Amir updated this revision to Diff 457102.
Amir added a comment.
Succeeded instrumenting Clang with BOLT
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D132975/new/
https://reviews.llvm.org/D132975
Files:
clang/CMakeLists.txt
clang/cmake/caches/BOLT.cmake
Index: clang/cmake/caches/BOLT.cmake
===================================================================
--- /dev/null
+++ clang/cmake/caches/BOLT.cmake
@@ -0,0 +1,14 @@
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(CLANG_BOLT_INSTRUMENT ON CACHE BOOL "")
+set(CLANG_BOLT_INSTRUMENT_PROJECTS "lld" CACHE STRING "")
+set(CLANG_BOLT_INSTRUMENT_TARGETS "lld" CACHE STRING "")
+set(CMAKE_EXE_LINKER_FLAGS "-Wl,--emit-relocs,-znow" CACHE STRING "")
+
+set(LLVM_ENABLE_PROJECTS "bolt;clang;lld" CACHE STRING "")
+set(LLVM_TARGETS_TO_BUILD Native CACHE STRING "")
+
+# Disable function splitting enabled by default in GCC8+
+if("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
+ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fno-reorder-blocks-and-partition")
+ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-reorder-blocks-and-partition")
+endif()
Index: clang/CMakeLists.txt
===================================================================
--- clang/CMakeLists.txt
+++ clang/CMakeLists.txt
@@ -443,7 +443,7 @@
"HAVE_CLANG_PLUGIN_SUPPORT" OFF)
# If libstdc++ is statically linked, clang-repl needs to statically link libstdc++
-# itself, which is not possible in many platforms because of current limitations in
+# itself, which is not possible in many platforms because of current limitations in
# JIT stack. (more platforms need to be supported by JITLink)
if(NOT LLVM_STATIC_LINK_CXX_STDLIB)
set(HAVE_CLANG_REPL_SUPPORT ON)
@@ -878,6 +878,97 @@
endforeach()
endif()
+if (CLANG_BOLT_INSTRUMENT)
+ set(C_COMPILER "clang.bolt.inst")
+ set(CXX_COMPILER "clang++.bolt.inst")
+ set(C_COMPILER_PATH ${CMAKE_CURRENT_BINARY_DIR}/${C_COMPILER})
+ set(CXX_COMPILER_PATH ${CMAKE_CURRENT_BINARY_DIR}/${CXX_COMPILER})
+
+ # Instrument clang with BOLT
+ add_custom_target(clang-instrumented
+ DEPENDS ${C_COMPILER_PATH}
+ )
+ add_custom_command(OUTPUT ${C_COMPILER_PATH}
+ DEPENDS clang llvm-bolt
+ COMMAND llvm-bolt $<TARGET_FILE:clang> -o ${C_COMPILER_PATH}
+ -instrument --instrumentation-file-append-pid
+ --instrumentation-file=${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+ COMMENT "Instrumenting clang binary with BOLT"
+ VERBATIM
+ )
+
+ # Make a symlink from ${C_COMPILER} to ${CXX_COMPILER}
+ add_custom_target(clang++-instrumented
+ DEPENDS ${CXX_COMPILER_PATH}
+ )
+ add_custom_command(OUTPUT ${CXX_COMPILER_PATH}
+ DEPENDS clang-instrumented
+ COMMAND ${CMAKE_COMMAND} -E create_symlink
+ ${C_COMPILER_PATH}
+ ${CXX_COMPILER_PATH}
+ COMMENT "Creating a symlink from BOLT instrumented clang to clang++"
+ VERBATIM
+ )
+
+ # Configure and build Clang with instrumented Clang to collect the profile
+ set(STAMP_DIR ${CMAKE_CURRENT_BINARY_DIR}/bolt-instrumented-clang-stamps/)
+ set(BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/bolt-instrumented-clang-bins/)
+ set(build_configuration "$<CONFIG>")
+ include(ExternalProject)
+ ExternalProject_Add(bolt-instrumentation-profile
+ DEPENDS clang-instrumented clang++-instrumented
+ PREFIX bolt-instrumentation-profile
+ SOURCE_DIR ${CMAKE_SOURCE_DIR}
+ STAMP_DIR ${STAMP_DIR}
+ BINARY_DIR ${BINARY_DIR}
+ EXCLUDE_FROM_ALL 1
+ CMAKE_ARGS
+ # We shouldn't need to set this here, but INSTALL_DIR doesn't
+ # seem to work, so instead I'm passing this through
+ -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+ -DCMAKE_C_COMPILER=${C_COMPILER_PATH}
+ -DCMAKE_CXX_COMPILER=${CXX_COMPILER_PATH}
+ -DCMAKE_ASM_COMPILER=${C_COMPILER_PATH}
+ -DCMAKE_ASM_COMPILER_ID=Clang
+ -DCMAKE_BUILD_TYPE=Release
+ -DLLVM_ENABLE_PROJECTS=${CLANG_BOLT_INSTRUMENT_PROJECTS}
+ BUILD_COMMAND ${CMAKE_COMMAND} --build ${BINARY_DIR}
+ --config ${build_configuration}
+ --target ${CLANG_BOLT_INSTRUMENT_TARGETS}
+ INSTALL_COMMAND ""
+ STEP_TARGETS configure build
+ USES_TERMINAL_CONFIGURE 1
+ USES_TERMINAL_BUILD 1
+ USES_TERMINAL_INSTALL 1
+ LIST_SEPARATOR |
+ )
+
+ # Merge profiles into one using merge-fdata
+ add_custom_target(clang-bolt-profile
+ DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+ )
+ add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+ DEPENDS merge-fdata bolt-instrumentation-profile-build
+ COMMAND merge-fdata ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata.*
+ -o ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+ COMMENT "Preparing BOLT profile"
+ VERBATIM
+ )
+
+ # Optimize original (pre-bolt) Clang using the collected profile
+ add_custom_target(clang-bolt
+ DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt
+ )
+ add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt
+ DEPENDS clang-bolt-profile
+ COMMAND llvm-bolt $<TARGET_FILE:clang>
+ -o ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt
+ -data ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+ COMMENT "Optimizing Clang with BOLT"
+ VERBATIM
+ )
+endif()
+
if (LLVM_ADD_NATIVE_VISUALIZERS_TO_SOLUTION)
add_subdirectory(utils/ClangVisualizers)
endif()
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