1405330 - Clean up and optimize Promise debugger hooks

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[Jan de Mooij [:jandem]]

Attachment: Patch

The Promise constructor spends quite a lot of time under JS::dbg::onNewPromise. Fortunately this no longer has to be a public API and we can now simplify/optimize this code. In particular the fast path can just check cx->compartment()->isDebuggee().

This improves the micro-benchmark below from 360-390 ms to 340-350 ms with --no-async-stacks so it's a pretty easy win.

function f() {
    var count = 1000000;
    var start = Date.now();
    for (var i = 0; i < count; ++i) {
        new Promise(r => void 0);
    }
    var stop = Date.now();
    print(stop - start);
}
f();

Comment 1

[Till Schneidereit [:till]]

Comment on attachment 8914760 [details] [diff] [review]
Patch

Review of attachment 8914760 [details] [diff] [review]:
-----------------------------------------------------------------

Nice easy win indeed, thanks!

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/0b08540034c0
Clean up and optimize Promise debugger hooks. r=till

Comment 3

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

Backed out for failures like https://treeherder.mozilla.org/logviewer.html#?job_id=134744425&repo=mozilla-inbound

https://hg.mozilla.org/integration/mozilla-inbound/rev/810131b10010bc4f2be43d63a7dc1abe31d327cb

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/df08c7645b1a
Clean up and optimize Promise debugger hooks. r=till

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/df08c7645b1a