diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index ffd63cf..80c3c41 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -11203,6 +11203,24 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) fold_convert (TREE_TYPE (arg0), arg1), TREE_OPERAND (arg0, 1))); + /* Transform comparisons of the form X +- C CMP X. */ + if ((TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR) + && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0) + && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST + && (INTEGRAL_TYPE_P (TREE_TYPE (arg0)) + || POINTER_TYPE_P (TREE_TYPE (arg0)))) + { + tree cst = TREE_OPERAND (arg0, 1); + + if (code == EQ_EXPR + && !integer_zerop (cst)) + return omit_two_operands (type, boolean_false_node, + TREE_OPERAND (arg0, 0), arg1); + else + return omit_two_operands (type, boolean_true_node, + TREE_OPERAND (arg0, 0), arg1); + } + /* If we have X - Y == 0, we can convert that to X == Y and similarly for !=. Don't do this for ordered comparisons due to overflow. */ if (TREE_CODE (arg0) == MINUS_EXPR |