, PowerPC IEEE 128-bit patch #7 (revised)

This is a revised patch that adds the parts to enable generation of IEEE
128-bit floating point support in the PowerPC backend.

The major user visible change of this patch is to change the switch from
-mfloat128-software and -mfloat128-none to just -mfloat128 and -mno-float128.
I also revised some of the support functions in rs6000.c to work better with
future patches.

In working on the future patches, I also noticed that I had allowed the
conversion routines to support target being a memory address (via the
nonimmediate_operand predicate), and I restricted it to register.

The next patch will be to libgcc to enable building the emulation routines, so
that you can use IEEE 128-bit floating point. It is expected that initially
these patches will be a temporary measure until the glibc team takes ownership
of the emulation functions (the soft-fp directory of libgcc comes from glibc).

Once the libgcc routines are in place, I will then submit a patch to flip the
default, so that enabling VSX options will enable -mfloat128 by default.

I expect there to be various additional patches as things come up as well.  Of
the top of my head, I will probably be adding built-in functions for sqrt and
abs.  I also want to tackle making _Complex __float128 work without having to
use attributes.

The patch has been bootstrapped on a Power7 big endian system and a Power8
little endian system with no regressions. I also built compilers with/without
the changes targetting power5 as a default and there were no regressions there
either.  Are these patches ok to install on the trunk?

[gcc]
2015-09-14  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/rs6000-cpus.h (POWERPC_MASKS): Add -mfloat128.

	* config/rs6000/rs6000-c.c (rs6000_cpu_cpp_builtins): Define new
	macros to identify if __float128 is available, and whether long
	double is IBM extended double or IEEE 128-bit floating point.

	* config/rs6000/rs6000.opt (-mfloat128): Change IEEE 128-bit
	switches from -mfloat128-none and -mfloat128-software to
	-mfloat128 and -mno-float128.
	(-mfloat128-): Delete.
	(float128_type_t): Delete.

	* config/rs6000/rs6000.c (rs6000_c_mode_for_suffix): Define 'q'
	and 'Q' as the suffixes for __float128 constants.
	(TARGET_C_MODE_FOR_SUFFIX): Likewise.
	(rs6000_hard_regno_mode_ok): Remove tests disallowing IEEE 128-bit
	floating point modes from GPRs if not -mfloat128.
	(rs6000_debug_reg_global): Delete debug support for
	-mfloat128-software and -mfloat128-none.
	(rs6000_setup_reg_addr_masks): IEEE 128-bit in floating point is
	not suitable for auto increment or decrement.
	(rs6000_init_hard_regno_mode_ok): Enable VSX constraints and
	addressing for IEEE 128-bit floating point in VSX registers.
	(rs6000_option_override_internal): Update test for __float128
	support.
	(rs6000_gen_le_vsx_permute): Add support for -mfloat128.
	(init_cumulative_args): Likewise.
	(rs6000_function_arg): Likewise.
	(rs6000_arg_partial_bytes): Likewise.
	(rs6000_init_builtins): Rework __float128 support.
	(init_float128_ibm): Add __float128 support. Split support into
	separate functions for IEEE 128-bit floating point and IBM
	extended double support.
	(init_float128_ieee): Likewise.
	(rs6000_init_libfuncs): Likewise.
	(rs6000_expand_float128_convert): Use switch statements to handle
	different types.
	(rs6000_mangle_type): Add __float128 mangling support.
	(rs6000_scalar_mode_supported_p): Rework __float128 support.
	(rs6000_opt_masks): Add -mfloat128 support.
	(chain_contains_only_swaps): Use ALTIVEC_OR_VSX_VECTOR_MODE
	instead of VECTOR_MODE_P in order to treat IEEE1 28-bit floating
	point in VSX registers like vector types, and treat it like a
	128-bit integer.
	(mark_swaps_for_removal): Likewise.
	(rs6000_analyze_swaps): Likewise.

	* config/rs6000/rs6000.h (ALTIVEC_VECTOR_MODE): Include __float128
	modes as 'vector' modes.
	(MODES_TIEABLE_P): Move checking for vector modes above scalar
	floating point, so that __float128 types tie with vector types.
	(struct rs6000_args): Add libcall field for __float128 support
	functions.

	* config/rs6000/rs6000.md (extend<FLOAT128_SFDFTF:mode><IFKF:mode>2):
	Require target to be a register, not a memory operand.
	(trunk<FLOAT128_SFDFTF:mode><IFKF:mode>2): Likewise.

	* config/rs6000/rs6000-opts.h (enum float128_type_t): Delete,
	switch to -mfloat128 and -mno-float128 from -mfloat128-software
	and -mfloat128-none.

	* doc/extend.texi (additional floating types): Document PowerPC
	use of __float128 and __ibm128 types.

	* doc/invoke.texi (RS/6000 and PowerPC Options): Document
	-mfloat128 and -mno-float128.

[gcc/testsuite]
2015-09-14  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/float128-call.c: New function, test whether
	IEEE 128-bit floating point in VSX registers is passed correctly.

, PowerPC IEEE 128-bit patch #7 (revised)

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