Fast path for ThreadSpecific for main thread on TLS-slow platforms

third_party/WebKit/Source/wtf/WTFThreadData.cpp

 /*
  * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  */
 
 #include "wtf/WTFThreadData.h"
 
+#include "wtf/StackUtil.h"
 #include "wtf/text/AtomicStringTable.h"
 #include "wtf/text/TextCodecICU.h"
 
 namespace WTF {
 
 ThreadSpecific<WTFThreadData>* WTFThreadData::staticData;
 
 WTFThreadData::WTFThreadData()
     : m_atomicStringTable(new AtomicStringTable),
       m_cachedConverterICU(new ICUConverterWrapper),
       m_threadId(internal::currentThreadSyscall()) {}
 
 WTFThreadData::~WTFThreadData() {}
 
+#if OS(WIN) && COMPILER(MSVC)
+size_t WTFThreadData::threadStackSize() {
+  // Needed to bootstrap WTFThreadData on Windows, because this value is needed
+  // before the main thread data is fully initialized.
+  if (WTFThreadData::staticData->isSet())

[Charlie Harrison, 2017/01/18 04:46:55]

if (!WTFThreadData::staticData->isSet())

+    return internal::threadStackSize();
+
+  WTFThreadData& data = wtfThreadData();
+  if (!data.m_threadStackSize)
+    data.m_threadStackSize = internal::threadStackSize();
+  return data.m_threadStackSize;
+}
+#endif
+
 }  // namespace WTF