Inline immutable property loads

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5325 matching lines @@
 HCheckMaps* HOptimizedGraphBuilder::AddCheckMap(HValue* object,
                                                 Handle<Map> map) {
   BuildCheckHeapObject(object);
   return Add<HCheckMaps>(object, map, top_info());
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildLoadNamedField(
     PropertyAccessInfo* info,
     HValue* checked_object) {
+  // See if this is a load for an immutable property
+  if (checked_object->ActualValue()->IsConstant() &&
+      info->lookup()->IsCacheable() &&
+      info->lookup()->IsReadOnly() && info->lookup()->IsDontDelete()) {
+    Handle<Object> object(
+        HConstant::cast(checked_object->ActualValue())->handle(isolate()));
+
+    if (object->IsJSObject()) {
+      Handle<Object> value(isolate()->heap()->the_hole_value(), isolate());

[Toon Verwaest, 2014/04/10 11:58:31]

Why do you pre-declare value to the hole rather than just doing Handle<Object>
value(lookup.GetLazyValue(), isolate()) ?

[p.antonov, 2014/04/11 12:09:37]

Done.

+      LookupResult lookup(isolate());
+      Handle<JSObject>::cast(object)->Lookup(*info->name(), &lookup);
+      value = handle(lookup.GetLazyValue(), isolate());
+
+      if (!value->IsTheHole()) {
+        return New<HConstant>(value);
+      }
+    }
+  }
+
   HObjectAccess access = info->access();
   if (access.representation().IsDouble()) {
     // Load the heap number.
     checked_object = Add<HLoadNamedField>(
         checked_object, static_cast<HValue*>(NULL),
         access.WithRepresentation(Representation::Tagged()));
     checked_object->set_type(HType::HeapNumber());
     // Load the double value from it.
     access = HObjectAccess::ForHeapNumberValue();
   }
@@ skipping 6184 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal