glasm: Implement SetAttribute ViewportMask

src/shader_recompiler/backend/glasm/emit_glasm.cpp

@@ -286,7 +286,8 @@ void SetupOptions(const IR::Program& program, const Profile& profile,
     if (info.uses_sparse_residency) {
         header += "OPTION EXT_sparse_texture2;";
     }
-    if ((info.stores_viewport_index || info.stores_layer) && stage != Stage::Geometry) {
+    if (((info.stores_viewport_index || info.stores_layer) && stage != Stage::Geometry) ||
+        info.stores_viewport_mask) {
         if (profile.support_viewport_index_layer_non_geometry) {
             header += "OPTION NV_viewport_array2;";
         }

src/shader_recompiler/backend/glasm/emit_glasm_context_get_set.cpp

@@ -157,6 +157,14 @@ void EmitSetAttribute(EmitContext& ctx, IR::Attribute attr, ScalarF32 value,
                         "Viewport stored outside of geometry shader not supported by device");
         }
         break;
+    case IR::Attribute::ViewportMask:
+        // NV_viewport_array2 is required to access result.viewportmask, regardless of shader stage.
+        if (ctx.profile.support_viewport_index_layer_non_geometry) {
+            ctx.Add("MOV.F result.viewportmask[0].x,{};", value);
+        } else {
+            LOG_WARNING(Shader_GLASM, "Device does not support storing to ViewportMask");
+        }
+        break;
     case IR::Attribute::PointSize:
         ctx.Add("MOV.F result.pointsize.x,{};", value);
         break;