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

third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp

Index: third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
diff --git a/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp b/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
index 1d164f510a36de4ecb3328e6c80065f4913eca5d..7c609c5bba5ab1b1a181be5121b44acbbaf306b3 100644
--- a/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
+++ b/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
@@ -5,6 +5,7 @@
 #include "platform/heap/StackFrameDepth.h"
 
 #include "public/platform/Platform.h"
+#include "wtf/StackUtil.h"
 
 #if OS(WIN)
 #include <stddef.h>
@@ -38,7 +39,7 @@ uintptr_t StackFrameDepth::getFallbackStackLimit() {
 void StackFrameDepth::enableStackLimit() {
   // All supported platforms will currently return a non-zero estimate,
   // except if ASan is enabled.
-  size_t stackSize = getUnderestimatedStackSize();
+  size_t stackSize = WTF::getUnderestimatedStackSize();
   if (!stackSize) {
     m_stackFrameLimit = getFallbackStackLimit();
     return;
@@ -46,7 +47,7 @@ void StackFrameDepth::enableStackLimit() {
 
   static const int kStackRoomSize = 1024;
 
-  Address stackBase = reinterpret_cast<Address>(getStackStart());
+  Address stackBase = reinterpret_cast<Address>(WTF::getStackStart());
   RELEASE_ASSERT(stackSize > static_cast<const size_t>(kStackRoomSize));
   size_t stackRoom = stackSize - kStackRoomSize;
   RELEASE_ASSERT(stackBase > reinterpret_cast<Address>(stackRoom));
@@ -58,127 +59,4 @@ void StackFrameDepth::enableStackLimit() {
     disableStackLimit();
 }
 
-size_t StackFrameDepth::getUnderestimatedStackSize() {
-// FIXME: ASAN bot uses a fake stack as a thread stack frame,
-// and its size is different from the value which APIs tells us.
-#if defined(ADDRESS_SANITIZER)
-  return 0;
-#endif
-
-// FIXME: On Mac OSX and Linux, this method cannot estimate stack size
-// correctly for the main thread.
-
-#if defined(__GLIBC__) || OS(ANDROID) || OS(FREEBSD)
-  // pthread_getattr_np() can fail if the thread is not invoked by
-  // pthread_create() (e.g., the main thread of webkit_unit_tests).
-  // If so, a conservative size estimate is returned.
-
-  pthread_attr_t attr;
-  int error;
-#if OS(FREEBSD)
-  pthread_attr_init(&attr);
-  error = pthread_attr_get_np(pthread_self(), &attr);
-#else
-  error = pthread_getattr_np(pthread_self(), &attr);
-#endif
-  if (!error) {
-    void* base;
-    size_t size;
-    error = pthread_attr_getstack(&attr, &base, &size);
-    RELEASE_ASSERT(!error);
-    pthread_attr_destroy(&attr);
-    return size;
-  }
-#if OS(FREEBSD)
-  pthread_attr_destroy(&attr);
-#endif
-
-  // Return a 512k stack size, (conservatively) assuming the following:
-  //  - that size is much lower than the pthreads default (x86 pthreads has a 2M
-  //    default.)
-  //  - no one is running Blink with an RLIMIT_STACK override, let alone as
-  //    low as 512k.
-  //
-  return 512 * 1024;
-#elif OS(MACOSX)
-  // pthread_get_stacksize_np() returns too low a value for the main thread on
-  // OSX 10.9,
-  // http://mail.openjdk.java.net/pipermail/hotspot-dev/2013-October/011369.html
-  //
-  // Multiple workarounds possible, adopt the one made by
-  // https://github.com/robovm/robovm/issues/274
-  // (cf.
-  // https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/Multithreading/CreatingThreads/CreatingThreads.html
-  // on why hardcoding sizes is reasonable.)
-  if (pthread_main_np()) {
-#if defined(IOS)
-    pthread_attr_t attr;
-    pthread_attr_init(&attr);
-    size_t guardSize = 0;
-    pthread_attr_getguardsize(&attr, &guardSize);
-    // Stack size for the main thread is 1MB on iOS including the guard page
-    // size.
-    return (1 * 1024 * 1024 - guardSize);
-#else
-    // Stack size for the main thread is 8MB on OSX excluding the guard page
-    // size.
-    return (8 * 1024 * 1024);
-#endif
-  }
-  return pthread_get_stacksize_np(pthread_self());
-#elif OS(WIN) && COMPILER(MSVC)
-  return ThreadState::current()->threadStackSize();
-#else
-#error "Stack frame size estimation not supported on this platform."
-  return 0;
-#endif
-}
-
-void* StackFrameDepth::getStackStart() {
-#if defined(__GLIBC__) || OS(ANDROID) || OS(FREEBSD)
-  pthread_attr_t attr;
-  int error;
-#if OS(FREEBSD)
-  pthread_attr_init(&attr);
-  error = pthread_attr_get_np(pthread_self(), &attr);
-#else
-  error = pthread_getattr_np(pthread_self(), &attr);
-#endif
-  if (!error) {
-    void* base;
-    size_t size;
-    error = pthread_attr_getstack(&attr, &base, &size);
-    RELEASE_ASSERT(!error);
-    pthread_attr_destroy(&attr);
-    return reinterpret_cast<uint8_t*>(base) + size;
-  }
-#if OS(FREEBSD)
-  pthread_attr_destroy(&attr);
-#endif
-#if defined(__GLIBC__)
-  // pthread_getattr_np can fail for the main thread. In this case
-  // just like NaCl we rely on the __libc_stack_end to give us
-  // the start of the stack.
-  // See https://code.google.com/p/nativeclient/issues/detail?id=3431.
-  return __libc_stack_end;
-#else
-  ASSERT_NOT_REACHED();
-  return nullptr;
-#endif
-#elif OS(MACOSX)
-  return pthread_get_stackaddr_np(pthread_self());
-#elif OS(WIN) && COMPILER(MSVC)
-// On Windows stack limits for the current thread are available in
-// the thread information block (TIB). Its fields can be accessed through
-// FS segment register on x86 and GS segment register on x86_64.
-#ifdef _WIN64
-  return reinterpret_cast<void*>(__readgsqword(offsetof(NT_TIB64, StackBase)));
-#else
-  return reinterpret_cast<void*>(__readfsdword(offsetof(NT_TIB, StackBase)));
-#endif
-#else
-#error Unsupported getStackStart on this platform.
-#endif
-}
-
 }  // namespace blink