Clang update.py: enable debug info for ToT builds

tools/clang/scripts/update.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This script is used to download prebuilt clang binaries.
 
 It is also used by package.py to build the prebuilt clang binaries."""
 
 import argparse
@@ skipping 452 matching lines @@
     # compiler, etc.) find the .so.
     libstdcpp = subprocess.check_output(
         [cxx, '-print-file-name=libstdc++.so.6']).rstrip()
     os.environ['LD_LIBRARY_PATH'] = os.path.dirname(libstdcpp)
 
   cflags = []
   cxxflags = []
   ldflags = []
 
   base_cmake_args = ['-GNinja',
-                     '-DCMAKE_BUILD_TYPE=Release',
                      '-DLLVM_ENABLE_ASSERTIONS=ON',
                      '-DLLVM_ENABLE_THREADS=OFF',
                      '-DLLVM_ENABLE_TIMESTAMPS=OFF',
                      # Statically link MSVCRT to avoid DLL dependencies.
                      '-DLLVM_USE_CRT_RELEASE=MT',
                      ]
 
+  if use_head_revision:
+    # For ToT builds, which are used to catch compiler bugs early, enable debug
+    # info for better backtraces when crashing.
+    base_cmake_args += ['-DCMAKE_BUILD_TYPE=RelWithDebInfo']
+  else:
+    base_cmake_args += ['-DCMAKE_BUILD_TYPE=Release']
+
   binutils_incdir = ''
   if sys.platform.startswith('linux'):
     binutils_incdir = os.path.join(BINUTILS_DIR, 'Linux_x64/Release/include')
 
   if args.bootstrap:
     print 'Building bootstrap compiler'
     EnsureDirExists(LLVM_BOOTSTRAP_DIR)
     os.chdir(LLVM_BOOTSTRAP_DIR)
     bootstrap_args = base_cmake_args + [
         '-DLLVM_BINUTILS_INCDIR=' + binutils_incdir,
@@ skipping 154 matching lines @@
     libstdcpp = subprocess.check_output(
         [cxx] + cxxflags + ['-print-file-name=libstdc++.so.6']).rstrip()
     CopyFile(libstdcpp, os.path.join(LLVM_BUILD_DIR, 'lib'))
 
   RunCommand(['ninja'], msvc_arch='x64')
 
   if args.tools:
     # If any Chromium tools were built, install those now.
     RunCommand(['ninja', 'cr-install'], msvc_arch='x64')
 
-  if sys.platform == 'darwin':
-    # See http://crbug.com/256342
-    RunCommand(['strip', '-x', os.path.join(LLVM_BUILD_DIR, 'bin', 'clang')])
-  elif sys.platform.startswith('linux'):
-    RunCommand(['strip', os.path.join(LLVM_BUILD_DIR, 'bin', 'clang')])
+  if not use_head_revision:
+    # Strip the binaries to save size, except for ToT builds.
+    if sys.platform == 'darwin':
+      # See http://crbug.com/256342
+      RunCommand(['strip', '-x', os.path.join(LLVM_BUILD_DIR, 'bin', 'clang')])
+    elif sys.platform.startswith('linux'):
+      RunCommand(['strip', os.path.join(LLVM_BUILD_DIR, 'bin', 'clang')])
 
   # TODO(thakis): Check that `clang --version` matches VERSION.
 
   # Do an out-of-tree build of compiler-rt.
   # On Windows, this is used to get the 32-bit ASan run-time.
   # TODO(hans): Remove once the regular build above produces this.
   # On Mac and Linux, this is used to get the regular 64-bit run-time.
   # Do a clobbered build due to cmake changes.
   if os.path.isdir(COMPILER_RT_BUILD_DIR):
     RmTree(COMPILER_RT_BUILD_DIR)
@@ skipping 225 matching lines @@
     args.force_local_build = True
     if 'OS=android' not in os.environ.get('GYP_DEFINES', ''):
       # Only build the Android ASan rt on ToT bots when targetting Android.
       args.with_android = False
 
   return UpdateClang(args)
 
 
 if __name__ == '__main__':
   sys.exit(main())