ConstantRange.h revision 9850a288664087875c7c35bec8c92b72a72ac142 
1//===-- llvm/Support/ConstantRange.h - Represent a range --------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// 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 can be used to represent either signed or
28// unsigned ranges.
29//
30//===----------------------------------------------------------------------===//
31
32#ifndef LLVM_SUPPORT_CONSTANT_RANGE_H
33#define LLVM_SUPPORT_CONSTANT_RANGE_H
34
35#include "llvm/ADT/APInt.h"
36#include "llvm/System/DataTypes.h"
37
38namespace llvm {
39
40/// ConstantRange - This class represents an range of values.
41///
42class ConstantRange {
43  APInt Lower, Upper;
44  static ConstantRange intersect1Wrapped(const ConstantRange &LHS,
45                                         const ConstantRange &RHS);
46
47public:
48  /// Initialize a full (the default) or empty set for the specified bit width.
49  ///
50  explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
51
52  /// Initialize a range to hold the single specified value.
53  ///
54  ConstantRange(const APInt &Value);
55
56  /// @brief Initialize a range of values explicitly. This will assert out if
57  /// Lower==Upper and Lower != Min or Max value for its type. It will also
58  /// assert out if the two APInt's are not the same bit width.
59  ConstantRange(const APInt& Lower, const APInt& Upper);
60
61  /// makeICmpRegion - Produce the smallest range that contains all values that
62  /// might satisfy the comparison specified by Pred when compared to any value
63  /// contained within Other.
64  ///
65  /// Solves for range X in 'for all x in X, there exists a y in Y such that
66  /// icmp op x, y is true'. Every value that might make the comparison true
67  /// is included in the resulting range.
68  static ConstantRange makeICmpRegion(unsigned Pred,
69                                      const ConstantRange &Other);
70
71  /// getLower - Return the lower value for this range...
72  ///
73  const APInt &getLower() const { return Lower; }
74
75  /// getUpper - Return the upper value for this range...
76  ///
77  const APInt &getUpper() const { return Upper; }
78
79  /// getBitWidth - get the bit width of this ConstantRange
80  ///
81  uint32_t getBitWidth() const { return Lower.getBitWidth(); }
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() const;
96
97  /// contains - Return true if the specified value is in the set.
98  ///
99  bool contains(const APInt &Val) const;
100
101  /// contains - Return true if the other range is a subset of this one.
102  ///
103  bool contains(const ConstantRange &CR) const;
104
105  /// getSingleElement - If this set contains a single element, return it,
106  /// otherwise return null.
107  ///
108  const APInt *getSingleElement() const {
109    if (Upper == Lower + 1)
110      return &Lower;
111    return 0;
112  }
113
114  /// isSingleElement - Return true if this set contains exactly one member.
115  ///
116  bool isSingleElement() const { return getSingleElement() != 0; }
117
118  /// getSetSize - Return the number of elements in this set.
119  ///
120  APInt getSetSize() const;
121
122  /// getUnsignedMax - Return the largest unsigned value contained in the
123  /// ConstantRange.
124  ///
125  APInt getUnsignedMax() const;
126
127  /// getUnsignedMin - Return the smallest unsigned value contained in the
128  /// ConstantRange.
129  ///
130  APInt getUnsignedMin() const;
131
132  /// getSignedMax - Return the largest signed value contained in the
133  /// ConstantRange.
134  ///
135  APInt getSignedMax() const;
136
137  /// getSignedMin - Return the smallest signed value contained in the
138  /// ConstantRange.
139  ///
140  APInt getSignedMin() const;
141
142  /// operator= - Copy one ConstantRange over another.
143  void operator=(const ConstantRange &CR) {
144    Lower = CR.Lower;
145    Upper = CR.Upper;
146  }
147
148  /// operator== - Return true if this range is equal to another range.
149  ///
150  bool operator==(const ConstantRange &CR) const {
151    return Lower == CR.Lower && Upper == CR.Upper;
152  }
153  bool operator!=(const ConstantRange &CR) const {
154    return !operator==(CR);
155  }
156
157  /// subtract - Subtract the specified constant from the endpoints of this
158  /// constant range.
159  ConstantRange subtract(const APInt &CI) const;
160
161  /// intersectWith - Return the range that results from the intersection of
162  /// this range with another range.  The resultant range is guaranteed to
163  /// include all elements contained in both input ranges, and to have the
164  /// smallest possible set size that does so.  Because there may be two
165  /// intersections with the same set size, A.intersectWith(B) might not
166  /// be equal to B.intersectWith(A).
167  ///
168  ConstantRange intersectWith(const ConstantRange &CR) const;
169
170  /// unionWith - Return the range that results from the union of this range
171  /// with another range.  The resultant range is guaranteed to include the
172  /// elements of both sets, but may contain more.  For example, [3, 9) union
173  /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
174  /// in either set before.
175  ///
176  ConstantRange unionWith(const ConstantRange &CR) const;
177
178  /// zeroExtend - Return a new range in the specified integer type, which must
179  /// be strictly larger than the current type.  The returned range will
180  /// correspond to the possible range of values if the source range had been
181  /// zero extended to BitWidth.
182  ConstantRange zeroExtend(uint32_t BitWidth) const;
183
184  /// signExtend - Return a new range in the specified integer type, which must
185  /// be strictly larger than the current type.  The returned range will
186  /// correspond to the possible range of values if the source range had been
187  /// sign extended to BitWidth.
188  ConstantRange signExtend(uint32_t BitWidth) const;
189
190  /// truncate - Return a new range in the specified integer type, which must be
191  /// strictly smaller than the current type.  The returned range will
192  /// correspond to the possible range of values if the source range had been
193  /// truncated to the specified type.
194  ConstantRange truncate(uint32_t BitWidth) const;
195
196  /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
197  /// value is zero extended, truncated, or left alone to make it that width.
198  ConstantRange zextOrTrunc(uint32_t BitWidth) const;
199
200  /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
201  /// value is sign extended, truncated, or left alone to make it that width.
202  ConstantRange sextOrTrunc(uint32_t BitWidth) const;
203
204  /// add - Return a new range representing the possible values resulting
205  /// from an addition of a value in this range and a value in Other.
206  ConstantRange add(const ConstantRange &Other) const;
207
208  /// multiply - Return a new range representing the possible values resulting
209  /// from a multiplication of a value in this range and a value in Other.
210  /// TODO: This isn't fully implemented yet.
211  ConstantRange multiply(const ConstantRange &Other) const;
212
213  /// smax - Return a new range representing the possible values resulting
214  /// from a signed maximum of a value in this range and a value in Other.
215  ConstantRange smax(const ConstantRange &Other) const;
216
217  /// umax - Return a new range representing the possible values resulting
218  /// from an unsigned maximum of a value in this range and a value in Other.
219  ConstantRange umax(const ConstantRange &Other) const;
220
221  /// udiv - Return a new range representing the possible values resulting
222  /// from an unsigned division of a value in this range and a value in Other.
223  /// TODO: This isn't fully implemented yet.
224  ConstantRange udiv(const ConstantRange &Other) const;
225
226  /// shl - Return a new range representing the possible values resulting
227  /// from a left shift of a value in this range by the Amount value.
228  ConstantRange shl(const ConstantRange &Amount) const;
229
230  /// ashr - Return a new range representing the possible values resulting from
231  /// an arithmetic right shift of a value in this range by the Amount value.
232  ConstantRange ashr(const ConstantRange &Amount) const;
233
234  /// shr - Return a new range representing the possible values resulting
235  /// from a logical right shift of a value in this range by the Amount value.
236  ConstantRange lshr(const ConstantRange &Amount) const;
237
238  /// print - Print out the bounds to a stream...
239  ///
240  void print(raw_ostream &OS) const;
241
242  /// dump - Allow printing from a debugger easily...
243  ///
244  void dump() const;
245};
246
247inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
248  CR.print(OS);
249  return OS;
250}
251
252} // End llvm namespace
253
254#endif
255