1 | //===----- Thunk.h - Declarations related to VTable Thunks ------*- 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 | /// \file |
10 | /// Enums/classes describing THUNK related information about constructors, |
11 | /// destructors and thunks. |
12 | /// |
13 | //===----------------------------------------------------------------------===// |
14 | |
15 | #ifndef LLVM_CLANG_BASIC_THUNK_H |
16 | #define LLVM_CLANG_BASIC_THUNK_H |
17 | |
18 | #include <cstdint> |
19 | #include <cstring> |
20 | |
21 | namespace clang { |
22 | |
23 | class CXXMethodDecl; |
24 | |
25 | /// A return adjustment. |
26 | struct ReturnAdjustment { |
27 | /// The non-virtual adjustment from the derived object to its |
28 | /// nearest virtual base. |
29 | int64_t NonVirtual = 0; |
30 | |
31 | /// Holds the ABI-specific information about the virtual return |
32 | /// adjustment, if needed. |
33 | union VirtualAdjustment { |
34 | // Itanium ABI |
35 | struct { |
36 | /// The offset (in bytes), relative to the address point |
37 | /// of the virtual base class offset. |
38 | int64_t VBaseOffsetOffset; |
39 | } Itanium; |
40 | |
41 | // Microsoft ABI |
42 | struct { |
43 | /// The offset (in bytes) of the vbptr, relative to the beginning |
44 | /// of the derived class. |
45 | uint32_t VBPtrOffset; |
46 | |
47 | /// Index of the virtual base in the vbtable. |
48 | uint32_t VBIndex; |
49 | } Microsoft; |
50 | |
51 | VirtualAdjustment() { memset(s: this, c: 0, n: sizeof(*this)); } |
52 | |
53 | bool Equals(const VirtualAdjustment &Other) const { |
54 | return memcmp(s1: this, s2: &Other, n: sizeof(Other)) == 0; |
55 | } |
56 | |
57 | bool isEmpty() const { |
58 | VirtualAdjustment Zero; |
59 | return Equals(Other: Zero); |
60 | } |
61 | |
62 | bool Less(const VirtualAdjustment &RHS) const { |
63 | return memcmp(s1: this, s2: &RHS, n: sizeof(RHS)) < 0; |
64 | } |
65 | } Virtual; |
66 | |
67 | ReturnAdjustment() = default; |
68 | |
69 | bool isEmpty() const { return !NonVirtual && Virtual.isEmpty(); } |
70 | |
71 | friend bool operator==(const ReturnAdjustment &LHS, |
72 | const ReturnAdjustment &RHS) { |
73 | return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Equals(Other: RHS.Virtual); |
74 | } |
75 | |
76 | friend bool operator!=(const ReturnAdjustment &LHS, |
77 | const ReturnAdjustment &RHS) { |
78 | return !(LHS == RHS); |
79 | } |
80 | |
81 | friend bool operator<(const ReturnAdjustment &LHS, |
82 | const ReturnAdjustment &RHS) { |
83 | if (LHS.NonVirtual < RHS.NonVirtual) |
84 | return true; |
85 | |
86 | return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Less(RHS: RHS.Virtual); |
87 | } |
88 | }; |
89 | |
90 | /// A \c this pointer adjustment. |
91 | struct ThisAdjustment { |
92 | /// The non-virtual adjustment from the derived object to its |
93 | /// nearest virtual base. |
94 | int64_t NonVirtual = 0; |
95 | |
96 | /// Holds the ABI-specific information about the virtual this |
97 | /// adjustment, if needed. |
98 | union VirtualAdjustment { |
99 | // Itanium ABI |
100 | struct { |
101 | /// The offset (in bytes), relative to the address point, |
102 | /// of the virtual call offset. |
103 | int64_t VCallOffsetOffset; |
104 | } Itanium; |
105 | |
106 | struct { |
107 | /// The offset of the vtordisp (in bytes), relative to the ECX. |
108 | int32_t VtordispOffset; |
109 | |
110 | /// The offset of the vbptr of the derived class (in bytes), |
111 | /// relative to the ECX after vtordisp adjustment. |
112 | int32_t VBPtrOffset; |
113 | |
114 | /// The offset (in bytes) of the vbase offset in the vbtable. |
115 | int32_t VBOffsetOffset; |
116 | } Microsoft; |
117 | |
118 | VirtualAdjustment() { memset(s: this, c: 0, n: sizeof(*this)); } |
119 | |
120 | bool Equals(const VirtualAdjustment &Other) const { |
121 | return memcmp(s1: this, s2: &Other, n: sizeof(Other)) == 0; |
122 | } |
123 | |
124 | bool isEmpty() const { |
125 | VirtualAdjustment Zero; |
126 | return Equals(Other: Zero); |
127 | } |
128 | |
129 | bool Less(const VirtualAdjustment &RHS) const { |
130 | return memcmp(s1: this, s2: &RHS, n: sizeof(RHS)) < 0; |
131 | } |
132 | } Virtual; |
133 | |
134 | ThisAdjustment() = default; |
135 | |
136 | bool isEmpty() const { return !NonVirtual && Virtual.isEmpty(); } |
137 | |
138 | friend bool operator==(const ThisAdjustment &LHS, const ThisAdjustment &RHS) { |
139 | return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Equals(Other: RHS.Virtual); |
140 | } |
141 | |
142 | friend bool operator!=(const ThisAdjustment &LHS, const ThisAdjustment &RHS) { |
143 | return !(LHS == RHS); |
144 | } |
145 | |
146 | friend bool operator<(const ThisAdjustment &LHS, const ThisAdjustment &RHS) { |
147 | if (LHS.NonVirtual < RHS.NonVirtual) |
148 | return true; |
149 | |
150 | return LHS.NonVirtual == RHS.NonVirtual && LHS.Virtual.Less(RHS: RHS.Virtual); |
151 | } |
152 | }; |
153 | |
154 | /// The \c this pointer adjustment as well as an optional return |
155 | /// adjustment for a thunk. |
156 | struct ThunkInfo { |
157 | /// The \c this pointer adjustment. |
158 | ThisAdjustment This; |
159 | |
160 | /// The return adjustment. |
161 | ReturnAdjustment Return; |
162 | |
163 | /// Holds a pointer to the overridden method this thunk is for, |
164 | /// if needed by the ABI to distinguish different thunks with equal |
165 | /// adjustments. Otherwise, null. |
166 | /// CAUTION: In the unlikely event you need to sort ThunkInfos, consider using |
167 | /// an ABI-specific comparator. |
168 | const CXXMethodDecl *Method; |
169 | |
170 | ThunkInfo() : Method(nullptr) {} |
171 | |
172 | ThunkInfo(const ThisAdjustment &This, const ReturnAdjustment &Return, |
173 | const CXXMethodDecl *Method = nullptr) |
174 | : This(This), Return(Return), Method(Method) {} |
175 | |
176 | friend bool operator==(const ThunkInfo &LHS, const ThunkInfo &RHS) { |
177 | return LHS.This == RHS.This && LHS.Return == RHS.Return && |
178 | LHS.Method == RHS.Method; |
179 | } |
180 | |
181 | bool isEmpty() const { |
182 | return This.isEmpty() && Return.isEmpty() && Method == nullptr; |
183 | } |
184 | }; |
185 | |
186 | } // end namespace clang |
187 | |
188 | #endif |
189 | |