nir: call nir_metadata_preserve in nir_vectorize_tess_levels

This is necessary to use this pass with the NIR_PASS() macro.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12448>

src/compiler/nir/nir_lower_io_to_vector.c

@@ -677,6 +677,11 @@ nir_vectorize_tess_levels_impl(nir_function_impl *impl)
       }
    }
 
+   if (progress)
+      nir_metadata_preserve(impl, nir_metadata_block_index | nir_metadata_dominance);
+   else
+      nir_metadata_preserve(impl, nir_metadata_all);
+
    return progress;
 }