Module: Mesa
Branch: main
Commit: 56a9aad4010ff9f2c0afcadec0ac61a6274de0a3
URL:    
http://cgit.freedesktop.org/mesa/mesa/commit/?id=56a9aad4010ff9f2c0afcadec0ac61a6274de0a3

Author: Karol Herbst <[email protected]>
Date:   Wed Feb 22 04:40:24 2023 +0100

nir/deref: don't replace casts with deref_struct if we'd lose the stride

The result might be used in a deref_ptr_as_array, which requires a proper
stride within lower_explicit_io. If we'd lose that information or end up
with a different stride don't execute this optimization.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/8289
Fixes: b779baa9bf95 ("nir/deref: fix struct wrapper casts. (v3)")
Signed-off-by: Karol Herbst <[email protected]>
Reviewed-by: Faith Ekstrand <[email protected]>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21458>

---

 src/compiler/nir/nir_deref.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c
index 3de401d9853..9289b23f6a2 100644
--- a/src/compiler/nir/nir_deref.c
+++ b/src/compiler/nir/nir_deref.c
@@ -1143,7 +1143,12 @@ opt_replace_struct_wrapper_cast(nir_builder *b, 
nir_deref_instr *cast)
    if (glsl_get_struct_field_offset(parent->type, 0) != 0)
       return false;
 
-   if (cast->type != glsl_get_struct_field(parent->type, 0))
+   const struct glsl_type *field_type = glsl_get_struct_field(parent->type, 0);
+   if (cast->type != field_type)
+      return false;
+
+   /* we can't drop the stride information */
+   if (cast->cast.ptr_stride != glsl_get_explicit_stride(field_type))
       return false;
 
    nir_deref_instr *replace = nir_build_deref_struct(b, parent, 0);

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