include/llvm/IR/Operator.h

   1 //===-- llvm/Operator.h - Operator utility subclass -------------*- 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 // This file defines various classes for working with Instructions and
  10 // ConstantExprs.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_IR_OPERATOR_H
  15 #define LLVM_IR_OPERATOR_H
  16
  17 #include "llvm/ADT/None.h"
  18 #include "llvm/ADT/Optional.h"
  19 #include "llvm/IR/Constants.h"
  20 #include "llvm/IR/Instruction.h"
  21 #include "llvm/IR/Type.h"
  22 #include "llvm/IR/Value.h"
  23 #include "llvm/Support/Casting.h"
  24 #include <cstddef>
  25
  26 namespace llvm {
  27
  28 /// This is a utility class that provides an abstraction for the common
  29 /// functionality between Instructions and ConstantExprs.
  30 class Operator : public User {
  31 public:
  32   // The Operator class is intended to be used as a utility, and is never itself
  33   // instantiated.
  34   Operator() = delete;
  35   ~Operator() = delete;
  36
  37   void *operator new(size_t s) = delete;
  38
  39   /// Return the opcode for this Instruction or ConstantExpr.
  40   unsigned getOpcode() const {
  41     if (const Instruction *I = dyn_cast<Instruction>(this))
  42       return I->getOpcode();
  43     return cast<ConstantExpr>(this)->getOpcode();
  44   }
  45
  46   /// If V is an Instruction or ConstantExpr, return its opcode.
  47   /// Otherwise return UserOp1.
  48   static unsigned getOpcode(const Value *V) {
  49     if (const Instruction *I = dyn_cast<Instruction>(V))
  50       return I->getOpcode();
  51     if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
  52       return CE->getOpcode();
  53     return Instruction::UserOp1;
  54   }
  55
  56   static bool classof(const Instruction *) { return true; }
  57   static bool classof(const ConstantExpr *) { return true; }
  58   static bool classof(const Value *V) {
  59     return isa<Instruction>(V) || isa<ConstantExpr>(V);
  60   }
  61 };
  62
  63 /// Utility class for integer operators which may exhibit overflow - Add, Sub,
  64 /// Mul, and Shl. It does not include SDiv, despite that operator having the
  65 /// potential for overflow.
  66 class OverflowingBinaryOperator : public Operator {
  67 public:
  68   enum {
  69     NoUnsignedWrap = (1 << 0),
  70     NoSignedWrap   = (1 << 1)
  71   };
  72
  73 private:
  74   friend class Instruction;
  75   friend class ConstantExpr;
  76
  77   void setHasNoUnsignedWrap(bool B) {
  78     SubclassOptionalData =
  79       (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap);
  80   }
  81   void setHasNoSignedWrap(bool B) {
  82     SubclassOptionalData =
  83       (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap);
  84   }
  85
  86 public:
  87   /// Test whether this operation is known to never
  88   /// undergo unsigned overflow, aka the nuw property.
  89   bool hasNoUnsignedWrap() const {
  90     return SubclassOptionalData & NoUnsignedWrap;
  91   }
  92
  93   /// Test whether this operation is known to never
  94   /// undergo signed overflow, aka the nsw property.
  95   bool hasNoSignedWrap() const {
  96     return (SubclassOptionalData & NoSignedWrap) != 0;
  97   }
  98
  99   static bool classof(const Instruction *I) {
 100     return I->getOpcode() == Instruction::Add ||
 101            I->getOpcode() == Instruction::Sub ||
 102            I->getOpcode() == Instruction::Mul ||
 103            I->getOpcode() == Instruction::Shl;
 104   }
 105   static bool classof(const ConstantExpr *CE) {
 106     return CE->getOpcode() == Instruction::Add ||
 107            CE->getOpcode() == Instruction::Sub ||
 108            CE->getOpcode() == Instruction::Mul ||
 109            CE->getOpcode() == Instruction::Shl;
 110   }
 111   static bool classof(const Value *V) {
 112     return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
 113            (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
 114   }
 115 };
 116
 117 /// A udiv or sdiv instruction, which can be marked as "exact",
 118 /// indicating that no bits are destroyed.
 119 class PossiblyExactOperator : public Operator {
 120 public:
 121   enum {
 122     IsExact = (1 << 0)
 123   };
 124
 125 private:
 126   friend class Instruction;
 127   friend class ConstantExpr;
 128
 129   void setIsExact(bool B) {
 130     SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact);
 131   }
 132
 133 public:
 134   /// Test whether this division is known to be exact, with zero remainder.
 135   bool isExact() const {
 136     return SubclassOptionalData & IsExact;
 137   }
 138
 139   static bool isPossiblyExactOpcode(unsigned OpC) {
 140     return OpC == Instruction::SDiv ||
 141            OpC == Instruction::UDiv ||
 142            OpC == Instruction::AShr ||
 143            OpC == Instruction::LShr;
 144   }
 145
 146   static bool classof(const ConstantExpr *CE) {
 147     return isPossiblyExactOpcode(CE->getOpcode());
 148   }
 149   static bool classof(const Instruction *I) {
 150     return isPossiblyExactOpcode(I->getOpcode());
 151   }
 152   static bool classof(const Value *V) {
 153     return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
 154            (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
 155   }
 156 };
 157
 158 /// Convenience struct for specifying and reasoning about fast-math flags.
 159 class FastMathFlags {
 160 private:
 161   friend class FPMathOperator;
 162
 163   unsigned Flags = 0;
 164
 165   FastMathFlags(unsigned F) {
 166     // If all 7 bits are set, turn this into -1. If the number of bits grows,
 167     // this must be updated. This is intended to provide some forward binary
 168     // compatibility insurance for the meaning of 'fast' in case bits are added.
 169     if (F == 0x7F) Flags = ~0U;
 170     else Flags = F;
 171   }
 172
 173 public:
 174   // This is how the bits are used in Value::SubclassOptionalData so they
 175   // should fit there too.
 176   // WARNING: We're out of space. SubclassOptionalData only has 7 bits. New
 177   // functionality will require a change in how this information is stored.
 178   enum {
 179     AllowReassoc    = (1 << 0),
 180     NoNaNs          = (1 << 1),
 181     NoInfs          = (1 << 2),
 182     NoSignedZeros   = (1 << 3),
 183     AllowReciprocal = (1 << 4),
 184     AllowContract   = (1 << 5),
 185     ApproxFunc      = (1 << 6)
 186   };
 187
 188   FastMathFlags() = default;
 189
 190   static FastMathFlags getFast() {
 191     FastMathFlags FMF;
 192     FMF.setFast();
 193     return FMF;
 194   }
 195
 196   bool any() const { return Flags != 0; }
 197   bool none() const { return Flags == 0; }
 198   bool all() const { return Flags == ~0U; }
 199
 200   void clear() { Flags = 0; }
 201   void set()   { Flags = ~0U; }
 202
 203   /// Flag queries
 204   bool allowReassoc() const    { return 0 != (Flags & AllowReassoc); }
 205   bool noNaNs() const          { return 0 != (Flags & NoNaNs); }
 206   bool noInfs() const          { return 0 != (Flags & NoInfs); }
 207   bool noSignedZeros() const   { return 0 != (Flags & NoSignedZeros); }
 208   bool allowReciprocal() const { return 0 != (Flags & AllowReciprocal); }
 209   bool allowContract() const   { return 0 != (Flags & AllowContract); }
 210   bool approxFunc() const      { return 0 != (Flags & ApproxFunc); }
 211   /// 'Fast' means all bits are set.
 212   bool isFast() const          { return all(); }
 213
 214   /// Flag setters
 215   void setAllowReassoc(bool B = true) {
 216     Flags = (Flags & ~AllowReassoc) | B * AllowReassoc;
 217   }
 218   void setNoNaNs(bool B = true) {
 219     Flags = (Flags & ~NoNaNs) | B * NoNaNs;
 220   }
 221   void setNoInfs(bool B = true) {
 222     Flags = (Flags & ~NoInfs) | B * NoInfs;
 223   }
 224   void setNoSignedZeros(bool B = true) {
 225     Flags = (Flags & ~NoSignedZeros) | B * NoSignedZeros;
 226   }
 227   void setAllowReciprocal(bool B = true) {
 228     Flags = (Flags & ~AllowReciprocal) | B * AllowReciprocal;
 229   }
 230   void setAllowContract(bool B = true) {
 231     Flags = (Flags & ~AllowContract) | B * AllowContract;
 232   }
 233   void setApproxFunc(bool B = true) {
 234     Flags = (Flags & ~ApproxFunc) | B * ApproxFunc;
 235   }
 236   void setFast(bool B = true) { B ? set() : clear(); }
 237
 238   void operator&=(const FastMathFlags &OtherFlags) {
 239     Flags &= OtherFlags.Flags;
 240   }
 241 };
 242
 243 /// Utility class for floating point operations which can have
 244 /// information about relaxed accuracy requirements attached to them.
 245 class FPMathOperator : public Operator {
 246 private:
 247   friend class Instruction;
 248
 249   /// 'Fast' means all bits are set.
 250   void setFast(bool B) {
 251     setHasAllowReassoc(B);
 252     setHasNoNaNs(B);
 253     setHasNoInfs(B);
 254     setHasNoSignedZeros(B);
 255     setHasAllowReciprocal(B);
 256     setHasAllowContract(B);
 257     setHasApproxFunc(B);
 258   }
 259
 260   void setHasAllowReassoc(bool B) {
 261     SubclassOptionalData =
 262     (SubclassOptionalData & ~FastMathFlags::AllowReassoc) |
 263     (B * FastMathFlags::AllowReassoc);
 264   }
 265
 266   void setHasNoNaNs(bool B) {
 267     SubclassOptionalData =
 268       (SubclassOptionalData & ~FastMathFlags::NoNaNs) |
 269       (B * FastMathFlags::NoNaNs);
 270   }
 271
 272   void setHasNoInfs(bool B) {
 273     SubclassOptionalData =
 274       (SubclassOptionalData & ~FastMathFlags::NoInfs) |
 275       (B * FastMathFlags::NoInfs);
 276   }
 277
 278   void setHasNoSignedZeros(bool B) {
 279     SubclassOptionalData =
 280       (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) |
 281       (B * FastMathFlags::NoSignedZeros);
 282   }
 283
 284   void setHasAllowReciprocal(bool B) {
 285     SubclassOptionalData =
 286       (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) |
 287       (B * FastMathFlags::AllowReciprocal);
 288   }
 289
 290   void setHasAllowContract(bool B) {
 291     SubclassOptionalData =
 292         (SubclassOptionalData & ~FastMathFlags::AllowContract) |
 293         (B * FastMathFlags::AllowContract);
 294   }
 295
 296   void setHasApproxFunc(bool B) {
 297     SubclassOptionalData =
 298         (SubclassOptionalData & ~FastMathFlags::ApproxFunc) |
 299         (B * FastMathFlags::ApproxFunc);
 300   }
 301
 302   /// Convenience function for setting multiple fast-math flags.
 303   /// FMF is a mask of the bits to set.
 304   void setFastMathFlags(FastMathFlags FMF) {
 305     SubclassOptionalData |= FMF.Flags;
 306   }
 307
 308   /// Convenience function for copying all fast-math flags.
 309   /// All values in FMF are transferred to this operator.
 310   void copyFastMathFlags(FastMathFlags FMF) {
 311     SubclassOptionalData = FMF.Flags;
 312   }
 313
 314 public:
 315   /// Test if this operation allows all non-strict floating-point transforms.
 316   bool isFast() const {
 317     return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 &&
 318             (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 &&
 319             (SubclassOptionalData & FastMathFlags::NoInfs) != 0 &&
 320             (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 &&
 321             (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 &&
 322             (SubclassOptionalData & FastMathFlags::AllowContract) != 0 &&
 323             (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0);
 324   }
 325
 326   /// Test if this operation may be simplified with reassociative transforms.
 327   bool hasAllowReassoc() const {
 328     return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0;
 329   }
 330
 331   /// Test if this operation's arguments and results are assumed not-NaN.
 332   bool hasNoNaNs() const {
 333     return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0;
 334   }
 335
 336   /// Test if this operation's arguments and results are assumed not-infinite.
 337   bool hasNoInfs() const {
 338     return (SubclassOptionalData & FastMathFlags::NoInfs) != 0;
 339   }
 340
 341   /// Test if this operation can ignore the sign of zero.
 342   bool hasNoSignedZeros() const {
 343     return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0;
 344   }
 345
 346   /// Test if this operation can use reciprocal multiply instead of division.
 347   bool hasAllowReciprocal() const {
 348     return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0;
 349   }
 350
 351   /// Test if this operation can be floating-point contracted (FMA).
 352   bool hasAllowContract() const {
 353     return (SubclassOptionalData & FastMathFlags::AllowContract) != 0;
 354   }
 355
 356   /// Test if this operation allows approximations of math library functions or
 357   /// intrinsics.
 358   bool hasApproxFunc() const {
 359     return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0;
 360   }
 361
 362   /// Convenience function for getting all the fast-math flags
 363   FastMathFlags getFastMathFlags() const {
 364     return FastMathFlags(SubclassOptionalData);
 365   }
 366
 367   /// Get the maximum error permitted by this operation in ULPs. An accuracy of
 368   /// 0.0 means that the operation should be performed with the default
 369   /// precision.
 370   float getFPAccuracy() const;
 371
 372   static bool classof(const Value *V) {
 373     unsigned Opcode;
 374     if (auto *I = dyn_cast<Instruction>(V))
 375       Opcode = I->getOpcode();
 376     else if (auto *CE = dyn_cast<ConstantExpr>(V))
 377       Opcode = CE->getOpcode();
 378     else
 379       return false;
 380
 381     switch (Opcode) {
 382     case Instruction::FNeg:
 383     case Instruction::FAdd:
 384     case Instruction::FSub:
 385     case Instruction::FMul:
 386     case Instruction::FDiv:
 387     case Instruction::FRem:
 388     // FIXME: To clean up and correct the semantics of fast-math-flags, FCmp
 389     //        should not be treated as a math op, but the other opcodes should.
 390     //        This would make things consistent with Select/PHI (FP value type
 391     //        determines whether they are math ops and, therefore, capable of
 392     //        having fast-math-flags).
 393     case Instruction::FCmp:
 394       return true;
 395     case Instruction::PHI:
 396     case Instruction::Select:
 397     case Instruction::Call:
 398       return V->getType()->isFPOrFPVectorTy();
 399     default:
 400       return false;
 401     }
 402   }
 403 };
 404
 405 /// A helper template for defining operators for individual opcodes.
 406 template<typename SuperClass, unsigned Opc>
 407 class ConcreteOperator : public SuperClass {
 408 public:
 409   static bool classof(const Instruction *I) {
 410     return I->getOpcode() == Opc;
 411   }
 412   static bool classof(const ConstantExpr *CE) {
 413     return CE->getOpcode() == Opc;
 414   }
 415   static bool classof(const Value *V) {
 416     return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
 417            (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
 418   }
 419 };
 420
 421 class AddOperator
 422   : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> {
 423 };
 424 class SubOperator
 425   : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> {
 426 };
 427 class MulOperator
 428   : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> {
 429 };
 430 class ShlOperator
 431   : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> {
 432 };
 433
 434 class SDivOperator
 435   : public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> {
 436 };
 437 class UDivOperator
 438   : public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> {
 439 };
 440 class AShrOperator
 441   : public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> {
 442 };
 443 class LShrOperator
 444   : public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> {
 445 };
 446
 447 class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {};
 448
 449 class GEPOperator
 450   : public ConcreteOperator<Operator, Instruction::GetElementPtr> {
 451   friend class GetElementPtrInst;
 452   friend class ConstantExpr;
 453
 454   enum {
 455     IsInBounds = (1 << 0),
 456     // InRangeIndex: bits 1-6
 457   };
 458
 459   void setIsInBounds(bool B) {
 460     SubclassOptionalData =
 461       (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds);
 462   }
 463
 464 public:
 465   /// Test whether this is an inbounds GEP, as defined by LangRef.html.
 466   bool isInBounds() const {
 467     return SubclassOptionalData & IsInBounds;
 468   }
 469
 470   /// Returns the offset of the index with an inrange attachment, or None if
 471   /// none.
 472   Optional<unsigned> getInRangeIndex() const {
 473     if (SubclassOptionalData >> 1 == 0) return None;
 474     return (SubclassOptionalData >> 1) - 1;
 475   }
 476
 477   inline op_iterator       idx_begin()       { return op_begin()+1; }
 478   inline const_op_iterator idx_begin() const { return op_begin()+1; }
 479   inline op_iterator       idx_end()         { return op_end(); }
 480   inline const_op_iterator idx_end()   const { return op_end(); }
 481
 482   Value *getPointerOperand() {
 483     return getOperand(0);
 484   }
 485   const Value *getPointerOperand() const {
 486     return getOperand(0);
 487   }
 488   static unsigned getPointerOperandIndex() {
 489     return 0U;                      // get index for modifying correct operand
 490   }
 491
 492   /// Method to return the pointer operand as a PointerType.
 493   Type *getPointerOperandType() const {
 494     return getPointerOperand()->getType();
 495   }
 496
 497   Type *getSourceElementType() const;
 498   Type *getResultElementType() const;
 499
 500   /// Method to return the address space of the pointer operand.
 501   unsigned getPointerAddressSpace() const {
 502     return getPointerOperandType()->getPointerAddressSpace();
 503   }
 504
 505   unsigned getNumIndices() const {  // Note: always non-negative
 506     return getNumOperands() - 1;
 507   }
 508
 509   bool hasIndices() const {
 510     return getNumOperands() > 1;
 511   }
 512
 513   /// Return true if all of the indices of this GEP are zeros.
 514   /// If so, the result pointer and the first operand have the same
 515   /// value, just potentially different types.
 516   bool hasAllZeroIndices() const {
 517     for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
 518       if (ConstantInt *C = dyn_cast<ConstantInt>(I))
 519         if (C->isZero())
 520           continue;
 521       return false;
 522     }
 523     return true;
 524   }
 525
 526   /// Return true if all of the indices of this GEP are constant integers.
 527   /// If so, the result pointer and the first operand have
 528   /// a constant offset between them.
 529   bool hasAllConstantIndices() const {
 530     for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
 531       if (!isa<ConstantInt>(I))
 532         return false;
 533     }
 534     return true;
 535   }
 536
 537   unsigned countNonConstantIndices() const {
 538     return count_if(make_range(idx_begin(), idx_end()), [](const Use& use) {
 539         return !isa<ConstantInt>(*use);
 540       });
 541   }
 542
 543   /// Accumulate the constant address offset of this GEP if possible.
 544   ///
 545   /// This routine accepts an APInt into which it will accumulate the constant
 546   /// offset of this GEP if the GEP is in fact constant. If the GEP is not
 547   /// all-constant, it returns false and the value of the offset APInt is
 548   /// undefined (it is *not* preserved!). The APInt passed into this routine
 549   /// must be at exactly as wide as the IntPtr type for the address space of the
 550   /// base GEP pointer.
 551   bool accumulateConstantOffset(const DataLayout &DL, APInt &Offset) const;
 552 };
 553
 554 class PtrToIntOperator
 555     : public ConcreteOperator<Operator, Instruction::PtrToInt> {
 556   friend class PtrToInt;
 557   friend class ConstantExpr;
 558
 559 public:
 560   Value *getPointerOperand() {
 561     return getOperand(0);
 562   }
 563   const Value *getPointerOperand() const {
 564     return getOperand(0);
 565   }
 566
 567   static unsigned getPointerOperandIndex() {
 568     return 0U;                      // get index for modifying correct operand
 569   }
 570
 571   /// Method to return the pointer operand as a PointerType.
 572   Type *getPointerOperandType() const {
 573     return getPointerOperand()->getType();
 574   }
 575
 576   /// Method to return the address space of the pointer operand.
 577   unsigned getPointerAddressSpace() const {
 578     return cast<PointerType>(getPointerOperandType())->getAddressSpace();
 579   }
 580 };
 581
 582 class BitCastOperator
 583     : public ConcreteOperator<Operator, Instruction::BitCast> {
 584   friend class BitCastInst;
 585   friend class ConstantExpr;
 586
 587 public:
 588   Type *getSrcTy() const {
 589     return getOperand(0)->getType();
 590   }
 591
 592   Type *getDestTy() const {
 593     return getType();
 594   }
 595 };
 596
 597 } // end namespace llvm
 598
 599 #endif // LLVM_IR_OPERATOR_H