Hi Nicolai,
I think there is a simpler way to do this. Instead of going through
update_shaders, we can just set some bit in a user data SGPR e.g.
SI_SGPR_VS_STATE_BITS[1] and the vertex shader can clear gl_BaseVertex
based on that bit. There is no performance concern due to additional
instructions
From: Nicolai Hähnle
gl_BaseVertex is supposed to be 0 in non-indexed draws. Unfortunately, the
way they're implemented, the VGT always generates indices starting at 0,
and the VS prolog adds the start index.
There's a VGT_INDX_OFFSET register which causes the VGT to start at a
driver-defined in
