[PATCH] D132975: [clang][BOLT] Add clang-bolt target (WIP)

[Amir Ayupov via Phabricator via cfe-commits]

Amir updated this revision to Diff 456799.
Amir added a comment.

CMAKE_CURRENT_BINARY_DIR already contains bin/


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 +1,12 @@
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(CLANG_BOLT_INSTRUMENT ON CACHE BOOL "")
+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
@@ -878,6 +878,56 @@
   endforeach()
 endif()
 
+if (CLANG_BOLT_INSTRUMENT)
+  find_program(LLVM_BOLT llvm-bolt)
+  find_program(MERGE_FDATA merge-fdata)
+
+  # Instrument clang with BOLT
+  add_custom_target(clang-instrumented
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst
+  )
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst
+    DEPENDS clang
+    COMMAND ${LLVM_BOLT} ${CMAKE_BINARY_DIR}/clang -o
+      ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst
+      -instrument --instrumentation-file-append-pid
+      --instrumentation-file=${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+    COMMENT "Instrumenting clang binary with BOLT"
+    )
+  # Make a symlink from clang.bolt.inst to clang++.bolt.inst
+  add_clang_symlink(${CMAKE_CURRENT_BINARY_DIR}/clang++.bolt.inst
+                    ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst)
+
+  # Configure and build Clang with instrumented Clang to collect the profile
+  include(ExternalProject)
+  ExternalProject_Add(bolt-instrumentation-profile
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst
+    PREFIX bolt-instrumentation-profile
+    SOURCE_DIR ${CMAKE_SOURCE_DIR}
+    CMAKE_ARGS
+                # We shouldn't need to set this here, but INSTALL_DIR doesn't
+                # seem to work, so instead I'm passing this through
+                -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+                -DCMAKE_CXX_COMPILER=${CMAKE_CURRENT_BINARY_DIR}/clang++.bolt.inst
+                -DCMAKE_C_COMPILER=${CMAKE_CURRENT_BINARY_DIR}/clang.bolt.inst
+    STEP_TARGETS configure build install
+  )
+  # Merge profiles into one using merge-fdata
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+    COMMAND ${MERGE_FDATA} ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata.*
+      -o ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+  )
+  # Optimize original (pre-bolt) Clang using the collected profile
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata clang
+    COMMAND ${LLVM_BOLT} ${CMAKE_BINARY_DIR}/clang
+    -o ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt -data ${CMAKE_CURRENT_BINARY_DIR}/prof.fdata
+  )
+  add_custom_target(clang-bolt
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/clang.bolt
+    )
+endif()
+
 if (LLVM_ADD_NATIVE_VISUALIZERS_TO_SOLUTION)
   add_subdirectory(utils/ClangVisualizers)
 endif()


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