Eliminate Smi check when changing from Smi to Integer32

src/arm/lithium-arm.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 1871 matching lines @@
   // representation change phase of Hydrogen.
   UNREACHABLE();
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   Representation from = instr->from();
   Representation to = instr->to();
   if (from.IsSmi()) {
-    if (to.IsTagged()) {
+    if (to.IsSmiOrTagged()) {
       LOperand* value = UseRegister(instr->value());
       return DefineSameAsFirst(new(zone()) LDummyUse(value));
     }
+    if (to.IsInteger32()) {
+      LOperand* value = UseRegister(instr->value());
+      return DefineSameAsFirst(new(zone()) LSmiUntag(value, false));
+    }
     from = Representation::Tagged();
   }
   if (from.IsTagged()) {
     if (to.IsDouble()) {
       info()->MarkAsDeferredCalling();
       LOperand* value = UseRegister(instr->value());
       LNumberUntagD* res = new(zone()) LNumberUntagD(value);
       return AssignEnvironment(DefineAsRegister(res));
     } else if (to.IsSmi()) {
       HValue* val = instr->value();
@@ skipping 686 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseRegister(instr->index());
   return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal