ConstantRange.h revision 663e711dc235cae94eb50abb1c0571fd0b3a6a35 
1//===-- llvm/Support/ConstantRange.h - Represent a range --------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Represent a range of possible values that may occur when the program is run
11// for an integral value.  This keeps track of a lower and upper bound for the
12// constant, which MAY wrap around the end of the numeric range.  To do this, it
13// keeps track of a [lower, upper) bound, which specifies an interval just like
14// STL iterators.  When used with boolean values, the following are important
15// ranges: :
16//
17//  [F, F) = {}     = Empty set
18//  [T, F) = {T}
19//  [F, T) = {F}
20//  [T, T) = {F, T} = Full set
21//
22// The other integral ranges use min/max values for special range values. For
23// example, for 8-bit types, it uses:
24// [0, 0)     = {}       = Empty set
25// [255, 255) = {0..255} = Full Set
26//
27// Note that ConstantRange always keeps unsigned values.
28//===----------------------------------------------------------------------===//
29
30#ifndef LLVM_SUPPORT_CONSTANT_RANGE_H
31#define LLVM_SUPPORT_CONSTANT_RANGE_H
32
33#include "llvm/ADT/APInt.h"
34#include "llvm/Support/DataTypes.h"
35#include "llvm/Support/Streams.h"
36#include <iosfwd>
37
38namespace llvm {
39class Constant;
40class ConstantInt;
41class Type;
42
43class ConstantRange {
44  APInt Lower, Upper;
45  static ConstantRange intersect1Wrapped(const ConstantRange &LHS,
46                                         const ConstantRange &RHS, bool sign);
47 public:
48  /// Initialize a full (the default) or empty set for the specified type.
49  ///
50  ConstantRange(const Type *Ty, bool isFullSet = true);
51
52  /// Initialize a range to hold the single specified value.
53  ///
54  ConstantRange(Constant *Value);
55
56  /// Initialize a range of values explicitly... this will assert out if
57  /// Lower==Upper and Lower != Min or Max for its type, if the two constants
58  /// have different types, or if the constant are not integral values.
59  ///
60  ConstantRange(Constant *Lower, Constant *Upper);
61
62  /// @brief Initialize a range of values explicitly.
63  ConstantRange(const APInt& Lower, const APInt& Upper);
64
65  /// Initialize a set of values that all satisfy the predicate with C. The
66  /// predicate should be either an ICmpInst::Predicate or FCmpInst::Predicate
67  /// value.
68  /// @brief Get a range for a relation with a constant integral.
69  ConstantRange(unsigned short predicate, ConstantInt *C);
70
71  /// getLower - Return the lower value for this range...
72  ///
73  ConstantInt *getLower() const;
74
75  /// getUpper - Return the upper value for this range...
76  ///
77  ConstantInt *getUpper() const;
78
79  /// getType - Return the LLVM data type of this range.
80  ///
81  const Type *getType() const;
82
83  /// isFullSet - Return true if this set contains all of the elements possible
84  /// for this data-type
85  ///
86  bool isFullSet() const;
87
88  /// isEmptySet - Return true if this set contains no members.
89  ///
90  bool isEmptySet() const;
91
92  /// isWrappedSet - Return true if this set wraps around the top of the range,
93  /// for example: [100, 8)
94  ///
95  bool isWrappedSet(bool isSigned) const;
96
97  /// contains - Return true if the specified value is in the set.
98  /// The isSigned parameter indicates whether the comparisons should be
99  /// performed as if the values are signed or not.
100  ///
101  bool contains(ConstantInt *Val, bool isSigned) const;
102
103  /// getSingleElement - If this set contains a single element, return it,
104  /// otherwise return null.
105  ///
106  ConstantInt *getSingleElement() const;
107
108  /// isSingleElement - Return true if this set contains exactly one member.
109  ///
110  bool isSingleElement() const { return getSingleElement() != 0; }
111
112  /// getSetSize - Return the number of elements in this set.
113  ///
114  APInt getSetSize() const;
115
116  /// operator== - Return true if this range is equal to another range.
117  ///
118  bool operator==(const ConstantRange &CR) const {
119    return Lower == CR.Lower && Upper == CR.Upper;
120  }
121  bool operator!=(const ConstantRange &CR) const {
122    return !operator==(CR);
123  }
124
125  /// subtract - Subtract the specified constant from the endpoints of this
126  /// constant range.
127  ConstantRange subtract(ConstantInt *CI) const;
128
129  /// intersectWith - Return the range that results from the intersection of
130  /// this range with another range.  The resultant range is pruned as much as
131  /// possible, but there may be cases where elements are included that are in
132  /// one of the sets but not the other.  For example: [100, 8) intersect [3,
133  /// 120) yields [3, 120)
134  ///
135  ConstantRange intersectWith(const ConstantRange &CR, bool isSigned) const;
136
137  /// unionWith - Return the range that results from the union of this range
138  /// with another range.  The resultant range is guaranteed to include the
139  /// elements of both sets, but may contain more.  For example, [3, 9) union
140  /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
141  /// in either set before.
142  ///
143  ConstantRange unionWith(const ConstantRange &CR, bool isSigned) const;
144
145  /// zeroExtend - Return a new range in the specified integer type, which must
146  /// be strictly larger than the current type.  The returned range will
147  /// correspond to the possible range of values if the source range had been
148  /// zero extended.
149  ConstantRange zeroExtend(const Type *Ty) const;
150
151  /// truncate - Return a new range in the specified integer type, which must be
152  /// strictly smaller than the current type.  The returned range will
153  /// correspond to the possible range of values if the source range had been
154  /// truncated to the specified type.
155  ConstantRange truncate(const Type *Ty) const;
156
157  /// print - Print out the bounds to a stream...
158  ///
159  void print(std::ostream &OS) const;
160  void print(std::ostream *OS) const { if (OS) print(*OS); }
161
162  /// dump - Allow printing from a debugger easily...
163  ///
164  void dump() const;
165};
166
167inline std::ostream &operator<<(std::ostream &OS, const ConstantRange &CR) {
168  CR.print(OS);
169  return OS;
170}
171
172} // End llvm namespace
173
174#endif
175