nir: add lowering stage for user-clip-planes / clipdist

The vertex shader lowering adds calculation for CLIPDIST, if needed
(ie. user-clip-planes), and the frag shader lowering adds conditional
kills based on CLIPDIST value (which should be treated as a normal
interpolated varying by the driver).

Note that this won't quite do the right thing in the face of MSAA plus
user-clip-planes, since all the samples would be killed or not (rather
than potentially only a portion of them).  But it's better than no UCP
support at all for drivers that don't have this in hw.

Signed-off-by: Rob Clark <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index f64bb2837c3..916226791e6 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1839,6 +1839,9 @@ void nir_lower_system_values(nir_shader *shader);
 void nir_lower_tex_projector(nir_shader *shader);
 void nir_lower_idiv(nir_shader *shader);
 
+void nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables);
+void nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables);
+
 void nir_lower_atomics(nir_shader *shader);
 void nir_lower_to_source_mods(nir_shader *shader);