HStoreKeyed for Smis optimized for x64 + related redundant moves of elements removed

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 41a331a07d6e663462ddf107c50b31ed2aee81b5..63888638680226214eb6cf8554b333c343c94914 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -508,6 +508,13 @@ LOperand* LChunkBuilder::UseTempRegister(HValue* value) {
 }
 
 
+LOperand* LChunkBuilder::UseTempRegisterOrConstant(HValue* value) {
+  return value->IsConstant()
+      ? chunk_->DefineConstantOperand(HConstant::cast(value))
+      : UseTempRegister(value);
+}
+
+
 LOperand* LChunkBuilder::Use(HValue* value) {
   return Use(value, new(zone()) LUnallocated(LUnallocated::NONE));
 }
@@ -2177,17 +2184,20 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
     LOperand* key = NULL;
     LOperand* val = NULL;
 
-    if (instr->value()->representation().IsDouble()) {
+    Representation value_representation = instr->value()->representation();
+    if (value_representation.IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
       val = UseTempRegister(instr->value());
       key = UseRegisterOrConstantAtStart(instr->key());
     } else {
-      ASSERT(instr->value()->representation().IsSmiOrTagged());
-      object = UseTempRegister(instr->elements());
+      ASSERT(value_representation.IsSmiOrTagged() ||
+             value_representation.IsInteger32());
       if (needs_write_barrier) {
+        object = UseTempRegister(instr->elements());
         val = UseTempRegister(instr->value());
         key = UseTempRegister(instr->key());
       } else {
+        object = UseRegisterAtStart(instr->elements());
         val = UseRegisterOrConstantAtStart(instr->value());
         key = UseRegisterOrConstantAtStart(instr->key());
       }