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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_CONSTANTRANGE_H
33 #define LLVM_SUPPORT_CONSTANTRANGE_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 #if LLVM_HAS_RVALUE_REFERENCES
46   // If we have move semantics, pass APInts by value and move them into place.
47   typedef APInt APIntMoveTy;
48 #else
49   // Otherwise pass by const ref to save one copy.
50   typedef const APInt &APIntMoveTy;
51 #endif
52 
53 public:
54   /// Initialize a full (the default) or empty set for the specified bit width.
55   ///
56   explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
57 
58   /// Initialize a range to hold the single specified value.
59   ///
60   ConstantRange(APIntMoveTy Value);
61 
62   /// @brief Initialize a range of values explicitly. This will assert out if
63   /// Lower==Upper and Lower != Min or Max value for its type. It will also
64   /// assert out if the two APInt's are not the same bit width.
65   ConstantRange(APIntMoveTy Lower, APIntMoveTy Upper);
66 
67   /// makeICmpRegion - Produce the smallest range that contains all values that
68   /// might satisfy the comparison specified by Pred when compared to any value
69   /// contained within Other.
70   ///
71   /// Solves for range X in 'for all x in X, there exists a y in Y such that
72   /// icmp op x, y is true'. Every value that might make the comparison true
73   /// is included in the resulting range.
74   static ConstantRange makeICmpRegion(unsigned Pred,
75                                       const ConstantRange &Other);
76 
77   /// getLower - Return the lower value for this range...
78   ///
getLower()79   const APInt &getLower() const { return Lower; }
80 
81   /// getUpper - Return the upper value for this range...
82   ///
getUpper()83   const APInt &getUpper() const { return Upper; }
84 
85   /// getBitWidth - get the bit width of this ConstantRange
86   ///
getBitWidth()87   uint32_t getBitWidth() const { return Lower.getBitWidth(); }
88 
89   /// isFullSet - Return true if this set contains all of the elements possible
90   /// for this data-type
91   ///
92   bool isFullSet() const;
93 
94   /// isEmptySet - Return true if this set contains no members.
95   ///
96   bool isEmptySet() const;
97 
98   /// isWrappedSet - Return true if this set wraps around the top of the range,
99   /// for example: [100, 8)
100   ///
101   bool isWrappedSet() const;
102 
103   /// isSignWrappedSet - Return true if this set wraps around the INT_MIN of
104   /// its bitwidth, for example: i8 [120, 140).
105   ///
106   bool isSignWrappedSet() const;
107 
108   /// contains - Return true if the specified value is in the set.
109   ///
110   bool contains(const APInt &Val) const;
111 
112   /// contains - Return true if the other range is a subset of this one.
113   ///
114   bool contains(const ConstantRange &CR) const;
115 
116   /// getSingleElement - If this set contains a single element, return it,
117   /// otherwise return null.
118   ///
getSingleElement()119   const APInt *getSingleElement() const {
120     if (Upper == Lower + 1)
121       return &Lower;
122     return 0;
123   }
124 
125   /// isSingleElement - Return true if this set contains exactly one member.
126   ///
isSingleElement()127   bool isSingleElement() const { return getSingleElement() != 0; }
128 
129   /// getSetSize - Return the number of elements in this set.
130   ///
131   APInt getSetSize() const;
132 
133   /// getUnsignedMax - Return the largest unsigned value contained in the
134   /// ConstantRange.
135   ///
136   APInt getUnsignedMax() const;
137 
138   /// getUnsignedMin - Return the smallest unsigned value contained in the
139   /// ConstantRange.
140   ///
141   APInt getUnsignedMin() const;
142 
143   /// getSignedMax - Return the largest signed value contained in the
144   /// ConstantRange.
145   ///
146   APInt getSignedMax() const;
147 
148   /// getSignedMin - Return the smallest signed value contained in the
149   /// ConstantRange.
150   ///
151   APInt getSignedMin() const;
152 
153   /// operator== - Return true if this range is equal to another range.
154   ///
155   bool operator==(const ConstantRange &CR) const {
156     return Lower == CR.Lower && Upper == CR.Upper;
157   }
158   bool operator!=(const ConstantRange &CR) const {
159     return !operator==(CR);
160   }
161 
162   /// subtract - Subtract the specified constant from the endpoints of this
163   /// constant range.
164   ConstantRange subtract(const APInt &CI) const;
165 
166   /// \brief Subtract the specified range from this range (aka relative
167   /// complement of the sets).
168   ConstantRange difference(const ConstantRange &CR) const;
169 
170   /// intersectWith - Return the range that results from the intersection of
171   /// this range with another range.  The resultant range is guaranteed to
172   /// include all elements contained in both input ranges, and to have the
173   /// smallest possible set size that does so.  Because there may be two
174   /// intersections with the same set size, A.intersectWith(B) might not
175   /// be equal to B.intersectWith(A).
176   ///
177   ConstantRange intersectWith(const ConstantRange &CR) const;
178 
179   /// unionWith - Return the range that results from the union of this range
180   /// with another range.  The resultant range is guaranteed to include the
181   /// elements of both sets, but may contain more.  For example, [3, 9) union
182   /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
183   /// in either set before.
184   ///
185   ConstantRange unionWith(const ConstantRange &CR) const;
186 
187   /// zeroExtend - Return a new range in the specified integer type, which must
188   /// be strictly larger than the current type.  The returned range will
189   /// correspond to the possible range of values if the source range had been
190   /// zero extended to BitWidth.
191   ConstantRange zeroExtend(uint32_t BitWidth) const;
192 
193   /// signExtend - Return a new range in the specified integer type, which must
194   /// be strictly larger than the current type.  The returned range will
195   /// correspond to the possible range of values if the source range had been
196   /// sign extended to BitWidth.
197   ConstantRange signExtend(uint32_t BitWidth) const;
198 
199   /// truncate - Return a new range in the specified integer type, which must be
200   /// strictly smaller than the current type.  The returned range will
201   /// correspond to the possible range of values if the source range had been
202   /// truncated to the specified type.
203   ConstantRange truncate(uint32_t BitWidth) const;
204 
205   /// zextOrTrunc - make this range have the bit width given by \p BitWidth. The
206   /// value is zero extended, truncated, or left alone to make it that width.
207   ConstantRange zextOrTrunc(uint32_t BitWidth) const;
208 
209   /// sextOrTrunc - make this range have the bit width given by \p BitWidth. The
210   /// value is sign extended, truncated, or left alone to make it that width.
211   ConstantRange sextOrTrunc(uint32_t BitWidth) const;
212 
213   /// add - Return a new range representing the possible values resulting
214   /// from an addition of a value in this range and a value in \p Other.
215   ConstantRange add(const ConstantRange &Other) const;
216 
217   /// sub - Return a new range representing the possible values resulting
218   /// from a subtraction of a value in this range and a value in \p Other.
219   ConstantRange sub(const ConstantRange &Other) const;
220 
221   /// multiply - Return a new range representing the possible values resulting
222   /// from a multiplication of a value in this range and a value in \p Other.
223   /// TODO: This isn't fully implemented yet.
224   ConstantRange multiply(const ConstantRange &Other) const;
225 
226   /// smax - Return a new range representing the possible values resulting
227   /// from a signed maximum of a value in this range and a value in \p Other.
228   ConstantRange smax(const ConstantRange &Other) const;
229 
230   /// umax - Return a new range representing the possible values resulting
231   /// from an unsigned maximum of a value in this range and a value in \p Other.
232   ConstantRange umax(const ConstantRange &Other) const;
233 
234   /// udiv - Return a new range representing the possible values resulting
235   /// from an unsigned division of a value in this range and a value in
236   /// \p Other.
237   ConstantRange udiv(const ConstantRange &Other) const;
238 
239   /// binaryAnd - return a new range representing the possible values resulting
240   /// from a binary-and of a value in this range by a value in \p Other.
241   ConstantRange binaryAnd(const ConstantRange &Other) const;
242 
243   /// binaryOr - return a new range representing the possible values resulting
244   /// from a binary-or of a value in this range by a value in \p Other.
245   ConstantRange binaryOr(const ConstantRange &Other) const;
246 
247   /// shl - Return a new range representing the possible values resulting
248   /// from a left shift of a value in this range by a value in \p Other.
249   /// TODO: This isn't fully implemented yet.
250   ConstantRange shl(const ConstantRange &Other) const;
251 
252   /// lshr - Return a new range representing the possible values resulting
253   /// from a logical right shift of a value in this range and a value in
254   /// \p Other.
255   ConstantRange lshr(const ConstantRange &Other) const;
256 
257   /// inverse - Return a new range that is the logical not of the current set.
258   ///
259   ConstantRange inverse() const;
260 
261   /// print - Print out the bounds to a stream...
262   ///
263   void print(raw_ostream &OS) const;
264 
265   /// dump - Allow printing from a debugger easily...
266   ///
267   void dump() const;
268 };
269 
270 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
271   CR.print(OS);
272   return OS;
273 }
274 
275 } // End llvm namespace
276 
277 #endif
278