[cmake] Add an option to build llvm with IR PGO

This adds an LLVM_ENABLE_IR_PGO option to enable building llvm and its
tools with IR PGO instrumentation.

Usage: -DLLVM_BUILD_INSTRUMENTED=On -DLLVM_ENABLE_IR_PGO=On (both
options must be enabled)

Differential Revision: https://reviews.llvm.org/D38066

llvm-svn: 313770
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 0121286..76683c3 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -730,13 +730,27 @@
   message(FATAL_ERROR "Exception handling requires RTTI. You must set LLVM_ENABLE_RTTI to ON")
 endif()
 
+option(LLVM_ENABLE_IR_PGO "Build LLVM and tools with IR PGO instrumentation (experimental)" Off)
+mark_as_advanced(LLVM_ENABLE_IR_PGO)
+
 option(LLVM_BUILD_INSTRUMENTED "Build LLVM and tools with PGO instrumentation" Off)
 mark_as_advanced(LLVM_BUILD_INSTRUMENTED)
-append_if(LLVM_BUILD_INSTRUMENTED "-fprofile-instr-generate='${LLVM_PROFILE_FILE_PATTERN}'"
-  CMAKE_CXX_FLAGS
-  CMAKE_C_FLAGS
-  CMAKE_EXE_LINKER_FLAGS
-  CMAKE_SHARED_LINKER_FLAGS)
+
+if (LLVM_BUILD_INSTRUMENTED)
+  if (LLVM_ENABLE_IR_PGO)
+    append("-fprofile-generate='${LLVM_PROFILE_DATA_DIR}'"
+      CMAKE_CXX_FLAGS
+      CMAKE_C_FLAGS
+      CMAKE_EXE_LINKER_FLAGS
+      CMAKE_SHARED_LINKER_FLAGS)
+  else()
+    append("-fprofile-instr-generate='${LLVM_PROFILE_FILE_PATTERN}'"
+      CMAKE_CXX_FLAGS
+      CMAKE_C_FLAGS
+      CMAKE_EXE_LINKER_FLAGS
+      CMAKE_SHARED_LINKER_FLAGS)
+  endif()
+endif()
 
 option(LLVM_BUILD_INSTRUMENTED_COVERAGE "Build LLVM and tools with Code Coverage instrumentation" Off)
 mark_as_advanced(LLVM_BUILD_INSTRUMENTED_COVERAGE)