Correct handling of arrays with callbacks in the prototype chain.

src/x64/macro-assembler-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
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@@ skipping 4949 matching lines @@
   PushSafepointRegisters();
   PrepareCallCFunction(3);
   movq(arg_reg_2, object);
   movq(arg_reg_3, Immediate(object_size));
   movq(arg_reg_1, isolate, RelocInfo::EXTERNAL_REFERENCE);
   CallCFunction(
       ExternalReference::record_object_allocation_function(isolate), 3);
   PopSafepointRegisters();
 }
 
+void MacroAssembler::HasDictionaryInPrototypeChain(
+    Register object,
+    Register elements,
+    Label* found) {
+  Register temp = elements;
+  Label loop_again;
+
+  // scratch contained elements pointer.
+  movq(temp, object);
+
+  // Loop based on the map going up the prototype chain.
+  bind(&loop_again);
+  movq(temp, FieldOperand(temp, HeapObject::kMapOffset));
+  movq(kScratchRegister, FieldOperand(temp, Map::kBitField2Offset));
+  and_(kScratchRegister, Immediate(Map::kElementsKindMask));
+  shr(kScratchRegister, Immediate(Map::kElementsKindShift));
+  cmpq(kScratchRegister, Immediate(DICTIONARY_ELEMENTS));
+  j(equal, found);
+  movq(temp, FieldOperand(temp, Map::kPrototypeOffset));
+  CompareRoot(temp, Heap::kNullValueRootIndex);
+  j(not_equal, &loop_again);
+
+  // Restore elements
+  movq(elements, FieldOperand(object, JSObject::kElementsOffset));

[Michael Starzinger, 2013/11/04 15:18:17]

Instead of specializing the semantics of this function to use the elements
register, let's just pass an arbitrary "scratch" register and let the caller
take care of saving and restoring it. AFAICT "rdi" should still be available as
a true scratch register at both call-sites.

[mvstanton, 2013/11/04 16:30:05]

Thx, done.

+}
+
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64