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

third_party/WebKit/Source/wtf/ThreadingPthreads.cpp

 /*
  * Copyright (C) 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Justin Haygood (jhaygood@reaktix.com)
  * Copyright (C) 2011 Research In Motion Limited. 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
@@ skipping 85 matching lines @@
 void lockAtomicallyInitializedStaticMutex() {
   DCHECK(atomicallyInitializedStaticMutex);
   atomicallyInitializedStaticMutex->lock();
 }
 
 void unlockAtomicallyInitializedStaticMutex() {
   atomicallyInitializedStaticMutex->unlock();
 }
 
 ThreadIdentifier currentThread() {
-// TLS lookup is fast on these platforms.
-#if defined(__GLIBC__) || OS(ANDROID) || OS(FREEBSD)
   return wtfThreadData().threadId();
-#else
-  // TODO(csharrison): For platforms where TLS lookup is slow, use the hack that
-  // oilpan uses in ThreadState::current() to check if this is the main thread
-  // via stack address.
-  return internal::currentThreadSyscall();
-#endif
 }
 
 MutexBase::MutexBase(bool recursive) {
   pthread_mutexattr_t attr;
   pthread_mutexattr_init(&attr);
   pthread_mutexattr_settype(
       &attr, recursive ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL);
 
   int result = pthread_mutex_init(&m_mutex.m_internalMutex, &attr);
   DCHECK_EQ(result, 0);
@@ skipping 129 matching lines @@
 }
 
 void willCreateThread() {
   s_threadCreated = true;
 }
 #endif
 
 }  // namespace WTF
 
 #endif  // OS(POSIX)