Bug 68588

Summary:

[CG] ImageBufferData::getData has an invariant comparison in the inner part of a loop which doesn't get optimized out

Product:

WebKit

Reporter:

Tim Horton <thorton>

Component:

Layout and Rendering

Assignee:

Tim Horton <thorton>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

simon.fraser, webkit-bug-importer, webkit.review.bot

Priority:

Keywords:

InRadar

Version:

528+ (Nightly build)

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
"repro"	none
patch	none
style fix	none
patch	none

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	Details Formatted Diff Diff
style fix (5.30 KB, patch) 2011-09-21 17:35 PDT, Tim Horton	no flags	Details Formatted Diff Diff
patch (5.71 KB, patch) 2011-09-21 18:07 PDT, Tim Horton	no flags	Details Formatted Diff Diff
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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