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events: avoid emit() eager deopt #10568

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events: avoid emit() eager deopt
vhf Jan 2, 2017
8db2546
benchmark: fix typo "categoty" -> "category"
vhf Jan 2, 2017
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events: avoid emit() eager deopt 
This commit makes sure EventEmitter.emit() doesn't get deoptimized by
V8. The deopt happens when accessing out of bound indexes of the
`arguments` object.

This issue has been raised here: #10323 and this specific case might
become a more serious performance issue in upcoming V8 releases.
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vhf committed Jan 2, 2017
commit 91cf36959edc273376d3b011c3c48dab43c7d8c1
3 changes: 2 additions & 1 deletion lib/events.js
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Expand Up @@ -148,7 +148,8 @@ EventEmitter.prototype.emit = function emit(type) {

// If there is no 'error' event listener then throw.
if (doError) {
er = arguments[1];
if (arguments.length > 1)
er = arguments[1];
if (domain) {
if (!er)
er = new Error('Uncaught, unspecified "error" event');
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