Revert change r12912 due to x64 perf issue

src/ia32/lithium-codegen-ia32.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 2757 matching lines @@
   Register result = ToRegister(instr->result());
   // There are two words between the frame pointer and the last argument.
   // Subtracting from length accounts for one of them add one more.
   __ sub(length, index);
   __ mov(result, Operand(arguments, length, times_4, kPointerSize));
 }
 
 
 void LCodeGen::DoLoadKeyedExternalArray(LLoadKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
-  if (ExternalArrayOpRequiresTemp<HLoadKeyed>(instr->hydrogen())) {
-    __ SmiUntag(ToRegister(instr->key()));
+  LOperand* key = instr->key();
+  if (!key->IsConstantOperand() &&
+      ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
+                                  elements_kind)) {
+    __ SmiUntag(ToRegister(key));
   }
   Operand operand(BuildFastArrayOperand(
       instr->elements(),
-      instr->key(),
+      key,
       instr->hydrogen()->key()->representation(),
       elements_kind,
       0,
       instr->additional_index()));
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
     XMMRegister result(ToDoubleRegister(instr->result()));
     __ movss(result, operand);
     __ cvtss2sd(result, result);
   } else if (elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
     __ movdbl(ToDoubleRegister(instr->result()), operand);
@@ skipping 1049 matching lines @@
     DeoptimizeIf(below_equal, instr->environment());
   } else {
     __ cmp(ToRegister(instr->index()), ToOperand(instr->length()));
     DeoptimizeIf(above_equal, instr->environment());
   }
 }
 
 
 void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
-  if (ExternalArrayOpRequiresTemp<HStoreKeyed>(instr->hydrogen())) {
-    __ SmiUntag(ToRegister(instr->key()));
+  LOperand* key = instr->key();
+  if (!key->IsConstantOperand() &&
+      ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
+                                  elements_kind)) {
+    __ SmiUntag(ToRegister(key));
   }
   Operand operand(BuildFastArrayOperand(
       instr->elements(),
-      instr->key(),
+      key,
       instr->hydrogen()->key()->representation(),
       elements_kind,
       0,
       instr->additional_index()));
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
     __ cvtsd2ss(xmm0, ToDoubleRegister(instr->value()));
     __ movss(operand, xmm0);
   } else if (elements_kind == EXTERNAL_DOUBLE_ELEMENTS) {
     __ movdbl(operand, ToDoubleRegister(instr->value()));
   } else {
@@ skipping 1706 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32