ac/nir: run nir_lower_vars_to_ssa after nir_lower_task_shader

nir_lower_task_shader does nir_lower_returns, so we need this if the
launch_mesh_workgroups was in control flow.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/13326
Backport-to: 25.1
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35411>

src/amd/common/nir/ac_nir_lower_taskmesh_io_to_mem.c

@@ -289,6 +289,9 @@ ac_nir_lower_task_outputs_to_mem(nir_shader *shader,
    };
    progress |= nir_lower_task_shader(shader, lower_ts_opt);
 
+   /* Needed after nir_lower_task_shader */
+   progress |= nir_lower_vars_to_ssa(shader);
+
    lower_tsms_io_state state = {
       .draw_entry_bytes = 16,
       .payload_entry_bytes = task_payload_entry_bytes,