MIPS: Improve register allocation for Lithium representation changes on ARM

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index fb4e6153471d65f198123567babf5c90889d16c6..0a220989c8cbe00d7fda05fead0403ea10d6f573 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1628,11 +1628,11 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       return AssignEnvironment(DefineAsRegister(res));
     } else {
       ASSERT(to.IsInteger32());
-      LOperand* value = UseRegister(instr->value());
+      LOperand* value = UseRegisterAtStart(instr->value());
       bool needs_check = !instr->value()->type().IsSmi();
       LInstruction* res = NULL;
       if (!needs_check) {
-        res = DefineSameAsFirst(new LSmiUntag(value, needs_check));
+        res = DefineAsRegister(new LSmiUntag(value, needs_check));
       } else {
         LOperand* temp1 = TempRegister();
         LOperand* temp2 = instr->CanTruncateToInt32() ? TempRegister()
@@ -1668,12 +1668,12 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   } else if (from.IsInteger32()) {
     if (to.IsTagged()) {
       HValue* val = instr->value();
-      LOperand* value = UseRegister(val);
+      LOperand* value = UseRegisterAtStart(val);
       if (val->HasRange() && val->range()->IsInSmiRange()) {
-        return DefineSameAsFirst(new LSmiTag(value));
+        return DefineAsRegister(new LSmiTag(value));
       } else {
         LNumberTagI* result = new LNumberTagI(value);
-        return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
+        return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
       }
     } else {
       ASSERT(to.IsDouble());