Disable clang's SLP vectorizer.

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 3524 matching lines @@
                   'release_optimize%': 's',
                 },
                 'ldflags': [
                   # Warn in case of text relocations.
                   '-Wl,--warn-shared-textrel',
                 ],
               }],
               ['clang==1', {
                 'cflags!': [
                   '-fno-ident',
                 ],

[Nico, 2014/07/18 18:40:44]

Does it work if you add

  'cflags': [ '-fno-slp-vectorize' ],

here?

               }],
               ['profiling==1', {
                 'cflags': [
                   '-fno-omit-frame-pointer',
                   '-g',
                 ],
                 'conditions' : [
                   ['profiling_full_stack_frames==1', {
                     'cflags': [
                       '-fno-inline',
@@ skipping 340 matching lines @@
               # this is worth fixing.
               '-Wno-c++11-narrowing',
 
               # TODO(thakis): Remove, http://crbug.com/263960
               '-Wno-reserved-user-defined-literal',
 
               # Clang considers the `register` keyword as deprecated, but e.g.
               # code generated by flex (used in angle) contains that keyword.
               # http://crbug.com/255186
               '-Wno-deprecated-register',
+
+              # TODO(thakis): Remove once http://llvm.org/PR20354 is fixed
+              # and the fix is in chromium.
+              '-fno-slp-vectorize',
             ],
             'cflags!': [
               # Clang doesn't seem to know know this flag.
               '-mfpmath=sse',
             ],
             'cflags_cc': [
               # See the comment in the Mac section for what it takes to move
               # this to -std=c++11.
               '-std=gnu++11',
             ],
@@ skipping 820 matching lines @@
                 # e.g. code generated by flex (used in angle) contains that
                 # keyword. http://crbug.com/255186
                 '-Wno-deprecated-register',
 
                 # This warns on selectors from Cocoa headers (-length, -set).
                 # cfe-dev is currently discussing the merits of this warning.
                 # TODO(thakis): Reevaluate what to do with this, based one
                 # cfe-dev discussion.
                 '-Wno-selector-type-mismatch',
               ],
+              'OTHER_CFLAGS': [
+                # TODO(thakis): Remove once http://llvm.org/PR20354 is fixed
+                # and the fix is in chromium.
+                '-fno-slp-vectorize',
+              ],
 
               'conditions': [
                 ['clang_xcode==0', {
                   'CC': '$(SOURCE_ROOT)/<(clang_dir)/clang',
                   'LDPLUSPLUS': '$(SOURCE_ROOT)/<(clang_dir)/clang++',
                 }],
               ],
             }],
             ['clang==1 and clang_xcode==0 and clang_use_chrome_plugins==1', {
               'OTHER_CFLAGS': [
@@ skipping 890 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }