Fix the context check in LoadGlobalFunctionPrototype

src/x64/stub-cache-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 227 matching lines @@
   __ movp(prototype, FieldOperand(prototype, Map::kPrototypeOffset));
 }
 
 
 void StubCompiler::GenerateDirectLoadGlobalFunctionPrototype(
     MacroAssembler* masm,
     int index,
     Register prototype,
     Label* miss) {
   Isolate* isolate = masm->isolate();
-  // Check we're still in the same context.
-  __ Move(prototype, isolate->global_object());
-  __ cmpq(Operand(rsi, Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX)),
-          prototype);
-  __ j(not_equal, miss);
   // Get the global function with the given index.
   Handle<JSFunction> function(
       JSFunction::cast(isolate->native_context()->get(index)));
+
+  // Check we're still in the same context.
+  Register scratch = prototype;
+  const int offset = Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX);
+  __ movp(scratch, Operand(rsi, offset));
+  __ movp(scratch, FieldOperand(scratch, GlobalObject::kNativeContextOffset));
+  __ Cmp(Operand(scratch, Context::SlotOffset(index)), function);
+  __ j(not_equal, miss);
+
   // Load its initial map. The global functions all have initial maps.
   __ Move(prototype, Handle<Map>(function->initial_map()));
   // Load the prototype from the initial map.
   __ movp(prototype, FieldOperand(prototype, Map::kPrototypeOffset));
 }
 
 
 void StubCompiler::GenerateLoadArrayLength(MacroAssembler* masm,
                                            Register receiver,
                                            Register scratch,
@@ skipping 1588 matching lines @@
   // -----------------------------------
   TailCallBuiltin(masm, Builtins::kKeyedLoadIC_Miss);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64