The compiler setup for these VF-uploaded attributes looks a little
cheesy with mixing system values and real VBO-sourced attributes. It
would be nice if we could just compute the ATTR[] map to GRF index up
front and use it at visit time instead of using ir->location in the
ATTR file. However, we don't know the reg_offset at
visit(ir_variable *) time, so we can't do the mapping that early.
Fixes piglit vertexid test.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Eric Anholt
1c65abb211