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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/206639">206639</a></dd>
<dt>Author</dt> <dd>zalan@apple.com</dd>
<dt>Date</dt> <dd>2016-09-30 09:52:47 -0700 (Fri, 30 Sep 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>RenderLayer::clipRects may return nullptr.
https://bugs.webkit.org/show_bug.cgi?id=162729
Reviewed by Chris Dumez.
This patch refactors RenderLayer::updateClipRects(), parentClipRects() and backgroundClipRect()
so that we don't have to rely on this seemingly unsafe line: clipRects = *parent()->clipRects(clipRectsContext);
Now updateClipRects() returns the computed/cached clip rects as opposed to update and refetch them.
While this patch makes the code look more readable/safer, it also eliminates cached item tripple retrievals.
No change in functionality.
* rendering/RenderLayer.cpp:
(WebCore::ClipRectsCache::getClipRects):
(WebCore::ClipRectsCache::setClipRects):
(WebCore::RenderLayer::updateClipRects):
(WebCore::RenderLayer::clipRects):
(WebCore::RenderLayer::calculateClipRects):
* rendering/RenderLayer.h:</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayercpp">trunk/Source/WebCore/rendering/RenderLayer.cpp</a></li>
<li><a href="#trunkSourceWebCorerenderingRenderLayerh">trunk/Source/WebCore/rendering/RenderLayer.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (206638 => 206639)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2016-09-30 16:41:20 UTC (rev 206638)
+++ trunk/Source/WebCore/ChangeLog 2016-09-30 16:52:47 UTC (rev 206639)
</span><span class="lines">@@ -1,3 +1,25 @@
</span><ins>+2016-09-30 Zalan Bujtas <zalan@apple.com>
+
+ RenderLayer::clipRects may return nullptr.
+ https://bugs.webkit.org/show_bug.cgi?id=162729
+
+ Reviewed by Chris Dumez.
+
+ This patch refactors RenderLayer::updateClipRects(), parentClipRects() and backgroundClipRect()
+ so that we don't have to rely on this seemingly unsafe line: clipRects = *parent()->clipRects(clipRectsContext);
+ Now updateClipRects() returns the computed/cached clip rects as opposed to update and refetch them.
+ While this patch makes the code look more readable/safer, it also eliminates cached item tripple retrievals.
+
+ No change in functionality.
+
+ * rendering/RenderLayer.cpp:
+ (WebCore::ClipRectsCache::getClipRects):
+ (WebCore::ClipRectsCache::setClipRects):
+ (WebCore::RenderLayer::updateClipRects):
+ (WebCore::RenderLayer::clipRects):
+ (WebCore::RenderLayer::calculateClipRects):
+ * rendering/RenderLayer.h:
+
</ins><span class="cx"> 2016-09-30 Youenn Fablet <youenn@apple.com>
</span><span class="cx">
</span><span class="cx"> Add a way to go from a RefPtr<T> to Ref<const T>
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayer.cpp (206638 => 206639)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayer.cpp 2016-09-30 16:41:20 UTC (rev 206638)
+++ trunk/Source/WebCore/rendering/RenderLayer.cpp 2016-09-30 16:52:47 UTC (rev 206639)
</span><span class="lines">@@ -232,8 +232,8 @@
</span><span class="cx"> #endif
</span><span class="cx"> }
</span><span class="cx">
</span><del>- PassRefPtr<ClipRects> getClipRects(ClipRectsType clipRectsType, ShouldRespectOverflowClip respectOverflow) { return m_clipRects[getIndex(clipRectsType, respectOverflow)]; }
- void setClipRects(ClipRectsType clipRectsType, ShouldRespectOverflowClip respectOverflow, PassRefPtr<ClipRects> clipRects) { m_clipRects[getIndex(clipRectsType, respectOverflow)] = clipRects; }
</del><ins>+ ClipRects* getClipRects(ClipRectsType clipRectsType, ShouldRespectOverflowClip respectOverflow) { return m_clipRects[getIndex(clipRectsType, respectOverflow)].get(); }
+ void setClipRects(ClipRectsType clipRectsType, ShouldRespectOverflowClip respectOverflow, RefPtr<ClipRects>&& clipRects) { m_clipRects[getIndex(clipRectsType, respectOverflow)] = WTFMove(clipRects); }
</ins><span class="cx">
</span><span class="cx"> #ifndef NDEBUG
</span><span class="cx"> const RenderLayer* m_clipRectsRoot[NumCachedClipRectsTypes];
</span><span class="lines">@@ -5405,46 +5405,49 @@
</span><span class="cx"> return resultLayer;
</span><span class="cx"> }
</span><span class="cx">
</span><del>-void RenderLayer::updateClipRects(const ClipRectsContext& clipRectsContext)
</del><ins>+Ref<ClipRects> RenderLayer::updateClipRects(const ClipRectsContext& clipRectsContext)
</ins><span class="cx"> {
</span><span class="cx"> ClipRectsType clipRectsType = clipRectsContext.clipRectsType;
</span><span class="cx"> ASSERT(clipRectsType < NumCachedClipRectsTypes);
</span><del>- if (m_clipRectsCache && m_clipRectsCache->getClipRects(clipRectsType, clipRectsContext.respectOverflowClip)) {
- ASSERT(clipRectsContext.rootLayer == m_clipRectsCache->m_clipRectsRoot[clipRectsType]);
- ASSERT(m_clipRectsCache->m_scrollbarRelevancy[clipRectsType] == clipRectsContext.overlayScrollbarSizeRelevancy);
</del><ins>+ if (m_clipRectsCache) {
+ if (auto* clipRects = m_clipRectsCache->getClipRects(clipRectsType, clipRectsContext.respectOverflowClip)) {
+ ASSERT(clipRectsContext.rootLayer == m_clipRectsCache->m_clipRectsRoot[clipRectsType]);
+ ASSERT(m_clipRectsCache->m_scrollbarRelevancy[clipRectsType] == clipRectsContext.overlayScrollbarSizeRelevancy);
</ins><span class="cx">
</span><span class="cx"> #ifdef CHECK_CACHED_CLIP_RECTS
</span><del>- // This code is useful to check cached clip rects, but is too expensive to leave enabled in debug builds by default.
- ClipRectsContext tempContext(clipRectsContext);
- tempContext.clipRectsType = TemporaryClipRects;
- ClipRects clipRects;
- calculateClipRects(tempContext, clipRects);
- ASSERT(clipRects == *m_clipRectsCache->getClipRects(clipRectsType, clipRectsContext.respectOverflowClip).get());
</del><ins>+ // This code is useful to check cached clip rects, but is too expensive to leave enabled in debug builds by default.
+ ClipRectsContext tempContext(clipRectsContext);
+ tempContext.clipRectsType = TemporaryClipRects;
+ ClipRects tempClipRects;
+ calculateClipRects(tempContext, tempClipRects);
+ ASSERT(tempClipRects == *clipRects);
</ins><span class="cx"> #endif
</span><del>- return; // We have the correct cached value.
</del><ins>+ return *clipRects; // We have the correct cached value.
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><del>- // For transformed layers, the root layer was shifted to be us, so there is no need to
- // examine the parent. We want to cache clip rects with us as the root.
- RenderLayer* parentLayer = clipRectsContext.rootLayer != this ? parent() : nullptr;
- if (parentLayer)
- parentLayer->updateClipRects(clipRectsContext);
-
- ClipRects clipRects;
- calculateClipRects(clipRectsContext, clipRects);
-
</del><span class="cx"> if (!m_clipRectsCache)
</span><span class="cx"> m_clipRectsCache = std::make_unique<ClipRectsCache>();
</span><del>-
- if (parentLayer && parentLayer->clipRects(clipRectsContext) && clipRects == *parentLayer->clipRects(clipRectsContext))
- m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, parentLayer->clipRects(clipRectsContext));
- else
- m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, ClipRects::create(clipRects));
-
</del><span class="cx"> #ifndef NDEBUG
</span><span class="cx"> m_clipRectsCache->m_clipRectsRoot[clipRectsType] = clipRectsContext.rootLayer;
</span><span class="cx"> m_clipRectsCache->m_scrollbarRelevancy[clipRectsType] = clipRectsContext.overlayScrollbarSizeRelevancy;
</span><span class="cx"> #endif
</span><ins>+
+ RefPtr<ClipRects> parentClipRects;
+ // For transformed layers, the root layer was shifted to be us, so there is no need to
+ // examine the parent. We want to cache clip rects with us as the root.
+ if (auto* parentLayer = (clipRectsContext.rootLayer != this ? parent() : nullptr))
+ parentClipRects = parentLayer->updateClipRects(clipRectsContext);
+
+ auto clipRects = ClipRects::create();
+ calculateClipRects(clipRectsContext, clipRects);
+
+ if (parentClipRects && *parentClipRects == clipRects) {
+ m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, parentClipRects.copyRef());
+ return parentClipRects.releaseNonNull();
+ }
+ m_clipRectsCache->setClipRects(clipRectsType, clipRectsContext.respectOverflowClip, clipRects.copyRef());
+ return clipRects;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> bool RenderLayer::mapLayerClipRectsToFragmentationLayer(ClipRects& clipRects) const
</span><span class="lines">@@ -5482,7 +5485,9 @@
</span><span class="cx"> ClipRects* RenderLayer::clipRects(const ClipRectsContext& context) const
</span><span class="cx"> {
</span><span class="cx"> ASSERT(context.clipRectsType < NumCachedClipRectsTypes);
</span><del>- return m_clipRectsCache ? m_clipRectsCache->getClipRects(context.clipRectsType, context.respectOverflowClip).get() : nullptr;
</del><ins>+ if (!m_clipRectsCache)
+ return nullptr;
+ return m_clipRectsCache->getClipRects(context.clipRectsType, context.respectOverflowClip);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void RenderLayer::calculateClipRects(const ClipRectsContext& clipRectsContext, ClipRects& clipRects) const
</span><span class="lines">@@ -5557,19 +5562,22 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><del>-void RenderLayer::parentClipRects(const ClipRectsContext& clipRectsContext, ClipRects& clipRects) const
</del><ins>+Ref<ClipRects> RenderLayer::parentClipRects(const ClipRectsContext& clipRectsContext) const
</ins><span class="cx"> {
</span><span class="cx"> ASSERT(parent());
</span><del>- if (renderer().isRenderNamedFlowThread() && mapLayerClipRectsToFragmentationLayer(clipRects))
- return;
</del><ins>+ if (renderer().isRenderNamedFlowThread()) {
+ auto parentClipRects = ClipRects::create();
+ if (mapLayerClipRectsToFragmentationLayer(parentClipRects))
+ return parentClipRects;
+ }
</ins><span class="cx">
</span><span class="cx"> if (clipRectsContext.clipRectsType == TemporaryClipRects) {
</span><del>- parent()->calculateClipRects(clipRectsContext, clipRects);
- return;
</del><ins>+ auto parentClipRects = ClipRects::create();
+ parent()->calculateClipRects(clipRectsContext, parentClipRects);
+ return parentClipRects;
</ins><span class="cx"> }
</span><span class="cx">
</span><del>- parent()->updateClipRects(clipRectsContext);
- clipRects = *parent()->clipRects(clipRectsContext);
</del><ins>+ return parent()->updateClipRects(clipRectsContext);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> static inline ClipRect backgroundClipRectForPosition(const ClipRects& parentRects, EPosition position)
</span><span class="lines">@@ -5586,25 +5594,24 @@
</span><span class="cx"> ClipRect RenderLayer::backgroundClipRect(const ClipRectsContext& clipRectsContext) const
</span><span class="cx"> {
</span><span class="cx"> ASSERT(parent());
</span><ins>+ auto computeParentRects = [this, &clipRectsContext] () {
+ // If we cross into a different pagination context, then we can't rely on the cache.
+ // Just switch over to using TemporaryClipRects.
+ if (clipRectsContext.clipRectsType != TemporaryClipRects
+ && parent()->enclosingPaginationLayer(IncludeCompositedPaginatedLayers) != enclosingPaginationLayer(IncludeCompositedPaginatedLayers)) {
+ ClipRectsContext tempContext(clipRectsContext);
+ tempContext.clipRectsType = TemporaryClipRects;
+ return parentClipRects(tempContext);
+ }
+ return parentClipRects(clipRectsContext);
+ };
</ins><span class="cx">
</span><del>- ClipRects parentRects;
-
- // If we cross into a different pagination context, then we can't rely on the cache.
- // Just switch over to using TemporaryClipRects.
- if (clipRectsContext.clipRectsType != TemporaryClipRects && parent()->enclosingPaginationLayer(IncludeCompositedPaginatedLayers) != enclosingPaginationLayer(IncludeCompositedPaginatedLayers)) {
- ClipRectsContext tempContext(clipRectsContext);
- tempContext.clipRectsType = TemporaryClipRects;
- parentClipRects(tempContext, parentRects);
- } else
- parentClipRects(clipRectsContext, parentRects);
-
</del><ins>+ auto parentRects = computeParentRects();
</ins><span class="cx"> ClipRect backgroundClipRect = backgroundClipRectForPosition(parentRects, renderer().style().position());
</span><span class="cx"> RenderView& view = renderer().view();
</span><del>-
</del><span class="cx"> // Note: infinite clipRects should not be scrolled here, otherwise they will accidentally no longer be considered infinite.
</span><del>- if (parentRects.fixed() && &clipRectsContext.rootLayer->renderer() == &view && !backgroundClipRect.isInfinite())
</del><ins>+ if (parentRects->fixed() && &clipRectsContext.rootLayer->renderer() == &view && !backgroundClipRect.isInfinite())
</ins><span class="cx"> backgroundClipRect.moveBy(view.frameView().scrollPositionForFixedPosition());
</span><del>-
</del><span class="cx"> return backgroundClipRect;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -6068,9 +6075,8 @@
</span><span class="cx"> m_clipRectsCache = nullptr;
</span><span class="cx"> else {
</span><span class="cx"> ASSERT(typeToClear < NumCachedClipRectsTypes);
</span><del>- RefPtr<ClipRects> dummy;
- m_clipRectsCache->setClipRects(typeToClear, RespectOverflowClip, dummy);
- m_clipRectsCache->setClipRects(typeToClear, IgnoreOverflowClip, dummy);
</del><ins>+ m_clipRectsCache->setClipRects(typeToClear, RespectOverflowClip, nullptr);
+ m_clipRectsCache->setClipRects(typeToClear, IgnoreOverflowClip, nullptr);
</ins><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceWebCorerenderingRenderLayerh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/rendering/RenderLayer.h (206638 => 206639)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/rendering/RenderLayer.h 2016-09-30 16:41:20 UTC (rev 206638)
+++ trunk/Source/WebCore/rendering/RenderLayer.h 2016-09-30 16:52:47 UTC (rev 206639)
</span><span class="lines">@@ -695,8 +695,8 @@
</span><span class="cx"> bool clipToDirtyRect;
</span><span class="cx"> };
</span><span class="cx">
</span><del>- // Compute and cache clip rects computed with the given layer as the root
- void updateClipRects(const ClipRectsContext&);
</del><ins>+ // Compute, cache and return clip rects computed with the given layer as the root.
+ Ref<ClipRects> updateClipRects(const ClipRectsContext&);
</ins><span class="cx"> // Compute and return the clip rects. If useCached is true, will used previously computed clip rects on ancestors
</span><span class="cx"> // (rather than computing them all from scratch up the parent chain).
</span><span class="cx"> void calculateClipRects(const ClipRectsContext&, ClipRects&) const;
</span><span class="lines">@@ -933,7 +933,7 @@
</span><span class="cx"> void dirtyAncestorChainHasBlendingDescendants();
</span><span class="cx"> #endif
</span><span class="cx">
</span><del>- void parentClipRects(const ClipRectsContext&, ClipRects&) const;
</del><ins>+ Ref<ClipRects> parentClipRects(const ClipRectsContext&) const;
</ins><span class="cx"> ClipRect backgroundClipRect(const ClipRectsContext&) const;
</span><span class="cx">
</span><span class="cx"> RenderLayer* enclosingTransformedAncestor() const;
</span></span></pre>
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