Oilpan: handle thread-local weak tracing slightly better.

Source/platform/heap/StackFrameDepth.h

Index: Source/platform/heap/StackFrameDepth.h
diff --git a/Source/platform/heap/StackFrameDepth.h b/Source/platform/heap/StackFrameDepth.h
index 09c41a469fe4548ca13541c6833983a18734da64..66c6c0266743fa99e6e43f670b2f919b0ebdf2bf 100644
--- a/Source/platform/heap/StackFrameDepth.h
+++ b/Source/platform/heap/StackFrameDepth.h
@@ -18,7 +18,7 @@ class PLATFORM_EXPORT StackFrameDepth final {
 public:
     inline static bool isSafeToRecurse()
     {
-        ASSERT(s_stackFrameLimit);
+        ASSERT(s_stackFrameLimit || !s_isActive);
 
         // Asssume that the stack grows towards lower addresses, which
         // all the ABIs currently supported do.
@@ -31,6 +31,18 @@ public:
     static size_t getUnderestimatedStackSize();
     static void* getStackStart();
 
+    static void clearStackLimit()

[haraken, 2015/05/04 23:11:32]

configureStackLimit => enableStackLimit
clearStackLimit => disableStackLimit
m_isActive => m_enabled

?

[sof, 2015/05/06 10:39:57]

Renamed so.

+    {
+        s_stackFrameLimit = 0;
+#if ENABLE(ASSERT)
+        s_isActive = false;
+#endif
+    }
+
+#if ENABLE(ASSERT)
+    inline static bool isActive() { return s_isActive; }
+#endif
+
 #if COMPILER(MSVC)
 // Ignore C4172: returning address of local variable or temporary: dummy. This
 // warning suppression has to go outside of the function to take effect.
@@ -58,6 +70,23 @@ private:
     static const int kSafeStackFrameSize = 32 * 1024;
 
     static uintptr_t s_stackFrameLimit;
+#if ENABLE(ASSERT)
+    static bool s_isActive;
+#endif
+};
+
+class StackFrameDepthScope {

[haraken, 2015/05/04 23:11:32]

Add STACK_ALLOCATED.

[sof, 2015/05/06 10:39:57]

Not done, that would be an unnecessary restriction.

+public:
+    StackFrameDepthScope()
+    {
+        StackFrameDepth::configureStackLimit();
+        ASSERT(StackFrameDepth::isSafeToRecurse());
+    }
+
+    ~StackFrameDepthScope()
+    {
+        StackFrameDepth::clearStackLimit();
+    }
 };
 
 } // namespace blink