[utils] Fix _run_benchmark in collect_and_build_with_pgo.py

[MaskRay]

Summary

Also fix a FIXME in _build_stage1_clang: clang llvm-profdata profile are sufficient

[MaskRay]

.

[george.burgess.iv]

LGTM assuming the _run_benchmark changes are undone.

Thank you!

utils/collect_and_build_with_pgo.py

57

Please put this back; it should've been fixed by r345461. The intent was to run this in the instrumented clang's directory for extra coverage. Instrumentation makes the testing phase way slower, but given that this is already four clean builds of clang/llvm anyway, ...

If r345461 doesn't solve the problem you're seeing, more details would be appreciated. :)

utils/collect_and_build_with_pgo.py

 # ${out_dir} will magically have the profiles go to the right place.
 #
 # You may assume that out_dir is a freshly-built directory that you can reach
 # in to build more things, if you'd like.
 def _run_benchmark(env, out_dir, include_debug_info):
     """The 'benchmark' we run to generate profile data."""
     target_dir = env.output_subdir('instrumentation_run')
 
-    # `check-llvm` and `check-clang` are cheap ways to increase coverage. The
-    # former lets us touch on the non-x86 backends a bit if configured, and the
-    # latter gives us more C to chew on (and will send us through diagnostic
-    # paths a fair amount, though the `if (stuff_is_broken) { diag() ... }`
-    # branches should still heavily be weighted in the not-taken direction,
-    # since we built all of LLVM/etc).
-    _build_things_in(env, out_dir, what=['check-llvm', 'check-clang'])
-
     # Building tblgen gets us coverage; don't skip it. (out_dir may also not
     # have them anyway, but that's less of an issue)
     cmake = _get_cmake_invocation_for_bootstrap_from(
         env, out_dir, skip_tablegens=False)
 
     if include_debug_info:
         cmake.add_flag('CMAKE_BUILD_TYPE', 'RelWithDebInfo')
 
     _run_fresh_cmake(env, cmake, target_dir)
 
     # Just build all the things. The more data we have, the better.
     _build_things_in(env, target_dir, what=['all'])
 
+    # `check-llvm` and `check-clang` are cheap ways to increase coverage. The
+    # former lets us touch on the non-x86 backends a bit if configured, and the
+    # latter gives us more C to chew on (and will send us through diagnostic
+    # paths a fair amount, though the `if (stuff_is_broken) { diag() ... }`
+    # branches should still heavily be weighted in the not-taken direction,
+    # since we built all of LLVM/etc).
+    _build_things_in(env, target_dir, what=['check-llvm', 'check-clang'])
 
 ### Script
 
 
 class CmakeInvocation:
     _cflags = ['CMAKE_C_FLAGS', 'CMAKE_CXX_FLAGS']
     _ldflags = [
         'CMAKE_EXE_LINKER_FLAGS',
def _run_fresh_cmake(env, cmake, target_dir):
     env.run_command(
         cmake_args, cwd=target_dir, check=True, silent_unless_error=True)
 
 
 def _build_stage1_clang(env):
     target_dir = env.output_subdir('stage1')
     cmake = _get_default_cmake_invocation(env)
     _run_fresh_cmake(env, cmake, target_dir)
-
-    # FIXME: The full build here is somewhat unfortunate. It's primarily
-    # because I don't know what to call libclang_rt.profile for arches that
-    # aren't x86_64 (and even then, it's in a subdir that contains clang's
-    # current version). It would be nice to figure out what target I can
-    # request to magically have libclang_rt.profile built for ${host}
-    _build_things_in(env, target_dir, what=['all'])
+    _build_things_in(env, target_dir, what=['clang', 'llvm-profdata', 'profile'])
     return target_dir
 
 
 def _generate_instrumented_clang_profile(env, stage1_dir, profile_dir,
                                          output_file):
     llvm_profdata = os.path.join(stage1_dir, 'bin', 'llvm-profdata')
     if env.dry_run:
         profiles = [os.path.join(profile_dir, '*.profraw')]