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| author | Jakub Jelinek <jakub@redhat.com> | 2017-12-15 15:37:52 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@gcc.gnu.org> | 2017-12-15 15:37:52 +0100 |
| commit | e7425c18b5af5a12f68bde8b5f30adf02a774536 (patch) | |
| tree | 244e650451af7f181109c73ce6cd80058234b774 /gcc/fold-const.c | |
| parent | a72610d4320925787d635cb4ddb8a40967e05bc3 (diff) | |
| download | gcc-e7425c18b5af5a12f68bde8b5f30adf02a774536.zip gcc-e7425c18b5af5a12f68bde8b5f30adf02a774536.tar.gz gcc-e7425c18b5af5a12f68bde8b5f30adf02a774536.tar.bz2 | |
re PR tree-optimization/83269 (Wrong constant folding)
PR tree-optimization/83269
* fold-const.c (fold_binary_loc): Perform (-A) - B -> (-B) - A
subtraction in arg0's type if type is signed and arg0 is unsigned.
Formatting fix.
* gcc.c-torture/execute/pr83269.c: New test.
From-SVN: r255697
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 0f11076..9fc69e8 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -9098,8 +9098,8 @@ expr_not_equal_to (tree t, const wide_int &w) return NULL_TREE. */ tree -fold_binary_loc (location_t loc, - enum tree_code code, tree type, tree op0, tree op1) +fold_binary_loc (location_t loc, enum tree_code code, tree type, + tree op0, tree op1) { enum tree_code_class kind = TREE_CODE_CLASS (code); tree arg0, arg1, tem; @@ -9769,10 +9769,17 @@ fold_binary_loc (location_t loc, /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */ if (TREE_CODE (arg0) == NEGATE_EXPR - && negate_expr_p (op1)) - return fold_build2_loc (loc, MINUS_EXPR, type, - negate_expr (op1), - fold_convert_loc (loc, type, + && negate_expr_p (op1) + /* If arg0 is e.g. unsigned int and type is int, then this could + introduce UB, because if A is INT_MIN at runtime, the original + expression can be well defined while the latter is not. + See PR83269. */ + && !(ANY_INTEGRAL_TYPE_P (type) + && TYPE_OVERFLOW_UNDEFINED (type) + && ANY_INTEGRAL_TYPE_P (TREE_TYPE (arg0)) + && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0)))) + return fold_build2_loc (loc, MINUS_EXPR, type, negate_expr (op1), + fold_convert_loc (loc, type, TREE_OPERAND (arg0, 0))); /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to |