clang 18.0.0git
LayoutOverrideSource.cpp
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1//===--- LayoutOverrideSource.cpp --Override Record Layouts ---------------===//
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//===----------------------------------------------------------------------===//
9#include "clang/AST/Decl.h"
10#include "clang/AST/DeclCXX.h"
12#include "llvm/Support/raw_ostream.h"
13#include <fstream>
14#include <string>
15
16using namespace clang;
17
18/// Parse a simple identifier.
19static std::string parseName(StringRef S) {
20 if (S.empty() || !isAsciiIdentifierStart(S[0]))
21 return "";
22
23 unsigned Offset = 1;
24 while (Offset < S.size() && isAsciiIdentifierContinue(S[Offset]))
25 ++Offset;
26
27 return S.substr(0, Offset).str();
28}
29
30/// Parse an unsigned integer and move S to the next non-digit character.
31static bool parseUnsigned(StringRef &S, unsigned long long &ULL) {
32 if (S.empty() || !isDigit(S[0]))
33 return false;
34 unsigned Idx = 1;
35 while (Idx < S.size() && isDigit(S[Idx]))
36 ++Idx;
37 (void)S.substr(0, Idx).getAsInteger(10, ULL);
38 S = S.substr(Idx);
39 return true;
40}
41
43 std::ifstream Input(Filename.str().c_str());
44 if (!Input.is_open())
45 return;
46
47 // Parse the output of -fdump-record-layouts.
48 std::string CurrentType;
49 Layout CurrentLayout;
50 bool ExpectingType = false;
51
52 while (Input.good()) {
53 std::string Line;
54 getline(Input, Line);
55
56 StringRef LineStr(Line);
57
58 // Determine whether the following line will start a
59 if (LineStr.contains("*** Dumping AST Record Layout")) {
60 // Flush the last type/layout, if there is one.
61 if (!CurrentType.empty())
62 Layouts[CurrentType] = CurrentLayout;
63 CurrentLayout = Layout();
64
65 ExpectingType = true;
66 continue;
67 }
68
69 // If we're expecting a type, grab it.
70 if (ExpectingType) {
71 ExpectingType = false;
72
73 StringRef::size_type Pos;
74 if ((Pos = LineStr.find("struct ")) != StringRef::npos)
75 LineStr = LineStr.substr(Pos + strlen("struct "));
76 else if ((Pos = LineStr.find("class ")) != StringRef::npos)
77 LineStr = LineStr.substr(Pos + strlen("class "));
78 else if ((Pos = LineStr.find("union ")) != StringRef::npos)
79 LineStr = LineStr.substr(Pos + strlen("union "));
80 else
81 continue;
82
83 // Find the name of the type.
84 CurrentType = parseName(LineStr);
85 CurrentLayout = Layout();
86 continue;
87 }
88
89 // Check for the size of the type.
90 StringRef::size_type Pos = LineStr.find(" Size:");
91 if (Pos != StringRef::npos) {
92 // Skip past the " Size:" prefix.
93 LineStr = LineStr.substr(Pos + strlen(" Size:"));
94
95 unsigned long long Size = 0;
96 if (parseUnsigned(LineStr, Size))
97 CurrentLayout.Size = Size;
98 continue;
99 }
100
101 // Check for the alignment of the type.
102 Pos = LineStr.find("Alignment:");
103 if (Pos != StringRef::npos) {
104 // Skip past the "Alignment:" prefix.
105 LineStr = LineStr.substr(Pos + strlen("Alignment:"));
106
107 unsigned long long Alignment = 0;
108 if (parseUnsigned(LineStr, Alignment))
109 CurrentLayout.Align = Alignment;
110 continue;
111 }
112
113 // Check for the size/alignment of the type. The number follows "size=" or
114 // "align=" indicates number of bytes.
115 Pos = LineStr.find("sizeof=");
116 if (Pos != StringRef::npos) {
117 /* Skip past the sizeof= prefix. */
118 LineStr = LineStr.substr(Pos + strlen("sizeof="));
119
120 // Parse size.
121 unsigned long long Size = 0;
122 if (parseUnsigned(LineStr, Size))
123 CurrentLayout.Size = Size * 8;
124
125 Pos = LineStr.find("align=");
126 if (Pos != StringRef::npos) {
127 /* Skip past the align= prefix. */
128 LineStr = LineStr.substr(Pos + strlen("align="));
129
130 // Parse alignment.
131 unsigned long long Alignment = 0;
132 if (parseUnsigned(LineStr, Alignment))
133 CurrentLayout.Align = Alignment * 8;
134 }
135
136 continue;
137 }
138
139 // Check for the field offsets of the type.
140 Pos = LineStr.find("FieldOffsets: [");
141 if (Pos != StringRef::npos) {
142 LineStr = LineStr.substr(Pos + strlen("FieldOffsets: ["));
143 while (!LineStr.empty() && isDigit(LineStr[0])) {
144 unsigned long long Offset = 0;
145 if (parseUnsigned(LineStr, Offset))
146 CurrentLayout.FieldOffsets.push_back(Offset);
147
148 // Skip over this offset, the following comma, and any spaces.
149 LineStr = LineStr.substr(1);
150 while (!LineStr.empty() && isWhitespace(LineStr[0]))
151 LineStr = LineStr.substr(1);
152 }
153 }
154
155 // Check for the virtual base offsets.
156 Pos = LineStr.find("VBaseOffsets: [");
157 if (Pos != StringRef::npos) {
158 LineStr = LineStr.substr(Pos + strlen("VBaseOffsets: ["));
159 while (!LineStr.empty() && isDigit(LineStr[0])) {
160 unsigned long long Offset = 0;
161 if (parseUnsigned(LineStr, Offset))
162 CurrentLayout.VBaseOffsets.push_back(CharUnits::fromQuantity(Offset));
163
164 // Skip over this offset, the following comma, and any spaces.
165 LineStr = LineStr.substr(1);
166 while (!LineStr.empty() && isWhitespace(LineStr[0]))
167 LineStr = LineStr.substr(1);
168 }
169 continue;
170 }
171
172 // Check for the base offsets.
173 Pos = LineStr.find("BaseOffsets: [");
174 if (Pos != StringRef::npos) {
175 LineStr = LineStr.substr(Pos + strlen("BaseOffsets: ["));
176 while (!LineStr.empty() && isDigit(LineStr[0])) {
177 unsigned long long Offset = 0;
178 if (parseUnsigned(LineStr, Offset))
179 CurrentLayout.BaseOffsets.push_back(CharUnits::fromQuantity(Offset));
180
181 // Skip over this offset, the following comma, and any spaces.
182 LineStr = LineStr.substr(1);
183 while (!LineStr.empty() && isWhitespace(LineStr[0]))
184 LineStr = LineStr.substr(1);
185 }
186 }
187 }
188
189 // Flush the last type/layout, if there is one.
190 if (!CurrentType.empty())
191 Layouts[CurrentType] = CurrentLayout;
192}
193
194bool
196 uint64_t &Size, uint64_t &Alignment,
197 llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,
198 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,
199 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets)
200{
201 // We can't override unnamed declarations.
202 if (!Record->getIdentifier())
203 return false;
204
205 // Check whether we have a layout for this record.
206 llvm::StringMap<Layout>::iterator Known = Layouts.find(Record->getName());
207 if (Known == Layouts.end())
208 return false;
209
210 // Provide field layouts.
211 unsigned NumFields = 0;
212 for (RecordDecl::field_iterator F = Record->field_begin(),
213 FEnd = Record->field_end();
214 F != FEnd; ++F, ++NumFields) {
215 if (NumFields >= Known->second.FieldOffsets.size())
216 continue;
217
218 FieldOffsets[*F] = Known->second.FieldOffsets[NumFields];
219 }
220
221 // Wrong number of fields.
222 if (NumFields != Known->second.FieldOffsets.size())
223 return false;
224
225 // Provide base offsets.
226 if (const auto *RD = dyn_cast<CXXRecordDecl>(Record)) {
227 unsigned NumNB = 0;
228 unsigned NumVB = 0;
229 for (const auto &I : RD->vbases()) {
230 if (NumVB >= Known->second.VBaseOffsets.size())
231 continue;
232 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl();
233 VirtualBaseOffsets[VBase] = Known->second.VBaseOffsets[NumVB++];
234 }
235 for (const auto &I : RD->bases()) {
236 if (I.isVirtual() || NumNB >= Known->second.BaseOffsets.size())
237 continue;
238 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
239 BaseOffsets[Base] = Known->second.BaseOffsets[NumNB++];
240 }
241 }
242
243 Size = Known->second.Size;
244 Alignment = Known->second.Align;
245 return true;
246}
247
248LLVM_DUMP_METHOD void LayoutOverrideSource::dump() {
249 raw_ostream &OS = llvm::errs();
250 for (llvm::StringMap<Layout>::iterator L = Layouts.begin(),
251 LEnd = Layouts.end();
252 L != LEnd; ++L) {
253 OS << "Type: blah " << L->first() << '\n';
254 OS << " Size:" << L->second.Size << '\n';
255 OS << " Alignment:" << L->second.Align << '\n';
256 OS << " FieldOffsets: [";
257 for (unsigned I = 0, N = L->second.FieldOffsets.size(); I != N; ++I) {
258 if (I)
259 OS << ", ";
260 OS << L->second.FieldOffsets[I];
261 }
262 OS << "]\n";
263 }
264}
265
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate....
StringRef Filename
Definition: Format.cpp:2976
static bool parseUnsigned(StringRef &S, unsigned long long &ULL)
Parse an unsigned integer and move S to the next non-digit character.
static std::string parseName(StringRef S)
Parse a simple identifier.
Represents a C++ struct/union/class.
Definition: DeclCXX.h:258
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
specific_decl_iterator - Iterates over a subrange of declarations stored in a DeclContext,...
Definition: DeclBase.h:2340
bool layoutRecordType(const RecordDecl *Record, uint64_t &Size, uint64_t &Alignment, llvm::DenseMap< const FieldDecl *, uint64_t > &FieldOffsets, llvm::DenseMap< const CXXRecordDecl *, CharUnits > &BaseOffsets, llvm::DenseMap< const CXXRecordDecl *, CharUnits > &VirtualBaseOffsets) override
If this particular record type has an overridden layout, return that layout.
void dump()
Dump the overridden layouts.
LayoutOverrideSource(StringRef Filename)
Create a new AST source that overrides the layout of some set of record types.
Represents a struct/union/class.
Definition: Decl.h:4117
LLVM_READONLY bool isDigit(unsigned char c)
Return true if this character is an ASCII digit: [0-9].
Definition: CharInfo.h:99
LLVM_READONLY bool isWhitespace(unsigned char c)
Return true if this character is horizontal or vertical ASCII whitespace: ' ', '\t',...
Definition: CharInfo.h:93
LLVM_READONLY bool isAsciiIdentifierContinue(unsigned char c, bool AllowDollar=false)
Returns true if this is a body character of a C identifier, which is [a-zA-Z0-9_].
Definition: CharInfo.h:64
LLVM_READONLY bool isAsciiIdentifierStart(unsigned char c, bool AllowDollar=false)
Returns true if this is a valid first character of a C identifier, which is [a-zA-Z_].
Definition: CharInfo.h:54