From 1967fd8f2197f2b0334ab0fbc26abc3d9efe56c9 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 3 Nov 2021 13:26:48 +0100 Subject: tree-optimization/102970 - remap cliques when translating over backedges The following makes sure to remap (or rather drop for simplicity) dependence info encoded in MR_DEPENDENCE_CLIQUE when PRE PHI translation translates a reference over a backedge since that ends up interleaving two different loop iterations which boils down to two different inline copies. 2021-11-03 Richard Biener PR tree-optimization/102970 * tree-ssa-pre.c (phi_translate_1): Drop clique and base when translating a MEM_REF over a backedge. * g++.dg/opt/pr102970.C: New testcase. --- gcc/tree-ssa-pre.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'gcc/tree-ssa-pre.c') diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c index 1cc1aae..dc55d86 100644 --- a/gcc/tree-ssa-pre.c +++ b/gcc/tree-ssa-pre.c @@ -1588,6 +1588,21 @@ phi_translate_1 (bitmap_set_t dest, newoperands.release (); return NULL; } + /* When we translate a MEM_REF across a backedge and we have + restrict info that's not from our functions parameters + we have to remap it since we now may deal with a different + instance where the dependence info is no longer valid. + See PR102970. Note instead of keeping a remapping table + per backedge we simply throw away restrict info. */ + if ((newop.opcode == MEM_REF + || newop.opcode == TARGET_MEM_REF) + && newop.clique > 1 + && (e->flags & EDGE_DFS_BACK)) + { + newop.clique = 0; + newop.base = 0; + changed = true; + } if (!changed) continue; if (!newoperands.exists ()) -- cgit v1.1