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lib,tools: fix perm deopts #13384

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mscdex merged 4 commits into from
Jun 5, 2017
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lib,tools: fix perm deopts #13384

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8cc8358
tools: fix node args passing in test runner
mscdex Jun 2, 2017
e374e44
events: fix potential permanent deopt
mscdex Jun 2, 2017
fc6f487
process: fix permanent deopt
mscdex Jun 2, 2017
d081548
net: fix permanent deopt
mscdex Jun 2, 2017
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events: fix potential permanent deopt 
PR-URL: #13384
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
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mscdex committed Jun 5, 2017
commit e374e44a8a1bed599379fdcf4b5fe142c5e5187d
19 changes: 17 additions & 2 deletions lib/events.js
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Expand Up @@ -306,10 +306,25 @@ EventEmitter.prototype.prependListener =
};

function onceWrapper() {
this.target.removeListener(this.type, this.wrapFn);
if (!this.fired) {
this.target.removeListener(this.type, this.wrapFn);
this.fired = true;
this.listener.apply(this.target, arguments);
switch (arguments.length) {
case 0:
return this.listener.call(this.target);
case 1:
return this.listener.call(this.target, arguments[0]);
case 2:
return this.listener.call(this.target, arguments[0], arguments[1]);
case 3:
return this.listener.call(this.target, arguments[0], arguments[1],
arguments[2]);
default:
const args = new Array(arguments.length);
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@lpinca lpinca Jun 3, 2017

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Can arrayClone() be reused here or does it have a negative performance impact?

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@mscdex mscdex Jun 3, 2017

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No, because you cannot pass arguments without penalty except in only one or two cases. apply() is supposed to be one of those cases (which is what was used here before) but for some reason it can still cause a deopt (noticed this in some net benchmarks and tests).

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@refack refack Jun 3, 2017

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does (...args) work (for everything) any better?
Ref: #12183

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@mscdex mscdex Jun 3, 2017

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Rest parameters are still slower than fast path cases like those used above. I think rest params in general are getting faster, but still not quite where they need to be to replace fast paths.

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@refack refack Jun 3, 2017

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👍

for (var i = 0; i < args.length; ++i)
args[i] = arguments[i];
this.listener.apply(this.target, args);
}
}
}

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