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1 : //===- 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_IR_CONSTANTRANGE_H
33 : #define LLVM_IR_CONSTANTRANGE_H
34 :
35 : #include "llvm/ADT/APInt.h"
36 : #include "llvm/IR/InstrTypes.h"
37 : #include "llvm/IR/Instruction.h"
38 : #include "llvm/Support/Compiler.h"
39 : #include <cstdint>
40 :
41 : namespace llvm {
42 :
43 : class MDNode;
44 : class raw_ostream;
45 :
46 : /// This class represents a range of values.
47 888316 : class LLVM_NODISCARD ConstantRange {
48 : APInt Lower, Upper;
49 :
50 : public:
51 : /// Initialize a full (the default) or empty set for the specified bit width.
52 : explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true);
53 :
54 : /// Initialize a range to hold the single specified value.
55 : ConstantRange(APInt Value);
56 :
57 : /// Initialize a range of values explicitly. This will assert out if
58 : /// Lower==Upper and Lower != Min or Max value for its type. It will also
59 : /// assert out if the two APInt's are not the same bit width.
60 : ConstantRange(APInt Lower, APInt Upper);
61 :
62 : /// Produce the smallest range such that all values that may satisfy the given
63 : /// predicate with any value contained within Other is contained in the
64 : /// returned range. Formally, this returns a superset of
65 : /// 'union over all y in Other . { x : icmp op x y is true }'. If the exact
66 : /// answer is not representable as a ConstantRange, the return value will be a
67 : /// proper superset of the above.
68 : ///
69 : /// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4)
70 : static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred,
71 : const ConstantRange &Other);
72 :
73 : /// Produce the largest range such that all values in the returned range
74 : /// satisfy the given predicate with all values contained within Other.
75 : /// Formally, this returns a subset of
76 : /// 'intersection over all y in Other . { x : icmp op x y is true }'. If the
77 : /// exact answer is not representable as a ConstantRange, the return value
78 : /// will be a proper subset of the above.
79 : ///
80 : /// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2)
81 : static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred,
82 : const ConstantRange &Other);
83 :
84 : /// Produce the exact range such that all values in the returned range satisfy
85 : /// the given predicate with any value contained within Other. Formally, this
86 : /// returns the exact answer when the superset of 'union over all y in Other
87 : /// is exactly same as the subset of intersection over all y in Other.
88 : /// { x : icmp op x y is true}'.
89 : ///
90 : /// Example: Pred = ult and Other = i8 3 returns [0, 3)
91 : static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred,
92 : const APInt &Other);
93 :
94 : /// Return the largest range containing all X such that "X BinOpC Y" is
95 : /// guaranteed not to wrap (overflow) for all Y in Other.
96 : ///
97 : /// NB! The returned set does *not* contain **all** possible values of X for
98 : /// which "X BinOpC Y" does not wrap -- some viable values of X may be
99 : /// missing, so you cannot use this to constrain X's range. E.g. in the
100 : /// fourth example, "(-2) + 1" is both nsw and nuw (so the "X" could be -2),
101 : /// but (-2) is not in the set returned.
102 : ///
103 : /// Examples:
104 : /// typedef OverflowingBinaryOperator OBO;
105 : /// #define MGNR makeGuaranteedNoWrapRegion
106 : /// MGNR(Add, [i8 1, 2), OBO::NoSignedWrap) == [-128, 127)
107 : /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap) == [0, -1)
108 : /// MGNR(Add, [i8 0, 1), OBO::NoUnsignedWrap) == Full Set
109 : /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap | OBO::NoSignedWrap)
110 : /// == [0,INT_MAX)
111 : /// MGNR(Add, [i8 -1, 6), OBO::NoSignedWrap) == [INT_MIN+1, INT_MAX-4)
112 : /// MGNR(Sub, [i8 1, 2), OBO::NoSignedWrap) == [-127, 128)
113 : /// MGNR(Sub, [i8 1, 2), OBO::NoUnsignedWrap) == [1, 0)
114 : /// MGNR(Sub, [i8 1, 2), OBO::NoUnsignedWrap | OBO::NoSignedWrap)
115 : /// == [1,INT_MAX)
116 : static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp,
117 : const ConstantRange &Other,
118 : unsigned NoWrapKind);
119 :
120 : /// Set up \p Pred and \p RHS such that
121 : /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if
122 : /// successful.
123 : bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const;
124 :
125 : /// Return the lower value for this range.
126 3528233 : const APInt &getLower() const { return Lower; }
127 :
128 : /// Return the upper value for this range.
129 6010380 : const APInt &getUpper() const { return Upper; }
130 :
131 : /// Get the bit width of this ConstantRange.
132 13888823 : uint32_t getBitWidth() const { return Lower.getBitWidth(); }
133 :
134 : /// Return true if this set contains all of the elements possible
135 : /// for this data-type.
136 : bool isFullSet() const;
137 :
138 : /// Return true if this set contains no members.
139 : bool isEmptySet() const;
140 :
141 : /// Return true if this set wraps around the top of the range.
142 : /// For example: [100, 8).
143 : bool isWrappedSet() const;
144 :
145 : /// Return true if this set wraps around the INT_MIN of
146 : /// its bitwidth. For example: i8 [120, 140).
147 : bool isSignWrappedSet() const;
148 :
149 : /// Return true if the specified value is in the set.
150 : bool contains(const APInt &Val) const;
151 :
152 : /// Return true if the other range is a subset of this one.
153 : bool contains(const ConstantRange &CR) const;
154 :
155 : /// If this set contains a single element, return it, otherwise return null.
156 3922489 : const APInt *getSingleElement() const {
157 11767467 : if (Upper == Lower + 1)
158 3617019 : return &Lower;
159 : return nullptr;
160 : }
161 :
162 : /// If this set contains all but a single element, return it, otherwise return
163 : /// null.
164 141925 : const APInt *getSingleMissingElement() const {
165 425775 : if (Lower == Upper + 1)
166 26584 : return &Upper;
167 : return nullptr;
168 : }
169 :
170 : /// Return true if this set contains exactly one member.
171 274620 : bool isSingleElement() const { return getSingleElement() != nullptr; }
172 :
173 : /// Return the number of elements in this set.
174 : APInt getSetSize() const;
175 :
176 : /// Compare set size of this range with the range CR.
177 : bool isSizeStrictlySmallerThan(const ConstantRange &CR) const;
178 :
179 : // Compare set size of this range with Value.
180 : bool isSizeLargerThan(uint64_t MaxSize) const;
181 :
182 : /// Return the largest unsigned value contained in the ConstantRange.
183 : APInt getUnsignedMax() const;
184 :
185 : /// Return the smallest unsigned value contained in the ConstantRange.
186 : APInt getUnsignedMin() const;
187 :
188 : /// Return the largest signed value contained in the ConstantRange.
189 : APInt getSignedMax() const;
190 :
191 : /// Return the smallest signed value contained in the ConstantRange.
192 : APInt getSignedMin() const;
193 :
194 : /// Return true if this range is equal to another range.
195 54380 : bool operator==(const ConstantRange &CR) const {
196 159515 : return Lower == CR.Lower && Upper == CR.Upper;
197 : }
198 : bool operator!=(const ConstantRange &CR) const {
199 1838 : return !operator==(CR);
200 : }
201 :
202 : /// Subtract the specified constant from the endpoints of this constant range.
203 : ConstantRange subtract(const APInt &CI) const;
204 :
205 : /// Subtract the specified range from this range (aka relative complement of
206 : /// the sets).
207 : ConstantRange difference(const ConstantRange &CR) const;
208 :
209 : /// Return the range that results from the intersection of
210 : /// this range with another range. The resultant range is guaranteed to
211 : /// include all elements contained in both input ranges, and to have the
212 : /// smallest possible set size that does so. Because there may be two
213 : /// intersections with the same set size, A.intersectWith(B) might not
214 : /// be equal to B.intersectWith(A).
215 : ConstantRange intersectWith(const ConstantRange &CR) const;
216 :
217 : /// Return the range that results from the union of this range
218 : /// with another range. The resultant range is guaranteed to include the
219 : /// elements of both sets, but may contain more. For example, [3, 9) union
220 : /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included
221 : /// in either set before.
222 : ConstantRange unionWith(const ConstantRange &CR) const;
223 :
224 : /// Return a new range representing the possible values resulting
225 : /// from an application of the specified cast operator to this range. \p
226 : /// BitWidth is the target bitwidth of the cast. For casts which don't
227 : /// change bitwidth, it must be the same as the source bitwidth. For casts
228 : /// which do change bitwidth, the bitwidth must be consistent with the
229 : /// requested cast and source bitwidth.
230 : ConstantRange castOp(Instruction::CastOps CastOp,
231 : uint32_t BitWidth) const;
232 :
233 : /// Return a new range in the specified integer type, which must
234 : /// be strictly larger than the current type. The returned range will
235 : /// correspond to the possible range of values if the source range had been
236 : /// zero extended to BitWidth.
237 : ConstantRange zeroExtend(uint32_t BitWidth) const;
238 :
239 : /// Return a new range in the specified integer type, which must
240 : /// be strictly larger than the current type. The returned range will
241 : /// correspond to the possible range of values if the source range had been
242 : /// sign extended to BitWidth.
243 : ConstantRange signExtend(uint32_t BitWidth) const;
244 :
245 : /// Return a new range in the specified integer type, which must be
246 : /// strictly smaller than the current type. The returned range will
247 : /// correspond to the possible range of values if the source range had been
248 : /// truncated to the specified type.
249 : ConstantRange truncate(uint32_t BitWidth) const;
250 :
251 : /// Make this range have the bit width given by \p BitWidth. The
252 : /// value is zero extended, truncated, or left alone to make it that width.
253 : ConstantRange zextOrTrunc(uint32_t BitWidth) const;
254 :
255 : /// Make this range have the bit width given by \p BitWidth. The
256 : /// value is sign extended, truncated, or left alone to make it that width.
257 : ConstantRange sextOrTrunc(uint32_t BitWidth) const;
258 :
259 : /// Return a new range representing the possible values resulting
260 : /// from an application of the specified binary operator to an left hand side
261 : /// of this range and a right hand side of \p Other.
262 : ConstantRange binaryOp(Instruction::BinaryOps BinOp,
263 : const ConstantRange &Other) const;
264 :
265 : /// Return a new range representing the possible values resulting
266 : /// from an addition of a value in this range and a value in \p Other.
267 : ConstantRange add(const ConstantRange &Other) const;
268 :
269 : /// Return a new range representing the possible values resulting from a
270 : /// known NSW addition of a value in this range and \p Other constant.
271 : ConstantRange addWithNoSignedWrap(const APInt &Other) const;
272 :
273 : /// Return a new range representing the possible values resulting
274 : /// from a subtraction of a value in this range and a value in \p Other.
275 : ConstantRange sub(const ConstantRange &Other) const;
276 :
277 : /// Return a new range representing the possible values resulting
278 : /// from a multiplication of a value in this range and a value in \p Other,
279 : /// treating both this and \p Other as unsigned ranges.
280 : ConstantRange multiply(const ConstantRange &Other) const;
281 :
282 : /// Return a new range representing the possible values resulting
283 : /// from a signed maximum of a value in this range and a value in \p Other.
284 : ConstantRange smax(const ConstantRange &Other) const;
285 :
286 : /// Return a new range representing the possible values resulting
287 : /// from an unsigned maximum of a value in this range and a value in \p Other.
288 : ConstantRange umax(const ConstantRange &Other) const;
289 :
290 : /// Return a new range representing the possible values resulting
291 : /// from a signed minimum of a value in this range and a value in \p Other.
292 : ConstantRange smin(const ConstantRange &Other) const;
293 :
294 : /// Return a new range representing the possible values resulting
295 : /// from an unsigned minimum of a value in this range and a value in \p Other.
296 : ConstantRange umin(const ConstantRange &Other) const;
297 :
298 : /// Return a new range representing the possible values resulting
299 : /// from an unsigned division of a value in this range and a value in
300 : /// \p Other.
301 : ConstantRange udiv(const ConstantRange &Other) const;
302 :
303 : /// Return a new range representing the possible values resulting
304 : /// from a binary-and of a value in this range by a value in \p Other.
305 : ConstantRange binaryAnd(const ConstantRange &Other) const;
306 :
307 : /// Return a new range representing the possible values resulting
308 : /// from a binary-or of a value in this range by a value in \p Other.
309 : ConstantRange binaryOr(const ConstantRange &Other) const;
310 :
311 : /// Return a new range representing the possible values resulting
312 : /// from a left shift of a value in this range by a value in \p Other.
313 : /// TODO: This isn't fully implemented yet.
314 : ConstantRange shl(const ConstantRange &Other) const;
315 :
316 : /// Return a new range representing the possible values resulting from a
317 : /// logical right shift of a value in this range and a value in \p Other.
318 : ConstantRange lshr(const ConstantRange &Other) const;
319 :
320 : /// Return a new range representing the possible values resulting from a
321 : /// arithmetic right shift of a value in this range and a value in \p Other.
322 : ConstantRange ashr(const ConstantRange &Other) const;
323 :
324 : /// Return a new range that is the logical not of the current set.
325 : ConstantRange inverse() const;
326 :
327 : /// Print out the bounds to a stream.
328 : void print(raw_ostream &OS) const;
329 :
330 : /// Allow printing from a debugger easily.
331 : void dump() const;
332 : };
333 :
334 : inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) {
335 0 : CR.print(OS);
336 : return OS;
337 : }
338 :
339 : /// Parse out a conservative ConstantRange from !range metadata.
340 : ///
341 : /// E.g. if RangeMD is !{i32 0, i32 10, i32 15, i32 20} then return [0, 20).
342 : ConstantRange getConstantRangeFromMetadata(const MDNode &RangeMD);
343 :
344 : } // end namespace llvm
345 :
346 : #endif // LLVM_IR_CONSTANTRANGE_H
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