1 //===- ConstantRange.h - Represent a range ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
17 // [F, F) = {} = Empty set
20 // [T, T) = {F, T} = Full set
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
27 // Note that ConstantRange can be used to represent either signed or
30 //===----------------------------------------------------------------------===//
32 #ifndef LLVM_IR_CONSTANTRANGE_H
33 #define LLVM_IR_CONSTANTRANGE_H
35 #include "llvm/ADT/APInt.h"
36 #include "llvm/IR/InstrTypes.h"
37 #include "llvm/Support/DataTypes.h"
43 /// This class represents a range of values.
48 // If we have move semantics, pass APInts by value and move them into place.
49 typedef APInt APIntMoveTy;
52 /// Initialize a full (the default) or empty set for the specified bit width.
54 explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
56 /// Initialize a range to hold the single specified value.
58 ConstantRange(APIntMoveTy Value);
60 /// @brief Initialize a range of values explicitly. This will assert out if
61 /// Lower==Upper and Lower != Min or Max value for its type. It will also
62 /// assert out if the two APInt's are not the same bit width.
63 ConstantRange(APIntMoveTy Lower, APIntMoveTy Upper);
65 /// Produce the smallest range such that all values that may satisfy the given
66 /// predicate with any value contained within Other is contained in the
67 /// returned range. Formally, this returns a superset of
68 /// 'union over all y in Other . { x : icmp op x y is true }'. If the exact
69 /// answer is not representable as a ConstantRange, the return value will be a
70 /// proper superset of the above.
72 /// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4)
73 static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred,
74 const ConstantRange &Other);
76 /// Produce the largest range such that all values in the returned range
77 /// satisfy the given predicate with all values contained within Other.
78 /// Formally, this returns a subset of
79 /// 'intersection over all y in Other . { x : icmp op x y is true }'. If the
80 /// exact answer is not representable as a ConstantRange, the return value
81 /// will be a proper subset of the above.
83 /// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2)
84 static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
85 const ConstantRange &Other);
87 /// Produce the exact range such that all values in the returned range satisfy
88 /// the given predicate with any value contained within Other. Formally, this
89 /// returns the exact answer when the superset of 'union over all y in Other
90 /// is exactly same as the subset of intersection over all y in Other.
91 /// { x : icmp op x y is true}'.
93 /// Example: Pred = ult and Other = i8 3 returns [0, 3)
94 static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred,
97 /// Return the largest range containing all X such that "X BinOpC Y" is
98 /// guaranteed not to wrap (overflow) for all Y in Other.
100 /// NB! The returned set does *not* contain **all** possible values of X for
101 /// which "X BinOpC Y" does not wrap -- some viable values of X may be
102 /// missing, so you cannot use this to contrain X's range. E.g. in the last
103 /// example, "(-2) + 1" is both nsw and nuw (so the "X" could be -2), but (-2)
104 /// is not in the set returned.
107 /// typedef OverflowingBinaryOperator OBO;
108 /// #define MGNR makeGuaranteedNoWrapRegion
109 /// MGNR(Add, [i8 1, 2), OBO::NoSignedWrap) == [-128, 127)
110 /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap) == [0, -1)
111 /// MGNR(Add, [i8 0, 1), OBO::NoUnsignedWrap) == Full Set
112 /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap | OBO::NoSignedWrap)
114 /// MGNR(Add, [i8 -1, 6), OBO::NoSignedWrap) == [INT_MIN+1, INT_MAX-4)
115 static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
116 const ConstantRange &Other,
117 unsigned NoWrapKind);
119 /// Set up \p Pred and \p RHS such that
120 /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if
122 bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const;
124 /// Return the lower value for this range.
126 const APInt &getLower() const { return Lower; }
128 /// Return the upper value for this range.
130 const APInt &getUpper() const { return Upper; }
132 /// Get the bit width of this ConstantRange.
134 uint32_t getBitWidth() const { return Lower.getBitWidth(); }
136 /// Return true if this set contains all of the elements possible
137 /// for this data-type.
139 bool isFullSet() const;
141 /// Return true if this set contains no members.
143 bool isEmptySet() const;
145 /// Return true if this set wraps around the top of the range.
146 /// For example: [100, 8).
148 bool isWrappedSet() const;
150 /// Return true if this set wraps around the INT_MIN of
151 /// its bitwidth. For example: i8 [120, 140).
153 bool isSignWrappedSet() const;
155 /// Return true if the specified value is in the set.
157 bool contains(const APInt &Val) const;
159 /// Return true if the other range is a subset of this one.
161 bool contains(const ConstantRange &CR) const;
163 /// If this set contains a single element, return it, otherwise return null.
165 const APInt *getSingleElement() const {
166 if (Upper == Lower + 1)
171 /// If this set contains all but a single element, return it, otherwise return
173 const APInt *getSingleMissingElement() const {
174 if (Lower == Upper + 1)
179 /// Return true if this set contains exactly one member.
181 bool isSingleElement() const { return getSingleElement() != nullptr; }
183 /// Return the number of elements in this set.
185 APInt getSetSize() const;
187 /// Return the largest unsigned value contained in the ConstantRange.
189 APInt getUnsignedMax() const;
191 /// Return the smallest unsigned value contained in the ConstantRange.
193 APInt getUnsignedMin() const;
195 /// Return the largest signed value contained in the ConstantRange.
197 APInt getSignedMax() const;
199 /// Return the smallest signed value contained in the ConstantRange.
201 APInt getSignedMin() const;
203 /// Return true if this range is equal to another range.
205 bool operator==(const ConstantRange &CR) const {
206 return Lower == CR.Lower && Upper == CR.Upper;
208 bool operator!=(const ConstantRange &CR) const {
209 return !operator==(CR);
212 /// Subtract the specified constant from the endpoints of this constant range.
213 ConstantRange subtract(const APInt &CI) const;
215 /// \brief Subtract the specified range from this range (aka relative
216 /// complement of the sets).
217 ConstantRange difference(const ConstantRange &CR) const;
219 /// Return the range that results from the intersection of
220 /// this range with another range. The resultant range is guaranteed to
221 /// include all elements contained in both input ranges, and to have the
222 /// smallest possible set size that does so. Because there may be two
223 /// intersections with the same set size, A.intersectWith(B) might not
224 /// be equal to B.intersectWith(A).
226 ConstantRange intersectWith(const ConstantRange &CR) const;
228 /// Return the range that results from the union of this range
229 /// with another range. The resultant range is guaranteed to include the
230 /// elements of both sets, but may contain more. For example, [3, 9) union
231 /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
232 /// in either set before.
234 ConstantRange unionWith(const ConstantRange &CR) const;
236 /// Return a new range representing the possible values resulting
237 /// from an application of the specified cast operator to this range. \p
238 /// BitWidth is the target bitwidth of the cast. For casts which don't
239 /// change bitwidth, it must be the same as the source bitwidth. For casts
240 /// which do change bitwidth, the bitwidth must be consistent with the
241 /// requested cast and source bitwidth.
242 ConstantRange castOp(Instruction::CastOps CastOp,
243 uint32_t BitWidth) const;
245 /// Return a new range in the specified integer type, which must
246 /// be strictly larger than the current type. The returned range will
247 /// correspond to the possible range of values if the source range had been
248 /// zero extended to BitWidth.
249 ConstantRange zeroExtend(uint32_t BitWidth) const;
251 /// Return a new range in the specified integer type, which must
252 /// be strictly larger than the current type. The returned range will
253 /// correspond to the possible range of values if the source range had been
254 /// sign extended to BitWidth.
255 ConstantRange signExtend(uint32_t BitWidth) const;
257 /// Return a new range in the specified integer type, which must be
258 /// strictly smaller than the current type. The returned range will
259 /// correspond to the possible range of values if the source range had been
260 /// truncated to the specified type.
261 ConstantRange truncate(uint32_t BitWidth) const;
263 /// Make this range have the bit width given by \p BitWidth. The
264 /// value is zero extended, truncated, or left alone to make it that width.
265 ConstantRange zextOrTrunc(uint32_t BitWidth) const;
267 /// Make this range have the bit width given by \p BitWidth. The
268 /// value is sign extended, truncated, or left alone to make it that width.
269 ConstantRange sextOrTrunc(uint32_t BitWidth) const;
271 /// Return a new range representing the possible values resulting
272 /// from an application of the specified binary operator to an left hand side
273 /// of this range and a right hand side of \p Other.
274 ConstantRange binaryOp(Instruction::BinaryOps BinOp,
275 const ConstantRange &Other) const;
277 /// Return a new range representing the possible values resulting
278 /// from an addition of a value in this range and a value in \p Other.
279 ConstantRange add(const ConstantRange &Other) const;
281 /// Return a new range representing the possible values resulting from a
282 /// known NSW addition of a value in this range and \p Other constant.
283 ConstantRange addWithNoSignedWrap(const APInt &Other) const;
285 /// Return a new range representing the possible values resulting
286 /// from a subtraction of a value in this range and a value in \p Other.
287 ConstantRange sub(const ConstantRange &Other) const;
289 /// Return a new range representing the possible values resulting
290 /// from a multiplication of a value in this range and a value in \p Other,
291 /// treating both this and \p Other as unsigned ranges.
292 ConstantRange multiply(const ConstantRange &Other) const;
294 /// Return a new range representing the possible values resulting
295 /// from a signed maximum of a value in this range and a value in \p Other.
296 ConstantRange smax(const ConstantRange &Other) const;
298 /// Return a new range representing the possible values resulting
299 /// from an unsigned maximum of a value in this range and a value in \p Other.
300 ConstantRange umax(const ConstantRange &Other) const;
302 /// Return a new range representing the possible values resulting
303 /// from a signed minimum of a value in this range and a value in \p Other.
304 ConstantRange smin(const ConstantRange &Other) const;
306 /// Return a new range representing the possible values resulting
307 /// from an unsigned minimum of a value in this range and a value in \p Other.
308 ConstantRange umin(const ConstantRange &Other) const;
310 /// Return a new range representing the possible values resulting
311 /// from an unsigned division of a value in this range and a value in
313 ConstantRange udiv(const ConstantRange &Other) const;
315 /// Return a new range representing the possible values resulting
316 /// from a binary-and of a value in this range by a value in \p Other.
317 ConstantRange binaryAnd(const ConstantRange &Other) const;
319 /// Return a new range representing the possible values resulting
320 /// from a binary-or of a value in this range by a value in \p Other.
321 ConstantRange binaryOr(const ConstantRange &Other) const;
323 /// Return a new range representing the possible values resulting
324 /// from a left shift of a value in this range by a value in \p Other.
325 /// TODO: This isn't fully implemented yet.
326 ConstantRange shl(const ConstantRange &Other) const;
328 /// Return a new range representing the possible values resulting from a
329 /// logical right shift of a value in this range and a value in \p Other.
330 ConstantRange lshr(const ConstantRange &Other) const;
332 /// Return a new range that is the logical not of the current set.
334 ConstantRange inverse() const;
336 /// Print out the bounds to a stream.
338 void print(raw_ostream &OS) const;
340 /// Allow printing from a debugger easily.
345 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
350 /// Parse out a conservative ConstantRange from !range metadata.
352 /// E.g. if RangeMD is !{i32 0, i32 10, i32 15, i32 20} then return [0, 20).
353 ConstantRange getConstantRangeFromMetadata(const MDNode &RangeMD);
355 } // End llvm namespace