Set the current context to the function's context when entering to LAP.

src/x64/code-stubs-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/api-arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 2822 matching lines @@
   // isolate
   __ Move(scratch, ExternalReference::isolate_address(masm->isolate()));
   __ Push(scratch);
   // holder
   __ Push(holder);
 
   __ movp(scratch, rsp);
   // Push return address back on stack.
   __ PushReturnAddressFrom(return_address);
 
-  if (!this->is_lazy()) {
+  if (this->is_lazy()) {

[jochen (gone - plz use gerrit), 2017/03/24 15:10:15]

you could move this entire block before like 2839, then you can use "scratch"

[Yuki, 2017/03/28 14:16:58]

Done.

+    // load context from holder
+    Register temp = rax;
+    __ movp(temp, FieldOperand(holder, HeapObject::kMapOffset));
+    __ GetMapConstructor(temp, temp, context);
+    __ movp(context, FieldOperand(temp, JSFunction::kContextOffset));
+  } else {
     // load context from callee
     __ movp(context, FieldOperand(callee, JSFunction::kContextOffset));
   }
 
   // Allocate the v8::Arguments structure in the arguments' space since
   // it's not controlled by GC.
   const int kApiStackSpace = 3;
 
   PrepareCallApiFunction(masm, kApiStackSpace);
 
@@ skipping 121 matching lines @@
                            kStackUnwindSpace, nullptr, return_value_operand,
                            NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64