Only assign environments when they are actually needed. (ARM and ARM64 only)

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 384a21c6980dc5fce2385de50b2afeb47adb12f5..6eb5343f68666c23142f7b15431876e3a0d8cff4 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1882,29 +1882,23 @@ LInstruction* LChunkBuilder::DoForceRepresentation(HForceRepresentation* bad) {
 LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   Representation from = instr->from();
   Representation to = instr->to();
+  HValue* val = instr->value();
   if (from.IsSmi()) {
     if (to.IsTagged()) {
-      LOperand* value = UseRegister(instr->value());
+      LOperand* value = UseRegister(val);
       return DefineSameAsFirst(new(zone()) LDummyUse(value));
     }
     from = Representation::Tagged();
   }
-  // Only mark conversions that might need to allocate as calling rather than
-  // all changes. This makes simple, non-allocating conversion not have to force
-  // building a stack frame.
   if (from.IsTagged()) {
     if (to.IsDouble()) {
-      LOperand* value = UseRegister(instr->value());
-      // Temp register only necessary for minus zero check.
+      LOperand* value = UseRegister(val);
       LOperand* temp = TempRegister();
-      LInstruction* result = DefineAsRegister(
-          new(zone()) LNumberUntagD(value, temp));
-      if (!instr->value()->representation().IsSmi()) {
-        result = AssignEnvironment(result);
-      }
+      LInstruction* result =
+          DefineAsRegister(new(zone()) LNumberUntagD(value, temp));
+      if (!val->representation().IsSmi()) result = AssignEnvironment(result);
       return result;
     } else if (to.IsSmi()) {
-      HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       if (val->type().IsSmi()) {
         return DefineSameAsFirst(new(zone()) LDummyUse(value));
@@ -1912,18 +1906,18 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       return AssignEnvironment(DefineSameAsFirst(new(zone()) LCheckSmi(value)));
     } else {
       ASSERT(to.IsInteger32());
-      HValue* val = instr->value();
       if (val->type().IsSmi() || val->representation().IsSmi()) {
         LOperand* value = UseRegister(val);
         return DefineSameAsFirst(new(zone()) LSmiUntag(value, false));
       } else {
+        LOperand* value = UseRegister(val);
         bool truncating = instr->CanTruncateToInt32();
         LOperand* xmm_temp =
             (CpuFeatures::IsSafeForSnapshot(SSE2) && !truncating)
                 ? FixedTemp(xmm1) : NULL;
-        LInstruction* result = DefineSameAsFirst(
-            new(zone()) LTaggedToI(UseRegister(val), xmm_temp));
-        if (!instr->value()->representation().IsSmi()) {
+        LInstruction* result =
+            DefineSameAsFirst(new(zone()) LTaggedToI(value, xmm_temp));
+        if (!val->representation().IsSmi()) {
           // Note: Only deopts in deferred code.
           result = AssignEnvironment(result);
         }
@@ -1933,23 +1927,20 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   } else if (from.IsDouble()) {
     if (to.IsTagged()) {
       info()->MarkAsDeferredCalling();
-      LOperand* value = UseRegisterAtStart(instr->value());
+      LOperand* value = UseRegisterAtStart(val);
       LOperand* temp = FLAG_inline_new ? TempRegister() : NULL;
-
-      // Make sure that temp and result_temp are different registers.
       LUnallocated* result_temp = TempRegister();
       LNumberTagD* result = new(zone()) LNumberTagD(value, temp);
       return AssignPointerMap(Define(result, result_temp));
     } else if (to.IsSmi()) {
-      LOperand* value = UseRegister(instr->value());
+      LOperand* value = UseRegister(val);
       return AssignEnvironment(
           DefineAsRegister(new(zone()) LDoubleToSmi(value)));
     } else {
       ASSERT(to.IsInteger32());
       bool truncating = instr->CanTruncateToInt32();
       bool needs_temp = CpuFeatures::IsSafeForSnapshot(SSE2) && !truncating;
-      LOperand* value = needs_temp ?
-          UseTempRegister(instr->value()) : UseRegister(instr->value());
+      LOperand* value = needs_temp ? UseTempRegister(val) : UseRegister(val);
       LOperand* temp = needs_temp ? TempRegister() : NULL;
       LInstruction* result =
           DefineAsRegister(new(zone()) LDoubleToI(value, temp));
@@ -1959,23 +1950,23 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
   } else if (from.IsInteger32()) {
     info()->MarkAsDeferredCalling();
     if (to.IsTagged()) {
-      HValue* val = instr->value();
-      LOperand* value = UseRegister(val);
       if (!instr->CheckFlag(HValue::kCanOverflow)) {
+        LOperand* value = UseRegister(val);
         return DefineSameAsFirst(new(zone()) LSmiTag(value));
       } else if (val->CheckFlag(HInstruction::kUint32)) {
+        LOperand* value = UseRegister(val);
         LOperand* temp1 = TempRegister();
-        LOperand* temp2 = CpuFeatures::IsSupported(SSE2) ? FixedTemp(xmm1)
-                                                         : NULL;
+        LOperand* temp2 =
+            CpuFeatures::IsSupported(SSE2) ? FixedTemp(xmm1) : NULL;
         LNumberTagU* result = new(zone()) LNumberTagU(value, temp1, temp2);
         return AssignPointerMap(DefineSameAsFirst(result));
       } else {
+        LOperand* value = UseRegister(val);
         LOperand* temp = TempRegister();
         LNumberTagI* result = new(zone()) LNumberTagI(value, temp);
         return AssignPointerMap(DefineSameAsFirst(result));
       }
     } else if (to.IsSmi()) {
-      HValue* val = instr->value();
       LOperand* value = UseRegister(val);
       LInstruction* result = DefineSameAsFirst(new(zone()) LSmiTag(value));
       if (instr->CheckFlag(HValue::kCanOverflow)) {
@@ -1984,13 +1975,12 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
       return result;
     } else {
       ASSERT(to.IsDouble());
-      if (instr->value()->CheckFlag(HInstruction::kUint32)) {
+      if (val->CheckFlag(HInstruction::kUint32)) {
         LOperand* temp = FixedTemp(xmm1);
         return DefineAsRegister(
-            new(zone()) LUint32ToDouble(UseRegister(instr->value()), temp));
+            new(zone()) LUint32ToDouble(UseRegister(val), temp));
       } else {
-        return DefineAsRegister(
-            new(zone()) LInteger32ToDouble(Use(instr->value())));
+        return DefineAsRegister(new(zone()) LInteger32ToDouble(Use(val)));
       }
     }
   }