diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index f1927f2..bc1e877 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -6589,6 +6589,17 @@ fold (tree expr) if (fold_real_zero_addition_p (TREE_TYPE (arg1), arg0, 0)) return non_lvalue (fold_convert (type, arg1)); + /* Convert X + -C into X - C. */ + if (TREE_CODE (arg1) == REAL_CST + && REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1))) + { + tem = fold_negate_const (arg1, type); + if (!TREE_OVERFLOW (arg1) || !flag_trapping_math) + return fold (build2 (MINUS_EXPR, type, + fold_convert (type, arg0), + fold_convert (type, tem))); + } + /* Convert x+x into x*2.0. */ if (operand_equal_p (arg0, arg1, 0) && SCALAR_FLOAT_TYPE_P (type)) @@ -6921,7 +6932,10 @@ fold (tree expr) /* A - B -> A + (-B) if B is easily negatable. */ if (!wins && negate_expr_p (arg1) - && (FLOAT_TYPE_P (type) + && ((FLOAT_TYPE_P (type) + /* Avoid this transformation if B is a positive REAL_CST. */ + && (TREE_CODE (arg1) != REAL_CST + || REAL_VALUE_NEGATIVE (TREE_REAL_CST (arg1)))) || (INTEGRAL_TYPE_P (type) && flag_wrapv && !flag_trapv))) return fold (build2 (PLUS_EXPR, type, arg0, negate_expr (arg1))); |