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| author | Kazu Hirata <kazu@cs.umass.edu> | 2003-09-29 17:35:11 +0000 |
|---|---|---|
| committer | Kazu Hirata <kazu@gcc.gnu.org> | 2003-09-29 17:35:11 +0000 |
| commit | 38b35623d39f02a596440e8c3845f9aa56b33893 (patch) | |
| tree | 0f7ea83bcc8f21bb26c3a1a6dd61d42a9f950cb5 /gcc/fold-const.c | |
| parent | 1ffcc3520601ae337f0c9419fb3b694ce5c4469f (diff) | |
| download | gcc-38b35623d39f02a596440e8c3845f9aa56b33893.zip gcc-38b35623d39f02a596440e8c3845f9aa56b33893.tar.gz gcc-38b35623d39f02a596440e8c3845f9aa56b33893.tar.bz2 | |
fold-const.c (fold): Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is any power of 2 minus 1.
* fold-const.c (fold): Fold (A & ~B) - (A & B) into
(A ^ B) - B, where B is any power of 2 minus 1.
From-SVN: r71910
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 96d4626..3cfa545 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -6017,6 +6017,29 @@ fold (tree expr) TREE_OPERAND (arg1, 1))), arg0)); } + + /* Fold (A & ~B) - (A & B) into (A ^ B) - B, , where B is + any power of 2 minus 1. */ + if (TREE_CODE (arg0) == BIT_AND_EXPR + && TREE_CODE (arg1) == BIT_AND_EXPR + && operand_equal_p (TREE_OPERAND (arg0, 0), + TREE_OPERAND (arg1, 0), 0) + && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST + && TREE_CODE (TREE_OPERAND (arg1, 1)) == INTEGER_CST) + { + tree mask0 = TREE_OPERAND (arg0, 1); + tree mask1 = TREE_OPERAND (arg1, 1); + tree tem = fold (build1 (BIT_NOT_EXPR, type, mask0)); + + if (operand_equal_p (tem, mask1, 0) + && integer_pow2p (fold (build (PLUS_EXPR, type, + mask1, integer_one_node)))) + { + tem = fold (build (BIT_XOR_EXPR, type, + TREE_OPERAND (arg0, 0), mask1)); + return fold (build (MINUS_EXPR, type, tem, mask1)); + } + } } /* See if ARG1 is zero and X - ARG1 reduces to X. */ |