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