Fix invalid usage of StoreIC_ArrayLength optimization.

src/x64/ic-x64.cc

 // Copyright 2011 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 1379 matching lines @@
 
 
 void StoreIC::GenerateArrayLength(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : name
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
   //
-  // This accepts as a receiver anything JSObject::SetElementsLength accepts
-  // (currently anything except for external and pixel arrays which means
-  // anything with elements of FixedArray type.), but currently is restricted
-  // to JSArray.
-  // Value must be a number, but only smis are accepted as the most common case.
+  // This accepts as a receiver anything JSArray::SetElementsLength accepts
+  // (currently anything except for external arrays which means anything with
+  // elements of FixedArray type).  Value must be a number, but only smis are
+  // accepted as the most common case.
 
   Label miss;
 
   Register receiver = rdx;
   Register value = rax;
   Register scratch = rbx;
 
   // Check that the receiver isn't a smi.
   __ JumpIfSmi(receiver, &miss);
 
   // Check that the object is a JS array.
   __ CmpObjectType(receiver, JS_ARRAY_TYPE, scratch);
   __ j(not_equal, &miss);
 
   // Check that elements are FixedArray.
   // We rely on StoreIC_ArrayLength below to deal with all types of
   // fast elements (including COW).
   __ movq(scratch, FieldOperand(receiver, JSArray::kElementsOffset));
   __ CmpObjectType(scratch, FIXED_ARRAY_TYPE, scratch);
   __ j(not_equal, &miss);
 
+  // Check that the array has fast properties, otherwise the length
+  // property might have been redefined.
+  __ movq(scratch, FieldOperand(receiver, JSArray::kPropertiesOffset));
+  __ CompareRoot(FieldOperand(scratch, FixedArray::kMapOffset),
+                 Heap::kHashTableMapRootIndex);
+  __ j(equal, &miss);
+
   // Check that value is a smi.
   __ JumpIfNotSmi(value, &miss);
 
   // Prepare tail call to StoreIC_ArrayLength.
   __ pop(scratch);
   __ push(receiver);
   __ push(value);
   __ push(scratch);  // return address
 
   ExternalReference ref =
@@ skipping 256 matching lines @@
   Condition cc = *jmp_address == Assembler::kJncShortOpcode
       ? not_zero
       : zero;
   *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64