+2005-06-12 James A. Morrison <phython@gcc.gnu.org>
+
+ PR tree-optimization/14796
+ * fold-const (fold_binary): Transform (X << C) >> C into X & (-1>>C)
+ for unsigned types.
+
2005-06-12 Kazu Hirata <kazu@codesourcery.com>
* cgraphunit.c, tree-ssa-loop-ivopts.c,
build_int_cst (type, low));
}
- /* Transform (x >> c) << c into x & (-1<<c) */
- if (code == LSHIFT_EXPR && TREE_CODE (arg0) == RSHIFT_EXPR
+ /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
+ into x & ((unsigned)-1 >> c) for unsigned types. */
+ if (((code == LSHIFT_EXPR && TREE_CODE (arg0) == RSHIFT_EXPR)
+ || (TYPE_UNSIGNED (type)
+ && code == RSHIFT_EXPR && TREE_CODE (arg0) == LSHIFT_EXPR))
&& host_integerp (arg1, false)
&& TREE_INT_CST_LOW (arg1) < TYPE_PRECISION (type)
&& host_integerp (TREE_OPERAND (arg0, 1), false)
{
HOST_WIDE_INT low0 = TREE_INT_CST_LOW (TREE_OPERAND (arg0, 1));
HOST_WIDE_INT low1 = TREE_INT_CST_LOW (arg1);
- unsigned HOST_WIDE_INT low;
- HOST_WIDE_INT high;
tree lshift;
tree arg00;
{
arg00 = fold_convert (type, TREE_OPERAND (arg0, 0));
- lshift_double (-1, -1, low0 < low1 ? low0 : low1,
- TYPE_PRECISION (type), &low, &high, 1);
- lshift = build_int_cst_wide (type, low, high);
+ lshift = build_int_cst (type, -1);
+ lshift = int_const_binop (code, lshift, arg1, 0);
return fold_build2 (BIT_AND_EXPR, type, arg00, lshift);
}
}
-
/* Rewrite an LROTATE_EXPR by a constant into an
RROTATE_EXPR by a new constant. */
if (code == LROTATE_EXPR && TREE_CODE (arg1) == INTEGER_CST)
return (b >> 5) << 5;
}
+unsigned long long h (unsigned long long c) {
+ return (c << 60) >> 60;
+}
+
+int l (int d) {
+ return (d << 6) >> 6;
+}
+
/* { dg-final { scan-tree-dump "a << 9" "gimple" } } */
/* { dg-final { scan-tree-dump "b & -32" "gimple" } } */
+/* { dg-final { scan-tree-dump "c & 15" "gimple" } } */
+/* { dg-final { scan-tree-dump "d << 6" "gimple" } } */
/* { dg-final { cleanup-tree-dump "gimple" } } */