Bug 250885

Summary: [ iOS Release arm64 ] css3/filters/effect-contrast-hw.html is a constant image failure
Product: WebKit Reporter: Bri Harris <bharris9>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: ap, sabouhallawa, simon.fraser, webkit-bot-watchers-bugzilla, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Image Diffs for Failing Test none

Description Bri Harris 2023-01-19 18:12:54 PST 
css3/filters/effect-contrast-hw.html

is a constant image only failure on iOS 16 release running on Apple Silicon only. 

HISTORY: 
https://results.webkit.org/?suite=layout-tests&test=css3%2Ffilters%2Feffect-contrast-hw.html&architecture=arm64

IMAGE DIFF URL: 
https://build.webkit.org/results/Apple-iOS-16-Simulator-Release-arm64-WK2-Tests/259102@main%20(754)/css3/filters/effect-contrast-hw-diffs.html

image diff images attached to bug.
Comment 1 Bri Harris 2023-01-19 18:14:07 PST 
Created attachment 464571 [details]
Image Diffs for Failing Test
Comment 2 Bri Harris 2023-01-19 18:17:07 PST 
I was able to reproduce this failure on my Apple Silicon Mac at iOS 16 Release ToT running the test as follows:

Run-Webkit-Tests css3/filters/effect-contrast-hw.html

Scrolling backwards in the history, it appears this test has been a constant image failure since we started running testing on iOS 16.
Comment 3 Radar WebKit Bug Importer 2023-01-19 18:18:15 PST 
<rdar://problem/104456051>
Comment 4 Alexey Proskuryakov 2023-01-19 19:16:26 PST 
This is a curious diff - it's not the colors that are different, but box sizes! Are contrast filters doing the wrong thing at the edges?
Comment 5 Simon Fraser (smfr) 2023-01-20 10:24:15 PST 
It's possible the CoreAnimation's contrast filter has slightly different behavior. But I think it's OK to just increase the pixel tolerance here.
Comment 6 Alexey Proskuryakov 2023-01-20 11:33:24 PST 
Hmm, isn't this going to create user visible cracks in page layout when this filter is used?
Comment 7 Bri Harris 2023-01-20 14:37:40 PST 
Pull request: https://github.com/WebKit/WebKit/pull/8897
Comment 8 EWS 2023-01-20 14:47:18 PST 
Test gardening commit 259154@main (9770e5c864b4): <https://commits.webkit.org/259154@main>

Reviewed commits have been landed. Closing PR #8897 and removing active labels.
Comment 9 Bri Harris 2023-01-20 15:20:56 PST 
It appears that this test has been a constant image only failure on iOS 16 simulator running only on an Apple Silicon machine since this test was introduced at :

https://commits.webkit.org/254408@main