Doesn't seem necessary anymore. I think this was mostly compensating for
not enabling WQM for texture sampling instructions.
v2: Add test coverage
Reviewed-by: Tom Stellard <tom@stellard.net>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228373 91177308-0d34-0410-b5e6-96231b3b80d8
