Fall back on stencil clip when SW mask fails to allocate

Fall back on stencil clip when SW mask fails to allocate

When generating a SW clip mask, we didn't used to verify that the
pixels had been successfully allocated. This would obviously crash
when the allocation was not successful. This change checks the
allocation first, and falls back on a stencil clip when it doesn't
succeed.

BUG=656589
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2456153003

Committed: https://skia.googlesource.com/skia/+/3affdc1bcd881ccf031fe18c96a1de2b9439a393

[csmartdalton, 2016-10-27 22:45:06]

Description was changed from

==========
Fall back on stencil clip when SW mask fails to allocate

When generating a SW clip mask, we didn't used to verify that the
pixels had been successfully allocated. This would obviously crash
when the allocation was not successful. This change checks the
allocation first, and falls back on a stencil clip when it doesn't
succeed.

BUG=656589
==========

to

==========
Fall back on stencil clip when SW mask fails to allocate

When generating a SW clip mask, we didn't used to verify that the
pixels had been successfully allocated. This would obviously crash
when the allocation was not successful. This change checks the
allocation first, and falls back on a stencil clip when it doesn't
succeed.

BUG=656589
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2456153003
==========

[csmartdalton, 2016-10-27 22:47:35]

csmartdalton@google.com changed reviewers:
+ bsalomon@google.com

[csmartdalton, 2016-10-27 22:49:33]

csmartdalton@google.com changed reviewers:
+ hcm@google.com

[bsalomon, 2016-10-28 14:24:49]

lgtm w/ question about unsigned->signed change.

https://codereview.chromium.org/2456153003/diff/1/src/gpu/GrClipStackClip.cpp
File src/gpu/GrClipStackClip.cpp (right):

https://codereview.chromium.org/2456153003/diff/1/src/gpu/GrClipStackClip.cpp...
src/gpu/GrClipStackClip.cpp:389: builder[1] = SkToS16(bounds.fLeft) |
(SkToS16(bounds.fRight) << 16);
Do we expect these bounds to ever be negative? I think the SkToU16 will assert
that they are not.

[csmartdalton, 2016-10-28 16:50:30]

https://codereview.chromium.org/2456153003/diff/1/src/gpu/GrClipStackClip.cpp
File src/gpu/GrClipStackClip.cpp (right):

https://codereview.chromium.org/2456153003/diff/1/src/gpu/GrClipStackClip.cpp...
src/gpu/GrClipStackClip.cpp:389: builder[1] = SkToS16(bounds.fLeft) |
(SkToS16(bounds.fRight) << 16);
On 2016/10/28 14:24:49, bsalomon wrote:
> Do we expect these bounds to ever be negative? I think the SkToU16 will assert
> that they are not.

If you disable all types of clipping except for software, SkToU16 triggers an
assert. It's because clipped image filters can save a layer with negative
bounds. Honestly that feels like a bug to me though.

[csmartdalton, 2016-10-28 18:41:59]

The CQ bit was checked by csmartdalton@google.com

[csmartdalton, 2016-10-28 18:42:00]

The patchset sent to the CQ was uploaded after l-g-t-m from bsalomon@google.com
Link to the patchset: https://codereview.chromium.org/2456153003/#ps40001
(title: "Fall back on stencil clip when SW mask fails to allocate")

[commit-bot: I haz the power, 2016-10-28 18:42:03]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-28 19:01:12]

Description was changed from

==========
Fall back on stencil clip when SW mask fails to allocate

When generating a SW clip mask, we didn't used to verify that the
pixels had been successfully allocated. This would obviously crash
when the allocation was not successful. This change checks the
allocation first, and falls back on a stencil clip when it doesn't
succeed.

BUG=656589
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2456153003
==========

to

==========
Fall back on stencil clip when SW mask fails to allocate

When generating a SW clip mask, we didn't used to verify that the
pixels had been successfully allocated. This would obviously crash
when the allocation was not successful. This change checks the
allocation first, and falls back on a stencil clip when it doesn't
succeed.

BUG=656589
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2456153003

Committed:
https://skia.googlesource.com/skia/+/3affdc1bcd881ccf031fe18c96a1de2b9439a393
==========

[commit-bot: I haz the power, 2016-10-28 19:01:13]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/3affdc1bcd881ccf031fe18c96a1de2b9439a393