Make state stack thread local. When using Lockers the state stacks of...

src/top.h

Index: src/top.h
===================================================================
--- src/top.h	(revision 5653)
+++ src/top.h	(working copy)
@@ -41,6 +41,7 @@
 
 class SaveContext;  // Forward declaration.
 class ThreadVisitor;  // Defined in v8threads.h
+class VMState;  // Defined in vm-state.h
 
 class ThreadLocalTop BASE_EMBEDDED {
  public:
@@ -101,10 +102,15 @@
   // Stack.
   Address c_entry_fp_;  // the frame pointer of the top c entry frame
   Address handler_;   // try-blocks are chained through the stack
+
 #ifdef ENABLE_LOGGING_AND_PROFILING
   Address js_entry_sp_;  // the stack pointer of the bottom js entry frame
 #endif
 
+#ifdef ENABLE_VMSTATE_TRACKING
+  VMState* current_vm_state_;
+#endif
+
   // Generated code scratch locations.
   int32_t formal_count_;
 
@@ -254,6 +260,16 @@
   }
 #endif
 
+#ifdef ENABLE_VMSTATE_TRACKING
+  static VMState* current_vm_state() {
+    return thread_local_.current_vm_state_;
+  }
+
+  static void set_current_vm_state(VMState* state) {
+    thread_local_.current_vm_state_ = state;
+  }
+#endif
+
   // Generated code scratch locations.
   static void* formal_count_address() { return &thread_local_.formal_count_; }