Mesa (master): nir/deref: Don't try to compare derefs containing casts

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Module: Mesa
Branch: master
Commit: 611f654fcf715364b65ca690c0521c3e3038824f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=611f654fcf715364b65ca690c0521c3e3038824f

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Fri Jul 24 20:27:37 2020 -0500

nir/deref: Don't try to compare derefs containing casts

One day, we may want copy_prop_vars or other passes to be able to see
through certain types of casts such as when someone casts a uint64_t to
a uvec2.  However, for now we should just avoid casts all together.

Fixes: d8e3edb784d3a "nir/deref: Support casts and ptr_as_array in..."
Tested-by: Jesse Natalie <jenatali at microsoft.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6072>

---

 src/compiler/nir/nir_deref.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c
index dca76210f8f..59805cdbd01 100644
--- a/src/compiler/nir/nir_deref.c
+++ b/src/compiler/nir/nir_deref.c
@@ -516,8 +516,8 @@ nir_compare_deref_paths(nir_deref_path *a_path,
    }
 
    /* We're at either the tail or the divergence point between the two deref
-    * paths.  Look to see if either contains a ptr_as_array deref.  It it
-    * does we don't know how to safely make any inferences.  Hopefully,
+    * paths.  Look to see if either contains cast or a ptr_as_array deref.  If
+    * it does we don't know how to safely make any inferences.  Hopefully,
     * nir_opt_deref will clean most of these up and we can start inferring
     * things again.
     *
@@ -527,11 +527,13 @@ nir_compare_deref_paths(nir_deref_path *a_path,
     * different constant indices.
     */
    for (nir_deref_instr **t_p = a_p; *t_p; t_p++) {
-      if ((*t_p)->deref_type == nir_deref_type_ptr_as_array)
+      if ((*t_p)->deref_type == nir_deref_type_cast ||
+          (*t_p)->deref_type == nir_deref_type_ptr_as_array)
          return nir_derefs_may_alias_bit;
    }
    for (nir_deref_instr **t_p = b_p; *t_p; t_p++) {
-      if ((*t_p)->deref_type == nir_deref_type_ptr_as_array)
+      if ((*t_p)->deref_type == nir_deref_type_cast ||
+          (*t_p)->deref_type == nir_deref_type_ptr_as_array)
          return nir_derefs_may_alias_bit;
    }