Handle accessors on the prototype chain in StoreICs.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 1f0070b193dff8b232a3020a1cd72654e44d3bea..e3663c0b5ff8e443a667c3d85b98d6d7647eaa1e 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1315,7 +1315,15 @@ static bool LookupForWrite(Handle<JSObject> receiver,
                            LookupResult* lookup) {
   receiver->LocalLookup(*name, lookup);
   if (!StoreICableLookup(lookup)) {
-    return false;
+    // 2nd chance: There can be accessors somewhere in the prototype chain, but
+    // for compatibility reasons we have to hide this behind a flag. Note that
+    // we explicitly exclude native accessors for now, because the stubs are not
+    // yet prepared for this scenario.
+    if (!FLAG_es5_readonly) return false;

[Vyacheslav Egorov (Google), 2012/07/04 11:48:34]

Sorry, I do not understand why es5_readonly semantics is essential here.

We already lookup and find setters on the prototype chain and then invoke them
on writes. What breaks if we start caching that?

[rossberg, 2012/07/04 13:18:17]

Perhaps it isn't necessary, but this patch amends the fixes I made earlier and
(had to) put behind that flag -- which, despite the flag's name, also fixed the
treatment of inherited setters, except for the oversight here.

+    receiver->Lookup(*name, lookup);
+    if (!lookup->IsCallbacks()) return false;
+    Handle<Object> callback(lookup->GetCallbackObject());
+    return callback->IsAccessorPair() && StoreICableLookup(lookup);
   }
 
   if (lookup->IsInterceptor() &&
@@ -1494,7 +1502,8 @@ void StoreIC::UpdateCaches(LookupResult* lookup,
         if (holder->IsGlobalObject()) return;
         if (!receiver->HasFastProperties()) return;
         code = isolate()->stub_cache()->ComputeStoreViaSetter(
-            name, receiver, Handle<JSFunction>::cast(setter), strict_mode);
+            name, receiver, holder, Handle<JSFunction>::cast(setter),
+            strict_mode);
       } else {
         ASSERT(callback->IsForeign());
         // No IC support for old-style native accessors.