Disentangle repaint-after-compositing from updateLayerPositionsAfterLayout

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index cadb60c657c9f07ffa7d796e95fa7fd8748d4454..d1ce2663253a619bb43ec21ae0a8d71bbb88fb91 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -1557,23 +1557,25 @@ void RenderBox::invalidateTreeIfNeeded(const PaintInvalidationState& paintInvali
     // FIXME: SVG should probably also go through this unified paint invalidation system.
     ASSERT(!needsLayout());
 
-    if (!shouldCheckForPaintInvalidation())
+    if (!shouldCheckForPaintInvalidation(paintInvalidationState))
         return;
 
     bool establishesNewPaintInvalidationContainer = isPaintInvalidationContainer();
     const RenderLayerModelObject& newPaintInvalidationContainer = *adjustCompositedContainerForSpecialAncestors(establishesNewPaintInvalidationContainer ? this : &paintInvalidationState.paintInvalidationContainer());
     ASSERT(&newPaintInvalidationContainer == containerForPaintInvalidation());
 
-    invalidatePaintIfNeeded(paintInvalidationState, newPaintInvalidationContainer);
+    bool didFullyInvalidatePaint = invalidatePaintIfNeeded(paintInvalidationState, newPaintInvalidationContainer);
 
     // This is for the next invalidatePaintIfNeeded so must be after invalidatePaintIfNeeded.
     savePreviousBorderBoxSizeIfNeeded();
 
     PaintInvalidationState childTreeWalkState(paintInvalidationState, *this, newPaintInvalidationContainer);
+    if (didFullyInvalidatePaint)

[Julien - ping for review, 2014/08/01 21:20:01]

AFAICT this will make us force paint invalidation for other reasons than a
containing block shift. I would bet it's the reason why we have all these extra
invalidations. Those invalidations are not over-painting but they are a sign
that we are doing too much work.

I would be more comfortable if we limited this condition to only when we
actually need it.

[abarth-chromium, 2014/08/01 21:22:51]

Ok.  I'll tighten this down.

+        childTreeWalkState.setForceCheckForPaintInvalidation();
     RenderObject::invalidateTreeIfNeeded(childTreeWalkState);
 }
 
-void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState, const RenderLayerModelObject& newPaintInvalidationContainer)
+bool RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState, const RenderLayerModelObject& newPaintInvalidationContainer)
 {
     const LayoutRect oldPaintInvalidationRect = previousPaintInvalidationRect();
     const LayoutPoint oldPositionFromPaintInvalidationContainer = previousPositionFromPaintInvalidationContainer();
@@ -1584,7 +1586,7 @@ void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInval
     // issue paint invalidations. We can then skip issuing of paint invalidations for the child
     // renderers as they'll be covered by the RenderView.
     if (view()->doingFullPaintInvalidation())
-        return;
+        return false;
 
     if ((onlyNeededPositionedMovementLayout() && compositingState() != PaintsIntoOwnBacking)
         || (shouldDoFullPaintInvalidationIfSelfPaintingLayer()
@@ -1593,12 +1595,13 @@ void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInval
         setShouldDoFullPaintInvalidation(true, MarkOnlyThis);
     }
 
-    if (!RenderObject::invalidatePaintIfNeeded(newPaintInvalidationContainer, oldPaintInvalidationRect, oldPositionFromPaintInvalidationContainer, paintInvalidationState))
+    bool didFullyInvalidatePaint = RenderObject::invalidatePaintIfNeeded(newPaintInvalidationContainer, oldPaintInvalidationRect, oldPositionFromPaintInvalidationContainer, paintInvalidationState);
+    if (!didFullyInvalidatePaint)
         invalidatePaintForOverflowIfNeeded();
 
     // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
-    if (enclosingLayer()) {
-        if (RenderLayerScrollableArea* area = enclosingLayer()->scrollableArea()) {
+    if (RenderLayer* layer = enclosingLayer()) {
+        if (RenderLayerScrollableArea* area = layer->scrollableArea()) {

[Julien - ping for review, 2014/08/01 21:20:01]

I wouldn't touch this, we spotted that this code doesn't seem right:
enclosingLayer() can repeatedly return the same RenderLayer in a subtree leading
to unneeded invalidations. We will change or refactor this code anyway.

[abarth-chromium, 2014/08/01 21:22:51]

ok

             if (area->hasVerticalBarDamage())
                 invalidatePaintRectangle(area->verticalBarDamage());
             if (area->hasHorizontalBarDamage())
@@ -1606,6 +1609,8 @@ void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInval
             area->resetScrollbarDamage();
         }
     }
+
+    return didFullyInvalidatePaint;
 }
 
 bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset, ContentsClipBehavior contentsClipBehavior)