reference, declarationdefinition
definition → references, declarations, derived classes, virtual overrides
reference to multiple definitions → definitions
unreferenced
    1
    2
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
  100
  101
  102
  103
  104
  105
  106
  107
  108
  109
  110
  111
  112
  113
  114
  115
  116
  117
  118
  119
  120
  121
  122
  123
  124
  125
  126
  127
  128
  129
  130
  131
  132
  133
  134
  135
  136
  137
  138
  139
  140
  141
  142
  143
  144
  145
  146
  147
  148
  149
  150
  151
  152
  153
  154
  155
  156
  157
  158
  159
  160
  161
  162
  163
  164
  165
  166
  167
  168
  169
  170
  171
  172
  173
  174
  175
  176
  177
  178
  179
  180
  181
  182
  183
  184
  185
  186
  187
  188
  189
  190
  191
  192
  193
  194
  195
  196
  197
  198
  199
  200
  201
  202
  203
  204
  205
  206
  207
  208
  209
  210
//===----- ABI.h - ABI related declarations ---------------------*- 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
/// Enums/classes describing ABI related information about constructors,
/// destructors and thunks.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_BASIC_ABI_H
#define LLVM_CLANG_BASIC_ABI_H

#include "llvm/Support/DataTypes.h"
#include <cstring>

namespace clang {

/// C++ constructor types.
enum CXXCtorType {
  Ctor_Complete,       ///< Complete object ctor
  Ctor_Base,           ///< Base object ctor
  Ctor_Comdat,         ///< The COMDAT used for ctors
  Ctor_CopyingClosure, ///< Copying closure variant of a ctor
  Ctor_DefaultClosure, ///< Default closure variant of a ctor
};

/// C++ destructor types.
enum CXXDtorType {
    Dtor_Deleting, ///< Deleting dtor
    Dtor_Complete, ///< Complete object dtor
    Dtor_Base,     ///< Base object dtor
    Dtor_Comdat    ///< The COMDAT used for dtors
};

/// A return adjustment.
struct ReturnAdjustment {
  /// The non-virtual adjustment from the derived object to its
  /// nearest virtual base.
  int64_t NonVirtual;

  /// Holds the ABI-specific information about the virtual return
  /// adjustment, if needed.
  union VirtualAdjustment {
    // Itanium ABI
    struct {
      /// The offset (in bytes), relative to the address point
      /// of the virtual base class offset.
      int64_t VBaseOffsetOffset;
    } Itanium;

    // Microsoft ABI
    struct {
      /// The offset (in bytes) of the vbptr, relative to the beginning
      /// of the derived class.
      uint32_t VBPtrOffset;

      /// Index of the virtual base in the vbtable.
      uint32_t VBIndex;
    } Microsoft;

    VirtualAdjustment() {
      memset(this, 0, sizeof(*this));
    }

    bool Equals(const VirtualAdjustment &Other) const {
      return memcmp(this, &Other, sizeof(Other)) == 0;
    }

    bool isEmpty() const {
      VirtualAdjustment Zero;
      return Equals(Zero);
    }

    bool Less(const VirtualAdjustment &RHS) const {
      return memcmp(this, &RHS, sizeof(RHS)) < 0;
    }
  } Virtual;

  ReturnAdjustment() : NonVirtual(0) {}

  bool isEmpty() const { return !NonVirtual && Virtual.isEmpty(); }

  friend bool operator==(const ReturnAdjustment &LHS,
                         const ReturnAdjustment &RHS) {
    return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Equals(RHS.Virtual);
  }

  friend bool operator!=(const ReturnAdjustment &LHS, const ReturnAdjustment &RHS) {
    return !(LHS == RHS);
  }

  friend bool operator<(const ReturnAdjustment &LHS,
                        const ReturnAdjustment &RHS) {
    if (LHS.NonVirtual < RHS.NonVirtual)
      return true;

    return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Less(RHS.Virtual);
  }
};

/// A \c this pointer adjustment.
struct ThisAdjustment {
  /// The non-virtual adjustment from the derived object to its
  /// nearest virtual base.
  int64_t NonVirtual;

  /// Holds the ABI-specific information about the virtual this
  /// adjustment, if needed.
  union VirtualAdjustment {
    // Itanium ABI
    struct {
      /// The offset (in bytes), relative to the address point,
      /// of the virtual call offset.
      int64_t VCallOffsetOffset;
    } Itanium;

    struct {
      /// The offset of the vtordisp (in bytes), relative to the ECX.
      int32_t VtordispOffset;

      /// The offset of the vbptr of the derived class (in bytes),
      /// relative to the ECX after vtordisp adjustment.
      int32_t VBPtrOffset;

      /// The offset (in bytes) of the vbase offset in the vbtable.
      int32_t VBOffsetOffset;
    } Microsoft;

    VirtualAdjustment() {
      memset(this, 0, sizeof(*this));
    }

    bool Equals(const VirtualAdjustment &Other) const {
      return memcmp(this, &Other, sizeof(Other)) == 0;
    }

    bool isEmpty() const {
      VirtualAdjustment Zero;
      return Equals(Zero);
    }

    bool Less(const VirtualAdjustment &RHS) const {
      return memcmp(this, &RHS, sizeof(RHS)) < 0;
    }
  } Virtual;

  ThisAdjustment() : NonVirtual(0) { }

  bool isEmpty() const { return !NonVirtual && Virtual.isEmpty(); }

  friend bool operator==(const ThisAdjustment &LHS,
                         const ThisAdjustment &RHS) {
    return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Equals(RHS.Virtual);
  }

  friend bool operator!=(const ThisAdjustment &LHS, const ThisAdjustment &RHS) {
    return !(LHS == RHS);
  }

  friend bool operator<(const ThisAdjustment &LHS,
                        const ThisAdjustment &RHS) {
    if (LHS.NonVirtual < RHS.NonVirtual)
      return true;

    return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Less(RHS.Virtual);
  }
};

class CXXMethodDecl;

/// The \c this pointer adjustment as well as an optional return
/// adjustment for a thunk.
struct ThunkInfo {
  /// The \c this pointer adjustment.
  ThisAdjustment This;

  /// The return adjustment.
  ReturnAdjustment Return;

  /// Holds a pointer to the overridden method this thunk is for,
  /// if needed by the ABI to distinguish different thunks with equal
  /// adjustments. Otherwise, null.
  /// CAUTION: In the unlikely event you need to sort ThunkInfos, consider using
  /// an ABI-specific comparator.
  const CXXMethodDecl *Method;

  ThunkInfo() : Method(nullptr) { }

  ThunkInfo(const ThisAdjustment &This, const ReturnAdjustment &Return,
            const CXXMethodDecl *Method = nullptr)
      : This(This), Return(Return), Method(Method) {}

  friend bool operator==(const ThunkInfo &LHS, const ThunkInfo &RHS) {
    return LHS.This == RHS.This && LHS.Return == RHS.Return &&
           LHS.Method == RHS.Method;
  }

  bool isEmpty() const {
    return This.isEmpty() && Return.isEmpty() && Method == nullptr;
  }
};

} // end namespace clang

#endif