Subj : Re: SpiderMonkey RegExp rewrite has landed
To   : PhilSchwartau@aol.com
From : Phil Schwartau <PhilSchwartau@aol.com>
Date : Wed Oct 22 2003 06:17 pm

I should point out, a similar landing has also gone into Rhino:
see http://bugzilla.mozilla.org/show_bug.cgi?id=125562

Phil


Phil Schwartau wrote:
> Hi,
> 
> A new landing has gone in, rewriting the regular expression engine
> in SpiderMonkey. Brendan and zack-weg@gmx.de mentioned this in recent 
> postings, but I wanted to explicitly call attention to it, since it
> will change SpiderMonkey RegExp output in certain cases.
> 
> The rewrite was originally undertaken to fix performance issues:
> http://bugzilla.mozilla.org/show_bug.cgi?id=85721
> "Regexp performance degraded from 4.7"
> 
> However, it additionally corrects certain errors contributors had 
> reported in our RegExp matching. JS users should be aware of this
> in case they notice a change in SpiderMonkey RegExp output.
> 
> For details, see the long list of bugs listed either as dependencies
> on bug 85721, or duped against it. The correctness issues in these bugs 
> have all been incorporated into the RegExp rewrite.
> 
> For example, one important change is outlined here:
> 
> http://bugzilla.mozilla.org/show_bug.cgi?id=123437
> "Regexp backreferences /(a)? etc./ must hold |undefined| if not used"
> 
> Please file new bugs on any remaining issues, performance or correctness.
> 
> A set of RegExp tests exists in mozilla/js/tests/ecma_3/RegExp/.
> It includes two very large tests benchmarking SpiderMonkey for 
> correctness against the Perl 5 regular expression engine:
> 
> http://lxr.mozilla.org/mozilla/source/js/tests/ecma_3/RegExp/perlstress-001.js 
> 
> http://lxr.mozilla.org/mozilla/source/js/tests/ecma_3/RegExp/perlstress-002.js 
> 
> 
> Phil
>

.