1144925 - Use a callback tracer to do gray root buffering

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect)

Description

[Terrence Cole [:terrence]]

Attachment: 2.10_graybuffering_via_callback-v0.diff

With the prior patches in place, we can now switch this out with minimal fuss. We still need to move all of this to RootMarking.cpp where it belongs -- try run will follow after that.

Comment 1

[Jon Coppeard (:jonco)]

Comment on attachment 8579653 [details] [diff] [review]
2.10_graybuffering_via_callback-v0.diff

Review of attachment 8579653 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/gc/RootMarking.cpp
@@ -561,5 @@
>      MOZ_ASSERT(grayBufferState == GrayBufferState::Unused);
>      for (GCZonesIter zone(rt); !zone.done(); zone.next())
>          MOZ_ASSERT(zone->gcGrayRoots.empty());
>  
> -    // Transform the GCMarker into an unholy CallbackTracer doppleganger.

Nice, let's slay that doppelganger.

::: js/src/gc/Tracer.h
@@ +339,5 @@
> +    BufferGrayRootsTracer(JSRuntime *rt)
> +      : JSTracer(rt, shim), bufferingGrayRootsFailed(false)
> +    {}
> +
> +    static void shim(JSTracer *trc, void **thingp, JSGCTraceKind kind) {

Can we have a more descriptive name here?  Something like 'grayTraceCallback' maybe.

Comment 2

[Terrence Cole [:terrence]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=bdfa967ba81a
https://hg.mozilla.org/integration/mozilla-inbound/rev/55e5147d448e

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/55e5147d448e