RESOLVED FIXED Bug 68588
[CG] ImageBufferData::getData has an invariant comparison in the inner part of a loop which doesn't get optimized out 
https://bugs.webkit.org/show_bug.cgi?id=68588
Summary [CG] ImageBufferData::getData has an invariant comparison in the inner part o...
Tim Horton
Reported 2011-09-21 17:23:57 PDT
The test of "unmultiplied" inside the inner loop of ImageBufferData::getData is unnecessary; unmultiplied won't change during the course of this calculation. I would have expected this to be optimized out by the compiler, but this patch provides a consistent and reproducible 1.7x speedup (visible with Instruments) in ImageBufferData::getData in the not-unmultiplied case with the attached test case (requires filters to be turned on).
Attachments
"repro" (732 bytes, image/svg+xml)
2011-09-21 17:29 PDT, Tim Horton 		no flags
Details
patch (5.32 KB, patch)
2011-09-21 17:29 PDT, Tim Horton 		no flags
DetailsFormatted DiffDiff
style fix (5.30 KB, patch)
2011-09-21 17:35 PDT, Tim Horton 		no flags
DetailsFormatted DiffDiff
patch (5.71 KB, patch)
2011-09-21 18:07 PDT, Tim Horton 		no flags
DetailsFormatted DiffDiff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2011-09-21 17:24:24 PDT
<rdar://problem/10164955>
Tim Horton
Comment 2 2011-09-21 17:29:11 PDT
Created attachment 108257 [details] "repro"
Tim Horton
Comment 3 2011-09-21 17:29:39 PDT
Created attachment 108259 [details] patch
WebKit Review Bot
Comment 4 2011-09-21 17:32:31 PDT
Attachment 108259 [details] did not pass style-queue: Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/WebCore/ChangeLog', u'Source/WebCor..." exit_code: 1 Source/WebCore/platform/graphics/cg/ImageBufferDataCG.cpp:195: One line control clauses should not use braces. [whitespace/braces] [4] Total errors found: 1 in 2 files If any of these errors are false positives, please file a bug against check-webkit-style.
Tim Horton
Comment 5 2011-09-21 17:35:42 PDT
Created attachment 108260 [details] style fix
Tim Horton
Comment 6 2011-09-21 17:36:11 PDT
I should note that I was testing this on a release build.
Tim Horton
Comment 7 2011-09-21 18:07:49 PDT
Created attachment 108263 [details] patch Mark noted that with this patch, I'm not assigning any data in the case of 0 alpha. Fixed.
Simon Fraser (smfr)
Comment 8 2011-09-21 18:38:51 PDT
Comment on attachment 108263 [details] patch View in context: https://bugs.webkit.org/attachment.cgi?id=108263&action=review This code grows more and more unwieldy with each change. > Source/WebCore/platform/graphics/cg/ImageBufferDataCG.cpp:195 > + reinterpret_cast<uint32_t*>(destRows + x)[0] = reinterpret_cast<uint32_t*>(srcRows + x)[0]; Can this be a memcpy?
WebKit Review Bot
Comment 9 2011-09-21 19:03:36 PDT
Comment on attachment 108263 [details] patch Clearing flags on attachment: 108263 Committed r95695: <http://trac.webkit.org/changeset/95695>
WebKit Review Bot
Comment 10 2011-09-21 19:03:41 PDT
All reviewed patches have been landed. Closing bug.
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