[BOLT][NFC] Use LLVM_REVISION instead of BOLT_VERSION_STRING

[Amir]

Summary

Remove duplicate version string identification

[rafauler]

LGTM

bolt/CMakeLists.txt

ExternalProject_Add(bolt_rt
     )
   install(CODE "execute_process\(COMMAND \${CMAKE_COMMAND} -DCMAKE_INSTALL_PREFIX=\${CMAKE_INSTALL_PREFIX} -P ${CMAKE_CURRENT_BINARY_DIR}/bolt_rt-bins/cmake_install.cmake \)"
     COMPONENT bolt)
   add_llvm_install_targets(install-bolt_rt
     DEPENDS bolt_rt bolt
     COMPONENT bolt)
 endif()
 
-# Get the current git revision for BOLT.
-find_program(git_executable NAMES git git.exe git.cmd)
-if (git_executable)
-  execute_process(COMMAND ${git_executable} rev-parse HEAD
-    WORKING_DIRECTORY ${LLVM_MAIN_SRC_DIR}
-    TIMEOUT 5
-    RESULT_VARIABLE git_result
-    OUTPUT_VARIABLE git_output)
-  if( git_result EQUAL 0 )
-    string(STRIP "${git_output}" git_ref_id)
-    set(BOLT_REVISION "${git_ref_id}")
-  endif()
-endif()
-
 find_program(GNU_LD_EXECUTABLE NAMES ${LLVM_DEFAULT_TARGET_TRIPLE}-ld.bfd ld.bfd DOC "GNU ld")
 
-# If we can't find a revision, set it to "<unknown>".
-if (NOT BOLT_REVISION)
-  set(BOLT_REVISION "<unknown>")
-endif()
-
-configure_file(
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/bolt/Utils/BoltRevision.inc.in
-  ${CMAKE_CURRENT_BINARY_DIR}/include/bolt/Utils/BoltRevision.inc)
-
 include_directories(
   ${CMAKE_CURRENT_SOURCE_DIR}/include
   ${CMAKE_CURRENT_BINARY_DIR}/include
   )
 
 add_subdirectory(lib)
 add_subdirectory(tools)
 

bolt/include/bolt/Utils/BoltRevision.inc.in

-#define BOLT_VERSION_STRING "@BOLT_REVISION@"

bolt/lib/Utils/CommandLineOpts.cpp

 //===- bolt/Utils/CommandLineOpts.cpp - BOLT CLI options ------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // BOLT CLI options
 //
 //===----------------------------------------------------------------------===//
 
 #include "bolt/Utils/CommandLineOpts.h"
-#include "bolt/Utils/BoltRevision.inc"
+#include "llvm/Support/VCSRevision.h"
 
 using namespace llvm;
 
 namespace llvm {
 namespace bolt {
-const char *BoltRevision = BOLT_VERSION_STRING;
+const char *BoltRevision = LLVM_REVISION;
 }
 }
 
 namespace opts {
 
 bool HeatmapMode = false;
 bool LinuxKernelMode = false;