1/* Header file for range operator class.
2   Copyright (C) 2017-2020 Free Software Foundation, Inc.
3   Contributed by Andrew MacLeod <amacleod@redhat.com>
4   and Aldy Hernandez <aldyh@redhat.com>.
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify it under
9the terms of the GNU General Public License as published by the Free
10Software Foundation; either version 3, or (at your option) any later
11version.
12
13GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14WARRANTY; without even the implied warranty of MERCHANTABILITY or
15FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
16 for more details.
17
18You should have received a copy of the GNU General Public License
19along with GCC; see the file COPYING3.  If not see
20<http://www.gnu.org/licenses/>.  */
21
22#ifndef GCC_RANGE_OP_H
23#define GCC_RANGE_OP_H
24
25// This class is implemented for each kind of operator supported by
26// the range generator.  It serves various purposes.
27//
28// 1 - Generates range information for the specific operation between
29//     two ranges.  This provides the ability to fold ranges for an
30//     expression.
31//
32// 2 - Performs range algebra on the expression such that a range can be
33//     adjusted in terms of one of the operands:
34//
35//       def = op1 + op2
36//
37//     Given a range for def, we can adjust the range so that it is in
38//     terms of either operand.
39//
40//     op1_range (def_range, op2) will adjust the range in place so it
41//     is in terms of op1.  Since op1 = def - op2, it will subtract
42//     op2 from each element of the range.
43//
44// 3 - Creates a range for an operand based on whether the result is 0 or
45//     non-zero.  This is mostly for logical true false, but can serve other
46//     purposes.
47//       ie   0 = op1 - op2 implies op2 has the same range as op1.
48
49class range_operator
50{
51public:
52  // Perform an operation between 2 ranges and return it.
53  virtual bool fold_range (value_range &r, tree type,
54			   const value_range &lh,
55			   const value_range &rh) const;
56
57  // Return the range for op[12] in the general case.  LHS is the range for
58  // the LHS of the expression, OP[12]is the range for the other
59  //
60  // The operand and the result is returned in R.
61  //
62  // TYPE is the expected type of the range.
63  //
64  // Return TRUE if the operation is performed and a valid range is available.
65  //
66  // i.e.  [LHS] = ??? + OP2
67  // is re-formed as R = [LHS] - OP2.
68  virtual bool op1_range (value_range &r, tree type,
69			  const value_range &lhs,
70			  const value_range &op2) const;
71  virtual bool op2_range (value_range &r, tree type,
72			  const value_range &lhs,
73			  const value_range &op1) const;
74
75protected:
76  // Perform an integral operation between 2 sub-ranges and return it.
77  virtual void wi_fold (value_range &r, tree type,
78		        const wide_int &lh_lb,
79		        const wide_int &lh_ub,
80		        const wide_int &rh_lb,
81		        const wide_int &rh_ub) const;
82};
83
84extern range_operator *range_op_handler (enum tree_code code, tree type);
85extern void range_cast (value_range &, tree type);
86extern void wi_set_zero_nonzero_bits (tree type,
87				      const wide_int &, const wide_int &,
88				      wide_int &maybe_nonzero,
89				      wide_int &mustbe_nonzero);
90
91#endif // GCC_RANGE_OP_H
92