Some improvements in register usage in lithium compilation of LoadKeyed/StoreKeyed operations.

src/ia32/lithium-ia32.h

 // 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 1390 matching lines @@
     return hydrogen()->is_external();
   }
 
   DECLARE_CONCRETE_INSTRUCTION(LoadKeyed, "load-keyed")
   DECLARE_HYDROGEN_ACCESSOR(LoadKeyed)
 
   uint32_t additional_index() const { return hydrogen()->index_offset(); }
 };
 
 
-inline static bool ExternalArrayOpRequiresTemp(
-    Representation key_representation,
-    ElementsKind elements_kind) {
+template <class T>
+inline static bool ExternalArrayOpRequiresTemp(T* value) {
+  CHECK(value->IsLoadKeyed() || value->IsStoreKeyed());
+  Representation key_representation = value->key()->representation();
+  ElementsKind elements_kind = value->elements_kind();
+
   // Operations that require the key to be divided by two to be converted into
   // an index cannot fold the scale operation into a load and need an extra
   // temp register to do the work.
-  return key_representation.IsTagged() &&
+  return !value->IsConstant() && key_representation.IsTagged() &&
       (elements_kind == EXTERNAL_BYTE_ELEMENTS ||
        elements_kind == EXTERNAL_UNSIGNED_BYTE_ELEMENTS ||
        elements_kind == EXTERNAL_PIXEL_ELEMENTS);
 }
 
 
 class LLoadKeyedGeneric: public LTemplateInstruction<1, 3, 0> {
  public:
   LLoadKeyedGeneric(LOperand* context, LOperand* obj, LOperand* key) {
     inputs_[0] = context;
@@ skipping 1227 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_LITHIUM_IA32_H_