Calling this lower pass twice in a row would cause spurious
set_vertex_and_primitive_count(0, undef) intrinsics after the proper
set_vertex_and_primitive_count intrinsic. This pretty much turns any
geometry shader into garbage.
Fix this by treating nir_intrinsic_emit_vertex_with_counter and
nir_intrinsic_end_primitive_with_counter just like the non-_with_counter
versions. If no blocks would need set_vertex_and_primitive_count
intrinsics added, exit the pass before doing any work. This prevents
the need for DCE to do extra clean up later.
Since this pass is potentially called multiple times via multiple
invocations of a finalize_nir callback, it is (hypothetically?) possible
that control flow could be changed to add new blocks that need this
intrinsic. The check implemented in this commit should be robust
against that possibility.
v2: Add a_block_needs_set_vertex_and_primitive_count. Suggested by
Timur.
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12802>
Ian Romanick
7956a701d8