Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- llvm/ADT/PointerIntPair.h - Pair for pointer and int -----*- 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

//

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

///

/// \file

/// This file defines the PointerIntPair class.

///

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

#ifndef LLVM_ADT_POINTERINTPAIR_H

#define LLVM_ADT_POINTERINTPAIR_H

#include "llvm/Support/Compiler.h"

#include "llvm/Support/PointerLikeTypeTraits.h"

#include "llvm/Support/type_traits.h"

#include <cassert>

#include <cstdint>

#include <limits>

namespace llvm {

template <typename T, typename Enable> struct DenseMapInfo;

template <typename PointerT, unsigned IntBits, typename PtrTraits>

struct PointerIntPairInfo;

/// PointerIntPair - This class implements a pair of a pointer and small

/// integer.  It is designed to represent this in the space required by one

/// pointer by bitmangling the integer into the low part of the pointer.  This

/// can only be done for small integers: typically up to 3 bits, but it depends

/// on the number of bits available according to PointerLikeTypeTraits for the

/// type.

///

/// Note that PointerIntPair always puts the IntVal part in the highest bits

/// possible.  For example, PointerIntPair<void*, 1, bool> will put the bit for

/// the bool into bit #2, not bit #0, which allows the low two bits to be used

/// for something else.  For example, this allows:

///   PointerIntPair<PointerIntPair<void*, 1, bool>, 1, bool>

/// ... and the two bools will land in different bits.

template <typename PointerTy, unsigned IntBits, typename IntType = unsigned,

          typename PtrTraits = PointerLikeTypeTraits<PointerTy>,

          typename Info = PointerIntPairInfo<PointerTy, IntBits, PtrTraits>>

class PointerIntPair {

  // Used by MSVC visualizer and generally helpful for debugging/visualizing.

  using InfoTy = Info;

  intptr_t Value = 0;

public:

  constexpr PointerIntPair() = default;

  PointerIntPair(PointerTy PtrVal, IntType IntVal) {

    setPointerAndInt(PtrVal, IntVal);

  }

  explicit PointerIntPair(PointerTy PtrVal) { initWithPointer(PtrVal); }

  PointerTy getPointer() const { return Info::getPointer(Value); }

  IntType getInt() const { return (IntType)Info::getInt(Value); }

  void setPointer(PointerTy PtrVal) & {

    Value = Info::updatePointer(Value, PtrVal);

  }

  void setInt(IntType IntVal) & {

    Value = Info::updateInt(Value, static_cast<intptr_t>(IntVal));

  }

  void initWithPointer(PointerTy PtrVal) & {

    Value = Info::updatePointer(0, PtrVal);

  }

  void setPointerAndInt(PointerTy PtrVal, IntType IntVal) & {

    Value = Info::updateInt(Info::updatePointer(0, PtrVal),

                            static_cast<intptr_t>(IntVal));

  }

  PointerTy const *getAddrOfPointer() const {

    return const_cast<PointerIntPair *>(this)->getAddrOfPointer();

  }

  PointerTy *getAddrOfPointer() {

    assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&

           "Can only return the address if IntBits is cleared and "

           "PtrTraits doesn't change the pointer");

    return reinterpret_cast<PointerTy *>(&Value);

  }

  void *getOpaqueValue() const { return reinterpret_cast<void *>(Value); }

  void setFromOpaqueValue(void *Val) & {

    Value = reinterpret_cast<intptr_t>(Val);

  }

  static PointerIntPair getFromOpaqueValue(void *V) {

    PointerIntPair P;

    P.setFromOpaqueValue(V);

    return P;

  }

  // Allow PointerIntPairs to be created from const void * if and only if the

  // pointer type could be created from a const void *.

  static PointerIntPair getFromOpaqueValue(const void *V) {

    (void)PtrTraits::getFromVoidPointer(V);

    return getFromOpaqueValue(const_cast<void *>(V));

  }

  bool operator==(const PointerIntPair &RHS) const {

    return Value == RHS.Value;

  }

  bool operator!=(const PointerIntPair &RHS) const {

    return Value != RHS.Value;

  }

  bool operator<(const PointerIntPair &RHS) const { return Value < RHS.Value; }

  bool operator>(const PointerIntPair &RHS) const { return Value > RHS.Value; }

  bool operator<=(const PointerIntPair &RHS) const {

    return Value <= RHS.Value;

  }

  bool operator>=(const PointerIntPair &RHS) const {

    return Value >= RHS.Value;

  }

};

template <typename PointerT, unsigned IntBits, typename PtrTraits>

struct PointerIntPairInfo {

  static_assert(PtrTraits::NumLowBitsAvailable <

                    std::numeric_limits<uintptr_t>::digits,

                "cannot use a pointer type that has all bits free");

  static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,

                "PointerIntPair with integer size too large for pointer");

  enum MaskAndShiftConstants : uintptr_t {

    /// PointerBitMask - The bits that come from the pointer.

    PointerBitMask =

        ~(uintptr_t)(((intptr_t)1 << PtrTraits::NumLowBitsAvailable) - 1),

    /// IntShift - The number of low bits that we reserve for other uses, and

    /// keep zero.

    IntShift = (uintptr_t)PtrTraits::NumLowBitsAvailable - IntBits,

    /// IntMask - This is the unshifted mask for valid bits of the int type.

    IntMask = (uintptr_t)(((intptr_t)1 << IntBits) - 1),

    // ShiftedIntMask - This is the bits for the integer shifted in place.

    ShiftedIntMask = (uintptr_t)(IntMask << IntShift)

  };

  static PointerT getPointer(intptr_t Value) {

    return PtrTraits::getFromVoidPointer(

        reinterpret_cast<void *>(Value & PointerBitMask));

  }

  static intptr_t getInt(intptr_t Value) {

    return (Value >> IntShift) & IntMask;

  }

  static intptr_t updatePointer(intptr_t OrigValue, PointerT Ptr) {

    intptr_t PtrWord =

        reinterpret_cast<intptr_t>(PtrTraits::getAsVoidPointer(Ptr));

    assert((PtrWord & ~PointerBitMask) == 0 &&

           "Pointer is not sufficiently aligned");

    // Preserve all low bits, just update the pointer.

    return PtrWord | (OrigValue & ~PointerBitMask);

  }

  static intptr_t updateInt(intptr_t OrigValue, intptr_t Int) {

    intptr_t IntWord = static_cast<intptr_t>(Int);

    assert((IntWord & ~IntMask) == 0 && "Integer too large for field");

    // Preserve all bits other than the ones we are updating.

    return (OrigValue & ~ShiftedIntMask) | IntWord << IntShift;

  }

};

// Provide specialization of DenseMapInfo for PointerIntPair.

template <typename PointerTy, unsigned IntBits, typename IntType>

struct DenseMapInfo<PointerIntPair<PointerTy, IntBits, IntType>, void> {

  using Ty = PointerIntPair<PointerTy, IntBits, IntType>;

  static Ty getEmptyKey() {

    uintptr_t Val = static_cast<uintptr_t>(-1);

    Val <<= PointerLikeTypeTraits<Ty>::NumLowBitsAvailable;

    return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));

  }

  static Ty getTombstoneKey() {

    uintptr_t Val = static_cast<uintptr_t>(-2);

    Val <<= PointerLikeTypeTraits<PointerTy>::NumLowBitsAvailable;

    return Ty::getFromOpaqueValue(reinterpret_cast<void *>(Val));

  }

  static unsigned getHashValue(Ty V) {

    uintptr_t IV = reinterpret_cast<uintptr_t>(V.getOpaqueValue());

    return unsigned(IV) ^ unsigned(IV >> 9);

  }

  static bool isEqual(const Ty &LHS, const Ty &RHS) { return LHS == RHS; }

};

// Teach SmallPtrSet that PointerIntPair is "basically a pointer".

template <typename PointerTy, unsigned IntBits, typename IntType,

          typename PtrTraits>

struct PointerLikeTypeTraits<

    PointerIntPair<PointerTy, IntBits, IntType, PtrTraits>> {

  static inline void *

  getAsVoidPointer(const PointerIntPair<PointerTy, IntBits, IntType> &P) {

    return P.getOpaqueValue();

  }

  static inline PointerIntPair<PointerTy, IntBits, IntType>

  getFromVoidPointer(void *P) {

    return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);

  }

  static inline PointerIntPair<PointerTy, IntBits, IntType>

  getFromVoidPointer(const void *P) {

    return PointerIntPair<PointerTy, IntBits, IntType>::getFromOpaqueValue(P);

  }

  static constexpr int NumLowBitsAvailable =

      PtrTraits::NumLowBitsAvailable - IntBits;

};

// Allow structured bindings on PointerIntPair.

template <std::size_t I, typename PointerTy, unsigned IntBits, typename IntType,

          typename PtrTraits, typename Info>

decltype(auto)

get(const PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info> &Pair) {

  static_assert(I < 2);

  if constexpr (I == 0)

    return Pair.getPointer();

  else

    return Pair.getInt();

}

} // end namespace llvm

namespace std {

template <typename PointerTy, unsigned IntBits, typename IntType,

          typename PtrTraits, typename Info>

struct tuple_size<

    llvm::PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>

    : std::integral_constant<std::size_t, 2> {};

template <std::size_t I, typename PointerTy, unsigned IntBits, typename IntType,

          typename PtrTraits, typename Info>

struct tuple_element<

    I, llvm::PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>

    : std::conditional<I == 0, PointerTy, IntType> {};

} // namespace std

#endif // LLVM_ADT_POINTERINTPAIR_H