================
@@ -26,9 +30,23 @@ if(LLVM_BUILD_INSTRUMENTED)
message(STATUS "To enable merging PGO data LLVM_PROFDATA has to point to
llvm-profdata")
else()
add_custom_target(generate-profdata
- COMMAND "${Python3_EXECUTABLE}"
${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py merge ${LLVM_PROFDATA}
${CMAKE_CURRENT_BINARY_DIR}/clang.profdata ${CMAKE_CURRENT_BINARY_DIR}
+ COMMAND "${Python3_EXECUTABLE}"
${CMAKE_CURRENT_SOURCE_DIR}/perf-helper.py merge ${LLVM_PROFDATA}
${CMAKE_CURRENT_BINARY_DIR}/clang.profdata ${CMAKE_CURRENT_BINARY_DIR}
${CMAKE_BINARY_DIR}/profiles/
COMMENT "Merging profdata"
DEPENDS generate-profraw)
+ if (CLANG_PGO_TRAINING_DATA_SOURCE_DIR)
+ llvm_ExternalProject_Add(generate-profraw-external
${CLANG_PGO_TRAINING_DATA_SOURCE_DIR}
+ USE_TOOLCHAIN EXLUDE_FROM_ALL NO_INSTALL DEPENDS
generate-profraw)
+ add_dependencies(generate-profdata generate-profraw-external)
+ else()
+ # Default to compiling a file from clang. This also builds all the
+ # dependencies needed to build this file, like TableGen.
+ set(generate_profraw_clang_sema
tools/clang/lib/Sema/CMakeFiles/obj.clangSema.dir/Sema.cpp.o)
+ llvm_ExternalProject_Add(generate-profraw-clang
${CMAKE_CURRENT_SOURCE_DIR}/../../../llvm
+ USE_TOOLCHAIN EXLUDE_FROM_ALL NO_INSTALL DEPENDS generate-profraw
+ EXTRA_TARGETS generate_profraw_clang_sema
----------------
tstellar wrote:
> If you're not concerned about the efficacy of the PGO build, I'm not sure why
> the existing single hello_world is a bad default. It isn't great but it is
> stable and something. If you want something that gives better performance
> then you must care about the efficacy, and I think you need to be somewhat
> concerned about the stability of those results, otherwise what's the point?
I'm concerned about the efficacy if it is 0%, but not really concerned if it
bounces around between say 10 and 25 % based on updates to the file we are
using to train.
I tested with the existing default (hello_world) and I didn't see any
performance improvements from that. We also did some manual builds (not using
the 2-stage PGO cache) and could not get any performance gains for using a
hello world source. How certain are we that hello_world is enough to get
performance improvements from PGO? Has anyone tested this recently? I will
re-run my tests just to double check.
https://github.com/llvm/llvm-project/pull/77347
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