Avoid recording unnecessary deoptimization environments in a couple of places.

src/ia32/lithium-ia32.cc

 // Copyright 2011 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 1029 matching lines @@
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
   return new(zone()) LGoto(instr->FirstSuccessor()->block_id());
 }
 
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
-  HValue* v = instr->value();
-  if (v->EmitAtUses()) {
-    ASSERT(v->IsConstant());
-    ASSERT(!v->representation().IsDouble());
-    HBasicBlock* successor = HConstant::cast(v)->ToBoolean()
+  HValue* value = instr->value();
+  if (value->EmitAtUses()) {
+    ASSERT(value->IsConstant());
+    ASSERT(!value->representation().IsDouble());
+    HBasicBlock* successor = HConstant::cast(value)->ToBoolean()
         ? instr->FirstSuccessor()
         : instr->SecondSuccessor();
     return new(zone()) LGoto(successor->block_id());
   }
+
+  // Untagged integers or doubles, smis and booleans don't require a
+  // deoptimization environment nor a temp register.
+  Representation rep = value->representation();
+  HType type = value->type();
+  if (!rep.IsTagged() || type.IsSmi() || type.IsBoolean()) {
+    return new(zone()) LBranch(UseRegister(value), NULL);
+  }
+
   ToBooleanStub::Types expected = instr->expected_input_types();
   // We need a temporary register when we have to access the map *or* we have
   // no type info yet, in which case we handle all cases (including the ones
   // involving maps).
   bool needs_temp = expected.NeedsMap() || expected.IsEmpty();
   LOperand* temp = needs_temp ? TempRegister() : NULL;
-  return AssignEnvironment(new(zone()) LBranch(UseRegister(v), temp));
+  return AssignEnvironment(new(zone()) LBranch(UseRegister(value), temp));
 }
 
 
 LInstruction* LChunkBuilder::DoCompareMap(HCompareMap* instr) {
   ASSERT(instr->value()->representation().IsTagged());
   LOperand* value = UseRegisterAtStart(instr->value());
   return new(zone()) LCmpMapAndBranch(value);
 }
 
 
@@ skipping 305 matching lines @@
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
     LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
     LOperand* right = UseOrConstant(instr->MostConstantOperand());
     LOperand* temp = NULL;
     if (instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
       temp = TempRegister();
     }
     LMulI* mul = new(zone()) LMulI(left, right, temp);
-    return AssignEnvironment(DefineSameAsFirst(mul));
+    if (instr->CheckFlag(HValue::kCanOverflow) ||
+        instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
+      AssignEnvironment(mul);
+    }
+    return DefineSameAsFirst(mul);
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
   } else {
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::MUL, instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoSub(HSub* instr) {
@@ skipping 207 matching lines @@
 
 LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
   LOperand* object = UseRegisterAtStart(instr->value());
   return DefineAsRegister(new(zone()) LElementsKind(object));
 }
 
 
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new(zone()) LValueOf(object, TempRegister());
-  return AssignEnvironment(DefineSameAsFirst(result));
+  return DefineSameAsFirst(result);
 }
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
   return AssignEnvironment(new(zone()) LBoundsCheck(
       UseRegisterOrConstantAtStart(instr->index()),
       UseAtStart(instr->length())));
 }
 
 
@@ skipping 319 matching lines @@
 }
 
 
 LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
     HLoadKeyedFastElement* instr) {
   ASSERT(instr->representation().IsTagged());
   ASSERT(instr->key()->representation().IsInteger32());
   LOperand* obj = UseRegisterAtStart(instr->object());
   LOperand* key = UseRegisterOrConstantAtStart(instr->key());
   LLoadKeyedFastElement* result = new(zone()) LLoadKeyedFastElement(obj, key);
-  return AssignEnvironment(DefineAsRegister(result));
+  if (instr->RequiresHoleCheck()) AssignEnvironment(result);
+  return DefineAsRegister(result);
 }
 
 
 LInstruction* LChunkBuilder::DoLoadKeyedFastDoubleElement(
     HLoadKeyedFastDoubleElement* instr) {
   ASSERT(instr->representation().IsDouble());
   ASSERT(instr->key()->representation().IsInteger32());
   LOperand* elements = UseRegisterAtStart(instr->elements());
   LOperand* key = UseRegisterOrConstantAtStart(instr->key());
   LLoadKeyedFastDoubleElement* result =
@@ skipping 404 matching lines @@
   LOperand* key = UseOrConstantAtStart(instr->key());
   LOperand* object = UseOrConstantAtStart(instr->object());
   LIn* result = new(zone()) LIn(context, key, object);
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32