For gfx10 gradient (g16) and address (a16) can be independent. Previous
implementation assumed that a16 implied g16.
There are some other changes that fix the verification (as well as asm/disasm)
that are required for the included test to pass - the XFAIL will be removed in
those changes.
"16 bit addresses need 16 bit addresses ..." reads wrong. But anyway maybe combine these two cases into a single "if (IsA16 != IsG16)" with an appropriately general error message?