diff options
| author | rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2009-03-31 14:28:16 +0000 |
|---|---|---|
| committer | rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4> | 2009-03-31 14:28:16 +0000 |
| commit | 172e662bea3dd45f48f4155bfa34df25d552d465 (patch) | |
| tree | 3375dd6b6a930ea767bbaf4394885cf7b47d7023 /gcc/fold-const.c | |
| parent | 401d1fb3672e35a37032eedfbbbdb5d5c6680b69 (diff) | |
| download | gcc-172e662bea3dd45f48f4155bfa34df25d552d465.tar.gz | |
2009-03-31 Richard Guenther <rguenther@suse.de>
PR middle-end/31029
* fold-const.c (fold_binary): Fold X +- Y CMP X to Y CMP 0 for
equality comparisons. Fold C - X CMP X if C % 2 == 1.
* gcc.dg/fold-compare-4.c: New testcase.
* gcc.dg/fold-compare-5.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@145345 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 4951600a297..ec069541412 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -12191,22 +12191,33 @@ 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) + /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */ + if ((TREE_CODE (arg0) == PLUS_EXPR + || TREE_CODE (arg0) == POINTER_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); + tree val = TREE_OPERAND (arg0, 1); + return omit_two_operands (type, + fold_build2 (code, type, + val, + build_int_cst (TREE_TYPE (val), + 0)), + TREE_OPERAND (arg0, 0), arg1); + } - 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); + /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */ + if (TREE_CODE (arg0) == MINUS_EXPR + && TREE_CODE (TREE_OPERAND (arg0, 0)) == INTEGER_CST + && operand_equal_p (TREE_OPERAND (arg0, 1), arg1, 0) + && (TREE_INT_CST_LOW (TREE_OPERAND (arg0, 0)) & 1) == 1) + { + return omit_two_operands (type, + code == NE_EXPR + ? boolean_true_node : boolean_false_node, + TREE_OPERAND (arg0, 1), arg1); } /* If we have X - Y == 0, we can convert that to X == Y and similarly |