1068697 - Add a compartment option to preserve JIT code in non-shrinking GCs

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect)

Description

[Jon Coppeard (:jonco)]

Requested by Wildfire Games for their game 0 A.D.

The situation is an embedding of SpiderMonkey with a fixed set of scripts.  It does not make sense to throw away JIT code on every GC only to recompile it again later.  Testing using the test function gcPreserveCode() shows a measurable performance improvement.

The idea is to add a per-compartment option to preserve JIT code for that compartment.  Like the current (global) situation with gcPreserveCode() JIT code is still discarded on a shrinking GC.

Comment 1

[Jon Coppeard (:jonco)]

Some performance measurements are given here:

http://www.wildfiregames.com/forum/index.php?showtopic=18466&page=2#entry298215

Comment 2

[Jon Coppeard (:jonco)]

Attachment: preserve-jit-code-option

And here's a patch to implement it.

Comment 3

[Terrence Cole [:terrence]]

Comment on attachment 8491549 [details] [diff] [review]
preserve-jit-code-option

Review of attachment 8491549 [details] [diff] [review]:
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Nice! Thanks for taking this.

Comment 4

[Jon Coppeard (:jonco)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/32c2b586c572

Comment 5

[Ryan VanderMeulen [:RyanVM]]

This did land on mozilla-central, though the bug didn't get marked. Sorry for any confusion.
https://hg.mozilla.org/mozilla-central/rev/32c2b586c572