From 1c95f904681552744ac08f00d782942674d8ede2 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Sun, 6 Aug 2017 06:24:36 -0700 Subject: i386: Don't use frame pointer without stack access When there is no stack access, there is no need to use frame pointer even if -fno-omit-frame-pointer is used and caller's frame pointer is unchanged. gcc/ PR target/81736 * config/i386/i386.c (ix86_finalize_stack_realign_flags): Renamed to ... (ix86_finalize_stack_frame_flags): This. Also clear frame_pointer_needed if -fno-omit-frame-pointer is used without stack access. (ix86_expand_prologue): Replace ix86_finalize_stack_realign_flags with ix86_finalize_stack_frame_flags. (ix86_expand_epilogue): Likewise. (ix86_expand_split_stack_prologue): Likewise. * doc/invoke.texi: Add a note for -fno-omit-frame-pointer. gcc/testsuite/ PR target/81736 * gcc.target/i386/pr81736-1.c: New test. * gcc.target/i386/pr81736-2.c: Likewise. * gcc.target/i386/pr81736-3.c: Likewise. * gcc.target/i386/pr81736-4.c: Likewise. * gcc.target/i386/pr81736-5.c: Likewise. * gcc.target/i386/pr81736-6.c: Likewise. * gcc.target/i386/pr81736-7.c: Likewise. (cherry picked from commit cd557ff63f388ad27c376d0a225e74d3594a6f9d) --- gcc/config/i386/i386.c | 23 ++++++++++++----------- gcc/doc/invoke.texi | 4 ++++ gcc/testsuite/gcc.target/i386/pr81736-1.c | 13 +++++++++++++ gcc/testsuite/gcc.target/i386/pr81736-2.c | 14 ++++++++++++++ gcc/testsuite/gcc.target/i386/pr81736-3.c | 11 +++++++++++ gcc/testsuite/gcc.target/i386/pr81736-4.c | 11 +++++++++++ gcc/testsuite/gcc.target/i386/pr81736-5.c | 20 ++++++++++++++++++++ gcc/testsuite/gcc.target/i386/pr81736-6.c | 16 ++++++++++++++++ gcc/testsuite/gcc.target/i386/pr81736-7.c | 13 +++++++++++++ 9 files changed, 114 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-1.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-2.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-3.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-4.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-5.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-6.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81736-7.c diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 2d163797ba0..9c1e17eeaa1 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -13581,10 +13581,11 @@ output_probe_stack_range (rtx reg, rtx end) return ""; } -/* Finalize stack_realign_needed flag, which will guide prologue/epilogue - to be generated in correct form. */ +/* Finalize stack_realign_needed and frame_pointer_needed flags, which + will guide prologue/epilogue to be generated in correct form. */ + static void -ix86_finalize_stack_realign_flags (void) +ix86_finalize_stack_frame_flags (void) { /* Check if stack realign is really needed after reload, and stores result in cfun */ @@ -13606,13 +13607,13 @@ ix86_finalize_stack_realign_flags (void) } /* If the only reason for frame_pointer_needed is that we conservatively - assumed stack realignment might be needed, but in the end nothing that - needed the stack alignment had been spilled, clear frame_pointer_needed - and say we don't need stack realignment. */ - if (stack_realign + assumed stack realignment might be needed or -fno-omit-frame-pointer + is used, but in the end nothing that needed the stack alignment had + been spilled nor stack access, clear frame_pointer_needed and say we + don't need stack realignment. */ + if ((stack_realign || !flag_omit_frame_pointer) && frame_pointer_needed && crtl->is_leaf - && flag_omit_frame_pointer && crtl->sp_is_unchanging && !ix86_current_function_calls_tls_descriptor && !crtl->accesses_prior_frames @@ -13719,7 +13720,7 @@ ix86_expand_prologue (void) bool sse_registers_saved; rtx static_chain = NULL_RTX; - ix86_finalize_stack_realign_flags (); + ix86_finalize_stack_frame_flags (); /* DRAP should not coexist with stack_realign_fp */ gcc_assert (!(crtl->drap_reg && stack_realign_fp)); @@ -14403,7 +14404,7 @@ ix86_expand_epilogue (int style) bool restore_regs_via_mov; bool using_drap; - ix86_finalize_stack_realign_flags (); + ix86_finalize_stack_frame_flags (); ix86_compute_frame_layout (&frame); m->fs.sp_valid = (!frame_pointer_needed @@ -14913,7 +14914,7 @@ ix86_expand_split_stack_prologue (void) gcc_assert (flag_split_stack && reload_completed); - ix86_finalize_stack_realign_flags (); + ix86_finalize_stack_frame_flags (); ix86_compute_frame_layout (&frame); allocate = frame.stack_pointer_offset - INCOMING_FRAME_SP_OFFSET; diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index a0fb09eb9e1..215b2ef177b 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -7223,6 +7223,10 @@ size) for 32-bit GNU/Linux x86 and 32-bit Darwin x86 targets is @option{-fomit-frame-pointer}. You can configure GCC with the @option{--enable-frame-pointer} configure option to change the default. +Note that @option{-fno-omit-frame-pointer} doesn't force a new stack +frame for all functions if it isn't otherwise needed, and hence doesn't +guarantee a new frame pointer for all functions. + Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}. @item -foptimize-sibling-calls diff --git a/gcc/testsuite/gcc.target/i386/pr81736-1.c b/gcc/testsuite/gcc.target/i386/pr81736-1.c new file mode 100644 index 00000000000..92c7bc97a0d --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-1.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +extern int i; + +int +foo (void) +{ + return i; +} + +/* No need to use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-2.c b/gcc/testsuite/gcc.target/i386/pr81736-2.c new file mode 100644 index 00000000000..a3720879937 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-2.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +int +#ifndef __x86_64__ +__attribute__((regparm(3))) +#endif +foo (int i) +{ + return i; +} + +/* No need to use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-3.c b/gcc/testsuite/gcc.target/i386/pr81736-3.c new file mode 100644 index 00000000000..c3bde7dd933 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-3.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +void +foo (void) +{ + asm ("# " : : : "ebx"); +} + +/* Need to use a frame pointer. */ +/* { dg-final { scan-assembler "%\[re\]bp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-4.c b/gcc/testsuite/gcc.target/i386/pr81736-4.c new file mode 100644 index 00000000000..25f50016a64 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-4.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +int +foo (int i1, int i2, int i3, int i4, int i5, int i6, int i7) +{ + return i7; +} + +/* Need to use a frame pointer. */ +/* { dg-final { scan-assembler "%\[re\]bp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-5.c b/gcc/testsuite/gcc.target/i386/pr81736-5.c new file mode 100644 index 00000000000..e1602cf25ba --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-5.c @@ -0,0 +1,20 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer -mavx" } */ + +typedef int v8si __attribute__ ((vector_size (32))); + +void +#ifndef __x86_64__ +__attribute__((regparm(3))) +#endif +foo (v8si *out_start, v8si *out_end, v8si *regions) +{ + v8si base = regions[3]; + *out_start = base; + *out_end = base; +} + +/* No need to use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ +/* Verify no dynamic realignment is performed. */ +/* { dg-final { scan-assembler-not "and\[^\n\r]*sp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-6.c b/gcc/testsuite/gcc.target/i386/pr81736-6.c new file mode 100644 index 00000000000..6198574c8cc --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-6.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +struct foo +{ + int head; +} a; + +int +bar (void) +{ + return a.head != 0; +} + +/* No need to use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81736-7.c b/gcc/testsuite/gcc.target/i386/pr81736-7.c new file mode 100644 index 00000000000..f947886e642 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81736-7.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-omit-frame-pointer" } */ + +extern int foo (void); + +int +bar (void) +{ + return foo (); +} + +/* No need to use a frame pointer. */ +/* { dg-final { scan-assembler-not "%\[re\]bp" } } */ -- cgit v1.2.1