Avoid triggering compositing updates when only the root layer is composited

[Simon Fraser (smfr)]

Avoid triggering compositing updates when only the root layer is composited

[Simon Fraser (smfr)]

Created attachment 355206 [details]
Patch

[Simon Fraser (smfr)]

Created attachment 355211 [details]
Patch

[zalan]

Comment on attachment 355211 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=355211&action=review

> Source/WebCore/rendering/RenderLayerCompositor.cpp:1181
> +    auto appendForegroundLayerIfNecessary = [&] () {

() can be dropped here

[Simon Fraser (smfr)]

https://trac.webkit.org/changeset/238357/webkit

[Radar WebKit Bug Importer]

<rdar://problem/46152493>

[Truitt Savell]

Looks like https://trac.webkit.org/changeset/238357/webkit

Has caused three tests to fail constantly:

css3/filters/blur-filter-page-scroll-parents.html
css3/filters/blur-filter-page-scroll-self.html
css3/filters/blur-filter-page-scroll.html

History:
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=css3%2Ffilters%2Fblur-filter-page-scroll-parents.html%20css3%2Ffilters%2Fblur-filter-page-scroll-self.html%20css3%2Ffilters%2Fblur-filter-page-scroll.html

Diff of css3/filters/blur-filter-page-scroll-parents.html:
--- /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-results/css3/filters/blur-filter-page-scroll-parents-expected.txt
+++ /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-results/css3/filters/blur-filter-page-scroll-parents-actual.txt
@@ -9,5 +9,6 @@
   RenderBlock {DIV} at (0,0) size 800x1200
     RenderBlock {DIV} at (0,0) size 800x200 [bgcolor=#FF0000]
     RenderBlock {DIV} at (0,200) size 800x1000 [bgcolor=#008000]
-layer at (0,0) size 800x100
+layer at (0,100) size 800x100
   RenderBlock (positioned) {DIV} at (0,0) size 800x100 [bgcolor=#000000]
+scrolled to 0,100

[Truitt Savell]

Failures are on iOS Release WK2. Debug WK2 is crashing and may be unrelated.

[Simon Fraser (smfr)]

(In reply to Truitt Savell from comment #6)
> Looks like https://trac.webkit.org/changeset/238357/webkit
> 
> Has caused three tests to fail constantly:
> 
> css3/filters/blur-filter-page-scroll-parents.html
> css3/filters/blur-filter-page-scroll-self.html
> css3/filters/blur-filter-page-scroll.html
> 
> History:
> https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.
> html#showAllRuns=true&tests=css3%2Ffilters%2Fblur-filter-page-scroll-parents.
> html%20css3%2Ffilters%2Fblur-filter-page-scroll-self.
> html%20css3%2Ffilters%2Fblur-filter-page-scroll.html
> 
> Diff of css3/filters/blur-filter-page-scroll-parents.html:
> ---
> /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-
> results/css3/filters/blur-filter-page-scroll-parents-expected.txt
> +++
> /Volumes/Data/slave/ios-simulator-12-release-tests-wk2/build/layout-test-
> results/css3/filters/blur-filter-page-scroll-parents-actual.txt
> @@ -9,5 +9,6 @@
>    RenderBlock {DIV} at (0,0) size 800x1200
>      RenderBlock {DIV} at (0,0) size 800x200 [bgcolor=#FF0000]
>      RenderBlock {DIV} at (0,200) size 800x1000 [bgcolor=#008000]
> -layer at (0,0) size 800x100
> +layer at (0,100) size 800x100
>    RenderBlock (positioned) {DIV} at (0,0) size 800x100 [bgcolor=#000000]
> +scrolled to 0,100

These tests are trying to disable accelerated compositing, which doesn't work so well in WK2.

[Truitt Savell]

it does appear this change has caused the crashing of these three tests as well. This is effecting ews so I am going to roll it out until a fix is found.

[Truitt Savell]

Reverted r238357 for reason:

Casued three css tests to fail and crash on ios sim

Committed r238523: <https://trac.webkit.org/changeset/238523>

[Simon Fraser (smfr)]

I'm going to disable those tests for iOS WK2: bug 192045

[Simon Fraser (smfr)]

https://trac.webkit.org/r238583