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| author | kazu <kazu@138bc75d-0d04-0410-961f-82ee72b054a4> | 2003-09-29 17:35:11 +0000 |
|---|---|---|
| committer | kazu <kazu@138bc75d-0d04-0410-961f-82ee72b054a4> | 2003-09-29 17:35:11 +0000 |
| commit | 79e45861c136c36ff36f734b217510c9f736f393 (patch) | |
| tree | 0f7ea83bcc8f21bb26c3a1a6dd61d42a9f950cb5 | |
| parent | 88e1c3026b07ba880d080b3739c58873f982917b (diff) | |
| download | ppe42-gcc-79e45861c136c36ff36f734b217510c9f736f393.tar.gz ppe42-gcc-79e45861c136c36ff36f734b217510c9f736f393.zip | |
* fold-const.c (fold): Fold (A & ~B) - (A & B) into
(A ^ B) - B, where B is any power of 2 minus 1.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@71910 138bc75d-0d04-0410-961f-82ee72b054a4
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/fold-const.c | 23 |
2 files changed, 28 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 96a7ad4fa65..307e9b76fd9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2003-09-29 Kazu Hirata <kazu@cs.umass.edu> + + * fold-const.c (fold): Fold (A & ~B) - (A & B) into + (A ^ B) - B, where B is any power of 2 minus 1. + Mon Sep 29 19:05:46 CEST 2003 Jan Hubicka <jh@suse.cz> * libgcov.c (gcov_exit): Fix two pastos. diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 96d46263df2..3cfa5454360 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. */ |
