1 files changed, 67 insertions, 0 deletions
diff --git a/ELF/Memory.h b/ELF/Memory.h
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index 000000000000..e5a04ed1e5a8
--- /dev/null
+++ b/ELF/Memory.h
@@ -0,0 +1,67 @@
+//===- Memory.h -------------------------------------------------*- C++ -*-===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines arena allocators.
+//
+// Almost all large objects, such as files, sections or symbols, are
+// used for the entire lifetime of the linker once they are created.
+// This usage characteristic makes arena allocator an attractive choice
+// where the entire linker is one arena. With an arena, newly created
+// objects belong to the arena and freed all at once when everything is done.
+// Arena allocators are efficient and easy to understand.
+// Most objects are allocated using the arena allocators defined by this file.
+//
+// If you edit this file, please edit COFF/Memory.h too.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_ELF_MEMORY_H
+#define LLD_ELF_MEMORY_H
+
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/StringSaver.h"
+#include <vector>
+
+namespace lld {
+namespace elf {
+
+// Use this arena if your object doesn't have a destructor.
+extern llvm::BumpPtrAllocator BAlloc;
+extern llvm::StringSaver Saver;
+
+// These two classes are hack to keep track of all
+// SpecificBumpPtrAllocator instances.
+struct SpecificAllocBase {
+  SpecificAllocBase() { Instances.push_back(this); }
+  virtual ~SpecificAllocBase() = default;
+  virtual void reset() = 0;
+  static std::vector<SpecificAllocBase *> Instances;
+};
+
+template <class T> struct SpecificAlloc : public SpecificAllocBase {
+  void reset() override { Alloc.DestroyAll(); }
+  llvm::SpecificBumpPtrAllocator<T> Alloc;
+};
+
+// Use this arena if your object has a destructor.
+// Your destructor will be invoked from freeArena().
+template <typename T, typename... U> T *make(U &&... Args) {
+  static SpecificAlloc<T> Alloc;
+  return new (Alloc.Alloc.Allocate()) T(std::forward<U>(Args)...);
+}
+
+inline void freeArena() {
+  for (SpecificAllocBase *Alloc : SpecificAllocBase::Instances)
+    Alloc->reset();
+  BAlloc.Reset();
+}
+}
+}
+
+#endif