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| author | Richard Biener <rguenther@suse.de> | 2016-09-27 12:56:38 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2016-09-27 12:56:38 +0000 |
| commit | 59896334f97c1d58c221d2975e33abccd0d331d5 (patch) | |
| tree | 98081d1a890b16cf38fe47a5ae0e7aa4b27bb30d /gcc/tree-ssa-sccvn.c | |
| parent | 4e7e89e8c9acdbffa6546d5e6056c7b81238c88f (diff) | |
| download | gcc-59896334f97c1d58c221d2975e33abccd0d331d5.zip gcc-59896334f97c1d58c221d2975e33abccd0d331d5.tar.gz gcc-59896334f97c1d58c221d2975e33abccd0d331d5.tar.bz2 | |
re PR tree-optimization/77745 (Inconsistent application of aliasing rules)
2016-09-27 Richard Biener <rguenther@suse.de>
PR tree-optimization/77745
* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
When removing redundant stores make sure to check compatibility
of the TBAA state for downstream accesses.
* tree-ssa-sccvn.c (visit_reference_op_store): Likewise for when
value-numbering virtual operands for store matches.
* g++.dg/torture/pr77745.C: New testcase.
From-SVN: r240534
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 7f44ec8..94fd66a 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -3599,13 +3599,21 @@ visit_reference_op_store (tree lhs, tree op, gimple *stmt) Otherwise, the vdefs for the store are used when inserting into the table, since the store generates a new memory state. */ - result = vn_reference_lookup (lhs, vuse, VN_NOWALK, NULL, false); - + result = vn_reference_lookup (lhs, vuse, VN_NOWALK, &vnresult, false); if (result) { if (TREE_CODE (result) == SSA_NAME) result = SSA_VAL (result); resultsame = expressions_equal_p (result, op); + if (resultsame) + { + /* If the TBAA state isn't compatible for downstream reads + we cannot value-number the VDEFs the same. */ + alias_set_type set = get_alias_set (lhs); + if (vnresult->set != set + && ! alias_set_subset_of (set, vnresult->set)) + resultsame = false; + } } if ((!result || !resultsame) |