Bug 301668 – REGRESSION(301964@main): [ macOS ] fast/repaint/iframe-avoid-redundant-repaint.html is a constant text failure

• Component: Layout and Rendering
• Status: NEW

[Bryan Medina]

fast/repaint/iframe-avoid-redundant-repaint.html

is a constant text failure on macOS Debug and a flaky failure on Tahoe A wk1 Release on arm64 and Sequoia F wk1 Release arm64

HISTORY:
https://results.webkit.org/?suite=layout-tests&test=fast%2Frepaint%2Fiframe-avoid-redundant-repaint.html

TEXT DIFF:
--- /Volumes/Data/worker/macOS-Tahoe-Debug-WK2-Tests-EWS/build/layout-test-results/fast/repaint/iframe-avoid-redundant-repaint-expected.txt
+++ /Volumes/Data/worker/macOS-Tahoe-Debug-WK2-Tests-EWS/build/layout-test-results/fast/repaint/iframe-avoid-redundant-repaint-actual.txt
@@ -1,6 +1,5 @@
 
 (repaint rects
   (rect 10 10 300 300)
-  (rect 10 10 300 300)
 )
 
TEXT DIFF URL:
https://ews-build.s3-us-west-2.amazonaws.com/macOS-Tahoe-Debug-WK2-Tests-EWS/50b3a459-716-clean-tree/fast/repaint/iframe-avoid-redundant-repaint-diff.txt

REPRODUCIBILITY:
I was able to reproduce the text failure locally on my device running macOS Tahoe Debug ToT using the following command
run-webkit-tests fast/repaint/iframe-avoid-redundant-repaint.html --debug --iterations=20

[Radar WebKit Bug Importer]

<rdar://problem/163677733>

[Bryan Medina]

Pull request: https://github.com/WebKit/WebKit/pull/53179

[EWS]

Test gardening commit 302322@main (85eb57515cff): <https://commits.webkit.org/302322@main>

Reviewed commits have been landed. Closing PR #53179 and removing active labels.

[Bryan Medina]

It looks like the test started to fail after changes were made at 301964@main, as that is where repaint tests were modified.

[Alexey Proskuryakov]

The diff looks like a progression – getting even fewer repaints now.

Flaky aspect is not good though, as we can't just update the results.

[Simon Fraser (smfr)]

The flakiness comes from whether the iframe repaints happen inside a `Document::updateLayout` or not:

One rect:

14:35:58.739 43580   LocalFrameView::setTracksRepaints 1
14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout
14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout done
14:35:58.739 43580   RepaintRegionAccumulator - Document::resolveStyle
14:35:58.739 43580   RepaintRegionAccumulator - Document::resolveStyle done
14:35:58.739 43580   Page::updateRendering()
14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout
14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout done

14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout
14:35:58.739 43580   RepaintRegionAccumulator - LocalFrameViewLayoutContext::performLayout
14:35:58.739 43580   RenderView 0x118229b20 repaintViewRectangle (0,0) width=300 height=300 (accumulating 1)
14:35:58.739 43580   RepaintRegionAccumulator - LocalFrameViewLayoutContext::performLayout done
14:35:58.739 43580   RenderView 0x118229b20 repaintViewRectangle (0,0) width=300 height=304 (accumulating 1)
14:35:58.739 43580   RepaintRegionAccumulator - Document::updateLayout done

Two rects:

14:35:58.852 43580   LocalFrameView::setTracksRepaints 1
14:35:58.852 43580   RepaintRegionAccumulator - Document::updateLayout
14:35:58.852 43580   RepaintRegionAccumulator - Document::updateLayout done
14:35:58.852 43580   RepaintRegionAccumulator - Document::resolveStyle
14:35:58.852 43580   RepaintRegionAccumulator - Document::resolveStyle done
14:35:58.852 43580   RepaintRegionAccumulator - LocalFrameViewLayoutContext::performLayout
14:35:58.852 43580   RenderView 0x118228c60 repaintViewRectangle (0,0) width=300 height=300 (accumulating 1)
14:35:58.852 43580   RepaintRegionAccumulator - LocalFrameViewLayoutContext::performLayout done
14:35:58.852 43580   RenderView 0x118228c60 repaintViewRectangle (0,0) width=300 height=304 (accumulating 0)