Optionally use 31-bits SMI value for 64-bit system

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 642cb272cf5fa1e2a8281ead6885ba7754fe07ad..d6d2c94216f9f6b15f0736ba3dd9cfa0e6774a72 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1884,7 +1884,8 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       } else if (val->HasRange() && val->range()->IsInSmiRange()) {
         return DefineSameAsFirst(new(zone()) LSmiTag(value));
       } else {
-        LNumberTagI* result = new(zone()) LNumberTagI(value);
+        LOperand* temp = (kSmiValueSize == 31) ? FixedTemp(xmm1) : NULL;
+        LNumberTagI* result = new(zone()) LNumberTagI(value, temp);
         return AssignEnvironment(AssignPointerMap(DefineSameAsFirst(result)));
       }
     } else if (to.IsSmi()) {
@@ -2118,9 +2119,15 @@ LInstruction* LChunkBuilder::DoLoadExternalArrayPointer(
 
 
 LInstruction* LChunkBuilder::DoLoadKeyed(HLoadKeyed* instr) {
-  ASSERT(instr->key()->representation().IsInteger32());
+  ASSERT((kSmiValueSize == 32 &&
+          instr->key()->representation().IsInteger32()) ||
+         (kSmiValueSize == 31 &&
+          instr->key()->representation().IsSmiOrInteger32()));
   ElementsKind elements_kind = instr->elements_kind();
-  LOperand* key = UseRegisterOrConstantAtStart(instr->key());
+  bool clobbers_key = instr->key()->representation().IsSmi();
+  LOperand* key = clobbers_key
+      ? UseTempRegister(instr->key())
+      : UseRegisterOrConstantAtStart(instr->key());
   LLoadKeyed* result = NULL;
 
   if (!instr->is_external()) {
@@ -2158,6 +2165,7 @@ LInstruction* LChunkBuilder::DoLoadKeyedGeneric(HLoadKeyedGeneric* instr) {
 
 LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
   ElementsKind elements_kind = instr->elements_kind();
+  bool clobbers_key = instr->key()->representation().IsSmi();
 
   if (!instr->is_external()) {
     ASSERT(instr->elements()->representation().IsTagged());
@@ -2169,7 +2177,8 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
     if (instr->value()->representation().IsDouble()) {
       object = UseRegisterAtStart(instr->elements());
       val = UseTempRegister(instr->value());
-      key = UseRegisterOrConstantAtStart(instr->key());
+      key = clobbers_key ? UseTempRegister(instr->key())
+          : UseRegisterOrConstantAtStart(instr->key());
     } else {
       ASSERT(instr->value()->representation().IsSmiOrTagged());
       object = UseTempRegister(instr->elements());
@@ -2178,7 +2187,8 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
         key = UseTempRegister(instr->key());
       } else {
         val = UseRegisterOrConstantAtStart(instr->value());
-        key = UseRegisterOrConstantAtStart(instr->key());
+        key = clobbers_key ? UseTempRegister(instr->key())
+            : UseRegisterOrConstantAtStart(instr->key());
       }
     }
 
@@ -2198,7 +2208,8 @@ LInstruction* LChunkBuilder::DoStoreKeyed(HStoreKeyed* instr) {
       elements_kind == EXTERNAL_FLOAT_ELEMENTS;
   LOperand* val = val_is_temp_register ? UseTempRegister(instr->value())
       : UseRegister(instr->value());
-  LOperand* key = UseRegisterOrConstantAtStart(instr->key());
+  LOperand* key = clobbers_key ? UseTempRegister(instr->key())
+      : UseRegisterOrConstantAtStart(instr->key());
   LOperand* external_pointer = UseRegister(instr->elements());
   return new(zone()) LStoreKeyed(external_pointer, key, val);
 }