1370614 - Replace some uses of ProtoAndIfaceCache::EntrySlotIfExists with something that returns a boolean

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement)

Description

[Boris Zbarsky [:bzbarsky]]

Right now we return a JSObject*, which means we end up barriering on it and doing exposeToJS.  There's no need to do that; all the consumers just want to know whether it's null.  So we could return a boolean, which Heap<JSObject*> can produce without barriering.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Replace some uses of ProtoAndIfaceCache::EntrySlotIfExists with a faster boolean-returning test function

Comment 2

[Nathan Froyd [:froydnj]]

Comment on attachment 8874953 [details] [diff] [review]
Replace some uses of ProtoAndIfaceCache::EntrySlotIfExists with a faster boolean-returning test function

Review of attachment 8874953 [details] [diff] [review]:
-----------------------------------------------------------------

::: dom/bindings/BindingUtils.h
@@ +319,5 @@
>        }
>        return (*p)[leafIndex];
>      }
>  
> +    bool HasEntryInSlot(size_t i) {

Would be nice if there was a way to write this function without so much duplication, but... :(

Comment 3

[Boris Zbarsky [:bzbarsky]]

Yeah, I couldn't figure out a way to do that, without doing manual exposing stuff or something.  I thought I could nix EntrySlotIfExists completely, but we do have one single consumer of it that actually wants the JSObject*.

That said, maybe I can just switch ResolvePrototypeOrConstructor to EntrySlotMustExist. I believe in all cases when it's used this is in fact true...  and the current behavior when null is returned is a bit bonkers anyway (uncatchable exception).  Filed bug 1370640.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/b84707ac2dfe
Replace some uses of ProtoAndIfaceCache::EntrySlotIfExists with a faster boolean-returning test function.  r=froydnj

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/b84707ac2dfe