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| author | Richard Guenther <rguenther@suse.de> | 2007-02-24 19:55:47 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2007-02-24 19:55:47 +0000 |
| commit | a31498d293913e1006bd43e67884983a02471d1a (patch) | |
| tree | 519e3bd036acaa7e2d9abb7b298d90d27eb168d5 /gcc/fold-const.c | |
| parent | 1e6e2c303b65dc3aab3a3bd8e63416a585de88b2 (diff) | |
| download | gcc-a31498d293913e1006bd43e67884983a02471d1a.zip gcc-a31498d293913e1006bd43e67884983a02471d1a.tar.gz gcc-a31498d293913e1006bd43e67884983a02471d1a.tar.bz2 | |
re PR middle-end/30951 (Does not fold x + CST == x and x + CST != x)
2007-02-24 Richard Guenther <rguenther@suse.de>
PR middle-end/30951
* fold-const.c (fold_binary): Fold x +- CST op x for
EQ_EXPR and NE_EXPR.
* gcc.dg/pr30951.c: New testcase.
From-SVN: r122295
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 |