This change is required to enable PIX to reconstruct mesh shader output data correctly. Without knowing the thread id of the AS thread that launched the mesh shader threads, we don't know which probably-a-mesh to attribute each MS's output to.
This is a pass for PIX that adds instructions to write mesh shader output (vertices and indices) to a UAV for later ingestion by PIX in order to present a view of that output.
Jeff Noyle
John Porto
Xiang Li