Lower simplified StringAdd to stub call.

R=titzer@chromium.org
TEST=cctest/test-simplified-lowering/LowerStringOps_to_calls

Review URL: https://codereview.chromium.org/530973002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23610 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/js-typed-lowering.cc

@@ -222,7 +222,8 @@ Reduction JSTypedLowering::ReduceJSAdd(Node* node) {
   if (r.OneInputIs(Type::String())) {
     r.ConvertInputsToString();
     return r.ChangeToPureOperator(simplified()->StringAdd());
-  } else if (r.NeitherInputCanBe(Type::String())) {
+  }
+  if (r.NeitherInputCanBe(Type::String())) {
     r.ConvertInputsToNumber();
     return r.ChangeToPureOperator(simplified()->NumberAdd());
   }

src/compiler/simplified-lowering.cc

@@ -521,7 +521,7 @@ class RepresentationSelector {
       }
       case IrOpcode::kStringAdd: {
         VisitBinop(node, kMachAnyTagged, kMachAnyTagged);
-        // TODO(titzer): lower StringAdd to stub/runtime call.
+        if (lower()) lowering->DoStringAdd(node);
         break;
       }
       case IrOpcode::kLoadField: {
@@ -821,6 +821,19 @@ void SimplifiedLowering::DoStoreElement(Node* node) {
 }
 
 
+void SimplifiedLowering::DoStringAdd(Node* node) {
+  StringAddStub stub(zone()->isolate(), STRING_ADD_CHECK_NONE, NOT_TENURED);
+  CodeStubInterfaceDescriptor* d = stub.GetInterfaceDescriptor();
+  CallDescriptor::Flags flags = CallDescriptor::kNoFlags;
+  CallDescriptor* desc = Linkage::GetStubCallDescriptor(d, 0, flags, zone());
+  node->set_op(jsgraph()->common()->Call(desc));
+  node->InsertInput(zone(), 0, jsgraph()->HeapConstant(stub.GetCode()));
+  node->AppendInput(zone(), jsgraph()->UndefinedConstant());
+  node->AppendInput(zone(), graph()->start());
+  node->AppendInput(zone(), graph()->start());
+}
+
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8

src/compiler/simplified-lowering.h

@@ -27,6 +27,7 @@ class SimplifiedLowering {
   void DoStoreField(Node* node);
   void DoLoadElement(Node* node);
   void DoStoreElement(Node* node);
+  void DoStringAdd(Node* node);
 
  private:
   JSGraph* jsgraph_;

test/cctest/compiler/test-simplified-lowering.cc

@@ -1051,15 +1051,15 @@ TEST(LowerReferenceEqual_to_wordeq) {
 }
 
 
-TEST(LowerStringOps_to_rtcalls) {
-  if (false) {  // TODO(titzer): lower StringOps to runtime calls
-    TestingGraph t(Type::String(), Type::String());
+TEST(LowerStringOps_to_calls) {
+  TestingGraph t(Type::String(), Type::String());
+  if (false) {  // TODO(titzer): lower StringOps to stub/runtime calls
     t.CheckLoweringBinop(IrOpcode::kCall, t.simplified()->StringEqual());
     t.CheckLoweringBinop(IrOpcode::kCall, t.simplified()->StringLessThan());
     t.CheckLoweringBinop(IrOpcode::kCall,
                          t.simplified()->StringLessThanOrEqual());
-    t.CheckLoweringBinop(IrOpcode::kCall, t.simplified()->StringAdd());
   }
+  t.CheckLoweringBinop(IrOpcode::kCall, t.simplified()->StringAdd());
 }