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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 
38 namespace llvm {
39 
40 /// ConstantRange - This class represents an range of values.
41 ///
42 class ConstantRange {
43   APInt Lower, Upper;
44 
45 public:
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   ///
getLower()71   const APInt &getLower() const { return Lower; }
72 
73   /// getUpper - Return the upper value for this range...
74   ///
getUpper()75   const APInt &getUpper() const { return Upper; }
76 
77   /// getBitWidth - get the bit width of this ConstantRange
78   ///
getBitWidth()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   ///
getSingleElement()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   ///
isSingleElement()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   /// intersectWith - Return the range that results from the intersection of
159   /// this range with another range.  The resultant range is guaranteed to
160   /// include all elements contained in both input ranges, and to have the
161   /// smallest possible set size that does so.  Because there may be two
162   /// intersections with the same set size, A.intersectWith(B) might not
163   /// be equal to B.intersectWith(A).
164   ///
165   ConstantRange intersectWith(const ConstantRange &CR) const;
166 
167   /// unionWith - Return the range that results from the union of this range
168   /// with another range.  The resultant range is guaranteed to include the
169   /// elements of both sets, but may contain more.  For example, [3, 9) union
170   /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
171   /// in either set before.
172   ///
173   ConstantRange unionWith(const ConstantRange &CR) const;
174 
175   /// zeroExtend - Return a new range in the specified integer type, which must
176   /// be strictly larger than the current type.  The returned range will
177   /// correspond to the possible range of values if the source range had been
178   /// zero extended to BitWidth.
179   ConstantRange zeroExtend(uint32_t BitWidth) const;
180 
181   /// signExtend - Return a new range in the specified integer type, which must
182   /// be strictly larger than the current type.  The returned range will
183   /// correspond to the possible range of values if the source range had been
184   /// sign extended to BitWidth.
185   ConstantRange signExtend(uint32_t BitWidth) const;
186 
187   /// truncate - Return a new range in the specified integer type, which must be
188   /// strictly smaller than the current type.  The returned range will
189   /// correspond to the possible range of values if the source range had been
190   /// truncated to the specified type.
191   ConstantRange truncate(uint32_t BitWidth) const;
192 
193   /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
194   /// value is zero extended, truncated, or left alone to make it that width.
195   ConstantRange zextOrTrunc(uint32_t BitWidth) const;
196 
197   /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
198   /// value is sign extended, truncated, or left alone to make it that width.
199   ConstantRange sextOrTrunc(uint32_t BitWidth) const;
200 
201   /// add - Return a new range representing the possible values resulting
202   /// from an addition of a value in this range and a value in \p Other.
203   ConstantRange add(const ConstantRange &Other) const;
204 
205   /// sub - Return a new range representing the possible values resulting
206   /// from a subtraction of a value in this range and a value in \p Other.
207   ConstantRange sub(const ConstantRange &Other) const;
208 
209   /// multiply - Return a new range representing the possible values resulting
210   /// from a multiplication of a value in this range and a value in \p Other.
211   /// TODO: This isn't fully implemented yet.
212   ConstantRange multiply(const ConstantRange &Other) const;
213 
214   /// smax - Return a new range representing the possible values resulting
215   /// from a signed maximum of a value in this range and a value in \p Other.
216   ConstantRange smax(const ConstantRange &Other) const;
217 
218   /// umax - Return a new range representing the possible values resulting
219   /// from an unsigned maximum of a value in this range and a value in \p Other.
220   ConstantRange umax(const ConstantRange &Other) const;
221 
222   /// udiv - Return a new range representing the possible values resulting
223   /// from an unsigned division of a value in this range and a value in
224   /// \p Other.
225   ConstantRange udiv(const ConstantRange &Other) const;
226 
227   /// binaryAnd - return a new range representing the possible values resulting
228   /// from a binary-and of a value in this range by a value in \p Other.
229   ConstantRange binaryAnd(const ConstantRange &Other) const;
230 
231   /// binaryOr - return a new range representing the possible values resulting
232   /// from a binary-or of a value in this range by a value in \p Other.
233   ConstantRange binaryOr(const ConstantRange &Other) const;
234 
235   /// shl - Return a new range representing the possible values resulting
236   /// from a left shift of a value in this range by a value in \p Other.
237   /// TODO: This isn't fully implemented yet.
238   ConstantRange shl(const ConstantRange &Other) const;
239 
240   /// lshr - Return a new range representing the possible values resulting
241   /// from a logical right shift of a value in this range and a value in
242   /// \p Other.
243   ConstantRange lshr(const ConstantRange &Other) const;
244 
245   /// inverse - Return a new range that is the logical not of the current set.
246   ///
247   ConstantRange inverse() const;
248 
249   /// print - Print out the bounds to a stream...
250   ///
251   void print(raw_ostream &OS) const;
252 
253   /// dump - Allow printing from a debugger easily...
254   ///
255   void dump() const;
256 };
257 
258 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
259   CR.print(OS);
260   return OS;
261 }
262 
263 } // End llvm namespace
264 
265 #endif
266