass} includes the data registers.
-Requiring a data register guarantees that a @samp{moveq} will be used.
-
-One case where @code{TARGET_PREFERRED_RELOAD_CLASS} must not return
-@var{rclass} is if @var{x} is a legitimate constant which cannot be
-loaded into some register class.  By returning @code{NO_REGS} you can
-force @var{x} into a memory location.  For example, rs6000 can load
-immediate values into general-purpose registers, but does not have an
-instruction for loading an immediate value into a floating-point
-register, so @code{TARGET_PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when
-@var{x} is a floating-point constant.  If the constant can't be loaded
-into any kind of register, code generation will be better if
-@code{TARGET_LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead
-of using @code{TARGET_PREFERRED_RELOAD_CLASS}.
-
-If an insn has pseudos in it after register allocation, reload will go
-through the alternatives and call repeatedly @code{TARGET_PREFERRED_RELOAD_CLASS}
-to find the best one.  Returning @code{NO_REGS}, in this case, makes
-reload add a @code{!} in front of the constraint: the x86 back-end uses
-this feature to discourage usage of 387 registers when math is done in
-the SSE registers (and vice versa).
-@end deftypefn
-
 @defmac PREFERRED_RELOAD_CLASS (@var{x}, @var{class})
 A C expression that places additional restrictions on the register class
 to use when it is necessary to copy value @var{x} into a register in class
@@ -2594,16 +2383,7 @@ 
 @end defmac
 
 @hook TARGET_PREFERRED_OUTPUT_RELOAD_CLASS
-Like @code{TARGET_PREFERRED_RELOAD_CLASS}, but for output reloads instead of
-input reloads.
 
-The default version of this hook always returns value of @code{rclass}
-argument.
-
-You can also use @code{TARGET_PREFERRED_OUTPUT_RELOAD_CLASS} to discourage
-reload from using some alternatives, like @code{TARGET_PREFERRED_RELOAD_CLASS}.
-@end deftypefn
-
 @defmac LIMIT_RELOAD_CLASS (@var{mode}, @var{class})
 A C expression that places additional restrictions on the register class
 to use when it is necessary to be able to hold a value of mode
@@ -2621,91 +2401,7 @@ 
 @end defmac
 
 @hook TARGET_SECONDARY_RELOAD
-Many machines have some registers that cannot be copied directly to or
-from memory or even from other types of registers.  An example is the
-@samp{MQ} register, which on most machines, can only be copied to or
-from general registers, but not memory.  Below, we shall be using the
-term 'intermediate register' when a move operation cannot be performed
-directly, but has to be done by copying the source into the intermediate
-register first, and then copying the intermediate register to the
-destination.  An intermediate register always has the same mode as
-source and destination.  Since it holds the actual value being copied,
-reload might apply optimizations to re-use an intermediate register
-and eliding the copy from the source when it can determine that the
-intermediate register still holds the required value.
 
-Another kind of secondary reload is required on some machines which
-allow copying all registers to and from memory, but require a scratch
-register for stores to some memory locations (e.g., those with symbolic
-address on the RT, and those with certain symbolic address on the SPARC
-when compiling PIC)@.  Scratch registers need not have the same mode
-as the value being copied, and usually hold a different value than
-that being copied.  Special patterns in the md file are needed to
-describe how the copy is performed with the help of the scratch register;
-these patterns also describe the number, register class(es) and mode(s)
-of the scratch register(s).
-
-In some cases, both an intermediate and a scratch register are required.
-
-For input reloads, this target hook is called with nonzero @var{in_p},
-and @var{x} is an rtx that needs to be copied to a register of class
-@var{reload_class} in @var{reload_mode}.  For output reloads, this target
-hook is called with zero @var{in_p}, and a register of class @var{reload_class}
-needs to be copied to rtx @var{x} in @var{reload_mode}.
-
-If copying a register of @var{reload_class} from/to @var{x} requires
-an intermediate register, the hook @code{secondary_reload} should
-return the register class required for this intermediate register.
-If no intermediate register is required, it should return NO_REGS.
-If more than one intermediate register is required, describe the one
-that is closest in the copy chain to the reload register.
-
-If scratch registers are needed, you also have to describe how to
-perform the copy from/to the reload register to/from this
-closest intermediate register.  Or if no intermediate register is
-required, but still a scratch register is needed, describe the
-copy  from/to the reload register to/from the reload operand @var{x}.
-
-You do this by setting @code{sri->icode} to the instruction code of a pattern
-in the md file which performs the move.  Operands 0 and 1 are the output
-and input of this copy, respectively.  Operands from operand 2 onward are
-for scratch operands.  These scratch operands must have a mode, and a
-single-register-class
-@c [later: or memory]
-output constraint.
-
-When an intermediate register is used, the @code{secondary_reload}
-hook will be called again to determine how to copy the intermediate
-register to/from the reload operand @var{x}, so your hook must also
-have code to handle the register class of the intermediate operand.
-
-@c [For later: maybe we'll allow multi-alternative reload patterns -
-@c   the port maintainer could name a mov<mode> pattern that has clobbers -
-@c   and match the constraints of input and output to determine the required
-@c   alternative.  A restriction would be that constraints used to match
-@c   against reloads registers would have to be written as register class
-@c   constraints, or we need a new target macro / hook that tells us if an
-@c   arbitrary constraint can match an unknown register of a given class.
-@c   Such a macro / hook would also be useful in other places.]
-
-
-@var{x} might be a pseudo-register or a @code{subreg} of a
-pseudo-register, which could either be in a hard register or in memory.
-Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is
-in memory and the hard register number if it is in a register.
-
-Scratch operands in memory (constraint @code{"=m"} / @code{"=&m"}) are
-currently not supported.  For the time being, you will have to continue
-to use @code{SECONDARY_MEMORY_NEEDED} for that purpose.
-
-@code{copy_cost} also uses this target hook to find out how values are
-copied.  If you want it to include some extra cost for the need to allocate
-(a) scratch register(s), set @code{sri->extra_cost} to the additional cost.
-Or if two dependent moves are supposed to have a lower cost than the sum
-of the individual moves due to expected fortuitous scheduling and/or special
-forwarding logic, you can set @code{sri->extra_cost} to a negative amount.
-@end deftypefn
-
 @defmac SECONDARY_RELOAD_CLASS (@var{class}, @var{mode}, @var{x})
 @defmacx SECONDARY_INPUT_RELOAD_CLASS (@var{class}, @var{mode}, @var{x})
 @defmacx SECONDARY_OUTPUT_RELOAD_CLASS (@var{class}, @var{mode}, @var{x})
@@ -2812,38 +2508,9 @@ 
 @end defmac
 
 @hook TARGET_CLASS_LIKELY_SPILLED_P
-A target hook which returns @code{true} if pseudos that have been assigned
-to registers of class @var{rclass} would likely be spilled because
-registers of @var{rclass} are needed for spill registers.
 
-The default version of this target hook returns @code{true} if @var{rclass}
-has exactly one register and @code{false} otherwise.  On most machines, this
-default should be used.  For generally register-starved machines, such as
-i386, or machines with right register constraints, such as SH, this hook
-can be used to avoid excessive spilling.
-
-This hook is also used by some of the global intra-procedural code
-transformations to throtle code motion, to avoid increasing register
-pressure.
-@end deftypefn
-
 @hook TARGET_CLASS_MAX_NREGS
-A target hook returns the maximum number of consecutive registers
-of class @var{rclass} needed to hold a value of mode @var{mode}.
 
-This is closely related to the macro @code{HARD_REGNO_NREGS}.  In fact,
-the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass},
-@var{mode})} target hook should be the maximum value of
-@code{HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno}
-values in the class @var{rclass}.
-
-This target hook helps control the handling of multiple-word values
-in the reload pass.
-
-The default version of this target hook returns the size of @var{mode}
-in words.
-@end deftypefn
-
 @defmac CLASS_MAX_NREGS (@var{class}, @var{mode})
 A C expression for the maximum number of consecutive registers
 of class @var{class} needed to hold a value of mode @var{mode}.
@@ -3178,12 +2845,6 @@ 
 @end defmac
 
 @hook TARGET_BUILTIN_SETJMP_FRAME_VALUE
-This target hook should return an rtx that is used to store
-the address of the current frame into the built in @code{setjmp} buffer.
-The default value, @code{virtual_stack_vars_rtx}, is correct for most
-machines.  One reason you may need to define this target hook is if
-@code{hard_frame_pointer_rtx} is the appropriate value on your machine.
-@end deftypefn
 
 @defmac FRAME_ADDR_RTX (@var{frameaddr})
 A C expression whose value is RTL representing the value of the frame
@@ -3245,20 +2906,6 @@ 
 @end defmac
 
 @hook TARGET_DWARF_HANDLE_FRAME_UNSPEC
-This target hook allows the backend to emit frame-related insns that
-contain UNSPECs or UNSPEC_VOLATILEs.  The DWARF 2 call frame debugging
-info engine will invoke it on insns of the form
-@smallexample
-(set (reg) (unspec [@dots{}] UNSPEC_INDEX))
-@end smallexample
-and
-@smallexample
-(set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)).
-@end smallexample
-to let the backend emit the call frame instructions.  @var{label} is
-the CFI label attached to the insn, @var{pattern} is the pattern of
-the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}.
-@end deftypefn
 
 @defmac INCOMING_FRAME_SP_OFFSET
 A C expression whose value is an integer giving the offset, in bytes,
@@ -3641,27 +3288,7 @@ 
 @end defmac
 
 @hook TARGET_STATIC_CHAIN
-This hook replaces the use of @code{STATIC_CHAIN_REGNUM} et al for
-targets that may use different static chain locations for different
-nested functions.  This may be required if the target has function
-attributes that affect the calling conventions of the function and
-those calling conventions use different static chain locations.
 
-The default version of this hook uses @code{STATIC_CHAIN_REGNUM} et al.
-
-If the static chain is passed in memory, this hook should be used to
-provide rtx giving @code{mem} expressions that denote where they are stored.
-Often the @code{mem} expression as seen by the caller will be at an offset
-from the stack pointer and the @code{mem} expression as seen by the callee
-will be at an offset from the frame pointer.
-@findex stack_pointer_rtx
-@findex frame_pointer_rtx
-@findex arg_pointer_rtx
-The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and
-@code{arg_pointer_rtx} will have been initialized and should be used
-to refer to those items.
-@end deftypefn
-
 @defmac DWARF_FRAME_REGISTERS
 This macro specifies the maximum number of hard registers that can be
 saved in a call frame.  This is used to size data structures used in
@@ -3743,30 +3370,7 @@ 
 This is about eliminating the frame pointer and arg pointer.
 
 @hook TARGET_FRAME_POINTER_REQUIRED
-This target hook should return @code{true} if a function must have and use
-a frame pointer.  This target hook is called in the reload pass.  If its return
-value is @code{true} the function will have a frame pointer.
 
-This target hook can in principle examine the current function and decide
-according to the facts, but on most machines the constant @code{false} or the
-constant @code{true} suffices.  Use @code{false} when the machine allows code
-to be generated with no frame pointer, and doing so saves some time or space.
-Use @code{true} when there is no possible advantage to avoiding a frame
-pointer.
-
-In certain cases, the compiler does not know how to produce valid code
-without a frame pointer.  The compiler recognizes those cases and
-automatically gives the function a frame pointer regardless of what
-@code{TARGET_FRAME_POINTER_REQUIRED} returns.  You don't need to worry about
-them.
-
-In a function that does not require a frame pointer, the frame pointer
-register can be allocated for ordinary usage, unless you mark it as a
-fixed register.  See @code{FIXED_REGISTERS} for more information.
-
-Default return value is @code{false}.
-@end deftypefn
-
 @findex get_frame_size
 @defmac INITIAL_FRAME_POINTER_OFFSET (@var{depth-var})
 A C statement to store in the variable @var{depth-var} the difference
@@ -3809,16 +3413,7 @@ 
 @end defmac
 
 @hook TARGET_CAN_ELIMINATE
-This target hook should returns @code{true} if the compiler is allowed to
-try to replace register number @var{from_reg} with register number
-@var{to_reg}.  This target hook need only be defined if @code{ELIMINABLE_REGS}
-is defined, and will usually be @code{true}, since most of the cases
-preventing register elimination are things that the compiler already
-knows about.
 
-Default return value is @code{true}.
-@end deftypefn
-
 @defmac INITIAL_ELIMINATION_OFFSET (@var{from-reg}, @var{to-reg}, @var{offset-var})
 This macro is similar to @code{INITIAL_FRAME_POINTER_OFFSET}.  It
 specifies the initial difference between the specified pair of
@@ -3836,12 +3431,6 @@ 
 control passing certain arguments in registers.
 
 @hook TARGET_PROMOTE_PROTOTYPES
-This target hook returns @code{true} if an argument declared in a
-prototype as an integral type smaller than @code{int} should actually be
-passed as an @code{int}.  In addition to avoiding errors in certain
-cases of mismatch, it also makes for better code on certain machines.
-The default is to not promote prototypes.
-@end deftypefn
 
 @defmac PUSH_ARGS
 A C expression.  If nonzero, push insns will be used to pass
@@ -3936,43 +3525,7 @@ 
 @end defmac
 
 @hook TARGET_RETURN_POPS_ARGS
-This target hook returns the number of bytes of its own arguments that
-a function pops on returning, or 0 if the function pops no arguments
-and the caller must therefore pop them all after the function returns.
 
-@var{fundecl} is a C variable whose value is a tree node that describes
-the function in question.  Normally it is a node of type
-@code{FUNCTION_DECL} that describes the declaration of the function.
-From this you can obtain the @code{DECL_ATTRIBUTES} of the function.
-
-@var{funtype} is a C variable whose value is a tree node that
-describes the function in question.  Normally it is a node of type
-@code{FUNCTION_TYPE} that describes the data type of the function.
-From this it is possible to obtain the data types of the value and
-arguments (if known).
-
-When a call to a library function is being considered, @var{fundecl}
-will contain an identifier node for the library function.  Thus, if
-you need to distinguish among various library functions, you can do so
-by their names.  Note that ``library function'' in this context means
-a function used to perform arithmetic, whose name is known specially
-in the compiler and was not mentioned in the C code being compiled.
-
-@var{size} is the number of bytes of arguments passed on the
-stack.  If a variable number of bytes is passed, it is zero, and
-argument popping will always be the responsibility of the calling function.
-
-On the VAX, all functions always pop their arguments, so the definition
-of this macro is @var{size}.  On the 68000, using the standard
-calling convention, no functions pop their arguments, so the value of
-the macro is always 0 in this case.  But an alternative calling
-convention is available in which functions that take a fixed number of
-arguments pop them but other functions (such as @code{printf}) pop
-nothing (the caller pops all).  When this convention is in use,
-@var{funtype} is examined to determine whether a function takes a fixed
-number of arguments.
-@end deftypefn
-
 @defmac CALL_POPS_ARGS (@var{cum})
 A C expression that should indicate the number of bytes a call sequence
 pops off the stack.  It is added to the value of @code{RETURN_POPS_ARGS}
@@ -3998,125 +3551,17 @@ 
 the stack.
 
 @hook TARGET_FUNCTION_ARG
-Return an RTX indicating whether a function argument is passed in a
-register and if so, which register.
 
-The arguments are @var{ca}, which summarizes all the previous
-arguments; @var{mode}, the machine mode of the argument; @var{type},
-the data type of the argument as a tree node or 0 if that is not known
-(which happens for C support library functions); and @var{named},
-which is @code{true} for an ordinary argument and @code{false} for
-nameless arguments that correspond to @samp{@dots{}} in the called
-function's prototype.  @var{type} can be an incomplete type if a
-syntax error has previously occurred.
-
-The return value is usually either a @code{reg} RTX for the hard
-register in which to pass the argument, or zero to pass the argument
-on the stack.
-
-The value of the expression can also be a @code{parallel} RTX@.  This is
-used when an argument is passed in multiple locations.  The mode of the
-@code{parallel} should be the mode of the entire argument.  The
-@code{parallel} holds any number of @code{expr_list} pairs; each one
-describes where part of the argument is passed.  In each
-@code{expr_list} the first operand must be a @code{reg} RTX for the hard
-register in which to pass this part of the argument, and the mode of the
-register RTX indicates how large this part of the argument is.  The
-second operand of the @code{expr_list} is a @code{const_int} which gives
-the offset in bytes into the entire argument of where this part starts.
-As a special exception the first @code{expr_list} in the @code{parallel}
-RTX may have a first operand of zero.  This indicates that the entire
-argument is also stored on the stack.
-
-The last time this hook is called, it is called with @code{MODE ==
-VOIDmode}, and its result is passed to the @code{call} or @code{call_value}
-pattern as operands 2 and 3 respectively.
-
-@cindex @file{stdarg.h} and register arguments
-The usual way to make the ISO library @file{stdarg.h} work on a
-machine where some arguments are usually passed in registers, is to
-cause nameless arguments to be passed on the stack instead.  This is
-done by making @code{TARGET_FUNCTION_ARG} return 0 whenever
-@var{named} is @code{false}.
-
-@cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{TARGET_FUNCTION_ARG}
-@cindex @code{REG_PARM_STACK_SPACE}, and @code{TARGET_FUNCTION_ARG}
-You may use the hook @code{targetm.calls.must_pass_in_stack}
-in the definition of this macro to determine if this argument is of a
-type that must be passed in the stack.  If @code{REG_PARM_STACK_SPACE}
-is not defined and @code{TARGET_FUNCTION_ARG} returns nonzero for such an
-argument, the compiler will abort.  If @code{REG_PARM_STACK_SPACE} is
-defined, the argument will be computed in the stack and then loaded into
-a register.
-@end deftypefn
-
 @hook TARGET_MUST_PASS_IN_STACK
-This target hook should return @code{true} if we should not pass @var{type}
-solely in registers.  The file @file{expr.h} defines a
-definition that is usually appropriate, refer to @file{expr.h} for additional
-documentation.
-@end deftypefn
 
 @hook TARGET_FUNCTION_INCOMING_ARG
-Define this hook if the target machine has ``register windows'', so
-that the register in which a function sees an arguments is not
-necessarily the same as the one in which the caller passed the
-argument.
 
-For such machines, @code{TARGET_FUNCTION_ARG} computes the register in
-which the caller passes the value, and
-@code{TARGET_FUNCTION_INCOMING_ARG} should be defined in a similar
-fashion to tell the function being called where the arguments will
-arrive.
-
-If @code{TARGET_FUNCTION_INCOMING_ARG} is not defined,
-@code{TARGET_FUNCTION_ARG} serves both purposes.
-@end deftypefn
-
 @hook TARGET_ARG_PARTIAL_BYTES
-This target hook returns the number of bytes at the beginning of an
-argument that must be put in registers.  The value must be zero for
-arguments that are passed entirely in registers or that are entirely
-pushed on the stack.
 
-On some machines, certain arguments must be passed partially in
-registers and partially in memory.  On these machines, typically the
-first few words of arguments are passed in registers, and the rest
-on the stack.  If a multi-word argument (a @code{double} or a
-structure) crosses that boundary, its first few words must be passed
-in registers and the rest must be pushed.  This macro tells the
-compiler when this occurs, and how many bytes should go in registers.
-
-@code{TARGET_FUNCTION_ARG} for these arguments should return the first
-register to be used by the caller for this argument; likewise
-@code{TARGET_FUNCTION_INCOMING_ARG}, for the called function.
-@end deftypefn
-
 @hook TARGET_PASS_BY_REFERENCE
-This target hook should return @code{true} if an argument at the
-position indicated by @var{cum} should be passed by reference.  This
-predicate is queried after target independent reasons for being
-passed by reference, such as @code{TREE_ADDRESSABLE (type)}.
 
-If the hook returns true, a copy of that argument is made in memory and a
-pointer to the argument is passed instead of the argument itself.
-The pointer is passed in whatever way is appropriate for passing a pointer
-to that type.
-@end deftypefn
-
 @hook TARGET_CALLEE_COPIES
-The function argument described by the parameters to this hook is
-known to be passed by reference.  The hook should return true if the
-function argument should be copied by the callee instead of copied
-by the caller.
 
-For any argument for which the hook returns true, if it can be
-determined that the argument is not modified, then a copy need
-not be generated.
-
-The default version of this hook always returns false.
-@end deftypefn
-
 @defmac CUMULATIVE_ARGS
 A C type for declaring a variable that is used as the first argument
 of @code{TARGET_FUNCTION_ARG} and other related values.  For some
@@ -4184,17 +3629,7 @@ 
 @end defmac
 
 @hook TARGET_FUNCTION_ARG_ADVANCE
-This hook updates the summarizer variable pointed to by @var{ca} to
-advance past an argument in the argument list.  The values @var{mode},
-@var{type} and @var{named} describe that argument.  Once this is done,
-the variable @var{cum} is suitable for analyzing the @emph{following}
-argument with @code{TARGET_FUNCTION_ARG}, etc.
 
-This hook need not do anything if the argument in question was passed
-on the stack.  The compiler knows how to track the amount of stack space
-used for arguments without any special help.
-@end deftypefn
-
 @defmac FUNCTION_ARG_OFFSET (@var{mode}, @var{type})
 If defined, a C expression that is the number of bytes to add to the
 offset of the argument passed in memory.  This is needed for the SPU,
@@ -4239,10 +3674,6 @@ 
 @end defmac
 
 @hook TARGET_FUNCTION_ARG_BOUNDARY
-This hook returns the alignment boundary, in bits, of an argument
-with the specified mode and type.  The default hook returns
-@code{PARM_BOUNDARY} for all arguments.
-@end deftypefn
 
 @hook TARGET_FUNCTION_ARG_ROUND_BOUNDARY
 
@@ -4256,116 +3687,29 @@ 
 @end defmac
 
 @hook TARGET_SPLIT_COMPLEX_ARG
-This hook should return true if parameter of type @var{type} are passed
-as two scalar parameters.  By default, GCC will attempt to pack complex
-arguments into the target's word size.  Some ABIs require complex arguments
-to be split and treated as their individual components.  For example, on
-AIX64, complex floats should be passed in a pair of floating point
-registers, even though a complex float would fit in one 64-bit floating
-point register.
 
-The default value of this hook is @code{NULL}, which is treated as always
-false.
-@end deftypefn
-
 @hook TARGET_BUILD_BUILTIN_VA_LIST
-This hook returns a type node for @code{va_list} for the target.
-The default version of the hook returns @code{void*}.
-@end deftypefn
 
 @hook TARGET_ENUM_VA_LIST_P
-This target hook is used in function @code{c_common_nodes_and_builtins}
-to iterate through the target specific builtin types for va_list. The
-variable @var{idx} is used as iterator. @var{pname} has to be a pointer
-to a @code{const char *} and @var{ptree} a pointer to a @code{tree} typed
-variable.
-The arguments @var{pname} and @var{ptree} are used to store the result of
-this macro and are set to the name of the va_list builtin type and its
-internal type.
-If the return value of this macro is zero, then there is no more element.
-Otherwise the @var{IDX} should be increased for the next call of this
-macro to iterate through all types.
-@end deftypefn
 
 @hook TARGET_FN_ABI_VA_LIST
-This hook returns the va_list type of the calling convention specified by
-@var{fndecl}.
-The default version of this hook returns @code{va_list_type_node}.
-@end deftypefn
 
 @hook TARGET_CANONICAL_VA_LIST_TYPE
-This hook returns the va_list type of the calling convention specified by the
-type of @var{type}. If @var{type} is not a valid va_list type, it returns
-@code{NULL_TREE}.
-@end deftypefn
 
 @hook TARGET_GIMPLIFY_VA_ARG_EXPR
-This hook performs target-specific gimplification of
-@code{VA_ARG_EXPR}.  The first two parameters correspond to the
-arguments to @code{va_arg}; the latter two are as in
-@code{gimplify.c:gimplify_expr}.
-@end deftypefn
 
 @hook TARGET_VALID_POINTER_MODE
-Define this to return nonzero if the port can handle pointers
-with machine mode @var{mode}.  The default version of this
-hook returns true for both @code{ptr_mode} and @code{Pmode}.
-@end deftypefn
 
 @hook TARGET_REF_MAY_ALIAS_ERRNO
 
 @hook TARGET_SCALAR_MODE_SUPPORTED_P
-Define this to return nonzero if the port is prepared to handle
-insns involving scalar mode @var{mode}.  For a scalar mode to be
-considered supported, all the basic arithmetic and comparisons
-must work.
 
-The default version of this hook returns true for any mode
-required to handle the basic C types (as defined by the port).
-Included here are the double-word arithmetic supported by the
-code in @file{optabs.c}.
-@end deftypefn
-
 @hook TARGET_VECTOR_MODE_SUPPORTED_P
-Define this to return nonzero if the port is prepared to handle
-insns involving vector mode @var{mode}.  At the very least, it
-must have move patterns for this mode.
-@end deftypefn
 
 @hook TARGET_ARRAY_MODE_SUPPORTED_P
 
 @hook TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P
-Define this to return nonzero for machine modes for which the port has
-small register classes.  If this target hook returns nonzero for a given
-@var{mode}, the compiler will try to minimize the lifetime of registers
-in @var{mode}.  The hook may be called with @code{VOIDmode} as argument.
-In this case, the hook is expected to return nonzero if it returns nonzero
-for any mode.
 
-On some machines, it is risky to let hard registers live across arbitrary
-insns.  Typically, these machines have instructions that require values
-to be in specific registers (like an accumulator), and reload will fail
-if the required hard register is used for another purpose across such an
-insn.
-
-Passes before reload do not know which hard registers will be used
-in an instruction, but the machine modes of the registers set or used in
-the instruction are already known.  And for some machines, register
-classes are small for, say, integer registers but not for floating point
-registers.  For example, the AMD x86-64 architecture requires specific
-registers for the legacy x86 integer instructions, but there are many
-SSE registers for floating point operations.  On such targets, a good
-strategy may be to return nonzero from this hook for @code{INTEGRAL_MODE_P}
-machine modes but zero for the SSE register classes.
-
-The default version of this hook returns false for any mode.  It is always
-safe to redefine this hook to return with a nonzero value.  But if you
-unnecessarily define it, you will reduce the amount of optimizations
-that can be performed in some cases.  If you do not define this hook
-to return a nonzero value when it is required, the compiler will run out
-of spill registers and print a fatal error message.
-@end deftypefn
-
 @hook TARGET_FLAGS_REGNUM
 
 @node Scalar Return
@@ -4379,48 +3723,6 @@ 
 
 @hook TARGET_FUNCTION_VALUE
 
-Define this to return an RTX representing the place where a function
-returns or receives a value of data type @var{ret_type}, a tree node
-representing a data type.  @var{fn_decl_or_type} is a tree node
-representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a
-function being called.  If @var{outgoing} is false, the hook should
-compute the register in which the caller will see the return value.
-Otherwise, the hook should return an RTX representing the place where
-a function returns a value.
-
-On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant.
-(Actually, on most machines, scalar values are returned in the same
-place regardless of mode.)  The value of the expression is usually a
-@code{reg} RTX for the hard register where the return value is stored.
-The value can also be a @code{parallel} RTX, if the return value is in
-multiple places.  See @code{TARGET_FUNCTION_ARG} for an explanation of the
-@code{parallel} form.   Note that the callee will populate every
-location specified in the @code{parallel}, but if the first element of
-the @code{parallel} contains the whole return value, callers will use
-that element as the canonical location and ignore the others.  The m68k
-port uses this type of @code{parallel} to return pointers in both
-@samp{%a0} (the canonical location) and @samp{%d0}.
-
-If @code{TARGET_PROMOTE_FUNCTION_RETURN} returns true, you must apply
-the same promotion rules specified in @code{PROMOTE_MODE} if
-@var{valtype} is a scalar type.
-
-If the precise function being called is known, @var{func} is a tree
-node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null
-pointer.  This makes it possible to use a different value-returning
-convention for specific functions when all their calls are
-known.
-
-Some target machines have ``register windows'' so that the register in
-which a function returns its value is not the same as the one in which
-the caller sees the value.  For such machines, you should return
-different RTX depending on @var{outgoing}.
-
-@code{TARGET_FUNCTION_VALUE} is not used for return values with
-aggregate data types, because these are returned in another way.  See
-@code{TARGET_STRUCT_VALUE_RTX} and related macros, below.
-@end deftypefn
-
 @defmac FUNCTION_VALUE (@var{valtype}, @var{func})
 This macro has been deprecated.  Use @code{TARGET_FUNCTION_VALUE} for
 a new target instead.
@@ -4437,16 +3739,7 @@ 
 @end defmac
 
 @hook TARGET_LIBCALL_VALUE
-Define this hook if the back-end needs to know the name of the libcall
-function in order to determine where the result should be returned.
 
-The mode of the result is given by @var{mode} and the name of the called
-library function is given by @var{fun}.  The hook should return an RTX
-representing the place where the library function result will be returned.
-
-If this hook is not defined, then LIBCALL_VALUE will be used.
-@end deftypefn
-
 @defmac FUNCTION_VALUE_REGNO_P (@var{regno})
 A C expression that is nonzero if @var{regno} is the number of a hard
 register in which the values of called function may come back.
@@ -4469,20 +3762,7 @@ 
 @end defmac
 
 @hook TARGET_FUNCTION_VALUE_REGNO_P
-A target hook that return @code{true} if @var{regno} is the number of a hard
-register in which the values of called function may come back.
 
-A register whose use for returning values is limited to serving as the
-second of a pair (for a value of type @code{double}, say) need not be
-recognized by this target hook.
-
-If the machine has register windows, so that the caller and the called
-function use different registers for the return value, this target hook
-should recognize only the caller's register numbers.
-
-If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
-@end deftypefn
-
 @defmac APPLY_RESULT_SIZE
 Define this macro if @samp{untyped_call} and @samp{untyped_return}
 need more space than is implied by @code{FUNCTION_VALUE_REGNO_P} for
@@ -4490,18 +3770,7 @@ 
 @end defmac
 
 @hook TARGET_RETURN_IN_MSB
-This hook should return true if values of type @var{type} are returned
-at the most significant end of a register (in other words, if they are
-padded at the least significant end).  You can assume that @var{type}
-is returned in a register; the caller is required to check this.
 
-Note that the register provided by @code{TARGET_FUNCTION_VALUE} must
-be able to hold the complete return value.  For example, if a 1-, 2-
-or 3-byte structure is returned at the most significant end of a
-4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an
-@code{SImode} rtx.
-@end deftypefn
-
 @node Aggregate Return
 @subsection How Large Values Are Returned
 @cindex aggregates as return values
@@ -4520,24 +3789,7 @@ 
 memory.
 
 @hook TARGET_RETURN_IN_MEMORY
-This target hook should return a nonzero value to say to return the
-function value in memory, just as large structures are always returned.
-Here @var{type} will be the data type of the value, and @var{fntype}
-will be the type of the function doing the returning, or @code{NULL} for
-libcalls.
 
-Note that values of mode @code{BLKmode} must be explicitly handled
-by this function.  Also, the option @option{-fpcc-struct-return}
-takes effect regardless of this macro.  On most systems, it is
-possible to leave the hook undefined; this causes a default
-definition to be used, whose value is the constant 1 for @code{BLKmode}
-values, and 0 otherwise.
-
-Do not use this hook to indicate that structures and unions should always
-be returned in memory.  You should instead use @code{DEFAULT_PCC_STRUCT_RETURN}
-to indicate this.
-@end deftypefn
-
 @defmac DEFAULT_PCC_STRUCT_RETURN
 Define this macro to be 1 if all structure and union return values must be
 in memory.  Since this results in slower code, this should be defined
@@ -4550,28 +3802,7 @@ 
 @end defmac
 
 @hook TARGET_STRUCT_VALUE_RTX
-This target hook should return the location of the structure value
-address (normally a @code{mem} or @code{reg}), or 0 if the address is
-passed as an ``invisible'' first argument.  Note that @var{fndecl} may
-be @code{NULL}, for libcalls.  You do not need to define this target
-hook if the address is always passed as an ``invisible'' first
-argument.
 
-On some architectures the place where the structure value address
-is found by the called function is not the same place that the
-caller put it.  This can be due to register windows, or it could
-be because the function prologue moves it to a different place.
-@var{incoming} is @code{1} or @code{2} when the location is needed in
-the context of the called function, and @code{0} in the context of
-the caller.
-
-If @var{incoming} is nonzero and the address is to be found on the
-stack, return a @code{mem} which refers to the frame pointer. If
-@var{incoming} is @code{2}, the result is being used to fetch the
-structure value address at the beginning of a function.  If you need
-to emit adjusting code, you should do it at this point.
-@end deftypefn
-
 @defmac PCC_STATIC_STRUCT_RETURN
 Define this macro if the usual system convention on the target machine
 for returning structures and unions is for the called function to return
@@ -4623,111 +3854,13 @@ 
 (@dfn{prologue}) and exit (@dfn{epilogue}) code.
 
 @hook TARGET_ASM_FUNCTION_PROLOGUE
-If defined, a function that outputs the assembler code for entry to a
-function.  The prologue is responsible for setting up the stack frame,
-initializing the frame pointer register, saving registers that must be
-saved, and allocating @var{size} additional bytes of storage for the
-local variables.  @var{size} is an integer.  @var{file} is a stdio
-stream to which the assembler code should be output.
 
-The label for the beginning of the function need not be output by this
-macro.  That has already been done when the macro is run.
-
-@findex regs_ever_live
-To determine which registers to save, the macro can refer to the array
-@code{regs_ever_live}: element @var{r} is nonzero if hard register
-@var{r} is used anywhere within the function.  This implies the function
-prologue should save register @var{r}, provided it is not one of the
-call-used registers.  (@code{TARGET_ASM_FUNCTION_EPILOGUE} must likewise use
-@code{regs_ever_live}.)
-
-On machines that have ``register windows'', the function entry code does
-not save on the stack the registers that are in the windows, even if
-they are supposed to be preserved by function calls; instead it takes
-appropriate steps to ``push'' the register stack, if any non-call-used
-registers are used in the function.
-
-@findex frame_pointer_needed
-On machines where functions may or may not have frame-pointers, the
-function entry code must vary accordingly; it must set up the frame
-pointer if one is wanted, and not otherwise.  To determine whether a
-frame pointer is in wanted, the macro can refer to the variable
-@code{frame_pointer_needed}.  The variable's value will be 1 at run
-time in a function that needs a frame pointer.  @xref{Elimination}.
-
-The function entry code is responsible for allocating any stack space
-required for the function.  This stack space consists of the regions
-listed below.  In most cases, these regions are allocated in the
-order listed, with the last listed region closest to the top of the
-stack (the lowest address if @code{STACK_GROWS_DOWNWARD} is defined, and
-the highest address if it is not defined).  You can use a different order
-for a machine if doing so is more convenient or required for
-compatibility reasons.  Except in cases where required by standard
-or by a debugger, there is no reason why the stack layout used by GCC
-need agree with that used by other compilers for a machine.
-@end deftypefn
-
 @hook TARGET_ASM_FUNCTION_END_PROLOGUE
-If defined, a function that outputs assembler code at the end of a
-prologue.  This should be used when the function prologue is being
-emitted as RTL, and you have some extra assembler that needs to be
-emitted.  @xref{prologue instruction pattern}.
-@end deftypefn
 
 @hook TARGET_ASM_FUNCTION_BEGIN_EPILOGUE
-If defined, a function that outputs assembler code at the start of an
-epilogue.  This should be used when the function epilogue is being
-emitted as RTL, and you have some extra assembler that needs to be
-emitted.  @xref{epilogue instruction pattern}.
-@end deftypefn
 
 @hook TARGET_ASM_FUNCTION_EPILOGUE
-If defined, a function that outputs the assembler code for exit from a
-function.  The epilogue is responsible for restoring the saved
-registers and stack pointer to their values when the function was
-called, and returning control to the caller.  This macro takes the
-same arguments as the macro @code{TARGET_ASM_FUNCTION_PROLOGUE}, and the
-registers to restore are determined from @code{regs_ever_live} and
-@code{CALL_USED_REGISTERS} in the same way.
 
-On some machines, there is a single instruction that does all the work
-of returning from the function.  On these machines, give that
-instruction the name @samp{return} and do not define the macro
-@code{TARGET_ASM_FUNCTION_EPILOGUE} at all.
-
-Do not define a pattern named @samp{return} if you want the
-@code{TARGET_ASM_FUNCTION_EPILOGUE} to be used.  If you want the target
-switches to control whether return instructions or epilogues are used,
-define a @samp{return} pattern with a validity condition that tests the
-target switches appropriately.  If the @samp{return} pattern's validity
-condition is false, epilogues will be used.
-
-On machines where functions may or may not have frame-pointers, the
-function exit code must vary accordingly.  Sometimes the code for these
-two cases is completely different.  To determine whether a frame pointer
-is wanted, the macro can refer to the variable
-@code{frame_pointer_needed}.  The variable's value will be 1 when compiling
-a function that needs a frame pointer.
-
-Normally, @code{TARGET_ASM_FUNCTION_PROLOGUE} and
-@code{TARGET_ASM_FUNCTION_EPILOGUE} must treat leaf functions specially.
-The C variable @code{current_function_is_leaf} is nonzero for such a
-function.  @xref{Leaf Functions}.
-
-On some machines, some functions pop their arguments on exit while
-others leave that for the caller to do.  For example, the 68020 when
-given @option{-mrtd} pops arguments in functions that take a fixed
-number of arguments.
-
-@findex pops_args
-@findex crtl->args.pops_args
-Your definition of the macro @code{RETURN_POPS_ARGS} decides which
-functions pop their own arguments.  @code{TARGET_ASM_FUNCTION_EPILOGUE}
-needs to know what was decided.  The number of bytes of the current
-function's arguments that this function should pop is available in
-@code{crtl->args.pops_args}.  @xref{Scalar Return}.
-@end deftypefn
-
 @itemize @bullet
 @item
 @findex pretend_args_size
@@ -4789,54 +3922,8 @@ 
 @end defmac
 
 @hook TARGET_ASM_OUTPUT_MI_THUNK
-A function that outputs the assembler code for a thunk
-function, used to implement C++ virtual function calls with multiple
-inheritance.  The thunk acts as a wrapper around a virtual function,
-adjusting the implicit object parameter before handing control off to
-the real function.
 
-First, emit code to add the integer @var{delta} to the location that
-contains the incoming first argument.  Assume that this argument
-contains a pointer, and is the one used to pass the @code{this} pointer
-in C++.  This is the incoming argument @emph{before} the function prologue,
-e.g.@: @samp{%o0} on a sparc.  The addition must preserve the values of
-all other incoming arguments.
-
-Then, if @var{vcall_offset} is nonzero, an additional adjustment should be
-made after adding @code{delta}.  In particular, if @var{p} is the
-adjusted pointer, the following adjustment should be made:
-
-@smallexample
-p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
-@end smallexample
-
-After the additions, emit code to jump to @var{function}, which is a
-@code{FUNCTION_DECL}.  This is a direct pure jump, not a call, and does
-not touch the return address.  Hence returning from @var{FUNCTION} will
-return to whoever called the current @samp{thunk}.
-
-The effect must be as if @var{function} had been called directly with
-the adjusted first argument.  This macro is responsible for emitting all
-of the code for a thunk function; @code{TARGET_ASM_FUNCTION_PROLOGUE}
-and @code{TARGET_ASM_FUNCTION_EPILOGUE} are not invoked.
-
-The @var{thunk_fndecl} is redundant.  (@var{delta} and @var{function}
-have already been extracted from it.)  It might possibly be useful on
-some targets, but probably not.
-
-If you do not define this macro, the target-independent code in the C++
-front end will generate a less efficient heavyweight thunk that calls
-@var{function} instead of jumping to it.  The generic approach does
-not support varargs.
-@end deftypefn
-
 @hook TARGET_ASM_CAN_OUTPUT_MI_THUNK
-A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
-to output the assembler code for the thunk function specified by the
-arguments it is passed, and false otherwise.  In the latter case, the
-generic approach will be used by the C++ front end, with the limitations
-previously exposed.
-@end deftypefn
 
 @node Profiling
 @subsection Generating Code for Profiling
@@ -4884,26 +3971,8 @@ 
 @cindex tail calls
 
 @hook TARGET_FUNCTION_OK_FOR_SIBCALL
-True if it is ok to do sibling call optimization for the specified
-call expression @var{exp}.  @var{decl} will be the called function,
-or @code{NULL} if this is an indirect call.
 
-It is not uncommon for limitations of calling conventions to prevent
-tail calls to functions outside the current unit of translation, or
-during PIC compilation.  The hook is used to enforce these restrictions,
-as the @code{sibcall} md pattern can not fail, or fall over to a
-``normal'' call.  The criteria for successful sibling call optimization
-may vary greatly between different architectures.
-@end deftypefn
-
 @hook TARGET_EXTRA_LIVE_ON_ENTRY
-Add any hard registers to @var{regs} that are live on entry to the
-function.  This hook only needs to be defined to provide registers that
-cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
-registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
-TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
-FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
-@end deftypefn
 
 @hook TARGET_SET_UP_BY_PROLOGUE
 
@@ -4914,26 +3983,9 @@ 
 @cindex stack smashing protection
 
 @hook TARGET_STACK_PROTECT_GUARD
-This hook returns a @code{DECL} node for the external variable to use
-for the stack protection guard.  This variable is initialized by the
-runtime to some random value and is used to initialize the guard value
-that is placed at the top of the local stack frame.  The type of this
-variable must be @code{ptr_type_node}.
 
-The default version of this hook creates a variable called
-@samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}.
-@end deftypefn
-
 @hook TARGET_STACK_PROTECT_FAIL
-This hook returns a @code{CALL_EXPR} that alerts the runtime that the
-stack protect guard variable has been modified.  This expression should
-involve a call to a @code{noreturn} function.
 
-The default version of this hook invokes a function called
-@samp{__stack_chk_fail}, taking no arguments.  This function is
-normally defined in @file{libgcc2.c}.
-@end deftypefn
-
 @hook TARGET_SUPPORTS_SPLIT_STACK
 
 @node Varargs
@@ -5005,70 +4057,12 @@ 
 These machine description macros help implement varargs:
 
 @hook TARGET_EXPAND_BUILTIN_SAVEREGS
-If defined, this hook produces the machine-specific code for a call to
-@code{__builtin_saveregs}.  This code will be moved to the very
-beginning of the function, before any parameter access are made.  The
-return value of this function should be an RTX that contains the value
-to use as the return of @code{__builtin_saveregs}.
-@end deftypefn
 
 @hook TARGET_SETUP_INCOMING_VARARGS
-This target hook offers an alternative to using
-@code{__builtin_saveregs} and defining the hook
-@code{TARGET_EXPAND_BUILTIN_SAVEREGS}.  Use it to store the anonymous
-register arguments into the stack so that all the arguments appear to
-have been passed consecutively on the stack.  Once this is done, you can
-use the standard implementation of varargs that works for machines that
-pass all their arguments on the stack.
 
-The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data
-structure, containing the values that are obtained after processing the
-named arguments.  The arguments @var{mode} and @var{type} describe the
-last named argument---its machine mode and its data type as a tree node.
-
-The target hook should do two things: first, push onto the stack all the
-argument registers @emph{not} used for the named arguments, and second,
-store the size of the data thus pushed into the @code{int}-valued
-variable pointed to by @var{pretend_args_size}.  The value that you
-store here will serve as additional offset for setting up the stack
-frame.
-
-Because you must generate code to push the anonymous arguments at
-compile time without knowing their data types,
-@code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that
-have just a single category of argument register and use it uniformly
-for all data types.
-
-If the argument @var{second_time} is nonzero, it means that the
-arguments of the function are being analyzed for the second time.  This
-happens for an inline function, which is not actually compiled until the
-end of the source file.  The hook @code{TARGET_SETUP_INCOMING_VARARGS} should
-not generate any instructions in this case.
-@end deftypefn
-
 @hook TARGET_STRICT_ARGUMENT_NAMING
-Define this hook to return @code{true} if the location where a function
-argument is passed depends on whether or not it is a named argument.
 
-This hook controls how the @var{named} argument to @code{TARGET_FUNCTION_ARG}
-is set for varargs and stdarg functions.  If this hook returns
-@code{true}, the @var{named} argument is always true for named
-arguments, and false for unnamed arguments.  If it returns @code{false},
-but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true},
-then all arguments are treated as named.  Otherwise, all named arguments
-except the last are treated as named.
-
-You need not define this hook if it always returns @code{false}.
-@end deftypefn
-
 @hook TARGET_PRETEND_OUTGOING_VARARGS_NAMED
-If you need to conditionally change ABIs so that one works with
-@code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither
-@code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was
-defined, then define this hook to return @code{true} if
-@code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise.
-Otherwise, you should not define this hook.
-@end deftypefn
 
 @node Trampolines
 @section Trampolines for Nested Functions
@@ -5099,17 +4093,7 @@ 
 separately.
 
 @hook TARGET_ASM_TRAMPOLINE_TEMPLATE
-This hook is called by @code{assemble_trampoline_template} to output,
-on the stream @var{f}, assembler code for a block of data that contains
-the constant parts of a trampoline.  This code should not include a
-label---the label is taken care of automatically.
 
-If you do not define this hook, it means no template is needed
-for the target.  Do not define this hook on systems where the block move
-code to copy the trampoline into place would be larger than the code
-to generate it on the spot.
-@end deftypefn
-
 @defmac TRAMPOLINE_SECTION
 Return the section into which the trampoline template is to be placed
 (@pxref{Sections}).  The default value is @code{readonly_data_section}.
@@ -5127,33 +4111,8 @@ 
 @end defmac
 
 @hook TARGET_TRAMPOLINE_INIT
-This hook is called to initialize a trampoline.
-@var{m_tramp} is an RTX for the memory block for the trampoline; @var{fndecl}
-is the @code{FUNCTION_DECL} for the nested function; @var{static_chain} is an
-RTX for the static chain value that should be passed to the function
-when it is called.
 
-If the target defines @code{TARGET_ASM_TRAMPOLINE_TEMPLATE}, then the
-first thing this hook should do is emit a block move into @var{m_tramp}
-from the memory block returned by @code{assemble_trampoline_template}.
-Note that the block move need only cover the constant parts of the
-trampoline.  If the target isolates the variable parts of the trampoline
-to the end, not all @code{TRAMPOLINE_SIZE} bytes need be copied.
-
-If the target requires any other actions, such as flushing caches or
-enabling stack execution, these actions should be performed after
-initializing the trampoline proper.
-@end deftypefn
-
 @hook TARGET_TRAMPOLINE_ADJUST_ADDRESS
-This hook should perform any machine-specific adjustment in
-the address of the trampoline.  Its argument contains the address of the
-memory block that was passed to @code{TARGET_TRAMPOLINE_INIT}.  In case
-the address to be used for a function call should be different from the
-address at which the template was stored, the different address should
-be returned; otherwise @var{addr} should be returned unchanged.
-If this hook is not defined, @var{addr} will be used for function calls.
-@end deftypefn
 
 Implementing trampolines is difficult on many machines because they have
 separate instruction and data caches.  Writing into a stack location
@@ -5214,15 +4173,7 @@ 
 @findex set_optab_libfunc
 @findex init_one_libfunc
 @hook TARGET_INIT_LIBFUNCS
-This hook should declare additional library routines or rename
-existing ones, using the functions @code{set_optab_libfunc} and
-@code{init_one_libfunc} defined in @file{optabs.c}.
-@code{init_optabs} calls this macro after initializing all the normal
-library routines.
 
-The default is to do nothing.  Most ports don't need to define this hook.
-@end deftypefn
-
 @hook TARGET_LIBFUNC_GNU_PREFIX
 
 @defmac FLOAT_LIB_COMPARE_RETURNS_BOOL (@var{mode}, @var{comparison})
@@ -5358,70 +4309,7 @@ 
 @end defmac
 
 @hook TARGET_LEGITIMATE_ADDRESS_P
-A function that returns whether @var{x} (an RTX) is a legitimate memory
-address on the target machine for a memory operand of mode @var{mode}.
 
-Legitimate addresses are defined in two variants: a strict variant and a
-non-strict one.  The @var{strict} parameter chooses which variant is
-desired by the caller.
-
-The strict variant is used in the reload pass.  It must be defined so
-that any pseudo-register that has not been allocated a hard register is
-considered a memory reference.  This is because in contexts where some
-kind of register is required, a pseudo-register with no hard register
-must be rejected.  For non-hard registers, the strict variant should look
-up the @code{reg_renumber} array; it should then proceed using the hard
-register number in the array, or treat the pseudo as a memory reference
-if the array holds @code{-1}.
-
-The non-strict variant is used in other passes.  It must be defined to
-accept all pseudo-registers in every context where some kind of
-register is required.
-
-Normally, constant addresses which are the sum of a @code{symbol_ref}
-and an integer are stored inside a @code{const} RTX to mark them as
-constant.  Therefore, there is no need to recognize such sums
-specifically as legitimate addresses.  Normally you would simply
-recognize any @code{const} as legitimate.
-
-Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant
-sums that are not marked with  @code{const}.  It assumes that a naked
-@code{plus} indicates indexing.  If so, then you @emph{must} reject such
-naked constant sums as illegitimate addresses, so that none of them will
-be given to @code{PRINT_OPERAND_ADDRESS}.
-
-@cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation
-On some machines, whether a symbolic address is legitimate depends on
-the section that the address refers to.  On these machines, define the
-target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information
-into the @code{symbol_ref}, and then check for it here.  When you see a
-@code{const}, you will have to look inside it to find the
-@code{symbol_ref} in order to determine the section.  @xref{Assembler
-Format}.
-
-@cindex @code{GO_IF_LEGITIMATE_ADDRESS}
-Some ports are still using a deprecated legacy substitute for
-this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro.  This macro
-has this syntax:
-
-@example
-#define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label})
-@end example
-
-@noindent
-and should @code{goto @var{label}} if the address @var{x} is a valid
-address on the target machine for a memory operand of mode @var{mode}.
-
-@findex REG_OK_STRICT
-Compiler source files that want to use the strict variant of this
-macro define the macro @code{REG_OK_STRICT}.  You should use an
-@code{#ifdef REG_OK_STRICT} conditional to define the strict variant in
-that case and the non-strict variant otherwise.
-
-Using the hook is usually simpler because it limits the number of
-files that are recompiled when changes are made.
-@end deftypefn
-
 @defmac TARGET_MEM_CONSTRAINT
 A single character to be used instead of the default @code{'m'}
 character for general memory addresses.  This defines the constraint
@@ -5447,28 +4335,7 @@ 
 @end defmac
 
 @hook TARGET_LEGITIMIZE_ADDRESS
-This hook is given an invalid memory address @var{x} for an
-operand of mode @var{mode} and should try to return a valid memory
-address.
 
-@findex break_out_memory_refs
-@var{x} will always be the result of a call to @code{break_out_memory_refs},
-and @var{oldx} will be the operand that was given to that function to produce
-@var{x}.
-
-The code of the hook should not alter the substructure of
-@var{x}.  If it transforms @var{x} into a more legitimate form, it
-should return the new @var{x}.
-
-It is not necessary for this hook to come up with a legitimate address,
-with the exception of native TLS addresses (@pxref{Emulated TLS}).
-The compiler has standard ways of doing so in all cases.  In fact, if
-the target supports only emulated TLS, it
-is safe to omit this hook or make it return @var{x} if it cannot find
-a valid way to legitimize the address.  But often a machine-dependent
-strategy can generate better code.
-@end deftypefn
-
 @defmac LEGITIMIZE_RELOAD_ADDRESS (@var{x}, @var{mode}, @var{opnum}, @var{type}, @var{ind_levels}, @var{win})
 A C compound statement that attempts to replace @var{x}, which is an address
 that needs reloading, with a valid memory address for an operand of mode
@@ -5519,169 +4386,38 @@ 
 @end defmac
 
 @hook TARGET_MODE_DEPENDENT_ADDRESS_P
-This hook returns @code{true} if memory address @var{addr} in address
-space @var{addrspace} can have
-different meanings depending on the machine mode of the memory
-reference it is used for or if the address is valid for some modes
-but not others.
 
-Autoincrement and autodecrement addresses typically have mode-dependent
-effects because the amount of the increment or decrement is the size
-of the operand being addressed.  Some machines have other mode-dependent
-addresses.  Many RISC machines have no mode-dependent addresses.
-
-You may assume that @var{addr} is a valid address for the machine.
-
-The default version of this hook returns @code{false}.
-@end deftypefn
-
 @hook TARGET_LEGITIMATE_CONSTANT_P
-This hook returns true if @var{x} is a legitimate constant for a
-@var{mode}-mode immediate operand on the target machine.  You can assume that
-@var{x} satisfies @code{CONSTANT_P}, so you need not check this.
 
-The default definition returns true.
-@end deftypefn
-
 @hook TARGET_DELEGITIMIZE_ADDRESS
-This hook is used to undo the possibly obfuscating effects of the
-@code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target
-macros.  Some backend implementations of these macros wrap symbol
-references inside an @code{UNSPEC} rtx to represent PIC or similar
-addressing modes.  This target hook allows GCC's optimizers to understand
-the semantics of these opaque @code{UNSPEC}s by converting them back
-into their original form.
-@end deftypefn
 
 @hook TARGET_CONST_NOT_OK_FOR_DEBUG_P
-This hook should return true if @var{x} should not be emitted into
-debug sections.
-@end deftypefn
 
 @hook TARGET_CANNOT_FORCE_CONST_MEM
-This hook should return true if @var{x} is of a form that cannot (or
-should not) be spilled to the constant pool.  @var{mode} is the mode
-of @var{x}.
 
-The default version of this hook returns false.
-
-The primary reason to define this hook is to prevent reload from
-deciding that a non-legitimate constant would be better reloaded
-from the constant pool instead of spilling and reloading a register
-holding the constant.  This restriction is often true of addresses
-of TLS symbols for various targets.
-@end deftypefn
-
 @hook TARGET_USE_BLOCKS_FOR_CONSTANT_P
-This hook should return true if pool entries for constant @var{x} can
-be placed in an @code{object_block} structure.  @var{mode} is the mode
-of @var{x}.
 
-The default version returns false for all constants.
-@end deftypefn
-
 @hook TARGET_USE_BLOCKS_FOR_DECL_P
-This hook should return true if pool entries for @var{decl} should
-be placed in an @code{object_block} structure.
 
-The default version returns true for all decls.
-@end deftypefn
-
 @hook TARGET_BUILTIN_RECIPROCAL
-This hook should return the DECL of a function that implements reciprocal of
-the builtin function with builtin function code @var{fn}, or
-@code{NULL_TREE} if such a function is not available.  @var{md_fn} is true
-when @var{fn} is a code of a machine-dependent builtin function.  When
-@var{sqrt} is true, additional optimizations that apply only to the reciprocal
-of a square root function are performed, and only reciprocals of @code{sqrt}
-function are valid.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD
-This hook should return the DECL of a function @var{f} that given an
-address @var{addr} as an argument returns a mask @var{m} that can be
-used to extract from two vectors the relevant data that resides in
-@var{addr} in case @var{addr} is not properly aligned.
 
-The autovectorizer, when vectorizing a load operation from an address
-@var{addr} that may be unaligned, will generate two vector loads from
-the two aligned addresses around @var{addr}. It then generates a
-@code{REALIGN_LOAD} operation to extract the relevant data from the
-two loaded vectors. The first two arguments to @code{REALIGN_LOAD},
-@var{v1} and @var{v2}, are the two vectors, each of size @var{VS}, and
-the third argument, @var{OFF}, defines how the data will be extracted
-from these two vectors: if @var{OFF} is 0, then the returned vector is
-@var{v2}; otherwise, the returned vector is composed from the last
-@var{VS}-@var{OFF} elements of @var{v1} concatenated to the first
-@var{OFF} elements of @var{v2}.
-
-If this hook is defined, the autovectorizer will generate a call
-to @var{f} (using the DECL tree that this hook returns) and will
-use the return value of @var{f} as the argument @var{OFF} to
-@code{REALIGN_LOAD}. Therefore, the mask @var{m} returned by @var{f}
-should comply with the semantics expected by @code{REALIGN_LOAD}
-described above.
-If this hook is not defined, then @var{addr} will be used as
-the argument @var{OFF} to @code{REALIGN_LOAD}, in which case the low
-log2(@var{VS}) @minus{} 1 bits of @var{addr} will be considered.
-@end deftypefn
-
 @hook TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST
-Returns cost of different scalar or vector statements for vectorization cost model.
-For vector memory operations the cost may depend on type (@var{vectype}) and
-misalignment value (@var{misalign}).
-@end deftypefn
 
 @hook TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE
-Return true if vector alignment is reachable (by peeling N iterations) for the given type.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_VEC_PERM_CONST_OK
-Return true if a vector created for @code{vec_perm_const} is valid.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_BUILTIN_CONVERSION
-This hook should return the DECL of a function that implements conversion of the
-input vector of type @var{src_type} to type @var{dest_type}.
-The value of @var{code} is one of the enumerators in @code{enum tree_code} and
-specifies how the conversion is to be applied
-(truncation, rounding, etc.).
 
-If this hook is defined, the autovectorizer will use the
-@code{TARGET_VECTORIZE_BUILTIN_CONVERSION} target hook when vectorizing
-conversion. Otherwise, it will return @code{NULL_TREE}.
-@end deftypefn
-
 @hook TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION
-This hook should return the decl of a function that implements the
-vectorized variant of the builtin function with builtin function code
-@var{code} or @code{NULL_TREE} if such a function is not available.
-The value of @var{fndecl} is the builtin function declaration.  The
-return type of the vectorized function shall be of vector type
-@var{vec_type_out} and the argument types should be @var{vec_type_in}.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT
-This hook should return true if the target supports misaligned vector
-store/load of a specific factor denoted in the @var{misalignment}
-parameter.  The vector store/load should be of machine mode @var{mode} and
-the elements in the vectors should be of type @var{type}.  @var{is_packed}
-parameter is true if the memory access is defined in a packed struct.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_PREFERRED_SIMD_MODE
-This hook should return the preferred mode for vectorizing scalar
-mode @var{mode}.  The default is
-equal to @code{word_mode}, because the vectorizer can do some
-transformations even in absence of specialized @acronym{SIMD} hardware.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_SIZES
-This hook should return a mask of sizes that should be iterated over
-after trying to autovectorize using the vector size derived from the
-mode returned by @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE}.
-The default is zero which means to not iterate over other vector sizes.
-@end deftypefn
 
 @hook TARGET_VECTORIZE_INIT_COST
 
@@ -5696,12 +4432,6 @@ 
 @hook TARGET_VECTORIZE_BUILTIN_TM_STORE
 
 @hook TARGET_VECTORIZE_BUILTIN_GATHER
-Target builtin that implements vector gather operation.  @var{mem_vectype}
-is the vector type of the load and @var{index_type} is scalar type of
-the index, scaled by @var{scale}.
-The default is @code{NULL_TREE} which means to not vectorize gather
-loads.
-@end deftypefn
 
 @node Anchored Addresses
 @section Anchored Addresses
@@ -5739,40 +4469,13 @@ 
 or @code{TARGET_MAX_ANCHOR_OFFSET} is set to a nonzero value.
 
 @hook TARGET_MIN_ANCHOR_OFFSET
-The minimum offset that should be applied to a section anchor.
-On most targets, it should be the smallest offset that can be
-applied to a base register while still giving a legitimate address
-for every mode.  The default value is 0.
-@end deftypevr
 
 @hook TARGET_MAX_ANCHOR_OFFSET
-Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive)
-offset that should be applied to section anchors.  The default
-value is 0.
-@end deftypevr
 
 @hook TARGET_ASM_OUTPUT_ANCHOR
-Write the assembly code to define section anchor @var{x}, which is a
-@code{SYMBOL_REF} for which @samp{SYMBOL_REF_ANCHOR_P (@var{x})} is true.
-The hook is called with the assembly output position set to the beginning
-of @code{SYMBOL_REF_BLOCK (@var{x})}.
 
-If @code{ASM_OUTPUT_DEF} is available, the hook's default definition uses
-it to define the symbol as @samp{. + SYMBOL_REF_BLOCK_OFFSET (@var{x})}.
-If @code{ASM_OUTPUT_DEF} is not available, the hook's default definition
-is @code{NULL}, which disables the use of section anchors altogether.
-@end deftypefn
-
 @hook TARGET_USE_ANCHORS_FOR_SYMBOL_P
-Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF}
-@var{x}.  You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and
-@samp{!SYMBOL_REF_ANCHOR_P (@var{x})}.
 
-The default version is correct for most targets, but you might need to
-intercept this hook to handle things like target-specific attributes
-or target-specific sections.
-@end deftypefn
-
 @node Condition Code
 @section Condition Code Status
 @cindex condition code status
@@ -5941,27 +4644,7 @@ 
 @end defmac
 
 @hook TARGET_CANONICALIZE_COMPARISON
-On some machines not all possible comparisons are defined, but you can
-convert an invalid comparison into a valid one.  For example, the Alpha
-does not have a @code{GT} comparison, but you can use an @code{LT}
-comparison instead and swap the order of the operands.
 
-On such machines, implement this hook to do any required conversions.
-@var{code} is the initial comparison code and @var{op0} and @var{op1}
-are the left and right operands of the comparison, respectively.  If
-@var{op0_preserve_value} is @code{true} the implementation is not
-allowed to change the value of @var{op0} since the value might be used
-in RTXs which aren't comparisons.  E.g. the implementation is not
-allowed to swap operands in that case.
-
-GCC will not assume that the comparison resulting from this macro is
-valid but will see if the resulting insn matches a pattern in the
-@file{md} file.
-
-You need not to implement this hook if it would never change the
-comparison code or operands.
-@end deftypefn
-
 @defmac REVERSIBLE_CC_MODE (@var{mode})
 A C expression whose value is one if it is always safe to reverse a
 comparison whose mode is @var{mode}.  If @code{SELECT_CC_MODE}
@@ -5995,33 +4678,9 @@ 
 @end defmac
 
 @hook TARGET_FIXED_CONDITION_CODE_REGS
-On targets which do not use @code{(cc0)}, and which use a hard
-register rather than a pseudo-register to hold condition codes, the
-regular CSE passes are often not able to identify cases in which the
-hard register is set to a common value.  Use this hook to enable a
-small pass which optimizes such cases.  This hook should return true
-to enable this pass, and it should set the integers to which its
-arguments point to the hard register numbers used for condition codes.
-When there is only one such register, as is true on most systems, the
-integer pointed to by @var{p2} should be set to
-@code{INVALID_REGNUM}.
 
-The default version of this hook returns false.
-@end deftypefn
-
 @hook TARGET_CC_MODES_COMPATIBLE
-On targets which use multiple condition code modes in class
-@code{MODE_CC}, it is sometimes the case that a comparison can be
-validly done in more than one mode.  On such a system, define this
-target hook to take two mode arguments and to return a mode in which
-both comparisons may be validly done.  If there is no such mode,
-return @code{VOIDmode}.
 
-The default version of this hook checks whether the modes are the
-same.  If they are, it returns that mode.  If they are different, it
-returns @code{VOIDmode}.
-@end deftypefn
-
 @node Cond Exec Macros
 @subsection Macros to control conditional execution
 @findex conditional execution
@@ -6063,26 +4722,7 @@ 
 @end defmac
 
 @hook TARGET_REGISTER_MOVE_COST
-This target hook should return the cost of moving data of mode @var{mode}
-from a register in class @var{from} to one in class @var{to}.  The classes
-are expressed using the enumeration values such as @code{GENERAL_REGS}.
-A value of 2 is the default; other values are interpreted relative to
-that.
 
-It is not required that the cost always equal 2 when @var{from} is the
-same as @var{to}; on some machines it is expensive to move between
-registers if they are not general registers.
-
-If reload sees an insn consisting of a single @code{set} between two
-hard registers, and if @code{TARGET_REGISTER_MOVE_COST} applied to their
-classes returns a value of 2, reload does not check to ensure that the
-constraints of the insn are met.  Setting a cost of other than 2 will
-allow reload to verify that the constraints are met.  You should do this
-if the @samp{mov@var{m}} pattern's constraints do not allow such copying.
-
-The default version of this function returns 2.
-@end deftypefn
-
 @defmac MEMORY_MOVE_COST (@var{mode}, @var{class}, @var{in})
 A C expression for the cost of moving data of mode @var{mode} between a
 register of class @var{class} and memory; @var{in} is zero if the value
@@ -6111,29 +4751,7 @@ 
 @end defmac
 
 @hook TARGET_MEMORY_MOVE_COST
-This target hook should return the cost of moving data of mode @var{mode}
-between a register of class @var{rclass} and memory; @var{in} is @code{false}
-if the value is to be written to memory, @code{true} if it is to be read in.
-This cost is relative to those in @code{TARGET_REGISTER_MOVE_COST}.
-If moving between registers and memory is more expensive than between two
-registers, you should add this target hook to express the relative cost.
 
-If you do not add this target hook, GCC uses a default cost of 4 plus
-the cost of copying via a secondary reload register, if one is
-needed.  If your machine requires a secondary reload register to copy
-between memory and a register of @var{rclass} but the reload mechanism is
-more complex than copying via an intermediate, use this target hook to
-reflect the actual cost of the move.
-
-GCC defines the function @code{memory_move_secondary_cost} if
-secondary reloads are needed.  It computes the costs due to copying via
-a secondary register.  If your machine copies from memory using a
-secondary register in the conventional way but the default base value of
-4 is not correct for your machine, use this target hook to add some other
-value to the result of that function.  The arguments to that function
-are the same as to this target hook.
-@end deftypefn
-
 @defmac BRANCH_COST (@var{speed_p}, @var{predictable_p})
 A C expression for the cost of a branch instruction.  A value of 1 is
 the default; other values are interpreted relative to that. Parameter
@@ -6318,72 +4936,9 @@ 
 @end defmac
 
 @hook TARGET_RTX_COSTS
-This target hook describes the relative costs of RTL expressions.
 
-The cost may depend on the precise form of the expression, which is
-available for examination in @var{x}, and the fact that @var{x} appears
-as operand @var{opno} of an expression with rtx code @var{outer_code}.
-That is, the hook can assume that there is some rtx @var{y} such
-that @samp{GET_CODE (@var{y}) == @var{outer_code}} and such that
-either (a) @samp{XEXP (@var{y}, @var{opno}) == @var{x}} or
-(b) @samp{XVEC (@var{y}, @var{opno})} contains @var{x}.
-
-@var{code} is @var{x}'s expression code---redundant, since it can be
-obtained with @code{GET_CODE (@var{x})}.
-
-In implementing this hook, you can use the construct
-@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast
-instructions.
-
-On entry to the hook, @code{*@var{total}} contains a default estimate
-for the cost of the expression.  The hook should modify this value as
-necessary.  Traditionally, the default costs are @code{COSTS_N_INSNS (5)}
-for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus
-operations, and @code{COSTS_N_INSNS (1)} for all other operations.
-
-When optimizing for code size, i.e.@: when @code{speed} is
-false, this target hook should be used to estimate the relative
-size cost of an expression, again relative to @code{COSTS_N_INSNS}.
-
-The hook returns true when all subexpressions of @var{x} have been
-processed, and false when @code{rtx_cost} should recurse.
-@end deftypefn
-
 @hook TARGET_ADDRESS_COST
-This hook computes the cost of an addressing mode that contains
-@var{address}.  If not defined, the cost is computed from
-the @var{address} expression and the @code{TARGET_RTX_COST} hook.
 
-For most CISC machines, the default cost is a good approximation of the
-true cost of the addressing mode.  However, on RISC machines, all
-instructions normally have the same length and execution time.  Hence
-all addresses will have equal costs.
-
-In cases where more than one form of an address is known, the form with
-the lowest cost will be used.  If multiple forms have the same, lowest,
-cost, the one that is the most complex will be used.
-
-For example, suppose an address that is equal to the sum of a register
-and a constant is used twice in the same basic block.  When this macro
-is not defined, the address will be computed in a register and memory
-references will be indirect through that register.  On machines where
-the cost of the addressing mode containing the sum is no higher than
-that of a simple indirect reference, this will produce an additional
-instruction and possibly require an additional register.  Proper
-specification of this macro eliminates this overhead for such machines.
-
-This hook is never called with an invalid address.
-
-On machines where an address involving more than one register is as
-cheap as an address computation involving only one register, defining
-@code{TARGET_ADDRESS_COST} to reflect this can cause two registers to
-be live over a region of code where only one would have been if
-@code{TARGET_ADDRESS_COST} were not defined in that manner.  This effect
-should be considered in the definition of this macro.  Equivalent costs
-should probably only be given to addresses with different numbers of
-registers on machines with lots of registers.
-@end deftypefn
-
 @node Scheduling
 @section Adjusting the Instruction Scheduler
 
@@ -6393,357 +4948,86 @@ 
 them: try the first ones in this list first.
 
 @hook TARGET_SCHED_ISSUE_RATE
-This hook returns the maximum number of instructions that can ever
-issue at the same time on the target machine.  The default is one.
-Although the insn scheduler can define itself the possibility of issue
-an insn on the same cycle, the value can serve as an additional
-constraint to issue insns on the same simulated processor cycle (see
-hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}).
-This value must be constant over the entire compilation.  If you need
-it to vary depending on what the instructions are, you must use
-@samp{TARGET_SCHED_VARIABLE_ISSUE}.
-@end deftypefn
 
 @hook TARGET_SCHED_VARIABLE_ISSUE
-This hook is executed by the scheduler after it has scheduled an insn
-from the ready list.  It should return the number of insns which can
-still be issued in the current cycle.  The default is
-@samp{@w{@var{more} - 1}} for insns other than @code{CLOBBER} and
-@code{USE}, which normally are not counted against the issue rate.
-You should define this hook if some insns take more machine resources
-than others, so that fewer insns can follow them in the same cycle.
-@var{file} is either a null pointer, or a stdio stream to write any
-debug output to.  @var{verbose} is the verbose level provided by
-@option{-fsched-verbose-@var{n}}.  @var{insn} is the instruction that
-was scheduled.
-@end deftypefn
 
 @hook TARGET_SCHED_ADJUST_COST
-This function corrects the value of @var{cost} based on the
-relationship between @var{insn} and @var{dep_insn} through the
-dependence @var{link}.  It should return the new value.  The default
-is to make no adjustment to @var{cost}.  This can be used for example
-to specify to the scheduler using the traditional pipeline description
-that an output- or anti-dependence does not incur the same cost as a
-data-dependence.  If the scheduler using the automaton based pipeline
-description, the cost of anti-dependence is zero and the cost of
-output-dependence is maximum of one and the difference of latency
-times of the first and the second insns.  If these values are not
-acceptable, you could use the hook to modify them too.  See also
-@pxref{Processor pipeline description}.
-@end deftypefn
 
 @hook TARGET_SCHED_ADJUST_PRIORITY
-This hook adjusts the integer scheduling priority @var{priority} of
-@var{insn}.  It should return the new priority.  Increase the priority to
-execute @var{insn} earlier, reduce the priority to execute @var{insn}
-later.  Do not define this hook if you do not need to adjust the
-scheduling priorities of insns.
-@end deftypefn
 
 @hook TARGET_SCHED_REORDER
-This hook is executed by the scheduler after it has scheduled the ready
-list, to allow the machine description to reorder it (for example to
-combine two small instructions together on @samp{VLIW} machines).
-@var{file} is either a null pointer, or a stdio stream to write any
-debug output to.  @var{verbose} is the verbose level provided by
-@option{-fsched-verbose-@var{n}}.  @var{ready} is a pointer to the ready
-list of instructions that are ready to be scheduled.  @var{n_readyp} is
-a pointer to the number of elements in the ready list.  The scheduler
-reads the ready list in reverse order, starting with
-@var{ready}[@var{*n_readyp} @minus{} 1] and going to @var{ready}[0].  @var{clock}
-is the timer tick of the scheduler.  You may modify the ready list and
-the number of ready insns.  The return value is the number of insns that
-can issue this cycle; normally this is just @code{issue_rate}.  See also
-@samp{TARGET_SCHED_REORDER2}.
-@end deftypefn
 
 @hook TARGET_SCHED_REORDER2
-Like @samp{TARGET_SCHED_REORDER}, but called at a different time.  That
-function is called whenever the scheduler starts a new cycle.  This one
-is called once per iteration over a cycle, immediately after
-@samp{TARGET_SCHED_VARIABLE_ISSUE}; it can reorder the ready list and
-return the number of insns to be scheduled in the same cycle.  Defining
-this hook can be useful if there are frequent situations where
-scheduling one insn causes other insns to become ready in the same
-cycle.  These other insns can then be taken into account properly.
-@end deftypefn
 
 @hook TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK
-This hook is called after evaluation forward dependencies of insns in
-chain given by two parameter values (@var{head} and @var{tail}
-correspondingly) but before insns scheduling of the insn chain.  For
-example, it can be used for better insn classification if it requires
-analysis of dependencies.  This hook can use backward and forward
-dependencies of the insn scheduler because they are already
-calculated.
-@end deftypefn
 
 @hook TARGET_SCHED_INIT
-This hook is executed by the scheduler at the beginning of each block of
-instructions that are to be scheduled.  @var{file} is either a null
-pointer, or a stdio stream to write any debug output to.  @var{verbose}
-is the verbose level provided by @option{-fsched-verbose-@var{n}}.
-@var{max_ready} is the maximum number of insns in the current scheduling
-region that can be live at the same time.  This can be used to allocate
-scratch space if it is needed, e.g.@: by @samp{TARGET_SCHED_REORDER}.
-@end deftypefn
 
 @hook TARGET_SCHED_FINISH
-This hook is executed by the scheduler at the end of each block of
-instructions that are to be scheduled.  It can be used to perform
-cleanup of any actions done by the other scheduling hooks.  @var{file}
-is either a null pointer, or a stdio stream to write any debug output
-to.  @var{verbose} is the verbose level provided by
-@option{-fsched-verbose-@var{n}}.
-@end deftypefn
 
 @hook TARGET_SCHED_INIT_GLOBAL
-This hook is executed by the scheduler after function level initializations.
-@var{file} is either a null pointer, or a stdio stream to write any debug output to.
-@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.
-@var{old_max_uid} is the maximum insn uid when scheduling begins.
-@end deftypefn
 
 @hook TARGET_SCHED_FINISH_GLOBAL
-This is the cleanup hook corresponding to @code{TARGET_SCHED_INIT_GLOBAL}.
-@var{file} is either a null pointer, or a stdio stream to write any debug output to.
-@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.
-@end deftypefn
 
 @hook TARGET_SCHED_DFA_PRE_CYCLE_INSN
-The hook returns an RTL insn.  The automaton state used in the
-pipeline hazard recognizer is changed as if the insn were scheduled
-when the new simulated processor cycle starts.  Usage of the hook may
-simplify the automaton pipeline description for some @acronym{VLIW}
-processors.  If the hook is defined, it is used only for the automaton
-based pipeline description.  The default is not to change the state
-when the new simulated processor cycle starts.
-@end deftypefn
 
 @hook TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN
-The hook can be used to initialize data used by the previous hook.
-@end deftypefn
 
 @hook TARGET_SCHED_DFA_POST_CYCLE_INSN
-The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used
-to changed the state as if the insn were scheduled when the new
-simulated processor cycle finishes.
-@end deftypefn
 
 @hook TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN
-The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but
-used to initialize data used by the previous hook.
-@end deftypefn
 
 @hook TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE
-The hook to notify target that the current simulated cycle is about to finish.
-The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used
-to change the state in more complicated situations - e.g., when advancing
-state on a single insn is not enough.
-@end deftypefn
 
 @hook TARGET_SCHED_DFA_POST_ADVANCE_CYCLE
-The hook to notify target that new simulated cycle has just started.
-The hook is analogous to @samp{TARGET_SCHED_DFA_POST_CYCLE_INSN} but used
-to change the state in more complicated situations - e.g., when advancing
-state on a single insn is not enough.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD
-This hook controls better choosing an insn from the ready insn queue
-for the @acronym{DFA}-based insn scheduler.  Usually the scheduler
-chooses the first insn from the queue.  If the hook returns a positive
-value, an additional scheduler code tries all permutations of
-@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()}
-subsequent ready insns to choose an insn whose issue will result in
-maximal number of issued insns on the same cycle.  For the
-@acronym{VLIW} processor, the code could actually solve the problem of
-packing simple insns into the @acronym{VLIW} insn.  Of course, if the
-rules of @acronym{VLIW} packing are described in the automaton.
 
-This code also could be used for superscalar @acronym{RISC}
-processors.  Let us consider a superscalar @acronym{RISC} processor
-with 3 pipelines.  Some insns can be executed in pipelines @var{A} or
-@var{B}, some insns can be executed only in pipelines @var{B} or
-@var{C}, and one insn can be executed in pipeline @var{B}.  The
-processor may issue the 1st insn into @var{A} and the 2nd one into
-@var{B}.  In this case, the 3rd insn will wait for freeing @var{B}
-until the next cycle.  If the scheduler issues the 3rd insn the first,
-the processor could issue all 3 insns per cycle.
-
-Actually this code demonstrates advantages of the automaton based
-pipeline hazard recognizer.  We try quickly and easy many insn
-schedules to choose the best one.
-
-The default is no multipass scheduling.
-@end deftypefn
-
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD
 
-This hook controls what insns from the ready insn queue will be
-considered for the multipass insn scheduling.  If the hook returns
-zero for @var{insn}, the insn will be not chosen to
-be issued.
-
-The default is that any ready insns can be chosen to be issued.
-@end deftypefn
-
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN
-This hook prepares the target backend for a new round of multipass
-scheduling.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE
-This hook is called when multipass scheduling evaluates instruction INSN.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK
-This is called when multipass scheduling backtracks from evaluation of
-an instruction.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END
-This hook notifies the target about the result of the concluded current
-round of multipass scheduling.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT
-This hook initializes target-specific data used in multipass scheduling.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI
-This hook finalizes target-specific data used in multipass scheduling.
-@end deftypefn
 
 @hook TARGET_SCHED_DFA_NEW_CYCLE
-This hook is called by the insn scheduler before issuing @var{insn}
-on cycle @var{clock}.  If the hook returns nonzero,
-@var{insn} is not issued on this processor cycle.  Instead,
-the processor cycle is advanced.  If *@var{sort_p}
-is zero, the insn ready queue is not sorted on the new cycle
-start as usually.  @var{dump} and @var{verbose} specify the file and
-verbosity level to use for debugging output.
-@var{last_clock} and @var{clock} are, respectively, the
-processor cycle on which the previous insn has been issued,
-and the current processor cycle.
-@end deftypefn
 
 @hook TARGET_SCHED_IS_COSTLY_DEPENDENCE
-This hook is used to define which dependences are considered costly by
-the target, so costly that it is not advisable to schedule the insns that
-are involved in the dependence too close to one another.  The parameters
-to this hook are as follows:  The first parameter @var{_dep} is the dependence
-being evaluated.  The second parameter @var{cost} is the cost of the
-dependence as estimated by the scheduler, and the third
-parameter @var{distance} is the distance in cycles between the two insns.
-The hook returns @code{true} if considering the distance between the two
-insns the dependence between them is considered costly by the target,
-and @code{false} otherwise.
 
-Defining this hook can be useful in multiple-issue out-of-order machines,
-where (a) it's practically hopeless to predict the actual data/resource
-delays, however: (b) there's a better chance to predict the actual grouping
-that will be formed, and (c) correctly emulating the grouping can be very
-important.  In such targets one may want to allow issuing dependent insns
-closer to one another---i.e., closer than the dependence distance;  however,
-not in cases of ``costly dependences'', which this hooks allows to define.
-@end deftypefn
-
 @hook TARGET_SCHED_H_I_D_EXTENDED
-This hook is called by the insn scheduler after emitting a new instruction to
-the instruction stream.  The hook notifies a target backend to extend its
-per instruction data structures.
-@end deftypefn
 
 @hook TARGET_SCHED_ALLOC_SCHED_CONTEXT
-Return a pointer to a store large enough to hold target scheduling context.
-@end deftypefn
 
 @hook TARGET_SCHED_INIT_SCHED_CONTEXT
-Initialize store pointed to by @var{tc} to hold target scheduling context.
-It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the
-beginning of the block.  Otherwise, copy the current context into @var{tc}.
-@end deftypefn
 
 @hook TARGET_SCHED_SET_SCHED_CONTEXT
-Copy target scheduling context pointed to by @var{tc} to the current context.
-@end deftypefn
 
 @hook TARGET_SCHED_CLEAR_SCHED_CONTEXT
-Deallocate internal data in target scheduling context pointed to by @var{tc}.
-@end deftypefn
 
 @hook TARGET_SCHED_FREE_SCHED_CONTEXT
-Deallocate a store for target scheduling context pointed to by @var{tc}.
-@end deftypefn
 
 @hook TARGET_SCHED_SPECULATE_INSN
-This hook is called by the insn scheduler when @var{insn} has only
-speculative dependencies and therefore can be scheduled speculatively.
-The hook is used to check if the pattern of @var{insn} has a speculative
-version and, in case of successful check, to generate that speculative
-pattern.  The hook should return 1, if the instruction has a speculative form,
-or @minus{}1, if it doesn't.  @var{request} describes the type of requested
-speculation.  If the return value equals 1 then @var{new_pat} is assigned
-the generated speculative pattern.
-@end deftypefn
 
 @hook TARGET_SCHED_NEEDS_BLOCK_P
-This hook is called by the insn scheduler during generation of recovery code
-for @var{insn}.  It should return @code{true}, if the corresponding check
-instruction should branch to recovery code, or @code{false} otherwise.
-@end deftypefn
 
 @hook TARGET_SCHED_GEN_SPEC_CHECK
-This hook is called by the insn scheduler to generate a pattern for recovery
-check instruction.  If @var{mutate_p} is zero, then @var{insn} is a
-speculative instruction for which the check should be generated.
-@var{label} is either a label of a basic block, where recovery code should
-be emitted, or a null pointer, when requested check doesn't branch to
-recovery code (a simple check).  If @var{mutate_p} is nonzero, then
-a pattern for a branchy check corresponding to a simple check denoted by
-@var{insn} should be generated.  In this case @var{label} can't be null.
-@end deftypefn
 
 @hook TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC
-This hook is used as a workaround for
-@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD} not being
-called on the first instruction of the ready list.  The hook is used to
-discard speculative instructions that stand first in the ready list from
-being scheduled on the current cycle.  If the hook returns @code{false},
-@var{insn} will not be chosen to be issued.
-For non-speculative instructions,
-the hook should always return @code{true}.  For example, in the ia64 backend
-the hook is used to cancel data speculative insns when the ALAT table
-is nearly full.
-@end deftypefn
 
 @hook TARGET_SCHED_SET_SCHED_FLAGS
-This hook is used by the insn scheduler to find out what features should be
-enabled/used.
-The structure *@var{spec_info} should be filled in by the target.
-The structure describes speculation types that can be used in the scheduler.
-@end deftypefn
 
 @hook TARGET_SCHED_SMS_RES_MII
-This hook is called by the swing modulo scheduler to calculate a
-resource-based lower bound which is based on the resources available in
-the machine and the resources required by each instruction.  The target
-backend can use @var{g} to calculate such bound.  A very simple lower
-bound will be used in case this hook is not implemented: the total number
-of instructions divided by the issue rate.
-@end deftypefn
 
 @hook TARGET_SCHED_DISPATCH
-This hook is called by Haifa Scheduler.  It returns true if dispatch scheduling
-is supported in hardware and the condition specified in the parameter is true.
-@end deftypefn
 
 @hook TARGET_SCHED_DISPATCH_DO
-This hook is called by Haifa Scheduler.  It performs the operation specified
-in its second parameter.
-@end deftypefn
 
 @hook TARGET_SCHED_EXPOSED_PIPELINE
 
@@ -6925,41 +5209,11 @@ 
 @end defmac
 
 @hook TARGET_ASM_INIT_SECTIONS
-Define this hook if you need to do something special to set up the
-@file{varasm.c} sections, or if your target has some special sections
-of its own that you need to create.
 
-GCC calls this hook after processing the command line, but before writing
-any assembly code, and before calling any of the section-returning hooks
-described below.
-@end deftypefn
-
 @hook TARGET_ASM_RELOC_RW_MASK
-Return a mask describing how relocations should be treated when
-selecting sections.  Bit 1 should be set if global relocations
-should be placed in a read-write section; bit 0 should be set if
-local relocations should be placed in a read-write section.
 
-The default version of this function returns 3 when @option{-fpic}
-is in effect, and 0 otherwise.  The hook is typically redefined
-when the target cannot support (some kinds of) dynamic relocations
-in read-only sections even in executables.
-@end deftypefn
-
 @hook TARGET_ASM_SELECT_SECTION
-Return the section into which @var{exp} should be placed.  You can
-assume that @var{exp} is either a @code{VAR_DECL} node or a constant of
-some sort.  @var{reloc} indicates whether the initial value of @var{exp}
-requires link-time relocations.  Bit 0 is set when variable contains
-local relocations only, while bit 1 is set for global relocations.
-@var{align} is the constant alignment in bits.
 
-The default version of this function takes care of putting read-only
-variables in @code{readonly_data_section}.
-
-See also @var{USE_SELECT_SECTION_FOR_FUNCTIONS}.
-@end deftypefn
-
 @defmac USE_SELECT_SECTION_FOR_FUNCTIONS
 Define this macro if you wish TARGET_ASM_SELECT_SECTION to be called
 for @code{FUNCTION_DECL}s as well as for variables and constants.
@@ -6970,122 +5224,30 @@ 
 @end defmac
 
 @hook TARGET_ASM_UNIQUE_SECTION
-Build up a unique section name, expressed as a @code{STRING_CST} node,
-and assign it to @samp{DECL_SECTION_NAME (@var{decl})}.
-As with @code{TARGET_ASM_SELECT_SECTION}, @var{reloc} indicates whether
-the initial value of @var{exp} requires link-time relocations.
 
-The default version of this function appends the symbol name to the
-ELF section name that would normally be used for the symbol.  For
-example, the function @code{foo} would be placed in @code{.text.foo}.
-Whatever the actual target object format, this is often good enough.
-@end deftypefn
-
 @hook TARGET_ASM_FUNCTION_RODATA_SECTION
-Return the readonly data section associated with
-@samp{DECL_SECTION_NAME (@var{decl})}.
-The default version of this function selects @code{.gnu.linkonce.r.name} if
-the function's section is @code{.gnu.linkonce.t.name}, @code{.rodata.name}
-if function is in @code{.text.name}, and the normal readonly-data section
-otherwise.
-@end deftypefn
 
 @hook TARGET_ASM_MERGEABLE_RODATA_PREFIX
 
 @hook TARGET_ASM_TM_CLONE_TABLE_SECTION
 
 @hook TARGET_ASM_SELECT_RTX_SECTION
-Return the section into which a constant @var{x}, of mode @var{mode},
-should be placed.  You can assume that @var{x} is some kind of
-constant in RTL@.  The argument @var{mode} is redundant except in the
-case of a @code{const_int} rtx.  @var{align} is the constant alignment
-in bits.
 
-The default version of this function takes care of putting symbolic
-constants in @code{flag_pic} mode in @code{data_section} and everything
-else in @code{readonly_data_section}.
-@end deftypefn
-
 @hook TARGET_MANGLE_DECL_ASSEMBLER_NAME
-Define this hook if you need to postprocess the assembler name generated
-by target-independent code.  The @var{id} provided to this hook will be
-the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C,
-or the mangled name of the @var{decl} in C++).  The return value of the
-hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on
-your target system.  The default implementation of this hook just
-returns the @var{id} provided.
-@end deftypefn
 
 @hook TARGET_ENCODE_SECTION_INFO
-Define this hook if references to a symbol or a constant must be
-treated differently depending on something about the variable or
-function named by the symbol (such as what section it is in).
 
-The hook is executed immediately after rtl has been created for
-@var{decl}, which may be a variable or function declaration or
-an entry in the constant pool.  In either case, @var{rtl} is the
-rtl in question.  Do @emph{not} use @code{DECL_RTL (@var{decl})}
-in this hook; that field may not have been initialized yet.
-
-In the case of a constant, it is safe to assume that the rtl is
-a @code{mem} whose address is a @code{symbol_ref}.  Most decls
-will also have this form, but that is not guaranteed.  Global
-register variables, for instance, will have a @code{reg} for their
-rtl.  (Normally the right thing to do with such unusual rtl is
-leave it alone.)
-
-The @var{new_decl_p} argument will be true if this is the first time
-that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl.  It will
-be false for subsequent invocations, which will happen for duplicate
-declarations.  Whether or not anything must be done for the duplicate
-declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}.
-@var{new_decl_p} is always true when the hook is called for a constant.
-
-@cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO}
-The usual thing for this hook to do is to record flags in the
-@code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}.
-Historically, the name string was modified if it was necessary to
-encode more than one bit of information, but this practice is now
-discouraged; use @code{SYMBOL_REF_FLAGS}.
-
-The default definition of this hook, @code{default_encode_section_info}
-in @file{varasm.c}, sets a number of commonly-useful bits in
-@code{SYMBOL_REF_FLAGS}.  Check whether the default does what you need
-before overriding it.
-@end deftypefn
-
 @hook TARGET_STRIP_NAME_ENCODING
-Decode @var{name} and return the real name part, sans
-the characters that @code{TARGET_ENCODE_SECTION_INFO}
-may have added.
-@end deftypefn
 
 @hook TARGET_IN_SMALL_DATA_P
-Returns true if @var{exp} should be placed into a ``small data'' section.
-The default version of this hook always returns false.
-@end deftypefn
 
 @hook TARGET_HAVE_SRODATA_SECTION
-Contains the value true if the target places read-only
-``small data'' into a separate section.  The default value is false.
-@end deftypevr
 
 @hook TARGET_PROFILE_BEFORE_PROLOGUE
 
 @hook TARGET_BINDS_LOCAL_P
-Returns true if @var{exp} names an object for which name resolution
-rules must resolve to the current ``module'' (dynamic shared library
-or executable image).
 
-The default version of this hook implements the name resolution rules
-for ELF, which has a looser model of global name binding than other
-currently supported object file formats.
-@end deftypefn
-
 @hook TARGET_HAVE_TLS
-Contains the value true if the target supports thread-local storage.
-The default value is false.
-@end deftypevr
 
 
 @node PIC
@@ -7166,39 +5328,12 @@ 
 
 @findex default_file_start
 @hook TARGET_ASM_FILE_START
-Output to @code{asm_out_file} any text which the assembler expects to
-find at the beginning of a file.  The default behavior is controlled
-by two flags, documented below.  Unless your target's assembler is
-quite unusual, if you override the default, you should call
-@code{default_file_start} at some point in your target hook.  This
-lets other target files rely on these variables.
-@end deftypefn
 
 @hook TARGET_ASM_FILE_START_APP_OFF
-If this flag is true, the text of the macro @code{ASM_APP_OFF} will be
-printed as the very first line in the assembly file, unless
-@option{-fverbose-asm} is in effect.  (If that macro has been defined
-to the empty string, this variable has no effect.)  With the normal
-definition of @code{ASM_APP_OFF}, the effect is to notify the GNU
-assembler that it need not bother stripping comments or extra
-whitespace from its input.  This allows it to work a bit faster.
 
-The default is false.  You should not set it to true unless you have
-verified that your port does not generate any extra whitespace or
-comments that will cause GAS to issue errors in NO_APP mode.
-@end deftypevr
-
 @hook TARGET_ASM_FILE_START_FILE_DIRECTIVE
-If this flag is true, @code{output_file_directive} will be called
-for the primary source file, immediately after printing
-@code{ASM_APP_OFF} (if that is enabled).  Most ELF assemblers expect
-this to be done.  The default is false.
-@end deftypevr
 
 @hook TARGET_ASM_FILE_END
-Output to @code{asm_out_file} any text which the assembler expects
-to find at the end of a file.  The default is to output nothing.
-@end deftypefn
 
 @deftypefun void file_end_indicate_exec_stack ()
 Some systems use a common convention, the @samp{.note.GNU-stack}
@@ -7210,24 +5345,10 @@ 
 @end deftypefun
 
 @hook TARGET_ASM_LTO_START
-Output to @code{asm_out_file} any text which the assembler expects
-to find at the start of an LTO section.  The default is to output
-nothing.
-@end deftypefn
 
 @hook TARGET_ASM_LTO_END
-Output to @code{asm_out_file} any text which the assembler expects
-to find at the end of an LTO section.  The default is to output
-nothing.
-@end deftypefn
 
 @hook TARGET_ASM_CODE_END
-Output to @code{asm_out_file} any text which is needed before emitting
-unwind info and debug info at the end of a file.  Some targets emit
-here PIC setup thunks that cannot be emitted at the end of file,
-because they couldn't have unwind info then.  The default is to output
-nothing.
-@end deftypefn
 
 @defmac ASM_COMMENT_START
 A C string constant describing how to begin a comment in the target
@@ -7272,22 +5393,8 @@ 
 @end defmac
 
 @hook TARGET_ASM_NAMED_SECTION
-Output assembly directives to switch to section @var{name}.  The section
-should have attributes as specified by @var{flags}, which is a bit mask
-of the @code{SECTION_*} flags defined in @file{output.h}.  If @var{decl}
-is non-NULL, it is the @code{VAR_DECL} or @code{FUNCTION_DECL} with which
-this section is associated.
-@end deftypefn
 
 @hook TARGET_ASM_FUNCTION_SECTION
-Return preferred text (sub)section for function @var{decl}.
-Main purpose of this function is to separate cold, normal and hot
-functions. @var{startup} is true when function is known to be used only
-at startup (from static constructors or it is @code{main()}).
-@var{exit} is true when function is known to be used only at exit
-(from static destructors).
-Return NULL if function should go to default text section.
-@end deftypefn
 
 @hook TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS
 
@@ -7298,74 +5405,12 @@ 
 
 @anchor{TARGET_HAVE_SWITCHABLE_BSS_SECTIONS}
 @hook TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
-This flag is true if we can create zeroed data by switching to a BSS
-section and then using @code{ASM_OUTPUT_SKIP} to allocate the space.
-This is true on most ELF targets.
-@end deftypevr
 
 @hook TARGET_SECTION_TYPE_FLAGS
-Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION}
-based on a variable or function decl, a section name, and whether or not the
-declaration's initializer may contain runtime relocations.  @var{decl} may be
-null, in which case read-write data should be assumed.
 
-The default version of this function handles choosing code vs data,
-read-only vs read-write data, and @code{flag_pic}.  You should only
-need to override this if your target has special flags that might be
-set via @code{__attribute__}.
-@end deftypefn
-
 @hook TARGET_ASM_RECORD_GCC_SWITCHES
-Provides the target with the ability to record the gcc command line
-switches that have been passed to the compiler, and options that are
-enabled.  The @var{type} argument specifies what is being recorded.
-It can take the following values:
 
-@table @gcctabopt
-@item SWITCH_TYPE_PASSED
-@var{text} is a command line switch that has been set by the user.
-
-@item SWITCH_TYPE_ENABLED
-@var{text} is an option which has been enabled.  This might be as a
-direct result of a command line switch, or because it is enabled by
-default or because it has been enabled as a side effect of a different
-command line switch.  For example, the @option{-O2} switch enables
-various different individual optimization passes.
-
-@item SWITCH_TYPE_DESCRIPTIVE
-@var{text} is either NULL or some descriptive text which should be
-ignored.  If @var{text} is NULL then it is being used to warn the
-target hook that either recording is starting or ending.  The first
-time @var{type} is SWITCH_TYPE_DESCRIPTIVE and @var{text} is NULL, the
-warning is for start up and the second time the warning is for
-wind down.  This feature is to allow the target hook to make any
-necessary preparations before it starts to record switches and to
-perform any necessary tidying up after it has finished recording
-switches.
-
-@item SWITCH_TYPE_LINE_START
-This option can be ignored by this target hook.
-
-@item  SWITCH_TYPE_LINE_END
-This option can be ignored by this target hook.
-@end table
-
-The hook's return value must be zero.  Other return values may be
-supported in the future.
-
-By default this hook is set to NULL, but an example implementation is
-provided for ELF based targets.  Called @var{elf_record_gcc_switches},
-it records the switches as ASCII text inside a new, string mergeable
-section in the assembler output file.  The name of the new section is
-provided by the @code{TARGET_ASM_RECORD_GCC_SWITCHES_SECTION} target
-hook.
-@end deftypefn
-
 @hook TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
-This is the name of the section that will be created by the example
-ELF implementation of the @code{TARGET_ASM_RECORD_GCC_SWITCHES} target
-hook.
-@end deftypevr
 
 @need 2000
 @node Data Output
@@ -7373,50 +5418,11 @@ 
 
 
 @hook TARGET_ASM_BYTE_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_HI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_SI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_DI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_TI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_HI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_SI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_DI_OP
-@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_TI_OP
-These hooks specify assembly directives for creating certain kinds
-of integer object.  The @code{TARGET_ASM_BYTE_OP} directive creates a
-byte-sized object, the @code{TARGET_ASM_ALIGNED_HI_OP} one creates an
-aligned two-byte object, and so on.  Any of the hooks may be
-@code{NULL}, indicating that no suitable directive is available.
 
-The compiler will print these strings at the start of a new line,
-followed immediately by the object's initial value.  In most cases,
-the string should contain a tab, a pseudo-op, and then another tab.
-@end deftypevr
-
 @hook TARGET_ASM_INTEGER
-The @code{assemble_integer} function uses this hook to output an
-integer object.  @var{x} is the object's value, @var{size} is its size
-in bytes and @var{aligned_p} indicates whether it is aligned.  The
-function should return @code{true} if it was able to output the
-object.  If it returns false, @code{assemble_integer} will try to
-split the object into smaller parts.
 
-The default implementation of this hook will use the
-@code{TARGET_ASM_BYTE_OP} family of strings, returning @code{false}
-when the relevant string is @code{NULL}.
-@end deftypefn
-
 @hook TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA
-A target hook to recognize @var{rtx} patterns that @code{output_addr_const}
-can't deal with, and output assembly code to @var{file} corresponding to
-the pattern @var{x}.  This may be used to allow machine-dependent
-@code{UNSPEC}s to appear within constants.
 
-If target hook fails to recognize a pattern, it must return @code{false},
-so that a standard error message is printed.  If it prints an error message
-itself, by calling, for example, @code{output_operand_lossage}, it may just
-return @code{true}.
-@end deftypefn
-
 @defmac ASM_OUTPUT_ASCII (@var{stream}, @var{ptr}, @var{len})
 A C statement to output to the stdio stream @var{stream} an assembler
 instruction to assemble a string constant containing the @var{len}
@@ -7505,10 +5511,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_OPEN_PAREN
-These target hooks are C string constants, describing the syntax in the
-assembler for grouping arithmetic expressions.  If not overridden, they
-default to normal parentheses, which is correct for most assemblers.
-@end deftypevr
 
 These macros are provided by @file{real.h} for writing the definitions
 of @code{ASM_OUTPUT_DOUBLE} and the like:
@@ -7798,19 +5800,7 @@ 
 @end defmac
 
 @hook TARGET_ASM_DECLARE_CONSTANT_NAME
-A target hook to output to the stdio stream @var{file} any text necessary
-for declaring the name @var{name} of a constant which is being defined.  This
-target hook is responsible for outputting the label definition (perhaps using
-@code{assemble_label}).  The argument @var{exp} is the value of the constant,
-and @var{size} is the size of the constant in bytes.  The @var{name}
-will be an internal label.
 
-The default version of this target hook, define the @var{name} in the
-usual manner as a label (by means of @code{assemble_label}).
-
-You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in this target hook.
-@end deftypefn
-
 @defmac ASM_DECLARE_REGISTER_GLOBAL (@var{stream}, @var{decl}, @var{regno}, @var{name})
 A C statement (sans semicolon) to output to the stdio stream
 @var{stream} any text necessary for claiming a register @var{regno}
@@ -7835,22 +5825,9 @@ 
 @end defmac
 
 @hook TARGET_ASM_GLOBALIZE_LABEL
-This target hook is a function to output to the stdio stream
-@var{stream} some commands that will make the label @var{name} global;
-that is, available for reference from other files.
 
-The default implementation relies on a proper definition of
-@code{GLOBAL_ASM_OP}.
-@end deftypefn
-
 @hook TARGET_ASM_GLOBALIZE_DECL_NAME
-This target hook is a function to output to the stdio stream
-@var{stream} some commands that will make the name associated with @var{decl}
-global; that is, available for reference from other files.
 
-The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
-@end deftypefn
-
 @defmac ASM_WEAKEN_LABEL (@var{stream}, @var{name})
 A C statement (sans semicolon) to output to the stdio stream
 @var{stream} some commands that will make the label @var{name} weak;
@@ -7921,10 +5898,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_ASSEMBLE_VISIBILITY
-This target hook is a function to output to @var{asm_out_file} some
-commands that will make the symbol(s) associated with @var{decl} have
-hidden, protected or internal visibility as specified by @var{visibility}.
-@end deftypefn
 
 @defmac TARGET_WEAK_NOT_IN_ARCHIVE_TOC
 A C expression that evaluates to true if the target's linker expects
@@ -7957,16 +5930,8 @@ 
 @end defmac
 
 @hook TARGET_ASM_EXTERNAL_LIBCALL
-This target hook is a function to output to @var{asm_out_file} an assembler
-pseudo-op to declare a library function name external.  The name of the
-library function is given by @var{symref}, which is a @code{symbol_ref}.
-@end deftypefn
 
 @hook TARGET_ASM_MARK_DECL_PRESERVED
-This target hook is a function to output to @var{asm_out_file} an assembler
-directive to annotate @var{symbol} as used.  The Darwin target uses the
-.no_dead_code_strip directive.
-@end deftypefn
 
 @defmac ASM_OUTPUT_LABELREF (@var{stream}, @var{name})
 A C statement (sans semicolon) to output to the stdio stream
@@ -7997,22 +5962,7 @@ 
 @end defmac
 
 @hook TARGET_ASM_INTERNAL_LABEL
-A function to output to the stdio stream @var{stream} a label whose
-name is made from the string @var{prefix} and the number @var{labelno}.
 
-It is absolutely essential that these labels be distinct from the labels
-used for user-level functions and variables.  Otherwise, certain programs
-will have name conflicts with internal labels.
-
-It is desirable to exclude internal labels from the symbol table of the
-object file.  Most assemblers have a naming convention for labels that
-should be excluded; on many systems, the letter @samp{L} at the
-beginning of a label has this effect.  You should find out what
-convention your system uses, and follow it.
-
-The default version of this function utilizes @code{ASM_GENERATE_INTERNAL_LABEL}.
-@end deftypefn
-
 @defmac ASM_OUTPUT_DEBUG_LABEL (@var{stream}, @var{prefix}, @var{num})
 A C statement to output to the stdio stream @var{stream} a debug info
 label whose name is made from the string @var{prefix} and the number
@@ -8322,30 +6272,10 @@ 
 @end defmac
 
 @hook TARGET_HAVE_CTORS_DTORS
-This value is true if the target supports some ``native'' method of
-collecting constructors and destructors to be run at startup and exit.
-It is false if we must use @command{collect2}.
-@end deftypevr
 
 @hook TARGET_ASM_CONSTRUCTOR
-If defined, a function that outputs assembler code to arrange to call
-the function referenced by @var{symbol} at initialization time.
 
-Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking
-no arguments and with no return value.  If the target supports initialization
-priorities, @var{priority} is a value between 0 and @code{MAX_INIT_PRIORITY};
-otherwise it must be @code{DEFAULT_INIT_PRIORITY}.
-
-If this macro is not defined by the target, a suitable default will
-be chosen if (1) the target supports arbitrary section names, (2) the
-target defines @code{CTORS_SECTION_ASM_OP}, or (3) @code{USE_COLLECT2}
-is not defined.
-@end deftypefn
-
 @hook TARGET_ASM_DESTRUCTOR
-This is like @code{TARGET_ASM_CONSTRUCTOR} but used for termination
-functions rather than initialization functions.
-@end deftypefn
 
 If @code{TARGET_HAVE_CTORS_DTORS} is true, the initialization routine
 generated for the generated object file will have static linkage.
@@ -8492,18 +6422,7 @@ 
 @end defmac
 
 @hook TARGET_ASM_FINAL_POSTSCAN_INSN
-If defined, this target hook is a function which is executed just after the
-output of assembler code for @var{insn}, to change the mode of the assembler
-if necessary.
 
-Here the argument @var{opvec} is the vector containing the operands
-extracted from @var{insn}, and @var{noperands} is the number of
-elements of the vector which contain meaningful data for this insn.
-The contents of this vector are what was used to convert the insn
-template into assembler code, so you can change the assembler mode
-by checking the contents of the vector.
-@end deftypefn
-
 @defmac PRINT_OPERAND (@var{stream}, @var{x}, @var{code})
 A C compound statement to output to stdio stream @var{stream} the
 assembler syntax for an instruction operand @var{x}.  @var{x} is an
@@ -8712,32 +6631,12 @@ 
 @end defmac
 
 @hook TARGET_ASM_EMIT_UNWIND_LABEL
-This target hook emits a label at the beginning of each FDE@.  It
-should be defined on targets where FDEs need special labels, and it
-should write the appropriate label, for the FDE associated with the
-function declaration @var{decl}, to the stdio stream @var{stream}.
-The third argument, @var{for_eh}, is a boolean: true if this is for an
-exception table.  The fourth argument, @var{empty}, is a boolean:
-true if this is a placeholder label for an omitted FDE@.
 
-The default is that FDEs are not given nonlocal labels.
-@end deftypefn
-
 @hook TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL
-This target hook emits a label at the beginning of the exception table.
-It should be defined on targets where it is desirable for the table
-to be broken up according to function.
 
-The default is that no label is emitted.
-@end deftypefn
-
 @hook TARGET_ASM_EMIT_EXCEPT_PERSONALITY
 
 @hook TARGET_ASM_UNWIND_EMIT
-This target hook emits assembly directives required to unwind the
-given instruction.  This is only used when @code{TARGET_EXCEPT_UNWIND_INFO}
-returns @code{UI_TARGET}.
-@end deftypefn
 
 @hook TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
 
@@ -8845,43 +6744,14 @@ 
 @end defmac
 
 @hook TARGET_TERMINATE_DW2_EH_FRAME_INFO
-Contains the value true if the target should add a zero word onto the
-end of a Dwarf-2 frame info section when used for exception handling.
-Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and
-true otherwise.
-@end deftypevr
 
 @hook TARGET_DWARF_REGISTER_SPAN
-Given a register, this hook should return a parallel of registers to
-represent where to find the register pieces.  Define this hook if the
-register and its mode are represented in Dwarf in non-contiguous
-locations, or if the register should be represented in more than one
-register in Dwarf.  Otherwise, this hook should return @code{NULL_RTX}.
-If not defined, the default is to return @code{NULL_RTX}.
-@end deftypefn
 
 @hook TARGET_INIT_DWARF_REG_SIZES_EXTRA
-If some registers are represented in Dwarf-2 unwind information in
-multiple pieces, define this hook to fill in information about the
-sizes of those pieces in the table used by the unwinder at runtime.
-It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after
-filling in a single size corresponding to each hard register;
-@var{address} is the address of the table.
-@end deftypefn
 
 @hook TARGET_ASM_TTYPE
-This hook is used to output a reference from a frame unwinding table to
-the type_info object identified by @var{sym}.  It should return @code{true}
-if the reference was output.  Returning @code{false} will cause the
-reference to be output using the normal Dwarf2 routines.
-@end deftypefn
 
 @hook TARGET_ARM_EABI_UNWINDER
-This flag should be set to @code{true} on targets that use an ARM EABI
-based unwinding library, and @code{false} on other targets.  This effects
-the format of unwinding tables, and how the unwinder in entered after
-running a cleanup.  The default is @code{false}.
-@end deftypevr
 
 @node Alignment Output
 @subsection Assembler Commands for Alignment
@@ -8904,10 +6774,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_JUMP_ALIGN_MAX_SKIP
-The maximum number of bytes to skip before @var{label} when applying
-@code{JUMP_ALIGN}.  This works only if
-@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
-@end deftypefn
 
 @defmac LABEL_ALIGN_AFTER_BARRIER (@var{label})
 The alignment (log base 2) to put in front of @var{label}, which follows
@@ -8919,10 +6785,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
-The maximum number of bytes to skip before @var{label} when applying
-@code{LABEL_ALIGN_AFTER_BARRIER}.  This works only if
-@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.
-@end deftypefn
 
 @defmac LOOP_ALIGN (@var{label})
 The alignment (log base 2) to put in front of @var{label} that heads
@@ -8939,10 +6801,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_LOOP_ALIGN_MAX_SKIP
-The maximum number of bytes to skip when applying @code{LOOP_ALIGN} to
-@var{label}.  This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is
-defined.
-@end deftypefn
 
 @defmac LABEL_ALIGN (@var{label})
 The alignment (log base 2) to put in front of @var{label}.
@@ -8956,10 +6814,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_LABEL_ALIGN_MAX_SKIP
-The maximum number of bytes to skip when applying @code{LABEL_ALIGN}
-to @var{label}.  This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN}
-is defined.
-@end deftypefn
 
 @defmac ASM_OUTPUT_SKIP (@var{stream}, @var{nbytes})
 A C statement to output to the stdio stream @var{stream} an assembler
@@ -9302,10 +7156,6 @@ 
 debugging output in response to the @option{-g} option.
 
 @hook TARGET_DWARF_CALLING_CONVENTION
-Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to
-be emitted for each function.  Instead of an integer return the enum
-value for the @code{DW_CC_} tag.
-@end deftypefn
 
 To support optional call frame debugging information, you must also
 define @code{INCOMING_RETURN_ADDR_RTX} and either set
@@ -9323,18 +7173,7 @@ 
 @end defmac
 
 @hook TARGET_DEBUG_UNWIND_INFO
-This hook defines the mechanism that will be used for describing frame
-unwind information to the debugger.  Normally the hook will return
-@code{UI_DWARF2} if DWARF 2 debug information is enabled, and
-return @code{UI_NONE} otherwise.
 
-A target may return @code{UI_DWARF2} even when DWARF 2 debug information
-is disabled in order to always output DWARF 2 frame information.
-
-A target may return @code{UI_TARGET} if it has ABI specified unwind tables.
-This will suppress generation of the normal debug frame unwind information.
-@end deftypefn
-
 @defmac DWARF2_ASM_LINE_DEBUG_INFO
 Define this macro to be a nonzero value if the assembler can generate Dwarf 2
 line debug info sections.  This will result in much more compact line number
@@ -9379,9 +7218,6 @@ 
 @end defmac
 
 @hook TARGET_ASM_OUTPUT_DWARF_DTPREL
-If defined, this target hook is a function which outputs a DTP-relative
-reference to the given TLS symbol of the specified size.
-@end deftypefn
 
 @defmac PUT_SDB_@dots{}
 Define these macros to override the assembler syntax for the special
@@ -9633,65 +7469,17 @@ 
 be documented in @file{extend.texi}.
 
 @hook TARGET_ATTRIBUTE_TABLE
-If defined, this target hook points to an array of @samp{struct
-attribute_spec} (defined in @file{tree.h}) specifying the machine
-specific attributes for this target and some of the restrictions on the
-entities to which these attributes are applied and the arguments they
-take.
-@end deftypevr
 
 @hook TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P
-If defined, this target hook is a function which returns true if the
-machine-specific attribute named @var{name} expects an identifier
-given as its first argument to be passed on as a plain identifier, not
-subjected to name lookup.  If this is not defined, the default is
-false for all machine-specific attributes.
-@end deftypefn
 
 @hook TARGET_COMP_TYPE_ATTRIBUTES
-If defined, this target hook is a function which returns zero if the attributes on
-@var{type1} and @var{type2} are incompatible, one if they are compatible,
-and two if they are nearly compatible (which causes a warning to be
-generated).  If this is not defined, machine-specific attributes are
-supposed always to be compatible.
-@end deftypefn
 
 @hook TARGET_SET_DEFAULT_TYPE_ATTRIBUTES
-If defined, this target hook is a function which assigns default attributes to
-the newly defined @var{type}.
-@end deftypefn
 
 @hook TARGET_MERGE_TYPE_ATTRIBUTES
-Define this target hook if the merging of type attributes needs special
-handling.  If defined, the result is a list of the combined
-@code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}.  It is assumed
-that @code{comptypes} has already been called and returned 1.  This
-function may call @code{merge_attributes} to handle machine-independent
-merging.
-@end deftypefn
 
 @hook TARGET_MERGE_DECL_ATTRIBUTES
-Define this target hook if the merging of decl attributes needs special
-handling.  If defined, the result is a list of the combined
-@code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}.
-@var{newdecl} is a duplicate declaration of @var{olddecl}.  Examples of
-when this is needed are when one attribute overrides another, or when an
-attribute is nullified by a subsequent definition.  This function may
-call @code{merge_attributes} to handle machine-independent merging.
 
-@findex TARGET_DLLIMPORT_DECL_ATTRIBUTES
-If the only target-specific handling you require is @samp{dllimport}
-for Microsoft Windows targets, you should define the macro
-@code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}.  The compiler
-will then define a function called
-@code{merge_dllimport_decl_attributes} which can then be defined as
-the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}.  You can also
-add @code{handle_dll_attribute} in the attribute table for your port
-to perform initial processing of the @samp{dllimport} and
-@samp{dllexport} attributes.  This is done in @file{i386/cygwin.h} and
-@file{i386/i386.c}, for example.
-@end deftypefn
-
 @hook TARGET_VALID_DLLIMPORT_ATTRIBUTE_P
 
 @defmac TARGET_DECLSPEC
@@ -9704,92 +7492,24 @@ 
 @end defmac
 
 @hook TARGET_INSERT_ATTRIBUTES
-Define this target hook if you want to be able to add attributes to a decl
-when it is being created.  This is normally useful for back ends which
-wish to implement a pragma by using the attributes which correspond to
-the pragma's effect.  The @var{node} argument is the decl which is being
-created.  The @var{attr_ptr} argument is a pointer to the attribute list
-for this decl.  The list itself should not be modified, since it may be
-shared with other decls, but attributes may be chained on the head of
-the list and @code{*@var{attr_ptr}} modified to point to the new
-attributes, or a copy of the list may be made if further changes are
-needed.
-@end deftypefn
 
 @hook TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P
-@cindex inlining
-This target hook returns @code{true} if it is ok to inline @var{fndecl}
-into the current function, despite its having target-specific
-attributes, @code{false} otherwise.  By default, if a function has a
-target specific attribute attached to it, it will not be inlined.
-@end deftypefn
 
 @hook TARGET_OPTION_VALID_ATTRIBUTE_P
-This hook is called to parse @code{attribute(target("..."))}, which
-allows setting target-specific options on individual functions.
-These function-specific options may differ
-from the options specified on the command line.  The hook should return
-@code{true} if the options are valid.
 
-The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in
-the function declaration to hold a pointer to a target-specific
-@code{struct cl_target_option} structure.
-@end deftypefn
-
 @hook TARGET_OPTION_SAVE
-This hook is called to save any additional target-specific information
-in the @code{struct cl_target_option} structure for function-specific
-options.
-@xref{Option file format}.
-@end deftypefn
 
 @hook TARGET_OPTION_RESTORE
-This hook is called to restore any additional target-specific
-information in the @code{struct cl_target_option} structure for
-function-specific options.
-@end deftypefn
 
 @hook TARGET_OPTION_PRINT
-This hook is called to print any additional target-specific
-information in the @code{struct cl_target_option} structure for
-function-specific options.
-@end deftypefn
 
 @hook TARGET_OPTION_PRAGMA_PARSE
-This target hook parses the options for @code{#pragma GCC target}, which
-sets the target-specific options for functions that occur later in the
-input stream.  The options accepted should be the same as those handled by the
-@code{TARGET_OPTION_VALID_ATTRIBUTE_P} hook.
-@end deftypefn
 
 @hook TARGET_OPTION_OVERRIDE
-Sometimes certain combinations of command options do not make sense on
-a particular target machine.  You can override the hook
-@code{TARGET_OPTION_OVERRIDE} to take account of this.  This hooks is called
-once just after all the command options have been parsed.
 
-Don't use this hook to turn on various extra optimizations for
-@option{-O}.  That is what @code{TARGET_OPTION_OPTIMIZATION} is for.
-
-If you need to do something whenever the optimization level is
-changed via the optimize attribute or pragma, see
-@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}
-@end deftypefn
-
 @hook TARGET_OPTION_FUNCTION_VERSIONS
-This target hook returns @code{true} if @var{DECL1} and @var{DECL2} are
-versions of the same function.  @var{DECL1} and @var{DECL2} are function
-versions if and only if they have the same function signature and
-different target specific attributes, that is, they are compiled for
-different target machines.
-@end deftypefn
 
 @hook TARGET_CAN_INLINE_P
-This target hook returns @code{false} if the @var{caller} function
-cannot inline @var{callee}, based on target specific information.  By
-default, inlining is not allowed if the callee function has function
-specific target options and the caller does not use the same options.
-@end deftypefn
 
 @node Emulated TLS
 @section Emulating TLS
@@ -9808,66 +7528,24 @@ 
 address of the current thread's instance of the TLS object.
 
 @hook TARGET_EMUTLS_GET_ADDRESS
-Contains the name of the helper function that uses a TLS control
-object to locate a TLS instance.  The default causes libgcc's
-emulated TLS helper function to be used.
-@end deftypevr
 
 @hook TARGET_EMUTLS_REGISTER_COMMON
-Contains the name of the helper function that should be used at
-program startup to register TLS objects that are implicitly
-initialized to zero.  If this is @code{NULL}, all TLS objects will
-have explicit initializers.  The default causes libgcc's emulated TLS
-registration function to be used.
-@end deftypevr
 
 @hook TARGET_EMUTLS_VAR_SECTION
-Contains the name of the section in which TLS control variables should
-be placed.  The default of @code{NULL} allows these to be placed in
-any section.
-@end deftypevr
 
 @hook TARGET_EMUTLS_TMPL_SECTION
-Contains the name of the section in which TLS initializers should be
-placed.  The default of @code{NULL} allows these to be placed in any
-section.
-@end deftypevr
 
 @hook TARGET_EMUTLS_VAR_PREFIX
-Contains the prefix to be prepended to TLS control variable names.
-The default of @code{NULL} uses a target-specific prefix.
-@end deftypevr
 
 @hook TARGET_EMUTLS_TMPL_PREFIX
-Contains the prefix to be prepended to TLS initializer objects.  The
-default of @code{NULL} uses a target-specific prefix.
-@end deftypevr
 
 @hook TARGET_EMUTLS_VAR_FIELDS
-Specifies a function that generates the FIELD_DECLs for a TLS control
-object type.  @var{type} is the RECORD_TYPE the fields are for and
-@var{name} should be filled with the structure tag, if the default of
-@code{__emutls_object} is unsuitable.  The default creates a type suitable
-for libgcc's emulated TLS function.
-@end deftypefn
 
 @hook TARGET_EMUTLS_VAR_INIT
-Specifies a function that generates the CONSTRUCTOR to initialize a
-TLS control object.  @var{var} is the TLS control object, @var{decl}
-is the TLS object and @var{tmpl_addr} is the address of the
-initializer.  The default initializes libgcc's emulated TLS control object.
-@end deftypefn
 
 @hook TARGET_EMUTLS_VAR_ALIGN_FIXED
-Specifies whether the alignment of TLS control variable objects is
-fixed and should not be increased as some backends may do to optimize
-single objects.  The default is false.
-@end deftypevr
 
 @hook TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
-Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor
-may be used to describe emulated TLS control objects.
-@end deftypevr
 
 @node MIPS Coprocessors
 @section Defining coprocessor specifics for MIPS targets.
@@ -9905,33 +7583,10 @@ 
 @cindex parameters, precompiled headers
 
 @hook TARGET_GET_PCH_VALIDITY
-This hook returns a pointer to the data needed by
-@code{TARGET_PCH_VALID_P} and sets
-@samp{*@var{sz}} to the size of the data in bytes.
-@end deftypefn
 
 @hook TARGET_PCH_VALID_P
-This hook checks whether the options used to create a PCH file are
-compatible with the current settings.  It returns @code{NULL}
-if so and a suitable error message if not.  Error messages will
-be presented to the user and must be localized using @samp{_(@var{msg})}.
 
-@var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY}
-when the PCH file was created and @var{sz} is the size of that data in bytes.
-It's safe to assume that the data was created by the same version of the
-compiler, so no format checking is needed.
-
-The default definition of @code{default_pch_valid_p} should be
-suitable for most targets.
-@end deftypefn
-
 @hook TARGET_CHECK_PCH_TARGET_FLAGS
-If this hook is nonnull, the default implementation of
-@code{TARGET_PCH_VALID_P} will use it to check for compatible values
-of @code{target_flags}.  @var{pch_flags} specifies the value that
-@code{target_flags} had when the PCH file was created.  The return
-value is the same as for @code{TARGET_PCH_VALID_P}.
-@end deftypefn
 
 @hook TARGET_PREPARE_PCH_SAVE
 
@@ -9940,84 +7595,28 @@ 
 @cindex parameters, c++ abi
 
 @hook TARGET_CXX_GUARD_TYPE
-Define this hook to override the integer type used for guard variables.
-These are used to implement one-time construction of static objects.  The
-default is long_long_integer_type_node.
-@end deftypefn
 
 @hook TARGET_CXX_GUARD_MASK_BIT
-This hook determines how guard variables are used.  It should return
-@code{false} (the default) if the first byte should be used.  A return value of
-@code{true} indicates that only the least significant bit should be used.
-@end deftypefn
 
 @hook TARGET_CXX_GET_COOKIE_SIZE
-This hook returns the size of the cookie to use when allocating an array
-whose elements have the indicated @var{type}.  Assumes that it is already
-known that a cookie is needed.  The default is
-@code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the
-IA64/Generic C++ ABI@.
-@end deftypefn
 
 @hook TARGET_CXX_COOKIE_HAS_SIZE
-This hook should return @code{true} if the element size should be stored in
-array cookies.  The default is to return @code{false}.
-@end deftypefn
 
 @hook TARGET_CXX_IMPORT_EXPORT_CLASS
-If defined by a backend this hook allows the decision made to export
-class @var{type} to be overruled.  Upon entry @var{import_export}
-will contain 1 if the class is going to be exported, @minus{}1 if it is going
-to be imported and 0 otherwise.  This function should return the
-modified value and perform any other actions necessary to support the
-backend's targeted operating system.
-@end deftypefn
 
 @hook TARGET_CXX_CDTOR_RETURNS_THIS
-This hook should return @code{true} if constructors and destructors return
-the address of the object created/destroyed.  The default is to return
-@code{false}.
-@end deftypefn
 
 @hook TARGET_CXX_KEY_METHOD_MAY_BE_INLINE
-This hook returns true if the key method for a class (i.e., the method
-which, if defined in the current translation unit, causes the virtual
-table to be emitted) may be an inline function.  Under the standard
-Itanium C++ ABI the key method may be an inline function so long as
-the function is not declared inline in the class definition.  Under
-some variants of the ABI, an inline function can never be the key
-method.  The default is to return @code{true}.
-@end deftypefn
 
 @hook TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY
 
 @hook TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT
-This hook returns true (the default) if virtual tables and other
-similar implicit class data objects are always COMDAT if they have
-external linkage.  If this hook returns false, then class data for
-classes whose virtual table will be emitted in only one translation
-unit will not be COMDAT.
-@end deftypefn
 
 @hook TARGET_CXX_LIBRARY_RTTI_COMDAT
-This hook returns true (the default) if the RTTI information for
-the basic types which is defined in the C++ runtime should always
-be COMDAT, false if it should not be COMDAT.
-@end deftypefn
 
 @hook TARGET_CXX_USE_AEABI_ATEXIT
-This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI)
-should be used to register static destructors when @option{-fuse-cxa-atexit}
-is in effect.  The default is to return false to use @code{__cxa_atexit}.
-@end deftypefn
 
 @hook TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT
-This hook returns true if the target @code{atexit} function can be used
-in the same manner as @code{__cxa_atexit} to register C++ static
-destructors. This requires that @code{atexit}-registered functions in
-shared libraries are run in the correct order when the libraries are
-unloaded. The default is to return false.
-@end deftypefn
 
 @hook TARGET_CXX_ADJUST_CLASS_AT_DEFINITION
 
@@ -10062,62 +7661,18 @@ 
 @end smallexample
 
 @hook TARGET_ADDR_SPACE_POINTER_MODE
-Define this to return the machine mode to use for pointers to
-@var{address_space} if the target supports named address spaces.
-The default version of this hook returns @code{ptr_mode} for the
-generic address space only.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_ADDRESS_MODE
-Define this to return the machine mode to use for addresses in
-@var{address_space} if the target supports named address spaces.
-The default version of this hook returns @code{Pmode} for the
-generic address space only.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_VALID_POINTER_MODE
-Define this to return nonzero if the port can handle pointers
-with machine mode @var{mode} to address space @var{as}.  This target
-hook is the same as the @code{TARGET_VALID_POINTER_MODE} target hook,
-except that it includes explicit named address space support.  The default
-version of this hook returns true for the modes returned by either the
-@code{TARGET_ADDR_SPACE_POINTER_MODE} or @code{TARGET_ADDR_SPACE_ADDRESS_MODE}
-target hooks for the given address space.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P
-Define this to return true if @var{exp} is a valid address for mode
-@var{mode} in the named address space @var{as}.  The @var{strict}
-parameter says whether strict addressing is in effect after reload has
-finished.  This target hook is the same as the
-@code{TARGET_LEGITIMATE_ADDRESS_P} target hook, except that it includes
-explicit named address space support.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS
-Define this to modify an invalid address @var{x} to be a valid address
-with mode @var{mode} in the named address space @var{as}.  This target
-hook is the same as the @code{TARGET_LEGITIMIZE_ADDRESS} target hook,
-except that it includes explicit named address space support.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_SUBSET_P
-Define this to return whether the @var{subset} named address space is
-contained within the @var{superset} named address space.  Pointers to
-a named address space that is a subset of another named address space
-will be converted automatically without a cast if used together in
-arithmetic operations.  Pointers to a superset address space can be
-converted to pointers to a subset address space via explicit casts.
-@end deftypefn
 
 @hook TARGET_ADDR_SPACE_CONVERT
-Define this to convert the pointer expression represented by the RTL
-@var{op} with type @var{from_type} that points to a named address
-space to a new pointer expression with type @var{to_type} that points
-to a different named address space.  When this hook it called, it is
-guaranteed that one of the two address spaces is a subset of the other,
-as determined by the @code{TARGET_ADDR_SPACE_SUBSET_P} target hook.
-@end deftypefn
 
 @node Misc
 @section Miscellaneous Parameters
@@ -10168,11 +7723,6 @@ 
 @end defmac
 
 @hook TARGET_CASE_VALUES_THRESHOLD
-This function return the smallest number of different values for which it
-is best to use a jump-table instead of a tree of conditional branches.
-The default is four for machines with a @code{casesi} instruction and
-five otherwise.  This is best for most machines.
-@end deftypefn
 
 @defmac WORD_REGISTER_OPERATIONS
 Define this macro if operations between registers with integral mode
@@ -10213,13 +7763,6 @@ 
 @end defmac
 
 @hook TARGET_MIN_DIVISIONS_FOR_RECIP_MUL
-When @option{-ffast-math} is in effect, GCC tries to optimize
-divisions by the same divisor, by turning them into multiplications by
-the reciprocal.  This target hook specifies the minimum number of divisions
-that should be there for GCC to perform the optimization for a variable
-of mode @var{mode}.  The default implementation returns 3 if the machine
-has an instruction for the division, and 2 if it does not.
-@end deftypefn
 
 @defmac MOVE_MAX
 The maximum number of bytes that a single instruction can move quickly
@@ -10261,29 +7804,7 @@ 
 
 @anchor{TARGET_SHIFT_TRUNCATION_MASK}
 @hook TARGET_SHIFT_TRUNCATION_MASK
-This function describes how the standard shift patterns for @var{mode}
-deal with shifts by negative amounts or by more than the width of the mode.
-@xref{shift patterns}.
 
-On many machines, the shift patterns will apply a mask @var{m} to the
-shift count, meaning that a fixed-width shift of @var{x} by @var{y} is
-equivalent to an arbitrary-width shift of @var{x} by @var{y & m}.  If
-this is true for mode @var{mode}, the function should return @var{m},
-otherwise it should return 0.  A return value of 0 indicates that no
-particular behavior is guaranteed.
-
-Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does
-@emph{not} apply to general shift rtxes; it applies only to instructions
-that are generated by the named shift patterns.
-
-The default implementation of this function returns
-@code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED}
-and 0 otherwise.  This definition is always safe, but if
-@code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns
-nevertheless truncate the shift count, you may get better code
-by overriding it.
-@end deftypefn
-
 @defmac TRULY_NOOP_TRUNCATION (@var{outprec}, @var{inprec})
 A C expression which is nonzero if on this machine it is safe to
 ``convert'' an integer of @var{inprec} bits to one of @var{outprec}
@@ -10301,33 +7822,7 @@ 
 @end defmac
 
 @hook TARGET_MODE_REP_EXTENDED
-The representation of an integral mode can be such that the values
-are always extended to a wider integral mode.  Return
-@code{SIGN_EXTEND} if values of @var{mode} are represented in
-sign-extended form to @var{rep_mode}.  Return @code{UNKNOWN}
-otherwise.  (Currently, none of the targets use zero-extended
-representation this way so unlike @code{LOAD_EXTEND_OP},
-@code{TARGET_MODE_REP_EXTENDED} is expected to return either
-@code{SIGN_EXTEND} or @code{UNKNOWN}.  Also no target extends
-@var{mode} to @var{rep_mode} so that @var{rep_mode} is not the next
-widest integral mode and currently we take advantage of this fact.)
 
-Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN}
-value even if the extension is not performed on certain hard registers
-as long as for the @code{REGNO_REG_CLASS} of these hard registers
-@code{CANNOT_CHANGE_MODE_CLASS} returns nonzero.
-
-Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP}
-describe two related properties.  If you define
-@code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want
-to define @code{LOAD_EXTEND_OP (mode)} to return the same type of
-extension.
-
-In order to enforce the representation of @code{mode},
-@code{TRULY_NOOP_TRUNCATION} should return false when truncating to
-@code{mode}.
-@end deftypefn
-
 @defmac STORE_FLAG_VALUE
 A C expression describing the value returned by a comparison operator
 with an integral mode and stored by a store-flag instruction
@@ -10629,15 +8124,6 @@ 
 @end defmac
 
 @hook TARGET_MD_ASM_CLOBBERS
-This target hook should add to @var{clobbers} @code{STRING_CST} trees for
-any hard regs the port wishes to automatically clobber for an asm.
-It should return the result of the last @code{tree_cons} used to add a
-clobber.  The @var{outputs}, @var{inputs} and @var{clobber} lists are the
-corresponding parameters to the asm and may be inspected to avoid
-clobbering a register that is an input or output of the asm.  You can use
-@code{tree_overlaps_hard_reg_set}, declared in @file{tree.h}, to test
-for overlap with regards to asm-declared registers.
-@end deftypefn
 
 @defmac MATH_LIBRARY
 Define this macro as a C string constant for the linker argument to link
@@ -10718,119 +8204,27 @@ 
 @end defmac
 
 @hook TARGET_MACHINE_DEPENDENT_REORG
-If non-null, this hook performs a target-specific pass over the
-instruction stream.  The compiler will run it at all optimization levels,
-just before the point at which it normally does delayed-branch scheduling.
 
-The exact purpose of the hook varies from target to target.  Some use
-it to do transformations that are necessary for correctness, such as
-laying out in-function constant pools or avoiding hardware hazards.
-Others use it as an opportunity to do some machine-dependent optimizations.
-
-You need not implement the hook if it has nothing to do.  The default
-definition is null.
-@end deftypefn
-
 @hook TARGET_INIT_BUILTINS
-Define this hook if you have any machine-specific built-in functions
-that need to be defined.  It should be a function that performs the
-necessary setup.
 
-Machine specific built-in functions can be useful to expand special machine
-instructions that would otherwise not normally be generated because
-they have no equivalent in the source language (for example, SIMD vector
-instructions or prefetch instructions).
-
-To create a built-in function, call the function
-@code{lang_hooks.builtin_function}
-which is defined by the language front end.  You can use any type nodes set
-up by @code{build_common_tree_nodes};
-only language front ends that use those two functions will call
-@samp{TARGET_INIT_BUILTINS}.
-@end deftypefn
-
 @hook TARGET_BUILTIN_DECL
-Define this hook if you have any machine-specific built-in functions
-that need to be defined.  It should be a function that returns the
-builtin function declaration for the builtin function code @var{code}.
-If there is no such builtin and it cannot be initialized at this time
-if @var{initialize_p} is true the function should return @code{NULL_TREE}.
-If @var{code} is out of range the function should return
-@code{error_mark_node}.
-@end deftypefn
 
 @hook TARGET_EXPAND_BUILTIN
 
-Expand a call to a machine specific built-in function that was set up by
-@samp{TARGET_INIT_BUILTINS}.  @var{exp} is the expression for the
-function call; the result should go to @var{target} if that is
-convenient, and have mode @var{mode} if that is convenient.
-@var{subtarget} may be used as the target for computing one of
-@var{exp}'s operands.  @var{ignore} is nonzero if the value is to be
-ignored.  This function should return the result of the call to the
-built-in function.
-@end deftypefn
-
 @hook TARGET_RESOLVE_OVERLOADED_BUILTIN
-Select a replacement for a machine specific built-in function that
-was set up by @samp{TARGET_INIT_BUILTINS}.  This is done
-@emph{before} regular type checking, and so allows the target to
-implement a crude form of function overloading.  @var{fndecl} is the
-declaration of the built-in function.  @var{arglist} is the list of
-arguments passed to the built-in function.  The result is a
-complete expression that implements the operation, usually
-another @code{CALL_EXPR}.
-@var{arglist} really has type @samp{VEC(tree,gc)*}
-@end deftypefn
 
 @hook TARGET_FOLD_BUILTIN
-Fold a call to a machine specific built-in function that was set up by
-@samp{TARGET_INIT_BUILTINS}.  @var{fndecl} is the declaration of the
-built-in function.  @var{n_args} is the number of arguments passed to
-the function; the arguments themselves are pointed to by @var{argp}.
-The result is another tree, valid for both GIMPLE and GENERIC,
-containing a simplified expression for the call's result.  If
-@var{ignore} is true the value will be ignored.
-@end deftypefn
 
 @hook TARGET_GIMPLE_FOLD_BUILTIN
 
 @hook TARGET_COMPARE_VERSION_PRIORITY
-This hook is used to compare the target attributes in two functions to
-determine which function's features get higher priority.  This is used
-during function multi-versioning to figure out the order in which two
-versions must be dispatched.  A function version with a higher priority
-is checked for dispatching earlier.  @var{decl1} and @var{decl2} are
- the two function decls that will be compared.
-@end deftypefn
 
 @hook TARGET_GET_FUNCTION_VERSIONS_DISPATCHER
-This hook is used to get the dispatcher function for a set of function
-versions.  The dispatcher function is called to invoke the right function
-version at run-time. @var{decl} is one version from a set of semantically
-identical versions.
-@end deftypefn
 
 @hook TARGET_GENERATE_VERSION_DISPATCHER_BODY
-This hook is used to generate the dispatcher logic to invoke the right
-function version at run-time for a given set of function versions.
-@var{arg} points to the callgraph node of the dispatcher function whose
-body must be generated.
-@end deftypefn
 
 @hook TARGET_INVALID_WITHIN_DOLOOP
 
-Take an instruction in @var{insn} and return NULL if it is valid within a
-low-overhead loop, otherwise return a string explaining why doloop
-could not be applied.
-
-Many targets use special registers for low-overhead looping. For any
-instruction that clobbers these this function should return a string indicating
-the reason why the doloop could not be applied.
-By default, the RTL loop optimizer does not use a present doloop pattern for
-loops containing function calls or branch on table instructions.
-@end deftypefn
-
 @hook TARGET_LEGITIMATE_COMBINED_INSN
 
 @defmac MD_CAN_REDIRECT_BRANCH (@var{branch1}, @var{branch2})
@@ -10847,62 +8241,13 @@ 
 @hook TARGET_CAN_FOLLOW_JUMP
 
 @hook TARGET_COMMUTATIVE_P
-This target hook returns @code{true} if @var{x} is considered to be commutative.
-Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider
-PLUS to be commutative inside a MEM@.  @var{outer_code} is the rtx code
-of the enclosing rtl, if known, otherwise it is UNKNOWN.
-@end deftypefn
 
 @hook TARGET_ALLOCATE_INITIAL_VALUE
 
-When the initial value of a hard register has been copied in a pseudo
-register, it is often not necessary to actually allocate another register
-to this pseudo register, because the original hard register or a stack slot
-it has been saved into can be used.  @code{TARGET_ALLOCATE_INITIAL_VALUE}
-is called at the start of register allocation once for each hard register
-that had its initial value copied by using
-@code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}.
-Possible values are @code{NULL_RTX}, if you don't want
-to do any special allocation, a @code{REG} rtx---that would typically be
-the hard register itself, if it is known not to be clobbered---or a
-@code{MEM}.
-If you are returning a @code{MEM}, this is only a hint for the allocator;
-it might decide to use another register anyways.
-You may use @code{current_function_is_leaf} or 
-@code{REG_N_SETS} in the hook to determine if the hard
-register in question will not be clobbered.
-The default value of this hook is @code{NULL}, which disables any special
-allocation.
-@end deftypefn
-
 @hook TARGET_UNSPEC_MAY_TRAP_P
-This target hook returns nonzero if @var{x}, an @code{unspec} or
-@code{unspec_volatile} operation, might cause a trap.  Targets can use
-this hook to enhance precision of analysis for @code{unspec} and
-@code{unspec_volatile} operations.  You may call @code{may_trap_p_1}
-to analyze inner elements of @var{x} in which case @var{flags} should be
-passed along.
-@end deftypefn
 
 @hook TARGET_SET_CURRENT_FUNCTION
-The compiler invokes this hook whenever it changes its current function
-context (@code{cfun}).  You can define this function if
-the back end needs to perform any initialization or reset actions on a
-per-function basis.  For example, it may be used to implement function
-attributes that affect register usage or code generation patterns.
-The argument @var{decl} is the declaration for the new function context,
-and may be null to indicate that the compiler has left a function context
-and is returning to processing at the top level.
-The default hook function does nothing.
 
-GCC sets @code{cfun} to a dummy function context during initialization of
-some parts of the back end.  The hook function is not invoked in this
-situation; you need not worry about the hook being invoked recursively,
-or when the back end is in a partially-initialized state.
-@code{cfun} might be @code{NULL} to indicate processing at top level,
-outside of any function scope.
-@end deftypefn
-
 @defmac TARGET_OBJECT_SUFFIX
 Define this macro to be a C string representing the suffix for object
 files on your target machine.  If you do not define this macro, GCC will
@@ -10941,56 +8286,14 @@ 
 @end defmac
 
 @hook TARGET_CANNOT_MODIFY_JUMPS_P
-This target hook returns @code{true} past the point in which new jump
-instructions could be created.  On machines that require a register for
-every jump such as the SHmedia ISA of SH5, this point would typically be
-reload, so this target hook should be defined to a function such as:
 
-@smallexample
-static bool
-cannot_modify_jumps_past_reload_p ()
-@{
-  return (reload_completed || reload_in_progress);
-@}
-@end smallexample
-@end deftypefn
-
 @hook TARGET_BRANCH_TARGET_REGISTER_CLASS
-This target hook returns a register class for which branch target register
-optimizations should be applied.  All registers in this class should be
-usable interchangeably.  After reload, registers in this class will be
-re-allocated and loads will be hoisted out of loops and be subjected
-to inter-block scheduling.
-@end deftypefn
 
 @hook TARGET_BRANCH_TARGET_REGISTER_CALLEE_SAVED
-Branch target register optimization will by default exclude callee-saved
-registers
-that are not already live during the current function; if this target hook
-returns true, they will be included.  The target code must than make sure
-that all target registers in the class returned by
-@samp{TARGET_BRANCH_TARGET_REGISTER_CLASS} that might need saving are
-saved.  @var{after_prologue_epilogue_gen} indicates if prologues and
-epilogues have already been generated.  Note, even if you only return
-true when @var{after_prologue_epilogue_gen} is false, you still are likely
-to have to make special provisions in @code{INITIAL_ELIMINATION_OFFSET}
-to reserve space for caller-saved target registers.
-@end deftypefn
 
 @hook TARGET_HAVE_CONDITIONAL_EXECUTION
-This target hook returns true if the target supports conditional execution.
-This target hook is required only when the target has several different
-modes and they have different conditional execution capability, such as ARM.
-@end deftypefn
 
 @hook TARGET_LOOP_UNROLL_ADJUST
-This target hook returns a new value for the number of times @var{loop}
-should be unrolled. The parameter @var{nunroll} is the number of times
-the loop is to be unrolled. The parameter @var{loop} is a pointer to
-the loop, which is going to be checked for unrolling. This target hook
-is required only when the target has special constraints like maximum
-number of memory accesses.
-@end deftypefn
 
 @defmac POWI_MAX_MULTS
 If defined, this macro is interpreted as a signed integer C expression
@@ -11062,72 +8365,22 @@ 
 @end defmac
 
 @hook TARGET_RELAXED_ORDERING
-If set to @code{true}, means that the target's memory model does not
-guarantee that loads which do not depend on one another will access
-main memory in the order of the instruction stream; if ordering is
-important, an explicit memory barrier must be used.  This is true of
-many recent processors which implement a policy of ``relaxed,''
-``weak,'' or ``release'' memory consistency, such as Alpha, PowerPC,
-and ia64.  The default is @code{false}.
-@end deftypevr
 
 @hook TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN
-If defined, this macro returns the diagnostic message when it is
-illegal to pass argument @var{val} to function @var{funcdecl}
-with prototype @var{typelist}.
-@end deftypefn
 
 @hook TARGET_INVALID_CONVERSION
-If defined, this macro returns the diagnostic message when it is
-invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL}
-if validity should be determined by the front end.
-@end deftypefn
 
 @hook TARGET_INVALID_UNARY_OP
-If defined, this macro returns the diagnostic message when it is
-invalid to apply operation @var{op} (where unary plus is denoted by
-@code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL}
-if validity should be determined by the front end.
-@end deftypefn
 
 @hook TARGET_INVALID_BINARY_OP
-If defined, this macro returns the diagnostic message when it is
-invalid to apply operation @var{op} to operands of types @var{type1}
-and @var{type2}, or @code{NULL} if validity should be determined by
-the front end.
-@end deftypefn
 
 @hook TARGET_INVALID_PARAMETER_TYPE
-If defined, this macro returns the diagnostic message when it is
-invalid for functions to include parameters of type @var{type},
-or @code{NULL} if validity should be determined by
-the front end.  This is currently used only by the C and C++ front ends.
-@end deftypefn
 
 @hook TARGET_INVALID_RETURN_TYPE
-If defined, this macro returns the diagnostic message when it is
-invalid for functions to have return type @var{type},
-or @code{NULL} if validity should be determined by
-the front end.  This is currently used only by the C and C++ front ends.
-@end deftypefn
 
 @hook TARGET_PROMOTED_TYPE
-If defined, this target hook returns the type to which values of
-@var{type} should be promoted when they appear in expressions,
-analogous to the integer promotions, or @code{NULL_TREE} to use the
-front end's normal promotion rules.  This hook is useful when there are
-target-specific types with special promotion rules.
-This is currently used only by the C and C++ front ends.
-@end deftypefn
 
 @hook TARGET_CONVERT_TO_TYPE
-If defined, this hook returns the result of converting @var{expr} to
-@var{type}.  It should return the converted expression,
-or @code{NULL_TREE} to apply the front end's normal conversion rules.
-This hook is useful when there are target-specific types with special
-conversion rules.
-This is currently used only by the C and C++ front ends.
-@end deftypefn
 
 @defmac TARGET_USE_JCR_SECTION
 This macro determines whether to use the JCR section to register Java
@@ -11148,52 +8401,16 @@ 
 @end defmac
 
 @hook TARGET_UPDATE_STACK_BOUNDARY
-Define this macro to update the current function stack boundary if
-necessary.
-@end deftypefn
 
 @hook TARGET_GET_DRAP_RTX
-This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
-different argument pointer register is needed to access the function's
-argument list due to stack realignment.  Return @code{NULL} if no DRAP
-is needed.
-@end deftypefn
 
 @hook TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS
-When optimization is disabled, this hook indicates whether or not
-arguments should be allocated to stack slots.  Normally, GCC allocates
-stacks slots for arguments when not optimizing in order to make
-debugging easier.  However, when a function is declared with
-@code{__attribute__((naked))}, there is no stack frame, and the compiler
-cannot safely move arguments from the registers in which they are passed
-to the stack.  Therefore, this hook should return true in general, but
-false for naked functions.  The default implementation always returns true.
-@end deftypefn
 
 @hook TARGET_CONST_ANCHOR
-On some architectures it can take multiple instructions to synthesize
-a constant.  If there is another constant already in a register that
-is close enough in value then it is preferable that the new constant
-is computed from this register using immediate addition or
-subtraction.  We accomplish this through CSE.  Besides the value of
-the constant we also add a lower and an upper constant anchor to the
-available expressions.  These are then queried when encountering new
-constants.  The anchors are computed by rounding the constant up and
-down to a multiple of the value of @code{TARGET_CONST_ANCHOR}.
-@code{TARGET_CONST_ANCHOR} should be the maximum positive value
-accepted by immediate-add plus one.  We currently assume that the
-value of @code{TARGET_CONST_ANCHOR} is a power of 2.  For example, on
-MIPS, where add-immediate takes a 16-bit signed value,
-@code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}.  The default value
-is zero, which disables this optimization.
-@end deftypevr
 
 @hook TARGET_ASAN_SHADOW_OFFSET
 
 @hook TARGET_MEMMODEL_CHECK
-Validate target specific memory model mask bits. When NULL no target specific
-memory model bits are allowed.
-@end deftypefn
 
 @hook TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
 
Index: target.def
===================================================================
--- target.def	(revision 200891)
+++ target.def	(working copy)
@@ -35,14 +35,32 @@ 
 /* Opening and closing parentheses for asm expression grouping.  */
 DEFHOOKPOD
 (open_paren,
- "",
+ "These target hooks are C string constants, describing the syntax in the\n\
+assembler for grouping arithmetic expressions.  If not overridden, they\n\
+default to normal parentheses, which is correct for most assemblers.",
  const char *, "(")
 DEFHOOKPODX (close_paren, const char *, ")")
 
 /* Assembler instructions for creating various kinds of integer object.  */
 DEFHOOKPOD
 (byte_op,
- "",
+ "@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_HI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_SI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_DI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_TI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_HI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_SI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_DI_OP\n\
+@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_TI_OP\n\
+These hooks specify assembly directives for creating certain kinds\n\
+of integer object.  The @code{TARGET_ASM_BYTE_OP} directive creates a\n\
+byte-sized object, the @code{TARGET_ASM_ALIGNED_HI_OP} one creates an\n\
+aligned two-byte object, and so on.  Any of the hooks may be\n\
+@code{NULL}, indicating that no suitable directive is available.\n\
+\n\
+The compiler will print these strings at the start of a new line,\n\
+followed immediately by the object's initial value.  In most cases,\n\
+the string should contain a tab, a pseudo-op, and then another tab.",
  const char *, "\t.byte\t")
 DEFHOOKPOD (aligned_op, "*", struct asm_int_op, TARGET_ASM_ALIGNED_INT_OP)
 DEFHOOKPOD (unaligned_op, "*", struct asm_int_op, TARGET_ASM_UNALIGNED_INT_OP)
@@ -51,7 +69,9 @@ 
    LABEL_ALIGN_AFTER_BARRIER.  */
 DEFHOOK
 (label_align_after_barrier_max_skip,
- "",
+ "The maximum number of bytes to skip before @var{label} when applying\n\
+@code{LABEL_ALIGN_AFTER_BARRIER}.  This works only if\n\
+@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.",
  int, (rtx label),
  default_label_align_after_barrier_max_skip)
 
@@ -59,7 +79,9 @@ 
    LOOP_ALIGN.  */
 DEFHOOK
 (loop_align_max_skip,
- "",
+ "The maximum number of bytes to skip when applying @code{LOOP_ALIGN} to\n\
+@var{label}.  This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is\n\
+defined.",
  int, (rtx label),
  default_loop_align_max_skip)
 
@@ -67,7 +89,9 @@ 
    LABEL_ALIGN.  */
 DEFHOOK
 (label_align_max_skip,
- "",
+ "The maximum number of bytes to skip when applying @code{LABEL_ALIGN}\n\
+to @var{label}.  This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN}\n\
+is defined.",
  int, (rtx label),
  default_label_align_max_skip)
 
@@ -75,7 +99,9 @@ 
    JUMP_ALIGN.  */
 DEFHOOK
 (jump_align_max_skip,
- "",
+ "The maximum number of bytes to skip before @var{label} when applying\n\
+@code{JUMP_ALIGN}.  This works only if\n\
+@code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined.",
  int, (rtx label),
  default_jump_align_max_skip)
 
@@ -86,7 +112,16 @@ 
    and UNALIGNED_OP are NULL.  */
 DEFHOOK
 (integer,
- "",
+ "The @code{assemble_integer} function uses this hook to output an\n\
+integer object.  @var{x} is the object's value, @var{size} is its size\n\
+in bytes and @var{aligned_p} indicates whether it is aligned.  The\n\
+function should return @code{true} if it was able to output the\n\
+object.  If it returns false, @code{assemble_integer} will try to\n\
+split the object into smaller parts.\n\
+\n\
+The default implementation of this hook will use the\n\
+@code{TARGET_ASM_BYTE_OP} family of strings, returning @code{false}\n\
+when the relevant string is @code{NULL}.",
  /* Only handles cases for which BYTE_OP, ALIGNED_OP and UNALIGNED_OP are
     NULL.  */
  bool, (rtx x, unsigned int size, int aligned_p),
@@ -95,14 +130,23 @@ 
 /* Output code that will globalize a label.  */
 DEFHOOK
 (globalize_label,
- "",
+ "This target hook is a function to output to the stdio stream\n\
+@var{stream} some commands that will make the label @var{name} global;\n\
+that is, available for reference from other files.\n\
+\n\
+The default implementation relies on a proper definition of\n\
+@code{GLOBAL_ASM_OP}.",
  void, (FILE *stream, const char *name),
  default_globalize_label)
 
 /* Output code that will globalize a declaration.  */
 DEFHOOK
 (globalize_decl_name,
- "",
+ "This target hook is a function to output to the stdio stream\n\
+@var{stream} some commands that will make the name associated with @var{decl}\n\
+global; that is, available for reference from other files.\n\
+\n\
+The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.",
  void, (FILE *stream, tree decl), default_globalize_decl_name)
 
 /* Output code that will emit a label for unwind info, if this
@@ -112,14 +156,26 @@ 
    this is only a placeholder for an omitted FDE.  */
 DEFHOOK
 (emit_unwind_label,
- "",
+ "This target hook emits a label at the beginning of each FDE@.  It\n\
+should be defined on targets where FDEs need special labels, and it\n\
+should write the appropriate label, for the FDE associated with the\n\
+function declaration @var{decl}, to the stdio stream @var{stream}.\n\
+The third argument, @var{for_eh}, is a boolean: true if this is for an\n\
+exception table.  The fourth argument, @var{empty}, is a boolean:\n\
+true if this is a placeholder label for an omitted FDE@.\n\
+\n\
+The default is that FDEs are not given nonlocal labels.",
  void, (FILE *stream, tree decl, int for_eh, int empty),
  default_emit_unwind_label)
 
 /* Output code that will emit a label to divide up the exception table.  */
 DEFHOOK
 (emit_except_table_label,
- "",
+ "This target hook emits a label at the beginning of the exception table.\n\
+It should be defined on targets where it is desirable for the table\n\
+to be broken up according to function.\n\
+\n\
+The default is that no label is emitted.",
  void, (FILE *stream),
  default_emit_except_table_label)
 
@@ -135,7 +191,9 @@ 
 /* Emit any directives required to unwind this instruction.  */
 DEFHOOK
 (unwind_emit,
- "",
+ "This target hook emits assembly directives required to unwind the\n\
+given instruction.  This is only used when @code{TARGET_EXCEPT_UNWIND_INFO}\n\
+returns @code{UI_TARGET}.",
  void, (FILE *stream, rtx insn),
  NULL)
 
@@ -157,21 +215,47 @@ 
 /* Output an internal label.  */
 DEFHOOK
 (internal_label,
- "",
+ "A function to output to the stdio stream @var{stream} a label whose\n\
+name is made from the string @var{prefix} and the number @var{labelno}.\n\
+\n\
+It is absolutely essential that these labels be distinct from the labels\n\
+used for user-level functions and variables.  Otherwise, certain programs\n\
+will have name conflicts with internal labels.\n\
+\n\
+It is desirable to exclude internal labels from the symbol table of the\n\
+object file.  Most assemblers have a naming convention for labels that\n\
+should be excluded; on many systems, the letter @samp{L} at the\n\
+beginning of a label has this effect.  You should find out what\n\
+convention your system uses, and follow it.\n\
+\n\
+The default version of this function utilizes @code{ASM_GENERATE_INTERNAL_LABEL}.",
  void, (FILE *stream, const char *prefix, unsigned long labelno),
  default_internal_label)
 
 /* Output label for the constant.  */
 DEFHOOK
 (declare_constant_name,
- "",
+ "A target hook to output to the stdio stream @var{file} any text necessary\n\
+for declaring the name @var{name} of a constant which is being defined.  This\n\
+target hook is responsible for outputting the label definition (perhaps using\n\
+@code{assemble_label}).  The argument @var{exp} is the value of the constant,\n\
+and @var{size} is the size of the constant in bytes.  The @var{name}\n\
+will be an internal label.\n\
+\n\
+The default version of this target hook, define the @var{name} in the\n\
+usual manner as a label (by means of @code{assemble_label}).\n\
+\n\
+You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in this target hook.",
  void, (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size),
  default_asm_declare_constant_name)
 
 /* Emit a ttype table reference to a typeinfo object.  */
 DEFHOOK
 (ttype,
- "",
+ "This hook is used to output a reference from a frame unwinding table to\n\
+the type_info object identified by @var{sym}.  It should return @code{true}\n\
+if the reference was output.  Returning @code{false} will cause the\n\
+reference to be output using the normal Dwarf2 routines.",
  bool, (rtx sym),
  hook_bool_rtx_false)
 
@@ -179,42 +263,140 @@ 
    associated with the tree decl.  */
 DEFHOOK
 (assemble_visibility,
- "",
+ "This target hook is a function to output to @var{asm_out_file} some\n\
+commands that will make the symbol(s) associated with @var{decl} have\n\
+hidden, protected or internal visibility as specified by @var{visibility}.",
  void, (tree decl, int visibility),
  default_assemble_visibility)
 
 /* Output the assembler code for entry to a function.  */
 DEFHOOK
 (function_prologue,
- "",
+ "If defined, a function that outputs the assembler code for entry to a\n\
+function.  The prologue is responsible for setting up the stack frame,\n\
+initializing the frame pointer register, saving registers that must be\n\
+saved, and allocating @var{size} additional bytes of storage for the\n\
+local variables.  @var{size} is an integer.  @var{file} is a stdio\n\
+stream to which the assembler code should be output.\n\
+\n\
+The label for the beginning of the function need not be output by this\n\
+macro.  That has already been done when the macro is run.\n\
+\n\
+@findex regs_ever_live\n\
+To determine which registers to save, the macro can refer to the array\n\
+@code{regs_ever_live}: element @var{r} is nonzero if hard register\n\
+@var{r} is used anywhere within the function.  This implies the function\n\
+prologue should save register @var{r}, provided it is not one of the\n\
+call-used registers.  (@code{TARGET_ASM_FUNCTION_EPILOGUE} must likewise use\n\
+@code{regs_ever_live}.)\n\
+\n\
+On machines that have ``register windows'', the function entry code does\n\
+not save on the stack the registers that are in the windows, even if\n\
+they are supposed to be preserved by function calls; instead it takes\n\
+appropriate steps to ``push'' the register stack, if any non-call-used\n\
+registers are used in the function.\n\
+\n\
+@findex frame_pointer_needed\n\
+On machines where functions may or may not have frame-pointers, the\n\
+function entry code must vary accordingly; it must set up the frame\n\
+pointer if one is wanted, and not otherwise.  To determine whether a\n\
+frame pointer is in wanted, the macro can refer to the variable\n\
+@code{frame_pointer_needed}.  The variable's value will be 1 at run\n\
+time in a function that needs a frame pointer.  @xref{Elimination}.\n\
+\n\
+The function entry code is responsible for allocating any stack space\n\
+required for the function.  This stack space consists of the regions\n\
+listed below.  In most cases, these regions are allocated in the\n\
+order listed, with the last listed region closest to the top of the\n\
+stack (the lowest address if @code{STACK_GROWS_DOWNWARD} is defined, and\n\
+the highest address if it is not defined).  You can use a different order\n\
+for a machine if doing so is more convenient or required for\n\
+compatibility reasons.  Except in cases where required by standard\n\
+or by a debugger, there is no reason why the stack layout used by GCC\n\
+need agree with that used by other compilers for a machine.",
  void, (FILE *file, HOST_WIDE_INT size),
  default_function_pro_epilogue)
 
 /* Output the assembler code for end of prologue.  */
 DEFHOOK
 (function_end_prologue,
- "",
+ "If defined, a function that outputs assembler code at the end of a\n\
+prologue.  This should be used when the function prologue is being\n\
+emitted as RTL, and you have some extra assembler that needs to be\n\
+emitted.  @xref{prologue instruction pattern}.",
  void, (FILE *file),
  no_asm_to_stream)
 
 /* Output the assembler code for start of epilogue.  */
 DEFHOOK
 (function_begin_epilogue,
- "",
+ "If defined, a function that outputs assembler code at the start of an\n\
+epilogue.  This should be used when the function epilogue is being\n\
+emitted as RTL, and you have some extra assembler that needs to be\n\
+emitted.  @xref{epilogue instruction pattern}.",
  void, (FILE *file),
  no_asm_to_stream)
 
 /* Output the assembler code for function exit.  */
 DEFHOOK
 (function_epilogue,
- "",
+ "If defined, a function that outputs the assembler code for exit from a\n\
+function.  The epilogue is responsible for restoring the saved\n\
+registers and stack pointer to their values when the function was\n\
+called, and returning control to the caller.  This macro takes the\n\
+same arguments as the macro @code{TARGET_ASM_FUNCTION_PROLOGUE}, and the\n\
+registers to restore are determined from @code{regs_ever_live} and\n\
+@code{CALL_USED_REGISTERS} in the same way.\n\
+\n\
+On some machines, there is a single instruction that does all the work\n\
+of returning from the function.  On these machines, give that\n\
+instruction the name @samp{return} and do not define the macro\n\
+@code{TARGET_ASM_FUNCTION_EPILOGUE} at all.\n\
+\n\
+Do not define a pattern named @samp{return} if you want the\n\
+@code{TARGET_ASM_FUNCTION_EPILOGUE} to be used.  If you want the target\n\
+switches to control whether return instructions or epilogues are used,\n\
+define a @samp{return} pattern with a validity condition that tests the\n\
+target switches appropriately.  If the @samp{return} pattern's validity\n\
+condition is false, epilogues will be used.\n\
+\n\
+On machines where functions may or may not have frame-pointers, the\n\
+function exit code must vary accordingly.  Sometimes the code for these\n\
+two cases is completely different.  To determine whether a frame pointer\n\
+is wanted, the macro can refer to the variable\n\
+@code{frame_pointer_needed}.  The variable's value will be 1 when compiling\n\
+a function that needs a frame pointer.\n\
+\n\
+Normally, @code{TARGET_ASM_FUNCTION_PROLOGUE} and\n\
+@code{TARGET_ASM_FUNCTION_EPILOGUE} must treat leaf functions specially.\n\
+The C variable @code{current_function_is_leaf} is nonzero for such a\n\
+function.  @xref{Leaf Functions}.\n\
+\n\
+On some machines, some functions pop their arguments on exit while\n\
+others leave that for the caller to do.  For example, the 68020 when\n\
+given @option{-mrtd} pops arguments in functions that take a fixed\n\
+number of arguments.\n\
+\n\
+@findex pops_args\n\
+@findex crtl->args.pops_args\n\
+Your definition of the macro @code{RETURN_POPS_ARGS} decides which\n\
+functions pop their own arguments.  @code{TARGET_ASM_FUNCTION_EPILOGUE}\n\
+needs to know what was decided.  The number of bytes of the current\n\
+function's arguments that this function should pop is available in\n\
+@code{crtl->args.pops_args}.  @xref{Scalar Return}.",
  void, (FILE *file, HOST_WIDE_INT size),
  default_function_pro_epilogue)
 
 /* Initialize target-specific sections.  */
 DEFHOOK
 (init_sections,
- "",
+ "Define this hook if you need to do something special to set up the\n\
+@file{varasm.c} sections, or if your target has some special sections\n\
+of its own that you need to create.\n\
+\n\
+GCC calls this hook after processing the command line, but before writing\n\
+any assembly code, and before calling any of the section-returning hooks\n\
+described below.",
  void, (void),
  hook_void_void)
 
@@ -223,7 +405,11 @@ 
    which this section is associated.  */
 DEFHOOK
 (named_section,
- "",
+ "Output assembly directives to switch to section @var{name}.  The section\n\
+should have attributes as specified by @var{flags}, which is a bit mask\n\
+of the @code{SECTION_*} flags defined in @file{output.h}.  If @var{decl}\n\
+is non-NULL, it is the @code{VAR_DECL} or @code{FUNCTION_DECL} with which\n\
+this section is associated.",
  void, (const char *name, unsigned int flags, tree decl),
  default_no_named_section)
 
@@ -236,7 +422,13 @@ 
    Return NULL if function should go to default text section.  */
 DEFHOOK
 (function_section,
- "",
+ "Return preferred text (sub)section for function @var{decl}.\n\
+Main purpose of this function is to separate cold, normal and hot\n\
+functions. @var{startup} is true when function is known to be used only\n\
+at startup (from static constructors or it is @code{main()}).\n\
+@var{exit} is true when function is known to be used only at exit\n\
+(from static destructors).\n\
+Return NULL if function should go to default text section.",
  section *, (tree decl, enum node_frequency freq, bool startup, bool exit),
  default_function_section)
 
@@ -257,7 +449,15 @@ 
    local relocations should be placed in a read-write section.  */
 DEFHOOK
 (reloc_rw_mask,
- "",
+ "Return a mask describing how relocations should be treated when\n\
+selecting sections.  Bit 1 should be set if global relocations\n\
+should be placed in a read-write section; bit 0 should be set if\n\
+local relocations should be placed in a read-write section.\n\
+\n\
+The default version of this function returns 3 when @option{-fpic}\n\
+is in effect, and 0 otherwise.  The hook is typically redefined\n\
+when the target cannot support (some kinds of) dynamic relocations\n\
+in read-only sections even in executables.",
  int, (void),
  default_reloc_rw_mask)
 
@@ -267,7 +467,17 @@ 
     ALIGN is the required alignment of the data.  */
 DEFHOOK
 (select_section,
- "",
+ "Return the section into which @var{exp} should be placed.  You can\n\
+assume that @var{exp} is either a @code{VAR_DECL} node or a constant of\n\
+some sort.  @var{reloc} indicates whether the initial value of @var{exp}\n\
+requires link-time relocations.  Bit 0 is set when variable contains\n\
+local relocations only, while bit 1 is set for global relocations.\n\
+@var{align} is the constant alignment in bits.\n\
+\n\
+The default version of this function takes care of putting read-only\n\
+variables in @code{readonly_data_section}.\n\
+\n\
+See also @var{USE_SELECT_SECTION_FOR_FUNCTIONS}.",
  section *, (tree exp, int reloc, unsigned HOST_WIDE_INT align),
  default_select_section)
 
@@ -275,7 +485,15 @@ 
    alignment in bits.  */
 DEFHOOK
 (select_rtx_section,
- "",
+ "Return the section into which a constant @var{x}, of mode @var{mode},\n\
+should be placed.  You can assume that @var{x} is some kind of\n\
+constant in RTL@.  The argument @var{mode} is redundant except in the\n\
+case of a @code{const_int} rtx.  @var{align} is the constant alignment\n\
+in bits.\n\
+\n\
+The default version of this function takes care of putting symbolic\n\
+constants in @code{flag_pic} mode in @code{data_section} and everything\n\
+else in @code{readonly_data_section}.",
  section *, (enum machine_mode mode, rtx x, unsigned HOST_WIDE_INT align),
  default_select_rtx_section)
 
@@ -283,14 +501,27 @@ 
    for SELECT_SECTION.  */
 DEFHOOK
 (unique_section,
- "",
+ "Build up a unique section name, expressed as a @code{STRING_CST} node,\n\
+and assign it to @samp{DECL_SECTION_NAME (@var{decl})}.\n\
+As with @code{TARGET_ASM_SELECT_SECTION}, @var{reloc} indicates whether\n\
+the initial value of @var{exp} requires link-time relocations.\n\
+\n\
+The default version of this function appends the symbol name to the\n\
+ELF section name that would normally be used for the symbol.  For\n\
+example, the function @code{foo} would be placed in @code{.text.foo}.\n\
+Whatever the actual target object format, this is often good enough.",
  void, (tree decl, int reloc),
  default_unique_section)
 
 /* Return the readonly data section associated with function DECL.  */
 DEFHOOK
 (function_rodata_section,
- "",
+ "Return the readonly data section associated with\n\
+@samp{DECL_SECTION_NAME (@var{decl})}.\n\
+The default version of this function selects @code{.gnu.linkonce.r.name} if\n\
+the function's section is @code{.gnu.linkonce.t.name}, @code{.rodata.name}\n\
+if function is in @code{.text.name}, and the normal readonly-data section\n\
+otherwise.",
  section *, (tree decl),
  default_function_rodata_section)
 
@@ -313,13 +544,25 @@ 
 /* Output a constructor for a symbol with a given priority.  */
 DEFHOOK
 (constructor,
- "",
+ "If defined, a function that outputs assembler code to arrange to call\n\
+the function referenced by @var{symbol} at initialization time.\n\
+\n\
+Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking\n\
+no arguments and with no return value.  If the target supports initialization\n\
+priorities, @var{priority} is a value between 0 and @code{MAX_INIT_PRIORITY};\n\
+otherwise it must be @code{DEFAULT_INIT_PRIORITY}.\n\
+\n\
+If this macro is not defined by the target, a suitable default will\n\
+be chosen if (1) the target supports arbitrary section names, (2) the\n\
+target defines @code{CTORS_SECTION_ASM_OP}, or (3) @code{USE_COLLECT2}\n\
+is not defined.",
  void, (rtx symbol, int priority), NULL)
 
 /* Output a destructor for a symbol with a given priority.  */
 DEFHOOK
 (destructor,
- "",
+ "This is like @code{TARGET_ASM_CONSTRUCTOR} but used for termination\n\
+functions rather than initialization functions.",
  void, (rtx symbol, int priority), NULL)
 
 /* Output the assembler code for a thunk function.  THUNK_DECL is the
@@ -329,7 +572,45 @@ 
    *(*this + vcall_offset) should be added to THIS.  */
 DEFHOOK
 (output_mi_thunk,
- "",
+ "A function that outputs the assembler code for a thunk\n\
+function, used to implement C++ virtual function calls with multiple\n\
+inheritance.  The thunk acts as a wrapper around a virtual function,\n\
+adjusting the implicit object parameter before handing control off to\n\
+the real function.\n\
+\n\
+First, emit code to add the integer @var{delta} to the location that\n\
+contains the incoming first argument.  Assume that this argument\n\
+contains a pointer, and is the one used to pass the @code{this} pointer\n\
+in C++.  This is the incoming argument @emph{before} the function prologue,\n\
+e.g.@: @samp{%o0} on a sparc.  The addition must preserve the values of\n\
+all other incoming arguments.\n\
+\n\
+Then, if @var{vcall_offset} is nonzero, an additional adjustment should be\n\
+made after adding @code{delta}.  In particular, if @var{p} is the\n\
+adjusted pointer, the following adjustment should be made:\n\
+\n\
+@smallexample\n\
+p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]\n\
+@end smallexample\n\
+\n\
+After the additions, emit code to jump to @var{function}, which is a\n\
+@code{FUNCTION_DECL}.  This is a direct pure jump, not a call, and does\n\
+not touch the return address.  Hence returning from @var{FUNCTION} will\n\
+return to whoever called the current @samp{thunk}.\n\
+\n\
+The effect must be as if @var{function} had been called directly with\n\
+the adjusted first argument.  This macro is responsible for emitting all\n\
+of the code for a thunk function; @code{TARGET_ASM_FUNCTION_PROLOGUE}\n\
+and @code{TARGET_ASM_FUNCTION_EPILOGUE} are not invoked.\n\
+\n\
+The @var{thunk_fndecl} is redundant.  (@var{delta} and @var{function}\n\
+have already been extracted from it.)  It might possibly be useful on\n\
+some targets, but probably not.\n\
+\n\
+If you do not define this macro, the target-independent code in the C++\n\
+front end will generate a less efficient heavyweight thunk that calls\n\
+@var{function} instead of jumping to it.  The generic approach does\n\
+not support varargs.",
  void, (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
 	HOST_WIDE_INT vcall_offset, tree function),
  NULL)
@@ -342,7 +623,11 @@ 
    text to the output file.  */
 DEFHOOK
 (can_output_mi_thunk,
- "",
+ "A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able\n\
+to output the assembler code for the thunk function specified by the\n\
+arguments it is passed, and false otherwise.  In the latter case, the\n\
+generic approach will be used by the C++ front end, with the limitations\n\
+previously exposed.",
  bool, (const_tree thunk_fndecl, HOST_WIDE_INT delta,
 	HOST_WIDE_INT vcall_offset, const_tree function),
  hook_bool_const_tree_hwi_hwi_const_tree_false)
@@ -351,14 +636,20 @@ 
    translation unit.  */
 DEFHOOK
 (file_start,
- "",
+ "Output to @code{asm_out_file} any text which the assembler expects to\n\
+find at the beginning of a file.  The default behavior is controlled\n\
+by two flags, documented below.  Unless your target's assembler is\n\
+quite unusual, if you override the default, you should call\n\
+@code{default_file_start} at some point in your target hook.  This\n\
+lets other target files rely on these variables.",
  void, (void),
  default_file_start)
 
 /* Output any boilerplate text needed at the end of a translation unit.  */
 DEFHOOK
 (file_end,
- "",
+ "Output to @code{asm_out_file} any text which the assembler expects\n\
+to find at the end of a file.  The default is to output nothing.",
  void, (void),
  hook_void_void)
 
@@ -366,7 +657,9 @@ 
    LTO output stream.  */
 DEFHOOK
 (lto_start,
- "",
+ "Output to @code{asm_out_file} any text which the assembler expects\n\
+to find at the start of an LTO section.  The default is to output\n\
+nothing.",
  void, (void),
  hook_void_void)
 
@@ -374,7 +667,9 @@ 
    LTO output stream.  */
 DEFHOOK
 (lto_end,
- "",
+ "Output to @code{asm_out_file} any text which the assembler expects\n\
+to find at the end of an LTO section.  The default is to output\n\
+nothing.",
  void, (void),
  hook_void_void)
 
@@ -382,7 +677,11 @@ 
    translation unit before debug and unwind info is emitted.  */
 DEFHOOK
 (code_end,
- "",
+ "Output to @code{asm_out_file} any text which is needed before emitting\n\
+unwind info and debug info at the end of a file.  Some targets emit\n\
+here PIC setup thunks that cannot be emitted at the end of file,\n\
+because they couldn't have unwind info then.  The default is to output\n\
+nothing.",
  void, (void),
  hook_void_void)
 
@@ -390,7 +689,9 @@ 
    external.  */
 DEFHOOK
 (external_libcall,
- "",
+ "This target hook is a function to output to @var{asm_out_file} an assembler\n\
+pseudo-op to declare a library function name external.  The name of the\n\
+library function is given by @var{symref}, which is a @code{symbol_ref}.",
  void, (rtx symref),
  default_external_libcall)
 
@@ -398,14 +699,58 @@ 
    linker to not dead code strip this symbol.  */
 DEFHOOK
 (mark_decl_preserved,
- "",
+ "This target hook is a function to output to @var{asm_out_file} an assembler\n\
+directive to annotate @var{symbol} as used.  The Darwin target uses the\n\
+.no_dead_code_strip directive.",
  void, (const char *symbol),
  hook_void_constcharptr)
 
 /* Output a record of the command line switches that have been passed.  */
 DEFHOOK
 (record_gcc_switches,
- "",
+ "Provides the target with the ability to record the gcc command line\n\
+switches that have been passed to the compiler, and options that are\n\
+enabled.  The @var{type} argument specifies what is being recorded.\n\
+It can take the following values:\n\
+\n\
+@table @gcctabopt\n\
+@item SWITCH_TYPE_PASSED\n\
+@var{text} is a command line switch that has been set by the user.\n\
+\n\
+@item SWITCH_TYPE_ENABLED\n\
+@var{text} is an option which has been enabled.  This might be as a\n\
+direct result of a command line switch, or because it is enabled by\n\
+default or because it has been enabled as a side effect of a different\n\
+command line switch.  For example, the @option{-O2} switch enables\n\
+various different individual optimization passes.\n\
+\n\
+@item SWITCH_TYPE_DESCRIPTIVE\n\
+@var{text} is either NULL or some descriptive text which should be\n\
+ignored.  If @var{text} is NULL then it is being used to warn the\n\
+target hook that either recording is starting or ending.  The first\n\
+time @var{type} is SWITCH_TYPE_DESCRIPTIVE and @var{text} is NULL, the\n\
+warning is for start up and the second time the warning is for\n\
+wind down.  This feature is to allow the target hook to make any\n\
+necessary preparations before it starts to record switches and to\n\
+perform any necessary tidying up after it has finished recording\n\
+switches.\n\
+\n\
+@item SWITCH_TYPE_LINE_START\n\
+This option can be ignored by this target hook.\n\
+\n\
+@item  SWITCH_TYPE_LINE_END\n\
+This option can be ignored by this target hook.\n\
+@end table\n\
+\n\
+The hook's return value must be zero.  Other return values may be\n\
+supported in the future.\n\
+\n\
+By default this hook is set to NULL, but an example implementation is\n\
+provided for ELF based targets.  Called @var{elf_record_gcc_switches},\n\
+it records the switches as ASCII text inside a new, string mergeable\n\
+section in the assembler output file.  The name of the new section is\n\
+provided by the @code{TARGET_ASM_RECORD_GCC_SWITCHES_SECTION} target\n\
+hook.",
  int, (print_switch_type type, const char *text),
  NULL)
 
@@ -415,13 +760,23 @@ 
    this information.  */
 DEFHOOKPOD
 (record_gcc_switches_section,
- "",
+ "This is the name of the section that will be created by the example\n\
+ELF implementation of the @code{TARGET_ASM_RECORD_GCC_SWITCHES} target\n\
+hook.",
  const char *, ".GCC.command.line")
 
 /* Output the definition of a section anchor.  */
 DEFHOOK
 (output_anchor,
- "",
+ "Write the assembly code to define section anchor @var{x}, which is a\n\
+@code{SYMBOL_REF} for which @samp{SYMBOL_REF_ANCHOR_P (@var{x})} is true.\n\
+The hook is called with the assembly output position set to the beginning\n\
+of @code{SYMBOL_REF_BLOCK (@var{x})}.\n\
+\n\
+If @code{ASM_OUTPUT_DEF} is available, the hook's default definition uses\n\
+it to define the symbol as @samp{. + SYMBOL_REF_BLOCK_OFFSET (@var{x})}.\n\
+If @code{ASM_OUTPUT_DEF} is not available, the hook's default definition\n\
+is @code{NULL}, which disables the use of section anchors altogether.",
  void, (rtx x),
  default_asm_output_anchor)
 
@@ -437,21 +792,39 @@ 
 /* Output a DTP-relative reference to a TLS symbol.  */
 DEFHOOK
 (output_dwarf_dtprel,
- "",
+ "If defined, this target hook is a function which outputs a DTP-relative\n\
+reference to the given TLS symbol of the specified size.",
  void, (FILE *file, int size, rtx x),
  NULL)
 
 /* Some target machines need to postscan each insn after it is output.  */
 DEFHOOK
 (final_postscan_insn,
- "",
+ "If defined, this target hook is a function which is executed just after the\n\
+output of assembler code for @var{insn}, to change the mode of the assembler\n\
+if necessary.\n\
+\n\
+Here the argument @var{opvec} is the vector containing the operands\n\
+extracted from @var{insn}, and @var{noperands} is the number of\n\
+elements of the vector which contain meaningful data for this insn.\n\
+The contents of this vector are what was used to convert the insn\n\
+template into assembler code, so you can change the assembler mode\n\
+by checking the contents of the vector.",
  void, (FILE *file, rtx insn, rtx *opvec, int noperands),
  NULL)
 
 /* Emit the trampoline template.  This hook may be NULL.  */
 DEFHOOK
 (trampoline_template,
- "",
+ "This hook is called by @code{assemble_trampoline_template} to output,\n\
+on the stream @var{f}, assembler code for a block of data that contains\n\
+the constant parts of a trampoline.  This code should not include a\n\
+label---the label is taken care of automatically.\n\
+\n\
+If you do not define this hook, it means no template is needed\n\
+for the target.  Do not define this hook on systems where the block move\n\
+code to copy the trampoline into place would be larger than the code\n\
+to generate it on the spot.",
  void, (FILE *f),
  NULL)
 
@@ -468,7 +841,15 @@ 
 
 DEFHOOK
 (output_addr_const_extra,
- "",
+ "A target hook to recognize @var{rtx} patterns that @code{output_addr_const}\n\
+can't deal with, and output assembly code to @var{file} corresponding to\n\
+the pattern @var{x}.  This may be used to allow machine-dependent\n\
+@code{UNSPEC}s to appear within constants.\n\
+\n\
+If target hook fails to recognize a pattern, it must return @code{false},\n\
+so that a standard error message is printed.  If it prints an error message\n\
+itself, by calling, for example, @code{output_operand_lossage}, it may just\n\
+return @code{true}.",
  bool, (FILE *file, rtx x),
  hook_bool_FILEptr_rtx_false)
 
@@ -531,13 +912,28 @@ 
    the dependence LINK.  The default is to make no adjustment.  */
 DEFHOOK
 (adjust_cost,
- "",
+ "This function corrects the value of @var{cost} based on the\n\
+relationship between @var{insn} and @var{dep_insn} through the\n\
+dependence @var{link}.  It should return the new value.  The default\n\
+is to make no adjustment to @var{cost}.  This can be used for example\n\
+to specify to the scheduler using the traditional pipeline description\n\
+that an output- or anti-dependence does not incur the same cost as a\n\
+data-dependence.  If the scheduler using the automaton based pipeline\n\
+description, the cost of anti-dependence is zero and the cost of\n\
+output-dependence is maximum of one and the difference of latency\n\
+times of the first and the second insns.  If these values are not\n\
+acceptable, you could use the hook to modify them too.  See also\n\
+@pxref{Processor pipeline description}.",
  int, (rtx insn, rtx link, rtx dep_insn, int cost), NULL)
 
 /* Adjust the priority of an insn as you see fit.  Returns the new priority.  */
 DEFHOOK
 (adjust_priority,
- "",
+ "This hook adjusts the integer scheduling priority @var{priority} of\n\
+@var{insn}.  It should return the new priority.  Increase the priority to\n\
+execute @var{insn} earlier, reduce the priority to execute @var{insn}\n\
+later.  Do not define this hook if you do not need to adjust the\n\
+scheduling priorities of insns.",
  int, (rtx insn, int priority), NULL)
 
 /* Function which returns the maximum number of insns that can be
@@ -545,50 +941,104 @@ 
    over an entire compilation.  The default is 1.  */
 DEFHOOK
 (issue_rate,
- "",
+ "This hook returns the maximum number of instructions that can ever\n\
+issue at the same time on the target machine.  The default is one.\n\
+Although the insn scheduler can define itself the possibility of issue\n\
+an insn on the same cycle, the value can serve as an additional\n\
+constraint to issue insns on the same simulated processor cycle (see\n\
+hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}).\n\
+This value must be constant over the entire compilation.  If you need\n\
+it to vary depending on what the instructions are, you must use\n\
+@samp{TARGET_SCHED_VARIABLE_ISSUE}.",
  int, (void), NULL)
 
 /* Calculate how much this insn affects how many more insns we
    can emit this cycle.  Default is they all cost the same.  */
 DEFHOOK
 (variable_issue,
- "",
+ "This hook is executed by the scheduler after it has scheduled an insn\n\
+from the ready list.  It should return the number of insns which can\n\
+still be issued in the current cycle.  The default is\n\
+@samp{@w{@var{more} - 1}} for insns other than @code{CLOBBER} and\n\
+@code{USE}, which normally are not counted against the issue rate.\n\
+You should define this hook if some insns take more machine resources\n\
+than others, so that fewer insns can follow them in the same cycle.\n\
+@var{file} is either a null pointer, or a stdio stream to write any\n\
+debug output to.  @var{verbose} is the verbose level provided by\n\
+@option{-fsched-verbose-@var{n}}.  @var{insn} is the instruction that\n\
+was scheduled.",
  int, (FILE *file, int verbose, rtx insn, int more), NULL)
 
 /* Initialize machine-dependent scheduling code.  */
 DEFHOOK
 (init,
- "",
+ "This hook is executed by the scheduler at the beginning of each block of\n\
+instructions that are to be scheduled.  @var{file} is either a null\n\
+pointer, or a stdio stream to write any debug output to.  @var{verbose}\n\
+is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
+@var{max_ready} is the maximum number of insns in the current scheduling\n\
+region that can be live at the same time.  This can be used to allocate\n\
+scratch space if it is needed, e.g.@: by @samp{TARGET_SCHED_REORDER}.",
  void, (FILE *file, int verbose, int max_ready), NULL)
 
 /* Finalize machine-dependent scheduling code.  */
 DEFHOOK
 (finish,
- "",
+ "This hook is executed by the scheduler at the end of each block of\n\
+instructions that are to be scheduled.  It can be used to perform\n\
+cleanup of any actions done by the other scheduling hooks.  @var{file}\n\
+is either a null pointer, or a stdio stream to write any debug output\n\
+to.  @var{verbose} is the verbose level provided by\n\
+@option{-fsched-verbose-@var{n}}.",
  void, (FILE *file, int verbose), NULL)
 
  /* Initialize machine-dependent function wide scheduling code.  */
 DEFHOOK
 (init_global,
- "",
+ "This hook is executed by the scheduler after function level initializations.\n\
+@var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
+@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
+@var{old_max_uid} is the maximum insn uid when scheduling begins.",
  void, (FILE *file, int verbose, int old_max_uid), NULL)
 
 /* Finalize machine-dependent function wide scheduling code.  */
 DEFHOOK
 (finish_global,
- "",
+ "This is the cleanup hook corresponding to @code{TARGET_SCHED_INIT_GLOBAL}.\n\
+@var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
+@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.",
  void, (FILE *file, int verbose), NULL)
 
 /* Reorder insns in a machine-dependent fashion, in two different
        places.  Default does nothing.  */
 DEFHOOK
 (reorder,
- "",
+ "This hook is executed by the scheduler after it has scheduled the ready\n\
+list, to allow the machine description to reorder it (for example to\n\
+combine two small instructions together on @samp{VLIW} machines).\n\
+@var{file} is either a null pointer, or a stdio stream to write any\n\
+debug output to.  @var{verbose} is the verbose level provided by\n\
+@option{-fsched-verbose-@var{n}}.  @var{ready} is a pointer to the ready\n\
+list of instructions that are ready to be scheduled.  @var{n_readyp} is\n\
+a pointer to the number of elements in the ready list.  The scheduler\n\
+reads the ready list in reverse order, starting with\n\
+@var{ready}[@var{*n_readyp} @minus{} 1] and going to @var{ready}[0].  @var{clock}\n\
+is the timer tick of the scheduler.  You may modify the ready list and\n\
+the number of ready insns.  The return value is the number of insns that\n\
+can issue this cycle; normally this is just @code{issue_rate}.  See also\n\
+@samp{TARGET_SCHED_REORDER2}.",
  int, (FILE *file, int verbose, rtx *ready, int *n_readyp, int clock), NULL)
 
 DEFHOOK
 (reorder2,
- "",
+ "Like @samp{TARGET_SCHED_REORDER}, but called at a different time.  That\n\
+function is called whenever the scheduler starts a new cycle.  This one\n\
+is called once per iteration over a cycle, immediately after\n\
+@samp{TARGET_SCHED_VARIABLE_ISSUE}; it can reorder the ready list and\n\
+return the number of insns to be scheduled in the same cycle.  Defining\n\
+this hook can be useful if there are frequent situations where\n\
+scheduling one insn causes other insns to become ready in the same\n\
+cycle.  These other insns can then be taken into account properly.",
  int, (FILE *file, int verbose, rtx *ready, int *n_readyp, int clock), NULL)
 
 /* The following member value is a pointer to a function called
@@ -596,7 +1046,13 @@ 
    by two parameter values (head and tail correspondingly).  */
 DEFHOOK
 (dependencies_evaluation_hook,
- "",
+ "This hook is called after evaluation forward dependencies of insns in\n\
+chain given by two parameter values (@var{head} and @var{tail}\n\
+correspondingly) but before insns scheduling of the insn chain.  For\n\
+example, it can be used for better insn classification if it requires\n\
+analysis of dependencies.  This hook can use backward and forward\n\
+dependencies of the insn scheduler because they are already\n\
+calculated.",
  void, (rtx head, rtx tail), NULL)
 
 /* The values of the following four members are pointers to functions
@@ -611,22 +1067,31 @@ 
 
 DEFHOOK
 (init_dfa_pre_cycle_insn,
- "",
+ "The hook can be used to initialize data used by the previous hook.",
  void, (void), NULL)
 
 DEFHOOK
 (dfa_pre_cycle_insn,
- "",
+ "The hook returns an RTL insn.  The automaton state used in the\n\
+pipeline hazard recognizer is changed as if the insn were scheduled\n\
+when the new simulated processor cycle starts.  Usage of the hook may\n\
+simplify the automaton pipeline description for some @acronym{VLIW}\n\
+processors.  If the hook is defined, it is used only for the automaton\n\
+based pipeline description.  The default is not to change the state\n\
+when the new simulated processor cycle starts.",
  rtx, (void), NULL)
 
 DEFHOOK
 (init_dfa_post_cycle_insn,
- "",
+ "The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but\n\
+used to initialize data used by the previous hook.",
  void, (void), NULL)
 
 DEFHOOK
 (dfa_post_cycle_insn,
- "",
+ "The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
+to changed the state as if the insn were scheduled when the new\n\
+simulated processor cycle finishes.",
  rtx, (void), NULL)
 
 /* The values of the following two members are pointers to
@@ -636,12 +1101,18 @@ 
 
 DEFHOOK
 (dfa_pre_advance_cycle,
- "",
+ "The hook to notify target that the current simulated cycle is about to finish.\n\
+The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
+to change the state in more complicated situations - e.g., when advancing\n\
+state on a single insn is not enough.",
  void, (void), NULL)
 
 DEFHOOK
 (dfa_post_advance_cycle,
- "",
+ "The hook to notify target that new simulated cycle has just started.\n\
+The hook is analogous to @samp{TARGET_SCHED_DFA_POST_CYCLE_INSN} but used\n\
+to change the state in more complicated situations - e.g., when advancing\n\
+state on a single insn is not enough.",
  void, (void), NULL)
 
 /* The following member value is a pointer to a function returning value
@@ -653,7 +1124,32 @@ 
    insns on the same cycle.  */
 DEFHOOK
 (first_cycle_multipass_dfa_lookahead,
- "",
+ "This hook controls better choosing an insn from the ready insn queue\n\
+for the @acronym{DFA}-based insn scheduler.  Usually the scheduler\n\
+chooses the first insn from the queue.  If the hook returns a positive\n\
+value, an additional scheduler code tries all permutations of\n\
+@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()}\n\
+subsequent ready insns to choose an insn whose issue will result in\n\
+maximal number of issued insns on the same cycle.  For the\n\
+@acronym{VLIW} processor, the code could actually solve the problem of\n\
+packing simple insns into the @acronym{VLIW} insn.  Of course, if the\n\
+rules of @acronym{VLIW} packing are described in the automaton.\n\
+\n\
+This code also could be used for superscalar @acronym{RISC}\n\
+processors.  Let us consider a superscalar @acronym{RISC} processor\n\
+with 3 pipelines.  Some insns can be executed in pipelines @var{A} or\n\
+@var{B}, some insns can be executed only in pipelines @var{B} or\n\
+@var{C}, and one insn can be executed in pipeline @var{B}.  The\n\
+processor may issue the 1st insn into @var{A} and the 2nd one into\n\
+@var{B}.  In this case, the 3rd insn will wait for freeing @var{B}\n\
+until the next cycle.  If the scheduler issues the 3rd insn the first,\n\
+the processor could issue all 3 insns per cycle.\n\
+\n\
+Actually this code demonstrates advantages of the automaton based\n\
+pipeline hazard recognizer.  We try quickly and easy many insn\n\
+schedules to choose the best one.\n\
+\n\
+The default is no multipass scheduling.",
  int, (void), NULL)
 
 /* The following member value is pointer to a function controlling
@@ -662,7 +1158,13 @@ 
    passed as the parameter, the insn will be not chosen to be issued.  */
 DEFHOOK
 (first_cycle_multipass_dfa_lookahead_guard,
- "",
+ "\n\
+This hook controls what insns from the ready insn queue will be\n\
+considered for the multipass insn scheduling.  If the hook returns\n\
+zero for @var{insn}, the insn will be not chosen to\n\
+be issued.\n\
+\n\
+The default is that any ready insns can be chosen to be issued.",
  int, (rtx insn), NULL)
 
 /* This hook prepares the target for a new round of multipass
@@ -676,7 +1178,8 @@ 
    scheduling on current cycle.  */
 DEFHOOK
 (first_cycle_multipass_begin,
- "",
+ "This hook prepares the target backend for a new round of multipass\n\
+scheduling.",
  void, (void *data, char *ready_try, int n_ready, bool first_cycle_insn_p),
  NULL)
 
@@ -692,7 +1195,7 @@ 
    to a state before issuing INSN.  */
 DEFHOOK
 (first_cycle_multipass_issue,
- "",
+ "This hook is called when multipass scheduling evaluates instruction INSN.",
  void, (void *data, char *ready_try, int n_ready, rtx insn,
 	const void *prev_data), NULL)
 
@@ -707,7 +1210,8 @@ 
    elements in READY_TRY to non-zero.  */
 DEFHOOK
 (first_cycle_multipass_backtrack,
- "",
+ "This is called when multipass scheduling backtracks from evaluation of\n\
+an instruction.",
  void, (const void *data, char *ready_try, int n_ready), NULL)
 
 /* This hook notifies the target about the result of the concluded current
@@ -720,7 +1224,8 @@ 
    usually after advancing the cycle count.  */
 DEFHOOK
 (first_cycle_multipass_end,
- "",
+ "This hook notifies the target about the result of the concluded current\n\
+round of multipass scheduling.",
  void, (const void *data), NULL)
 
 /* This hook is called to initialize target-specific data for multipass
@@ -730,7 +1235,7 @@ 
    described in DFA.  */
 DEFHOOK
 (first_cycle_multipass_init,
- "",
+ "This hook initializes target-specific data used in multipass scheduling.",
  void, (void *data), NULL)
 
 /* This hook is called to finalize target-specific data for multipass
@@ -740,7 +1245,7 @@ 
    described in DFA.  */
 DEFHOOK
 (first_cycle_multipass_fini,
- "",
+ "This hook finalizes target-specific data used in multipass scheduling.",
  void, (void *data), NULL)
 
 /* The following member value is pointer to a function called by
@@ -756,7 +1261,16 @@ 
    the previous insn has been issued and the current processor cycle.  */
 DEFHOOK
 (dfa_new_cycle,
- "",
+ "This hook is called by the insn scheduler before issuing @var{insn}\n\
+on cycle @var{clock}.  If the hook returns nonzero,\n\
+@var{insn} is not issued on this processor cycle.  Instead,\n\
+the processor cycle is advanced.  If *@var{sort_p}\n\
+is zero, the insn ready queue is not sorted on the new cycle\n\
+start as usually.  @var{dump} and @var{verbose} specify the file and\n\
+verbosity level to use for debugging output.\n\
+@var{last_clock} and @var{clock} are, respectively, the\n\
+processor cycle on which the previous insn has been issued,\n\
+and the current processor cycle.",
  int, (FILE *dump, int verbose, rtx insn, int last_clock,
        int clock, int *sort_p),
  NULL)
@@ -772,7 +1286,24 @@ 
    second insn (second parameter).  */
 DEFHOOK
 (is_costly_dependence,
- "",
+ "This hook is used to define which dependences are considered costly by\n\
+the target, so costly that it is not advisable to schedule the insns that\n\
+are involved in the dependence too close to one another.  The parameters\n\
+to this hook are as follows:  The first parameter @var{_dep} is the dependence\n\
+being evaluated.  The second parameter @var{cost} is the cost of the\n\
+dependence as estimated by the scheduler, and the third\n\
+parameter @var{distance} is the distance in cycles between the two insns.\n\
+The hook returns @code{true} if considering the distance between the two\n\
+insns the dependence between them is considered costly by the target,\n\
+and @code{false} otherwise.\n\
+\n\
+Defining this hook can be useful in multiple-issue out-of-order machines,\n\
+where (a) it's practically hopeless to predict the actual data/resource\n\
+delays, however: (b) there's a better chance to predict the actual grouping\n\
+that will be formed, and (c) correctly emulating the grouping can be very\n\
+important.  In such targets one may want to allow issuing dependent insns\n\
+closer to one another---i.e., closer than the dependence distance;  however,\n\
+not in cases of ``costly dependences'', which this hooks allows to define.",
  bool, (struct _dep *_dep, int cost, int distance), NULL)
 
 DEFHOOK_UNDOC
@@ -787,7 +1318,9 @@ 
    that new instructions were emitted.  */
 DEFHOOK
 (h_i_d_extended,
- "",
+ "This hook is called by the insn scheduler after emitting a new instruction to\n\
+the instruction stream.  The hook notifies a target backend to extend its\n\
+per instruction data structures.",
  void, (void), NULL)
 
 /* Next 5 functions are for multi-point scheduling.  */
@@ -795,31 +1328,33 @@ 
 /* Allocate memory for scheduler context.  */
 DEFHOOK
 (alloc_sched_context,
- "",
+ "Return a pointer to a store large enough to hold target scheduling context.",
  void *, (void), NULL)
 
 /* Fills the context from the local machine scheduler context.  */
 DEFHOOK
 (init_sched_context,
- "",
+ "Initialize store pointed to by @var{tc} to hold target scheduling context.\n\
+It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the\n\
+beginning of the block.  Otherwise, copy the current context into @var{tc}.",
  void, (void *tc, bool clean_p), NULL)
 
 /* Sets local machine scheduler context to a saved value.  */
 DEFHOOK
 (set_sched_context,
- "",
+ "Copy target scheduling context pointed to by @var{tc} to the current context.",
  void, (void *tc), NULL)
 
 /* Clears a scheduler context so it becomes like after init.  */
 DEFHOOK
 (clear_sched_context,
- "",
+ "Deallocate internal data in target scheduling context pointed to by @var{tc}.",
  void, (void *tc), NULL)
 
 /* Frees the scheduler context.  */
 DEFHOOK
 (free_sched_context,
- "",
+ "Deallocate a store for target scheduling context pointed to by @var{tc}.",
  void, (void *tc), NULL)
 
 /* The following member value is a pointer to a function called
@@ -834,7 +1369,14 @@ 
    generated one.  */
 DEFHOOK
 (speculate_insn,
- "",
+ "This hook is called by the insn scheduler when @var{insn} has only\n\
+speculative dependencies and therefore can be scheduled speculatively.\n\
+The hook is used to check if the pattern of @var{insn} has a speculative\n\
+version and, in case of successful check, to generate that speculative\n\
+pattern.  The hook should return 1, if the instruction has a speculative form,\n\
+or @minus{}1, if it doesn't.  @var{request} describes the type of requested\n\
+speculation.  If the return value equals 1 then @var{new_pat} is assigned\n\
+the generated speculative pattern.",
  int, (rtx insn, unsigned int dep_status, rtx *new_pat), NULL)
 
 /* The following member value is a pointer to a function called
@@ -842,7 +1384,9 @@ 
    passed as the parameter needs a recovery block.  */
 DEFHOOK
 (needs_block_p,
- "",
+ "This hook is called by the insn scheduler during generation of recovery code\n\
+for @var{insn}.  It should return @code{true}, if the corresponding check\n\
+instruction should branch to recovery code, or @code{false} otherwise.",
  bool, (unsigned int dep_status), NULL)
 
 /* The following member value is a pointer to a function called
@@ -854,7 +1398,14 @@ 
    is being performed.  */
 DEFHOOK
 (gen_spec_check,
- "",
+ "This hook is called by the insn scheduler to generate a pattern for recovery\n\
+check instruction.  If @var{mutate_p} is zero, then @var{insn} is a\n\
+speculative instruction for which the check should be generated.\n\
+@var{label} is either a label of a basic block, where recovery code should\n\
+be emitted, or a null pointer, when requested check doesn't branch to\n\
+recovery code (a simple check).  If @var{mutate_p} is nonzero, then\n\
+a pattern for a branchy check corresponding to a simple check denoted by\n\
+@var{insn} should be generated.  In this case @var{label} can't be null.",
  rtx, (rtx insn, rtx label, unsigned int ds), NULL)
 
 /* The following member value is a pointer to a function controlling
@@ -865,7 +1416,16 @@ 
    that stand at the first position of the ready list.  */
 DEFHOOK
 (first_cycle_multipass_dfa_lookahead_guard_spec,
- "",
+ "This hook is used as a workaround for\n\
+@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD} not being\n\
+called on the first instruction of the ready list.  The hook is used to\n\
+discard speculative instructions that stand first in the ready list from\n\
+being scheduled on the current cycle.  If the hook returns @code{false},\n\
+@var{insn} will not be chosen to be issued.\n\
+For non-speculative instructions,\n\
+the hook should always return @code{true}.  For example, in the ia64 backend\n\
+the hook is used to cancel data speculative insns when the ALAT table\n\
+is nearly full.",
  bool, (const_rtx insn), NULL)
 
 /* The following member value is a pointer to a function that provides
@@ -873,7 +1433,10 @@ 
    The parameter is a pointer to spec_info variable.  */
 DEFHOOK
 (set_sched_flags,
- "",
+ "This hook is used by the insn scheduler to find out what features should be\n\
+enabled/used.\n\
+The structure *@var{spec_info} should be filled in by the target.\n\
+The structure describes speculation types that can be used in the scheduler.",
  void, (struct spec_info_def *spec_info), NULL)
 
 DEFHOOK_UNDOC
@@ -898,7 +1461,12 @@ 
    to ddg variable.  */
 DEFHOOK
 (sms_res_mii,
- "",
+ "This hook is called by the swing modulo scheduler to calculate a\n\
+resource-based lower bound which is based on the resources available in\n\
+the machine and the resources required by each instruction.  The target\n\
+backend can use @var{g} to calculate such bound.  A very simple lower\n\
+bound will be used in case this hook is not implemented: the total number\n\
+of instructions divided by the issue rate.",
  int, (struct ddg *g), NULL)
 
 /* The following member value is a function that initializes dispatch
@@ -906,7 +1474,8 @@ 
    parameters.  */
 DEFHOOK
 (dispatch_do,
-"",
+"This hook is called by Haifa Scheduler.  It performs the operation specified\n\
+in its second parameter.",
 void, (rtx insn, int x),
 hook_void_rtx_int)
 
@@ -915,7 +1484,8 @@ 
    as the second parameter is true.  */
 DEFHOOK
 (dispatch,
-"",
+"This hook is called by Haifa Scheduler.  It returns true if dispatch scheduling\n\
+is supported in hardware and the condition specified in the parameter is true.",
 bool, (rtx insn, int x),
 hook_bool_rtx_int_false)
 
@@ -948,14 +1518,44 @@ 
    function.  */
 DEFHOOK
 (builtin_mask_for_load,
- "",
+ "This hook should return the DECL of a function @var{f} that given an\n\
+address @var{addr} as an argument returns a mask @var{m} that can be\n\
+used to extract from two vectors the relevant data that resides in\n\
+@var{addr} in case @var{addr} is not properly aligned.\n\
+\n\
+The autovectorizer, when vectorizing a load operation from an address\n\
+@var{addr} that may be unaligned, will generate two vector loads from\n\
+the two aligned addresses around @var{addr}. It then generates a\n\
+@code{REALIGN_LOAD} operation to extract the relevant data from the\n\
+two loaded vectors. The first two arguments to @code{REALIGN_LOAD},\n\
+@var{v1} and @var{v2}, are the two vectors, each of size @var{VS}, and\n\
+the third argument, @var{OFF}, defines how the data will be extracted\n\
+from these two vectors: if @var{OFF} is 0, then the returned vector is\n\
+@var{v2}; otherwise, the returned vector is composed from the last\n\
+@var{VS}-@var{OFF} elements of @var{v1} concatenated to the first\n\
+@var{OFF} elements of @var{v2}.\n\
+\n\
+If this hook is defined, the autovectorizer will generate a call\n\
+to @var{f} (using the DECL tree that this hook returns) and will\n\
+use the return value of @var{f} as the argument @var{OFF} to\n\
+@code{REALIGN_LOAD}. Therefore, the mask @var{m} returned by @var{f}\n\
+should comply with the semantics expected by @code{REALIGN_LOAD}\n\
+described above.\n\
+If this hook is not defined, then @var{addr} will be used as\n\
+the argument @var{OFF} to @code{REALIGN_LOAD}, in which case the low\n\
+log2(@var{VS}) @minus{} 1 bits of @var{addr} will be considered.",
  tree, (void), NULL)
 
 /* Returns a code for builtin that realizes vectorized version of
    function, or NULL_TREE if not available.  */
 DEFHOOK
 (builtin_vectorized_function,
- "",
+ "This hook should return the decl of a function that implements the\n\
+vectorized variant of the builtin function with builtin function code\n\
+@var{code} or @code{NULL_TREE} if such a function is not available.\n\
+The value of @var{fndecl} is the builtin function declaration.  The\n\
+return type of the vectorized function shall be of vector type\n\
+@var{vec_type_out} and the argument types should be @var{vec_type_in}.",
  tree, (tree fndecl, tree vec_type_out, tree vec_type_in),
  default_builtin_vectorized_function)
 
@@ -963,7 +1563,15 @@ 
    vector conversion, or NULL_TREE if not available.  */
 DEFHOOK
 (builtin_conversion,
- "",
+ "This hook should return the DECL of a function that implements conversion of the\n\
+input vector of type @var{src_type} to type @var{dest_type}.\n\
+The value of @var{code} is one of the enumerators in @code{enum tree_code} and\n\
+specifies how the conversion is to be applied\n\
+(truncation, rounding, etc.).\n\
+\n\
+If this hook is defined, the autovectorizer will use the\n\
+@code{TARGET_VECTORIZE_BUILTIN_CONVERSION} target hook when vectorizing\n\
+conversion. Otherwise, it will return @code{NULL_TREE}.",
  tree, (unsigned code, tree dest_type, tree src_type),
  default_builtin_vectorized_conversion)
 
@@ -972,7 +1580,9 @@ 
    on the data type and misalignment value.  */
 DEFHOOK
 (builtin_vectorization_cost,
- "",
+ "Returns cost of different scalar or vector statements for vectorization cost model.\n\
+For vector memory operations the cost may depend on type (@var{vectype}) and\n\
+misalignment value (@var{misalign}).",
  int, (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign),
  default_builtin_vectorization_cost)
 
@@ -980,7 +1590,7 @@ 
    iterations) for the given type.  */
 DEFHOOK
 (vector_alignment_reachable,
- "",
+ "Return true if vector alignment is reachable (by peeling N iterations) for the given type.",
  bool, (const_tree type, bool is_packed),
  default_builtin_vector_alignment_reachable)
 
@@ -988,7 +1598,7 @@ 
    A NULL indicates that all constants are valid permutations.  */
 DEFHOOK
 (vec_perm_const_ok,
- "",
+ "Return true if a vector created for @code{vec_perm_const} is valid.",
  bool, (enum machine_mode, const unsigned char *sel),
  NULL)
 
@@ -997,7 +1607,11 @@ 
    is true if the access is defined in a packed struct.  */
 DEFHOOK
 (support_vector_misalignment,
- "",
+ "This hook should return true if the target supports misaligned vector\n\
+store/load of a specific factor denoted in the @var{misalignment}\n\
+parameter.  The vector store/load should be of machine mode @var{mode} and\n\
+the elements in the vectors should be of type @var{type}.  @var{is_packed}\n\
+parameter is true if the memory access is defined in a packed struct.",
  bool,
  (enum machine_mode mode, const_tree type, int misalignment, bool is_packed),
  default_builtin_support_vector_misalignment)
@@ -1024,7 +1638,10 @@ 
    scalar mode.  */
 DEFHOOK
 (preferred_simd_mode,
- "",
+ "This hook should return the preferred mode for vectorizing scalar\n\
+mode @var{mode}.  The default is\n\
+equal to @code{word_mode}, because the vectorizer can do some\n\
+transformations even in absence of specialized @acronym{SIMD} hardware.",
  enum machine_mode,
  (enum machine_mode mode),
  default_preferred_simd_mode)
@@ -1033,7 +1650,10 @@ 
    after processing the preferred one derived from preferred_simd_mode.  */
 DEFHOOK
 (autovectorize_vector_sizes,
- "",
+ "This hook should return a mask of sizes that should be iterated over\n\
+after trying to autovectorize using the vector size derived from the\n\
+mode returned by @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE}.\n\
+The default is zero which means to not iterate over other vector sizes.",
  unsigned int,
  (void),
  default_autovectorize_vector_sizes)
@@ -1041,7 +1661,11 @@ 
 /* Target builtin that implements vector gather operation.  */
 DEFHOOK
 (builtin_gather,
- "",
+ "Target builtin that implements vector gather operation.  @var{mem_vectype}\n\
+is the vector type of the load and @var{index_type} is scalar type of\n\
+the index, scaled by @var{scale}.\n\
+The default is @code{NULL_TREE} which means to not vectorize gather\n\
+loads.",
  tree,
  (const_tree mem_vectype, const_tree index_type, int scale),
  NULL)
@@ -1110,7 +1734,13 @@ 
   end of the code affected by an attribute or pragma.  */
 DEFHOOK
 (override_options_after_change,
- "",
+ "This target function is similar to the hook @code{TARGET_OPTION_OVERRIDE}\n\
+but is called when the optimize level is changed via an attribute or\n\
+pragma or when it is reset at the end of the code affected by the\n\
+attribute or pragma.  It is not called at the beginning of compilation\n\
+when @code{TARGET_OPTION_OVERRIDE} is called so if you want to perform these\n\
+actions then, you should have @code{TARGET_OPTION_OVERRIDE} call\n\
+@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}.",
  void, (void),
  hook_void_void)
 
@@ -1123,35 +1753,65 @@ 
 /* Return machine mode for libgcc expanded cmp instructions.  */
 DEFHOOK
 (libgcc_cmp_return_mode,
- "",
+ "This target hook should return the mode to be used for the return value\n\
+of compare instructions expanded to libgcc calls.  If not defined\n\
+@code{word_mode} is returned which is the right choice for a majority of\n\
+targets.",
  enum machine_mode, (void),
  default_libgcc_cmp_return_mode)
 
 /* Return machine mode for libgcc expanded shift instructions.  */
 DEFHOOK
 (libgcc_shift_count_mode,
- "",
+ "This target hook should return the mode to be used for the shift count operand\n\
+of shift instructions expanded to libgcc calls.  If not defined\n\
+@code{word_mode} is returned which is the right choice for a majority of\n\
+targets.",
  enum machine_mode, (void),
  default_libgcc_shift_count_mode)
 
 /* Return machine mode to be used for _Unwind_Word type.  */
 DEFHOOK
 (unwind_word_mode,
- "",
+ "Return machine mode to be used for @code{_Unwind_Word} type.\n\
+The default is to use @code{word_mode}.",
  enum machine_mode, (void),
  default_unwind_word_mode)
 
 /* Given two decls, merge their attributes and return the result.  */
 DEFHOOK
 (merge_decl_attributes,
- "",
+ "Define this target hook if the merging of decl attributes needs special\n\
+handling.  If defined, the result is a list of the combined\n\
+@code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}.\n\
+@var{newdecl} is a duplicate declaration of @var{olddecl}.  Examples of\n\
+when this is needed are when one attribute overrides another, or when an\n\
+attribute is nullified by a subsequent definition.  This function may\n\
+call @code{merge_attributes} to handle machine-independent merging.\n\
+\n\
+@findex TARGET_DLLIMPORT_DECL_ATTRIBUTES\n\
+If the only target-specific handling you require is @samp{dllimport}\n\
+for Microsoft Windows targets, you should define the macro\n\
+@code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}.  The compiler\n\
+will then define a function called\n\
+@code{merge_dllimport_decl_attributes} which can then be defined as\n\
+the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}.  You can also\n\
+add @code{handle_dll_attribute} in the attribute table for your port\n\
+to perform initial processing of the @samp{dllimport} and\n\
+@samp{dllexport} attributes.  This is done in @file{i386/cygwin.h} and\n\
+@file{i386/i386.c}, for example.",
  tree, (tree olddecl, tree newdecl),
  merge_decl_attributes)
 
 /* Given two types, merge their attributes and return the result.  */
 DEFHOOK
 (merge_type_attributes,
- "",
+ "Define this target hook if the merging of type attributes needs special\n\
+handling.  If defined, the result is a list of the combined\n\
+@code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}.  It is assumed\n\
+that @code{comptypes} has already been called and returned 1.  This\n\
+function may call @code{merge_attributes} to handle machine-independent\n\
+merging.",
  tree, (tree type1, tree type2),
  merge_type_attributes)
 
@@ -1159,14 +1819,22 @@ 
    Ignored if NULL.  */
 DEFHOOKPOD
 (attribute_table,
- "",
+ "If defined, this target hook points to an array of @samp{struct\n\
+attribute_spec} (defined in @file{tree.h}) specifying the machine\n\
+specific attributes for this target and some of the restrictions on the\n\
+entities to which these attributes are applied and the arguments they\n\
+take.",
  const struct attribute_spec *, NULL)
 
 /* Return true iff attribute NAME expects a plain identifier as its first
    argument.  */
 DEFHOOK
 (attribute_takes_identifier_p,
- "",
+ "If defined, this target hook is a function which returns true if the\n\
+machine-specific attribute named @var{name} expects an identifier\n\
+given as its first argument to be passed on as a plain identifier, not\n\
+subjected to name lookup.  If this is not defined, the default is\n\
+false for all machine-specific attributes.",
  bool, (const_tree name),
  hook_bool_const_tree_false)
 
@@ -1175,21 +1843,35 @@ 
    (which causes a warning to be generated).  */
 DEFHOOK
 (comp_type_attributes,
- "",
+ "If defined, this target hook is a function which returns zero if the attributes on\n\
+@var{type1} and @var{type2} are incompatible, one if they are compatible,\n\
+and two if they are nearly compatible (which causes a warning to be\n\
+generated).  If this is not defined, machine-specific attributes are\n\
+supposed always to be compatible.",
  int, (const_tree type1, const_tree type2),
  hook_int_const_tree_const_tree_1)
 
 /* Assign default attributes to the newly defined TYPE.  */
 DEFHOOK
 (set_default_type_attributes,
- "",
+ "If defined, this target hook is a function which assigns default attributes to\n\
+the newly defined @var{type}.",
  void, (tree type),
  hook_void_tree)
 
 /* Insert attributes on the newly created DECL.  */
 DEFHOOK
 (insert_attributes,
- "",
+ "Define this target hook if you want to be able to add attributes to a decl\n\
+when it is being created.  This is normally useful for back ends which\n\
+wish to implement a pragma by using the attributes which correspond to\n\
+the pragma's effect.  The @var{node} argument is the decl which is being\n\
+created.  The @var{attr_ptr} argument is a pointer to the attribute list\n\
+for this decl.  The list itself should not be modified, since it may be\n\
+shared with other decls, but attributes may be chained on the head of\n\
+the list and @code{*@var{attr_ptr}} modified to point to the new\n\
+attributes, or a copy of the list may be made if further changes are\n\
+needed.",
  void, (tree node, tree *attr_ptr),
  hook_void_tree_treeptr)
 
@@ -1197,7 +1879,11 @@ 
    can be inlined despite its machine attributes, false otherwise.  */
 DEFHOOK
 (function_attribute_inlinable_p,
- "",
+ "@cindex inlining\n\
+This target hook returns @code{true} if it is ok to inline @var{fndecl}\n\
+into the current function, despite its having target-specific\n\
+attributes, @code{false} otherwise.  By default, if a function has a\n\
+target specific attribute attached to it, it will not be inlined.",
  bool, (const_tree fndecl),
  hook_bool_const_tree_false)
 
@@ -1205,7 +1891,31 @@ 
    Microsoft Visual C++ bitfield layout rules.  */
 DEFHOOK
 (ms_bitfield_layout_p,
- "",
+ "This target hook returns @code{true} if bit-fields in the given\n\
+@var{record_type} are to be laid out following the rules of Microsoft\n\
+Visual C/C++, namely: (i) a bit-field won't share the same storage\n\
+unit with the previous bit-field if their underlying types have\n\
+different sizes, and the bit-field will be aligned to the highest\n\
+alignment of the underlying types of itself and of the previous\n\
+bit-field; (ii) a zero-sized bit-field will affect the alignment of\n\
+the whole enclosing structure, even if it is unnamed; except that\n\
+(iii) a zero-sized bit-field will be disregarded unless it follows\n\
+another bit-field of nonzero size.  If this hook returns @code{true},\n\
+other macros that control bit-field layout are ignored.\n\
+\n\
+When a bit-field is inserted into a packed record, the whole size\n\
+of the underlying type is used by one or more same-size adjacent\n\
+bit-fields (that is, if its long:3, 32 bits is used in the record,\n\
+and any additional adjacent long bit-fields are packed into the same\n\
+chunk of 32 bits.  However, if the size changes, a new field of that\n\
+size is allocated).  In an unpacked record, this is the same as using\n\
+alignment, but not equivalent when packing.\n\
+\n\
+If both MS bit-fields and @samp{__attribute__((packed))} are used,\n\
+the latter will take precedence.  If @samp{__attribute__((packed))} is\n\
+used on a single field when MS bit-fields are in use, it will take\n\
+precedence for that field, but the alignment of the rest of the structure\n\
+may affect its placement.",
  bool, (const_tree record_type),
  hook_bool_const_tree_false)
 
@@ -1228,21 +1938,24 @@ 
 /* True if the target supports decimal floating point.  */
 DEFHOOK
 (decimal_float_supported_p,
- "",
+ "Returns true if the target supports decimal floating point.",
  bool, (void),
  default_decimal_float_supported_p)
 
 /* True if the target supports fixed-point.  */
 DEFHOOK
 (fixed_point_supported_p,
- "",
+ "Returns true if the target supports fixed-point arithmetic.",
  bool, (void),
  default_fixed_point_supported_p)
 
 /* Return true if anonymous bitfields affect structure alignment.  */
 DEFHOOK
 (align_anon_bitfield,
- "",
+ "When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine\n\
+whether unnamed bitfields affect the alignment of the containing\n\
+structure.  The hook should return true if the structure should inherit\n\
+the alignment requirements of an unnamed bitfield's type.",
  bool, (void),
  hook_bool_void_false)
 
@@ -1250,14 +1963,32 @@ 
    Return false if they should use the container type.  */
 DEFHOOK
 (narrow_volatile_bitfield,
- "",
+ "This target hook should return @code{true} if accesses to volatile bitfields\n\
+should use the narrowest mode possible.  It should return @code{false} if\n\
+these accesses should use the bitfield container type.\n\
+\n\
+The default is @code{!TARGET_STRICT_ALIGN}.",
  bool, (void),
  hook_bool_void_false)
 
 /* Set up target-specific built-in functions.  */
 DEFHOOK
 (init_builtins,
- "",
+ "Define this hook if you have any machine-specific built-in functions\n\
+that need to be defined.  It should be a function that performs the\n\
+necessary setup.\n\
+\n\
+Machine specific built-in functions can be useful to expand special machine\n\
+instructions that would otherwise not normally be generated because\n\
+they have no equivalent in the source language (for example, SIMD vector\n\
+instructions or prefetch instructions).\n\
+\n\
+To create a built-in function, call the function\n\
+@code{lang_hooks.builtin_function}\n\
+which is defined by the language front end.  You can use any type nodes set\n\
+up by @code{build_common_tree_nodes};\n\
+only language front ends that use those two functions will call\n\
+@samp{TARGET_INIT_BUILTINS}.",
  void, (void),
  hook_void_void)
 
@@ -1267,13 +1998,27 @@ 
    is outside of the range of valid target builtin function codes.  */
 DEFHOOK
 (builtin_decl,
- "",
+ "Define this hook if you have any machine-specific built-in functions\n\
+that need to be defined.  It should be a function that returns the\n\
+builtin function declaration for the builtin function code @var{code}.\n\
+If there is no such builtin and it cannot be initialized at this time\n\
+if @var{initialize_p} is true the function should return @code{NULL_TREE}.\n\
+If @var{code} is out of range the function should return\n\
+@code{error_mark_node}.",
  tree, (unsigned code, bool initialize_p), NULL)
 
 /* Expand a target-specific builtin.  */
 DEFHOOK
 (expand_builtin,
- "",
+ "\n\
+Expand a call to a machine specific built-in function that was set up by\n\
+@samp{TARGET_INIT_BUILTINS}.  @var{exp} is the expression for the\n\
+function call; the result should go to @var{target} if that is\n\
+convenient, and have mode @var{mode} if that is convenient.\n\
+@var{subtarget} may be used as the target for computing one of\n\
+@var{exp}'s operands.  @var{ignore} is nonzero if the value is to be\n\
+ignored.  This function should return the result of the call to the\n\
+built-in function.",
  rtx,
  (tree exp, rtx target, rtx subtarget, enum machine_mode mode, int ignore),
  default_expand_builtin)
@@ -1285,14 +2030,28 @@ 
    has type VEC(tree,gc)*, but we don't want to include tree.h here.  */
 DEFHOOK
 (resolve_overloaded_builtin,
- "",
+ "Select a replacement for a machine specific built-in function that\n\
+was set up by @samp{TARGET_INIT_BUILTINS}.  This is done\n\
+@emph{before} regular type checking, and so allows the target to\n\
+implement a crude form of function overloading.  @var{fndecl} is the\n\
+declaration of the built-in function.  @var{arglist} is the list of\n\
+arguments passed to the built-in function.  The result is a\n\
+complete expression that implements the operation, usually\n\
+another @code{CALL_EXPR}.\n\
+@var{arglist} really has type @samp{VEC(tree,gc)*}",
  tree, (unsigned int /*location_t*/ loc, tree fndecl, void *arglist), NULL)
 
 /* Fold a target-specific builtin to a tree valid for both GIMPLE
    and GENERIC.  */
 DEFHOOK
 (fold_builtin,
- "",
+ "Fold a call to a machine specific built-in function that was set up by\n\
+@samp{TARGET_INIT_BUILTINS}.  @var{fndecl} is the declaration of the\n\
+built-in function.  @var{n_args} is the number of arguments passed to\n\
+the function; the arguments themselves are pointed to by @var{argp}.\n\
+The result is another tree, valid for both GIMPLE and GENERIC,\n\
+containing a simplified expression for the call's result.  If\n\
+@var{ignore} is true the value will be ignored.",
  tree, (tree fndecl, int n_args, tree *argp, bool ignore),
  hook_tree_tree_int_treep_bool_null)
 
@@ -1316,7 +2075,12 @@ 
    and 0 if they are the same. */
 DEFHOOK
 (compare_version_priority,
- "",
+ "This hook is used to compare the target attributes in two functions to\n\
+determine which function's features get higher priority.  This is used\n\
+during function multi-versioning to figure out the order in which two\n\
+versions must be dispatched.  A function version with a higher priority\n\
+is checked for dispatching earlier.  @var{decl1} and @var{decl2} are\n\
+ the two function decls that will be compared.",
  int, (tree decl1, tree decl2), NULL)
 
 /*  Target hook is used to generate the dispatcher logic to invoke the right
@@ -1325,7 +2089,10 @@ 
     must be generated.  */
 DEFHOOK
 (generate_version_dispatcher_body,
- "",
+ "This hook is used to generate the dispatcher logic to invoke the right\n\
+function version at run-time for a given set of function versions.\n\
+@var{arg} points to the callgraph node of the dispatcher function whose\n\
+body must be generated.",
  tree, (void *arg), NULL) 
 
 /* Target hook is used to get the dispatcher function for a set of function
@@ -1334,14 +2101,23 @@ 
    identical versions.  */
 DEFHOOK
 (get_function_versions_dispatcher,
- "",
+ "This hook is used to get the dispatcher function for a set of function\n\
+versions.  The dispatcher function is called to invoke the right function\n\
+version at run-time. @var{decl} is one version from a set of semantically\n\
+identical versions.",
  tree, (void *decl), NULL)
 
 /* Returns a code for a target-specific builtin that implements
    reciprocal of the function, or NULL_TREE if not available.  */
 DEFHOOK
 (builtin_reciprocal,
- "",
+ "This hook should return the DECL of a function that implements reciprocal of\n\
+the builtin function with builtin function code @var{fn}, or\n\
+@code{NULL_TREE} if such a function is not available.  @var{md_fn} is true\n\
+when @var{fn} is a code of a machine-dependent builtin function.  When\n\
+@var{sqrt} is true, additional optimizations that apply only to the reciprocal\n\
+of a square root function are performed, and only reciprocals of @code{sqrt}\n\
+function are valid.",
  tree, (unsigned fn, bool md_fn, bool sqrt),
  default_builtin_reciprocal)
 
@@ -1350,14 +2126,50 @@ 
    NULL.  */
 DEFHOOK
 (mangle_type,
- "",
+ "If your target defines any fundamental types, or any types your target\n\
+uses should be mangled differently from the default, define this hook\n\
+to return the appropriate encoding for these types as part of a C++\n\
+mangled name.  The @var{type} argument is the tree structure representing\n\
+the type to be mangled.  The hook may be applied to trees which are\n\
+not target-specific fundamental types; it should return @code{NULL}\n\
+for all such types, as well as arguments it does not recognize.  If the\n\
+return value is not @code{NULL}, it must point to a statically-allocated\n\
+string constant.\n\
+\n\
+Target-specific fundamental types might be new fundamental types or\n\
+qualified versions of ordinary fundamental types.  Encode new\n\
+fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name}\n\
+is the name used for the type in source code, and @var{n} is the\n\
+length of @var{name} in decimal.  Encode qualified versions of\n\
+ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where\n\
+@var{name} is the name used for the type qualifier in source code,\n\
+@var{n} is the length of @var{name} as above, and @var{code} is the\n\
+code used to represent the unqualified version of this type.  (See\n\
+@code{write_builtin_type} in @file{cp/mangle.c} for the list of\n\
+codes.)  In both cases the spaces are for clarity; do not include any\n\
+spaces in your string.\n\
+\n\
+This hook is applied to types prior to typedef resolution.  If the mangled\n\
+name for a particular type depends only on that type's main variant, you\n\
+can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT}\n\
+before mangling.\n\
+\n\
+The default version of this hook always returns @code{NULL}, which is\n\
+appropriate for a target that does not define any new fundamental\n\
+types.",
  const char *, (const_tree type),
  hook_constcharptr_const_tree_null)
 
 /* Make any adjustments to libfunc names needed for this target.  */
 DEFHOOK
 (init_libfuncs,
- "",
+ "This hook should declare additional library routines or rename\n\
+existing ones, using the functions @code{set_optab_libfunc} and\n\
+@code{init_one_libfunc} defined in @file{optabs.c}.\n\
+@code{init_optabs} calls this macro after initializing all the normal\n\
+library routines.\n\
+\n\
+The default is to do nothing.  Most ports don't need to define this hook.",
  void, (void),
  hook_void_void)
 
@@ -1377,7 +2189,15 @@ 
 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 DEFHOOK
 (section_type_flags,
- "",
+ "Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION}\n\
+based on a variable or function decl, a section name, and whether or not the\n\
+declaration's initializer may contain runtime relocations.  @var{decl} may be\n\
+null, in which case read-write data should be assumed.\n\
+\n\
+The default version of this function handles choosing code vs data,\n\
+read-only vs read-write data, and @code{flag_pic}.  You should only\n\
+need to override this if your target has special flags that might be\n\
+set via @code{__attribute__}.",
  unsigned int, (tree decl, const char *name, int reloc),
  default_section_type_flags)
 
@@ -1385,7 +2205,18 @@ 
    not, at the current point in the compilation.  */
 DEFHOOK
 (cannot_modify_jumps_p,
- "",
+ "This target hook returns @code{true} past the point in which new jump\n\
+instructions could be created.  On machines that require a register for\n\
+every jump such as the SHmedia ISA of SH5, this point would typically be\n\
+reload, so this target hook should be defined to a function such as:\n\
+\n\
+@smallexample\n\
+static bool\n\
+cannot_modify_jumps_past_reload_p ()\n\
+@{\n\
+  return (reload_completed || reload_in_progress);\n\
+@}\n\
+@end smallexample",
  bool, (void),
  hook_bool_void_false)
 
@@ -1404,7 +2235,11 @@ 
    optimizations should be applied.  */
 DEFHOOK
 (branch_target_register_class,
- "",
+ "This target hook returns a register class for which branch target register\n\
+optimizations should be applied.  All registers in this class should be\n\
+usable interchangeably.  After reload, registers in this class will be\n\
+re-allocated and loads will be hoisted out of loops and be subjected\n\
+to inter-block scheduling.",
  reg_class_t, (void),
  default_branch_target_register_class)
 
@@ -1414,35 +2249,66 @@ 
    already been generated.  */
 DEFHOOK
 (branch_target_register_callee_saved,
- "",
+ "Branch target register optimization will by default exclude callee-saved\n\
+registers\n\
+that are not already live during the current function; if this target hook\n\
+returns true, they will be included.  The target code must than make sure\n\
+that all target registers in the class returned by\n\
+@samp{TARGET_BRANCH_TARGET_REGISTER_CLASS} that might need saving are\n\
+saved.  @var{after_prologue_epilogue_gen} indicates if prologues and\n\
+epilogues have already been generated.  Note, even if you only return\n\
+true when @var{after_prologue_epilogue_gen} is false, you still are likely\n\
+to have to make special provisions in @code{INITIAL_ELIMINATION_OFFSET}\n\
+to reserve space for caller-saved target registers.",
  bool, (bool after_prologue_epilogue_gen),
  hook_bool_bool_false)
 
 /* Return true if the target supports conditional execution.  */
 DEFHOOK
 (have_conditional_execution,
- "",
+ "This target hook returns true if the target supports conditional execution.\n\
+This target hook is required only when the target has several different\n\
+modes and they have different conditional execution capability, such as ARM.",
  bool, (void),
  default_have_conditional_execution)
 
 /* Return a new value for loop unroll size.  */
 DEFHOOK
 (loop_unroll_adjust,
- "",
+ "This target hook returns a new value for the number of times @var{loop}\n\
+should be unrolled. The parameter @var{nunroll} is the number of times\n\
+the loop is to be unrolled. The parameter @var{loop} is a pointer to\n\
+the loop, which is going to be checked for unrolling. This target hook\n\
+is required only when the target has special constraints like maximum\n\
+number of memory accesses.",
  unsigned, (unsigned nunroll, struct loop *loop),
  NULL)
 
 /* True if X is a legitimate MODE-mode immediate operand.  */
 DEFHOOK
 (legitimate_constant_p,
- "",
+ "This hook returns true if @var{x} is a legitimate constant for a\n\
+@var{mode}-mode immediate operand on the target machine.  You can assume that\n\
+@var{x} satisfies @code{CONSTANT_P}, so you need not check this.\n\
+\n\
+The default definition returns true.",
  bool, (enum machine_mode mode, rtx x),
  hook_bool_mode_rtx_true)
 
 /* True if the constant X cannot be placed in the constant pool.  */
 DEFHOOK
 (cannot_force_const_mem,
- "",
+ "This hook should return true if @var{x} is of a form that cannot (or\n\
+should not) be spilled to the constant pool.  @var{mode} is the mode\n\
+of @var{x}.\n\
+\n\
+The default version of this hook returns false.\n\
+\n\
+The primary reason to define this hook is to prevent reload from\n\
+deciding that a non-legitimate constant would be better reloaded\n\
+from the constant pool instead of spilling and reloading a register\n\
+holding the constant.  This restriction is often true of addresses\n\
+of TLS symbols for various targets.",
  bool, (enum machine_mode mode, rtx x),
  hook_bool_mode_rtx_false)
 
@@ -1454,7 +2320,10 @@ 
 /* True if X is considered to be commutative.  */
 DEFHOOK
 (commutative_p,
- "",
+ "This target hook returns @code{true} if @var{x} is considered to be commutative.\n\
+Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider\n\
+PLUS to be commutative inside a MEM@.  @var{outer_code} is the rtx code\n\
+of the enclosing rtl, if known, otherwise it is UNKNOWN.",
  bool, (const_rtx x, int outer_code),
  hook_bool_const_rtx_commutative_p)
 
@@ -1462,7 +2331,20 @@ 
    on the mode of the memory reference it is used in.  */
 DEFHOOK
 (mode_dependent_address_p,
- "",
+ "This hook returns @code{true} if memory address @var{addr} in address\n\
+space @var{addrspace} can have\n\
+different meanings depending on the machine mode of the memory\n\
+reference it is used for or if the address is valid for some modes\n\
+but not others.\n\
+\n\
+Autoincrement and autodecrement addresses typically have mode-dependent\n\
+effects because the amount of the increment or decrement is the size\n\
+of the operand being addressed.  Some machines have other mode-dependent\n\
+addresses.  Many RISC machines have no mode-dependent addresses.\n\
+\n\
+You may assume that @var{addr} is a valid address for the machine.\n\
+\n\
+The default version of this hook returns @code{false}.",
  bool, (const_rtx addr, addr_space_t addrspace),
  default_mode_dependent_address_p)
 
@@ -1470,14 +2352,39 @@ 
    ways to make it legitimate.  Return X or an invalid address on failure.  */
 DEFHOOK
 (legitimize_address,
- "",
+ "This hook is given an invalid memory address @var{x} for an\n\
+operand of mode @var{mode} and should try to return a valid memory\n\
+address.\n\
+\n\
+@findex break_out_memory_refs\n\
+@var{x} will always be the result of a call to @code{break_out_memory_refs},\n\
+and @var{oldx} will be the operand that was given to that function to produce\n\
+@var{x}.\n\
+\n\
+The code of the hook should not alter the substructure of\n\
+@var{x}.  If it transforms @var{x} into a more legitimate form, it\n\
+should return the new @var{x}.\n\
+\n\
+It is not necessary for this hook to come up with a legitimate address,\n\
+with the exception of native TLS addresses (@pxref{Emulated TLS}).\n\
+The compiler has standard ways of doing so in all cases.  In fact, if\n\
+the target supports only emulated TLS, it\n\
+is safe to omit this hook or make it return @var{x} if it cannot find\n\
+a valid way to legitimize the address.  But often a machine-dependent\n\
+strategy can generate better code.",
  rtx, (rtx x, rtx oldx, enum machine_mode mode),
  default_legitimize_address)
 
 /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 DEFHOOK
 (delegitimize_address,
- "",
+ "This hook is used to undo the possibly obfuscating effects of the\n\
+@code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target\n\
+macros.  Some backend implementations of these macros wrap symbol\n\
+references inside an @code{UNSPEC} rtx to represent PIC or similar\n\
+addressing modes.  This target hook allows GCC's optimizers to understand\n\
+the semantics of these opaque @code{UNSPEC}s by converting them back\n\
+into their original form.",
  rtx, (rtx x),
  delegitimize_mem_from_attrs)
 
@@ -1485,46 +2392,126 @@ 
    section.  */
 DEFHOOK
 (const_not_ok_for_debug_p,
- "",
+ "This hook should return true if @var{x} should not be emitted into\n\
+debug sections.",
  bool, (rtx x),
  hook_bool_rtx_false)
 
 /* Given an address RTX, say whether it is valid.  */
 DEFHOOK
 (legitimate_address_p,
- "",
+ "A function that returns whether @var{x} (an RTX) is a legitimate memory\n\
+address on the target machine for a memory operand of mode @var{mode}.\n\
+\n\
+Legitimate addresses are defined in two variants: a strict variant and a\n\
+non-strict one.  The @var{strict} parameter chooses which variant is\n\
+desired by the caller.\n\
+\n\
+The strict variant is used in the reload pass.  It must be defined so\n\
+that any pseudo-register that has not been allocated a hard register is\n\
+considered a memory reference.  This is because in contexts where some\n\
+kind of register is required, a pseudo-register with no hard register\n\
+must be rejected.  For non-hard registers, the strict variant should look\n\
+up the @code{reg_renumber} array; it should then proceed using the hard\n\
+register number in the array, or treat the pseudo as a memory reference\n\
+if the array holds @code{-1}.\n\
+\n\
+The non-strict variant is used in other passes.  It must be defined to\n\
+accept all pseudo-registers in every context where some kind of\n\
+register is required.\n\
+\n\
+Normally, constant addresses which are the sum of a @code{symbol_ref}\n\
+and an integer are stored inside a @code{const} RTX to mark them as\n\
+constant.  Therefore, there is no need to recognize such sums\n\
+specifically as legitimate addresses.  Normally you would simply\n\
+recognize any @code{const} as legitimate.\n\
+\n\
+Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant\n\
+sums that are not marked with  @code{const}.  It assumes that a naked\n\
+@code{plus} indicates indexing.  If so, then you @emph{must} reject such\n\
+naked constant sums as illegitimate addresses, so that none of them will\n\
+be given to @code{PRINT_OPERAND_ADDRESS}.\n\
+\n\
+@cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation\n\
+On some machines, whether a symbolic address is legitimate depends on\n\
+the section that the address refers to.  On these machines, define the\n\
+target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information\n\
+into the @code{symbol_ref}, and then check for it here.  When you see a\n\
+@code{const}, you will have to look inside it to find the\n\
+@code{symbol_ref} in order to determine the section.  @xref{Assembler\n\
+Format}.\n\
+\n\
+@cindex @code{GO_IF_LEGITIMATE_ADDRESS}\n\
+Some ports are still using a deprecated legacy substitute for\n\
+this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro.  This macro\n\
+has this syntax:\n\
+\n\
+@example\n\
+#define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label})\n\
+@end example\n\
+\n\
+@noindent\n\
+and should @code{goto @var{label}} if the address @var{x} is a valid\n\
+address on the target machine for a memory operand of mode @var{mode}.\n\
+\n\
+@findex REG_OK_STRICT\n\
+Compiler source files that want to use the strict variant of this\n\
+macro define the macro @code{REG_OK_STRICT}.  You should use an\n\
+@code{#ifdef REG_OK_STRICT} conditional to define the strict variant in\n\
+that case and the non-strict variant otherwise.\n\
+\n\
+Using the hook is usually simpler because it limits the number of\n\
+files that are recompiled when changes are made.",
  bool, (enum machine_mode mode, rtx x, bool strict),
  default_legitimate_address_p)
 
 /* True if the given constant can be put into an object_block.  */
 DEFHOOK
 (use_blocks_for_constant_p,
- "",
+ "This hook should return true if pool entries for constant @var{x} can\n\
+be placed in an @code{object_block} structure.  @var{mode} is the mode\n\
+of @var{x}.\n\
+\n\
+The default version returns false for all constants.",
  bool, (enum machine_mode mode, const_rtx x),
  hook_bool_mode_const_rtx_false)
 
 /* True if the given decl can be put into an object_block.  */
 DEFHOOK
 (use_blocks_for_decl_p,
- "",
+ "This hook should return true if pool entries for @var{decl} should\n\
+be placed in an @code{object_block} structure.\n\
+\n\
+The default version returns true for all decls.",
  bool, (const_tree decl),
  hook_bool_const_tree_true)
 
 /* The minimum and maximum byte offsets for anchored addresses.  */
 DEFHOOKPOD
 (min_anchor_offset,
- "",
+ "The minimum offset that should be applied to a section anchor.\n\
+On most targets, it should be the smallest offset that can be\n\
+applied to a base register while still giving a legitimate address\n\
+for every mode.  The default value is 0.",
  HOST_WIDE_INT, 0)
 
 DEFHOOKPOD
 (max_anchor_offset,
- "",
+ "Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive)\n\
+offset that should be applied to section anchors.  The default\n\
+value is 0.",
  HOST_WIDE_INT, 0)
 
 /* True if section anchors can be used to access the given symbol.  */
 DEFHOOK
 (use_anchors_for_symbol_p,
- "",
+ "Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF}\n\
+@var{x}.  You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and\n\
+@samp{!SYMBOL_REF_ANCHOR_P (@var{x})}.\n\
+\n\
+The default version is correct for most targets, but you might need to\n\
+intercept this hook to handle things like target-specific attributes\n\
+or target-specific sections.",
  bool, (const_rtx x),
  default_use_anchors_for_symbol_p)
 
@@ -1542,7 +2529,16 @@ 
    this is an indirect call.  */
 DEFHOOK
 (function_ok_for_sibcall,
- "",
+ "True if it is ok to do sibling call optimization for the specified\n\
+call expression @var{exp}.  @var{decl} will be the called function,\n\
+or @code{NULL} if this is an indirect call.\n\
+\n\
+It is not uncommon for limitations of calling conventions to prevent\n\
+tail calls to functions outside the current unit of translation, or\n\
+during PIC compilation.  The hook is used to enforce these restrictions,\n\
+as the @code{sibcall} md pattern can not fail, or fall over to a\n\
+``normal'' call.  The criteria for successful sibling call optimization\n\
+may vary greatly between different architectures.",
  bool, (tree decl, tree exp),
  hook_bool_tree_tree_false)
 
@@ -1551,13 +2547,29 @@ 
    level, outside of any function scope.  */
 DEFHOOK
 (set_current_function,
- "",
+ "The compiler invokes this hook whenever it changes its current function\n\
+context (@code{cfun}).  You can define this function if\n\
+the back end needs to perform any initialization or reset actions on a\n\
+per-function basis.  For example, it may be used to implement function\n\
+attributes that affect register usage or code generation patterns.\n\
+The argument @var{decl} is the declaration for the new function context,\n\
+and may be null to indicate that the compiler has left a function context\n\
+and is returning to processing at the top level.\n\
+The default hook function does nothing.\n\
+\n\
+GCC sets @code{cfun} to a dummy function context during initialization of\n\
+some parts of the back end.  The hook function is not invoked in this\n\
+situation; you need not worry about the hook being invoked recursively,\n\
+or when the back end is in a partially-initialized state.\n\
+@code{cfun} might be @code{NULL} to indicate processing at top level,\n\
+outside of any function scope.",
  void, (tree decl), hook_void_tree)
 
 /* True if EXP should be placed in a "small data" section.  */
 DEFHOOK
 (in_small_data_p,
- "",
+ "Returns true if @var{exp} should be placed into a ``small data'' section.\n\
+The default version of this hook always returns false.",
  bool, (const_tree exp),
  hook_bool_const_tree_false)
 
@@ -1565,7 +2577,13 @@ 
    to the current executable or shared library.  */
 DEFHOOK
 (binds_local_p,
- "",
+ "Returns true if @var{exp} names an object for which name resolution\n\
+rules must resolve to the current ``module'' (dynamic shared library\n\
+or executable image).\n\
+\n\
+The default version of this hook implements the name resolution rules\n\
+for ELF, which has a looser model of global name binding than other\n\
+currently supported object file formats.",
  bool, (const_tree exp),
  default_binds_local_p)
 
@@ -1584,7 +2602,13 @@ 
    The default is to return ID without modification. */
 DEFHOOK
 (mangle_decl_assembler_name,
- "",
+ "Define this hook if you need to postprocess the assembler name generated\n\
+by target-independent code.  The @var{id} provided to this hook will be\n\
+the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C,\n\
+or the mangled name of the @var{decl} in C++).  The return value of the\n\
+hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on\n\
+your target system.  The default implementation of this hook just\n\
+returns the @var{id} provided.",
  tree, (tree decl, tree  id),
  default_mangle_decl_assembler_name)
 
@@ -1592,14 +2616,50 @@ 
    the associated SYMBOL_REF.  */
 DEFHOOK
 (encode_section_info,
- "",
+ "Define this hook if references to a symbol or a constant must be\n\
+treated differently depending on something about the variable or\n\
+function named by the symbol (such as what section it is in).\n\
+\n\
+The hook is executed immediately after rtl has been created for\n\
+@var{decl}, which may be a variable or function declaration or\n\
+an entry in the constant pool.  In either case, @var{rtl} is the\n\
+rtl in question.  Do @emph{not} use @code{DECL_RTL (@var{decl})}\n\
+in this hook; that field may not have been initialized yet.\n\
+\n\
+In the case of a constant, it is safe to assume that the rtl is\n\
+a @code{mem} whose address is a @code{symbol_ref}.  Most decls\n\
+will also have this form, but that is not guaranteed.  Global\n\
+register variables, for instance, will have a @code{reg} for their\n\
+rtl.  (Normally the right thing to do with such unusual rtl is\n\
+leave it alone.)\n\
+\n\
+The @var{new_decl_p} argument will be true if this is the first time\n\
+that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl.  It will\n\
+be false for subsequent invocations, which will happen for duplicate\n\
+declarations.  Whether or not anything must be done for the duplicate\n\
+declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}.\n\
+@var{new_decl_p} is always true when the hook is called for a constant.\n\
+\n\
+@cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO}\n\
+The usual thing for this hook to do is to record flags in the\n\
+@code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}.\n\
+Historically, the name string was modified if it was necessary to\n\
+encode more than one bit of information, but this practice is now\n\
+discouraged; use @code{SYMBOL_REF_FLAGS}.\n\
+\n\
+The default definition of this hook, @code{default_encode_section_info}\n\
+in @file{varasm.c}, sets a number of commonly-useful bits in\n\
+@code{SYMBOL_REF_FLAGS}.  Check whether the default does what you need\n\
+before overriding it.",
  void, (tree decl, rtx rtl, int new_decl_p),
  default_encode_section_info)
 
 /* Undo the effects of encode_section_info on the symbol string.  */
 DEFHOOK
 (strip_name_encoding,
- "",
+ "Decode @var{name} and return the real name part, sans\n\
+the characters that @code{TARGET_ENCODE_SECTION_INFO}\n\
+may have added.",
  const char *, (const char *name),
  default_strip_name_encoding)
 
@@ -1607,7 +2667,27 @@ 
    return the mask that they apply.  Return 0 otherwise.  */
 DEFHOOK
 (shift_truncation_mask,
- "",
+ "This function describes how the standard shift patterns for @var{mode}\n\
+deal with shifts by negative amounts or by more than the width of the mode.\n\
+@xref{shift patterns}.\n\
+\n\
+On many machines, the shift patterns will apply a mask @var{m} to the\n\
+shift count, meaning that a fixed-width shift of @var{x} by @var{y} is\n\
+equivalent to an arbitrary-width shift of @var{x} by @var{y & m}.  If\n\
+this is true for mode @var{mode}, the function should return @var{m},\n\
+otherwise it should return 0.  A return value of 0 indicates that no\n\
+particular behavior is guaranteed.\n\
+\n\
+Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does\n\
+@emph{not} apply to general shift rtxes; it applies only to instructions\n\
+that are generated by the named shift patterns.\n\
+\n\
+The default implementation of this function returns\n\
+@code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED}\n\
+and 0 otherwise.  This definition is always safe, but if\n\
+@code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns\n\
+nevertheless truncate the shift count, you may get better code\n\
+by overriding it.",
  unsigned HOST_WIDE_INT, (enum machine_mode mode),
  default_shift_truncation_mask)
 
@@ -1616,7 +2696,12 @@ 
    the reciprocal.  */
 DEFHOOK
 (min_divisions_for_recip_mul,
- "",
+ "When @option{-ffast-math} is in effect, GCC tries to optimize\n\
+divisions by the same divisor, by turning them into multiplications by\n\
+the reciprocal.  This target hook specifies the minimum number of divisions\n\
+that should be there for GCC to perform the optimization for a variable\n\
+of mode @var{mode}.  The default implementation returns 3 if the machine\n\
+has an instruction for the division, and 2 if it does not.",
  unsigned int, (enum machine_mode mode),
  default_min_divisions_for_recip_mul)
 
@@ -1627,14 +2712,40 @@ 
    necessarily defined at this point.  */
 DEFHOOK
 (mode_rep_extended,
- "",
+ "The representation of an integral mode can be such that the values\n\
+are always extended to a wider integral mode.  Return\n\
+@code{SIGN_EXTEND} if values of @var{mode} are represented in\n\
+sign-extended form to @var{rep_mode}.  Return @code{UNKNOWN}\n\
+otherwise.  (Currently, none of the targets use zero-extended\n\
+representation this way so unlike @code{LOAD_EXTEND_OP},\n\
+@code{TARGET_MODE_REP_EXTENDED} is expected to return either\n\
+@code{SIGN_EXTEND} or @code{UNKNOWN}.  Also no target extends\n\
+@var{mode} to @var{rep_mode} so that @var{rep_mode} is not the next\n\
+widest integral mode and currently we take advantage of this fact.)\n\
+\n\
+Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN}\n\
+value even if the extension is not performed on certain hard registers\n\
+as long as for the @code{REGNO_REG_CLASS} of these hard registers\n\
+@code{CANNOT_CHANGE_MODE_CLASS} returns nonzero.\n\
+\n\
+Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP}\n\
+describe two related properties.  If you define\n\
+@code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want\n\
+to define @code{LOAD_EXTEND_OP (mode)} to return the same type of\n\
+extension.\n\
+\n\
+In order to enforce the representation of @code{mode},\n\
+@code{TRULY_NOOP_TRUNCATION} should return false when truncating to\n\
+@code{mode}.",
  int, (enum machine_mode mode, enum machine_mode rep_mode),
  default_mode_rep_extended)
 
 /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 DEFHOOK
 (valid_pointer_mode,
- "",
+ "Define this to return nonzero if the port can handle pointers\n\
+with machine mode @var{mode}.  The default version of this\n\
+hook returns true for both @code{ptr_mode} and @code{Pmode}.",
  bool, (enum machine_mode mode),
  default_valid_pointer_mode)
 
@@ -1657,14 +2768,20 @@ 
 /* MODE to use for a pointer into another address space.  */
 DEFHOOK
 (pointer_mode,
- "",
+ "Define this to return the machine mode to use for pointers to\n\
+@var{address_space} if the target supports named address spaces.\n\
+The default version of this hook returns @code{ptr_mode} for the\n\
+generic address space only.",
  enum machine_mode, (addr_space_t address_space),
  default_addr_space_pointer_mode)
 
 /* MODE to use for an address in another address space.  */
 DEFHOOK
 (address_mode,
- "",
+ "Define this to return the machine mode to use for addresses in\n\
+@var{address_space} if the target supports named address spaces.\n\
+The default version of this hook returns @code{Pmode} for the\n\
+generic address space only.",
  enum machine_mode, (addr_space_t address_space),
  default_addr_space_address_mode)
 
@@ -1672,7 +2789,13 @@ 
    in another address space.  */
 DEFHOOK
 (valid_pointer_mode,
- "",
+ "Define this to return nonzero if the port can handle pointers\n\
+with machine mode @var{mode} to address space @var{as}.  This target\n\
+hook is the same as the @code{TARGET_VALID_POINTER_MODE} target hook,\n\
+except that it includes explicit named address space support.  The default\n\
+version of this hook returns true for the modes returned by either the\n\
+@code{TARGET_ADDR_SPACE_POINTER_MODE} or @code{TARGET_ADDR_SPACE_ADDRESS_MODE}\n\
+target hooks for the given address space.",
  bool, (enum machine_mode mode, addr_space_t as),
  default_addr_space_valid_pointer_mode)
 
@@ -1680,7 +2803,12 @@ 
    space for a given mode.  */
 DEFHOOK
 (legitimate_address_p,
- "",
+ "Define this to return true if @var{exp} is a valid address for mode\n\
+@var{mode} in the named address space @var{as}.  The @var{strict}\n\
+parameter says whether strict addressing is in effect after reload has\n\
+finished.  This target hook is the same as the\n\
+@code{TARGET_LEGITIMATE_ADDRESS_P} target hook, except that it includes\n\
+explicit named address space support.",
  bool, (enum machine_mode mode, rtx exp, bool strict, addr_space_t as),
  default_addr_space_legitimate_address_p)
 
@@ -1689,21 +2817,34 @@ 
    independent methods to make the address valid.  */
 DEFHOOK
 (legitimize_address,
- "",
+ "Define this to modify an invalid address @var{x} to be a valid address\n\
+with mode @var{mode} in the named address space @var{as}.  This target\n\
+hook is the same as the @code{TARGET_LEGITIMIZE_ADDRESS} target hook,\n\
+except that it includes explicit named address space support.",
  rtx, (rtx x, rtx oldx, enum machine_mode mode, addr_space_t as),
  default_addr_space_legitimize_address)
 
 /* True if one named address space is a subset of another named address. */
 DEFHOOK
 (subset_p,
- "",
+ "Define this to return whether the @var{subset} named address space is\n\
+contained within the @var{superset} named address space.  Pointers to\n\
+a named address space that is a subset of another named address space\n\
+will be converted automatically without a cast if used together in\n\
+arithmetic operations.  Pointers to a superset address space can be\n\
+converted to pointers to a subset address space via explicit casts.",
  bool, (addr_space_t subset, addr_space_t superset),
  default_addr_space_subset_p)
 
 /* Function to convert an rtl expression from one address space to another.  */
 DEFHOOK
 (convert,
- "",
+ "Define this to convert the pointer expression represented by the RTL\n\
+@var{op} with type @var{from_type} that points to a named address\n\
+space to a new pointer expression with type @var{to_type} that points\n\
+to a different named address space.  When this hook it called, it is\n\
+guaranteed that one of the two address spaces is a subset of the other,\n\
+as determined by the @code{TARGET_ADDR_SPACE_SUBSET_P} target hook.",
  rtx, (rtx op, tree from_type, tree to_type),
  default_addr_space_convert)
 
@@ -1717,7 +2858,15 @@ 
    the arithmetic is supported.  */
 DEFHOOK
 (scalar_mode_supported_p,
- "",
+ "Define this to return nonzero if the port is prepared to handle\n\
+insns involving scalar mode @var{mode}.  For a scalar mode to be\n\
+considered supported, all the basic arithmetic and comparisons\n\
+must work.\n\
+\n\
+The default version of this hook returns true for any mode\n\
+required to handle the basic C types (as defined by the port).\n\
+Included here are the double-word arithmetic supported by the\n\
+code in @file{optabs.c}.",
  bool, (enum machine_mode mode),
  default_scalar_mode_supported_p)
 
@@ -1726,7 +2875,9 @@ 
    for further details.  */
 DEFHOOK
 (vector_mode_supported_p,
- "",
+ "Define this to return nonzero if the port is prepared to handle\n\
+insns involving vector mode @var{mode}.  At the very least, it\n\
+must have move patterns for this mode.",
  bool, (enum machine_mode mode),
  hook_bool_mode_false)
 
@@ -1776,7 +2927,24 @@ 
    TO, using MODE.  */
 DEFHOOK
 (register_move_cost,
- "",
+ "This target hook should return the cost of moving data of mode @var{mode}\n\
+from a register in class @var{from} to one in class @var{to}.  The classes\n\
+are expressed using the enumeration values such as @code{GENERAL_REGS}.\n\
+A value of 2 is the default; other values are interpreted relative to\n\
+that.\n\
+\n\
+It is not required that the cost always equal 2 when @var{from} is the\n\
+same as @var{to}; on some machines it is expensive to move between\n\
+registers if they are not general registers.\n\
+\n\
+If reload sees an insn consisting of a single @code{set} between two\n\
+hard registers, and if @code{TARGET_REGISTER_MOVE_COST} applied to their\n\
+classes returns a value of 2, reload does not check to ensure that the\n\
+constraints of the insn are met.  Setting a cost of other than 2 will\n\
+allow reload to verify that the constraints are met.  You should do this\n\
+if the @samp{mov@var{m}} pattern's constraints do not allow such copying.\n\
+\n\
+The default version of this function returns 2.",
  int, (enum machine_mode mode, reg_class_t from, reg_class_t to),
  default_register_move_cost)
 
@@ -1785,7 +2953,27 @@ 
    license grant.  Also, the documentation uses a different name for RCLASS.  */
 DEFHOOK
 (memory_move_cost,
- "",
+ "This target hook should return the cost of moving data of mode @var{mode}\n\
+between a register of class @var{rclass} and memory; @var{in} is @code{false}\n\
+if the value is to be written to memory, @code{true} if it is to be read in.\n\
+This cost is relative to those in @code{TARGET_REGISTER_MOVE_COST}.\n\
+If moving between registers and memory is more expensive than between two\n\
+registers, you should add this target hook to express the relative cost.\n\
+\n\
+If you do not add this target hook, GCC uses a default cost of 4 plus\n\
+the cost of copying via a secondary reload register, if one is\n\
+needed.  If your machine requires a secondary reload register to copy\n\
+between memory and a register of @var{rclass} but the reload mechanism is\n\
+more complex than copying via an intermediate, use this target hook to\n\
+reflect the actual cost of the move.\n\
+\n\
+GCC defines the function @code{memory_move_secondary_cost} if\n\
+secondary reloads are needed.  It computes the costs due to copying via\n\
+a secondary register.  If your machine copies from memory using a\n\
+secondary register in the conventional way but the default base value of\n\
+4 is not correct for your machine, use this target hook to add some other\n\
+value to the result of that function.  The arguments to that function\n\
+are the same as to this target hook.",
  int, (enum machine_mode mode, reg_class_t rclass, bool in),
  default_memory_move_cost)
 
@@ -1795,7 +2983,35 @@ 
    but it should prevent extending the lifetime of these registers.  */
 DEFHOOK
 (small_register_classes_for_mode_p,
- "",
+ "Define this to return nonzero for machine modes for which the port has\n\
+small register classes.  If this target hook returns nonzero for a given\n\
+@var{mode}, the compiler will try to minimize the lifetime of registers\n\
+in @var{mode}.  The hook may be called with @code{VOIDmode} as argument.\n\
+In this case, the hook is expected to return nonzero if it returns nonzero\n\
+for any mode.\n\
+\n\
+On some machines, it is risky to let hard registers live across arbitrary\n\
+insns.  Typically, these machines have instructions that require values\n\
+to be in specific registers (like an accumulator), and reload will fail\n\
+if the required hard register is used for another purpose across such an\n\
+insn.\n\
+\n\
+Passes before reload do not know which hard registers will be used\n\
+in an instruction, but the machine modes of the registers set or used in\n\
+the instruction are already known.  And for some machines, register\n\
+classes are small for, say, integer registers but not for floating point\n\
+registers.  For example, the AMD x86-64 architecture requires specific\n\
+registers for the legacy x86 integer instructions, but there are many\n\
+SSE registers for floating point operations.  On such targets, a good\n\
+strategy may be to return nonzero from this hook for @code{INTEGRAL_MODE_P}\n\
+machine modes but zero for the SSE register classes.\n\
+\n\
+The default version of this hook returns false for any mode.  It is always\n\
+safe to redefine this hook to return with a nonzero value.  But if you\n\
+unnecessarily define it, you will reduce the amount of optimizations\n\
+that can be performed in some cases.  If you do not define this hook\n\
+to return a nonzero value when it is required, the compiler will run out\n\
+of spill registers and print a fatal error message.",
  bool, (enum machine_mode mode),
  hook_bool_mode_false)
 
@@ -1815,7 +3031,35 @@ 
    not necessarily defined at this point.  */
 DEFHOOK
 (rtx_costs,
- "",
+ "This target hook describes the relative costs of RTL expressions.\n\
+\n\
+The cost may depend on the precise form of the expression, which is\n\
+available for examination in @var{x}, and the fact that @var{x} appears\n\
+as operand @var{opno} of an expression with rtx code @var{outer_code}.\n\
+That is, the hook can assume that there is some rtx @var{y} such\n\
+that @samp{GET_CODE (@var{y}) == @var{outer_code}} and such that\n\
+either (a) @samp{XEXP (@var{y}, @var{opno}) == @var{x}} or\n\
+(b) @samp{XVEC (@var{y}, @var{opno})} contains @var{x}.\n\
+\n\
+@var{code} is @var{x}'s expression code---redundant, since it can be\n\
+obtained with @code{GET_CODE (@var{x})}.\n\
+\n\
+In implementing this hook, you can use the construct\n\
+@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
+instructions.\n\
+\n\
+On entry to the hook, @code{*@var{total}} contains a default estimate\n\
+for the cost of the expression.  The hook should modify this value as\n\
+necessary.  Traditionally, the default costs are @code{COSTS_N_INSNS (5)}\n\
+for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus\n\
+operations, and @code{COSTS_N_INSNS (1)} for all other operations.\n\
+\n\
+When optimizing for code size, i.e.@: when @code{speed} is\n\
+false, this target hook should be used to estimate the relative\n\
+size cost of an expression, again relative to @code{COSTS_N_INSNS}.\n\
+\n\
+The hook returns true when all subexpressions of @var{x} have been\n\
+processed, and false when @code{rtx_cost} should recurse.",
  bool, (rtx x, int code, int outer_code, int opno, int *total, bool speed),
  hook_bool_rtx_int_int_int_intp_bool_false)
 
@@ -1823,21 +3067,75 @@ 
    invalid addresses.  */
 DEFHOOK
 (address_cost,
- "",
+ "This hook computes the cost of an addressing mode that contains\n\
+@var{address}.  If not defined, the cost is computed from\n\
+the @var{address} expression and the @code{TARGET_RTX_COST} hook.\n\
+\n\
+For most CISC machines, the default cost is a good approximation of the\n\
+true cost of the addressing mode.  However, on RISC machines, all\n\
+instructions normally have the same length and execution time.  Hence\n\
+all addresses will have equal costs.\n\
+\n\
+In cases where more than one form of an address is known, the form with\n\
+the lowest cost will be used.  If multiple forms have the same, lowest,\n\
+cost, the one that is the most complex will be used.\n\
+\n\
+For example, suppose an address that is equal to the sum of a register\n\
+and a constant is used twice in the same basic block.  When this macro\n\
+is not defined, the address will be computed in a register and memory\n\
+references will be indirect through that register.  On machines where\n\
+the cost of the addressing mode containing the sum is no higher than\n\
+that of a simple indirect reference, this will produce an additional\n\
+instruction and possibly require an additional register.  Proper\n\
+specification of this macro eliminates this overhead for such machines.\n\
+\n\
+This hook is never called with an invalid address.\n\
+\n\
+On machines where an address involving more than one register is as\n\
+cheap as an address computation involving only one register, defining\n\
+@code{TARGET_ADDRESS_COST} to reflect this can cause two registers to\n\
+be live over a region of code where only one would have been if\n\
+@code{TARGET_ADDRESS_COST} were not defined in that manner.  This effect\n\
+should be considered in the definition of this macro.  Equivalent costs\n\
+should probably only be given to addresses with different numbers of\n\
+registers on machines with lots of registers.",
  int, (rtx address, enum machine_mode mode, addr_space_t as, bool speed),
  default_address_cost)
 
 /* Return where to allocate pseudo for a given hard register initial value.  */
 DEFHOOK
 (allocate_initial_value,
- "",
+ "\n\
+When the initial value of a hard register has been copied in a pseudo\n\
+register, it is often not necessary to actually allocate another register\n\
+to this pseudo register, because the original hard register or a stack slot\n\
+it has been saved into can be used.  @code{TARGET_ALLOCATE_INITIAL_VALUE}\n\
+is called at the start of register allocation once for each hard register\n\
+that had its initial value copied by using\n\
+@code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}.\n\
+Possible values are @code{NULL_RTX}, if you don't want\n\
+to do any special allocation, a @code{REG} rtx---that would typically be\n\
+the hard register itself, if it is known not to be clobbered---or a\n\
+@code{MEM}.\n\
+If you are returning a @code{MEM}, this is only a hint for the allocator;\n\
+it might decide to use another register anyways.\n\
+You may use @code{current_function_is_leaf} or \n\
+@code{REG_N_SETS} in the hook to determine if the hard\n\
+register in question will not be clobbered.\n\
+The default value of this hook is @code{NULL}, which disables any special\n\
+allocation.",
  rtx, (rtx hard_reg), NULL)
 
 /* Return nonzero if evaluating UNSPEC X might cause a trap.
    FLAGS has the same meaning as in rtlanal.c: may_trap_p_1.  */
 DEFHOOK
 (unspec_may_trap_p,
- "",
+ "This target hook returns nonzero if @var{x}, an @code{unspec} or\n\
+@code{unspec_volatile} operation, might cause a trap.  Targets can use\n\
+this hook to enhance precision of analysis for @code{unspec} and\n\
+@code{unspec_volatile} operations.  You may call @code{may_trap_p_1}\n\
+to analyze inner elements of @var{x} in which case @var{flags} should be\n\
+passed along.",
  int, (const_rtx x, unsigned flags),
  default_unspec_may_trap_p)
 
@@ -1849,7 +3147,12 @@ 
    hook should return NULL_RTX.  */
 DEFHOOK
 (dwarf_register_span,
- "",
+ "Given a register, this hook should return a parallel of registers to\n\
+represent where to find the register pieces.  Define this hook if the\n\
+register and its mode are represented in Dwarf in non-contiguous\n\
+locations, or if the register should be represented in more than one\n\
+register in Dwarf.  Otherwise, this hook should return @code{NULL_RTX}.\n\
+If not defined, the default is to return @code{NULL_RTX}.",
  rtx, (rtx reg),
  hook_rtx_rtx_null)
 
@@ -1859,7 +3162,12 @@ 
    code, given the address of the table.  */
 DEFHOOK
 (init_dwarf_reg_sizes_extra,
- "",
+ "If some registers are represented in Dwarf-2 unwind information in\n\
+multiple pieces, define this hook to fill in information about the\n\
+sizes of those pieces in the table used by the unwinder at runtime.\n\
+It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after\n\
+filling in a single size corresponding to each hard register;\n\
+@var{address} is the address of the table.",
  void, (tree address),
  hook_void_tree)
 
@@ -1872,7 +3180,18 @@ 
    at by the second argument should be set to -1.  */
 DEFHOOK
 (fixed_condition_code_regs,
- "",
+ "On targets which do not use @code{(cc0)}, and which use a hard\n\
+register rather than a pseudo-register to hold condition codes, the\n\
+regular CSE passes are often not able to identify cases in which the\n\
+hard register is set to a common value.  Use this hook to enable a\n\
+small pass which optimizes such cases.  This hook should return true\n\
+to enable this pass, and it should set the integers to which its\n\
+arguments point to the hard register numbers used for condition codes.\n\
+When there is only one such register, as is true on most systems, the\n\
+integer pointed to by @var{p2} should be set to\n\
+@code{INVALID_REGNUM}.\n\
+\n\
+The default version of this hook returns false.",
  bool, (unsigned int *p1, unsigned int *p2),
  hook_bool_uintp_uintp_false)
 
@@ -1883,7 +3202,16 @@ 
      VOIDmode.  */
 DEFHOOK
 (cc_modes_compatible,
- "",
+ "On targets which use multiple condition code modes in class\n\
+@code{MODE_CC}, it is sometimes the case that a comparison can be\n\
+validly done in more than one mode.  On such a system, define this\n\
+target hook to take two mode arguments and to return a mode in which\n\
+both comparisons may be validly done.  If there is no such mode,\n\
+return @code{VOIDmode}.\n\
+\n\
+The default version of this hook checks whether the modes are the\n\
+same.  If they are, it returns that mode.  If they are different, it\n\
+returns @code{VOIDmode}.",
  enum machine_mode, (enum machine_mode m1, enum machine_mode m2),
  default_cc_modes_compatible)
 
@@ -1891,34 +3219,59 @@ 
      delayed-branch scheduling.  */
 DEFHOOK
 (machine_dependent_reorg,
- "",
+ "If non-null, this hook performs a target-specific pass over the\n\
+instruction stream.  The compiler will run it at all optimization levels,\n\
+just before the point at which it normally does delayed-branch scheduling.\n\
+\n\
+The exact purpose of the hook varies from target to target.  Some use\n\
+it to do transformations that are necessary for correctness, such as\n\
+laying out in-function constant pools or avoiding hardware hazards.\n\
+Others use it as an opportunity to do some machine-dependent optimizations.\n\
+\n\
+You need not implement the hook if it has nothing to do.  The default\n\
+definition is null.",
  void, (void), NULL)
 
 /* Create the __builtin_va_list type.  */
 DEFHOOK
 (build_builtin_va_list,
- "",
+ "This hook returns a type node for @code{va_list} for the target.\n\
+The default version of the hook returns @code{void*}.",
  tree, (void),
  std_build_builtin_va_list)
 
 /* Enumerate the va list variants.  */
 DEFHOOK
 (enum_va_list_p,
- "",
+ "This target hook is used in function @code{c_common_nodes_and_builtins}\n\
+to iterate through the target specific builtin types for va_list. The\n\
+variable @var{idx} is used as iterator. @var{pname} has to be a pointer\n\
+to a @code{const char *} and @var{ptree} a pointer to a @code{tree} typed\n\
+variable.\n\
+The arguments @var{pname} and @var{ptree} are used to store the result of\n\
+this macro and are set to the name of the va_list builtin type and its\n\
+internal type.\n\
+If the return value of this macro is zero, then there is no more element.\n\
+Otherwise the @var{IDX} should be increased for the next call of this\n\
+macro to iterate through all types.",
  int, (int idx, const char **pname, tree *ptree),
  NULL)
 
 /* Get the cfun/fndecl calling abi __builtin_va_list type.  */
 DEFHOOK
 (fn_abi_va_list,
- "",
+ "This hook returns the va_list type of the calling convention specified by\n\
+@var{fndecl}.\n\
+The default version of this hook returns @code{va_list_type_node}.",
  tree, (tree fndecl),
  std_fn_abi_va_list)
 
 /* Get the __builtin_va_list type dependent on input type.  */
 DEFHOOK
 (canonical_va_list_type,
- "",
+ "This hook returns the va_list type of the calling convention specified by the\n\
+type of @var{type}. If @var{type} is not a valid va_list type, it returns\n\
+@code{NULL_TREE}.",
  tree, (tree type),
  std_canonical_va_list_type)
 
@@ -1931,7 +3284,10 @@ 
 /* Gimplifies a VA_ARG_EXPR.  */
 DEFHOOK
 (gimplify_va_arg_expr,
- "",
+ "This hook performs target-specific gimplification of\n\
+@code{VA_ARG_EXPR}.  The first two parameters correspond to the\n\
+arguments to @code{va_arg}; the latter two are as in\n\
+@code{gimplify.c:gimplify_expr}.",
  tree, (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p),
  std_gimplify_va_arg_expr)
 
@@ -1942,13 +3298,26 @@ 
    or an error message if not.  */
 DEFHOOK
 (get_pch_validity,
- "",
+ "This hook returns a pointer to the data needed by\n\
+@code{TARGET_PCH_VALID_P} and sets\n\
+@samp{*@var{sz}} to the size of the data in bytes.",
  void *, (size_t *sz),
  default_get_pch_validity)
 
 DEFHOOK
 (pch_valid_p,
- "",
+ "This hook checks whether the options used to create a PCH file are\n\
+compatible with the current settings.  It returns @code{NULL}\n\
+if so and a suitable error message if not.  Error messages will\n\
+be presented to the user and must be localized using @samp{_(@var{msg})}.\n\
+\n\
+@var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY}\n\
+when the PCH file was created and @var{sz} is the size of that data in bytes.\n\
+It's safe to assume that the data was created by the same version of the\n\
+compiler, so no format checking is needed.\n\
+\n\
+The default definition of @code{default_pch_valid_p} should be\n\
+suitable for most targets.",
  const char *, (const void *data, size_t sz),
  default_pch_valid_p)
 
@@ -1966,7 +3335,11 @@ 
    otherwise it returns an error message.  */
 DEFHOOK
 (check_pch_target_flags,
- "",
+ "If this hook is nonnull, the default implementation of\n\
+@code{TARGET_PCH_VALID_P} will use it to check for compatible values\n\
+of @code{target_flags}.  @var{pch_flags} specifies the value that\n\
+@code{target_flags} had when the PCH file was created.  The return\n\
+value is the same as for @code{TARGET_PCH_VALID_P}.",
  const char *, (int pch_flags), NULL)
 
 /* True if the compiler should give an enum type only as many
@@ -1974,7 +3347,12 @@ 
    that type.  */
 DEFHOOK
 (default_short_enums,
- "",
+ "This target hook should return true if the compiler should give an\n\
+@code{enum} type only as many bytes as it takes to represent the range\n\
+of possible values of that type.  It should return false if all\n\
+@code{enum} types should be allocated like @code{int}.\n\
+\n\
+The default is to return false.",
  bool, (void),
  hook_bool_void_false)
 
@@ -1982,7 +3360,11 @@ 
    of the current frame into the built-in setjmp buffer.  */
 DEFHOOK
 (builtin_setjmp_frame_value,
- "",
+ "This target hook should return an rtx that is used to store\n\
+the address of the current frame into the built in @code{setjmp} buffer.\n\
+The default value, @code{virtual_stack_vars_rtx}, is correct for most\n\
+machines.  One reason you may need to define this target hook is if\n\
+@code{hard_frame_pointer_rtx} is the appropriate value on your machine.",
  rtx, (void),
  default_builtin_setjmp_frame_value)
 
@@ -1990,7 +3372,14 @@ 
    the port wishes to automatically clobber for an asm.  */
 DEFHOOK
 (md_asm_clobbers,
- "",
+ "This target hook should add to @var{clobbers} @code{STRING_CST} trees for\n\
+any hard regs the port wishes to automatically clobber for an asm.\n\
+It should return the result of the last @code{tree_cons} used to add a\n\
+clobber.  The @var{outputs}, @var{inputs} and @var{clobber} lists are the\n\
+corresponding parameters to the asm and may be inspected to avoid\n\
+clobbering a register that is an input or output of the asm.  You can use\n\
+@code{tree_overlaps_hard_reg_set}, declared in @file{tree.h}, to test\n\
+for overlap with regards to asm-declared registers.",
  tree, (tree outputs, tree inputs, tree clobbers),
  hook_tree_tree_tree_tree_3rd_identity)
 
@@ -2001,7 +3390,9 @@ 
    the function is being declared as an int.  */
 DEFHOOK
 (dwarf_calling_convention,
- "",
+ "Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to\n\
+be emitted for each function.  Instead of an integer return the enum\n\
+value for the @code{DW_CC_} tag.",
  int, (const_tree function),
  hook_int_const_tree_0)
 
@@ -2014,7 +3405,19 @@ 
    to let the backend emit the call frame instructions.  */
 DEFHOOK
 (dwarf_handle_frame_unspec,
- "",
+ "This target hook allows the backend to emit frame-related insns that\n\
+contain UNSPECs or UNSPEC_VOLATILEs.  The DWARF 2 call frame debugging\n\
+info engine will invoke it on insns of the form\n\
+@smallexample\n\
+(set (reg) (unspec [@dots{}] UNSPEC_INDEX))\n\
+@end smallexample\n\
+and\n\
+@smallexample\n\
+(set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)).\n\
+@end smallexample\n\
+to let the backend emit the call frame instructions.  @var{label} is\n\
+the CFI label attached to the insn, @var{pattern} is the pattern of\n\
+the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}.",
  void, (const char *label, rtx pattern, int index), NULL)
 
 /* ??? Documenting this hook requires a GFDL license grant.  */
@@ -2030,7 +3433,14 @@ 
    protection guard variable.  The type of this DECL is ptr_type_node.  */
 DEFHOOK
 (stack_protect_guard,
- "",
+ "This hook returns a @code{DECL} node for the external variable to use\n\
+for the stack protection guard.  This variable is initialized by the\n\
+runtime to some random value and is used to initialize the guard value\n\
+that is placed at the top of the local stack frame.  The type of this\n\
+variable must be @code{ptr_type_node}.\n\
+\n\
+The default version of this hook creates a variable called\n\
+@samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}.",
  tree, (void),
  default_stack_protect_guard)
 
@@ -2038,7 +3448,13 @@ 
    that is invoked when a check vs the guard variable fails.  */
 DEFHOOK
 (stack_protect_fail,
- "",
+ "This hook returns a @code{CALL_EXPR} that alerts the runtime that the\n\
+stack protect guard variable has been modified.  This expression should\n\
+involve a call to a @code{noreturn} function.\n\
+\n\
+The default version of this hook invokes a function called\n\
+@samp{__stack_chk_fail}, taking no arguments.  This function is\n\
+normally defined in @file{libgcc2.c}.",
  tree, (void),
  default_external_stack_protect_fail)
 
@@ -2046,7 +3462,16 @@ 
    otherwise it returns an error message.  */
 DEFHOOK
 (invalid_within_doloop,
- "",
+ "\n\
+Take an instruction in @var{insn} and return NULL if it is valid within a\n\
+low-overhead loop, otherwise return a string explaining why doloop\n\
+could not be applied.\n\
+\n\
+Many targets use special registers for low-overhead looping. For any\n\
+instruction that clobbers these this function should return a string indicating\n\
+the reason why the doloop could not be applied.\n\
+By default, the RTL loop optimizer does not use a present doloop pattern for\n\
+loops containing function calls or branch on table instructions.",
  const char *, (const_rtx insn),
  default_invalid_within_doloop)
 
@@ -2071,13 +3496,28 @@ 
    value.  */
 DEFHOOKPOD
 (const_anchor,
- "",
+ "On some architectures it can take multiple instructions to synthesize\n\
+a constant.  If there is another constant already in a register that\n\
+is close enough in value then it is preferable that the new constant\n\
+is computed from this register using immediate addition or\n\
+subtraction.  We accomplish this through CSE.  Besides the value of\n\
+the constant we also add a lower and an upper constant anchor to the\n\
+available expressions.  These are then queried when encountering new\n\
+constants.  The anchors are computed by rounding the constant up and\n\
+down to a multiple of the value of @code{TARGET_CONST_ANCHOR}.\n\
+@code{TARGET_CONST_ANCHOR} should be the maximum positive value\n\
+accepted by immediate-add plus one.  We currently assume that the\n\
+value of @code{TARGET_CONST_ANCHOR} is a power of 2.  For example, on\n\
+MIPS, where add-immediate takes a 16-bit signed value,\n\
+@code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}.  The default value\n\
+is zero, which disables this optimization.",
  unsigned HOST_WIDE_INT, 0)
 
 /* Defines, which target-dependent bits (upper 16) are used by port  */
 DEFHOOK
 (memmodel_check,
- "",
+ "Validate target specific memory model mask bits. When NULL no target specific\n\
+memory model bits are allowed.",
  unsigned HOST_WIDE_INT, (unsigned HOST_WIDE_INT val), NULL)
 
 /* Defines an offset bitwise ored into shifted address to get corresponding
@@ -2097,31 +3537,96 @@ 
 
 DEFHOOK
 (promote_function_mode,
- "",
+ "Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or\n\
+function return values.  The target hook should return the new mode\n\
+and possibly change @code{*@var{punsignedp}} if the promotion should\n\
+change signedness.  This function is called only for scalar @emph{or\n\
+pointer} types.\n\
+\n\
+@var{for_return} allows to distinguish the promotion of arguments and\n\
+return values.  If it is @code{1}, a return value is being promoted and\n\
+@code{TARGET_FUNCTION_VALUE} must perform the same promotions done here.\n\
+If it is @code{2}, the returned mode should be that of the register in\n\
+which an incoming parameter is copied, or the outgoing result is computed;\n\
+then the hook should return the same mode as @code{promote_mode}, though\n\
+the signedness may be different.\n\
+\n\
+@var{type} can be NULL when promoting function arguments of libcalls.\n\
+\n\
+The default is to not promote arguments and return values.  You can\n\
+also define the hook to @code{default_promote_function_mode_always_promote}\n\
+if you would like to apply the same rules given by @code{PROMOTE_MODE}.",
  enum machine_mode, (const_tree type, enum machine_mode mode, int *punsignedp,
 		     const_tree funtype, int for_return),
  default_promote_function_mode)
 
 DEFHOOK
 (promote_prototypes,
- "",
+ "This target hook returns @code{true} if an argument declared in a\n\
+prototype as an integral type smaller than @code{int} should actually be\n\
+passed as an @code{int}.  In addition to avoiding errors in certain\n\
+cases of mismatch, it also makes for better code on certain machines.\n\
+The default is to not promote prototypes.",
  bool, (const_tree fntype),
  hook_bool_const_tree_false)
 
 DEFHOOK
 (struct_value_rtx,
- "",
+ "This target hook should return the location of the structure value\n\
+address (normally a @code{mem} or @code{reg}), or 0 if the address is\n\
+passed as an ``invisible'' first argument.  Note that @var{fndecl} may\n\
+be @code{NULL}, for libcalls.  You do not need to define this target\n\
+hook if the address is always passed as an ``invisible'' first\n\
+argument.\n\
+\n\
+On some architectures the place where the structure value address\n\
+is found by the called function is not the same place that the\n\
+caller put it.  This can be due to register windows, or it could\n\
+be because the function prologue moves it to a different place.\n\
+@var{incoming} is @code{1} or @code{2} when the location is needed in\n\
+the context of the called function, and @code{0} in the context of\n\
+the caller.\n\
+\n\
+If @var{incoming} is nonzero and the address is to be found on the\n\
+stack, return a @code{mem} which refers to the frame pointer. If\n\
+@var{incoming} is @code{2}, the result is being used to fetch the\n\
+structure value address at the beginning of a function.  If you need\n\
+to emit adjusting code, you should do it at this point.",
  rtx, (tree fndecl, int incoming),
  hook_rtx_tree_int_null)
 DEFHOOK
 (return_in_memory,
- "",
+ "This target hook should return a nonzero value to say to return the\n\
+function value in memory, just as large structures are always returned.\n\
+Here @var{type} will be the data type of the value, and @var{fntype}\n\
+will be the type of the function doing the returning, or @code{NULL} for\n\
+libcalls.\n\
+\n\
+Note that values of mode @code{BLKmode} must be explicitly handled\n\
+by this function.  Also, the option @option{-fpcc-struct-return}\n\
+takes effect regardless of this macro.  On most systems, it is\n\
+possible to leave the hook undefined; this causes a default\n\
+definition to be used, whose value is the constant 1 for @code{BLKmode}\n\
+values, and 0 otherwise.\n\
+\n\
+Do not use this hook to indicate that structures and unions should always\n\
+be returned in memory.  You should instead use @code{DEFAULT_PCC_STRUCT_RETURN}\n\
+to indicate this.",
  bool, (const_tree type, const_tree fntype),
  default_return_in_memory)
 
 DEFHOOK
 (return_in_msb,
- "",
+ "This hook should return true if values of type @var{type} are returned\n\
+at the most significant end of a register (in other words, if they are\n\
+padded at the least significant end).  You can assume that @var{type}\n\
+is returned in a register; the caller is required to check this.\n\
+\n\
+Note that the register provided by @code{TARGET_FUNCTION_VALUE} must\n\
+be able to hold the complete return value.  For example, if a 1-, 2-\n\
+or 3-byte structure is returned at the most significant end of a\n\
+4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an\n\
+@code{SImode} rtx.",
  bool, (const_tree type),
  hook_bool_const_tree_false)
 
@@ -2130,28 +3635,81 @@ 
    from __builtin_va_arg.  */
 DEFHOOK
 (pass_by_reference,
- "",
+ "This target hook should return @code{true} if an argument at the\n\
+position indicated by @var{cum} should be passed by reference.  This\n\
+predicate is queried after target independent reasons for being\n\
+passed by reference, such as @code{TREE_ADDRESSABLE (type)}.\n\
+\n\
+If the hook returns true, a copy of that argument is made in memory and a\n\
+pointer to the argument is passed instead of the argument itself.\n\
+The pointer is passed in whatever way is appropriate for passing a pointer\n\
+to that type.",
  bool,
  (cumulative_args_t cum, enum machine_mode mode, const_tree type, bool named),
  hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
 
 DEFHOOK
 (expand_builtin_saveregs,
- "",
+ "If defined, this hook produces the machine-specific code for a call to\n\
+@code{__builtin_saveregs}.  This code will be moved to the very\n\
+beginning of the function, before any parameter access are made.  The\n\
+return value of this function should be an RTX that contains the value\n\
+to use as the return of @code{__builtin_saveregs}.",
  rtx, (void),
  default_expand_builtin_saveregs)
 
 /* Returns pretend_argument_size.  */
 DEFHOOK
 (setup_incoming_varargs,
- "",
+ "This target hook offers an alternative to using\n\
+@code{__builtin_saveregs} and defining the hook\n\
+@code{TARGET_EXPAND_BUILTIN_SAVEREGS}.  Use it to store the anonymous\n\
+register arguments into the stack so that all the arguments appear to\n\
+have been passed consecutively on the stack.  Once this is done, you can\n\
+use the standard implementation of varargs that works for machines that\n\
+pass all their arguments on the stack.\n\
+\n\
+The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data\n\
+structure, containing the values that are obtained after processing the\n\
+named arguments.  The arguments @var{mode} and @var{type} describe the\n\
+last named argument---its machine mode and its data type as a tree node.\n\
+\n\
+The target hook should do two things: first, push onto the stack all the\n\
+argument registers @emph{not} used for the named arguments, and second,\n\
+store the size of the data thus pushed into the @code{int}-valued\n\
+variable pointed to by @var{pretend_args_size}.  The value that you\n\
+store here will serve as additional offset for setting up the stack\n\
+frame.\n\
+\n\
+Because you must generate code to push the anonymous arguments at\n\
+compile time without knowing their data types,\n\
+@code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that\n\
+have just a single category of argument register and use it uniformly\n\
+for all data types.\n\
+\n\
+If the argument @var{second_time} is nonzero, it means that the\n\
+arguments of the function are being analyzed for the second time.  This\n\
+happens for an inline function, which is not actually compiled until the\n\
+end of the source file.  The hook @code{TARGET_SETUP_INCOMING_VARARGS} should\n\
+not generate any instructions in this case.",
  void, (cumulative_args_t args_so_far, enum machine_mode mode, tree type,
 	int *pretend_args_size, int second_time),
  default_setup_incoming_varargs)
 
 DEFHOOK
 (strict_argument_naming,
- "",
+ "Define this hook to return @code{true} if the location where a function\n\
+argument is passed depends on whether or not it is a named argument.\n\
+\n\
+This hook controls how the @var{named} argument to @code{TARGET_FUNCTION_ARG}\n\
+is set for varargs and stdarg functions.  If this hook returns\n\
+@code{true}, the @var{named} argument is always true for named\n\
+arguments, and false for unnamed arguments.  If it returns @code{false},\n\
+but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true},\n\
+then all arguments are treated as named.  Otherwise, all named arguments\n\
+except the last are treated as named.\n\
+\n\
+You need not define this hook if it always returns @code{false}.",
  bool, (cumulative_args_t ca),
  hook_bool_CUMULATIVE_ARGS_false)
 
@@ -2160,7 +3718,12 @@ 
    targetm.calls.strict_argument_naming().  */
 DEFHOOK
 (pretend_outgoing_varargs_named,
- "",
+ "If you need to conditionally change ABIs so that one works with\n\
+@code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither\n\
+@code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was\n\
+defined, then define this hook to return @code{true} if\n\
+@code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise.\n\
+Otherwise, you should not define this hook.",
  bool, (cumulative_args_t ca),
  default_pretend_outgoing_varargs_named)
 
@@ -2168,7 +3731,16 @@ 
    should be passed as two scalars.  */
 DEFHOOK
 (split_complex_arg,
- "",
+ "This hook should return true if parameter of type @var{type} are passed\n\
+as two scalar parameters.  By default, GCC will attempt to pack complex\n\
+arguments into the target's word size.  Some ABIs require complex arguments\n\
+to be split and treated as their individual components.  For example, on\n\
+AIX64, complex floats should be passed in a pair of floating point\n\
+registers, even though a complex float would fit in one 64-bit floating\n\
+point register.\n\
+\n\
+The default value of this hook is @code{NULL}, which is treated as always\n\
+false.",
  bool, (const_tree type), NULL)
 
 /* Return true if type T, mode MODE, may not be passed in registers,
@@ -2177,7 +3749,10 @@ 
    Need audit to verify that this is the case.  */
 DEFHOOK
 (must_pass_in_stack,
- "",
+ "This target hook should return @code{true} if we should not pass @var{type}\n\
+solely in registers.  The file @file{expr.h} defines a\n\
+definition that is usually appropriate, refer to @file{expr.h} for additional\n\
+documentation.",
  bool, (enum machine_mode mode, const_tree type),
  must_pass_in_stack_var_size_or_pad)
 
@@ -2186,7 +3761,16 @@ 
    the caller.  It is never called for TYPE requiring constructors.  */
 DEFHOOK
 (callee_copies,
- "",
+ "The function argument described by the parameters to this hook is\n\
+known to be passed by reference.  The hook should return true if the\n\
+function argument should be copied by the callee instead of copied\n\
+by the caller.\n\
+\n\
+For any argument for which the hook returns true, if it can be\n\
+determined that the argument is not modified, then a copy need\n\
+not be generated.\n\
+\n\
+The default version of this hook always returns false.",
  bool,
  (cumulative_args_t cum, enum machine_mode mode, const_tree type, bool named),
  hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
@@ -2196,7 +3780,22 @@ 
    in registers; the balance is therefore passed on the stack.  */
 DEFHOOK
 (arg_partial_bytes,
- "",
+ "This target hook returns the number of bytes at the beginning of an\n\
+argument that must be put in registers.  The value must be zero for\n\
+arguments that are passed entirely in registers or that are entirely\n\
+pushed on the stack.\n\
+\n\
+On some machines, certain arguments must be passed partially in\n\
+registers and partially in memory.  On these machines, typically the\n\
+first few words of arguments are passed in registers, and the rest\n\
+on the stack.  If a multi-word argument (a @code{double} or a\n\
+structure) crosses that boundary, its first few words must be passed\n\
+in registers and the rest must be pushed.  This macro tells the\n\
+compiler when this occurs, and how many bytes should go in registers.\n\
+\n\
+@code{TARGET_FUNCTION_ARG} for these arguments should return the first\n\
+register to be used by the caller for this argument; likewise\n\
+@code{TARGET_FUNCTION_INCOMING_ARG}, for the called function.",
  int, (cumulative_args_t cum, enum machine_mode mode, tree type, bool named),
  hook_int_CUMULATIVE_ARGS_mode_tree_bool_0)
 
@@ -2205,7 +3804,15 @@ 
    argument.  */
 DEFHOOK
 (function_arg_advance,
- "",
+ "This hook updates the summarizer variable pointed to by @var{ca} to\n\
+advance past an argument in the argument list.  The values @var{mode},\n\
+@var{type} and @var{named} describe that argument.  Once this is done,\n\
+the variable @var{cum} is suitable for analyzing the @emph{following}\n\
+argument with @code{TARGET_FUNCTION_ARG}, etc.\n\
+\n\
+This hook need not do anything if the argument in question was passed\n\
+on the stack.  The compiler knows how to track the amount of stack space\n\
+used for arguments without any special help.",
  void,
  (cumulative_args_t ca, enum machine_mode mode, const_tree type, bool named),
  default_function_arg_advance)
@@ -2216,7 +3823,56 @@ 
    argument.  */
 DEFHOOK
 (function_arg,
- "",
+ "Return an RTX indicating whether a function argument is passed in a\n\
+register and if so, which register.\n\
+\n\
+The arguments are @var{ca}, which summarizes all the previous\n\
+arguments; @var{mode}, the machine mode of the argument; @var{type},\n\
+the data type of the argument as a tree node or 0 if that is not known\n\
+(which happens for C support library functions); and @var{named},\n\
+which is @code{true} for an ordinary argument and @code{false} for\n\
+nameless arguments that correspond to @samp{@dots{}} in the called\n\
+function's prototype.  @var{type} can be an incomplete type if a\n\
+syntax error has previously occurred.\n\
+\n\
+The return value is usually either a @code{reg} RTX for the hard\n\
+register in which to pass the argument, or zero to pass the argument\n\
+on the stack.\n\
+\n\
+The value of the expression can also be a @code{parallel} RTX@.  This is\n\
+used when an argument is passed in multiple locations.  The mode of the\n\
+@code{parallel} should be the mode of the entire argument.  The\n\
+@code{parallel} holds any number of @code{expr_list} pairs; each one\n\
+describes where part of the argument is passed.  In each\n\
+@code{expr_list} the first operand must be a @code{reg} RTX for the hard\n\
+register in which to pass this part of the argument, and the mode of the\n\
+register RTX indicates how large this part of the argument is.  The\n\
+second operand of the @code{expr_list} is a @code{const_int} which gives\n\
+the offset in bytes into the entire argument of where this part starts.\n\
+As a special exception the first @code{expr_list} in the @code{parallel}\n\
+RTX may have a first operand of zero.  This indicates that the entire\n\
+argument is also stored on the stack.\n\
+\n\
+The last time this hook is called, it is called with @code{MODE ==\n\
+VOIDmode}, and its result is passed to the @code{call} or @code{call_value}\n\
+pattern as operands 2 and 3 respectively.\n\
+\n\
+@cindex @file{stdarg.h} and register arguments\n\
+The usual way to make the ISO library @file{stdarg.h} work on a\n\
+machine where some arguments are usually passed in registers, is to\n\
+cause nameless arguments to be passed on the stack instead.  This is\n\
+done by making @code{TARGET_FUNCTION_ARG} return 0 whenever\n\
+@var{named} is @code{false}.\n\
+\n\
+@cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{TARGET_FUNCTION_ARG}\n\
+@cindex @code{REG_PARM_STACK_SPACE}, and @code{TARGET_FUNCTION_ARG}\n\
+You may use the hook @code{targetm.calls.must_pass_in_stack}\n\
+in the definition of this macro to determine if this argument is of a\n\
+type that must be passed in the stack.  If @code{REG_PARM_STACK_SPACE}\n\
+is not defined and @code{TARGET_FUNCTION_ARG} returns nonzero for such an\n\
+argument, the compiler will abort.  If @code{REG_PARM_STACK_SPACE} is\n\
+defined, the argument will be computed in the stack and then loaded into\n\
+a register.",
  rtx, (cumulative_args_t ca, enum machine_mode mode, const_tree type,
        bool named),
  default_function_arg)
@@ -2225,14 +3881,28 @@ 
    location where the argument will appear to the callee.  */
 DEFHOOK
 (function_incoming_arg,
- "",
+ "Define this hook if the target machine has ``register windows'', so\n\
+that the register in which a function sees an arguments is not\n\
+necessarily the same as the one in which the caller passed the\n\
+argument.\n\
+\n\
+For such machines, @code{TARGET_FUNCTION_ARG} computes the register in\n\
+which the caller passes the value, and\n\
+@code{TARGET_FUNCTION_INCOMING_ARG} should be defined in a similar\n\
+fashion to tell the function being called where the arguments will\n\
+arrive.\n\
+\n\
+If @code{TARGET_FUNCTION_INCOMING_ARG} is not defined,\n\
+@code{TARGET_FUNCTION_ARG} serves both purposes.",
  rtx, (cumulative_args_t ca, enum machine_mode mode, const_tree type,
        bool named),
  default_function_incoming_arg)
 
 DEFHOOK
 (function_arg_boundary,
- "",
+ "This hook returns the alignment boundary, in bits, of an argument\n\
+with the specified mode and type.  The default hook returns\n\
+@code{PARM_BOUNDARY} for all arguments.",
  unsigned int, (enum machine_mode mode, const_tree type),
  default_function_arg_boundary)
 
@@ -2249,7 +3919,9 @@ 
    is not allowed for this 'val' argument; NULL otherwise. */
 DEFHOOK
 (invalid_arg_for_unprototyped_fn,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+illegal to pass argument @var{val} to function @var{funcdecl}\n\
+with prototype @var{typelist}.",
  const char *, (const_tree typelist, const_tree funcdecl, const_tree val),
  hook_invalid_arg_for_unprototyped_fn)
 
@@ -2257,7 +3929,47 @@ 
    specified by FN_DECL_OR_TYPE with a return type of RET_TYPE.  */
 DEFHOOK
 (function_value,
- "",
+ "\n\
+Define this to return an RTX representing the place where a function\n\
+returns or receives a value of data type @var{ret_type}, a tree node\n\
+representing a data type.  @var{fn_decl_or_type} is a tree node\n\
+representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a\n\
+function being called.  If @var{outgoing} is false, the hook should\n\
+compute the register in which the caller will see the return value.\n\
+Otherwise, the hook should return an RTX representing the place where\n\
+a function returns a value.\n\
+\n\
+On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant.\n\
+(Actually, on most machines, scalar values are returned in the same\n\
+place regardless of mode.)  The value of the expression is usually a\n\
+@code{reg} RTX for the hard register where the return value is stored.\n\
+The value can also be a @code{parallel} RTX, if the return value is in\n\
+multiple places.  See @code{TARGET_FUNCTION_ARG} for an explanation of the\n\
+@code{parallel} form.   Note that the callee will populate every\n\
+location specified in the @code{parallel}, but if the first element of\n\
+the @code{parallel} contains the whole return value, callers will use\n\
+that element as the canonical location and ignore the others.  The m68k\n\
+port uses this type of @code{parallel} to return pointers in both\n\
+@samp{%a0} (the canonical location) and @samp{%d0}.\n\
+\n\
+If @code{TARGET_PROMOTE_FUNCTION_RETURN} returns true, you must apply\n\
+the same promotion rules specified in @code{PROMOTE_MODE} if\n\
+@var{valtype} is a scalar type.\n\
+\n\
+If the precise function being called is known, @var{func} is a tree\n\
+node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null\n\
+pointer.  This makes it possible to use a different value-returning\n\
+convention for specific functions when all their calls are\n\
+known.\n\
+\n\
+Some target machines have ``register windows'' so that the register in\n\
+which a function returns its value is not the same as the one in which\n\
+the caller sees the value.  For such machines, you should return\n\
+different RTX depending on @var{outgoing}.\n\
+\n\
+@code{TARGET_FUNCTION_VALUE} is not used for return values with\n\
+aggregate data types, because these are returned in another way.  See\n\
+@code{TARGET_STRUCT_VALUE_RTX} and related macros, below.",
  rtx, (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing),
  default_function_value)
 
@@ -2265,7 +3977,14 @@ 
    calling the function FN_NAME.  */
 DEFHOOK
 (libcall_value,
- "",
+ "Define this hook if the back-end needs to know the name of the libcall\n\
+function in order to determine where the result should be returned.\n\
+\n\
+The mode of the result is given by @var{mode} and the name of the called\n\
+library function is given by @var{fun}.  The hook should return an RTX\n\
+representing the place where the library function result will be returned.\n\
+\n\
+If this hook is not defined, then LIBCALL_VALUE will be used.",
  rtx, (enum machine_mode mode, const_rtx fun),
  default_libcall_value)
 
@@ -2273,7 +3992,18 @@ 
    a function value as seen by the caller.  */
 DEFHOOK
 (function_value_regno_p,
- "",
+ "A target hook that return @code{true} if @var{regno} is the number of a hard\n\
+register in which the values of called function may come back.\n\
+\n\
+A register whose use for returning values is limited to serving as the\n\
+second of a pair (for a value of type @code{double}, say) need not be\n\
+recognized by this target hook.\n\
+\n\
+If the machine has register windows, so that the caller and the called\n\
+function use different registers for the return value, this target hook\n\
+should recognize only the caller's register numbers.\n\
+\n\
+If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.",
  bool, (const unsigned int regno),
  default_function_value_regno_p)
 
@@ -2288,21 +4018,32 @@ 
 /* Update the current function stack boundary if needed.  */
 DEFHOOK
 (update_stack_boundary,
- "",
+ "Define this macro to update the current function stack boundary if\n\
+necessary.",
  void, (void), NULL)
 
 /* Handle stack alignment and return an rtx for Dynamic Realign
    Argument Pointer if necessary.  */
 DEFHOOK
 (get_drap_rtx,
- "",
+ "This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a\n\
+different argument pointer register is needed to access the function's\n\
+argument list due to stack realignment.  Return @code{NULL} if no DRAP\n\
+is needed.",
  rtx, (void), NULL)
 
 /* Return true if all function parameters should be spilled to the
    stack.  */
 DEFHOOK
 (allocate_stack_slots_for_args,
- "",
+ "When optimization is disabled, this hook indicates whether or not\n\
+arguments should be allocated to stack slots.  Normally, GCC allocates\n\
+stacks slots for arguments when not optimizing in order to make\n\
+debugging easier.  However, when a function is declared with\n\
+@code{__attribute__((naked))}, there is no stack frame, and the compiler\n\
+cannot safely move arguments from the registers in which they are passed\n\
+to the stack.  Therefore, this hook should return true in general, but\n\
+false for naked functions.  The default implementation always returns true.",
  bool, (void),
  hook_bool_void_true)
 
@@ -2310,7 +4051,25 @@ 
        then it should be for the callee; otherwise for the caller.  */
 DEFHOOK
 (static_chain,
- "",
+ "This hook replaces the use of @code{STATIC_CHAIN_REGNUM} et al for\n\
+targets that may use different static chain locations for different\n\
+nested functions.  This may be required if the target has function\n\
+attributes that affect the calling conventions of the function and\n\
+those calling conventions use different static chain locations.\n\
+\n\
+The default version of this hook uses @code{STATIC_CHAIN_REGNUM} et al.\n\
+\n\
+If the static chain is passed in memory, this hook should be used to\n\
+provide rtx giving @code{mem} expressions that denote where they are stored.\n\
+Often the @code{mem} expression as seen by the caller will be at an offset\n\
+from the stack pointer and the @code{mem} expression as seen by the callee\n\
+will be at an offset from the frame pointer.\n\
+@findex stack_pointer_rtx\n\
+@findex frame_pointer_rtx\n\
+@findex arg_pointer_rtx\n\
+The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and\n\
+@code{arg_pointer_rtx} will have been initialized and should be used\n\
+to refer to those items.",
  rtx, (const_tree fndecl, bool incoming_p),
  default_static_chain)
 
@@ -2318,14 +4077,35 @@ 
    static chain value of CHAIN.  */
 DEFHOOK
 (trampoline_init,
- "",
+ "This hook is called to initialize a trampoline.\n\
+@var{m_tramp} is an RTX for the memory block for the trampoline; @var{fndecl}\n\
+is the @code{FUNCTION_DECL} for the nested function; @var{static_chain} is an\n\
+RTX for the static chain value that should be passed to the function\n\
+when it is called.\n\
+\n\
+If the target defines @code{TARGET_ASM_TRAMPOLINE_TEMPLATE}, then the\n\
+first thing this hook should do is emit a block move into @var{m_tramp}\n\
+from the memory block returned by @code{assemble_trampoline_template}.\n\
+Note that the block move need only cover the constant parts of the\n\
+trampoline.  If the target isolates the variable parts of the trampoline\n\
+to the end, not all @code{TRAMPOLINE_SIZE} bytes need be copied.\n\
+\n\
+If the target requires any other actions, such as flushing caches or\n\
+enabling stack execution, these actions should be performed after\n\
+initializing the trampoline proper.",
  void, (rtx m_tramp, tree fndecl, rtx static_chain),
  default_trampoline_init)
 
 /* Adjust the address of the trampoline in a target-specific way.  */
 DEFHOOK
 (trampoline_adjust_address,
- "",
+ "This hook should perform any machine-specific adjustment in\n\
+the address of the trampoline.  Its argument contains the address of the\n\
+memory block that was passed to @code{TARGET_TRAMPOLINE_INIT}.  In case\n\
+the address to be used for a function call should be different from the\n\
+address at which the template was stored, the different address should\n\
+be returned; otherwise @var{addr} should be returned unchanged.\n\
+If this hook is not defined, @var{addr} will be used for function calls.",
  rtx, (rtx addr), NULL)
 
 /* Return the number of bytes of its own arguments that a function
@@ -2334,7 +4114,41 @@ 
 /* ??? tm.texi has no types for the parameters.  */
 DEFHOOK
 (return_pops_args,
- "",
+ "This target hook returns the number of bytes of its own arguments that\n\
+a function pops on returning, or 0 if the function pops no arguments\n\
+and the caller must therefore pop them all after the function returns.\n\
+\n\
+@var{fundecl} is a C variable whose value is a tree node that describes\n\
+the function in question.  Normally it is a node of type\n\
+@code{FUNCTION_DECL} that describes the declaration of the function.\n\
+From this you can obtain the @code{DECL_ATTRIBUTES} of the function.\n\
+\n\
+@var{funtype} is a C variable whose value is a tree node that\n\
+describes the function in question.  Normally it is a node of type\n\
+@code{FUNCTION_TYPE} that describes the data type of the function.\n\
+From this it is possible to obtain the data types of the value and\n\
+arguments (if known).\n\
+\n\
+When a call to a library function is being considered, @var{fundecl}\n\
+will contain an identifier node for the library function.  Thus, if\n\
+you need to distinguish among various library functions, you can do so\n\
+by their names.  Note that ``library function'' in this context means\n\
+a function used to perform arithmetic, whose name is known specially\n\
+in the compiler and was not mentioned in the C code being compiled.\n\
+\n\
+@var{size} is the number of bytes of arguments passed on the\n\
+stack.  If a variable number of bytes is passed, it is zero, and\n\
+argument popping will always be the responsibility of the calling function.\n\
+\n\
+On the VAX, all functions always pop their arguments, so the definition\n\
+of this macro is @var{size}.  On the 68000, using the standard\n\
+calling convention, no functions pop their arguments, so the value of\n\
+the macro is always 0 in this case.  But an alternative calling\n\
+convention is available in which functions that take a fixed number of\n\
+arguments pop them but other functions (such as @code{printf}) pop\n\
+nothing (the caller pops all).  When this convention is in use,\n\
+@var{funtype} is examined to determine whether a function takes a fixed\n\
+number of arguments.",
  int, (tree fundecl, tree funtype, int size),
  default_return_pops_args)
 
@@ -2364,7 +4178,9 @@ 
    to TOTYPE is not allowed, NULL otherwise.  */
 DEFHOOK
 (invalid_conversion,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL}\n\
+if validity should be determined by the front end.",
  const char *, (const_tree fromtype, const_tree totype),
  hook_constcharptr_const_tree_const_tree_null)
 
@@ -2372,7 +4188,10 @@ 
    not permitted on TYPE, NULL otherwise.  */
 DEFHOOK
 (invalid_unary_op,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+invalid to apply operation @var{op} (where unary plus is denoted by\n\
+@code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL}\n\
+if validity should be determined by the front end.",
  const char *, (int op, const_tree type),
  hook_constcharptr_int_const_tree_null)
 
@@ -2380,7 +4199,10 @@ 
    is not permitted on TYPE1 and TYPE2, NULL otherwise.  */
 DEFHOOK
 (invalid_binary_op,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+invalid to apply operation @var{op} to operands of types @var{type1}\n\
+and @var{type2}, or @code{NULL} if validity should be determined by\n\
+the front end.",
  const char *, (int op, const_tree type1, const_tree type2),
  hook_constcharptr_int_const_tree_const_tree_null)
 
@@ -2388,7 +4210,10 @@ 
    function parameter type, NULL otherwise.  */
 DEFHOOK
 (invalid_parameter_type,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+invalid for functions to include parameters of type @var{type},\n\
+or @code{NULL} if validity should be determined by\n\
+the front end.  This is currently used only by the C and C++ front ends.",
  const char *, (const_tree type),
  hook_constcharptr_const_tree_null)
 
@@ -2396,7 +4221,10 @@ 
    function return type, NULL otherwise.  */
 DEFHOOK
 (invalid_return_type,
- "",
+ "If defined, this macro returns the diagnostic message when it is\n\
+invalid for functions to have return type @var{type},\n\
+or @code{NULL} if validity should be determined by\n\
+the front end.  This is currently used only by the C and C++ front ends.",
  const char *, (const_tree type),
  hook_constcharptr_const_tree_null)
 
@@ -2405,7 +4233,12 @@ 
    or NULL_TREE otherwise.  */
 DEFHOOK
 (promoted_type,
- "",
+ "If defined, this target hook returns the type to which values of\n\
+@var{type} should be promoted when they appear in expressions,\n\
+analogous to the integer promotions, or @code{NULL_TREE} to use the\n\
+front end's normal promotion rules.  This hook is useful when there are\n\
+target-specific types with special promotion rules.\n\
+This is currently used only by the C and C++ front ends.",
  tree, (const_tree type),
  hook_tree_const_tree_null)
 
@@ -2414,7 +4247,12 @@ 
    the standard conversion rules.  */
 DEFHOOK
 (convert_to_type,
- "",
+ "If defined, this hook returns the result of converting @var{expr} to\n\
+@var{type}.  It should return the converted expression,\n\
+or @code{NULL_TREE} to apply the front end's normal conversion rules.\n\
+This hook is useful when there are target-specific types with special\n\
+conversion rules.\n\
+This is currently used only by the C and C++ front ends.",
  tree, (tree type, tree expr),
  hook_tree_tree_tree_null)
 
@@ -2496,14 +4334,104 @@ 
    be accessed using BLKmode.  */
 DEFHOOK
 (member_type_forces_blk,
- "",
+ "Return true if a structure, union or array containing @var{field} should\n\
+be accessed using @code{BLKMODE}.\n\
+\n\
+If @var{field} is the only field in the structure, @var{mode} is its\n\
+mode, otherwise @var{mode} is VOIDmode.  @var{mode} is provided in the\n\
+case where structures of one field would require the structure's mode to\n\
+retain the field's mode.\n\
+\n\
+Normally, this is not needed.",
  bool, (const_tree field, enum machine_mode mode),
  default_member_type_forces_blk)
 
 /* Return the class for a secondary reload, and fill in extra information.  */
 DEFHOOK
 (secondary_reload,
- "",
+ "Many machines have some registers that cannot be copied directly to or\n\
+from memory or even from other types of registers.  An example is the\n\
+@samp{MQ} register, which on most machines, can only be copied to or\n\
+from general registers, but not memory.  Below, we shall be using the\n\
+term 'intermediate register' when a move operation cannot be performed\n\
+directly, but has to be done by copying the source into the intermediate\n\
+register first, and then copying the intermediate register to the\n\
+destination.  An intermediate register always has the same mode as\n\
+source and destination.  Since it holds the actual value being copied,\n\
+reload might apply optimizations to re-use an intermediate register\n\
+and eliding the copy from the source when it can determine that the\n\
+intermediate register still holds the required value.\n\
+\n\
+Another kind of secondary reload is required on some machines which\n\
+allow copying all registers to and from memory, but require a scratch\n\
+register for stores to some memory locations (e.g., those with symbolic\n\
+address on the RT, and those with certain symbolic address on the SPARC\n\
+when compiling PIC)@.  Scratch registers need not have the same mode\n\
+as the value being copied, and usually hold a different value than\n\
+that being copied.  Special patterns in the md file are needed to\n\
+describe how the copy is performed with the help of the scratch register;\n\
+these patterns also describe the number, register class(es) and mode(s)\n\
+of the scratch register(s).\n\
+\n\
+In some cases, both an intermediate and a scratch register are required.\n\
+\n\
+For input reloads, this target hook is called with nonzero @var{in_p},\n\
+and @var{x} is an rtx that needs to be copied to a register of class\n\
+@var{reload_class} in @var{reload_mode}.  For output reloads, this target\n\
+hook is called with zero @var{in_p}, and a register of class @var{reload_class}\n\
+needs to be copied to rtx @var{x} in @var{reload_mode}.\n\
+\n\
+If copying a register of @var{reload_class} from/to @var{x} requires\n\
+an intermediate register, the hook @code{secondary_reload} should\n\
+return the register class required for this intermediate register.\n\
+If no intermediate register is required, it should return NO_REGS.\n\
+If more than one intermediate register is required, describe the one\n\
+that is closest in the copy chain to the reload register.\n\
+\n\
+If scratch registers are needed, you also have to describe how to\n\
+perform the copy from/to the reload register to/from this\n\
+closest intermediate register.  Or if no intermediate register is\n\
+required, but still a scratch register is needed, describe the\n\
+copy  from/to the reload register to/from the reload operand @var{x}.\n\
+\n\
+You do this by setting @code{sri->icode} to the instruction code of a pattern\n\
+in the md file which performs the move.  Operands 0 and 1 are the output\n\
+and input of this copy, respectively.  Operands from operand 2 onward are\n\
+for scratch operands.  These scratch operands must have a mode, and a\n\
+single-register-class\n\
+@c [later: or memory]\n\
+output constraint.\n\
+\n\
+When an intermediate register is used, the @code{secondary_reload}\n\
+hook will be called again to determine how to copy the intermediate\n\
+register to/from the reload operand @var{x}, so your hook must also\n\
+have code to handle the register class of the intermediate operand.\n\
+\n\
+@c [For later: maybe we'll allow multi-alternative reload patterns -\n\
+@c   the port maintainer could name a mov<mode> pattern that has clobbers -\n\
+@c   and match the constraints of input and output to determine the required\n\
+@c   alternative.  A restriction would be that constraints used to match\n\
+@c   against reloads registers would have to be written as register class\n\
+@c   constraints, or we need a new target macro / hook that tells us if an\n\
+@c   arbitrary constraint can match an unknown register of a given class.\n\
+@c   Such a macro / hook would also be useful in other places.]\n\
+\n\
+\n\
+@var{x} might be a pseudo-register or a @code{subreg} of a\n\
+pseudo-register, which could either be in a hard register or in memory.\n\
+Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is\n\
+in memory and the hard register number if it is in a register.\n\
+\n\
+Scratch operands in memory (constraint @code{\"=m\"} / @code{\"=&m\"}) are\n\
+currently not supported.  For the time being, you will have to continue\n\
+to use @code{SECONDARY_MEMORY_NEEDED} for that purpose.\n\
+\n\
+@code{copy_cost} also uses this target hook to find out how values are\n\
+copied.  If you want it to include some extra cost for the need to allocate\n\
+(a) scratch register(s), set @code{sri->extra_cost} to the additional cost.\n\
+Or if two dependent moves are supposed to have a lower cost than the sum\n\
+of the individual moves due to expected fortuitous scheduling and/or special\n\
+forwarding logic, you can set @code{sri->extra_cost} to a negative amount.",
  reg_class_t,
  (bool in_p, rtx x, reg_class_t reload_class, enum machine_mode reload_mode,
   secondary_reload_info *sri),
@@ -2513,7 +4441,37 @@ 
    return the class of reg to actually use.  */
 DEFHOOK
 (preferred_reload_class,
- "",
+ "A target hook that places additional restrictions on the register class\n\
+to use when it is necessary to copy value @var{x} into a register in class\n\
+@var{rclass}.  The value is a register class; perhaps @var{rclass}, or perhaps\n\
+another, smaller class.\n\
+\n\
+The default version of this hook always returns value of @code{rclass} argument.\n\
+\n\
+Sometimes returning a more restrictive class makes better code.  For\n\
+example, on the 68000, when @var{x} is an integer constant that is in range\n\
+for a @samp{moveq} instruction, the value of this macro is always\n\
+@code{DATA_REGS} as long as @var{rclass} includes the data registers.\n\
+Requiring a data register guarantees that a @samp{moveq} will be used.\n\
+\n\
+One case where @code{TARGET_PREFERRED_RELOAD_CLASS} must not return\n\
+@var{rclass} is if @var{x} is a legitimate constant which cannot be\n\
+loaded into some register class.  By returning @code{NO_REGS} you can\n\
+force @var{x} into a memory location.  For example, rs6000 can load\n\
+immediate values into general-purpose registers, but does not have an\n\
+instruction for loading an immediate value into a floating-point\n\
+register, so @code{TARGET_PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when\n\
+@var{x} is a floating-point constant.  If the constant can't be loaded\n\
+into any kind of register, code generation will be better if\n\
+@code{TARGET_LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead\n\
+of using @code{TARGET_PREFERRED_RELOAD_CLASS}.\n\
+\n\
+If an insn has pseudos in it after register allocation, reload will go\n\
+through the alternatives and call repeatedly @code{TARGET_PREFERRED_RELOAD_CLASS}\n\
+to find the best one.  Returning @code{NO_REGS}, in this case, makes\n\
+reload add a @code{!} in front of the constraint: the x86 back-end uses\n\
+this feature to discourage usage of 387 registers when math is done in\n\
+the SSE registers (and vice versa).",
  reg_class_t,
  (rtx x, reg_class_t rclass),
  default_preferred_reload_class)
@@ -2522,14 +4480,33 @@ 
    input reloads.  */
 DEFHOOK
 (preferred_output_reload_class,
- "",
+ "Like @code{TARGET_PREFERRED_RELOAD_CLASS}, but for output reloads instead of\n\
+input reloads.\n\
+\n\
+The default version of this hook always returns value of @code{rclass}\n\
+argument.\n\
+\n\
+You can also use @code{TARGET_PREFERRED_OUTPUT_RELOAD_CLASS} to discourage\n\
+reload from using some alternatives, like @code{TARGET_PREFERRED_RELOAD_CLASS}.",
  reg_class_t,
  (rtx x, reg_class_t rclass),
  default_preferred_output_reload_class)
 
 DEFHOOK
 (class_likely_spilled_p,
- "",
+ "A target hook which returns @code{true} if pseudos that have been assigned\n\
+to registers of class @var{rclass} would likely be spilled because\n\
+registers of @var{rclass} are needed for spill registers.\n\
+\n\
+The default version of this target hook returns @code{true} if @var{rclass}\n\
+has exactly one register and @code{false} otherwise.  On most machines, this\n\
+default should be used.  For generally register-starved machines, such as\n\
+i386, or machines with right register constraints, such as SH, this hook\n\
+can be used to avoid excessive spilling.\n\
+\n\
+This hook is also used by some of the global intra-procedural code\n\
+transformations to throtle code motion, to avoid increasing register\n\
+pressure.",
  bool, (reg_class_t rclass),
  default_class_likely_spilled_p)
 
@@ -2537,7 +4514,20 @@ 
    needed to represent mode MODE in a register of class RCLASS.  */
 DEFHOOK
 (class_max_nregs,
- "",
+ "A target hook returns the maximum number of consecutive registers\n\
+of class @var{rclass} needed to hold a value of mode @var{mode}.\n\
+\n\
+This is closely related to the macro @code{HARD_REGNO_NREGS}.  In fact,\n\
+the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass},\n\
+@var{mode})} target hook should be the maximum value of\n\
+@code{HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno}\n\
+values in the class @var{rclass}.\n\
+\n\
+This target hook helps control the handling of multiple-word values\n\
+in the reload pass.\n\
+\n\
+The default version of this target hook returns the size of @var{mode}\n\
+in words.",
  unsigned char, (reg_class_t rclass, enum machine_mode mode),
  default_class_max_nregs)
 
@@ -2560,7 +4550,12 @@ 
    processing while initializing for variable expansion.  */
 DEFHOOK
 (expand_to_rtl_hook,
- "",
+ "This hook is called just before expansion into rtl, allowing the target\n\
+to perform additional initializations or analysis before the expansion.\n\
+For example, the rs6000 port uses it to allocate a scratch stack slot\n\
+for use in copying SDmode values between memory and floating point\n\
+registers whenever the function being expanded has any SDmode\n\
+usage.",
  void, (void),
  hook_void_void)
 
@@ -2569,7 +4564,8 @@ 
    but will be later.  */
 DEFHOOK
 (instantiate_decls,
- "",
+ "This hook allows the backend to perform additional instantiations on rtl\n\
+that are not actually in any insns yet, but will be later.",
  void, (void),
  hook_void_void)
 
@@ -2577,7 +4573,13 @@ 
    in peephole2.  */
 DEFHOOK
 (hard_regno_scratch_ok,
- "",
+ "This target hook should return @code{true} if it is OK to use a hard register\n\
+@var{regno} as scratch reg in peephole2.\n\
+\n\
+One common use of this macro is to prevent using of a register that\n\
+is not saved by a prologue in an interrupt handler.\n\
+\n\
+The default version of this hook always returns @code{true}.",
  bool, (unsigned int regno),
  default_hard_regno_scratch_ok)
 
@@ -2585,14 +4587,38 @@ 
    use a jump-table instead of a tree of conditional branches.  */
 DEFHOOK
 (case_values_threshold,
- "",
+ "This function return the smallest number of different values for which it\n\
+is best to use a jump-table instead of a tree of conditional branches.\n\
+The default is four for machines with a @code{casesi} instruction and\n\
+five otherwise.  This is best for most machines.",
  unsigned int, (void),
  default_case_values_threshold)
 
 /* Retutn true if a function must have and use a frame pointer.  */
 DEFHOOK
 (frame_pointer_required,
- "",
+ "This target hook should return @code{true} if a function must have and use\n\
+a frame pointer.  This target hook is called in the reload pass.  If its return\n\
+value is @code{true} the function will have a frame pointer.\n\
+\n\
+This target hook can in principle examine the current function and decide\n\
+according to the facts, but on most machines the constant @code{false} or the\n\
+constant @code{true} suffices.  Use @code{false} when the machine allows code\n\
+to be generated with no frame pointer, and doing so saves some time or space.\n\
+Use @code{true} when there is no possible advantage to avoiding a frame\n\
+pointer.\n\
+\n\
+In certain cases, the compiler does not know how to produce valid code\n\
+without a frame pointer.  The compiler recognizes those cases and\n\
+automatically gives the function a frame pointer regardless of what\n\
+@code{TARGET_FRAME_POINTER_REQUIRED} returns.  You don't need to worry about\n\
+them.\n\
+\n\
+In a function that does not require a frame pointer, the frame pointer\n\
+register can be allocated for ordinary usage, unless you mark it as a\n\
+fixed register.  See @code{FIXED_REGISTERS} for more information.\n\
+\n\
+Default return value is @code{false}.",
  bool, (void),
  hook_bool_void_false)
 
@@ -2600,7 +4626,14 @@ 
    from-reg with register number to-reg.  */
 DEFHOOK
 (can_eliminate,
- "",
+ "This target hook should returns @code{true} if the compiler is allowed to\n\
+try to replace register number @var{from_reg} with register number\n\
+@var{to_reg}.  This target hook need only be defined if @code{ELIMINABLE_REGS}\n\
+is defined, and will usually be @code{true}, since most of the cases\n\
+preventing register elimination are things that the compiler already\n\
+knows about.\n\
+\n\
+Default return value is @code{true}.",
  bool, (const int from_reg, const int to_reg),
  hook_bool_const_int_const_int_true)
 
@@ -2609,7 +4642,35 @@ 
    target.  */
 DEFHOOK
 (conditional_register_usage,
- "",
+ "This hook may conditionally modify five variables\n\
+@code{fixed_regs}, @code{call_used_regs}, @code{global_regs},\n\
+@code{reg_names}, and @code{reg_class_contents}, to take into account\n\
+any dependence of these register sets on target flags.  The first three\n\
+of these are of type @code{char []} (interpreted as Boolean vectors).\n\
+@code{global_regs} is a @code{const char *[]}, and\n\
+@code{reg_class_contents} is a @code{HARD_REG_SET}.  Before the macro is\n\
+called, @code{fixed_regs}, @code{call_used_regs},\n\
+@code{reg_class_contents}, and @code{reg_names} have been initialized\n\
+from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS},\n\
+@code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively.\n\
+@code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}},\n\
+@option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}\n\
+command options have been applied.\n\
+\n\
+@cindex disabling certain registers\n\
+@cindex controlling register usage\n\
+If the usage of an entire class of registers depends on the target\n\
+flags, you may indicate this to GCC by using this macro to modify\n\
+@code{fixed_regs} and @code{call_used_regs} to 1 for each of the\n\
+registers in the classes which should not be used by GCC@.  Also define\n\
+the macro @code{REG_CLASS_FROM_LETTER} / @code{REG_CLASS_FROM_CONSTRAINT}\n\
+to return @code{NO_REGS} if it\n\
+is called with a letter for a class that shouldn't be used.\n\
+\n\
+(However, if this class is not included in @code{GENERAL_REGS} and all\n\
+of the insn patterns whose constraints permit this class are\n\
+controlled by target switches, then GCC will automatically avoid using\n\
+these registers when the target switches are opposed to them.)",
  void, (void),
  hook_void_void)
 
@@ -2636,28 +4697,37 @@ 
 /* Return the integer type used for guard variables.  */
 DEFHOOK
 (guard_type,
- "",
+ "Define this hook to override the integer type used for guard variables.\n\
+These are used to implement one-time construction of static objects.  The\n\
+default is long_long_integer_type_node.",
  tree, (void),
  default_cxx_guard_type)
 
 /* Return true if only the low bit of the guard should be tested.  */
 DEFHOOK
 (guard_mask_bit,
- "",
+ "This hook determines how guard variables are used.  It should return\n\
+@code{false} (the default) if the first byte should be used.  A return value of\n\
+@code{true} indicates that only the least significant bit should be used.",
  bool, (void),
  hook_bool_void_false)
 
 /* Returns the size of the array cookie for an array of type.  */
 DEFHOOK
 (get_cookie_size,
- "",
+ "This hook returns the size of the cookie to use when allocating an array\n\
+whose elements have the indicated @var{type}.  Assumes that it is already\n\
+known that a cookie is needed.  The default is\n\
+@code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the\n\
+IA64/Generic C++ ABI@.",
  tree, (tree type),
  default_cxx_get_cookie_size)
 
 /* Returns true if the element size should be stored in the array cookie.  */
 DEFHOOK
 (cookie_has_size,
- "",
+ "This hook should return @code{true} if the element size should be stored in\n\
+array cookies.  The default is to return @code{false}.",
  bool, (void),
  hook_bool_void_false)
 
@@ -2665,13 +4735,20 @@ 
    deciding if a class should be exported or imported.  */
 DEFHOOK
 (import_export_class,
- "",
+ "If defined by a backend this hook allows the decision made to export\n\
+class @var{type} to be overruled.  Upon entry @var{import_export}\n\
+will contain 1 if the class is going to be exported, @minus{}1 if it is going\n\
+to be imported and 0 otherwise.  This function should return the\n\
+modified value and perform any other actions necessary to support the\n\
+backend's targeted operating system.",
  int, (tree type, int import_export), NULL)
 
 /* Returns true if constructors and destructors return "this".  */
 DEFHOOK
 (cdtor_returns_this,
- "",
+ "This hook should return @code{true} if constructors and destructors return\n\
+the address of the object created/destroyed.  The default is to return\n\
+@code{false}.",
  bool, (void),
  hook_bool_void_false)
 
@@ -2680,7 +4757,13 @@ 
    itself.  Returning true is the behavior required by the Itanium C++ ABI.  */
 DEFHOOK
 (key_method_may_be_inline,
- "",
+ "This hook returns true if the key method for a class (i.e., the method\n\
+which, if defined in the current translation unit, causes the virtual\n\
+table to be emitted) may be an inline function.  Under the standard\n\
+Itanium C++ ABI the key method may be an inline function so long as\n\
+the function is not declared inline in the class definition.  Under\n\
+some variants of the ABI, an inline function can never be the key\n\
+method.  The default is to return @code{true}.",
  bool, (void),
  hook_bool_void_true)
 
@@ -2702,7 +4785,11 @@ 
    only one translation unit will not be COMDAT.  */
 DEFHOOK
 (class_data_always_comdat,
- "",
+ "This hook returns true (the default) if virtual tables and other\n\
+similar implicit class data objects are always COMDAT if they have\n\
+external linkage.  If this hook returns false, then class data for\n\
+classes whose virtual table will be emitted in only one translation\n\
+unit will not be COMDAT.",
  bool, (void),
  hook_bool_void_true)
 
@@ -2711,7 +4798,9 @@ 
    false if it should not be COMDAT.  */
 DEFHOOK
 (library_rtti_comdat,
- "",
+ "This hook returns true (the default) if the RTTI information for\n\
+the basic types which is defined in the C++ runtime should always\n\
+be COMDAT, false if it should not be COMDAT.",
  bool, (void),
  hook_bool_void_true)
 
@@ -2719,7 +4808,9 @@ 
    destructors.  */
 DEFHOOK
 (use_aeabi_atexit,
- "",
+ "This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI)\n\
+should be used to register static destructors when @option{-fuse-cxa-atexit}\n\
+is in effect.  The default is to return false to use @code{__cxa_atexit}.",
  bool, (void),
  hook_bool_void_false)
 
@@ -2727,7 +4818,11 @@ 
    __cxa_atexit  to register static destructors.  */
 DEFHOOK
 (use_atexit_for_cxa_atexit,
- "",
+ "This hook returns true if the target @code{atexit} function can be used\n\
+in the same manner as @code{__cxa_atexit} to register C++ static\n\
+destructors. This requires that @code{atexit}-registered functions in\n\
+shared libraries are run in the correct order when the libraries are\n\
+unloaded. The default is to return false.",
  bool, (void),
  hook_bool_void_false)
 
@@ -2755,47 +4850,66 @@ 
 /* Name of the address and common functions.  */
 DEFHOOKPOD
 (get_address,
- "",
+ "Contains the name of the helper function that uses a TLS control\n\
+object to locate a TLS instance.  The default causes libgcc's\n\
+emulated TLS helper function to be used.",
  const char *, "__builtin___emutls_get_address")
 
 DEFHOOKPOD
 (register_common,
- "",
+ "Contains the name of the helper function that should be used at\n\
+program startup to register TLS objects that are implicitly\n\
+initialized to zero.  If this is @code{NULL}, all TLS objects will\n\
+have explicit initializers.  The default causes libgcc's emulated TLS\n\
+registration function to be used.",
  const char *, "__builtin___emutls_register_common")
 
 /* Prefixes for proxy variable and template.  */
 DEFHOOKPOD
 (var_section,
- "",
+ "Contains the name of the section in which TLS control variables should\n\
+be placed.  The default of @code{NULL} allows these to be placed in\n\
+any section.",
  const char *, NULL)
 
 DEFHOOKPOD
 (tmpl_section,
- "",
+ "Contains the name of the section in which TLS initializers should be\n\
+placed.  The default of @code{NULL} allows these to be placed in any\n\
+section.",
  const char *, NULL)
 
 /* Prefixes for proxy variable and template.  */
 DEFHOOKPOD
 (var_prefix,
- "",
+ "Contains the prefix to be prepended to TLS control variable names.\n\
+The default of @code{NULL} uses a target-specific prefix.",
  const char *, NULL)
 
 DEFHOOKPOD
 (tmpl_prefix,
- "",
+ "Contains the prefix to be prepended to TLS initializer objects.  The\n\
+default of @code{NULL} uses a target-specific prefix.",
  const char *, NULL)
 
 /* Function to generate field definitions of the proxy variable.  */
 DEFHOOK
 (var_fields,
- "",
+ "Specifies a function that generates the FIELD_DECLs for a TLS control\n\
+object type.  @var{type} is the RECORD_TYPE the fields are for and\n\
+@var{name} should be filled with the structure tag, if the default of\n\
+@code{__emutls_object} is unsuitable.  The default creates a type suitable\n\
+for libgcc's emulated TLS function.",
  tree, (tree type, tree *name),
  default_emutls_var_fields)
 
 /* Function to initialize a proxy variable.  */
 DEFHOOK
 (var_init,
- "",
+ "Specifies a function that generates the CONSTRUCTOR to initialize a\n\
+TLS control object.  @var{var} is the TLS control object, @var{decl}\n\
+is the TLS object and @var{tmpl_addr} is the address of the\n\
+initializer.  The default initializes libgcc's emulated TLS control object.",
  tree, (tree var, tree decl, tree tmpl_addr),
  default_emutls_var_init)
 
@@ -2803,13 +4917,16 @@ 
    proxy variable.  */
 DEFHOOKPOD
 (var_align_fixed,
- "",
+ "Specifies whether the alignment of TLS control variable objects is\n\
+fixed and should not be increased as some backends may do to optimize\n\
+single objects.  The default is false.",
  bool, false)
 
 /* Whether we can emit debug information for TLS vars.  */
 DEFHOOKPOD
 (debug_form_tls_address,
- "",
+ "Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor\n\
+may be used to describe emulated TLS control objects.",
  bool, false)
 
 HOOK_VECTOR_END (emutls)
@@ -2823,28 +4940,43 @@ 
    DECL_FUNCTION_SPECIFIC_TARGET in the function decl node.  */
 DEFHOOK
 (valid_attribute_p,
- "",
+ "This hook is called to parse @code{attribute(target(\"...\"))}, which\n\
+allows setting target-specific options on individual functions.\n\
+These function-specific options may differ\n\
+from the options specified on the command line.  The hook should return\n\
+@code{true} if the options are valid.\n\
+\n\
+The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
+the function declaration to hold a pointer to a target-specific\n\
+@code{struct cl_target_option} structure.",
  bool, (tree fndecl, tree name, tree args, int flags),
  default_target_option_valid_attribute_p)
 
 /* Function to save any extra target state in the target options structure.  */
 DEFHOOK
 (save,
- "",
+ "This hook is called to save any additional target-specific information\n\
+in the @code{struct cl_target_option} structure for function-specific\n\
+options.\n\
+@xref{Option file format}.",
  void, (struct cl_target_option *ptr), NULL)
 
 /* Function to restore any extra target state from the target options
    structure.  */
 DEFHOOK
 (restore,
- "",
+ "This hook is called to restore any additional target-specific\n\
+information in the @code{struct cl_target_option} structure for\n\
+function-specific options.",
  void, (struct cl_target_option *ptr), NULL)
 
 /* Function to print any extra target state from the target options
    structure.  */
 DEFHOOK
 (print,
- "",
+ "This hook is called to print any additional target-specific\n\
+information in the @code{struct cl_target_option} structure for\n\
+function-specific options.",
  void, (FILE *file, int indent, struct cl_target_option *ptr), NULL)
 
 /* Function to parse arguments to be validated for #pragma target, and to
@@ -2853,14 +4985,27 @@ 
    true if the options are valid, and set the current state.  */
 DEFHOOK
 (pragma_parse,
- "",
+ "This target hook parses the options for @code{#pragma GCC target}, which\n\
+sets the target-specific options for functions that occur later in the\n\
+input stream.  The options accepted should be the same as those handled by the\n\
+@code{TARGET_OPTION_VALID_ATTRIBUTE_P} hook.",
  bool, (tree args, tree pop_target),
  default_target_option_pragma_parse)
 
 /* Do option overrides for the target.  */
 DEFHOOK
 (override,
- "",
+ "Sometimes certain combinations of command options do not make sense on\n\
+a particular target machine.  You can override the hook\n\
+@code{TARGET_OPTION_OVERRIDE} to take account of this.  This hooks is called\n\
+once just after all the command options have been parsed.\n\
+\n\
+Don't use this hook to turn on various extra optimizations for\n\
+@option{-O}.  That is what @code{TARGET_OPTION_OPTIMIZATION} is for.\n\
+\n\
+If you need to do something whenever the optimization level is\n\
+changed via the optimize attribute or pragma, see\n\
+@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}",
  void, (void),
  hook_void_void)
 
@@ -2870,7 +5015,11 @@ 
    that is, they are compiled for different target machines.  */
 DEFHOOK
 (function_versions,
- "",
+ "This target hook returns @code{true} if @var{DECL1} and @var{DECL2} are\n\
+versions of the same function.  @var{DECL1} and @var{DECL2} are function\n\
+versions if and only if they have the same function signature and\n\
+different target specific attributes, that is, they are compiled for\n\
+different target machines.",
  bool, (tree decl1, tree decl2),
  hook_bool_tree_tree_false)
 
@@ -2879,7 +5028,10 @@ 
 #define HOOK_PREFIX "TARGET_"
 DEFHOOK
 (can_inline_p,
- "",
+ "This target hook returns @code{false} if the @var{caller} function\n\
+cannot inline @var{callee}, based on target specific information.  By\n\
+default, inlining is not allowed if the callee function has function\n\
+specific target options and the caller does not use the same options.",
  bool, (tree caller, tree callee),
  default_target_can_inline_p)
 
@@ -2890,7 +5042,12 @@ 
    bits in the bitmap passed in. */
 DEFHOOK
 (extra_live_on_entry,
- "",
+ "Add any hard registers to @var{regs} that are live on entry to the\n\
+function.  This hook only needs to be defined to provide registers that\n\
+cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved\n\
+registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,\n\
+TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,\n\
+FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.",
  void, (bitmap regs),
  hook_void_bitmap)
 
@@ -2914,7 +5071,16 @@ 
 /* Determine the type of unwind info to emit for debugging.  */
 DEFHOOK
 (debug_unwind_info,
- "",
+ "This hook defines the mechanism that will be used for describing frame\n\
+unwind information to the debugger.  Normally the hook will return\n\
+@code{UI_DWARF2} if DWARF 2 debug information is enabled, and\n\
+return @code{UI_NONE} otherwise.\n\
+\n\
+A target may return @code{UI_DWARF2} even when DWARF 2 debug information\n\
+is disabled in order to always output DWARF 2 frame information.\n\
+\n\
+A target may return @code{UI_TARGET} if it has ABI specified unwind tables.\n\
+This will suppress generation of the normal debug frame unwind information.",
  enum unwind_info_type, (void),
  default_debug_unwind_info)
 
@@ -2922,7 +5088,25 @@ 
    defined at this time.  */
 DEFHOOK
 (canonicalize_comparison,
- "",
+ "On some machines not all possible comparisons are defined, but you can\n\
+convert an invalid comparison into a valid one.  For example, the Alpha\n\
+does not have a @code{GT} comparison, but you can use an @code{LT}\n\
+comparison instead and swap the order of the operands.\n\
+\n\
+On such machines, implement this hook to do any required conversions.\n\
+@var{code} is the initial comparison code and @var{op0} and @var{op1}\n\
+are the left and right operands of the comparison, respectively.  If\n\
+@var{op0_preserve_value} is @code{true} the implementation is not\n\
+allowed to change the value of @var{op0} since the value might be used\n\
+in RTXs which aren't comparisons.  E.g. the implementation is not\n\
+allowed to swap operands in that case.\n\
+\n\
+GCC will not assume that the comparison resulting from this macro is\n\
+valid but will see if the resulting insn matches a pattern in the\n\
+@file{md} file.\n\
+\n\
+You need not to implement this hook if it would never change the\n\
+comparison code or operands.",
  void, (int *code, rtx *op0, rtx *op1, bool op0_preserve_value),
  default_canonicalize_comparison)
 
@@ -2939,59 +5123,90 @@ 
    and then using ASM_OUTPUT_SKIP to allocate the space.  */
 DEFHOOKPOD
 (have_switchable_bss_sections,
- "",
+ "This flag is true if we can create zeroed data by switching to a BSS\n\
+section and then using @code{ASM_OUTPUT_SKIP} to allocate the space.\n\
+This is true on most ELF targets.",
  bool, false)
 
 /* True if "native" constructors and destructors are supported,
    false if we're using collect2 for the job.  */
 DEFHOOKPOD
 (have_ctors_dtors,
- "",
+ "This value is true if the target supports some ``native'' method of\n\
+collecting constructors and destructors to be run at startup and exit.\n\
+It is false if we must use @command{collect2}.",
  bool, false)
 
 /* True if thread-local storage is supported.  */
 DEFHOOKPOD
 (have_tls,
- "",
+ "Contains the value true if the target supports thread-local storage.\n\
+The default value is false.",
  bool, false)
 
 /* True if a small readonly data section is supported.  */
 DEFHOOKPOD
 (have_srodata_section,
- "",
+ "Contains the value true if the target places read-only\n\
+``small data'' into a separate section.  The default value is false.",
  bool, false)
 
 /* True if EH frame info sections should be zero-terminated.  */
 DEFHOOKPOD
 (terminate_dw2_eh_frame_info,
- "",
+ "Contains the value true if the target should add a zero word onto the\n\
+end of a Dwarf-2 frame info section when used for exception handling.\n\
+Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and\n\
+true otherwise.",
  bool, true)
 
 /* True if #NO_APP should be emitted at the beginning of assembly output.  */
 DEFHOOKPOD
 (asm_file_start_app_off,
- "",
+ "If this flag is true, the text of the macro @code{ASM_APP_OFF} will be\n\
+printed as the very first line in the assembly file, unless\n\
+@option{-fverbose-asm} is in effect.  (If that macro has been defined\n\
+to the empty string, this variable has no effect.)  With the normal\n\
+definition of @code{ASM_APP_OFF}, the effect is to notify the GNU\n\
+assembler that it need not bother stripping comments or extra\n\
+whitespace from its input.  This allows it to work a bit faster.\n\
+\n\
+The default is false.  You should not set it to true unless you have\n\
+verified that your port does not generate any extra whitespace or\n\
+comments that will cause GAS to issue errors in NO_APP mode.",
  bool, false)
 
 /* True if output_file_directive should be called for main_input_filename
    at the beginning of assembly output.  */
 DEFHOOKPOD
 (asm_file_start_file_directive,
- "",
+ "If this flag is true, @code{output_file_directive} will be called\n\
+for the primary source file, immediately after printing\n\
+@code{ASM_APP_OFF} (if that is enabled).  Most ELF assemblers expect\n\
+this to be done.  The default is false.",
  bool, false)
 
 /* True if the target is allowed to reorder memory accesses unless
    synchronization is explicitly requested.  */
 DEFHOOKPOD
 (relaxed_ordering,
- "",
+ "If set to @code{true}, means that the target's memory model does not\n\
+guarantee that loads which do not depend on one another will access\n\
+main memory in the order of the instruction stream; if ordering is\n\
+important, an explicit memory barrier must be used.  This is true of\n\
+many recent processors which implement a policy of ``relaxed,''\n\
+``weak,'' or ``release'' memory consistency, such as Alpha, PowerPC,\n\
+and ia64.  The default is @code{false}.",
  bool, false)
 
 /* Returns true if we should generate exception tables for use with the
    ARM EABI.  The effects the encoding of function exception specifications.  */
 DEFHOOKPOD
 (arm_eabi_unwinder,
- "",
+ "This flag should be set to @code{true} on targets that use an ARM EABI\n\
+based unwinding library, and @code{false} on other targets.  This effects\n\
+the format of unwinding tables, and how the unwinder in entered after\n\
+running a cleanup.  The default is @code{false}.",
  bool, false)
 
 DEFHOOKPOD