Optimize the typeof operator.

src/compiler/js-generic-lowering.cc

Index: src/compiler/js-generic-lowering.cc
diff --git a/src/compiler/js-generic-lowering.cc b/src/compiler/js-generic-lowering.cc
index 3ebb6bc261fbec929fd2521e820a8779efb6af45..18d2e0bd9969b64f25169e9266d580b31fdcaae7 100644
--- a/src/compiler/js-generic-lowering.cc
+++ b/src/compiler/js-generic-lowering.cc
@@ -93,7 +93,6 @@ REPLACE_COMPARE_IC_CALL(JSGreaterThanOrEqual, Token::GTE)
   void JSGenericLowering::Lower##op(Node* node) { \
     ReplaceWithRuntimeCall(node, fun);            \
   }
-REPLACE_RUNTIME_CALL(JSTypeOf, Runtime::kTypeof)
 REPLACE_RUNTIME_CALL(JSCreate, Runtime::kAbort)
 REPLACE_RUNTIME_CALL(JSCreateFunctionContext, Runtime::kNewFunctionContext)
 REPLACE_RUNTIME_CALL(JSCreateWithContext, Runtime::kPushWithContext)
@@ -274,6 +273,12 @@ void JSGenericLowering::LowerJSUnaryNot(Node* node) {
 }
 
 
+void JSGenericLowering::LowerJSTypeOf(Node* node) {
+  Callable callable = CodeFactory::Typeof(isolate());
+  ReplaceWithStubCall(node, callable, CallDescriptor::kPatchableCallSite);

[Michael Starzinger, 2015/04/29 08:15:33]

As discussed offline: If the Typeof-Stub doesn't patch the call-site (the way
ICs do), we can mark this as CallDescriptor::kNoFlags instead.

[mvstanton, 2015/05/06 09:55:27]

Done.

+}
+
+
 void JSGenericLowering::LowerJSToBoolean(Node* node) {
   Callable callable =
       CodeFactory::ToBoolean(isolate(), ToBooleanStub::RESULT_AS_ODDBALL);