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| author | Richard Kenner <kenner@gcc.gnu.org> | 1994-04-08 18:18:08 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1994-04-08 18:18:08 -0400 |
| commit | e92d30482ecfa8b870e09648544af9ad54e60ccd (patch) | |
| tree | 1a8b7d3e467624056daa3e30865e7e8bd6380057 | |
| parent | 69887ad921a264512d90b5087087476d2deead17 (diff) | |
| download | gcc-e92d30482ecfa8b870e09648544af9ad54e60ccd.zip gcc-e92d30482ecfa8b870e09648544af9ad54e60ccd.tar.gz gcc-e92d30482ecfa8b870e09648544af9ad54e60ccd.tar.bz2 | |
(fold, case GT_EXPR): Simplify X < (1 << Y) into X >> Y == 0.
From-SVN: r6999
| -rw-r--r-- | gcc/fold-const.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index e681278..4cfd2a9 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -4517,6 +4517,30 @@ fold (expr) return build (code == EQ_EXPR ? NE_EXPR : EQ_EXPR, type, arg0, integer_zero_node); + /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0 + and similarly for <= into !=. */ + if ((code == LT_EXPR || code == GE_EXPR) + && TREE_UNSIGNED (TREE_TYPE (arg0)) + && TREE_CODE (arg1) == LSHIFT_EXPR + && integer_onep (TREE_OPERAND (arg1, 0))) + return build (code == LT_EXPR ? EQ_EXPR : NE_EXPR, type, + build (RSHIFT_EXPR, TREE_TYPE (arg0), arg0, + TREE_OPERAND (arg1, 1)), + convert (TREE_TYPE (arg0), integer_zero_node)); + + else if ((code == LT_EXPR || code == GE_EXPR) + && TREE_UNSIGNED (TREE_TYPE (arg0)) + && (TREE_CODE (arg1) == NOP_EXPR + || TREE_CODE (arg1) == CONVERT_EXPR) + && TREE_CODE (TREE_OPERAND (arg1, 0)) == LSHIFT_EXPR + && integer_onep (TREE_OPERAND (TREE_OPERAND (arg1, 0), 0))) + return + build (code == LT_EXPR ? EQ_EXPR : NE_EXPR, type, + convert (TREE_TYPE (arg0), + build (RSHIFT_EXPR, TREE_TYPE (arg0), arg0, + TREE_OPERAND (TREE_OPERAND (arg1, 0), 1))), + convert (TREE_TYPE (arg0), integer_zero_node)); + /* Simplify comparison of something with itself. (For IEEE floating-point, we can only do some of these simplifications.) */ if (operand_equal_p (arg0, arg1, 0)) |