Avoid recording unnecessary deoptimization environments in a couple of places.

This reduces the number of uses and potentially shortens live ranges.
Review URL: http://codereview.chromium.org/8983018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10370 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-arm.cc

@@ -1038,14 +1038,23 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
-  HValue* v = instr->value();
-  if (v->EmitAtUses()) {
-    HBasicBlock* successor = HConstant::cast(v)->ToBoolean()
+  HValue* value = instr->value();
+  if (value->EmitAtUses()) {
+    HBasicBlock* successor = HConstant::cast(value)->ToBoolean()
         ? instr->FirstSuccessor()
         : instr->SecondSuccessor();
     return new LGoto(successor->block_id());
   }
-  return AssignEnvironment(new LBranch(UseRegister(v)));
+
+  LBranch* result = new LBranch(UseRegister(value));
+  // Tagged values that are not known smis or booleans require a
+  // deoptimization environment.
+  Representation rep = value->representation();
+  HType type = value->type();
+  if (rep.IsTagged() && !type.IsSmi() && !type.IsBoolean()) {
+    return AssignEnvironment(result);
+  }
+  return result;
 }
 
 
@@ -1344,7 +1353,12 @@ LInstruction* LChunkBuilder::DoMul(HMul* instr) {
     } else {
       left = UseRegisterAtStart(instr->LeastConstantOperand());
     }
-    return AssignEnvironment(DefineAsRegister(new LMulI(left, right, temp)));
+    LMulI* mul = new LMulI(left, right, temp);
+    if (instr->CheckFlag(HValue::kCanOverflow) ||
+        instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
+      AssignEnvironment(mul);
+    }
+    return DefineAsRegister(mul);
 
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
@@ -1556,7 +1570,7 @@ LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new LValueOf(object, TempRegister());
-  return AssignEnvironment(DefineAsRegister(result));
+  return DefineAsRegister(result);
 }
 
 
@@ -1874,7 +1888,8 @@ LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
   LOperand* obj = UseRegisterAtStart(instr->object());
   LOperand* key = UseRegisterAtStart(instr->key());
   LLoadKeyedFastElement* result = new LLoadKeyedFastElement(obj, key);
-  return AssignEnvironment(DefineAsRegister(result));
+  if (instr->RequiresHoleCheck()) AssignEnvironment(result);
+  return DefineAsRegister(result);
 }
 
 

src/ia32/lithium-ia32.cc

@@ -1047,22 +1047,31 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 
 
 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));
 }
 
 
@@ -1388,7 +1397,11 @@ LInstruction* LChunkBuilder::DoMul(HMul* instr) {
       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 {
@@ -1616,7 +1629,7 @@ LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new(zone()) LValueOf(object, TempRegister());
-  return AssignEnvironment(DefineSameAsFirst(result));
+  return DefineSameAsFirst(result);
 }
 
 
@@ -1956,7 +1969,8 @@ LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
   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);
 }
 
 

src/mips/lithium-mips.cc

@@ -1038,14 +1038,23 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 
 
 LInstruction* LChunkBuilder::DoBranch(HBranch* instr) {
-  HValue* v = instr->value();
-  if (v->EmitAtUses()) {
-    HBasicBlock* successor = HConstant::cast(v)->ToBoolean()
+  HValue* value = instr->value();
+  if (value->EmitAtUses()) {
+    HBasicBlock* successor = HConstant::cast(value)->ToBoolean()
         ? instr->FirstSuccessor()
         : instr->SecondSuccessor();
     return new LGoto(successor->block_id());
   }
-  return AssignEnvironment(new LBranch(UseRegister(v)));
+
+  LBranch* result = new LBranch(UseRegister(value));
+  // Tagged values that are not known smis or booleans require a
+  // deoptimization environment.
+  Representation rep = value->representation();
+  HType type = value->type();
+  if (rep.IsTagged() && !type.IsSmi() && !type.IsBoolean()) {
+    return AssignEnvironment(result);
+  }
+  return result;
 }
 
 
@@ -1345,7 +1354,12 @@ LInstruction* LChunkBuilder::DoMul(HMul* instr) {
     } else {
       left = UseRegisterAtStart(instr->LeastConstantOperand());
     }
-    return AssignEnvironment(DefineAsRegister(new LMulI(left, right, temp)));
+    LMulI* mul = new LMulI(left, right, temp);
+    if (instr->CheckFlag(HValue::kCanOverflow) ||
+        instr->CheckFlag(HValue::kBailoutOnMinusZero)) {
+      AssignEnvironment(mul);
+    }
+    return DefineAsRegister(mul);
 
   } else if (instr->representation().IsDouble()) {
     return DoArithmeticD(Token::MUL, instr);
@@ -1558,7 +1572,7 @@ LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new LValueOf(object, TempRegister());
-  return AssignEnvironment(DefineAsRegister(result));
+  return DefineAsRegister(result);
 }
 
 
@@ -1877,7 +1891,8 @@ LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
   LOperand* obj = UseRegisterAtStart(instr->object());
   LOperand* key = UseRegisterAtStart(instr->key());
   LLoadKeyedFastElement* result = new LLoadKeyedFastElement(obj, key);
-  return AssignEnvironment(DefineAsRegister(result));
+  if (instr->RequiresHoleCheck()) AssignEnvironment(result);
+  return DefineAsRegister(result);
 }
 
 

src/runtime.cc

@@ -431,7 +431,6 @@ static Handle<Object> CreateObjectLiteralBoilerplate(
 static const int kSmiOnlyLiteralMinimumLength = 1024;
 
 
-// static
 Handle<Object> Runtime::CreateArrayLiteralBoilerplate(
     Isolate* isolate,
     Handle<FixedArray> literals,

src/x64/lithium-x64.cc

@@ -1033,16 +1033,25 @@ LInstruction* LChunkBuilder::DoGoto(HGoto* instr) {
 
 
 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 LGoto(successor->block_id());
   }
-  return AssignEnvironment(new LBranch(UseRegister(v)));
+
+  LBranch* result = new LBranch(UseRegister(value));
+  // Tagged values that are not known smis or booleans require a
+  // deoptimization environment.
+  Representation rep = value->representation();
+  HType type = value->type();
+  if (rep.IsTagged() && !type.IsSmi() && !type.IsBoolean()) {
+    return AssignEnvironment(result);
+  }
+  return result;
 }
 
 
@@ -1329,7 +1338,11 @@ LInstruction* LChunkBuilder::DoMul(HMul* instr) {
     LOperand* left = UseRegisterAtStart(instr->LeastConstantOperand());
     LOperand* right = UseOrConstant(instr->MostConstantOperand());
     LMulI* mul = new LMulI(left, right);
-    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 {
@@ -1553,7 +1566,7 @@ LInstruction* LChunkBuilder::DoElementsKind(HElementsKind* instr) {
 LInstruction* LChunkBuilder::DoValueOf(HValueOf* instr) {
   LOperand* object = UseRegister(instr->value());
   LValueOf* result = new LValueOf(object);
-  return AssignEnvironment(DefineSameAsFirst(result));
+  return DefineSameAsFirst(result);
 }
 
 
@@ -1866,7 +1879,8 @@ LInstruction* LChunkBuilder::DoLoadKeyedFastElement(
   LOperand* obj = UseRegisterAtStart(instr->object());
   LOperand* key = UseRegisterOrConstantAtStart(instr->key());
   LLoadKeyedFastElement* result = new LLoadKeyedFastElement(obj, key);
-  return AssignEnvironment(DefineAsRegister(result));
+  if (instr->RequiresHoleCheck()) AssignEnvironment(result);
+  return DefineAsRegister(result);
 }