It seems like this was accidentally dropped, breaking all a16 image
intrinsics for gfx10. This fixes failing/asserting during
lowering. With the feature added, the selected instruction fails the
verifier. Guess at how to fix this, which seems to have confused the
dword and component counts.
Duplicate the test and generate the checks since I know very little
about how these are really supposed to operate.
Could you add it right to the FeatureGFX10 maybe?