Porting r9456 to x64 (Optimize KeyedStoreGeneric for Smi arrays).

src/ia32/ic-ia32.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 747 matching lines @@
   __ j(equal, &slow);
   __ CmpInstanceType(edi, JS_FUNCTION_PROXY_TYPE);
   __ j(equal, &slow);
 
   // Object case: Check key against length in the elements array.
   // eax: value
   // edx: JSObject
   // ecx: key (a smi)
   // edi: receiver map
   __ mov(ebx, FieldOperand(edx, JSObject::kElementsOffset));
-  // Check that the object is in fast mode and writable.
+  // Check array bounds. Both the key and the length of FixedArray are smis.
   __ cmp(ecx, FieldOperand(ebx, FixedArray::kLengthOffset));
   __ j(below, &fast_object_with_map_check);
 
   // Slow case: call runtime.
   __ bind(&slow);
   GenerateRuntimeSetProperty(masm, strict_mode);
 
   // Extra capacity case: Check if there is extra capacity to
   // perform the store and update the length. Used for adding one
   // element to the array by writing to array[array.length].
@@ skipping 904 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_IA32