From patchwork Thu Jul 15 17:42:47 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: RFC: Turn on -fomit-frame-pointer and -fasynchronous-unwind-tables for Linux/i386 Date: Thu, 15 Jul 2010 07:42:47 -0000 From: "H.J. Lu" X-Patchwork-Id: 58999 Message-Id: <20100715174246.GA20583@intel.com> To: gcc-patches@gcc.gnu.org Cc: Uros Bizjak Hi, This patch turns on -fomit-frame-pointer and -fasynchronous-unwind-tables for Linux/i386. Tested on Linux/ia32 and Linux/x86-64. I am also enclosing a spreadsheet of comparison of shared library segment sizes in gcc. Segment size differences range from -1% to 30%. The smaller the DSO size is, the bigger its size increases. Overall, the size difference is close to 0%. This comparison may not be typical since C++ and Java libraries have .eh_frame sections anyway. Any comments? Thanks. H.J. --- gcc/ 2010-07-14 H.J. Lu * config/i386/i386.c (override_options): Default flag_omit_frame_pointer and flag_asynchronous_unwind_tables to TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT and TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT. * config/i386/i386.h (TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT): New. (TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT): Likewise. * config/i386/linux.h (TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT): Likewise. (TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT): Likewise. * config/i386/linux64.h (TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT): Likewise. (TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT): Likewise. gcc/testsuite/ 2010-07-15 H.J. Lu * gcc.target/i386/frame-pointer-1.c: New. * gcc.target/i386/frame-pointer-2.c: Likewise. * gcc.target/i386/frame-pointer-3.c: Likewise. * gcc.target/i386/frame-pointer-4.c: Likewise. diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 4fd2aab..fe30bfd 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -2985,10 +2985,23 @@ override_options (bool main_args_p) { if (flag_zee == 2) flag_zee = 0; + /* Unwind info is not correct around the CFG unless either a + frame pointer is present or -maccumulate-outgoing-args is + set. When both -fasynchronous-unwind-tables and + -fomit-frame-pointer are turned on by default, turn off + both if -mno-accumulate-outgoing-args is used. */ if (flag_omit_frame_pointer == 2) - flag_omit_frame_pointer = 0; + flag_omit_frame_pointer + = (TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT + && (!TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT + || !(target_flags_explicit + & MASK_ACCUMULATE_OUTGOING_ARGS))); if (flag_asynchronous_unwind_tables == 2) - flag_asynchronous_unwind_tables = 0; + flag_asynchronous_unwind_tables + = (TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT + && (!TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT + || !(target_flags_explicit + & MASK_ACCUMULATE_OUTGOING_ARGS))); if (flag_pcc_struct_return == 2) flag_pcc_struct_return = DEFAULT_PCC_STRUCT_RETURN; } diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h index eb3eb9f..c0ae95f 100644 --- a/gcc/config/i386/i386.h +++ b/gcc/config/i386/i386.h @@ -467,6 +467,8 @@ extern tree x86_mfence; /* Extra bits to force on w/ 32-bit mode. */ #define TARGET_SUBTARGET32_DEFAULT 0 #define TARGET_SUBTARGET32_ISA_DEFAULT 0 +#define TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT 0 +#define TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT 0 /* Extra bits to force on w/ 64-bit mode. */ #define TARGET_SUBTARGET64_DEFAULT 0 diff --git a/gcc/config/i386/linux.h b/gcc/config/i386/linux.h index 81dfd1e..61d53b5 100644 --- a/gcc/config/i386/linux.h +++ b/gcc/config/i386/linux.h @@ -219,3 +219,10 @@ along with GCC; see the file COPYING3. If not see /* i386 glibc provides __stack_chk_guard in %gs:0x14. */ #define TARGET_THREAD_SSP_OFFSET 0x14 #endif + +/* Turn on -fomit-frame-pointer and -fasynchronous-unwind-tables by + default. */ +#undef TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT +#define TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT 1 +#undef TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT +#define TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT 1 diff --git a/gcc/config/i386/linux64.h b/gcc/config/i386/linux64.h index 33b4dc9..5a02205 100644 --- a/gcc/config/i386/linux64.h +++ b/gcc/config/i386/linux64.h @@ -123,3 +123,10 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see x86_64 glibc provides it in %fs:0x28. */ #define TARGET_THREAD_SSP_OFFSET (TARGET_64BIT ? 0x28 : 0x14) #endif + +/* Turn on -fomit-frame-pointer and -fasynchronous-unwind-tables by + default. */ +#undef TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT +#define TARGET_SUBTARGET32_OMIT_FRAME_POINTER_DEFAULT 1 +#undef TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT +#define TARGET_SUBTARGET32_ASYNCHRONOUS_UNWIND_TABLES_DEFAULT 1 diff --git a/gcc/testsuite/gcc.target/i386/frame-pointer-1.c b/gcc/testsuite/gcc.target/i386/frame-pointer-1.c new file mode 100644 index 0000000..2495d09 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/frame-pointer-1.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mtune=i686" } */ +/* { dg-require-effective-target ilp32 } */ + +void bar (int); + +void +foo (void) +{ + bar (1); +} diff --git a/gcc/testsuite/gcc.target/i386/frame-pointer-2.c b/gcc/testsuite/gcc.target/i386/frame-pointer-2.c new file mode 100644 index 0000000..1478aba --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/frame-pointer-2.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mtune=i686 -mno-accumulate-outgoing-args" } */ +/* { dg-require-effective-target ilp32 } */ + +void bar (int); + +void +foo (void) +{ + bar (1); +} diff --git a/gcc/testsuite/gcc.target/i386/frame-pointer-3.c b/gcc/testsuite/gcc.target/i386/frame-pointer-3.c new file mode 100644 index 0000000..2ff965f --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/frame-pointer-3.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mtune=i686 -mpush-args" } */ +/* { dg-require-effective-target ilp32 } */ + +void bar (int); + +void +foo (void) +{ + bar (1); +} diff --git a/gcc/testsuite/gcc.target/i386/frame-pointer-4.c b/gcc/testsuite/gcc.target/i386/frame-pointer-4.c new file mode 100644 index 0000000..2b1bf52 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/frame-pointer-4.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -mtune=i686 -mpush-args -mno-accumulate-outgoing-args" } */ +/* { dg-require-effective-target ilp32 } */ + +void bar (int); + +void +foo (void) +{ + bar (1); +}