lld/COFF/InputFiles.h

   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