RESOLVED FIXED 212032
Implement a faster findBitInWord() using the hardware ctz instruction. 
https://bugs.webkit.org/show_bug.cgi?id=212032
Summary Implement a faster findBitInWord() using the hardware ctz instruction.
Mark Lam
Reported 2020-05-18 10:32:31 PDT
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Attachments
proposed patch. (18.16 KB, patch)
2020-05-18 11:19 PDT, Mark Lam 		saam: review+
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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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