From 41c7d2930a75eda3350956b6d9df9e571f9b494d Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 22 Sep 2022 09:08:47 +0200 Subject: [PATCH] Some VN TLC The following was prompted by review of the patch introducing equivalences to VN. * tree-ssa-sccvn.cc (can_track_predicate_on_edge): New function split out from ... (vn_nary_op_insert_pieces_predicated): ... here. --- gcc/tree-ssa-sccvn.cc | 43 +++++++++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 16 deletions(-) diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 74b8d8d..85a7698 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -4460,28 +4460,39 @@ vn_nary_op_insert_pieces (unsigned int length, enum tree_code code, return vn_nary_op_insert_into (vno1, valid_info->nary); } +/* Return whether we can track a predicate valid when PRED_E is executed. */ + +static bool +can_track_predicate_on_edge (edge pred_e) +{ + /* ??? As we are currently recording a basic-block index in + vn_pval.valid_dominated_by_p and using dominance for the + validity check we cannot track predicates on all edges. */ + if (single_pred_p (pred_e->dest)) + return true; + /* Never record for backedges. */ + if (pred_e->flags & EDGE_DFS_BACK) + return false; + /* When there's more than one predecessor we cannot track + predicate validity based on the destination block. The + exception is when all other incoming edges are backedges. */ + edge_iterator ei; + edge e; + int cnt = 0; + FOR_EACH_EDGE (e, ei, pred_e->dest->preds) + if (! dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) + cnt++; + return cnt == 1; +} + static vn_nary_op_t vn_nary_op_insert_pieces_predicated (unsigned int length, enum tree_code code, tree type, tree *ops, tree result, unsigned int value_id, edge pred_e) { - /* ??? Currently tracking BBs. */ - if (! single_pred_p (pred_e->dest)) - { - /* Never record for backedges. */ - if (pred_e->flags & EDGE_DFS_BACK) - return NULL; - edge_iterator ei; - edge e; - int cnt = 0; - /* Ignore backedges. */ - FOR_EACH_EDGE (e, ei, pred_e->dest->preds) - if (! dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) - cnt++; - if (cnt != 1) - return NULL; - } + if (!can_track_predicate_on_edge (pred_e)) + return NULL; if (dump_file && (dump_flags & TDF_DETAILS) /* ??? Fix dumping, but currently we only get comparisons. */ && TREE_CODE_CLASS (code) == tcc_comparison) -- 2.7.4