[PATCH] D13329: [PGO]: Eliminate __llvm_profile_register calls for Linux (compiler_rt)

[Justin Bogner via llvm-commits]

David Li <davidxl at google.com> writes:
> davidxl updated this revision to Diff 36319.
> davidxl added a comment.
>
> This is the latest version that does not rely on linker script.
>
>
> http://reviews.llvm.org/D13329
>
> Files:
>   lib/profile/CMakeLists.txt
>   lib/profile/InstrProfilingPlatformLinux.c
>
> Index: lib/profile/InstrProfilingPlatformLinux.c
> ===================================================================
> --- /dev/null
> +++ lib/profile/InstrProfilingPlatformLinux.c
> @@ -0,0 +1,48 @@
> +/*===- InstrProfilingPlatformLinux.c - Profile data Linux platform ------===*\
> +|*
> +|*                     The LLVM Compiler Infrastructure
> +|*
> +|* This file is distributed under the University of Illinois Open Source
> +|* License. See LICENSE.TXT for details.
> +|*
> +\*===----------------------------------------------------------------------===*/
> +
> +#include "InstrProfiling.h"
> +
> +#if !defined(__APPLE__)
> +#include <stdlib.h>
> +
> +extern __llvm_profile_data __start___llvm_prf_data
> +    __attribute__((visibility("hidden")));
> +extern __llvm_profile_data __stop___llvm_prf_data
> +    __attribute__((visibility("hidden")));
> +extern uint64_t __start___llvm_prf_cnts __attribute__((visibility("hidden")));
> +extern uint64_t __stop___llvm_prf_cnts __attribute__((visibility("hidden")));
> +extern char __start___llvm_prf_names __attribute__((visibility("hidden")));
> +extern char __stop___llvm_prf_names __attribute__((visibility("hidden")));
> +
> +__attribute__((visibility("hidden"))) const __llvm_profile_data *
> +__llvm_profile_begin_data(void) {
> +  return &__start___llvm_prf_data;
> +}
> +__attribute__((visibility("hidden"))) const __llvm_profile_data *
> +__llvm_profile_end_data(void) {
> +  return &__stop___llvm_prf_data;
> +}
> +__attribute__((visibility("hidden"))) const char *__llvm_profile_begin_names(
> +    void) {
> +  return &__start___llvm_prf_names;
> +}
> +__attribute__((visibility("hidden"))) const char *__llvm_profile_end_names(
> +    void) {
> +  return &__stop___llvm_prf_names;
> +}
> +__attribute__((visibility("hidden"))) uint64_t *__llvm_profile_begin_counters(
> +    void) {
> +  return &__start___llvm_prf_cnts;
> +}
> +__attribute__((visibility("hidden"))) uint64_t *__llvm_profile_end_counters(
> +    void) {
> +  return &__stop___llvm_prf_cnts;
> +}
> +#endif
> Index: lib/profile/CMakeLists.txt
> ===================================================================
> --- lib/profile/CMakeLists.txt
> +++ lib/profile/CMakeLists.txt
> @@ -1,23 +1,35 @@
>  add_custom_target(profile)
>  
> -set(PROFILE_SOURCES
> +set(COMMON_SOURCES
>    GCDAProfiling.c
>    InstrProfiling.c
>    InstrProfilingBuffer.c
>    InstrProfilingFile.c
> -  InstrProfilingPlatformDarwin.c
> -  InstrProfilingPlatformOther.c
>    InstrProfilingRuntime.cc
>    InstrProfilingUtil.c)
>  
>  if(APPLE)
> +  set(PROFILE_SOURCES
> +      ${COMMON_SOURCES}
> +      InstrProfilingPlatformDarwin.c)
> +
>    add_compiler_rt_runtime(clang_rt.profile
>      STATIC
>      OS osx
>      ARCHS ${PROFILE_SUPPORTED_ARCH}
>      SOURCES ${PROFILE_SOURCES}
>      PARENT_TARGET profile)
>  else()
> +  if(UNIX)
> +    # Assume Linux

I don't think that's a reasonable assumption. What is the actual
commonality where this works? ELF? GNU tools? Notably, if this works on
the various BSDs this comment is confusing, and if it doesn't the check
is wrong.

> +    set(PROFILE_SOURCES
> +        ${COMMON_SOURCES}
> +        InstrProfilingPlatformLinux.c)

If this does generalize to ELF or GNU we should call it PlatformELF or
PlatformGNU or whatever, so as not to confuse people.

> +  else()
> +    set(PROFILE_SOURCES  
> +        ${COMMON_SOURCES}
> +        InstrProfilingPlatformOther.c)
> +  endif()
>    add_compiler_rt_runtime(clang_rt.profile
>      STATIC
>      ARCHS ${PROFILE_SUPPORTED_ARCH}
>
>