929507 - Yarr is not compiling jQuery selector parsing regexp

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Jan de Mooij [:jandem]]

The domJQueryContentFilters test in bug 922063 spends a lot of time running in the Yarr interpreter. For the reduced testcase below I get the following numbers:

d8:   5 ms
SM: 101 ms

var re = /(^(?:.|\r|\n)*?)#((?:[\w\u00c0-\uFFFF\-]|\\.)+)(?![^\[]*\])(?![^\(]*\))/;
function f() {
    var t = new Date;
    for (var i=0; i<36000; i++)
	res = re.exec("p:contains('Sega')");
    print(new Date - t);
    return res;
}
f();

Comment 1

[Till Schneidereit [:till]]

The problem here is that Yarr can't compile nested parenthesized groups. See https://bugs.webkit.org/show_bug.cgi?id=42264 for details, but basically, Yarr allocates the stack for a compiled regexp in advance and can't deal with dynamically-sized stacks.

This is a fundamental issue that we're very unlikely to be able to solve on our side. :(

Comment 2

[Chris Peterson [:cpeterson]]

This bug is no longer relevant because bug 976446 replaced YARR with irregexp.