diff options
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 39 |
1 files changed, 36 insertions, 3 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index a49e7f6..cee3d73 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -6374,6 +6374,7 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs, vn_valueize = rpo_vn_valueize; /* Initialize the unwind state and edge/BB executable state. */ + bool need_max_rpo_iterate = false; for (int i = 0; i < n; ++i) { basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]); @@ -6388,11 +6389,14 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs, if (e->flags & EDGE_DFS_BACK) has_backedges = true; e->flags &= ~EDGE_EXECUTABLE; - if (e == entry) + if (iterate || e == entry) continue; if (bb_to_rpo[e->src->index] > i) - rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo, - bb_to_rpo[e->src->index]); + { + rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo, + bb_to_rpo[e->src->index]); + need_max_rpo_iterate = true; + } else rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo, @@ -6403,6 +6407,35 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs, entry->flags |= EDGE_EXECUTABLE; entry->dest->flags |= BB_EXECUTABLE; + /* When there are irreducible regions the simplistic max_rpo computation + above for the case of backedges doesn't work and we need to iterate + until there are no more changes. */ + unsigned nit = 0; + while (need_max_rpo_iterate) + { + nit++; + need_max_rpo_iterate = false; + for (int i = 0; i < n; ++i) + { + basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]); + edge e; + edge_iterator ei; + FOR_EACH_EDGE (e, ei, bb->preds) + { + if (e == entry) + continue; + int max_rpo = MAX (rpo_state[i].max_rpo, + rpo_state[bb_to_rpo[e->src->index]].max_rpo); + if (rpo_state[i].max_rpo != max_rpo) + { + rpo_state[i].max_rpo = max_rpo; + need_max_rpo_iterate = true; + } + } + } + } + statistics_histogram_event (cfun, "RPO max_rpo iterations", nit); + /* As heuristic to improve compile-time we handle only the N innermost loops and the outermost one optimistically. */ if (iterate) |