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

third_party/WebKit/Source/wtf/StackUtil.cpp

Index: third_party/WebKit/Source/wtf/StackUtil.cpp
diff --git a/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp b/third_party/WebKit/Source/wtf/StackUtil.cpp
similarity index 68%
copy from third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
copy to third_party/WebKit/Source/wtf/StackUtil.cpp
index 1d164f510a36de4ecb3328e6c80065f4913eca5d..e40048e65762a0fdb7356fc39c0778f505caf22e 100644
--- a/third_party/WebKit/Source/platform/heap/StackFrameDepth.cpp
+++ b/third_party/WebKit/Source/wtf/StackUtil.cpp
@@ -1,10 +1,11 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
+// Copyright 2017 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.
 
-#include "platform/heap/StackFrameDepth.h"
+#include "wtf/StackUtil.h"
 
-#include "public/platform/Platform.h"
+#include "wtf/Assertions.h"
+#include "wtf/WTFThreadData.h"
 
 #if OS(WIN)
 #include <stddef.h>
@@ -14,51 +15,9 @@
 extern "C" void* __libc_stack_end;  // NOLINT
 #endif
 
-namespace blink {
+namespace WTF {
 
-static const char* s_avoidOptimization = nullptr;
-
-// NEVER_INLINE ensures that |dummy| array on configureLimit() is not optimized
-// away, and the stack frame base register is adjusted |kSafeStackFrameSize|.
-NEVER_INLINE static uintptr_t currentStackFrameBaseOnCallee(const char* dummy) {
-  s_avoidOptimization = dummy;
-  return StackFrameDepth::currentStackFrame();
-}
-
-uintptr_t StackFrameDepth::getFallbackStackLimit() {
-  // Allocate an |kSafeStackFrameSize|-sized object on stack and query
-  // stack frame base after it.
-  char dummy[kSafeStackFrameSize];
-
-  // Check that the stack frame can be used.
-  dummy[sizeof(dummy) - 1] = 0;
-  return currentStackFrameBaseOnCallee(dummy);
-}
-
-void StackFrameDepth::enableStackLimit() {
-  // All supported platforms will currently return a non-zero estimate,
-  // except if ASan is enabled.
-  size_t stackSize = getUnderestimatedStackSize();
-  if (!stackSize) {
-    m_stackFrameLimit = getFallbackStackLimit();
-    return;
-  }
-
-  static const int kStackRoomSize = 1024;
-
-  Address stackBase = reinterpret_cast<Address>(getStackStart());
-  RELEASE_ASSERT(stackSize > static_cast<const size_t>(kStackRoomSize));
-  size_t stackRoom = stackSize - kStackRoomSize;
-  RELEASE_ASSERT(stackBase > reinterpret_cast<Address>(stackRoom));
-  m_stackFrameLimit = reinterpret_cast<uintptr_t>(stackBase - stackRoom);
-
-  // If current stack use is already exceeding estimated limit, mark as
-  // disabled.
-  if (!isSafeToRecurse())
-    disableStackLimit();
-}
-
-size_t StackFrameDepth::getUnderestimatedStackSize() {
+size_t 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)
@@ -127,14 +86,14 @@ size_t StackFrameDepth::getUnderestimatedStackSize() {
   }
   return pthread_get_stacksize_np(pthread_self());
 #elif OS(WIN) && COMPILER(MSVC)
-  return ThreadState::current()->threadStackSize();
+  return WTFThreadData::current().threadStackSize();
 #else
 #error "Stack frame size estimation not supported on this platform."
   return 0;
 #endif
 }
 
-void* StackFrameDepth::getStackStart() {
+void* getStackStart() {
 #if defined(__GLIBC__) || OS(ANDROID) || OS(FREEBSD)
   pthread_attr_t attr;
   int error;
@@ -162,7 +121,7 @@ void* StackFrameDepth::getStackStart() {
   // See https://code.google.com/p/nativeclient/issues/detail?id=3431.
   return __libc_stack_end;
 #else
-  ASSERT_NOT_REACHED();
+  NOTREACHED();
   return nullptr;
 #endif
 #elif OS(MACOSX)
@@ -181,4 +140,4 @@ void* StackFrameDepth::getStackStart() {
 #endif
 }
 
-}  // namespace blink
+}  // namespace WTF