1 //===- ConstantRange.h - Represent a range ----------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Represent a range of possible values that may occur when the program is run 10 // for an integral value. This keeps track of a lower and upper bound for the 11 // constant, which MAY wrap around the end of the numeric range. To do this, it 12 // keeps track of a [lower, upper) bound, which specifies an interval just like 13 // STL iterators. When used with boolean values, the following are important 14 // ranges: : 15 // 16 // [F, F) = {} = Empty set 17 // [T, F) = {T} 18 // [F, T) = {F} 19 // [T, T) = {F, T} = Full set 20 // 21 // The other integral ranges use min/max values for special range values. For 22 // example, for 8-bit types, it uses: 23 // [0, 0) = {} = Empty set 24 // [255, 255) = {0..255} = Full Set 25 // 26 // Note that ConstantRange can be used to represent either signed or 27 // unsigned ranges. 28 // 29 //===----------------------------------------------------------------------===// 30 31 #ifndef LLVM_IR_CONSTANTRANGE_H 32 #define LLVM_IR_CONSTANTRANGE_H 33 34 #include "llvm/ADT/APInt.h" 35 #include "llvm/IR/InstrTypes.h" 36 #include "llvm/IR/Instruction.h" 37 #include "llvm/Support/Compiler.h" 38 #include <cstdint> 39 40 namespace llvm { 41 42 class MDNode; 43 class raw_ostream; 44 struct KnownBits; 45 46 /// This class represents a range of values. 47 class [[nodiscard]] ConstantRange { 48 APInt Lower, Upper; 49 50 /// Create empty constant range with same bitwidth. getEmpty()51 ConstantRange getEmpty() const { 52 return ConstantRange(getBitWidth(), false); 53 } 54 55 /// Create full constant range with same bitwidth. getFull()56 ConstantRange getFull() const { 57 return ConstantRange(getBitWidth(), true); 58 } 59 60 public: 61 /// Initialize a full or empty set for the specified bit width. 62 explicit ConstantRange(uint32_t BitWidth, bool isFullSet); 63 64 /// Initialize a range to hold the single specified value. 65 ConstantRange(APInt Value); 66 67 /// Initialize a range of values explicitly. This will assert out if 68 /// Lower==Upper and Lower != Min or Max value for its type. It will also 69 /// assert out if the two APInt's are not the same bit width. 70 ConstantRange(APInt Lower, APInt Upper); 71 72 /// Create empty constant range with the given bit width. getEmpty(uint32_t BitWidth)73 static ConstantRange getEmpty(uint32_t BitWidth) { 74 return ConstantRange(BitWidth, false); 75 } 76 77 /// Create full constant range with the given bit width. getFull(uint32_t BitWidth)78 static ConstantRange getFull(uint32_t BitWidth) { 79 return ConstantRange(BitWidth, true); 80 } 81 82 /// Create non-empty constant range with the given bounds. If Lower and 83 /// Upper are the same, a full range is returned. getNonEmpty(APInt Lower,APInt Upper)84 static ConstantRange getNonEmpty(APInt Lower, APInt Upper) { 85 if (Lower == Upper) 86 return getFull(Lower.getBitWidth()); 87 return ConstantRange(std::move(Lower), std::move(Upper)); 88 } 89 90 /// Initialize a range based on a known bits constraint. The IsSigned flag 91 /// indicates whether the constant range should not wrap in the signed or 92 /// unsigned domain. 93 static ConstantRange fromKnownBits(const KnownBits &Known, bool IsSigned); 94 95 /// Produce the smallest range such that all values that may satisfy the given 96 /// predicate with any value contained within Other is contained in the 97 /// returned range. Formally, this returns a superset of 98 /// 'union over all y in Other . { x : icmp op x y is true }'. If the exact 99 /// answer is not representable as a ConstantRange, the return value will be a 100 /// proper superset of the above. 101 /// 102 /// Example: Pred = ult and Other = i8 [2, 5) returns Result = [0, 4) 103 static ConstantRange makeAllowedICmpRegion(CmpInst::Predicate Pred, 104 const ConstantRange &Other); 105 106 /// Produce the largest range such that all values in the returned range 107 /// satisfy the given predicate with all values contained within Other. 108 /// Formally, this returns a subset of 109 /// 'intersection over all y in Other . { x : icmp op x y is true }'. If the 110 /// exact answer is not representable as a ConstantRange, the return value 111 /// will be a proper subset of the above. 112 /// 113 /// Example: Pred = ult and Other = i8 [2, 5) returns [0, 2) 114 static ConstantRange makeSatisfyingICmpRegion(CmpInst::Predicate Pred, 115 const ConstantRange &Other); 116 117 /// Produce the exact range such that all values in the returned range satisfy 118 /// the given predicate with any value contained within Other. Formally, this 119 /// returns the exact answer when the superset of 'union over all y in Other 120 /// is exactly same as the subset of intersection over all y in Other. 121 /// { x : icmp op x y is true}'. 122 /// 123 /// Example: Pred = ult and Other = i8 3 returns [0, 3) 124 static ConstantRange makeExactICmpRegion(CmpInst::Predicate Pred, 125 const APInt &Other); 126 127 /// Does the predicate \p Pred hold between ranges this and \p Other? 128 /// NOTE: false does not mean that inverse predicate holds! 129 bool icmp(CmpInst::Predicate Pred, const ConstantRange &Other) const; 130 131 /// Return true iff CR1 ult CR2 is equivalent to CR1 slt CR2. 132 /// Does not depend on strictness/direction of the predicate. 133 static bool 134 areInsensitiveToSignednessOfICmpPredicate(const ConstantRange &CR1, 135 const ConstantRange &CR2); 136 137 /// Return true iff CR1 ult CR2 is equivalent to CR1 sge CR2. 138 /// Does not depend on strictness/direction of the predicate. 139 static bool 140 areInsensitiveToSignednessOfInvertedICmpPredicate(const ConstantRange &CR1, 141 const ConstantRange &CR2); 142 143 /// If the comparison between constant ranges this and Other 144 /// is insensitive to the signedness of the comparison predicate, 145 /// return a predicate equivalent to \p Pred, with flipped signedness 146 /// (i.e. unsigned instead of signed or vice versa), and maybe inverted, 147 /// otherwise returns CmpInst::Predicate::BAD_ICMP_PREDICATE. 148 static CmpInst::Predicate 149 getEquivalentPredWithFlippedSignedness(CmpInst::Predicate Pred, 150 const ConstantRange &CR1, 151 const ConstantRange &CR2); 152 153 /// Produce the largest range containing all X such that "X BinOp Y" is 154 /// guaranteed not to wrap (overflow) for *all* Y in Other. However, there may 155 /// be *some* Y in Other for which additional X not contained in the result 156 /// also do not overflow. 157 /// 158 /// NoWrapKind must be one of OBO::NoUnsignedWrap or OBO::NoSignedWrap. 159 /// 160 /// Examples: 161 /// typedef OverflowingBinaryOperator OBO; 162 /// #define MGNR makeGuaranteedNoWrapRegion 163 /// MGNR(Add, [i8 1, 2), OBO::NoSignedWrap) == [-128, 127) 164 /// MGNR(Add, [i8 1, 2), OBO::NoUnsignedWrap) == [0, -1) 165 /// MGNR(Add, [i8 0, 1), OBO::NoUnsignedWrap) == Full Set 166 /// MGNR(Add, [i8 -1, 6), OBO::NoSignedWrap) == [INT_MIN+1, INT_MAX-4) 167 /// MGNR(Sub, [i8 1, 2), OBO::NoSignedWrap) == [-127, 128) 168 /// MGNR(Sub, [i8 1, 2), OBO::NoUnsignedWrap) == [1, 0) 169 static ConstantRange makeGuaranteedNoWrapRegion(Instruction::BinaryOps BinOp, 170 const ConstantRange &Other, 171 unsigned NoWrapKind); 172 173 /// Produce the range that contains X if and only if "X BinOp Other" does 174 /// not wrap. 175 static ConstantRange makeExactNoWrapRegion(Instruction::BinaryOps BinOp, 176 const APInt &Other, 177 unsigned NoWrapKind); 178 179 /// Initialize a range containing all values X that satisfy `(X & Mask) 180 /// != C`. Note that the range returned may contain values where `(X & Mask) 181 /// == C` holds, making it less precise, but still conservative. 182 static ConstantRange makeMaskNotEqualRange(const APInt &Mask, const APInt &C); 183 184 /// Returns true if ConstantRange calculations are supported for intrinsic 185 /// with \p IntrinsicID. 186 static bool isIntrinsicSupported(Intrinsic::ID IntrinsicID); 187 188 /// Compute range of intrinsic result for the given operand ranges. 189 static ConstantRange intrinsic(Intrinsic::ID IntrinsicID, 190 ArrayRef<ConstantRange> Ops); 191 192 /// Set up \p Pred and \p RHS such that 193 /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this. Return true if 194 /// successful. 195 bool getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS) const; 196 197 /// Set up \p Pred, \p RHS and \p Offset such that (V + Offset) Pred RHS 198 /// is true iff V is in the range. Prefers using Offset == 0 if possible. 199 void 200 getEquivalentICmp(CmpInst::Predicate &Pred, APInt &RHS, APInt &Offset) const; 201 202 /// Return the lower value for this range. getLower()203 const APInt &getLower() const { return Lower; } 204 205 /// Return the upper value for this range. getUpper()206 const APInt &getUpper() const { return Upper; } 207 208 /// Get the bit width of this ConstantRange. getBitWidth()209 uint32_t getBitWidth() const { return Lower.getBitWidth(); } 210 211 /// Return true if this set contains all of the elements possible 212 /// for this data-type. 213 bool isFullSet() const; 214 215 /// Return true if this set contains no members. 216 bool isEmptySet() const; 217 218 /// Return true if this set wraps around the unsigned domain. Special cases: 219 /// * Empty set: Not wrapped. 220 /// * Full set: Not wrapped. 221 /// * [X, 0) == [X, Max]: Not wrapped. 222 bool isWrappedSet() const; 223 224 /// Return true if the exclusive upper bound wraps around the unsigned 225 /// domain. Special cases: 226 /// * Empty set: Not wrapped. 227 /// * Full set: Not wrapped. 228 /// * [X, 0): Wrapped. 229 bool isUpperWrapped() const; 230 231 /// Return true if this set wraps around the signed domain. Special cases: 232 /// * Empty set: Not wrapped. 233 /// * Full set: Not wrapped. 234 /// * [X, SignedMin) == [X, SignedMax]: Not wrapped. 235 bool isSignWrappedSet() const; 236 237 /// Return true if the (exclusive) upper bound wraps around the signed 238 /// domain. Special cases: 239 /// * Empty set: Not wrapped. 240 /// * Full set: Not wrapped. 241 /// * [X, SignedMin): Wrapped. 242 bool isUpperSignWrapped() const; 243 244 /// Return true if the specified value is in the set. 245 bool contains(const APInt &Val) const; 246 247 /// Return true if the other range is a subset of this one. 248 bool contains(const ConstantRange &CR) const; 249 250 /// If this set contains a single element, return it, otherwise return null. getSingleElement()251 const APInt *getSingleElement() const { 252 if (Upper == Lower + 1) 253 return &Lower; 254 return nullptr; 255 } 256 257 /// If this set contains all but a single element, return it, otherwise return 258 /// null. getSingleMissingElement()259 const APInt *getSingleMissingElement() const { 260 if (Lower == Upper + 1) 261 return &Upper; 262 return nullptr; 263 } 264 265 /// Return true if this set contains exactly one member. isSingleElement()266 bool isSingleElement() const { return getSingleElement() != nullptr; } 267 268 /// Compare set size of this range with the range CR. 269 bool isSizeStrictlySmallerThan(const ConstantRange &CR) const; 270 271 /// Compare set size of this range with Value. 272 bool isSizeLargerThan(uint64_t MaxSize) const; 273 274 /// Return true if all values in this range are negative. 275 bool isAllNegative() const; 276 277 /// Return true if all values in this range are non-negative. 278 bool isAllNonNegative() const; 279 280 /// Return true if all values in this range are positive. 281 bool isAllPositive() const; 282 283 /// Return the largest unsigned value contained in the ConstantRange. 284 APInt getUnsignedMax() const; 285 286 /// Return the smallest unsigned value contained in the ConstantRange. 287 APInt getUnsignedMin() const; 288 289 /// Return the largest signed value contained in the ConstantRange. 290 APInt getSignedMax() const; 291 292 /// Return the smallest signed value contained in the ConstantRange. 293 APInt getSignedMin() const; 294 295 /// Return true if this range is equal to another range. 296 bool operator==(const ConstantRange &CR) const { 297 return Lower == CR.Lower && Upper == CR.Upper; 298 } 299 bool operator!=(const ConstantRange &CR) const { 300 return !operator==(CR); 301 } 302 303 /// Compute the maximal number of active bits needed to represent every value 304 /// in this range. 305 unsigned getActiveBits() const; 306 307 /// Compute the maximal number of bits needed to represent every value 308 /// in this signed range. 309 unsigned getMinSignedBits() const; 310 311 /// Subtract the specified constant from the endpoints of this constant range. 312 ConstantRange subtract(const APInt &CI) const; 313 314 /// Subtract the specified range from this range (aka relative complement of 315 /// the sets). 316 ConstantRange difference(const ConstantRange &CR) const; 317 318 /// If represented precisely, the result of some range operations may consist 319 /// of multiple disjoint ranges. As only a single range may be returned, any 320 /// range covering these disjoint ranges constitutes a valid result, but some 321 /// may be more useful than others depending on context. The preferred range 322 /// type specifies whether a range that is non-wrapping in the unsigned or 323 /// signed domain, or has the smallest size, is preferred. If a signedness is 324 /// preferred but all ranges are non-wrapping or all wrapping, then the 325 /// smallest set size is preferred. If there are multiple smallest sets, any 326 /// one of them may be returned. 327 enum PreferredRangeType { Smallest, Unsigned, Signed }; 328 329 /// Return the range that results from the intersection of this range with 330 /// another range. If the intersection is disjoint, such that two results 331 /// are possible, the preferred range is determined by the PreferredRangeType. 332 ConstantRange intersectWith(const ConstantRange &CR, 333 PreferredRangeType Type = Smallest) const; 334 335 /// Return the range that results from the union of this range 336 /// with another range. The resultant range is guaranteed to include the 337 /// elements of both sets, but may contain more. For example, [3, 9) union 338 /// [12,15) is [3, 15), which includes 9, 10, and 11, which were not included 339 /// in either set before. 340 ConstantRange unionWith(const ConstantRange &CR, 341 PreferredRangeType Type = Smallest) const; 342 343 /// Intersect the two ranges and return the result if it can be represented 344 /// exactly, otherwise return std::nullopt. 345 std::optional<ConstantRange> 346 exactIntersectWith(const ConstantRange &CR) const; 347 348 /// Union the two ranges and return the result if it can be represented 349 /// exactly, otherwise return std::nullopt. 350 std::optional<ConstantRange> exactUnionWith(const ConstantRange &CR) const; 351 352 /// Return a new range representing the possible values resulting 353 /// from an application of the specified cast operator to this range. \p 354 /// BitWidth is the target bitwidth of the cast. For casts which don't 355 /// change bitwidth, it must be the same as the source bitwidth. For casts 356 /// which do change bitwidth, the bitwidth must be consistent with the 357 /// requested cast and source bitwidth. 358 ConstantRange castOp(Instruction::CastOps CastOp, 359 uint32_t BitWidth) const; 360 361 /// Return a new range in the specified integer type, which must 362 /// be strictly larger than the current type. The returned range will 363 /// correspond to the possible range of values if the source range had been 364 /// zero extended to BitWidth. 365 ConstantRange zeroExtend(uint32_t BitWidth) const; 366 367 /// Return a new range in the specified integer type, which must 368 /// be strictly larger than the current type. The returned range will 369 /// correspond to the possible range of values if the source range had been 370 /// sign extended to BitWidth. 371 ConstantRange signExtend(uint32_t BitWidth) const; 372 373 /// Return a new range in the specified integer type, which must be 374 /// strictly smaller than the current type. The returned range will 375 /// correspond to the possible range of values if the source range had been 376 /// truncated to the specified type. 377 ConstantRange truncate(uint32_t BitWidth) const; 378 379 /// Make this range have the bit width given by \p BitWidth. The 380 /// value is zero extended, truncated, or left alone to make it that width. 381 ConstantRange zextOrTrunc(uint32_t BitWidth) const; 382 383 /// Make this range have the bit width given by \p BitWidth. The 384 /// value is sign extended, truncated, or left alone to make it that width. 385 ConstantRange sextOrTrunc(uint32_t BitWidth) const; 386 387 /// Return a new range representing the possible values resulting 388 /// from an application of the specified binary operator to an left hand side 389 /// of this range and a right hand side of \p Other. 390 ConstantRange binaryOp(Instruction::BinaryOps BinOp, 391 const ConstantRange &Other) const; 392 393 /// Return a new range representing the possible values resulting 394 /// from an application of the specified overflowing binary operator to a 395 /// left hand side of this range and a right hand side of \p Other given 396 /// the provided knowledge about lack of wrapping \p NoWrapKind. 397 ConstantRange overflowingBinaryOp(Instruction::BinaryOps BinOp, 398 const ConstantRange &Other, 399 unsigned NoWrapKind) const; 400 401 /// Return a new range representing the possible values resulting 402 /// from an addition of a value in this range and a value in \p Other. 403 ConstantRange add(const ConstantRange &Other) const; 404 405 /// Return a new range representing the possible values resulting 406 /// from an addition with wrap type \p NoWrapKind of a value in this 407 /// range and a value in \p Other. 408 /// If the result range is disjoint, the preferred range is determined by the 409 /// \p PreferredRangeType. 410 ConstantRange addWithNoWrap(const ConstantRange &Other, unsigned NoWrapKind, 411 PreferredRangeType RangeType = Smallest) const; 412 413 /// Return a new range representing the possible values resulting 414 /// from a subtraction of a value in this range and a value in \p Other. 415 ConstantRange sub(const ConstantRange &Other) const; 416 417 /// Return a new range representing the possible values resulting 418 /// from an subtraction with wrap type \p NoWrapKind of a value in this 419 /// range and a value in \p Other. 420 /// If the result range is disjoint, the preferred range is determined by the 421 /// \p PreferredRangeType. 422 ConstantRange subWithNoWrap(const ConstantRange &Other, unsigned NoWrapKind, 423 PreferredRangeType RangeType = Smallest) const; 424 425 /// Return a new range representing the possible values resulting 426 /// from a multiplication of a value in this range and a value in \p Other, 427 /// treating both this and \p Other as unsigned ranges. 428 ConstantRange multiply(const ConstantRange &Other) const; 429 430 /// Return a new range representing the possible values resulting 431 /// from a multiplication with wrap type \p NoWrapKind of a value in this 432 /// range and a value in \p Other. 433 /// If the result range is disjoint, the preferred range is determined by the 434 /// \p PreferredRangeType. 435 ConstantRange 436 multiplyWithNoWrap(const ConstantRange &Other, unsigned NoWrapKind, 437 PreferredRangeType RangeType = Smallest) const; 438 439 /// Return range of possible values for a signed multiplication of this and 440 /// \p Other. However, if overflow is possible always return a full range 441 /// rather than trying to determine a more precise result. 442 ConstantRange smul_fast(const ConstantRange &Other) const; 443 444 /// Return a new range representing the possible values resulting 445 /// from a signed maximum of a value in this range and a value in \p Other. 446 ConstantRange smax(const ConstantRange &Other) const; 447 448 /// Return a new range representing the possible values resulting 449 /// from an unsigned maximum of a value in this range and a value in \p Other. 450 ConstantRange umax(const ConstantRange &Other) const; 451 452 /// Return a new range representing the possible values resulting 453 /// from a signed minimum of a value in this range and a value in \p Other. 454 ConstantRange smin(const ConstantRange &Other) const; 455 456 /// Return a new range representing the possible values resulting 457 /// from an unsigned minimum of a value in this range and a value in \p Other. 458 ConstantRange umin(const ConstantRange &Other) const; 459 460 /// Return a new range representing the possible values resulting 461 /// from an unsigned division of a value in this range and a value in 462 /// \p Other. 463 ConstantRange udiv(const ConstantRange &Other) const; 464 465 /// Return a new range representing the possible values resulting 466 /// from a signed division of a value in this range and a value in 467 /// \p Other. Division by zero and division of SignedMin by -1 are considered 468 /// undefined behavior, in line with IR, and do not contribute towards the 469 /// result. 470 ConstantRange sdiv(const ConstantRange &Other) const; 471 472 /// Return a new range representing the possible values resulting 473 /// from an unsigned remainder operation of a value in this range and a 474 /// value in \p Other. 475 ConstantRange urem(const ConstantRange &Other) const; 476 477 /// Return a new range representing the possible values resulting 478 /// from a signed remainder operation of a value in this range and a 479 /// value in \p Other. 480 ConstantRange srem(const ConstantRange &Other) const; 481 482 /// Return a new range representing the possible values resulting from 483 /// a binary-xor of a value in this range by an all-one value, 484 /// aka bitwise complement operation. 485 ConstantRange binaryNot() const; 486 487 /// Return a new range representing the possible values resulting 488 /// from a binary-and of a value in this range by a value in \p Other. 489 ConstantRange binaryAnd(const ConstantRange &Other) const; 490 491 /// Return a new range representing the possible values resulting 492 /// from a binary-or of a value in this range by a value in \p Other. 493 ConstantRange binaryOr(const ConstantRange &Other) const; 494 495 /// Return a new range representing the possible values resulting 496 /// from a binary-xor of a value in this range by a value in \p Other. 497 ConstantRange binaryXor(const ConstantRange &Other) const; 498 499 /// Return a new range representing the possible values resulting 500 /// from a left shift of a value in this range by a value in \p Other. 501 /// TODO: This isn't fully implemented yet. 502 ConstantRange shl(const ConstantRange &Other) const; 503 504 /// Return a new range representing the possible values resulting from a 505 /// logical right shift of a value in this range and a value in \p Other. 506 ConstantRange lshr(const ConstantRange &Other) const; 507 508 /// Return a new range representing the possible values resulting from a 509 /// arithmetic right shift of a value in this range and a value in \p Other. 510 ConstantRange ashr(const ConstantRange &Other) const; 511 512 /// Perform an unsigned saturating addition of two constant ranges. 513 ConstantRange uadd_sat(const ConstantRange &Other) const; 514 515 /// Perform a signed saturating addition of two constant ranges. 516 ConstantRange sadd_sat(const ConstantRange &Other) const; 517 518 /// Perform an unsigned saturating subtraction of two constant ranges. 519 ConstantRange usub_sat(const ConstantRange &Other) const; 520 521 /// Perform a signed saturating subtraction of two constant ranges. 522 ConstantRange ssub_sat(const ConstantRange &Other) const; 523 524 /// Perform an unsigned saturating multiplication of two constant ranges. 525 ConstantRange umul_sat(const ConstantRange &Other) const; 526 527 /// Perform a signed saturating multiplication of two constant ranges. 528 ConstantRange smul_sat(const ConstantRange &Other) const; 529 530 /// Perform an unsigned saturating left shift of this constant range by a 531 /// value in \p Other. 532 ConstantRange ushl_sat(const ConstantRange &Other) const; 533 534 /// Perform a signed saturating left shift of this constant range by a 535 /// value in \p Other. 536 ConstantRange sshl_sat(const ConstantRange &Other) const; 537 538 /// Return a new range that is the logical not of the current set. 539 ConstantRange inverse() const; 540 541 /// Calculate absolute value range. If the original range contains signed 542 /// min, then the resulting range will contain signed min if and only if 543 /// \p IntMinIsPoison is false. 544 ConstantRange abs(bool IntMinIsPoison = false) const; 545 546 /// Calculate ctlz range. If \p ZeroIsPoison is set, the range is computed 547 /// ignoring a possible zero value contained in the input range. 548 ConstantRange ctlz(bool ZeroIsPoison = false) const; 549 550 /// Calculate cttz range. If \p ZeroIsPoison is set, the range is computed 551 /// ignoring a possible zero value contained in the input range. 552 ConstantRange cttz(bool ZeroIsPoison = false) const; 553 554 /// Calculate ctpop range. 555 ConstantRange ctpop() const; 556 557 /// Represents whether an operation on the given constant range is known to 558 /// always or never overflow. 559 enum class OverflowResult { 560 /// Always overflows in the direction of signed/unsigned min value. 561 AlwaysOverflowsLow, 562 /// Always overflows in the direction of signed/unsigned max value. 563 AlwaysOverflowsHigh, 564 /// May or may not overflow. 565 MayOverflow, 566 /// Never overflows. 567 NeverOverflows, 568 }; 569 570 /// Return whether unsigned add of the two ranges always/never overflows. 571 OverflowResult unsignedAddMayOverflow(const ConstantRange &Other) const; 572 573 /// Return whether signed add of the two ranges always/never overflows. 574 OverflowResult signedAddMayOverflow(const ConstantRange &Other) const; 575 576 /// Return whether unsigned sub of the two ranges always/never overflows. 577 OverflowResult unsignedSubMayOverflow(const ConstantRange &Other) const; 578 579 /// Return whether signed sub of the two ranges always/never overflows. 580 OverflowResult signedSubMayOverflow(const ConstantRange &Other) const; 581 582 /// Return whether unsigned mul of the two ranges always/never overflows. 583 OverflowResult unsignedMulMayOverflow(const ConstantRange &Other) const; 584 585 /// Return known bits for values in this range. 586 KnownBits toKnownBits() const; 587 588 /// Print out the bounds to a stream. 589 void print(raw_ostream &OS) const; 590 591 /// Allow printing from a debugger easily. 592 void dump() const; 593 }; 594 595 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantRange &CR) { 596 CR.print(OS); 597 return OS; 598 } 599 600 /// Parse out a conservative ConstantRange from !range metadata. 601 /// 602 /// E.g. if RangeMD is !{i32 0, i32 10, i32 15, i32 20} then return [0, 20). 603 ConstantRange getConstantRangeFromMetadata(const MDNode &RangeMD); 604 605 } // end namespace llvm 606 607 #endif // LLVM_IR_CONSTANTRANGE_H 608