Add initial hydrogenized NewStringAddStub.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 44b952cfa702bbbb4030036695c32c25bf1e1b99..1e86453d62421984ab2920cf36cb39d5a650d833 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -4566,6 +4566,10 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
       } else {
         __ mov(operand, value);
       }
+    } else if (representation.IsInteger32()) {
+      Immediate immediate = ToImmediate(operand_value, representation);
+      ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
+      __ mov(operand, immediate);
     } else {
       Handle<Object> handle_value = ToHandle(operand_value);
       ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
@@ -5015,10 +5019,18 @@ void LCodeGen::DoDeferredStringCharFromCode(LStringCharFromCode* instr) {
 
 
 void LCodeGen::DoStringAdd(LStringAdd* instr) {
-  EmitPushTaggedOperand(instr->left());
-  EmitPushTaggedOperand(instr->right());
-  StringAddStub stub(instr->hydrogen()->flags());
-  CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
+  if (FLAG_new_string_add) {
+    ASSERT(ToRegister(instr->left()).is(edx));
+    ASSERT(ToRegister(instr->right()).is(eax));
+    NewStringAddStub stub(instr->hydrogen()->flags(),
+                          isolate()->heap()->GetPretenureMode());
+    CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
+  } else {
+    EmitPushTaggedOperand(instr->left());
+    EmitPushTaggedOperand(instr->right());
+    StringAddStub stub(instr->hydrogen()->flags());
+    CallCode(stub.GetCode(isolate()), RelocInfo::CODE_TARGET, instr);
+  }
 }