https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69609
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> --- Created attachment 37718 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37718&action=edit patch The attached patch implements a simple caching mechanism which reduces time (checking enabled but with -fno-checking) from reorder blocks : 260.53 (80%) usr 0.37 (27%) sys 261.80 (80%) wall 432597 kB (58%) ggc TOTAL : 323.98 1.38 328.14 745950 kB to reorder blocks : 135.46 (71%) usr 0.12 ( 9%) sys 135.70 (71%) wall 432597 kB (58%) ggc TOTAL : 190.60 1.29 192.10 745950 kB I'm going to see whether bb_to_key is still the issue (the resetting of cached key could be made smarter, updating the value from the edge that changed). Still the above is a reasonable improvement given we have FOR_EACH_EDGE (e, ei, bb->succs) { if (e == best_edge || e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun) || bb_visited_trace (e->dest)) continue; key = bb_to_key (e->dest); where bb_to_key does FOR_EACH_EDGE (e, ei, bb->preds). Yup. Even with the patch bb_to_key is still taking 67% of the compile time (according to perf).
