xref: /freebsd/contrib/llvm-project/lld/COFF/InputFiles.h (revision e6bfd18d21b225af6a0ed67ceeaf1293b7b9eba5)
1 //===- InputFiles.h ---------------------------------------------*- 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 #ifndef LLD_COFF_INPUT_FILES_H
10 #define LLD_COFF_INPUT_FILES_H
11 
12 #include "Config.h"
13 #include "lld/Common/LLVM.h"
14 #include "llvm/ADT/ArrayRef.h"
15 #include "llvm/ADT/DenseMap.h"
16 #include "llvm/ADT/DenseSet.h"
17 #include "llvm/ADT/StringSet.h"
18 #include "llvm/BinaryFormat/Magic.h"
19 #include "llvm/Object/Archive.h"
20 #include "llvm/Object/COFF.h"
21 #include "llvm/Support/StringSaver.h"
22 #include <memory>
23 #include <set>
24 #include <vector>
25 
26 namespace llvm {
27 struct DILineInfo;
28 namespace pdb {
29 class DbiModuleDescriptorBuilder;
30 class NativeSession;
31 }
32 namespace lto {
33 class InputFile;
34 }
35 }
36 
37 namespace lld {
38 class DWARFCache;
39 
40 namespace coff {
41 class COFFLinkerContext;
42 
43 std::vector<MemoryBufferRef> getArchiveMembers(llvm::object::Archive *file);
44 
45 using llvm::COFF::IMAGE_FILE_MACHINE_UNKNOWN;
46 using llvm::COFF::MachineTypes;
47 using llvm::object::Archive;
48 using llvm::object::COFFObjectFile;
49 using llvm::object::COFFSymbolRef;
50 using llvm::object::coff_import_header;
51 using llvm::object::coff_section;
52 
53 class Chunk;
54 class Defined;
55 class DefinedImportData;
56 class DefinedImportThunk;
57 class DefinedRegular;
58 class SectionChunk;
59 class Symbol;
60 class Undefined;
61 class TpiSource;
62 
63 // The root class of input files.
64 class InputFile {
65 public:
66   enum Kind {
67     ArchiveKind,
68     ObjectKind,
69     LazyObjectKind,
70     PDBKind,
71     ImportKind,
72     BitcodeKind,
73     DLLKind
74   };
75   Kind kind() const { return fileKind; }
76   virtual ~InputFile() {}
77 
78   // Returns the filename.
79   StringRef getName() const { return mb.getBufferIdentifier(); }
80 
81   // Reads a file (the constructor doesn't do that).
82   virtual void parse() = 0;
83 
84   // Returns the CPU type this file was compiled to.
85   virtual MachineTypes getMachineType() { return IMAGE_FILE_MACHINE_UNKNOWN; }
86 
87   MemoryBufferRef mb;
88 
89   // An archive file name if this file is created from an archive.
90   StringRef parentName;
91 
92   // Returns .drectve section contents if exist.
93   StringRef getDirectives() { return directives; }
94 
95   COFFLinkerContext &ctx;
96 
97 protected:
98   InputFile(COFFLinkerContext &c, Kind k, MemoryBufferRef m, bool lazy = false)
99       : mb(m), ctx(c), fileKind(k), lazy(lazy) {}
100 
101   StringRef directives;
102 
103 private:
104   const Kind fileKind;
105 
106 public:
107   // True if this is a lazy ObjFile or BitcodeFile.
108   bool lazy = false;
109 };
110 
111 // .lib or .a file.
112 class ArchiveFile : public InputFile {
113 public:
114   explicit ArchiveFile(COFFLinkerContext &ctx, MemoryBufferRef m);
115   static bool classof(const InputFile *f) { return f->kind() == ArchiveKind; }
116   void parse() override;
117 
118   // Enqueues an archive member load for the given symbol. If we've already
119   // enqueued a load for the same archive member, this function does nothing,
120   // which ensures that we don't load the same member more than once.
121   void addMember(const Archive::Symbol &sym);
122 
123 private:
124   std::unique_ptr<Archive> file;
125   llvm::DenseSet<uint64_t> seen;
126 };
127 
128 // .obj or .o file. This may be a member of an archive file.
129 class ObjFile : public InputFile {
130 public:
131   explicit ObjFile(COFFLinkerContext &ctx, MemoryBufferRef m, bool lazy = false)
132       : InputFile(ctx, ObjectKind, m, lazy) {}
133   static bool classof(const InputFile *f) { return f->kind() == ObjectKind; }
134   void parse() override;
135   void parseLazy();
136   MachineTypes getMachineType() override;
137   ArrayRef<Chunk *> getChunks() { return chunks; }
138   ArrayRef<SectionChunk *> getDebugChunks() { return debugChunks; }
139   ArrayRef<SectionChunk *> getSXDataChunks() { return sxDataChunks; }
140   ArrayRef<SectionChunk *> getGuardFidChunks() { return guardFidChunks; }
141   ArrayRef<SectionChunk *> getGuardIATChunks() { return guardIATChunks; }
142   ArrayRef<SectionChunk *> getGuardLJmpChunks() { return guardLJmpChunks; }
143   ArrayRef<SectionChunk *> getGuardEHContChunks() { return guardEHContChunks; }
144   ArrayRef<Symbol *> getSymbols() { return symbols; }
145 
146   MutableArrayRef<Symbol *> getMutableSymbols() { return symbols; }
147 
148   ArrayRef<uint8_t> getDebugSection(StringRef secName);
149 
150   // Returns a Symbol object for the symbolIndex'th symbol in the
151   // underlying object file.
152   Symbol *getSymbol(uint32_t symbolIndex) {
153     return symbols[symbolIndex];
154   }
155 
156   // Returns the underlying COFF file.
157   COFFObjectFile *getCOFFObj() { return coffObj.get(); }
158 
159   // Add a symbol for a range extension thunk. Return the new symbol table
160   // index. This index can be used to modify a relocation.
161   uint32_t addRangeThunkSymbol(Symbol *thunk) {
162     symbols.push_back(thunk);
163     return symbols.size() - 1;
164   }
165 
166   void includeResourceChunks();
167 
168   bool isResourceObjFile() const { return !resourceChunks.empty(); }
169 
170   // Flags in the absolute @feat.00 symbol if it is present. These usually
171   // indicate if an object was compiled with certain security features enabled
172   // like stack guard, safeseh, /guard:cf, or other things.
173   uint32_t feat00Flags = 0;
174 
175   // True if this object file is compatible with SEH.  COFF-specific and
176   // x86-only. COFF spec 5.10.1. The .sxdata section.
177   bool hasSafeSEH() { return feat00Flags & 0x1; }
178 
179   // True if this file was compiled with /guard:cf.
180   bool hasGuardCF() { return feat00Flags & 0x4800; }
181 
182   // Pointer to the PDB module descriptor builder. Various debug info records
183   // will reference object files by "module index", which is here. Things like
184   // source files and section contributions are also recorded here. Will be null
185   // if we are not producing a PDB.
186   llvm::pdb::DbiModuleDescriptorBuilder *moduleDBI = nullptr;
187 
188   const coff_section *addrsigSec = nullptr;
189 
190   const coff_section *callgraphSec = nullptr;
191 
192   // When using Microsoft precompiled headers, this is the PCH's key.
193   // The same key is used by both the precompiled object, and objects using the
194   // precompiled object. Any difference indicates out-of-date objects.
195   llvm::Optional<uint32_t> pchSignature;
196 
197   // Whether this file was compiled with /hotpatch.
198   bool hotPatchable = false;
199 
200   // Whether the object was already merged into the final PDB.
201   bool mergedIntoPDB = false;
202 
203   // If the OBJ has a .debug$T stream, this tells how it will be handled.
204   TpiSource *debugTypesObj = nullptr;
205 
206   // The .debug$P or .debug$T section data if present. Empty otherwise.
207   ArrayRef<uint8_t> debugTypes;
208 
209   llvm::Optional<std::pair<StringRef, uint32_t>>
210   getVariableLocation(StringRef var);
211 
212   llvm::Optional<llvm::DILineInfo> getDILineInfo(uint32_t offset,
213                                                  uint32_t sectionIndex);
214 
215 private:
216   const coff_section* getSection(uint32_t i);
217   const coff_section *getSection(COFFSymbolRef sym) {
218     return getSection(sym.getSectionNumber());
219   }
220 
221   void enqueuePdbFile(StringRef path, ObjFile *fromFile);
222 
223   void initializeChunks();
224   void initializeSymbols();
225   void initializeFlags();
226   void initializeDependencies();
227 
228   SectionChunk *
229   readSection(uint32_t sectionNumber,
230               const llvm::object::coff_aux_section_definition *def,
231               StringRef leaderName);
232 
233   void readAssociativeDefinition(
234       COFFSymbolRef coffSym,
235       const llvm::object::coff_aux_section_definition *def);
236 
237   void readAssociativeDefinition(
238       COFFSymbolRef coffSym,
239       const llvm::object::coff_aux_section_definition *def,
240       uint32_t parentSection);
241 
242   void recordPrevailingSymbolForMingw(
243       COFFSymbolRef coffSym,
244       llvm::DenseMap<StringRef, uint32_t> &prevailingSectionMap);
245 
246   void maybeAssociateSEHForMingw(
247       COFFSymbolRef sym, const llvm::object::coff_aux_section_definition *def,
248       const llvm::DenseMap<StringRef, uint32_t> &prevailingSectionMap);
249 
250   // Given a new symbol Sym with comdat selection Selection, if the new
251   // symbol is not (yet) Prevailing and the existing comdat leader set to
252   // Leader, emits a diagnostic if the new symbol and its selection doesn't
253   // match the existing symbol and its selection. If either old or new
254   // symbol have selection IMAGE_COMDAT_SELECT_LARGEST, Sym might replace
255   // the existing leader. In that case, Prevailing is set to true.
256   void
257   handleComdatSelection(COFFSymbolRef sym, llvm::COFF::COMDATType &selection,
258                         bool &prevailing, DefinedRegular *leader,
259                         const llvm::object::coff_aux_section_definition *def);
260 
261   llvm::Optional<Symbol *>
262   createDefined(COFFSymbolRef sym,
263                 std::vector<const llvm::object::coff_aux_section_definition *>
264                     &comdatDefs,
265                 bool &prevailingComdat);
266   Symbol *createRegular(COFFSymbolRef sym);
267   Symbol *createUndefined(COFFSymbolRef sym);
268 
269   std::unique_ptr<COFFObjectFile> coffObj;
270 
271   // List of all chunks defined by this file. This includes both section
272   // chunks and non-section chunks for common symbols.
273   std::vector<Chunk *> chunks;
274 
275   std::vector<SectionChunk *> resourceChunks;
276 
277   // CodeView debug info sections.
278   std::vector<SectionChunk *> debugChunks;
279 
280   // Chunks containing symbol table indices of exception handlers. Only used for
281   // 32-bit x86.
282   std::vector<SectionChunk *> sxDataChunks;
283 
284   // Chunks containing symbol table indices of address taken symbols, address
285   // taken IAT entries, longjmp and ehcont targets. These are not linked into
286   // the final binary when /guard:cf is set.
287   std::vector<SectionChunk *> guardFidChunks;
288   std::vector<SectionChunk *> guardIATChunks;
289   std::vector<SectionChunk *> guardLJmpChunks;
290   std::vector<SectionChunk *> guardEHContChunks;
291 
292   // This vector contains a list of all symbols defined or referenced by this
293   // file. They are indexed such that you can get a Symbol by symbol
294   // index. Nonexistent indices (which are occupied by auxiliary
295   // symbols in the real symbol table) are filled with null pointers.
296   std::vector<Symbol *> symbols;
297 
298   // This vector contains the same chunks as Chunks, but they are
299   // indexed such that you can get a SectionChunk by section index.
300   // Nonexistent section indices are filled with null pointers.
301   // (Because section number is 1-based, the first slot is always a
302   // null pointer.) This vector is only valid during initialization.
303   std::vector<SectionChunk *> sparseChunks;
304 
305   DWARFCache *dwarf = nullptr;
306 };
307 
308 // This is a PDB type server dependency, that is not a input file per se, but
309 // needs to be treated like one. Such files are discovered from the debug type
310 // stream.
311 class PDBInputFile : public InputFile {
312 public:
313   explicit PDBInputFile(COFFLinkerContext &ctx, MemoryBufferRef m);
314   ~PDBInputFile();
315   static bool classof(const InputFile *f) { return f->kind() == PDBKind; }
316   void parse() override;
317 
318   static PDBInputFile *findFromRecordPath(const COFFLinkerContext &ctx,
319                                           StringRef path, ObjFile *fromFile);
320 
321   // Record possible errors while opening the PDB file
322   llvm::Optional<Error> loadErr;
323 
324   // This is the actual interface to the PDB (if it was opened successfully)
325   std::unique_ptr<llvm::pdb::NativeSession> session;
326 
327   // If the PDB has a .debug$T stream, this tells how it will be handled.
328   TpiSource *debugTypesObj = nullptr;
329 };
330 
331 // This type represents import library members that contain DLL names
332 // and symbols exported from the DLLs. See Microsoft PE/COFF spec. 7
333 // for details about the format.
334 class ImportFile : public InputFile {
335 public:
336   explicit ImportFile(COFFLinkerContext &ctx, MemoryBufferRef m)
337       : InputFile(ctx, ImportKind, m) {}
338 
339   static bool classof(const InputFile *f) { return f->kind() == ImportKind; }
340 
341   Symbol *impSym = nullptr;
342   Symbol *thunkSym = nullptr;
343   std::string dllName;
344 
345 private:
346   void parse() override;
347 
348 public:
349   StringRef externalName;
350   const coff_import_header *hdr;
351   Chunk *location = nullptr;
352 
353   // We want to eliminate dllimported symbols if no one actually refers to them.
354   // These "Live" bits are used to keep track of which import library members
355   // are actually in use.
356   //
357   // If the Live bit is turned off by MarkLive, Writer will ignore dllimported
358   // symbols provided by this import library member. We also track whether the
359   // imported symbol is used separately from whether the thunk is used in order
360   // to avoid creating unnecessary thunks.
361   bool live = !config->doGC;
362   bool thunkLive = !config->doGC;
363 };
364 
365 // Used for LTO.
366 class BitcodeFile : public InputFile {
367 public:
368   explicit BitcodeFile(COFFLinkerContext &ctx, MemoryBufferRef mb,
369                        StringRef archiveName, uint64_t offsetInArchive,
370                        bool lazy);
371   ~BitcodeFile();
372   static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }
373   ArrayRef<Symbol *> getSymbols() { return symbols; }
374   MachineTypes getMachineType() override;
375   void parseLazy();
376   std::unique_ptr<llvm::lto::InputFile> obj;
377 
378 private:
379   void parse() override;
380 
381   std::vector<Symbol *> symbols;
382 };
383 
384 // .dll file. MinGW only.
385 class DLLFile : public InputFile {
386 public:
387   explicit DLLFile(COFFLinkerContext &ctx, MemoryBufferRef m)
388       : InputFile(ctx, DLLKind, m) {}
389   static bool classof(const InputFile *f) { return f->kind() == DLLKind; }
390   void parse() override;
391   MachineTypes getMachineType() override;
392 
393   struct Symbol {
394     StringRef dllName;
395     StringRef symbolName;
396     llvm::COFF::ImportNameType nameType;
397     llvm::COFF::ImportType importType;
398   };
399 
400   void makeImport(Symbol *s);
401 
402 private:
403   std::unique_ptr<COFFObjectFile> coffObj;
404   llvm::StringSet<> seen;
405 };
406 
407 inline bool isBitcode(MemoryBufferRef mb) {
408   return identify_magic(mb.getBuffer()) == llvm::file_magic::bitcode;
409 }
410 
411 std::string replaceThinLTOSuffix(StringRef path);
412 } // namespace coff
413 
414 std::string toString(const coff::InputFile *file);
415 } // namespace lld
416 
417 #endif
418