commit 2aaa1564ad0620724eaf38d66cec85dafad4613e
author Alejandro Piñeiro <apinheiro@igalia.com> Tue Sep 15 23:53:14 2020 +0200
committer Alejandro Piñeiro <apinheiro@igalia.com> Wed Sep 16 23:24:28 2020 +0200
tree 46e31b62665593691ecab42b4c5d347a7c96e413
parent a51aa6feb4dab07e29b9834f7ad431cc0dd6f9fe

nir/lower_io: don't reduce range if parent length is zero

When handling arrays, range is increased based on the array size minus
one. But if such is zero, it has the effect of reducing the
range. Handle that case by returning the unknown range value.

v2:
  * Add missing braces.
  * Return unknown range in this case, instead of keeping the initial
    range.
v3: Simplify code, using existing "fail" label. (Jason)

Fixes the following using v3dv:
  dEQP-VK.graphicsfuzz.cov-simplify-clamp-max-itself

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6737>

src/compiler/nir/nir_lower_io.c

diff --git a/src/compiler/nir/nir_lower_io.c b/src/compiler/nir/nir_lower_io.c
index 52c22ad..986c4c0 100644
--- a/src/compiler/nir/nir_lower_io.c
+++ b/src/compiler/nir/nir_lower_io.c
@@ -982,10 +982,13 @@
             goto fail;
 
          if (deref->deref_type != nir_deref_type_array_wildcard &&
-             nir_src_is_const(deref->arr.index))
+             nir_src_is_const(deref->arr.index)) {
             base += stride * nir_src_as_uint(deref->arr.index);
-         else
+         } else {
+            if (glsl_get_length(parent->type) == 0)
+               goto fail;
             range += stride * (glsl_get_length(parent->type) - 1);
+         }
          break;
       }