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 /// Return the largest range containing all X such that "X BinOpC C" does not 86 /// wrap (overflow). 87 /// 88 /// Example: 89 /// typedef OverflowingBinaryOperator OBO; 90 /// makeNoWrapRegion(Add, i8 1, OBO::NoSignedWrap) == [-128, 127) 91 /// makeNoWrapRegion(Add, i8 1, OBO::NoUnsignedWrap) == [0, -1) 92 /// makeNoWrapRegion(Add, i8 0, OBO::NoUnsignedWrap) == Full Set 93 static ConstantRange makeNoWrapRegion(Instruction::BinaryOps BinOp, 94 const APInt &C, unsigned NoWrapKind); 95 96 /// Return the lower value for this range. 97 /// 98 const APInt &getLower() const { return Lower; } 99 100 /// Return the upper value for this range. 101 /// 102 const APInt &getUpper() const { return Upper; } 103 104 /// Get the bit width of this ConstantRange. 105 /// 106 uint32_t getBitWidth() const { return Lower.getBitWidth(); } 107 108 /// Return true if this set contains all of the elements possible 109 /// for this data-type. 110 /// 111 bool isFullSet() const; 112 113 /// Return true if this set contains no members. 114 /// 115 bool isEmptySet() const; 116 117 /// Return true if this set wraps around the top of the range. 118 /// For example: [100, 8). 119 /// 120 bool isWrappedSet() const; 121 122 /// Return true if this set wraps around the INT_MIN of 123 /// its bitwidth. For example: i8 [120, 140). 124 /// 125 bool isSignWrappedSet() const; 126 127 /// Return true if the specified value is in the set. 128 /// 129 bool contains(const APInt &Val) const; 130 131 /// Return true if the other range is a subset of this one. 132 /// 133 bool contains(const ConstantRange &CR) const; 134 135 /// If this set contains a single element, return it, otherwise return null. 136 /// 137 const APInt *getSingleElement() const { 138 if (Upper == Lower + 1) 139 return &Lower; 140 return nullptr; 141 } 142 143 /// Return true if this set contains exactly one member. 144 /// 145 bool isSingleElement() const { return getSingleElement() != nullptr; } 146 147 /// Return the number of elements in this set. 148 /// 149 APInt getSetSize() const; 150 151 /// Return the largest unsigned value contained in the ConstantRange. 152 /// 153 APInt getUnsignedMax() const; 154 155 /// Return the smallest unsigned value contained in the ConstantRange. 156 /// 157 APInt getUnsignedMin() const; 158 159 /// Return the largest signed value contained in the ConstantRange. 160 /// 161 APInt getSignedMax() const; 162 163 /// Return the smallest signed value contained in the ConstantRange. 164 /// 165 APInt getSignedMin() const; 166 167 /// Return true if this range is equal to another range. 168 /// 169 bool operator==(const ConstantRange &CR) const { 170 return Lower == CR.Lower && Upper == CR.Upper; 171 } 172 bool operator!=(const ConstantRange &CR) const { 173 return !operator==(CR); 174 } 175 176 /// Subtract the specified constant from the endpoints of this constant range. 177 ConstantRange subtract(const APInt &CI) const; 178 179 /// \brief Subtract the specified range from this range (aka relative 180 /// complement of the sets). 181 ConstantRange difference(const ConstantRange &CR) const; 182 183 /// Return the range that results from the intersection of 184 /// this range with another range. The resultant range is guaranteed to 185 /// include all elements contained in both input ranges, and to have the 186 /// smallest possible set size that does so. Because there may be two 187 /// intersections with the same set size, A.intersectWith(B) might not 188 /// be equal to B.intersectWith(A). 189 /// 190 ConstantRange intersectWith(const ConstantRange &CR) const; 191 192 /// Return the range that results from the union of this range 193 /// with another range. The resultant range is guaranteed to include the 194 /// elements of both sets, but may contain more. For example, [3, 9) union 195 /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included 196 /// in either set before. 197 /// 198 ConstantRange unionWith(const ConstantRange &CR) const; 199 200 /// Return a new range in the specified integer type, which must 201 /// be strictly larger than the current type. The returned range will 202 /// correspond to the possible range of values if the source range had been 203 /// zero extended to BitWidth. 204 ConstantRange zeroExtend(uint32_t BitWidth) const; 205 206 /// Return a new range in the specified integer type, which must 207 /// be strictly larger than the current type. The returned range will 208 /// correspond to the possible range of values if the source range had been 209 /// sign extended to BitWidth. 210 ConstantRange signExtend(uint32_t BitWidth) const; 211 212 /// Return a new range in the specified integer type, which must be 213 /// strictly smaller than the current type. The returned range will 214 /// correspond to the possible range of values if the source range had been 215 /// truncated to the specified type. 216 ConstantRange truncate(uint32_t BitWidth) const; 217 218 /// Make this range have the bit width given by \p BitWidth. The 219 /// value is zero extended, truncated, or left alone to make it that width. 220 ConstantRange zextOrTrunc(uint32_t BitWidth) const; 221 222 /// Make this range have the bit width given by \p BitWidth. The 223 /// value is sign extended, truncated, or left alone to make it that width. 224 ConstantRange sextOrTrunc(uint32_t BitWidth) const; 225 226 /// Return a new range representing the possible values resulting 227 /// from an addition of a value in this range and a value in \p Other. 228 ConstantRange add(const ConstantRange &Other) const; 229 230 /// Return a new range representing the possible values resulting 231 /// from a subtraction of a value in this range and a value in \p Other. 232 ConstantRange sub(const ConstantRange &Other) const; 233 234 /// Return a new range representing the possible values resulting 235 /// from a multiplication of a value in this range and a value in \p Other, 236 /// treating both this and \p Other as unsigned ranges. 237 ConstantRange multiply(const ConstantRange &Other) const; 238 239 /// Return a new range representing the possible values resulting 240 /// from a signed maximum of a value in this range and a value in \p Other. 241 ConstantRange smax(const ConstantRange &Other) const; 242 243 /// Return a new range representing the possible values resulting 244 /// from an unsigned maximum of a value in this range and a value in \p Other. 245 ConstantRange umax(const ConstantRange &Other) const; 246 247 /// Return a new range representing the possible values resulting 248 /// from an unsigned division of a value in this range and a value in 249 /// \p Other. 250 ConstantRange udiv(const ConstantRange &Other) const; 251 252 /// Return a new range representing the possible values resulting 253 /// from a binary-and of a value in this range by a value in \p Other. 254 ConstantRange binaryAnd(const ConstantRange &Other) const; 255 256 /// Return a new range representing the possible values resulting 257 /// from a binary-or of a value in this range by a value in \p Other. 258 ConstantRange binaryOr(const ConstantRange &Other) const; 259 260 /// Return a new range representing the possible values resulting 261 /// from a left shift of a value in this range by a value in \p Other. 262 /// TODO: This isn't fully implemented yet. 263 ConstantRange shl(const ConstantRange &Other) const; 264 265 /// Return a new range representing the possible values resulting from a 266 /// logical right shift of a value in this range and a value in \p Other. 267 ConstantRange lshr(const ConstantRange &Other) const; 268 269 /// Return a new range that is the logical not of the current set. 270 /// 271 ConstantRange inverse() const; 272 273 /// Print out the bounds to a stream. 274 /// 275 void print(raw_ostream &OS) const; 276 277 /// Allow printing from a debugger easily. 278 /// 279 void dump() const; 280 }; 281 282 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) { 283 CR.print(OS); 284 return OS; 285 } 286 287 } // End llvm namespace 288 289 #endif 290
