Inline loading of immutable properties

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 6587ce97199ca944f8daaa8938bcbf73b23f6414..1bcdcf62efdd310c03b51e12634434486903f5e9 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5600,6 +5600,29 @@ HInstruction* HOptimizedGraphBuilder::BuildMonomorphicAccess(
     BailoutId ast_id,
     BailoutId return_id,
     bool can_inline_accessor) {
+  // See if this is a load for an immutable property
+  if (info->IsLoad() && info->lookup()->IsFound() &&
+      info->lookup()->IsCacheable() && info->lookup()->IsReadOnly() &&
+      info->lookup()->IsDontDelete() && !info->map()->is_observed()) {
+    Handle<Object> value(isolate()->heap()->the_hole_value(), isolate());
+
+    if (!info->has_holder()) {
+      if (object->IsConstant() &&
+          HConstant::cast(object)->handle(isolate())->IsJSObject()) {
+        Handle<JSObject> js_object = HConstant::cast(object)->handle(isolate());
+        LookupResult lookup(isolate());
+        js_object->Lookup(*info->name(), &lookup);
+        value = handle(lookup.GetLazyValue(), isolate());
+      }
+    } else {
+      value = handle(info->lookup()->GetLazyValue(), isolate());
+    }
+
+    if (!value->IsTheHole()) {
+      AddCheckMapsUntilHolder(info->holder(), info->map(), checked_object);
+      return New<HConstant>(value);
+    }
+  }
 
   HObjectAccess access = HObjectAccess::ForMap();  // bogus default
   if (info->GetJSObjectFieldAccess(&access)) {
@@ -6791,6 +6814,22 @@ HInstruction* HGraphBuilder::BuildCheckPrototypeMaps(Handle<JSObject> prototype,
 }
 
 
+void HOptimizedGraphBuilder::AddCheckMapsUntilHolder(Handle<JSObject> holder,
+                                                     Handle<Map> receiver_map,
+                                                     HValue* checked_object) {
+  if (holder.is_null()) {
+    HInstruction::cast(checked_object)->DeleteAndReplaceWith(NULL);
+  } else {
+    Handle<JSObject> prototype(JSObject::cast(receiver_map->prototype()));
+    do {
+      if (prototype.is_identical_to(holder)) return;
+      BuildConstantMapCheck(prototype, top_info());
+      prototype = handle(JSObject::cast(prototype->GetPrototype()));
+    } while (true);
+  }
+}
+
+
 void HOptimizedGraphBuilder::AddCheckPrototypeMaps(Handle<JSObject> holder,
                                                    Handle<Map> receiver_map) {
   if (!holder.is_null()) {