[SPIR-V] Vertex index writing to r0.x

src/xenia/ui/vulkan/vulkan_provider.cc

@@ -287,6 +287,12 @@ bool VulkanProvider::Initialize() {
     // Get physical device features and check if the needed ones are supported.
     ifn_.vkGetPhysicalDeviceFeatures(physical_device_current,
                                      &device_features_);
+    // Passing indices directly from guest memory, where they are big-endian; a
+    // workaround using fetch from shared memory for 32-bit indices that need
+    // swapping isn't implemented yet. Not supported only Qualcomm Adreno 4xx.
+    if (!device_features_.fullDrawIndexUint32) {
+      continue;
+    }
     // TODO(Triang3l): Make geometry shaders optional by providing compute
     // shader fallback (though that would require vertex shader stores).
     if (!device_features_.geometryShader) {