diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index e8ff1de..61801cb 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -443,7 +443,9 @@ negate_expr_p (tree t) case PLUS_EXPR: if (HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type)) - || HONOR_SIGNED_ZEROS (element_mode (type))) + || HONOR_SIGNED_ZEROS (element_mode (type)) + || (INTEGRAL_TYPE_P (type) + && ! TYPE_OVERFLOW_WRAPS (type))) return false; /* -(A + B) -> (-B) - A. */ if (negate_expr_p (TREE_OPERAND (t, 1)) @@ -457,12 +459,23 @@ negate_expr_p (tree t) /* We can't turn -(A-B) into B-A when we honor signed zeros. */ return !HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type)) && !HONOR_SIGNED_ZEROS (element_mode (type)) + && (! INTEGRAL_TYPE_P (type) + || TYPE_OVERFLOW_WRAPS (type)) && reorder_operands_p (TREE_OPERAND (t, 0), TREE_OPERAND (t, 1)); case MULT_EXPR: - if (TYPE_UNSIGNED (TREE_TYPE (t))) - break; + if (TYPE_UNSIGNED (type)) + break; + /* INT_MIN/n * n doesn't overflow while negating one operand it does + if n is a power of two. */ + if (INTEGRAL_TYPE_P (TREE_TYPE (t)) + && ! TYPE_OVERFLOW_WRAPS (TREE_TYPE (t)) + && ! ((TREE_CODE (TREE_OPERAND (t, 0)) == INTEGER_CST + && ! integer_pow2p (TREE_OPERAND (t, 0))) + || (TREE_CODE (TREE_OPERAND (t, 1)) == INTEGER_CST + && ! integer_pow2p (TREE_OPERAND (t, 1))))) + break; /* Fall through. */ |