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

[Xinliang David Li via llvm-commits]

Let's stick to Linux for now (and grow to other ELF based platforms
later). I will update the patch.

David

On Tue, Oct 6, 2015 at 12:04 AM, Justin Bogner <mail at justinbogner.com> wrote:
> 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}
>>
>>