When using the BasicCompositor, CG prints many warnings complaining about null contexts. These contexts come from the UnboundnessFixer which tries to create a CGLayer with 0x0 size.

As an aside can you look into why were hitting the UnboundnessFixer with BasicCompositor? That suggests badness.

Comment on attachment 8349085 [details] [diff] [review] early exit if clip is empty Review of attachment 8349085 [details] [diff] [review]: ----------------------------------------------------------------- ::: gfx/2d/DrawTargetCG.cpp @@ +247,5 @@ > { > if (!IsOperatorBoundByMask(blend)) { > mClipBounds = CGContextGetClipBoundingBox(baseCg); > + if (CGRectIsEmpty(mClipBounds)) { > + return nullptr; I think we can just do return baseCG; here and not have to add all of the other checks.

(In reply to Jeff Muizelaar [:jrmuizel] from comment #1) > As an aside can you look into why were hitting the UnboundnessFixer with > BasicCompositor? That suggests badness. The DrawSurface call at http://hg.mozilla.org/mozilla-central/annotate/1ad9af3a2ab8/gfx/layers/RotatedBuffer.cpp#l150 passes has aOperator == OP_SOURCE from http://hg.mozilla.org/mozilla-central/annotate/1ad9af3a2ab8/gfx/layers/client/ContentClient.cpp#l652 .

Great idea.