Inline number to string conversion for string addition into BinaryOp(Stub).

This fixes a performance regression that was caused by converting the
BinaryOpStub to a Hydrogen code stub. It also fixes a leftover TODO wrt.
the handling of Number*String or String*Number versions of the stub.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/27674002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17290 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -65,7 +65,8 @@ void NumberToStringStub::InitializeInterfaceDescriptor(
   static Register registers[] = { r0 };
   descriptor->register_param_count_ = 1;
   descriptor->register_params_ = registers;
-  descriptor->deoptimization_handler_ = NULL;
+  descriptor->deoptimization_handler_ =
+      Runtime::FunctionForId(Runtime::kNumberToString)->entry;
 }
 
 

src/code-stubs-hydrogen.cc

@@ -351,7 +351,7 @@ template <>
 HValue* CodeStubGraphBuilder<NumberToStringStub>::BuildCodeStub() {
   info()->MarkAsSavesCallerDoubles();
   HValue* number = GetParameter(NumberToStringStub::kNumber);
-  return BuildNumberToString(number);
+  return BuildNumberToString(number, handle(Type::Number(), isolate()));
 }
 
 
@@ -881,35 +881,52 @@ HValue* CodeStubGraphBuilder<BinaryOpStub>::BuildCodeInitializedStub() {
   if (stub->operation() == Token::ADD &&
       (left_type->Maybe(Type::String()) || right_type->Maybe(Type::String())) &&
       !left_type->Is(Type::String()) && !right_type->Is(Type::String())) {
-    // For the generic add stub a fast case for String add is performance
+    // For the generic add stub a fast case for string addition is performance
     // critical.
     if (left_type->Maybe(Type::String())) {
-      IfBuilder left_string(this);
-      left_string.If<HIsStringAndBranch>(left);
-      left_string.Then();
-      Push(Add<HStringAdd>(left, right, STRING_ADD_CHECK_RIGHT));
-      left_string.Else();
-      Push(AddInstruction(BuildBinaryOperation(stub->operation(),
-          left, right, left_type, right_type, result_type,
-          stub->fixed_right_arg(), true)));
-      left_string.End();
+      IfBuilder if_leftisstring(this);
+      if_leftisstring.If<HIsStringAndBranch>(left);
+      if_leftisstring.Then();
+      {
+        Push(AddInstruction(BuildBinaryOperation(
+                    stub->operation(), left, right,
+                    handle(Type::String(), isolate()), right_type,
+                    result_type, stub->fixed_right_arg(), true)));
+      }
+      if_leftisstring.Else();
+      {
+        Push(AddInstruction(BuildBinaryOperation(
+                    stub->operation(), left, right,
+                    left_type, right_type, result_type,
+                    stub->fixed_right_arg(), true)));
+      }
+      if_leftisstring.End();
       result = Pop();
     } else {
-      IfBuilder right_string(this);
-      right_string.If<HIsStringAndBranch>(right);
-      right_string.Then();
-      Push(Add<HStringAdd>(left, right, STRING_ADD_CHECK_LEFT));
-      right_string.Else();
-      Push(AddInstruction(BuildBinaryOperation(stub->operation(),
-          left, right, left_type, right_type, result_type,
-          stub->fixed_right_arg(), true)));
-      right_string.End();
+      IfBuilder if_rightisstring(this);
+      if_rightisstring.If<HIsStringAndBranch>(right);
+      if_rightisstring.Then();
+      {
+        Push(AddInstruction(BuildBinaryOperation(
+                    stub->operation(), left, right,
+                    left_type, handle(Type::String(), isolate()),
+                    result_type, stub->fixed_right_arg(), true)));
+      }
+      if_rightisstring.Else();
+      {
+        Push(AddInstruction(BuildBinaryOperation(
+                    stub->operation(), left, right,
+                    left_type, right_type, result_type,
+                    stub->fixed_right_arg(), true)));
+      }
+      if_rightisstring.End();
       result = Pop();
     }
   } else {
-    result = AddInstruction(BuildBinaryOperation(stub->operation(),
-        left, right, left_type, right_type, result_type,
-        stub->fixed_right_arg(), true));
+    result = AddInstruction(BuildBinaryOperation(
+            stub->operation(), left, right,
+            left_type, right_type, result_type,
+            stub->fixed_right_arg(), true));
   }
 
   // If we encounter a generic argument, the number conversion is

src/code-stubs.cc

@@ -570,14 +570,8 @@ void BinaryOpStub::UpdateStatus(Handle<Object> left,
 
   State max_input = Max(left_state_, right_state_);
 
-  // TODO(olivf) Instead of doing this normalization we should have a Hydrogen
-  // version of the LookupNumberStringCache to avoid a converting StringAddStub.
-  if (left_state_ == STRING && right_state_ < STRING) {
-    right_state_ = GENERIC;
-  } else if (right_state_ == STRING && left_state_ < STRING) {
-    left_state_ = GENERIC;
-  } else if (!has_int_result() && op_ != Token::SHR &&
-             max_input <= NUMBER && max_input > result_state_) {
+  if (!has_int_result() && op_ != Token::SHR &&
+      max_input <= NUMBER && max_input > result_state_) {
     result_state_ = max_input;
   }
 
@@ -1127,6 +1121,12 @@ void ArrayConstructorStubBase::InstallDescriptors(Isolate* isolate) {
 }
 
 
+void NumberToStringStub::InstallDescriptors(Isolate* isolate) {
+  NumberToStringStub stub;
+  InstallDescriptor(isolate, &stub);
+}
+
+
 void FastNewClosureStub::InstallDescriptors(Isolate* isolate) {
   FastNewClosureStub stub(STRICT_MODE, false);
   InstallDescriptor(isolate, &stub);

src/code-stubs.h

@@ -477,6 +477,8 @@ class NumberToStringStub V8_FINAL : public HydrogenCodeStub {
       Isolate* isolate,
       CodeStubInterfaceDescriptor* descriptor) V8_OVERRIDE;
 
+  static void InstallDescriptors(Isolate* isolate);
+
   // Parameters accessed via CodeStubGraphBuilder::GetParameter()
   static const int kNumber = 0;
 

src/hydrogen.h

@@ -1234,14 +1234,7 @@ class HGraphBuilder {
                                    ElementsKind to_kind,
                                    bool is_jsarray);
 
-  // Do lookup in the number string cache. If the object is not found
-  // in the cache, the false branch of the continuation is taken;
-  // otherwise the true branch is taken and the returned value contains
-  // the cache value for the object. The returned value must NOT be used
-  // on the false branch.
-  HValue* BuildLookupNumberStringCache(HValue* object,
-                                       HIfContinuation* continuation);
-  HValue* BuildNumberToString(HValue* number);
+  HValue* BuildNumberToString(HValue* object, Handle<Type> type);
 
   HInstruction* BuildUncheckedMonomorphicElementAccess(
       HValue* checked_object,

src/ia32/code-stubs-ia32.cc

@@ -70,7 +70,8 @@ void NumberToStringStub::InitializeInterfaceDescriptor(
   static Register registers[] = { eax };
   descriptor->register_param_count_ = 1;
   descriptor->register_params_ = registers;
-  descriptor->deoptimization_handler_ = NULL;
+  descriptor->deoptimization_handler_ =
+      Runtime::FunctionForId(Runtime::kNumberToString)->entry;
 }
 
 

src/isolate.cc

@@ -2327,6 +2327,7 @@ bool Isolate::Init(Deserializer* des) {
     ArrayConstructorStubBase::InstallDescriptors(this);
     InternalArrayConstructorStubBase::InstallDescriptors(this);
     FastNewClosureStub::InstallDescriptors(this);
+    NumberToStringStub::InstallDescriptors(this);
   }
 
   if (FLAG_sweeper_threads > 0) {

src/x64/code-stubs-x64.cc

@@ -66,7 +66,8 @@ void NumberToStringStub::InitializeInterfaceDescriptor(
   static Register registers[] = { rax };
   descriptor->register_param_count_ = 1;
   descriptor->register_params_ = registers;
-  descriptor->deoptimization_handler_ = NULL;
+  descriptor->deoptimization_handler_ =
+      Runtime::FunctionForId(Runtime::kNumberToString)->entry;
 }