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| author | Richard Biener <rguenther@suse.de> | 2015-10-29 14:10:31 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2015-10-29 14:10:31 +0000 |
| commit | 55db37536fcff75d42cb852e3c822f9f3fb5f04f (patch) | |
| tree | af44e27e3907d99f2751ff4e4aa9f9a2f0ece228 /gcc/fold-const.c | |
| parent | 957060b5c5d272296ccd00ebdb5179ef25123fb5 (diff) | |
| download | gcc-55db37536fcff75d42cb852e3c822f9f3fb5f04f.zip gcc-55db37536fcff75d42cb852e3c822f9f3fb5f04f.tar.gz gcc-55db37536fcff75d42cb852e3c822f9f3fb5f04f.tar.bz2 | |
re PR middle-end/68142 (unsafe association of multiplication)
2015-10-29 Richard Biener <rguenther@suse.de>
PR middle-end/68142
* fold-const.c (extract_muldiv_1): Avoid introducing undefined
overflow.
* c-c++-common/ubsan/pr68142.c: New testcase.
From-SVN: r229528
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 298c520..26fd735 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -6008,8 +6008,17 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type, or (for divide and modulus) if it is a multiple of our constant. */ if (code == MULT_EXPR || wi::multiple_of_p (t, c, TYPE_SIGN (type))) - return const_binop (code, fold_convert (ctype, t), - fold_convert (ctype, c)); + { + tree tem = const_binop (code, fold_convert (ctype, t), + fold_convert (ctype, c)); + /* If the multiplication overflowed to INT_MIN then we lost sign + information on it and a subsequent multiplication might + spuriously overflow. See PR68142. */ + if (TREE_OVERFLOW (tem) + && wi::eq_p (tem, wi::min_value (TYPE_PRECISION (ctype), SIGNED))) + return NULL_TREE; + return tem; + } break; CASE_CONVERT: case NON_LVALUE_EXPR: |