617136 - Investigate RegExp slowness on Peacekeeper snippet

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Chris Leary [:cdleary] (not checking bugmail)]

Jandem pointed out this example, derived from Dromaeo.

function f(ua) {
    var x = 0;
    var t0 = new Date;
    for(var i=0; i<10000000; i++) {
	//var ua1 = ua + i;
	if (/Windows/.exec(ua)) 
	    x++;
    }
    alert(new Date - t0);
    return x;
}
f("Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727)");

<jandem> bz: when i change exec to test... FF4: 3600 ms, latest webkit nightly: 2200 ms, opera 980 ms...

Comment 1

[Jan de Mooij [:jandem]]

Not Dromaeo but Peacekeeper. stringDetectBrowser test (see http://hg.mozilla.org/users/mpalmgren_mozilla.com/peacekeeper) But I think it's a general regexp problem, so it affects Dromaeo too.

Comment 2

[Steve Fink [:sfink] [:s:]]

Isn't this one fixed now?

Comment 3

[Boris Zbarsky [:bzbarsky]]

Seems to be in the sense that exec() and test() do equally fast (or slowly?) on the testcase from comment 0 in latest nightly.

We're faster than Chrome there, but slower than Opera....

Comment 4

[Chris Leary [:cdleary] (not checking bugmail)]

That sounds fixed to me (by Brian's bug to elide object creation in the regexp literal exec case). Reopen if there are objections.