1369762 - Avoid string atomization in FinishBoundFunctionInit when the bound target name is empty

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement)

Description

[André Bargull [:anba]]

These Function#bind() calls from Speedometer still show up in profiles, because of the function name atomization overhead in JSFunction::getUnresolvedName():
https://github.com/WebKit/webkit/blob/c3cb7eecbd14e0cf97f55b1014340e5b474da8d1/PerformanceTests/Speedometer/resources/todomvc/architecture-examples/react/js/app.jsx#L292-L294

"setState" is a bound function created in https://github.com/WebKit/webkit/blob/c3cb7eecbd14e0cf97f55b1014340e5b474da8d1/PerformanceTests/Speedometer/resources/todomvc/architecture-examples/react/node_modules/react/dist/react.min.js , but luckily it's anonymous function, so we can optimize for this case in JSFunction::getUnresolvedName() by special-casing empty function names. Yay! :-/

Comment 1

[André Bargull [:anba]]

Attachment: bug1369762.patch

Improves this µ-benchmark (should be similar to the React benchmark from Speedometer) from 540ms to 330ms.

    var o = {};
    o.m = function(){}.bind(o);
    var t = Date.now();
    for (var i = 0; i < 5000000; ++i) o.m.bind();
    print(Date.now() - t);

Comment 2

[Till Schneidereit [:till]]

Comment on attachment 8873877 [details] [diff] [review]
bug1369762.patch

Review of attachment 8873877 [details] [diff] [review]:
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r=me, that's an excellent speedup for such a small change.

Comment 3

[André Bargull [:anba]]

Try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=5c2f4711c9d7c5e898216a8a1a893dded9170aa5

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/45eded6a52c0
Don't atomize empty function names when retrieving the unresolved name of a bound function. r=till

Comment 5

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

https://hg.mozilla.org/mozilla-central/rev/45eded6a52c0