[Mesa-dev] [PATCH] spirv: Implicitly set missing NonWriteable decoration

[Jason Ekstrand]

This works around rendering issues in Skyrim caused by DXVK missing a
decoration.
---
 src/compiler/spirv/vtn_variables.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index 574f422ceab..24b278e17fd 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -1752,8 +1752,24 @@ vtn_create_variable(struct vtn_builder *b, struct vtn_value *val,
       var->var->data.descriptor_set = var->descriptor_set;
       var->var->data.index = var->input_attachment_index;
 
-      if (glsl_type_is_image(without_array->type))
+      if (glsl_type_is_image(without_array->type)) {
          var->var->data.image.format = without_array->image_format;
+
+         /* The requirement that the NonReadable decoration be set was added
+          * as a clarification to the Vulkan spec in version 1.1.76 and not
+          * all apps respect it.  Setting it implicitly inside spirv_to_nir
+          * fixes rendering issues in Skyrim on DXVK as of June 27, 2018.
+          */
+         if (var->var->data.image.format == 0 &&
+             !var->var->data.image.write_only &&
+             !b->options->caps.image_read_without_format) {
+            vtn_warn("Image variable created an unknown format and without "
+                     "the NonReadable decoration set but the driver does not "
+                     "support shaderStorageImageReadWithoutFormat.  Setting "
+                     "the decoration implicitly to work around the problem.");
+            var->var->data.image.write_only = true;
+         }
+      }
    }
 
    if (var->mode == vtn_variable_mode_local) {
-- 
2.17.1