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/Support/DataTypes.h"
37
38namespace llvm {
39
40/// ConstantRange - This class represents an range of values.
41///
42class ConstantRange {
43  APInt Lower, Upper;
44
45public:
46  /// Initialize a full (the default) or empty set for the specified bit width.
47  ///
48  explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
49
50  /// Initialize a range to hold the single specified value.
51  ///
52  ConstantRange(const APInt &Value);
53
54  /// @brief Initialize a range of values explicitly. This will assert out if
55  /// Lower==Upper and Lower != Min or Max value for its type. It will also
56  /// assert out if the two APInt's are not the same bit width.
57  ConstantRange(const APInt &Lower, const APInt &Upper);
58
59  /// makeICmpRegion - Produce the smallest range that contains all values that
60  /// might satisfy the comparison specified by Pred when compared to any value
61  /// contained within Other.
62  ///
63  /// Solves for range X in 'for all x in X, there exists a y in Y such that
64  /// icmp op x, y is true'. Every value that might make the comparison true
65  /// is included in the resulting range.
66  static ConstantRange makeICmpRegion(unsigned Pred,
67                                      const ConstantRange &Other);
68
69  /// getLower - Return the lower value for this range...
70  ///
71  const APInt &getLower() const { return Lower; }
72
73  /// getUpper - Return the upper value for this range...
74  ///
75  const APInt &getUpper() const { return Upper; }
76
77  /// getBitWidth - get the bit width of this ConstantRange
78  ///
79  uint32_t getBitWidth() const { return Lower.getBitWidth(); }
80
81  /// isFullSet - Return true if this set contains all of the elements possible
82  /// for this data-type
83  ///
84  bool isFullSet() const;
85
86  /// isEmptySet - Return true if this set contains no members.
87  ///
88  bool isEmptySet() const;
89
90  /// isWrappedSet - Return true if this set wraps around the top of the range,
91  /// for example: [100, 8)
92  ///
93  bool isWrappedSet() const;
94
95  /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
96  /// its bitwidth, for example: i8 [120, 140).
97  ///
98  bool isSignWrappedSet() const;
99
100  /// contains - Return true if the specified value is in the set.
101  ///
102  bool contains(const APInt &Val) const;
103
104  /// contains - Return true if the other range is a subset of this one.
105  ///
106  bool contains(const ConstantRange &CR) const;
107
108  /// getSingleElement - If this set contains a single element, return it,
109  /// otherwise return null.
110  ///
111  const APInt *getSingleElement() const {
112    if (Upper == Lower + 1)
113      return &Lower;
114    return 0;
115  }
116
117  /// isSingleElement - Return true if this set contains exactly one member.
118  ///
119  bool isSingleElement() const { return getSingleElement() != 0; }
120
121  /// getSetSize - Return the number of elements in this set.
122  ///
123  APInt getSetSize() const;
124
125  /// getUnsignedMax - Return the largest unsigned value contained in the
126  /// ConstantRange.
127  ///
128  APInt getUnsignedMax() const;
129
130  /// getUnsignedMin - Return the smallest unsigned value contained in the
131  /// ConstantRange.
132  ///
133  APInt getUnsignedMin() const;
134
135  /// getSignedMax - Return the largest signed value contained in the
136  /// ConstantRange.
137  ///
138  APInt getSignedMax() const;
139
140  /// getSignedMin - Return the smallest signed value contained in the
141  /// ConstantRange.
142  ///
143  APInt getSignedMin() const;
144
145  /// operator== - Return true if this range is equal to another range.
146  ///
147  bool operator==(const ConstantRange &CR) const {
148    return Lower == CR.Lower && Upper == CR.Upper;
149  }
150  bool operator!=(const ConstantRange &CR) const {
151    return !operator==(CR);
152  }
153
154  /// subtract - Subtract the specified constant from the endpoints of this
155  /// constant range.
156  ConstantRange subtract(const APInt &CI) const;
157
158  /// \brief Subtract the specified range from this range (aka relative
159  /// complement of the sets).
160  ConstantRange difference(const ConstantRange &CR) const;
161
162  /// intersectWith - Return the range that results from the intersection of
163  /// this range with another range.  The resultant range is guaranteed to
164  /// include all elements contained in both input ranges, and to have the
165  /// smallest possible set size that does so.  Because there may be two
166  /// intersections with the same set size, A.intersectWith(B) might not
167  /// be equal to B.intersectWith(A).
168  ///
169  ConstantRange intersectWith(const ConstantRange &CR) const;
170
171  /// unionWith - Return the range that results from the union of this range
172  /// with another range.  The resultant range is guaranteed to include the
173  /// elements of both sets, but may contain more.  For example, [3, 9) union
174  /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
175  /// in either set before.
176  ///
177  ConstantRange unionWith(const ConstantRange &CR) const;
178
179  /// zeroExtend - Return a new range in the specified integer type, which must
180  /// be strictly larger than the current type.  The returned range will
181  /// correspond to the possible range of values if the source range had been
182  /// zero extended to BitWidth.
183  ConstantRange zeroExtend(uint32_t BitWidth) const;
184
185  /// signExtend - Return a new range in the specified integer type, which must
186  /// be strictly larger than the current type.  The returned range will
187  /// correspond to the possible range of values if the source range had been
188  /// sign extended to BitWidth.
189  ConstantRange signExtend(uint32_t BitWidth) const;
190
191  /// truncate - Return a new range in the specified integer type, which must be
192  /// strictly smaller than the current type.  The returned range will
193  /// correspond to the possible range of values if the source range had been
194  /// truncated to the specified type.
195  ConstantRange truncate(uint32_t BitWidth) const;
196
197  /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
198  /// value is zero extended, truncated, or left alone to make it that width.
199  ConstantRange zextOrTrunc(uint32_t BitWidth) const;
200
201  /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
202  /// value is sign extended, truncated, or left alone to make it that width.
203  ConstantRange sextOrTrunc(uint32_t BitWidth) const;
204
205  /// add - Return a new range representing the possible values resulting
206  /// from an addition of a value in this range and a value in \p Other.
207  ConstantRange add(const ConstantRange &Other) const;
208
209  /// sub - Return a new range representing the possible values resulting
210  /// from a subtraction of a value in this range and a value in \p Other.
211  ConstantRange sub(const ConstantRange &Other) const;
212
213  /// multiply - Return a new range representing the possible values resulting
214  /// from a multiplication of a value in this range and a value in \p Other.
215  /// TODO: This isn't fully implemented yet.
216  ConstantRange multiply(const ConstantRange &Other) const;
217
218  /// smax - Return a new range representing the possible values resulting
219  /// from a signed maximum of a value in this range and a value in \p Other.
220  ConstantRange smax(const ConstantRange &Other) const;
221
222  /// umax - Return a new range representing the possible values resulting
223  /// from an unsigned maximum of a value in this range and a value in \p Other.
224  ConstantRange umax(const ConstantRange &Other) const;
225
226  /// udiv - Return a new range representing the possible values resulting
227  /// from an unsigned division of a value in this range and a value in
228  /// \p Other.
229  ConstantRange udiv(const ConstantRange &Other) const;
230
231  /// binaryAnd - return a new range representing the possible values resulting
232  /// from a binary-and of a value in this range by a value in \p Other.
233  ConstantRange binaryAnd(const ConstantRange &Other) const;
234
235  /// binaryOr - return a new range representing the possible values resulting
236  /// from a binary-or of a value in this range by a value in \p Other.
237  ConstantRange binaryOr(const ConstantRange &Other) const;
238
239  /// shl - Return a new range representing the possible values resulting
240  /// from a left shift of a value in this range by a value in \p Other.
241  /// TODO: This isn't fully implemented yet.
242  ConstantRange shl(const ConstantRange &Other) const;
243
244  /// lshr - Return a new range representing the possible values resulting
245  /// from a logical right shift of a value in this range and a value in
246  /// \p Other.
247  ConstantRange lshr(const ConstantRange &Other) const;
248
249  /// inverse - Return a new range that is the logical not of the current set.
250  ///
251  ConstantRange inverse() const;
252
253  /// print - Print out the bounds to a stream...
254  ///
255  void print(raw_ostream &OS) const;
256
257  /// dump - Allow printing from a debugger easily...
258  ///
259  void dump() const;
260};
261
262inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
263  CR.print(OS);
264  return OS;
265}
266
267} // End llvm namespace
268
269#endif
270