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//===-- llvm/Operator.h - Operator utility subclass -------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file defines various classes for working with Instructions and

// ConstantExprs.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_OPERATOR_H

#define LLVM_IR_OPERATOR_H

#include "llvm/ADT/MapVector.h"

#include "llvm/IR/Constants.h"

#include "llvm/IR/FMF.h"

#include "llvm/IR/Instruction.h"

#include "llvm/IR/Type.h"

#include "llvm/IR/Value.h"

#include "llvm/Support/Casting.h"

#include <cstddef>

#include <optional>

namespace llvm {

/// This is a utility class that provides an abstraction for the common

/// functionality between Instructions and ConstantExprs.

class Operator : public User {

public:

  // The Operator class is intended to be used as a utility, and is never itself

  // instantiated.

  Operator() = delete;

  ~Operator() = delete;

  void *operator new(size_t s) = delete;

  /// Return the opcode for this Instruction or ConstantExpr.

  unsigned getOpcode() const {

    if (const Instruction *I = dyn_cast<Instruction>(this))

      return I->getOpcode();

    return cast<ConstantExpr>(this)->getOpcode();

  }

  /// If V is an Instruction or ConstantExpr, return its opcode.

  /// Otherwise return UserOp1.

  static unsigned getOpcode(const Value *V) {

    if (const Instruction *I = dyn_cast<Instruction>(V))

      return I->getOpcode();

    if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))

      return CE->getOpcode();

    return Instruction::UserOp1;

  }

  static bool classof(const Instruction *) { return true; }

  static bool classof(const ConstantExpr *) { return true; }

  static bool classof(const Value *V) {

    return isa<Instruction>(V) || isa<ConstantExpr>(V);

  }

  /// Return true if this operator has flags which may cause this operator

  /// to evaluate to poison despite having non-poison inputs.

  bool hasPoisonGeneratingFlags() const;

  /// Return true if this operator has poison-generating flags or metadata.

  /// The latter is only possible for instructions.

  bool hasPoisonGeneratingFlagsOrMetadata() const;

};

/// Utility class for integer operators which may exhibit overflow - Add, Sub,

/// Mul, and Shl. It does not include SDiv, despite that operator having the

/// potential for overflow.

class OverflowingBinaryOperator : public Operator {

public:

  enum {

    AnyWrap        = 0,

    NoUnsignedWrap = (1 << 0),

    NoSignedWrap   = (1 << 1)

  };

private:

  friend class Instruction;

  friend class ConstantExpr;

  void setHasNoUnsignedWrap(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap);

  }

  void setHasNoSignedWrap(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap);

  }

public:

  /// Test whether this operation is known to never

  /// undergo unsigned overflow, aka the nuw property.

  bool hasNoUnsignedWrap() const {

    return SubclassOptionalData & NoUnsignedWrap;

  }

  /// Test whether this operation is known to never

  /// undergo signed overflow, aka the nsw property.

  bool hasNoSignedWrap() const {

    return (SubclassOptionalData & NoSignedWrap) != 0;

  }

  static bool classof(const Instruction *I) {

    return I->getOpcode() == Instruction::Add ||

           I->getOpcode() == Instruction::Sub ||

           I->getOpcode() == Instruction::Mul ||

           I->getOpcode() == Instruction::Shl;

  }

  static bool classof(const ConstantExpr *CE) {

    return CE->getOpcode() == Instruction::Add ||

           CE->getOpcode() == Instruction::Sub ||

           CE->getOpcode() == Instruction::Mul ||

           CE->getOpcode() == Instruction::Shl;

  }

  static bool classof(const Value *V) {

    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||

           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));

  }

};

/// A udiv or sdiv instruction, which can be marked as "exact",

/// indicating that no bits are destroyed.

class PossiblyExactOperator : public Operator {

public:

  enum {

    IsExact = (1 << 0)

  };

private:

  friend class Instruction;

  friend class ConstantExpr;

  void setIsExact(bool B) {

    SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact);

  }

public:

  /// Test whether this division is known to be exact, with zero remainder.

  bool isExact() const {

    return SubclassOptionalData & IsExact;

  }

  static bool isPossiblyExactOpcode(unsigned OpC) {

    return OpC == Instruction::SDiv ||

           OpC == Instruction::UDiv ||

           OpC == Instruction::AShr ||

           OpC == Instruction::LShr;

  }

  static bool classof(const ConstantExpr *CE) {

    return isPossiblyExactOpcode(CE->getOpcode());

  }

  static bool classof(const Instruction *I) {

    return isPossiblyExactOpcode(I->getOpcode());

  }

  static bool classof(const Value *V) {

    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||

           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));

  }

};

/// Utility class for floating point operations which can have

/// information about relaxed accuracy requirements attached to them.

class FPMathOperator : public Operator {

private:

  friend class Instruction;

  /// 'Fast' means all bits are set.

  void setFast(bool B) {

    setHasAllowReassoc(B);

    setHasNoNaNs(B);

    setHasNoInfs(B);

    setHasNoSignedZeros(B);

    setHasAllowReciprocal(B);

    setHasAllowContract(B);

    setHasApproxFunc(B);

  }

  void setHasAllowReassoc(bool B) {

    SubclassOptionalData =

    (SubclassOptionalData & ~FastMathFlags::AllowReassoc) |

    (B * FastMathFlags::AllowReassoc);

  }

  void setHasNoNaNs(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~FastMathFlags::NoNaNs) |

      (B * FastMathFlags::NoNaNs);

  }

  void setHasNoInfs(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~FastMathFlags::NoInfs) |

      (B * FastMathFlags::NoInfs);

  }

  void setHasNoSignedZeros(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) |

      (B * FastMathFlags::NoSignedZeros);

  }

  void setHasAllowReciprocal(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) |

      (B * FastMathFlags::AllowReciprocal);

  }

  void setHasAllowContract(bool B) {

    SubclassOptionalData =

        (SubclassOptionalData & ~FastMathFlags::AllowContract) |

        (B * FastMathFlags::AllowContract);

  }

  void setHasApproxFunc(bool B) {

    SubclassOptionalData =

        (SubclassOptionalData & ~FastMathFlags::ApproxFunc) |

        (B * FastMathFlags::ApproxFunc);

  }

  /// Convenience function for setting multiple fast-math flags.

  /// FMF is a mask of the bits to set.

  void setFastMathFlags(FastMathFlags FMF) {

    SubclassOptionalData |= FMF.Flags;

  }

  /// Convenience function for copying all fast-math flags.

  /// All values in FMF are transferred to this operator.

  void copyFastMathFlags(FastMathFlags FMF) {

    SubclassOptionalData = FMF.Flags;

  }

public:

  /// Test if this operation allows all non-strict floating-point transforms.

  bool isFast() const {

    return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 &&

            (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 &&

            (SubclassOptionalData & FastMathFlags::NoInfs) != 0 &&

            (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 &&

            (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 &&

            (SubclassOptionalData & FastMathFlags::AllowContract) != 0 &&

            (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0);

  }

  /// Test if this operation may be simplified with reassociative transforms.

  bool hasAllowReassoc() const {

    return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0;

  }

  /// Test if this operation's arguments and results are assumed not-NaN.

  bool hasNoNaNs() const {

    return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0;

  }

  /// Test if this operation's arguments and results are assumed not-infinite.

  bool hasNoInfs() const {

    return (SubclassOptionalData & FastMathFlags::NoInfs) != 0;

  }

  /// Test if this operation can ignore the sign of zero.

  bool hasNoSignedZeros() const {

    return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0;

  }

  /// Test if this operation can use reciprocal multiply instead of division.

  bool hasAllowReciprocal() const {

    return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0;

  }

  /// Test if this operation can be floating-point contracted (FMA).

  bool hasAllowContract() const {

    return (SubclassOptionalData & FastMathFlags::AllowContract) != 0;

  }

  /// Test if this operation allows approximations of math library functions or

  /// intrinsics.

  bool hasApproxFunc() const {

    return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0;

  }

  /// Convenience function for getting all the fast-math flags

  FastMathFlags getFastMathFlags() const {

    return FastMathFlags(SubclassOptionalData);

  }

  /// Get the maximum error permitted by this operation in ULPs. An accuracy of

  /// 0.0 means that the operation should be performed with the default

  /// precision.

  float getFPAccuracy() const;

  static bool classof(const Value *V) {

    unsigned Opcode;

    if (auto *I = dyn_cast<Instruction>(V))

      Opcode = I->getOpcode();

    else if (auto *CE = dyn_cast<ConstantExpr>(V))

      Opcode = CE->getOpcode();

    else

      return false;

    switch (Opcode) {

    case Instruction::FNeg:

    case Instruction::FAdd:

    case Instruction::FSub:

    case Instruction::FMul:

    case Instruction::FDiv:

    case Instruction::FRem:

    // FIXME: To clean up and correct the semantics of fast-math-flags, FCmp

    //        should not be treated as a math op, but the other opcodes should.

    //        This would make things consistent with Select/PHI (FP value type

    //        determines whether they are math ops and, therefore, capable of

    //        having fast-math-flags).

    case Instruction::FCmp:

      return true;

    case Instruction::PHI:

    case Instruction::Select:

    case Instruction::Call: {

      Type *Ty = V->getType();

      while (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty))

        Ty = ArrTy->getElementType();

      return Ty->isFPOrFPVectorTy();

    }

    default:

      return false;

    }

  }

};

/// A helper template for defining operators for individual opcodes.

template<typename SuperClass, unsigned Opc>

class ConcreteOperator : public SuperClass {

public:

  static bool classof(const Instruction *I) {

    return I->getOpcode() == Opc;

  }

  static bool classof(const ConstantExpr *CE) {

    return CE->getOpcode() == Opc;

  }

  static bool classof(const Value *V) {

    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||

           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));

  }

};

class AddOperator

  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> {

};

class SubOperator

  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> {

};

class MulOperator

  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> {

};

class ShlOperator

  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> {

};

class SDivOperator

  : public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> {

};

class UDivOperator

  : public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> {

};

class AShrOperator

  : public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> {

};

class LShrOperator

  : public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> {

};

class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {};

class GEPOperator

  : public ConcreteOperator<Operator, Instruction::GetElementPtr> {

  friend class GetElementPtrInst;

  friend class ConstantExpr;

  enum {

    IsInBounds = (1 << 0),

    // InRangeIndex: bits 1-6

  };

  void setIsInBounds(bool B) {

    SubclassOptionalData =

      (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds);

  }

public:

  /// Test whether this is an inbounds GEP, as defined by LangRef.html.

  bool isInBounds() const {

    return SubclassOptionalData & IsInBounds;

  }

  /// Returns the offset of the index with an inrange attachment, or

  /// std::nullopt if none.

  std::optional<unsigned> getInRangeIndex() const {

    if (SubclassOptionalData >> 1 == 0)

      return std::nullopt;

    return (SubclassOptionalData >> 1) - 1;

  }

  inline op_iterator       idx_begin()       { return op_begin()+1; }

  inline const_op_iterator idx_begin() const { return op_begin()+1; }

  inline op_iterator       idx_end()         { return op_end(); }

  inline const_op_iterator idx_end()   const { return op_end(); }

  inline iterator_range<op_iterator> indices() {

    return make_range(idx_begin(), idx_end());

  }

  inline iterator_range<const_op_iterator> indices() const {

    return make_range(idx_begin(), idx_end());

  }

  Value *getPointerOperand() {

    return getOperand(0);

  }

  const Value *getPointerOperand() const {

    return getOperand(0);

  }

  static unsigned getPointerOperandIndex() {

    return 0U;                      // get index for modifying correct operand

  }

  /// Method to return the pointer operand as a PointerType.

  Type *getPointerOperandType() const {

    return getPointerOperand()->getType();

  }

  Type *getSourceElementType() const;

  Type *getResultElementType() const;

  /// Method to return the address space of the pointer operand.

  unsigned getPointerAddressSpace() const {

    return getPointerOperandType()->getPointerAddressSpace();

  }

  unsigned getNumIndices() const {  // Note: always non-negative

    return getNumOperands() - 1;

  }

  bool hasIndices() const {

    return getNumOperands() > 1;

  }

  /// Return true if all of the indices of this GEP are zeros.

  /// If so, the result pointer and the first operand have the same

  /// value, just potentially different types.

  bool hasAllZeroIndices() const {

    for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {

      if (ConstantInt *C = dyn_cast<ConstantInt>(I))

        if (C->isZero())

          continue;

      return false;

    }

    return true;

  }

  /// Return true if all of the indices of this GEP are constant integers.

  /// If so, the result pointer and the first operand have

  /// a constant offset between them.

  bool hasAllConstantIndices() const {

    for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {

      if (!isa<ConstantInt>(I))

        return false;

    }

    return true;

  }

  unsigned countNonConstantIndices() const {

    return count_if(indices(), [](const Use& use) {

        return !isa<ConstantInt>(*use);

      });

  }

  /// Compute the maximum alignment that this GEP is garranteed to preserve.

  Align getMaxPreservedAlignment(const DataLayout &DL) const;

  /// Accumulate the constant address offset of this GEP if possible.

  ///

  /// This routine accepts an APInt into which it will try to accumulate the

  /// constant offset of this GEP.

  ///

  /// If \p ExternalAnalysis is provided it will be used to calculate a offset

  /// when a operand of GEP is not constant.

  /// For example, for a value \p ExternalAnalysis might try to calculate a

  /// lower bound. If \p ExternalAnalysis is successful, it should return true.

  ///

  /// If the \p ExternalAnalysis returns false or the value returned by \p

  /// ExternalAnalysis results in a overflow/underflow, this routine returns

  /// false and the value of the offset APInt is undefined (it is *not*

  /// preserved!).

  ///

  /// The APInt passed into this routine must be at exactly as wide as the

  /// IntPtr type for the address space of the base GEP pointer.

  bool accumulateConstantOffset(

      const DataLayout &DL, APInt &Offset,

      function_ref<bool(Value &, APInt &)> ExternalAnalysis = nullptr) const;

  static bool accumulateConstantOffset(

      Type *SourceType, ArrayRef<const Value *> Index, const DataLayout &DL,

      APInt &Offset,

      function_ref<bool(Value &, APInt &)> ExternalAnalysis = nullptr);

  /// Collect the offset of this GEP as a map of Values to their associated

  /// APInt multipliers, as well as a total Constant Offset.

  bool collectOffset(const DataLayout &DL, unsigned BitWidth,

                     MapVector<Value *, APInt> &VariableOffsets,

                     APInt &ConstantOffset) const;

};

class PtrToIntOperator

    : public ConcreteOperator<Operator, Instruction::PtrToInt> {

  friend class PtrToInt;

  friend class ConstantExpr;

public:

  Value *getPointerOperand() {

    return getOperand(0);

  }

  const Value *getPointerOperand() const {

    return getOperand(0);

  }

  static unsigned getPointerOperandIndex() {

    return 0U;                      // get index for modifying correct operand

  }

  /// Method to return the pointer operand as a PointerType.

  Type *getPointerOperandType() const {

    return getPointerOperand()->getType();

  }

  /// Method to return the address space of the pointer operand.

  unsigned getPointerAddressSpace() const {

    return cast<PointerType>(getPointerOperandType())->getAddressSpace();

  }

};

class BitCastOperator

    : public ConcreteOperator<Operator, Instruction::BitCast> {

  friend class BitCastInst;

  friend class ConstantExpr;

public:

  Type *getSrcTy() const {

    return getOperand(0)->getType();

  }

  Type *getDestTy() const {

    return getType();

  }

};

class AddrSpaceCastOperator

    : public ConcreteOperator<Operator, Instruction::AddrSpaceCast> {

  friend class AddrSpaceCastInst;

  friend class ConstantExpr;

public:

  Value *getPointerOperand() { return getOperand(0); }

  const Value *getPointerOperand() const { return getOperand(0); }

  unsigned getSrcAddressSpace() const {

    return getPointerOperand()->getType()->getPointerAddressSpace();

  }

  unsigned getDestAddressSpace() const {

    return getType()->getPointerAddressSpace();

  }

};

} // end namespace llvm

#endif // LLVM_IR_OPERATOR_H