lld/MachO/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_MACHO_INPUT_FILES_H
  10 #define LLD_MACHO_INPUT_FILES_H
  11
  12 #include "MachOStructs.h"
  13 #include "Target.h"
  14
  15 #include "lld/Common/DWARF.h"
  16 #include "lld/Common/LLVM.h"
  17 #include "lld/Common/Memory.h"
  18 #include "llvm/ADT/CachedHashString.h"
  19 #include "llvm/ADT/DenseSet.h"
  20 #include "llvm/ADT/SetVector.h"
  21 #include "llvm/BinaryFormat/MachO.h"
  22 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
  23 #include "llvm/Object/Archive.h"
  24 #include "llvm/Support/MemoryBuffer.h"
  25 #include "llvm/Support/Threading.h"
  26 #include "llvm/TextAPI/TextAPIReader.h"
  27
  28 #include <vector>
  29
  30 namespace llvm {
  31 namespace lto {
  32 class InputFile;
  33 } // namespace lto
  34 namespace MachO {
  35 class InterfaceFile;
  36 } // namespace MachO
  37 class TarWriter;
  38 } // namespace llvm
  39
  40 namespace lld {
  41 namespace macho {
  42
  43 struct PlatformInfo;
  44 class ConcatInputSection;
  45 class Symbol;
  46 class Defined;
  47 struct Reloc;
  48 enum class RefState : uint8_t;
  49
  50 // If --reproduce option is given, all input files are written
  51 // to this tar archive.
  52 extern std::unique_ptr<llvm::TarWriter> tar;
  53
  54 // If .subsections_via_symbols is set, each InputSection will be split along
  55 // symbol boundaries. The field offset represents the offset of the subsection
  56 // from the start of the original pre-split InputSection.
  57 struct Subsection {
  58   uint64_t offset = 0;
  59   InputSection *isec = nullptr;
  60 };
  61
  62 using Subsections = std::vector<Subsection>;
  63 class InputFile;
  64
  65 class Section {
  66 public:
  67   InputFile *file;
  68   StringRef segname;
  69   StringRef name;
  70   uint32_t flags;
  71   uint64_t addr;
  72   Subsections subsections;
  73
  74   Section(InputFile *file, StringRef segname, StringRef name, uint32_t flags,
  75           uint64_t addr)
  76       : file(file), segname(segname), name(name), flags(flags), addr(addr) {}
  77   // Ensure pointers to Sections are never invalidated.
  78   Section(const Section &) = delete;
  79   Section &operator=(const Section &) = delete;
  80   Section(Section &&) = delete;
  81   Section &operator=(Section &&) = delete;
  82
  83 private:
  84   // Whether we have already split this section into individual subsections.
  85   // For sections that cannot be split (e.g. literal sections), this is always
  86   // false.
  87   bool doneSplitting = false;
  88   friend class ObjFile;
  89 };
  90
  91 // Represents a call graph profile edge.
  92 struct CallGraphEntry {
  93   // The index of the caller in the symbol table.
  94   uint32_t fromIndex;
  95   // The index of the callee in the symbol table.
  96   uint32_t toIndex;
  97   // Number of calls from callee to caller in the profile.
  98   uint64_t count;
  99
 100   CallGraphEntry(uint32_t fromIndex, uint32_t toIndex, uint64_t count)
 101       : fromIndex(fromIndex), toIndex(toIndex), count(count) {}
 102 };
 103
 104 class InputFile {
 105 public:
 106   enum Kind {
 107     ObjKind,
 108     OpaqueKind,
 109     DylibKind,
 110     ArchiveKind,
 111     BitcodeKind,
 112   };
 113
 114   virtual ~InputFile() = default;
 115   Kind kind() const { return fileKind; }
 116   StringRef getName() const { return name; }
 117   static void resetIdCount() { idCount = 0; }
 118
 119   MemoryBufferRef mb;
 120
 121   std::vector<Symbol *> symbols;
 122   std::vector<Section *> sections;
 123   ArrayRef<uint8_t> objCImageInfo;
 124
 125   // If not empty, this stores the name of the archive containing this file.
 126   // We use this string for creating error messages.
 127   std::string archiveName;
 128
 129   // Provides an easy way to sort InputFiles deterministically.
 130   const int id;
 131
 132   // True if this is a lazy ObjFile or BitcodeFile.
 133   bool lazy = false;
 134
 135 protected:
 136   InputFile(Kind kind, MemoryBufferRef mb, bool lazy = false)
 137       : mb(mb), id(idCount++), lazy(lazy), fileKind(kind),
 138         name(mb.getBufferIdentifier()) {}
 139
 140   InputFile(Kind, const llvm::MachO::InterfaceFile &);
 141
 142 private:
 143   const Kind fileKind;
 144   const StringRef name;
 145
 146   static int idCount;
 147 };
 148
 149 struct FDE {
 150   uint32_t funcLength;
 151   Symbol *personality;
 152   InputSection *lsda;
 153 };
 154
 155 // .o file
 156 class ObjFile final : public InputFile {
 157 public:
 158   ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName,
 159           bool lazy = false, bool forceHidden = false);
 160   ArrayRef<llvm::MachO::data_in_code_entry> getDataInCode() const;
 161   template <class LP> void parse();
 162
 163   static bool classof(const InputFile *f) { return f->kind() == ObjKind; }
 164
 165   std::string sourceFile() const;
 166   // Parses line table information for diagnostics. compileUnit should be used
 167   // for other purposes.
 168   lld::DWARFCache *getDwarf();
 169
 170   llvm::DWARFUnit *compileUnit = nullptr;
 171   std::unique_ptr<lld::DWARFCache> dwarfCache;
 172   Section *addrSigSection = nullptr;
 173   const uint32_t modTime;
 174   bool forceHidden;
 175   std::vector<ConcatInputSection *> debugSections;
 176   std::vector<CallGraphEntry> callGraph;
 177   llvm::DenseMap<ConcatInputSection *, FDE> fdes;
 178   std::vector<OptimizationHint> optimizationHints;
 179
 180 private:
 181   llvm::once_flag initDwarf;
 182   template <class LP> void parseLazy();
 183   template <class SectionHeader> void parseSections(ArrayRef<SectionHeader>);
 184   template <class LP>
 185   void parseSymbols(ArrayRef<typename LP::section> sectionHeaders,
 186                     ArrayRef<typename LP::nlist> nList, const char *strtab,
 187                     bool subsectionsViaSymbols);
 188   template <class NList>
 189   Symbol *parseNonSectionSymbol(const NList &sym, StringRef name);
 190   template <class SectionHeader>
 191   void parseRelocations(ArrayRef<SectionHeader> sectionHeaders,
 192                         const SectionHeader &, Section &);
 193   void parseDebugInfo();
 194   void parseOptimizationHints(ArrayRef<uint8_t> data);
 195   void splitEhFrames(ArrayRef<uint8_t> dataArr, Section &ehFrameSection);
 196   void registerCompactUnwind(Section &compactUnwindSection);
 197   void registerEhFrames(Section &ehFrameSection);
 198 };
 199
 200 // command-line -sectcreate file
 201 class OpaqueFile final : public InputFile {
 202 public:
 203   OpaqueFile(MemoryBufferRef mb, StringRef segName, StringRef sectName);
 204   static bool classof(const InputFile *f) { return f->kind() == OpaqueKind; }
 205 };
 206
 207 // .dylib or .tbd file
 208 class DylibFile final : public InputFile {
 209 public:
 210   // Mach-O dylibs can re-export other dylibs as sub-libraries, meaning that the
 211   // symbols in those sub-libraries will be available under the umbrella
 212   // library's namespace. Those sub-libraries can also have their own
 213   // re-exports. When loading a re-exported dylib, `umbrella` should be set to
 214   // the root dylib to ensure symbols in the child library are correctly bound
 215   // to the root. On the other hand, if a dylib is being directly loaded
 216   // (through an -lfoo flag), then `umbrella` should be a nullptr.
 217   explicit DylibFile(MemoryBufferRef mb, DylibFile *umbrella,
 218                      bool isBundleLoader, bool explicitlyLinked);
 219   explicit DylibFile(const llvm::MachO::InterfaceFile &interface,
 220                      DylibFile *umbrella, bool isBundleLoader,
 221                      bool explicitlyLinked);
 222   explicit DylibFile(DylibFile *umbrella);
 223
 224   void parseLoadCommands(MemoryBufferRef mb);
 225   void parseReexports(const llvm::MachO::InterfaceFile &interface);
 226   bool isReferenced() const { return numReferencedSymbols > 0; }
 227   bool isExplicitlyLinked() const;
 228   void setExplicitlyLinked() { explicitlyLinked = true; }
 229
 230   static bool classof(const InputFile *f) { return f->kind() == DylibKind; }
 231
 232   StringRef installName;
 233   DylibFile *exportingFile = nullptr;
 234   DylibFile *umbrella;
 235   SmallVector<StringRef, 2> rpaths;
 236   uint32_t compatibilityVersion = 0;
 237   uint32_t currentVersion = 0;
 238   int64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel
 239   unsigned numReferencedSymbols = 0;
 240   RefState refState;
 241   bool reexport = false;
 242   bool forceNeeded = false;
 243   bool forceWeakImport = false;
 244   bool deadStrippable = false;
 245
 246 private:
 247   bool explicitlyLinked = false; // Access via isExplicitlyLinked().
 248
 249 public:
 250   // An executable can be used as a bundle loader that will load the output
 251   // file being linked, and that contains symbols referenced, but not
 252   // implemented in the bundle. When used like this, it is very similar
 253   // to a dylib, so we've used the same class to represent it.
 254   bool isBundleLoader;
 255
 256   // Synthetic Dylib objects created by $ld$previous symbols in this dylib.
 257   // Usually empty. These synthetic dylibs won't have synthetic dylibs
 258   // themselves.
 259   SmallVector<DylibFile *, 2> extraDylibs;
 260
 261 private:
 262   DylibFile *getSyntheticDylib(StringRef installName, uint32_t currentVersion,
 263                                uint32_t compatVersion);
 264
 265   bool handleLDSymbol(StringRef originalName);
 266   void handleLDPreviousSymbol(StringRef name, StringRef originalName);
 267   void handleLDInstallNameSymbol(StringRef name, StringRef originalName);
 268   void handleLDHideSymbol(StringRef name, StringRef originalName);
 269   void checkAppExtensionSafety(bool dylibIsAppExtensionSafe) const;
 270   void parseExportedSymbols(uint32_t offset, uint32_t size);
 271
 272   llvm::DenseSet<llvm::CachedHashStringRef> hiddenSymbols;
 273 };
 274
 275 // .a file
 276 class ArchiveFile final : public InputFile {
 277 public:
 278   explicit ArchiveFile(std::unique_ptr<llvm::object::Archive> &&file,
 279                        bool forceHidden);
 280   void addLazySymbols();
 281   void fetch(const llvm::object::Archive::Symbol &);
 282   // LLD normally doesn't use Error for error-handling, but the underlying
 283   // Archive library does, so this is the cleanest way to wrap it.
 284   Error fetch(const llvm::object::Archive::Child &, StringRef reason);
 285   const llvm::object::Archive &getArchive() const { return *file; };
 286   static bool classof(const InputFile *f) { return f->kind() == ArchiveKind; }
 287
 288 private:
 289   std::unique_ptr<llvm::object::Archive> file;
 290   // Keep track of children fetched from the archive by tracking
 291   // which address offsets have been fetched already.
 292   llvm::DenseSet<uint64_t> seen;
 293   // Load all symbols with hidden visibility (-load_hidden).
 294   bool forceHidden;
 295 };
 296
 297 class BitcodeFile final : public InputFile {
 298 public:
 299   explicit BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
 300                        uint64_t offsetInArchive, bool lazy = false,
 301                        bool forceHidden = false);
 302   static bool classof(const InputFile *f) { return f->kind() == BitcodeKind; }
 303   void parse();
 304
 305   std::unique_ptr<llvm::lto::InputFile> obj;
 306   bool forceHidden;
 307
 308 private:
 309   void parseLazy();
 310 };
 311
 312 extern llvm::SetVector<InputFile *> inputFiles;
 313 extern llvm::DenseMap<llvm::CachedHashStringRef, MemoryBufferRef> cachedReads;
 314
 315 llvm::Optional<MemoryBufferRef> readFile(StringRef path);
 316
 317 void extract(InputFile &file, StringRef reason);
 318
 319 namespace detail {
 320
 321 template <class CommandType, class... Types>
 322 std::vector<const CommandType *>
 323 findCommands(const void *anyHdr, size_t maxCommands, Types... types) {
 324   std::vector<const CommandType *> cmds;
 325   std::initializer_list<uint32_t> typesList{types...};
 326   const auto *hdr = reinterpret_cast<const llvm::MachO::mach_header *>(anyHdr);
 327   const uint8_t *p =
 328       reinterpret_cast<const uint8_t *>(hdr) + target->headerSize;
 329   for (uint32_t i = 0, n = hdr->ncmds; i < n; ++i) {
 330     auto *cmd = reinterpret_cast<const CommandType *>(p);
 331     if (llvm::is_contained(typesList, cmd->cmd)) {
 332       cmds.push_back(cmd);
 333       if (cmds.size() == maxCommands)
 334         return cmds;
 335     }
 336     p += cmd->cmdsize;
 337   }
 338   return cmds;
 339 }
 340
 341 } // namespace detail
 342
 343 // anyHdr should be a pointer to either mach_header or mach_header_64
 344 template <class CommandType = llvm::MachO::load_command, class... Types>
 345 const CommandType *findCommand(const void *anyHdr, Types... types) {
 346   std::vector<const CommandType *> cmds =
 347       detail::findCommands<CommandType>(anyHdr, 1, types...);
 348   return cmds.size() ? cmds[0] : nullptr;
 349 }
 350
 351 template <class CommandType = llvm::MachO::load_command, class... Types>
 352 std::vector<const CommandType *> findCommands(const void *anyHdr,
 353                                               Types... types) {
 354   return detail::findCommands<CommandType>(anyHdr, 0, types...);
 355 }
 356
 357 } // namespace macho
 358
 359 std::string toString(const macho::InputFile *file);
 360 std::string toString(const macho::Section &);
 361 } // namespace lld
 362
 363 #endif