| Message ID | 20200205143300.144541-3-hjl.tools@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Update -fpatchable-function-entry implementation | expand |
"H.J. Lu" <hjl.tools@gmail.com> writes: > Currently patchable area is at the wrong place. Agreed :-) > It is placed immediately > after function label and before .cfi_startproc. A backend should be able > to add a pseudo patchable area instruction durectly into RTL. This patch > adds patch_area_size and patch_area_entry to cfun so that the patchable > area info is available in RTL passes. It might be better to add it to crtl, since it should only be needed during rtl generation. > It also limits patch_area_size and patch_area_entry to 65535, which is > a reasonable maximum size for patchable area. > > gcc/ > > PR target/93492 > * function.c (expand_function_start): Set cfun->patch_area_size > and cfun->patch_area_entry. > * function.h (function): Add patch_area_size and patch_area_entry. > * opts.c (common_handle_option): Limit > function_entry_patch_area_size and function_entry_patch_area_start > to USHRT_MAX. Fix a typo in error message. > * varasm.c (assemble_start_function): Use cfun->patch_area_size > and cfun->patch_area_entry. > * doc/invoke.texi: Document the maximum value for > -fpatchable-function-entry. > > gcc/testsuite/ > > PR target/93492 > * c-c++-common/patchable_function_entry-error-1.c: New test. > * c-c++-common/patchable_function_entry-error-2.c: Likewise. > * c-c++-common/patchable_function_entry-error-3.c: Likewise. > --- > gcc/doc/invoke.texi | 1 + > gcc/function.c | 35 +++++++++++++++++++ > gcc/function.h | 6 ++++ > gcc/opts.c | 4 ++- > .../patchable_function_entry-error-1.c | 9 +++++ > .../patchable_function_entry-error-2.c | 9 +++++ > .../patchable_function_entry-error-3.c | 20 +++++++++++ > gcc/varasm.c | 30 ++-------------- > 8 files changed, 85 insertions(+), 29 deletions(-) > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index 35b341e759f..dd4835199b0 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -13966,6 +13966,7 @@ If @code{N=0}, no pad location is recorded. > The NOP instructions are inserted at---and maybe before, depending on > @var{M}---the function entry address, even before the prologue. > > +The maximum value of @var{N} and @var{M} is 65535. > @end table > > > diff --git a/gcc/function.c b/gcc/function.c > index d8008f60422..badbf538eec 100644 > --- a/gcc/function.c > +++ b/gcc/function.c > @@ -5202,6 +5202,41 @@ expand_function_start (tree subr) > /* If we are doing generic stack checking, the probe should go here. */ > if (flag_stack_check == GENERIC_STACK_CHECK) > stack_check_probe_note = emit_note (NOTE_INSN_DELETED); > + > + unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size; > + unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start; > + > + tree patchable_function_entry_attr > + = lookup_attribute ("patchable_function_entry", > + DECL_ATTRIBUTES (cfun->decl)); > + if (patchable_function_entry_attr) > + { > + tree pp_val = TREE_VALUE (patchable_function_entry_attr); > + tree patchable_function_entry_value1 = TREE_VALUE (pp_val); > + > + patch_area_size = tree_to_uhwi (patchable_function_entry_value1); > + patch_area_entry = 0; > + if (TREE_CHAIN (pp_val) != NULL_TREE) > + { > + tree patchable_function_entry_value2 > + = TREE_VALUE (TREE_CHAIN (pp_val)); > + patch_area_entry = tree_to_uhwi (patchable_function_entry_value2); > + } > + if (patch_area_size > USHRT_MAX || patch_area_size > USHRT_MAX) > + error ("invalid values for %<patchable_function_entry%> attribute"); This should probably go in handle_patchable_function_entry_attribute instead. It doesn't look like we have a clear policy about whether errors or warnings are right for unrecognised arguments to known attribute names, but handle_patchable_function_entry_attribute reports an OPT_Wattributes warning for arguments that aren't integers. Doing the same for out-of-range integers would be more consistent and means that we wouldn't break existing code if we relaxed/changed the rules in future. Thanks, Richard
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 35b341e759f..dd4835199b0 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -13966,6 +13966,7 @@ If @code{N=0}, no pad location is recorded. The NOP instructions are inserted at---and maybe before, depending on @var{M}---the function entry address, even before the prologue. +The maximum value of @var{N} and @var{M} is 65535. @end table diff --git a/gcc/function.c b/gcc/function.c index d8008f60422..badbf538eec 100644 --- a/gcc/function.c +++ b/gcc/function.c @@ -5202,6 +5202,41 @@ expand_function_start (tree subr) /* If we are doing generic stack checking, the probe should go here. */ if (flag_stack_check == GENERIC_STACK_CHECK) stack_check_probe_note = emit_note (NOTE_INSN_DELETED); + + unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size; + unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start; + + tree patchable_function_entry_attr + = lookup_attribute ("patchable_function_entry", + DECL_ATTRIBUTES (cfun->decl)); + if (patchable_function_entry_attr) + { + tree pp_val = TREE_VALUE (patchable_function_entry_attr); + tree patchable_function_entry_value1 = TREE_VALUE (pp_val); + + patch_area_size = tree_to_uhwi (patchable_function_entry_value1); + patch_area_entry = 0; + if (TREE_CHAIN (pp_val) != NULL_TREE) + { + tree patchable_function_entry_value2 + = TREE_VALUE (TREE_CHAIN (pp_val)); + patch_area_entry = tree_to_uhwi (patchable_function_entry_value2); + } + if (patch_area_size > USHRT_MAX || patch_area_size > USHRT_MAX) + error ("invalid values for %<patchable_function_entry%> attribute"); + } + + if (patch_area_entry > patch_area_size) + { + if (patch_area_size > 0) + warning (OPT_Wattributes, + "patchable function entry %wu exceeds size %wu", + patch_area_entry, patch_area_size); + patch_area_entry = 0; + } + + cfun->patch_area_size = patch_area_size; + cfun->patch_area_entry = patch_area_entry; } void diff --git a/gcc/function.h b/gcc/function.h index 1ee8ed3de53..1ed7c400f23 100644 --- a/gcc/function.h +++ b/gcc/function.h @@ -332,6 +332,12 @@ struct GTY(()) function { /* Last assigned dependence info clique. */ unsigned short last_clique; + /* How many NOP insns to place at each function entry by default. */ + unsigned short patch_area_size; + + /* How far the real asm entry point is into this area. */ + unsigned short patch_area_entry; + /* Collected bit flags. */ /* Number of units of general registers that need saving in stdarg diff --git a/gcc/opts.c b/gcc/opts.c index 7affeb41a96..c6011f1f9b7 100644 --- a/gcc/opts.c +++ b/gcc/opts.c @@ -2598,10 +2598,12 @@ common_handle_option (struct gcc_options *opts, function_entry_patch_area_start = 0; } if (function_entry_patch_area_size < 0 + || function_entry_patch_area_size > USHRT_MAX || function_entry_patch_area_start < 0 + || function_entry_patch_area_start > USHRT_MAX || function_entry_patch_area_size < function_entry_patch_area_start) - error ("invalid arguments for %<-fpatchable_function_entry%>"); + error ("invalid arguments for %<-fpatchable-function-entry%>"); free (patch_area_arg); } break; diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c new file mode 100644 index 00000000000..f60bf46cfe3 --- /dev/null +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c @@ -0,0 +1,9 @@ +/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */ +/* { dg-options "-O2 -fpatchable-function-entry=65536,1" } */ +/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */ +/* { dg-error "invalid arguments for '-fpatchable-function-entry'" "" { target *-*-* } 0 } */ + +void +foo (void) +{ +} diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c new file mode 100644 index 00000000000..90f88c78be7 --- /dev/null +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c @@ -0,0 +1,9 @@ +/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */ +/* { dg-options "-O2 -fpatchable-function-entry=1,65536" } */ +/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */ +/* { dg-error "invalid arguments for '-fpatchable-function-entry'" "" { target *-*-* } 0 } */ + +void +foo (void) +{ +} diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c new file mode 100644 index 00000000000..b6e449425d2 --- /dev/null +++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c @@ -0,0 +1,20 @@ +/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */ +/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */ + +void + __attribute__((patchable_function_entry(65536))) +foo1 (void) /* { dg-error "invalid values for 'patchable_function_entry'" } */ +{ +} + +void + __attribute__((patchable_function_entry(65536,1))) +foo2 (void) /* { dg-error "invalid values for 'patchable_function_entry'" } */ +{ +} + +void + __attribute__((patchable_function_entry(65536,65536))) +foo3 (void) /* { dg-error "invalid values for 'patchable_function_entry'" } */ +{ +} diff --git a/gcc/varasm.c b/gcc/varasm.c index dc6da6c0b5b..93251f07d6e 100644 --- a/gcc/varasm.c +++ b/gcc/varasm.c @@ -1857,34 +1857,8 @@ assemble_start_function (tree decl, const char *fnname) if (DECL_PRESERVE_P (decl)) targetm.asm_out.mark_decl_preserved (fnname); - unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size; - unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start; - - tree patchable_function_entry_attr - = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl)); - if (patchable_function_entry_attr) - { - tree pp_val = TREE_VALUE (patchable_function_entry_attr); - tree patchable_function_entry_value1 = TREE_VALUE (pp_val); - - patch_area_size = tree_to_uhwi (patchable_function_entry_value1); - patch_area_entry = 0; - if (TREE_CHAIN (pp_val) != NULL_TREE) - { - tree patchable_function_entry_value2 - = TREE_VALUE (TREE_CHAIN (pp_val)); - patch_area_entry = tree_to_uhwi (patchable_function_entry_value2); - } - } - - if (patch_area_entry > patch_area_size) - { - if (patch_area_size > 0) - warning (OPT_Wattributes, - "patchable function entry %wu exceeds size %wu", - patch_area_entry, patch_area_size); - patch_area_entry = 0; - } + unsigned short patch_area_size = cfun->patch_area_size; + unsigned short patch_area_entry = cfun->patch_area_entry; /* Emit the patching area before the entry label, if any. */ if (patch_area_entry > 0)