Eliminate Smi check when changing from Smi to Integer32

BUG=
R=verwaest@chromium.org

Review URL: https://chromiumcodereview.appspot.com/22824003

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16362 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-arm.cc

@@ -1925,11 +1925,12 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       ASSERT(to.IsInteger32());
       LOperand* value = NULL;
       LInstruction* res = NULL;
-      if (instr->value()->type().IsSmi()) {
-        value = UseRegisterAtStart(instr->value());
+      HValue* val = instr->value();
+      if (val->type().IsSmi() || val->representation().IsSmi()) {
+        value = UseRegisterAtStart(val);
         res = DefineAsRegister(new(zone()) LSmiUntag(value, false));
       } else {
-        value = UseRegister(instr->value());
+        value = UseRegister(val);
         LOperand* temp1 = TempRegister();
         LOperand* temp2 = FixedTemp(d11);
         res = DefineSameAsFirst(new(zone()) LTaggedToI(value,

src/ia32/lithium-ia32.cc

@@ -1945,13 +1945,14 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       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
@@ -1959,7 +1960,7 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
           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());

src/x64/lithium-x64.cc

@@ -1843,8 +1843,9 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       return AssignEnvironment(DefineSameAsFirst(new(zone()) LCheckSmi(value)));
     } else {
       ASSERT(to.IsInteger32());
-      LOperand* value = UseRegister(instr->value());
-      if (instr->value()->type().IsSmi()) {
+      HValue* val = instr->value();
+      LOperand* value = UseRegister(val);
+      if (val->type().IsSmi() || val->representation().IsSmi()) {
         return DefineSameAsFirst(new(zone()) LSmiUntag(value, false));
       } else {
         bool truncating = instr->CanTruncateToInt32();