Mesa (staging/22.1): vulkan/nir: Don't remove dead XFB outputs

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Module: Mesa
Branch: staging/22.1
Commit: 5a9ef84f103a0ace6eacb010547a781cefdc713a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=5a9ef84f103a0ace6eacb010547a781cefdc713a

Author: Jason Ekstrand <jason.ekstrand at collabora.com>
Date:   Wed Jul 20 13:45:45 2022 -0500

vulkan/nir: Don't remove dead XFB outputs

Fixes: 21b405fbbc53 ("vulkan: Add a vk_shader_module_to_nir() helper")
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17644>
(cherry picked from commit bd93d6f69373cbc9dc5d32fbde1dd4a119a307c9)

---

 .pick_status.json           |  2 +-
 src/vulkan/runtime/vk_nir.c | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index f7a6e00f750..0717b7e4f8e 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -2731,7 +2731,7 @@
         "description": "vulkan/nir: Don't remove dead XFB outputs",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "21b405fbbc539666f83bd881011c9d7333d6b060"
     },
diff --git a/src/vulkan/runtime/vk_nir.c b/src/vulkan/runtime/vk_nir.c
index e8c05697585..327efdfe42c 100644
--- a/src/vulkan/runtime/vk_nir.c
+++ b/src/vulkan/runtime/vk_nir.c
@@ -64,6 +64,16 @@ spirv_nir_debug(void *private_data,
    }
 }
 
+static bool
+is_not_xfb_output(nir_variable *var, void *data)
+{
+   if (var->data.mode != nir_var_shader_out)
+      return true;
+
+   return !var->data.explicit_xfb_buffer &&
+          !var->data.explicit_xfb_stride;
+}
+
 nir_shader *
 vk_spirv_to_nir(struct vk_device *device,
                 uint32_t *spirv_data, size_t spirv_size_B,
@@ -129,10 +139,13 @@ vk_spirv_to_nir(struct vk_device *device,
    NIR_PASS_V(nir, nir_split_var_copies);
    NIR_PASS_V(nir, nir_split_per_member_structs);
 
+   nir_remove_dead_variables_options dead_vars_opts = {
+      .can_remove_var = is_not_xfb_output,
+   };
    NIR_PASS_V(nir, nir_remove_dead_variables,
               nir_var_shader_in | nir_var_shader_out | nir_var_system_value |
               nir_var_shader_call_data | nir_var_ray_hit_attrib,
-              NULL);
+              &dead_vars_opts);
 
    NIR_PASS_V(nir, nir_propagate_invariant, false);