From: verwaest@chromium.org <verwaest@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Tue, 16 Jul 2013 14:01:46 +0000 (+0000)
Subject: Try to remove invalidated stubs before falling back to checking the constant state.
X-Git-Tag: upstream/4.7.83~13356
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f24a5d32009dfb170724734b8e6bce9c7fab3675;p=platform%2Fupstream%2Fv8.git

Try to remove invalidated stubs before falling back to checking the constant state.

BUG=chromium:260585
R=hpayer@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19267019

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15693 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---

diff --git a/src/ic.cc b/src/ic.cc
index 2f63fee..e09d83e 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -191,17 +191,6 @@ static bool TryRemoveInvalidPrototypeDependentStub(Code* target,
     if (Name::cast(name) != stub_name) return false;
   }
 
-  if (receiver->IsGlobalObject()) {
-    if (!name->IsName()) return false;
-    Isolate* isolate = target->GetIsolate();
-    LookupResult lookup(isolate);
-    GlobalObject* global = GlobalObject::cast(receiver);
-    global->LocalLookupRealNamedProperty(Name::cast(name), &lookup);
-    if (!lookup.IsFound()) return false;
-    PropertyCell* cell = global->GetPropertyCell(&lookup);
-    return cell->type()->IsConstant();
-  }
-
   InlineCacheHolderFlag cache_holder =
       Code::ExtractCacheHolderFromFlags(target->flags());
 
@@ -242,18 +231,32 @@ static bool TryRemoveInvalidPrototypeDependentStub(Code* target,
     return true;
   }
 
+  // The stub is not in the cache. We've ruled out all other kinds of failure
+  // except for proptotype chain changes, a deprecated map, a map that's
+  // different from the one that the stub expects, or a constant global property
+  // that will become mutable. Threat all those situations as prototype failures
+  // (stay monomorphic if possible).
+
   // If the IC is shared between multiple receivers (slow dictionary mode), then
   // the map cannot be deprecated and the stub invalidated.
-  if (cache_holder != OWN_MAP) return false;
+  if (cache_holder == OWN_MAP) {
+    Map* old_map = target->FindFirstMap();
+    if (old_map == map) return true;
+    if (old_map != NULL && old_map->is_deprecated()) return true;
+  }
 
-  // The stub is not in the cache. We've ruled out all other kinds of failure
-  // except for proptotype chain changes, a deprecated map, or a map that's
-  // different from the one that the stub expects. If the map hasn't changed,
-  // assume it's a prototype failure. Treat deprecated maps in the same way as
-  // prototype failures (stay monomorphic if possible).
-  Map* old_map = target->FindFirstMap();
-  if (old_map == NULL) return false;
-  return old_map == map || old_map->is_deprecated();
+  if (receiver->IsGlobalObject()) {
+    if (!name->IsName()) return false;
+    Isolate* isolate = target->GetIsolate();
+    LookupResult lookup(isolate);
+    GlobalObject* global = GlobalObject::cast(receiver);
+    global->LocalLookupRealNamedProperty(Name::cast(name), &lookup);
+    if (!lookup.IsFound()) return false;
+    PropertyCell* cell = global->GetPropertyCell(&lookup);
+    return cell->type()->IsConstant();
+  }
+
+  return false;
 }