Bug 280827 – REGRESSION: 282146@main made text entry in a quip document very slow

• Component: DOM
• Status: RESOLVED FIXED

[Chris Dumez]

282146@main made text entry in a quip document very slow, with most of the CPU time going into WeakHashSet's amortized cleanup:
```
Sample Count, Samples%, Normalized CPU %, Symbol
5965, 19.3%, 6.4%, void WebCore::RenderLayerCompositor::applyToCompositedLayerIncludingDescendants<WebCore::RenderLayerCompositor::updateEventRegions()::$_0>(WebCore::RenderLayer&, WebCore::RenderLayerCompositor::updateEventRegions()::$_0 const&) (in WebCore)
5944, 19.2%, 6.4%,     WebCore::RenderLayerBacking::updateEventRegion() (in WebCore)
5942, 19.2%, 6.4%,         WebCore::RenderLayerBacking::updateEventRegion()::$_1::operator()(WebCore::GraphicsLayer&) const (in WebCore)
5942, 19.2%, 6.4%,             WebCore::RenderLayerBacking::paintIntoLayer(WebCore::GraphicsLayer const*, WebCore::GraphicsContext&, WebCore::IntRect const&, WTF::OptionSet<WebCore::PaintBehavior>, WebCore::RegionContext*) (in WebCore)
5942, 19.2%, 6.4%,                 WebCore::RenderLayerBacking::paintIntoLayer(WebCore::GraphicsLayer const*, WebCore::GraphicsContext&, WebCore::IntRect const&, WTF::OptionSet<WebCore::PaintBehavior>, WebCore::RegionContext*)::$_0::operator()(WebCore::RenderLayer&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) const (in WebCore)
5942, 19.2%, 6.4%,                     WebCore::RenderLayer::paintLayerContents(WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) (in WebCore)
5939, 19.2%, 6.4%,                         WebCore::RenderLayer::paintLayerWithEffects(WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) (in WebCore)
5938, 19.2%, 6.4%,                             WebCore::RenderLayer::paintLayerContents(WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) (in WebCore)
5690, 18.4%, 6.1%,                                 WebCore::RenderLayer::paintLayerWithEffects(WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) (in WebCore)
5668, 18.3%, 6.1%,                                     WebCore::RenderLayer::paintLayerContents(WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::RenderLayer::PaintLayerFlag>) (in WebCore)
5564, 18.0%, 6.0%,                                         WebCore::RenderLayer::collectEventRegionForFragments(WTF::Vector<WebCore::LayerFragment, 1ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc> const&, WebCore::GraphicsContext&, WebCore::RenderLayer::LayerPaintingInfo const&, WTF::OptionSet<WebCore::PaintBehavior>) (in WebCore)
5559, 18.0%, 6.0%,                                             WebCore::RenderBlock::paint(WebCore::PaintInfo&, WebCore::LayoutPoint const&) (in WebCore)
5557, 18.0%, 6.0%,                                                 WebCore::RenderBlock::paintObject(WebCore::PaintInfo&, WebCore::LayoutPoint const&) (in WebCore)
4325, 14.0%, 4.7%,                                                     WTF::WeakHashMap<WebCore::Node, unsigned int, WebCore::WeakPtrImplWithEventTargetData>::removeNullReferences() (in WebCore)
4325, 14.0%, 4.7%,                                                         bool WTF::HashTable<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>, WTF::KeyValuePair<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>, unsigned int>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>, unsigned int>>, WTF::DefaultHash<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>>, WTF::HashMap<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>, unsigned int, WTF::DefaultHash<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>>, WTF::HashTraits<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>>, WTF::HashTraits<unsigned int>, WTF::HashTableTraits>::KeyValuePairTraits, WTF::HashTraits<WTF::Ref<WebCore::WeakPtrImplWithEventTargetData, WTF::RawPtrTraits<WebCore::WeakPtrImplWithEventTargetData>, WTF::DefaultRefDerefTraits<WebCore::WeakPtrImplWithEventTargetData>>>>::removeIf<WTF::WeakHashMap<WebCore::Node, unsigned int, WebCore::WeakPtrImplWithEventTargetData>::removeNullReferences()::'lambda'(auto&)>(auto const&) (in WebCore)
```

[Chris Dumez]

<rdar://137203711>

[Chris Dumez]

Pull request: https://github.com/WebKit/WebKit/pull/34630

[EWS]

Committed 284643@main (00b6cbd15cad): <https://commits.webkit.org/284643@main>

Reviewed commits have been landed. Closing PR #34630 and removing active labels.

[EWS]

Committed 283286.215@safari-7620-branch (919d995357f5): <https://commits.webkit.org/283286.215@safari-7620-branch>

Reviewed commits have been landed. Closing PR #1979 and removing active labels.