Mesa (master): st/program: use nir_lower_clip_disable instead of nir_lower_clip_vs conditionally

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Module: Mesa
Branch: master
Commit: a79ca675f3d61d22853657831d8b1c3a6b27e9fa
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a79ca675f3d61d22853657831d8b1c3a6b27e9fa

Author: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Date:   Wed Jun 17 09:40:51 2020 -0400

st/program: use nir_lower_clip_disable instead of nir_lower_clip_vs conditionally

if the shader already outputs gl_ClipDistance, nir_lower_clip_vs will create
duplicate variables when what we want is to just change the existing values

Reviewed-by: Erik Faye-Lund <erik.faye-lund at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5529>

---

 src/mesa/state_tracker/st_program.c | 38 +++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

diff --git a/src/mesa/state_tracker/st_program.c b/src/mesa/state_tracker/st_program.c
index cb9fcfdbdd6..d0e16cf16a8 100644
--- a/src/mesa/state_tracker/st_program.c
+++ b/src/mesa/state_tracker/st_program.c
@@ -716,24 +716,30 @@ st_create_vp_variant(struct st_context *st,
                                               PIPE_CAP_NIR_COMPACT_ARRAYS);
 
          bool use_eye = st->ctx->_Shader->CurrentProgram[MESA_SHADER_VERTEX] != NULL;
-         gl_state_index16 clipplane_state[MAX_CLIP_PLANES][STATE_LENGTH];
-         for (int i = 0; i < MAX_CLIP_PLANES; ++i) {
-            if (use_eye) {
-               clipplane_state[i][0] = STATE_CLIPPLANE;
-               clipplane_state[i][1] = i;
-            } else {
-               clipplane_state[i][0] = STATE_INTERNAL;
-               clipplane_state[i][1] = STATE_CLIP_INTERNAL;
-               clipplane_state[i][2] = i;
+         struct nir_shader *nir = state.ir.nir;
+
+         if (nir->info.outputs_written & VARYING_BIT_CLIP_DIST0)
+            NIR_PASS_V(state.ir.nir, nir_lower_clip_disable, key->lower_ucp);
+         else {
+            gl_state_index16 clipplane_state[MAX_CLIP_PLANES][STATE_LENGTH];
+            for (int i = 0; i < MAX_CLIP_PLANES; ++i) {
+               if (use_eye) {
+                  clipplane_state[i][0] = STATE_CLIPPLANE;
+                  clipplane_state[i][1] = i;
+               } else {
+                  clipplane_state[i][0] = STATE_INTERNAL;
+                  clipplane_state[i][1] = STATE_CLIP_INTERNAL;
+                  clipplane_state[i][2] = i;
+               }
+               _mesa_add_state_reference(params, clipplane_state[i]);
             }
-            _mesa_add_state_reference(params, clipplane_state[i]);
-         }
 
-         NIR_PASS_V(state.ir.nir, nir_lower_clip_vs, key->lower_ucp,
-                    true, can_compact, clipplane_state);
-         NIR_PASS_V(state.ir.nir, nir_lower_io_to_temporaries,
-                    nir_shader_get_entrypoint(state.ir.nir), true, false);
-         NIR_PASS_V(state.ir.nir, nir_lower_global_vars_to_local);
+            NIR_PASS_V(state.ir.nir, nir_lower_clip_vs, key->lower_ucp,
+                       true, can_compact, clipplane_state);
+            NIR_PASS_V(state.ir.nir, nir_lower_io_to_temporaries,
+                       nir_shader_get_entrypoint(state.ir.nir), true, false);
+            NIR_PASS_V(state.ir.nir, nir_lower_global_vars_to_local);
+         }
          finalize = true;
       }