From: Richard Biener <rguenther@suse.de>
To: gcc-patches@gcc.gnu.org
Subject: [PATCH] Some VN TLC
Date: Thu, 22 Sep 2022 09:10:14 +0200 (CEST) [thread overview]
Message-ID: <20220922071014.D15181346B@imap2.suse-dmz.suse.de> (raw)
The following was prompted by review of the patch introducing
equivalences to VN.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
* 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 74b8d8d18ef..85a7698f694 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)
--
2.35.3
reply other threads:[~2022-09-22 7:10 UTC|newest]
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