css3/background/background-repeat-round-auto2.html is an image failure on iOS EWS queue. This does not appear on the results database: HISTORY: https://results.webkit.org/?suite=layout-tests&test=css3%2Fbackground%2Fbackground-repeat-round-auto2.html DIFF IMAGES WILL BE ATTACHED. DIFF-URL: https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456887-12620/css3/background/background-repeat-round-auto2-diffs.html
<rdar://problem/91454381>
Created attachment 456995 [details] BUG238965 DIFFS
Antialiasing around edges. Probably a preceding test leaving something graphics related in a bad state. Finding a repro case would help see if it's something we can fix.
(In reply to Alexey Proskuryakov from comment #3) > Antialiasing around edges. Probably a preceding test leaving something > graphics related in a bad state. Finding a repro case would help see if it's > something we can fix. I knew it! - You had commented on a previous bug I had made and said it was antialiasing and this appeared to be very similar to that... I'll bisect a test list for this and attempt to reproduce the failure and detect the preceding test.
> https://ews-build.s3-us-west-2.amazonaws.com/iOS-15-Simulator-WK2-Tests-EWS/456887-12620/css3/background/background-repeat-round-auto2-diffs.html Build link for this: https://ews-build.webkit.org/#/builders/68/builds/12620 What's interesting is that this is EWS, so failing a test means that it fails as part of the main test suite first, but also fails on retry with --singly, so it's actually not about any preceding tests in the process. In this run, it failed like this first: 11:31:31.809 80268 [1361/53799] css3/background/background-repeat-round-auto2.html failed unexpectedly (reference mismatch maxDifference=1; totalPixels=360) 11:31:31.810 80268 worker/4 css3/background/background-repeat-round-auto2.html failed: 11:31:31.810 80268 worker/4 reference mismatch maxDifference=1; totalPixels=360 And then: 12:30:58.239 80268 [2/14] css3/background/background-repeat-round-auto2.html failed unexpectedly (reference mismatch maxDifference=1; totalPixels=94) 12:30:58.239 80268 css3/background/background-repeat-round-auto2.html failed: 12:30:58.239 80268 reference mismatch maxDifference=1; totalPixels=94 12:30:58.240 80268 finished test group Only some of the circles had antialiasing diffs on retry!
Created attachment 457549 [details] retry diff
Created attachment 457550 [details] first try diff
css3/background/background-repeat-round-auto1.html Seems to also be an Antialiasing issue, Duping that bug onto this one. https://bugs.webkit.org/show_bug.cgi?id=238781
*** Bug 238781 has been marked as a duplicate of this bug. ***
The various diffs show that that antialiasing differences can be limited to just some CALayers (page tiles).
I think we need to bring back the built-in tolerance of 1 per color component.
This is cause by using different GPU shaders on different layers. These shaders are not expected to be exact, and results can differ by 1 per component. ImageDiff does have built-in tolerance (we don't use --exact), but here three color components are different by 1/255: difference: exact 0 legacyDistance 0.00656 threshold 0.00392 over 1 133 132 133 132 133 132 255 255
Created attachment 458178 [details] ImageDiff tolerance patch
Created attachment 458291 [details] Patch
Created attachment 458323 [details] Patch
Tools/Scripts/svn-apply failed to apply attachment 458323 [details] to trunk. Please resolve the conflicts and upload a new patch.
https://trac.webkit.org/r293447