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 /// 45 class ConstantRange { 46 APInt Lower, Upper; 47 48 // If we have move semantics, pass APInts by value and move them into place. 49 typedef APInt APIntMoveTy; 50 51 public: 52 /// Initialize a full (the default) or empty set for the specified bit width. 53 /// 54 explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true); 55 56 /// Initialize a range to hold the single specified value. 57 /// 58 ConstantRange(APIntMoveTy Value); 59 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); 64 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. 71 /// 72 /// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4) 73 static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred, 74 const ConstantRange &Other); 75 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. 82 /// 83 /// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2) 84 static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred, 85 const ConstantRange &Other); 86 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}'. 92 /// 93 /// Example: Pred = ult and Other = i8 3 returns [0, 3) 94 static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred, 95 const APInt &Other); 96 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. 99 /// 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. 105 /// 106 /// Examples: 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) 113 /// == [0,INT_MAX) 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); 118 119 /// Set up \p Pred and \p RHS such that 120 /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if 121 /// successful. 122 bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const; 123 124 /// Return the lower value for this range. 125 /// 126 const APInt &getLower() const { return Lower; } 127 128 /// Return the upper value for this range. 129 /// 130 const APInt &getUpper() const { return Upper; } 131 132 /// Get the bit width of this ConstantRange. 133 /// 134 uint32_t getBitWidth() const { return Lower.getBitWidth(); } 135 136 /// Return true if this set contains all of the elements possible 137 /// for this data-type. 138 /// 139 bool isFullSet() const; 140 141 /// Return true if this set contains no members. 142 /// 143 bool isEmptySet() const; 144 145 /// Return true if this set wraps around the top of the range. 146 /// For example: [100, 8). 147 /// 148 bool isWrappedSet() const; 149 150 /// Return true if this set wraps around the INT_MIN of 151 /// its bitwidth. For example: i8 [120, 140). 152 /// 153 bool isSignWrappedSet() const; 154 155 /// Return true if the specified value is in the set. 156 /// 157 bool contains(const APInt &Val) const; 158 159 /// Return true if the other range is a subset of this one. 160 /// 161 bool contains(const ConstantRange &CR) const; 162 163 /// If this set contains a single element, return it, otherwise return null. 164 /// 165 const APInt *getSingleElement() const { 166 if (Upper == Lower + 1) 167 return &Lower; 168 return nullptr; 169 } 170 171 /// If this set contains all but a single element, return it, otherwise return 172 /// null. 173 const APInt *getSingleMissingElement() const { 174 if (Lower == Upper + 1) 175 return &Upper; 176 return nullptr; 177 } 178 179 /// Return true if this set contains exactly one member. 180 /// 181 bool isSingleElement() const { return getSingleElement() != nullptr; } 182 183 /// Return the number of elements in this set. 184 /// 185 APInt getSetSize() const; 186 187 /// Compare set size of this range with the range CR. 188 /// 189 bool isSizeStrictlySmallerThanOf(const ConstantRange &CR) const; 190 191 /// Return the largest unsigned value contained in the ConstantRange. 192 /// 193 APInt getUnsignedMax() const; 194 195 /// Return the smallest unsigned value contained in the ConstantRange. 196 /// 197 APInt getUnsignedMin() const; 198 199 /// Return the largest signed value contained in the ConstantRange. 200 /// 201 APInt getSignedMax() const; 202 203 /// Return the smallest signed value contained in the ConstantRange. 204 /// 205 APInt getSignedMin() const; 206 207 /// Return true if this range is equal to another range. 208 /// 209 bool operator==(const ConstantRange &CR) const { 210 return Lower == CR.Lower && Upper == CR.Upper; 211 } 212 bool operator!=(const ConstantRange &CR) const { 213 return !operator==(CR); 214 } 215 216 /// Subtract the specified constant from the endpoints of this constant range. 217 ConstantRange subtract(const APInt &CI) const; 218 219 /// \brief Subtract the specified range from this range (aka relative 220 /// complement of the sets). 221 ConstantRange difference(const ConstantRange &CR) const; 222 223 /// Return the range that results from the intersection of 224 /// this range with another range. The resultant range is guaranteed to 225 /// include all elements contained in both input ranges, and to have the 226 /// smallest possible set size that does so. Because there may be two 227 /// intersections with the same set size, A.intersectWith(B) might not 228 /// be equal to B.intersectWith(A). 229 /// 230 ConstantRange intersectWith(const ConstantRange &CR) const; 231 232 /// Return the range that results from the union of this range 233 /// with another range. The resultant range is guaranteed to include the 234 /// elements of both sets, but may contain more. For example, [3, 9) union 235 /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included 236 /// in either set before. 237 /// 238 ConstantRange unionWith(const ConstantRange &CR) const; 239 240 /// Return a new range representing the possible values resulting 241 /// from an application of the specified cast operator to this range. \p 242 /// BitWidth is the target bitwidth of the cast. For casts which don't 243 /// change bitwidth, it must be the same as the source bitwidth. For casts 244 /// which do change bitwidth, the bitwidth must be consistent with the 245 /// requested cast and source bitwidth. 246 ConstantRange castOp(Instruction::CastOps CastOp, 247 uint32_t BitWidth) const; 248 249 /// Return a new range in the specified integer type, which must 250 /// be strictly larger than the current type. The returned range will 251 /// correspond to the possible range of values if the source range had been 252 /// zero extended to BitWidth. 253 ConstantRange zeroExtend(uint32_t BitWidth) const; 254 255 /// Return a new range in the specified integer type, which must 256 /// be strictly larger than the current type. The returned range will 257 /// correspond to the possible range of values if the source range had been 258 /// sign extended to BitWidth. 259 ConstantRange signExtend(uint32_t BitWidth) const; 260 261 /// Return a new range in the specified integer type, which must be 262 /// strictly smaller than the current type. The returned range will 263 /// correspond to the possible range of values if the source range had been 264 /// truncated to the specified type. 265 ConstantRange truncate(uint32_t BitWidth) const; 266 267 /// Make this range have the bit width given by \p BitWidth. The 268 /// value is zero extended, truncated, or left alone to make it that width. 269 ConstantRange zextOrTrunc(uint32_t BitWidth) const; 270 271 /// Make this range have the bit width given by \p BitWidth. The 272 /// value is sign extended, truncated, or left alone to make it that width. 273 ConstantRange sextOrTrunc(uint32_t BitWidth) const; 274 275 /// Return a new range representing the possible values resulting 276 /// from an application of the specified binary operator to an left hand side 277 /// of this range and a right hand side of \p Other. 278 ConstantRange binaryOp(Instruction::BinaryOps BinOp, 279 const ConstantRange &Other) const; 280 281 /// Return a new range representing the possible values resulting 282 /// from an addition of a value in this range and a value in \p Other. 283 ConstantRange add(const ConstantRange &Other) const; 284 285 /// Return a new range representing the possible values resulting from a 286 /// known NSW addition of a value in this range and \p Other constant. 287 ConstantRange addWithNoSignedWrap(const APInt &Other) const; 288 289 /// Return a new range representing the possible values resulting 290 /// from a subtraction of a value in this range and a value in \p Other. 291 ConstantRange sub(const ConstantRange &Other) const; 292 293 /// Return a new range representing the possible values resulting 294 /// from a multiplication of a value in this range and a value in \p Other, 295 /// treating both this and \p Other as unsigned ranges. 296 ConstantRange multiply(const ConstantRange &Other) const; 297 298 /// Return a new range representing the possible values resulting 299 /// from a signed maximum of a value in this range and a value in \p Other. 300 ConstantRange smax(const ConstantRange &Other) const; 301 302 /// Return a new range representing the possible values resulting 303 /// from an unsigned maximum of a value in this range and a value in \p Other. 304 ConstantRange umax(const ConstantRange &Other) const; 305 306 /// Return a new range representing the possible values resulting 307 /// from a signed minimum of a value in this range and a value in \p Other. 308 ConstantRange smin(const ConstantRange &Other) const; 309 310 /// Return a new range representing the possible values resulting 311 /// from an unsigned minimum of a value in this range and a value in \p Other. 312 ConstantRange umin(const ConstantRange &Other) const; 313 314 /// Return a new range representing the possible values resulting 315 /// from an unsigned division of a value in this range and a value in 316 /// \p Other. 317 ConstantRange udiv(const ConstantRange &Other) const; 318 319 /// Return a new range representing the possible values resulting 320 /// from a binary-and of a value in this range by a value in \p Other. 321 ConstantRange binaryAnd(const ConstantRange &Other) const; 322 323 /// Return a new range representing the possible values resulting 324 /// from a binary-or of a value in this range by a value in \p Other. 325 ConstantRange binaryOr(const ConstantRange &Other) const; 326 327 /// Return a new range representing the possible values resulting 328 /// from a left shift of a value in this range by a value in \p Other. 329 /// TODO: This isn't fully implemented yet. 330 ConstantRange shl(const ConstantRange &Other) const; 331 332 /// Return a new range representing the possible values resulting from a 333 /// logical right shift of a value in this range and a value in \p Other. 334 ConstantRange lshr(const ConstantRange &Other) const; 335 336 /// Return a new range that is the logical not of the current set. 337 /// 338 ConstantRange inverse() const; 339 340 /// Print out the bounds to a stream. 341 /// 342 void print(raw_ostream &OS) const; 343 344 /// Allow printing from a debugger easily. 345 /// 346 void dump() const; 347 }; 348 349 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) { 350 CR.print(OS); 351 return OS; 352 } 353 354 /// Parse out a conservative ConstantRange from !range metadata. 355 /// 356 /// E.g. if RangeMD is !{i32 0, i32 10, i32 15, i32 20} then return [0, 20). 357 ConstantRange getConstantRangeFromMetadata(const MDNode &RangeMD); 358 359 } // End llvm namespace 360 361 #endif 362
