Build code coverage tools with LLVM_ENABLE_THREADS enabled + minor refactoring.

Threaded versions of the tools make processing code coverage data and generating
code coverage reports an order of magnitude faster. See the experiments data
in https://bugs.chromium.org/p/chromium/issues/detail?id=759794#c34.

Bug: 759794
Change-Id: Ia5776de8d250d2e4bb23de79dd921e22e78a3095
Reviewed-on: https://chromium-review.googlesource.com/825985Reviewed-by: Hans Wennborg <hans@chromium.org>
Reviewed-by: Abhishek Arya <inferno@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524199}

tools/clang/scripts/update.py

@@ -51,7 +51,7 @@ LLVM_BOOTSTRAP_INSTALL_DIR = os.path.join(THIRD_PARTY_DIR,
 CHROME_TOOLS_SHIM_DIR = os.path.join(LLVM_DIR, 'tools', 'chrometools')
 LLVM_BUILD_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'llvm-build',
                               'Release+Asserts')
-LLD_BUILD_DIR = os.path.join(LLVM_BUILD_DIR, 'lld')
+THREADS_ENABLED_BUILD_DIR = os.path.join(LLVM_BUILD_DIR, 'threads_enabled')
 COMPILER_RT_BUILD_DIR = os.path.join(LLVM_BUILD_DIR, 'compiler-rt')
 CLANG_DIR = os.path.join(LLVM_DIR, 'tools', 'clang')
 LLD_DIR = os.path.join(LLVM_DIR, 'tools', 'lld')
@@ -614,22 +614,27 @@ def UpdateClang(args):
     deployment_env = os.environ.copy()
     deployment_env['MACOSX_DEPLOYMENT_TARGET'] = deployment_target
 
-  # Build lld. This is done separately from the rest of the build because lld
-  # requires threading support.
-  print 'Building lld'
-  if os.path.exists(LLD_BUILD_DIR):
-    RmTree(LLD_BUILD_DIR)
-  EnsureDirExists(LLD_BUILD_DIR)
-  os.chdir(LLD_BUILD_DIR)
+  # Build lld and code coverage tools. This is done separately from the rest of
+  # the build because these tools require threading support.
+  tools_with_threading = [ 'lld', 'llvm-cov', 'llvm-profdata' ]
+  print 'Building the following tools with threading support: %s' % (
+        str(tools_with_threading))
 
-  lld_cmake_args = base_cmake_args + [
+  if os.path.exists(THREADS_ENABLED_BUILD_DIR):
+    RmTree(THREADS_ENABLED_BUILD_DIR)
+  EnsureDirExists(THREADS_ENABLED_BUILD_DIR)
+  os.chdir(THREADS_ENABLED_BUILD_DIR)
+
+  threads_enabled_cmake_args = base_cmake_args + [
       '-DCMAKE_C_FLAGS=' + ' '.join(cflags),
       '-DCMAKE_CXX_FLAGS=' + ' '.join(cxxflags),
       '-DCMAKE_EXE_LINKER_FLAGS=' + ' '.join(ldflags),
       '-DCMAKE_SHARED_LINKER_FLAGS=' + ' '.join(ldflags),
       '-DCMAKE_MODULE_LINKER_FLAGS=' + ' '.join(ldflags)]
-  if cc is not None:  lld_cmake_args.append('-DCMAKE_C_COMPILER=' + cc)
-  if cxx is not None: lld_cmake_args.append('-DCMAKE_CXX_COMPILER=' + cxx)
+  if cc is not None:
+    threads_enabled_cmake_args.append('-DCMAKE_C_COMPILER=' + cc)
+  if cxx is not None:
+    threads_enabled_cmake_args.append('-DCMAKE_CXX_COMPILER=' + cxx)
 
   if args.lto_lld:
     # Build lld with LTO. That speeds up the linker by ~10%.
@@ -641,16 +646,16 @@ def UpdateClang(args):
     # llvm-ranlib do, so use them.
     ar = os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR, 'bin', 'llvm-ar')
     ranlib = os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR, 'bin', 'llvm-ranlib')
-    lld_cmake_args += [
+    threads_enabled_cmake_args += [
         '-DCMAKE_AR=' + ar,
         '-DCMAKE_RANLIB=' + ranlib,
         '-DLLVM_ENABLE_LTO=thin',
         '-DLLVM_USE_LINKER=lld']
 
   RmCmakeCache('.')
-  RunCommand(['cmake'] + lld_cmake_args + [LLVM_DIR], msvc_arch='x64',
-             env=deployment_env)
-  RunCommand(['ninja', 'lld'], msvc_arch='x64')
+  RunCommand(['cmake'] + threads_enabled_cmake_args + [LLVM_DIR],
+             msvc_arch='x64', env=deployment_env)
+  RunCommand(['ninja'] + tools_with_threading, msvc_arch='x64')
 
   # Build clang and other tools.
   CreateChromeToolsShim()
@@ -681,14 +686,15 @@ def UpdateClang(args):
              msvc_arch='x64', env=deployment_env)
   RunCommand(['ninja'], msvc_arch='x64')
 
-  # Copy in the threaded version of lld.
+  # Copy in the threaded versions of lld and other tools.
   if sys.platform == 'win32':
-    CopyFile(os.path.join(LLD_BUILD_DIR, 'bin', 'lld-link.exe'),
+    CopyFile(os.path.join(THREADS_ENABLED_BUILD_DIR, 'bin', 'lld-link.exe'),
              os.path.join(LLVM_BUILD_DIR, 'bin'))
-    CopyFile(os.path.join(LLD_BUILD_DIR, 'bin', 'lld.pdb'),
+    CopyFile(os.path.join(THREADS_ENABLED_BUILD_DIR, 'bin', 'lld.pdb'),
              os.path.join(LLVM_BUILD_DIR, 'bin'))
   else:
-    CopyFile(os.path.join(LLD_BUILD_DIR, 'bin', 'lld'),
+    for tool in tools_with_threading:
+      CopyFile(os.path.join(THREADS_ENABLED_BUILD_DIR, 'bin', tool),
                os.path.join(LLVM_BUILD_DIR, 'bin'))
 
   if chrome_tools: