Bug 212032

Summary: Implement a faster findBitInWord() using the hardware ctz instruction.
Product: WebKit Reporter: Mark Lam <mark.lam>
Component: Web Template FrameworkAssignee: Mark Lam <mark.lam>
Status: RESOLVED FIXED    
Severity: Normal CC: annulen, benjamin, cdumez, cmarcelo, ews-watchlist, gyuyoung.kim, ryuan.choi, saam, sergio, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
proposed patch. saam: review+

Mark Lam
Reported 2020-05-18 10:32:31 PDT
...
Attachments
proposed patch. (18.16 KB, patch)
2020-05-18 11:19 PDT, Mark Lam 		saam: review+
DetailsFormatted DiffDiff
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Radar WebKit Bug Importer
Comment 1 2020-05-18 10:33:00 PDT
<rdar://problem/63348086>
Mark Lam
Comment 2 2020-05-18 11:19:06 PDT
Created attachment 399659 [details] proposed patch.
Saam Barati
Comment 3 2020-05-18 11:47:10 PDT
Comment on attachment 399659 [details] proposed patch. View in context: https://bugs.webkit.org/attachment.cgi?id=399659&action=review r=me > Source/bmalloc/bmalloc/Algorithm.h:239 > + if ((index < endIndex) && word) { I don't think we need the first (index < endIndex) check. Also, I'd expect this algorithm below of ctz to just work on zero too, since that'd put us past the endIndex. however, as you said, maybe ctz doesn't do good things for zero? I just find that very surprising Ditto about WTF code.
Mark Lam
Comment 4 2020-05-18 13:18:57 PDT
Thanks for the review. I've removed the extra check. Landed in r261827: <http://trac.webkit.org/r261827>.
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