pco: run dce pass until no more progress is made

Signed-off-by: Simon Perretta <simon.perretta@imgtec.com>
Acked-by: Frank Binns <frank.binns@imgtec.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33998>

src/imagination/pco/pco_ir.c

@@ -28,7 +28,13 @@ void pco_process_ir(pco_ctx *ctx, pco_shader *shader)
 
    PCO_PASS(_, shader, pco_const_imms);
    PCO_PASS(_, shader, pco_opt);
-   PCO_PASS(_, shader, pco_dce);
+
+   bool progress;
+   do {
+      progress = false;
+      PCO_PASS(progress, shader, pco_dce);
+   } while (progress);
+
    /* TODO: schedule after RA instead as e.g. vecs may no longer be the first
     * time a drc result is used.
     */