1685132 - Simplify tracing by removing the special case for tenuring in TraceEdgeInternal

Status: RESOLVED FIXED

(Core :: JavaScript: GC, enhancement, P3)

Description

[Jon Coppeard (:jonco)]

TraceEdgeInternal has to dispatch based on the tracer kind. Currently we have special cases for marking and tenuring and otherwise we use virtual dispatch. I'd like to remove the case for tenuring. It should be possible to do this without regressing performance because this path is not the hot path during tenuring.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1685132 - Remove the special case for tenuring in TraceEdgeInternal r?sfink

This simplifies tracing by removing the special case for the tenuring tracer in
TraceEdgeInternal. TenuringTracer becomes a GenericTracer and this path uses
virtual dispatch.

Most tenuring is not done by this path however and the compiler can optimise
away the virtual dispatch in the TenuringTracer::traverse methods.

I measured around 15% improvement for evicting a full nursery in local
benchmarking with this change.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8ccb4e4dcd08
Remove the special case for tenuring in TraceEdgeInternal r=sfink

Comment 3

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/8ccb4e4dcd08