From 0df746afc50a47d1eb53a401e017c4373cf05641 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 21 Sep 2020 14:04:25 +0200 Subject: [PATCH] tree-optimization/97135 - fix dependence check in store-motion The following fixes a dependence check where in the particular place we cannot ignore self-dependences. 2020-09-21 Richard Biener PR tree-optimization/97135 * tree-ssa-loop-im.c (sm_seq_push_down): Do not ignore self-dependences. * gcc.dg/torture/pr97135.c: New testcase. --- gcc/testsuite/gcc.dg/torture/pr97135.c | 21 +++++++++++++++++++++ gcc/tree-ssa-loop-im.c | 8 +++++--- 2 files changed, 26 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr97135.c diff --git a/gcc/testsuite/gcc.dg/torture/pr97135.c b/gcc/testsuite/gcc.dg/torture/pr97135.c new file mode 100644 index 00000000000..223f4d05b85 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr97135.c @@ -0,0 +1,21 @@ +/* { dg-do run } */ + +long long e, *d = &e; +int a, b, c; + +int +main () +{ + for (; c <= 5; c++) + for (b = 0; b <= 5; b++) + { + for (a = 1; a <= 5; a++) + ; + *d = 0; + if (c) + break; + } + if (a != 6) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c index f87c287d742..139c7e76e66 100644 --- a/gcc/tree-ssa-loop-im.c +++ b/gcc/tree-ssa-loop-im.c @@ -2232,9 +2232,11 @@ sm_seq_push_down (vec &seq, unsigned ptr, unsigned *at) || (against.second == sm_other && against.from != NULL_TREE)) /* Found the tail of the sequence. */ break; - if (!refs_independent_p (memory_accesses.refs_list[new_cand.first], - memory_accesses.refs_list[against.first], - false)) + /* We may not ignore self-dependences here. */ + if (new_cand.first == against.first + || !refs_independent_p (memory_accesses.refs_list[new_cand.first], + memory_accesses.refs_list[against.first], + false)) /* ??? Prune new_cand from the list of refs to apply SM to. */ return false; std::swap (new_cand, against); -- 2.30.2