Add a flag to print the time it takes to compile HydrogenCodeStubs.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 2700dbbe9c505c4e42a667695fe5ea409646c9d9..64a6dedd3257df56fda75c2d10a4a2239e706176 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -301,9 +301,18 @@ static Handle<Code> DoGenerateCode(Isolate* isolate, Stub* stub) {
     ASSERT(descriptor->stack_parameter_count_ == NULL);
     return stub->GenerateLightweightMissCode(isolate);
   }
+  ElapsedTimer timer;
+  if (FLAG_profile_hydrogen_code_stub_compilation) {
+    timer.Start();

[Yang, 2013/10/02 09:53:53]

You don't want to include GenerateLightweightMissCode?

+  }
   CodeStubGraphBuilder<Stub> builder(isolate, stub);
   LChunk* chunk = OptimizeGraph(builder.CreateGraph());
-  return chunk->Codegen();
+  Handle<Code> code = chunk->Codegen();
+  if (FLAG_profile_hydrogen_code_stub_compilation) {
+    double ms = timer.Elapsed().InMillisecondsF();
+    PrintF("[Lazy compilation of %s took %0.3f ms]\n", *stub->GetName(), ms);
+  }
+  return code;
 }