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Only use PGO data if clang can read it #114005

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Merged
merged 2 commits into from
Mar 28, 2025
Merged

Only use PGO data if clang can read it #114005

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6d92bb5
Only use PGO data on recent enough clang
akoeplinger Mar 28, 2025
33c5901
Check if profile data is compatible instead
akoeplinger Mar 28, 2025
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25 changes: 12 additions & 13 deletions src/coreclr/pgosupport.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,11 @@ include(CheckCXXCompilerFlag)
# VC++ guarantees support for LTCG (LTO's equivalent)
if(NOT WIN32)
# Function required to give CMAKE_REQUIRED_* local scope
function(check_have_lto)
set(CMAKE_REQUIRED_FLAGS -flto)
function(check_have_lto_and_pgodata_supported profile_path)
set(CMAKE_REQUIRED_FLAGS "-flto -fprofile-instr-use=${profile_path} -Wno-profile-instr-out-of-date -Wno-profile-instr-unprofiled")
set(CMAKE_REQUIRED_LIBRARIES -flto)
check_cxx_source_compiles("int main() { return 0; }" HAVE_LTO)
endfunction(check_have_lto)
check_have_lto()
check_cxx_source_compiles("int main() { return 0; }" HAVE_LTO_AND_PGO_DATA_SUPPORTED)
endfunction(check_have_lto_and_pgodata_supported)

check_cxx_compiler_flag(-faligned-new COMPILER_SUPPORTS_F_ALIGNED_NEW)
endif(NOT WIN32)
Expand Down Expand Up @@ -52,17 +51,17 @@ function(add_pgo TargetName)
add_compile_definitions(WITH_NATIVE_PGO)
else(CLR_CMAKE_HOST_WIN32)
if(UPPERCASE_CMAKE_BUILD_TYPE STREQUAL RELEASE OR UPPERCASE_CMAKE_BUILD_TYPE STREQUAL RELWITHDEBINFO)
if((CMAKE_CXX_COMPILER_ID MATCHES "Clang") AND (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 16))
if(HAVE_LTO)
if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
check_have_lto_and_pgodata_supported(${ProfilePath})
if(HAVE_LTO_AND_PGO_DATA_SUPPORTED)
message(STATUS "Enabling profile guided optimizations for ${TargetName}")
target_compile_options(${TargetName} PRIVATE -flto -fprofile-instr-use=${ProfilePath} -Wno-profile-instr-out-of-date -Wno-profile-instr-unprofiled)
set_property(TARGET ${TargetName} APPEND_STRING PROPERTY LINK_FLAGS " -flto -fprofile-instr-use=${ProfilePath}")
add_compile_definitions(WITH_NATIVE_PGO)
else(HAVE_LTO)
message(WARNING "LTO is not supported, skipping profile guided optimizations")
endif(HAVE_LTO)
else((CMAKE_CXX_COMPILER_ID MATCHES "Clang") AND (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 16))
message(WARNING "PGO is not supported; Clang 16 or later is required for profile guided optimizations")
endif((CMAKE_CXX_COMPILER_ID MATCHES "Clang") AND (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 16))
else(HAVE_LTO_AND_PGO_DATA_SUPPORTED)
message(WARNING "LTO is not supported or PGO optimization data not compatible, skipping profile guided optimizations for ${TargetName}")
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If we pass msbuild's OfficialBuildId != '' to cmake as CLR_IS_OFFICIAL_BUILD e.g., then we can use it to error out to make the problem visible (probably we don't want it to slip through unnoticed).

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good idea, but that is also set for source-build and afaik they can't use our PGO packages so we shouldn't error in that case. I'd do that in a separate PR.

endif(HAVE_LTO_AND_PGO_DATA_SUPPORTED)
endif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
endif(UPPERCASE_CMAKE_BUILD_TYPE STREQUAL RELEASE OR UPPERCASE_CMAKE_BUILD_TYPE STREQUAL RELWITHDEBINFO)
endif(CLR_CMAKE_HOST_WIN32)
endif(NOT EXISTS ${ProfilePath})
Expand Down
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