Lower simplified StringAdd to stub call.

src/compiler/simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/simplified-lowering.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/compiler/representation-change.h"
@@ skipping 489 matching lines @@
         // TODO(titzer): lower StringLessThan to stub/runtime call.
         break;
       }
       case IrOpcode::kStringLessThanOrEqual: {
         VisitBinop(node, kMachAnyTagged, kRepBit);
         // TODO(titzer): lower StringLessThanOrEqual to stub/runtime call.
         break;
       }
       case IrOpcode::kStringAdd: {
         VisitBinop(node, kMachAnyTagged, kMachAnyTagged);
-        // TODO(titzer): lower StringAdd to stub/runtime call.
+        if (lower()) lowering->DoStringAdd(node);
         break;
       }
       case IrOpcode::kLoadField: {
         FieldAccess access = FieldAccessOf(node->op());
         ProcessInput(node, 0, changer_->TypeForBasePointer(access));
         SetOutput(node, access.machine_type);
         if (lower()) lowering->DoLoadField(node);
         break;
       }
       case IrOpcode::kStoreField: {
@@ skipping 279 matching lines @@
 
 void SimplifiedLowering::DoStoreElement(Node* node) {
   const ElementAccess& access = ElementAccessOf(node->op());
   WriteBarrierKind kind = ComputeWriteBarrierKind(
       access.base_is_tagged, access.machine_type, access.type);
   node->set_op(machine_.Store(access.machine_type, kind));
   node->ReplaceInput(1, ComputeIndex(access, node->InputAt(1)));
 }
 
 
+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