[turbofan] Optimize loads from the global object in JSTypeFeedbackSpecializer.

src/compiler/pipeline.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/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 524 matching lines @@
   static const char* phase_name() { return "type feedback specializing"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
     SourcePositionTable::Scope pos(data->source_positions(),
                                    SourcePosition::Unknown());
     Handle<Context> native_context(data->info()->context()->native_context());
     TypeFeedbackOracle oracle(data->isolate(), temp_zone,
                               data->info()->unoptimized_code(),
                               data->info()->feedback_vector(), native_context);
     GraphReducer graph_reducer(data->graph(), temp_zone);
-    JSTypeFeedbackSpecializer specializer(data->jsgraph(),
-                                          data->js_type_feedback(), &oracle);
+    Handle<GlobalObject> global_object = Handle<GlobalObject>::null();
+    if (data->info()->has_global_object()) {
+      global_object =
+          Handle<GlobalObject>(data->info()->global_object(), data->isolate());
+    }
+    // TODO(titzer): introduce a specialization mode/flags enum to control
+    // specializing to the global object here.
+    JSTypeFeedbackSpecializer specializer(
+        data->jsgraph(), data->js_type_feedback(), &oracle, global_object,
+        data->info()->dependencies());
     AddReducer(data, &graph_reducer, &specializer);
     graph_reducer.ReduceGraph();
   }
 };
 
 
 struct TypedLoweringPhase {
   static const char* phase_name() { return "typed lowering"; }
 
   void Run(PipelineData* data, Zone* temp_zone) {
@@ skipping 741 matching lines @@
     tcf << AsC1VRegisterAllocationData("CodeGen",
                                        data->register_allocation_data());
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8