lld/COFF/SymbolTable.h

   1 //===- SymbolTable.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_SYMBOL_TABLE_H
  10 #define LLD_COFF_SYMBOL_TABLE_H
  11
  12 #include "InputFiles.h"
  13 #include "LTO.h"
  14 #include "llvm/ADT/CachedHashString.h"
  15 #include "llvm/ADT/DenseMap.h"
  16 #include "llvm/ADT/DenseMapInfo.h"
  17 #include "llvm/Support/raw_ostream.h"
  18
  19 namespace llvm {
  20 struct LTOCodeGenerator;
  21 }
  22
  23 namespace lld {
  24 namespace coff {
  25
  26 class Chunk;
  27 class CommonChunk;
  28 class Defined;
  29 class DefinedAbsolute;
  30 class DefinedRegular;
  31 class DefinedRelative;
  32 class LazyArchive;
  33 class SectionChunk;
  34 class Symbol;
  35
  36 // SymbolTable is a bucket of all known symbols, including defined,
  37 // undefined, or lazy symbols (the last one is symbols in archive
  38 // files whose archive members are not yet loaded).
  39 //
  40 // We put all symbols of all files to a SymbolTable, and the
  41 // SymbolTable selects the "best" symbols if there are name
  42 // conflicts. For example, obviously, a defined symbol is better than
  43 // an undefined symbol. Or, if there's a conflict between a lazy and a
  44 // undefined, it'll read an archive member to read a real definition
  45 // to replace the lazy symbol. The logic is implemented in the
  46 // add*() functions, which are called by input files as they are parsed.
  47 // There is one add* function per symbol type.
  48 class SymbolTable {
  49 public:
  50   void addFile(InputFile *file);
  51
  52   // Emit errors for symbols that cannot be resolved.
  53   void reportUnresolvable();
  54
  55   // Try to resolve any undefined symbols and update the symbol table
  56   // accordingly, then print an error message for any remaining undefined
  57   // symbols and warn about imported local symbols.
  58   void resolveRemainingUndefines();
  59
  60   // Load lazy objects that are needed for MinGW automatic import and for
  61   // doing stdcall fixups.
  62   void loadMinGWSymbols();
  63   bool handleMinGWAutomaticImport(Symbol *sym, StringRef name);
  64
  65   // Returns a list of chunks of selected symbols.
  66   std::vector<Chunk *> getChunks();
  67
  68   // Returns a symbol for a given name. Returns a nullptr if not found.
  69   Symbol *find(StringRef name);
  70   Symbol *findUnderscore(StringRef name);
  71
  72   // Occasionally we have to resolve an undefined symbol to its
  73   // mangled symbol. This function tries to find a mangled name
  74   // for U from the symbol table, and if found, set the symbol as
  75   // a weak alias for U.
  76   Symbol *findMangle(StringRef name);
  77
  78   // Build a set of COFF objects representing the combined contents of
  79   // BitcodeFiles and add them to the symbol table. Called after all files are
  80   // added and before the writer writes results to a file.
  81   void addCombinedLTOObjects();
  82
  83   // Creates an Undefined symbol for a given name.
  84   Symbol *addUndefined(StringRef name);
  85
  86   Symbol *addSynthetic(StringRef n, Chunk *c);
  87   Symbol *addAbsolute(StringRef n, uint64_t va);
  88
  89   Symbol *addUndefined(StringRef name, InputFile *f, bool isWeakAlias);
  90   void addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym);
  91   void addLazyObject(LazyObjFile *f, StringRef n);
  92   void addLazyDLLSymbol(DLLFile *f, DLLFile::Symbol *sym, StringRef n);
  93   Symbol *addAbsolute(StringRef n, COFFSymbolRef s);
  94   Symbol *addRegular(InputFile *f, StringRef n,
  95                      const llvm::object::coff_symbol_generic *s = nullptr,
  96                      SectionChunk *c = nullptr, uint32_t sectionOffset = 0);
  97   std::pair<DefinedRegular *, bool>
  98   addComdat(InputFile *f, StringRef n,
  99             const llvm::object::coff_symbol_generic *s = nullptr);
 100   Symbol *addCommon(InputFile *f, StringRef n, uint64_t size,
 101                     const llvm::object::coff_symbol_generic *s = nullptr,
 102                     CommonChunk *c = nullptr);
 103   Symbol *addImportData(StringRef n, ImportFile *f);
 104   Symbol *addImportThunk(StringRef name, DefinedImportData *s,
 105                          uint16_t machine);
 106   void addLibcall(StringRef name);
 107
 108   void reportDuplicate(Symbol *existing, InputFile *newFile,
 109                        SectionChunk *newSc = nullptr,
 110                        uint32_t newSectionOffset = 0);
 111
 112   // A list of chunks which to be added to .rdata.
 113   std::vector<Chunk *> localImportChunks;
 114
 115   // Iterates symbols in non-determinstic hash table order.
 116   template <typename T> void forEachSymbol(T callback) {
 117     for (auto &pair : symMap)
 118       callback(pair.second);
 119   }
 120
 121 private:
 122   /// Given a name without "__imp_" prefix, returns a defined symbol
 123   /// with the "__imp_" prefix, if it exists.
 124   Defined *impSymbol(StringRef name);
 125   /// Inserts symbol if not already present.
 126   std::pair<Symbol *, bool> insert(StringRef name);
 127   /// Same as insert(Name), but also sets isUsedInRegularObj.
 128   std::pair<Symbol *, bool> insert(StringRef name, InputFile *f);
 129
 130   std::vector<Symbol *> getSymsWithPrefix(StringRef prefix);
 131
 132   llvm::DenseMap<llvm::CachedHashStringRef, Symbol *> symMap;
 133   std::unique_ptr<BitcodeCompiler> lto;
 134 };
 135
 136 extern SymbolTable *symtab;
 137
 138 std::vector<std::string> getSymbolLocations(ObjFile *file, uint32_t symIndex);
 139
 140 StringRef ltrim1(StringRef s, const char *chars);
 141
 142 } // namespace coff
 143 } // namespace lld
 144
 145 #endif