Eliminate Smi check when changing from Smi to Integer32

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 1911 matching lines @@
       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));
       }
       return AssignEnvironment(DefineSameAsFirst(new(zone()) LCheckSmi(value)));
     } else {
       ASSERT(to.IsInteger32());
-      if (instr->value()->type().IsSmi()) {
-        LOperand* value = UseRegister(instr->value());
+      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();
         if (CpuFeatures::IsSafeForSnapshot(SSE2)) {
-          LOperand* value = UseRegister(instr->value());
+          LOperand* value = UseRegister(val);
           LOperand* xmm_temp =
               (truncating && CpuFeatures::IsSupported(SSE3))
               ? NULL
               : FixedTemp(xmm1);
           LTaggedToI* res = new(zone()) LTaggedToI(value, xmm_temp);
           return AssignEnvironment(DefineSameAsFirst(res));
         } else {
-          LOperand* value = UseFixed(instr->value(), ecx);
+          LOperand* value = UseFixed(val, ecx);
           LTaggedToINoSSE2* res =
               new(zone()) LTaggedToINoSSE2(value, TempRegister(),
                                            TempRegister(), TempRegister());
           return AssignEnvironment(DefineFixed(res, ecx));
         }
       }
     }
   } else if (from.IsDouble()) {
     if (to.IsTagged()) {
       info()->MarkAsDeferredCalling();
@@ skipping 755 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