We had previously encountered a driver bug on Mali Valhall GPUs where
invalidating render targets once they are no longer required results
in rendering artefacts. This invalidation was purely an optimization,
which probably doesn't help much on Mali architecture anyway, so we
can workaround the bug by skipping the invalidation. See bug 1787520
for details.
The latest Mali Valhall GPUs are also affected. This patch therefore
applies the workaround to *all* "Mali-G" models apart from a list of
known working ones. This means we will avoid hitting this issue again
when the next generation of GPUs are released. Once ARM move on to the
next family we can see whether it is still affected and update the
code accordingly if required.
Differential Revision: https://phabricator.services.mozilla.com/D194063
cf198fa5f7