Mesa (master): spirv: Handle OOB vector extract operations

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Module: Mesa
Branch: master
Commit: 380bf556bfe34357f802dc49e1e104dc8fdf951a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=380bf556bfe34357f802dc49e1e104dc8fdf951a

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Thu Apr  9 16:44:33 2020 -0500

spirv: Handle OOB vector extract operations

We use vtn_vector_extract to handle vector component level derefs.  This
makes us gracefully handle the case where your vector component is OOB
and give you an undef.  The SPIR-V working group is still working out
whether or not this is technically legal but it's very little code for
us to handle it so we may as well.

Cc: mesa-stable at lists.freedesktop.org
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4495>

---

 src/compiler/spirv/spirv_to_nir.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 3ebe85e46ab..e0e8fdba27c 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -3314,7 +3314,10 @@ vtn_ssa_transpose(struct vtn_builder *b, struct vtn_ssa_value *src)
 nir_ssa_def *
 vtn_vector_extract(struct vtn_builder *b, nir_ssa_def *src, unsigned index)
 {
-   return nir_channel(&b->nb, src, index);
+   if (index > src->num_components)
+      return nir_ssa_undef(&b->nb, src->num_components, src->bit_size);
+   else
+      return nir_channel(&b->nb, src, index);
 }
 
 nir_ssa_def *