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| author | Richard Kenner <kenner@gcc.gnu.org> | 1992-12-28 06:07:05 -0500 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1992-12-28 06:07:05 -0500 |
| commit | 85d2e16cf73d8c815b73fe2d4680512a5669a768 (patch) | |
| tree | c7e960f29f5b9c5572d29f4ef46058dce0140065 /gcc/fold-const.c | |
| parent | 4a0094c3e9d349376b2282995fd85f53c17b2962 (diff) | |
| download | gcc-85d2e16cf73d8c815b73fe2d4680512a5669a768.zip gcc-85d2e16cf73d8c815b73fe2d4680512a5669a768.tar.gz gcc-85d2e16cf73d8c815b73fe2d4680512a5669a768.tar.bz2 | |
(fold, case BIT_IOR_EXPR): Convert the IOR of a pair of shifts into a
rotate when it is equivalent.
From-SVN: r2970
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index f7c2b8a..2ff043f 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -3496,6 +3496,28 @@ fold (expr) t1 = distribute_bit_expr (code, type, arg0, arg1); if (t1 != NULL_TREE) return t1; + + /* (a << C1) | (a >> C2) if A is unsigned and C1+C2 is the size of A + is a rotate of A by C1 bits. */ + + if ((TREE_CODE (arg0) == RSHIFT_EXPR + || TREE_CODE (arg0) == LSHIFT_EXPR) + && (TREE_CODE (arg1) == RSHIFT_EXPR + || TREE_CODE (arg1) == LSHIFT_EXPR) + && TREE_CODE (arg0) != TREE_CODE (arg1) + && operand_equal_p (TREE_OPERAND (arg0, 0), TREE_OPERAND (arg1,0), 0) + && TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (arg0, 0))) + && TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST + && TREE_CODE (TREE_OPERAND (arg1, 1)) == INTEGER_CST + && TREE_INT_CST_HIGH (TREE_OPERAND (arg0, 1)) == 0 + && TREE_INT_CST_HIGH (TREE_OPERAND (arg1, 1)) == 0 + && ((TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1)) + + TREE_INT_CST_LOW (TREE_OPERAND (arg1, 1))) + == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (arg0, 0))))) + return build (LROTATE_EXPR, type, TREE_OPERAND (arg0, 0), + TREE_CODE (arg0) == LSHIFT_EXPR + ? TREE_OPERAND (arg0, 1) : TREE_OPERAND (arg1, 1)); + goto associate; case BIT_XOR_EXPR: |