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 /// This class represents a range of values. 42 /// 43 class ConstantRange { 44 APInt Lower, Upper; 45 46 // If we have move semantics, pass APInts by value and move them into place. 47 typedef APInt APIntMoveTy; 48 49 public: 50 /// Initialize a full (the default) or empty set for the specified bit width. 51 /// 52 explicit ConstantRange(uint32_t BitWidth, bool isFullSet = true); 53 54 /// Initialize a range to hold the single specified value. 55 /// 56 ConstantRange(APIntMoveTy Value); 57 58 /// @brief Initialize a range of values explicitly. This will assert out if 59 /// Lower==Upper and Lower != Min or Max value for its type. It will also 60 /// assert out if the two APInt's are not the same bit width. 61 ConstantRange(APIntMoveTy Lower, APIntMoveTy Upper); 62 63 /// Produce the smallest range such that all values that may satisfy the given 64 /// predicate with any value contained within Other is contained in the 65 /// returned range. Formally, this returns a superset of 66 /// 'union over all y in Other . { x : icmp op x y is true }'. If the exact 67 /// answer is not representable as a ConstantRange, the return value will be a 68 /// proper superset of the above. 69 /// 70 /// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4) 71 static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred, 72 const ConstantRange &Other); 73 74 /// Produce the largest range such that all values in the returned range 75 /// satisfy the given predicate with all values contained within Other. 76 /// Formally, this returns a subset of 77 /// 'intersection over all y in Other . { x : icmp op x y is true }'. If the 78 /// exact answer is not representable as a ConstantRange, the return value 79 /// will be a proper subset of the above. 80 /// 81 /// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2) 82 static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred, 83 const ConstantRange &Other); 84 85 /// Produce the exact range such that all values in the returned range satisfy 86 /// the given predicate with any value contained within Other. Formally, this 87 /// returns the exact answer when the superset of 'union over all y in Other 88 /// is exactly same as the subset of intersection over all y in Other. 89 /// { x : icmp op x y is true}'. 90 /// 91 /// Example: Pred = ult and Other = i8 3 returns [0, 3) 92 static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred, 93 const APInt &Other); 94 95 /// Return the largest range containing all X such that "X BinOpC Y" is 96 /// guaranteed not to wrap (overflow) for all Y in Other. 97 /// 98 /// NB! The returned set does *not* contain **all** possible values of X for 99 /// which "X BinOpC Y" does not wrap -- some viable values of X may be 100 /// missing, so you cannot use this to contrain X's range. E.g. in the last 101 /// example, "(-2) + 1" is both nsw and nuw (so the "X" could be -2), but (-2) 102 /// is not in the set returned. 103 /// 104 /// Examples: 105 /// typedef OverflowingBinaryOperator OBO; 106 /// #define MGNR makeGuaranteedNoWrapRegion 107 /// MGNR(Add, [i8 1, 2), OBO::NoSignedWrap) == [-128, 127) 108 /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap) == [0, -1) 109 /// MGNR(Add, [i8 0, 1), OBO::NoUnsignedWrap) == Full Set 110 /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap | OBO::NoSignedWrap) 111 /// == [0,INT_MAX) 112 /// MGNR(Add, [i8 -1, 6), OBO::NoSignedWrap) == [INT_MIN+1, INT_MAX-4) 113 static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp, 114 const ConstantRange &Other, 115 unsigned NoWrapKind); 116 117 /// Set up \p Pred and \p RHS such that 118 /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if 119 /// successful. 120 bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const; 121 122 /// Return the lower value for this range. 123 /// 124 const APInt &getLower() const { return Lower; } 125 126 /// Return the upper value for this range. 127 /// 128 const APInt &getUpper() const { return Upper; } 129 130 /// Get the bit width of this ConstantRange. 131 /// 132 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 /// 137 bool isFullSet() const; 138 139 /// Return true if this set contains no members. 140 /// 141 bool isEmptySet() const; 142 143 /// Return true if this set wraps around the top of the range. 144 /// For example: [100, 8). 145 /// 146 bool isWrappedSet() const; 147 148 /// Return true if this set wraps around the INT_MIN of 149 /// its bitwidth. For example: i8 [120, 140). 150 /// 151 bool isSignWrappedSet() const; 152 153 /// Return true if the specified value is in the set. 154 /// 155 bool contains(const APInt &Val) const; 156 157 /// Return true if the other range is a subset of this one. 158 /// 159 bool contains(const ConstantRange &CR) const; 160 161 /// If this set contains a single element, return it, otherwise return null. 162 /// 163 const APInt *getSingleElement() const { 164 if (Upper == Lower + 1) 165 return &Lower; 166 return nullptr; 167 } 168 169 /// Return true if this set contains exactly one member. 170 /// 171 bool isSingleElement() const { return getSingleElement() != nullptr; } 172 173 /// Return the number of elements in this set. 174 /// 175 APInt getSetSize() const; 176 177 /// Return the largest unsigned value contained in the ConstantRange. 178 /// 179 APInt getUnsignedMax() const; 180 181 /// Return the smallest unsigned value contained in the ConstantRange. 182 /// 183 APInt getUnsignedMin() const; 184 185 /// Return the largest signed value contained in the ConstantRange. 186 /// 187 APInt getSignedMax() const; 188 189 /// Return the smallest signed value contained in the ConstantRange. 190 /// 191 APInt getSignedMin() const; 192 193 /// Return true if this range is equal to another range. 194 /// 195 bool operator==(const ConstantRange &CR) const { 196 return Lower == CR.Lower && Upper == CR.Upper; 197 } 198 bool operator!=(const ConstantRange &CR) const { 199 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 /// \brief Subtract the specified range from this range (aka relative 206 /// complement of 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 /// 216 ConstantRange intersectWith(const ConstantRange &CR) const; 217 218 /// Return the range that results from the union of this range 219 /// with another range. The resultant range is guaranteed to include the 220 /// elements of both sets, but may contain more. For example, [3, 9) union 221 /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included 222 /// in either set before. 223 /// 224 ConstantRange unionWith(const ConstantRange &CR) 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 addition of a value in this range and a value in \p Other. 254 ConstantRange add(const ConstantRange &Other) const; 255 256 /// Return a new range representing the possible values resulting 257 /// from a subtraction of a value in this range and a value in \p Other. 258 ConstantRange sub(const ConstantRange &Other) const; 259 260 /// Return a new range representing the possible values resulting 261 /// from a multiplication of a value in this range and a value in \p Other, 262 /// treating both this and \p Other as unsigned ranges. 263 ConstantRange multiply(const ConstantRange &Other) const; 264 265 /// Return a new range representing the possible values resulting 266 /// from a signed maximum of a value in this range and a value in \p Other. 267 ConstantRange smax(const ConstantRange &Other) const; 268 269 /// Return a new range representing the possible values resulting 270 /// from an unsigned maximum of a value in this range and a value in \p Other. 271 ConstantRange umax(const ConstantRange &Other) const; 272 273 /// Return a new range representing the possible values resulting 274 /// from a signed minimum of a value in this range and a value in \p Other. 275 ConstantRange smin(const ConstantRange &Other) const; 276 277 /// Return a new range representing the possible values resulting 278 /// from an unsigned minimum of a value in this range and a value in \p Other. 279 ConstantRange umin(const ConstantRange &Other) const; 280 281 /// Return a new range representing the possible values resulting 282 /// from an unsigned division of a value in this range and a value in 283 /// \p Other. 284 ConstantRange udiv(const ConstantRange &Other) const; 285 286 /// Return a new range representing the possible values resulting 287 /// from a binary-and of a value in this range by a value in \p Other. 288 ConstantRange binaryAnd(const ConstantRange &Other) const; 289 290 /// Return a new range representing the possible values resulting 291 /// from a binary-or of a value in this range by a value in \p Other. 292 ConstantRange binaryOr(const ConstantRange &Other) const; 293 294 /// Return a new range representing the possible values resulting 295 /// from a left shift of a value in this range by a value in \p Other. 296 /// TODO: This isn't fully implemented yet. 297 ConstantRange shl(const ConstantRange &Other) const; 298 299 /// Return a new range representing the possible values resulting from a 300 /// logical right shift of a value in this range and a value in \p Other. 301 ConstantRange lshr(const ConstantRange &Other) const; 302 303 /// Return a new range that is the logical not of the current set. 304 /// 305 ConstantRange inverse() const; 306 307 /// Print out the bounds to a stream. 308 /// 309 void print(raw_ostream &OS) const; 310 311 /// Allow printing from a debugger easily. 312 /// 313 void dump() const; 314 }; 315 316 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) { 317 CR.print(OS); 318 return OS; 319 } 320 321 } // End llvm namespace 322 323 #endif 324
