introduce LTaggedToSmi

src/ia32/lithium-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 1787 matching lines @@
       LOperand* value = UseRegister(instr->value());
       // Temp register only necessary for minus zero check.
       LOperand* temp = TempRegister();
       LNumberUntagD* res = new(zone()) LNumberUntagD(value, temp);
       return AssignEnvironment(DefineAsRegister(res));
     } else if (to.IsSmi()) {
       HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->type().IsSmi()) {
         return DefineSameAsFirst(new(zone()) LDummyUse(value));
+      } else {
+        bool truncating = instr->CanTruncateToSmi();
+        LOperand* temp =
+            (CpuFeatures::IsSafeForSnapshot(SSE2) && !truncating)
+                ? FixedTemp(xmm1) : NULL;
+        LTaggedToSmi* res = new(zone()) LTaggedToSmi(UseRegister(val), temp);
+
+        return AssignEnvironment(DefineSameAsFirst(res));
       }
-      return AssignEnvironment(DefineSameAsFirst(new(zone()) LCheckSmi(value)));
     } else {
       ASSERT(to.IsInteger32());
       HValue* val = instr->value();
       if (val->type().IsSmi() || val->representation().IsSmi()) {
         LOperand* value = UseRegister(val);
         return DefineSameAsFirst(new(zone()) LSmiUntag(value, false));
       } else {
         bool truncating = instr->CanTruncateToInt32();
         LOperand* xmm_temp =
             (CpuFeatures::IsSafeForSnapshot(SSE2) && !truncating)
@@ skipping 762 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32