Mesa (master): nir/clip_disable: write 0s instead of undefs for disabled clip planes

[GitLab Mirror]

Module: Mesa
Branch: master
Commit: 1d23a88c6eb7502ea38e3e9d1a28b7df49c78e29
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1d23a88c6eb7502ea38e3e9d1a28b7df49c78e29

Author: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Date:   Thu Sep  3 10:25:24 2020 -0400

nir/clip_disable: write 0s instead of undefs for disabled clip planes

this should yield more reliable and ideally even correct results

Reviewed-by: Eric Anholt <eric at anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6563>

---

 src/compiler/nir/nir_lower_clip_disable.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/compiler/nir/nir_lower_clip_disable.c b/src/compiler/nir/nir_lower_clip_disable.c
index ae086459c0c..102eab58deb 100644
--- a/src/compiler/nir/nir_lower_clip_disable.c
+++ b/src/compiler/nir/nir_lower_clip_disable.c
@@ -30,7 +30,7 @@
 
 /**
  * This pass uses the enabled clip planes from the rasterizer state to rewrite
- * vertex shader store operations and store an undef to the corresponding gl_ClipDistance[n]
+ * vertex shader store operations and store a 0 to the corresponding gl_ClipDistance[n]
  * value if the plane is disabled
  */
 
@@ -45,7 +45,7 @@ recursive_if_chain(nir_builder *b, nir_deref_instr *deref, nir_ssa_def *value, u
       if (clip_plane_enable & (1 << start))
          nir_store_deref(b, deref, value, 1 << start);
       else
-         nir_store_deref(b, deref, nir_ssa_undef(b, 1, 32), 1 << start);
+         nir_store_deref(b, deref, nir_imm_int(b, 0), 1 << start);
       return;
    }
 
@@ -58,7 +58,7 @@ recursive_if_chain(nir_builder *b, nir_deref_instr *deref, nir_ssa_def *value, u
 }
 
 /* vulkan (and some drivers) provides no concept of enabling clip planes through api,
- * so we rewrite disabled clip planes to an undefined value in order to disable them
+ * so we rewrite disabled clip planes to a zero value in order to disable them
  */
 static bool
 lower_clip_plane_store(nir_intrinsic_instr *instr, unsigned clip_plane_enable, nir_builder *b)
@@ -84,7 +84,7 @@ lower_clip_plane_store(nir_intrinsic_instr *instr, unsigned clip_plane_enable, n
       if (clip_plane_enable & (1 << plane))
          return false;
 
-      nir_store_deref(b, deref, nir_ssa_undef(b, 1, 32), 1 << plane);
+      nir_store_deref(b, deref, nir_imm_int(b, 0), 1 << plane);
    } else {
       /* storing using a variable index */
       nir_ssa_def *index = nir_ssa_for_src(b, deref->arr.index, 1);