Bug 16503

Summary: match limit takes at least 13% of the time on the SunSpider regexp-dna test
Product: WebKit Reporter: Darin Adler <darin>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Enhancement CC: ap, darin, eric, ggaren, mjs, zwarich
Priority: P3    
Version: 528+ (Nightly build)   
Hardware: Mac   
OS: OS X 10.4   
Attachments:
Description Flags
2.3% improvement none

Darin Adler
Reported 2007-12-18 10:54:28 PST
The match limit inside the regular expression execution engine slows down the regexp-dna test by about 13%. If we can find some more efficient way of preventing complex regular expressions from causing a hang, then we could get a substantial speed-up. See bug 16458 for some history.
Attachments
2.3% improvement (1.49 KB, patch)
2008-05-29 08:02 PDT, Alexey Proskuryakov 		no flags
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Alexey Proskuryakov
Comment 1 2008-05-29 08:02:00 PDT
Created attachment 21408 [details] 2.3% improvement Removing the check altogether is a 9.5% win on my machine. I guess this micro-optimization is unnecessary if someone has a real fix in mind, but I thought it was worth posting anyway.
Darin Adler
Comment 2 2008-05-29 09:33:37 PDT
Comment on attachment 21408 [details] 2.3% improvement r=me I'm not sure anyone has a handle on a "real fix".
Cameron Zwarich (cpst)
Comment 3 2008-06-08 22:36:51 PDT
Alexey, are you going to land this?
Alexey Proskuryakov
Comment 4 2008-06-09 04:28:33 PDT
I'm trying to land this periodically, but random code generation changes elsewhere cause it to be a regression overall now. One of these days, I'll get lucky and have it landed.
Alexey Proskuryakov
Comment 5 2008-06-10 07:56:39 PDT
Comment on attachment 21408 [details] 2.3% improvement Landed in r34480, clearing review flag. Today, the win on regexp-dna was only 0.6%, but the total win was huge (0.5%), apparently due to random code generation changes.
Alexey Proskuryakov
Comment 6 2010-06-11 17:36:13 PDT
Something was landed here, so marking fixed. The rest of the bug is likely long obsolete.
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