Mesa (main): nir/opt_access: fix getting variables in presence of similar bindings/desc

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Module: Mesa
Branch: main
Commit: 1b1c726ca91dff781363b1b0980b47ca18f86a76
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=1b1c726ca91dff781363b1b0980b47ca18f86a76

Author: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Date:   Fri May  7 15:50:24 2021 +0200

nir/opt_access: fix getting variables in presence of similar bindings/desc

It's perfectly legal to declare multiple SSBOs that point to the same
binding/descriptor_set with different access mask. Currently, it will
always get the first one in the list that matches binding/desc_set
regardless of the access mask, but other variables might have different
access mask.

Fix this by being conservative if another variable uses the same
binding/desc_set because we can't get it reliably without adding
a new field to vulkan_resource_index.

This fixes rendering issues in Resident Evil Village with vkd3d-proton.
This bug has been uncovered by ("spirv: Don't remove variables used by
resource indexing intrinsics") because variables are no longer removed

No fossils-db changes.

Cc: 21.1 mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10692>

---

 src/compiler/nir/nir.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/compiler/nir/nir.c b/src/compiler/nir/nir.c
index 5e81447c039..9d7cb35765b 100644
--- a/src/compiler/nir/nir.c
+++ b/src/compiler/nir/nir.c
@@ -2411,6 +2411,9 @@ nir_binding nir_chase_binding(nir_src rsrc)
 
 nir_variable *nir_get_binding_variable(nir_shader *shader, nir_binding binding)
 {
+   nir_variable *binding_var = NULL;
+   unsigned count = 0;
+
    if (!binding.success)
       return NULL;
 
@@ -2418,9 +2421,17 @@ nir_variable *nir_get_binding_variable(nir_shader *shader, nir_binding binding)
       return binding.var;
 
    nir_foreach_variable_with_modes(var, shader, nir_var_mem_ubo | nir_var_mem_ssbo) {
-      if (var->data.descriptor_set == binding.desc_set && var->data.binding == binding.binding)
-         return var;
+      if (var->data.descriptor_set == binding.desc_set && var->data.binding == binding.binding) {
+         binding_var = var;
+         count++;
+      }
    }
 
-   return NULL;
+   /* Be conservative if another variable is using the same binding/desc_set
+    * because the access mask might be different and we can't get it reliably.
+    */
+   if (count > 1)
+      return NULL;
+
+   return binding_var;
 }