1 files changed, 117 insertions, 0 deletions
diff --git a/include/lld/Core/SymbolTable.h b/include/lld/Core/SymbolTable.h
new file mode 100644
index 000000000000..683ed65e3635
--- /dev/null
+++ b/include/lld/Core/SymbolTable.h
@@ -0,0 +1,117 @@
+//===- Core/SymbolTable.h - Main Symbol Table -----------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_CORE_SYMBOL_TABLE_H
+#define LLD_CORE_SYMBOL_TABLE_H
+
+#include "lld/Core/LLVM.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/StringExtras.h"
+#include <cstring>
+#include <map>
+#include <vector>
+
+namespace lld {
+
+class AbsoluteAtom;
+class Atom;
+class DefinedAtom;
+class LinkingContext;
+class ResolverOptions;
+class SharedLibraryAtom;
+class UndefinedAtom;
+
+/// \brief The SymbolTable class is responsible for coalescing atoms.
+///
+/// All atoms coalescable by-name or by-content should be added.
+/// The method replacement() can be used to find the replacement atom
+/// if an atom has been coalesced away.
+class SymbolTable {
+public:
+  explicit SymbolTable(LinkingContext &);
+
+  /// @brief add atom to symbol table
+  bool add(const DefinedAtom &);
+
+  /// @brief add atom to symbol table
+  bool add(const UndefinedAtom &);
+
+  /// @brief add atom to symbol table
+  bool add(const SharedLibraryAtom &);
+
+  /// @brief add atom to symbol table
+  bool add(const AbsoluteAtom &);
+
+  /// @brief checks if name is in symbol table and if so atom is not
+  ///        UndefinedAtom
+  bool isDefined(StringRef sym);
+
+  /// @brief returns atom in symbol table for specified name (or nullptr)
+  const Atom *findByName(StringRef sym);
+
+  /// @brief returns vector of remaining UndefinedAtoms
+  std::vector<const UndefinedAtom *> undefines();
+
+  /// returns vector of tentative definitions
+  std::vector<StringRef> tentativeDefinitions();
+
+  /// @brief add atom to replacement table
+  void addReplacement(const Atom *replaced, const Atom *replacement);
+
+  /// @brief if atom has been coalesced away, return replacement, else return atom
+  const Atom *replacement(const Atom *);
+
+  /// @brief if atom has been coalesced away, return true
+  bool isCoalescedAway(const Atom *);
+
+  /// @brief Find a group atom.
+  const Atom *findGroup(StringRef name);
+
+  /// @brief Add a group atom and returns true/false depending on whether the
+  /// previously existed.
+  bool addGroup(const DefinedAtom &da);
+
+private:
+  typedef llvm::DenseMap<const Atom *, const Atom *> AtomToAtom;
+
+  struct StringRefMappingInfo {
+    static StringRef getEmptyKey() { return StringRef(); }
+    static StringRef getTombstoneKey() { return StringRef(" ", 1); }
+    static unsigned getHashValue(StringRef const val) {
+      return llvm::HashString(val);
+    }
+    static bool isEqual(StringRef const lhs, StringRef const rhs) {
+      return lhs.equals(rhs);
+    }
+  };
+  typedef llvm::DenseMap<StringRef, const Atom *,
+                                           StringRefMappingInfo> NameToAtom;
+
+  struct AtomMappingInfo {
+    static const DefinedAtom * getEmptyKey() { return nullptr; }
+    static const DefinedAtom * getTombstoneKey() { return (DefinedAtom*)(-1); }
+    static unsigned getHashValue(const DefinedAtom * const Val);
+    static bool isEqual(const DefinedAtom * const LHS,
+                        const DefinedAtom * const RHS);
+  };
+  typedef llvm::DenseSet<const DefinedAtom*, AtomMappingInfo> AtomContentSet;
+
+  bool addByName(const Atom &);
+  bool addByContent(const DefinedAtom &);
+
+  LinkingContext &_context;
+  AtomToAtom _replacedAtoms;
+  NameToAtom _nameTable;
+  NameToAtom _groupTable;
+  AtomContentSet _contentTable;
+};
+
+} // namespace lld
+
+#endif // LLD_CORE_SYMBOL_TABLE_H