1 //===--- LayoutOverrideSource.cpp --Override Record Layouts ---------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 #include "clang/Frontend/LayoutOverrideSource.h"
10 #include "clang/AST/Decl.h"
11 #include "clang/Basic/CharInfo.h"
12 #include "llvm/Support/raw_ostream.h"
13 #include <fstream>
14 #include <string>
15
16 using namespace clang;
17
18 /// \brief Parse a simple identifier.
parseName(StringRef S)19 static std::string parseName(StringRef S) {
20 if (S.empty() || !isIdentifierHead(S[0]))
21 return "";
22
23 unsigned Offset = 1;
24 while (Offset < S.size() && isIdentifierBody(S[Offset]))
25 ++Offset;
26
27 return S.substr(0, Offset).str();
28 }
29
LayoutOverrideSource(StringRef Filename)30 LayoutOverrideSource::LayoutOverrideSource(StringRef Filename) {
31 std::ifstream Input(Filename.str().c_str());
32 if (!Input.is_open())
33 return;
34
35 // Parse the output of -fdump-record-layouts.
36 std::string CurrentType;
37 Layout CurrentLayout;
38 bool ExpectingType = false;
39
40 while (Input.good()) {
41 std::string Line;
42 getline(Input, Line);
43
44 StringRef LineStr(Line);
45
46 // Determine whether the following line will start a
47 if (LineStr.find("*** Dumping AST Record Layout") != StringRef::npos) {
48 // Flush the last type/layout, if there is one.
49 if (!CurrentType.empty())
50 Layouts[CurrentType] = CurrentLayout;
51 CurrentLayout = Layout();
52
53 ExpectingType = true;
54 continue;
55 }
56
57 // If we're expecting a type, grab it.
58 if (ExpectingType) {
59 ExpectingType = false;
60
61 StringRef::size_type Pos;
62 if ((Pos = LineStr.find("struct ")) != StringRef::npos)
63 LineStr = LineStr.substr(Pos + strlen("struct "));
64 else if ((Pos = LineStr.find("class ")) != StringRef::npos)
65 LineStr = LineStr.substr(Pos + strlen("class "));
66 else if ((Pos = LineStr.find("union ")) != StringRef::npos)
67 LineStr = LineStr.substr(Pos + strlen("union "));
68 else
69 continue;
70
71 // Find the name of the type.
72 CurrentType = parseName(LineStr);
73 CurrentLayout = Layout();
74 continue;
75 }
76
77 // Check for the size of the type.
78 StringRef::size_type Pos = LineStr.find(" Size:");
79 if (Pos != StringRef::npos) {
80 // Skip past the " Size:" prefix.
81 LineStr = LineStr.substr(Pos + strlen(" Size:"));
82
83 unsigned long long Size = 0;
84 (void)LineStr.getAsInteger(10, Size);
85 CurrentLayout.Size = Size;
86 continue;
87 }
88
89 // Check for the alignment of the type.
90 Pos = LineStr.find("Alignment:");
91 if (Pos != StringRef::npos) {
92 // Skip past the "Alignment:" prefix.
93 LineStr = LineStr.substr(Pos + strlen("Alignment:"));
94
95 unsigned long long Alignment = 0;
96 (void)LineStr.getAsInteger(10, Alignment);
97 CurrentLayout.Align = Alignment;
98 continue;
99 }
100
101 // Check for the size/alignment of the type.
102 Pos = LineStr.find("sizeof=");
103 if (Pos != StringRef::npos) {
104 /* Skip past the sizeof= prefix. */
105 LineStr = LineStr.substr(Pos + strlen("sizeof="));
106
107 // Parse size.
108 unsigned long long Size = 0;
109 (void)LineStr.getAsInteger(10, Size);
110 CurrentLayout.Size = Size;
111
112 Pos = LineStr.find("align=");
113 if (Pos != StringRef::npos) {
114 /* Skip past the align= prefix. */
115 LineStr = LineStr.substr(Pos + strlen("align="));
116
117 // Parse alignment.
118 unsigned long long Alignment = 0;
119 (void)LineStr.getAsInteger(10, Alignment);
120 CurrentLayout.Align = Alignment;
121 }
122
123 continue;
124 }
125
126 // Check for the field offsets of the type.
127 Pos = LineStr.find("FieldOffsets: [");
128 if (Pos == StringRef::npos)
129 continue;
130
131 LineStr = LineStr.substr(Pos + strlen("FieldOffsets: ["));
132 while (!LineStr.empty() && isDigit(LineStr[0])) {
133 // Parse this offset.
134 unsigned Idx = 1;
135 while (Idx < LineStr.size() && isDigit(LineStr[Idx]))
136 ++Idx;
137
138 unsigned long long Offset = 0;
139 (void)LineStr.substr(0, Idx).getAsInteger(10, Offset);
140
141 CurrentLayout.FieldOffsets.push_back(Offset);
142
143 // Skip over this offset, the following comma, and any spaces.
144 LineStr = LineStr.substr(Idx + 1);
145 while (!LineStr.empty() && isWhitespace(LineStr[0]))
146 LineStr = LineStr.substr(1);
147 }
148 }
149
150 // Flush the last type/layout, if there is one.
151 if (!CurrentType.empty())
152 Layouts[CurrentType] = CurrentLayout;
153 }
154
155 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)156 LayoutOverrideSource::layoutRecordType(const RecordDecl *Record,
157 uint64_t &Size, uint64_t &Alignment,
158 llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,
159 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,
160 llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets)
161 {
162 // We can't override unnamed declarations.
163 if (!Record->getIdentifier())
164 return false;
165
166 // Check whether we have a layout for this record.
167 llvm::StringMap<Layout>::iterator Known = Layouts.find(Record->getName());
168 if (Known == Layouts.end())
169 return false;
170
171 // Provide field layouts.
172 unsigned NumFields = 0;
173 for (RecordDecl::field_iterator F = Record->field_begin(),
174 FEnd = Record->field_end();
175 F != FEnd; ++F, ++NumFields) {
176 if (NumFields >= Known->second.FieldOffsets.size())
177 continue;
178
179 FieldOffsets[*F] = Known->second.FieldOffsets[NumFields];
180 }
181
182 // Wrong number of fields.
183 if (NumFields != Known->second.FieldOffsets.size())
184 return false;
185
186 Size = Known->second.Size;
187 Alignment = Known->second.Align;
188 return true;
189 }
190
dump()191 void LayoutOverrideSource::dump() {
192 raw_ostream &OS = llvm::errs();
193 for (llvm::StringMap<Layout>::iterator L = Layouts.begin(),
194 LEnd = Layouts.end();
195 L != LEnd; ++L) {
196 OS << "Type: blah " << L->first() << '\n';
197 OS << " Size:" << L->second.Size << '\n';
198 OS << " Alignment:" << L->second.Align << '\n';
199 OS << " FieldOffsets: [";
200 for (unsigned I = 0, N = L->second.FieldOffsets.size(); I != N; ++I) {
201 if (I)
202 OS << ", ";
203 OS << L->second.FieldOffsets[I];
204 }
205 OS << "]\n";
206 }
207 }
208
209