commit 0e3129d734212089f872f0e7de8f2537861a3f89
author jbroman <jbroman@chromium.org> Thu Mar 17 12:24:23 2016 -0700
committer Commit bot <commit-bot@chromium.org> Thu Mar 17 12:24:23 2016 -0700
tree a5c9e45f0166af306abd93da69bee65402501da7
parent c9a99872274ab63f2130caeccc75a2f52b8677a3

Fix pointer aliasing bug in SkImageFilter::computeFastBounds.

Since src and dst are explicitly allowed to alias (according to a comment in
SkPaint.h), it is problematic to have the first input filter mutate dst, since
we still need access to the previous value to provide to the other input
filters.

To resolve this, SkImageFilter::computeFastBounds makes a copy of src on the
stack, and passes that to its inputs instead.

Also add a unit test that would have detected the issue.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1800263002

Review URL: https://codereview.chromium.org/1800263002