This fixes an old FIXME, where (workitem ID X) / (wavefrront size) would
never be marked uniform if it was possible that there would be Y and Z
dimensions. Now, so long as the required size of the X dimension is a
power of 2, dividing that dimension by the wavefront size creates a
uniform value.
Furthermore, if the required launch size of the X dimension is a power
of 2 that's at least the wavefront size, the Y and Z workitem IDs are
now marked uniform.
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Co-authored-by: Matt Arsenault <arsenm2@gmail.com>
9470113495