Add build option to specify profdata type

[kongyi]

Summary

There is an option to generate IR profile for LLVM but no way to actually use it. Add an option to choose which type of profdata is given, and default to frontend profile if option is not set to maintain the current behaviour.

llvm/cmake/modules/HandleLLVMOptions.cmake

if (CLANG_CL AND (LLVM_BUILD_INSTRUMENTED OR LLVM_USE_SANITIZER))
   file(TO_CMAKE_PATH "${clang_compiler_rt_file}" clang_compiler_rt_file)
   get_filename_component(clang_runtime_dir "${clang_compiler_rt_file}" DIRECTORY)
   append("/libpath:${clang_runtime_dir}"
     CMAKE_EXE_LINKER_FLAGS
     CMAKE_MODULE_LINKER_FLAGS
     CMAKE_SHARED_LINKER_FLAGS)
 endif()
 
+set(LLVM_PROFDATA_TYPE OFF CACHE STRING "The type of PGO profile used to build LLVM and tools. May be specified as IR or Frontend")
+mark_as_advanced(LLVM_PROFDATA_TYPE)
+string(TOUPPER "${LLVM_PROFDATA_TYPE}" uppercase_LLVM_PROFDATA_TYPE)
 if(LLVM_PROFDATA_FILE AND EXISTS ${LLVM_PROFDATA_FILE})
+  if (uppercase_LLVM_PROFDATA_TYPE STREQUAL "IR")
+    if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" )
+      append("-fprofile-use=\"${LLVM_PROFDATA_FILE}\""
+        CMAKE_CXX_FLAGS
+        CMAKE_C_FLAGS)
+      if(NOT LINKER_IS_LLD_LINK)
+        append("-fprofile-use=\"${LLVM_PROFDATA_FILE}\""
+          CMAKE_EXE_LINKER_FLAGS
+          CMAKE_SHARED_LINKER_FLAGS)
+      endif()
+    else()
+      message(FATAL_ERROR "LLVM_PROFDATA_FILE can only be specified when compiling with clang")
+    endif()
+  else()
     if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" )
       append("-fprofile-instr-use=\"${LLVM_PROFDATA_FILE}\""
         CMAKE_CXX_FLAGS
         CMAKE_C_FLAGS)
       if(NOT LINKER_IS_LLD_LINK)
         append("-fprofile-instr-use=\"${LLVM_PROFDATA_FILE}\""
           CMAKE_EXE_LINKER_FLAGS
           CMAKE_SHARED_LINKER_FLAGS)
       endif()
     else()
       message(FATAL_ERROR "LLVM_PROFDATA_FILE can only be specified when compiling with clang")
     endif()
   endif()
+endif()
 
 option(LLVM_BUILD_INSTRUMENTED_COVERAGE "Build LLVM and tools with Code Coverage instrumentation" Off)
 mark_as_advanced(LLVM_BUILD_INSTRUMENTED_COVERAGE)
 append_if(LLVM_BUILD_INSTRUMENTED_COVERAGE "-fprofile-instr-generate=\"${LLVM_PROFILE_FILE_PATTERN}\" -fcoverage-mapping"
   CMAKE_CXX_FLAGS
   CMAKE_C_FLAGS
   CMAKE_EXE_LINKER_FLAGS
   CMAKE_SHARED_LINKER_FLAGS)