Import LLVM, at r72732.

1 files changed, 116 insertions, 0 deletions

diff --git a/include/llvm/Support/Recycler.h b/include/llvm/Support/Recycler.h
new file mode 100644
index 0000000..2fa0365
--- /dev/null
+++ b/include/llvm/Support/Recycler.h
@@ -0,0 +1,116 @@
+//==- llvm/Support/Recycler.h - Recycling Allocator --------------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the Recycler class template.  See the doxygen comment for
+// Recycler for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_RECYCLER_H
+#define LLVM_SUPPORT_RECYCLER_H
+
+#include "llvm/ADT/ilist.h"
+#include "llvm/Support/AlignOf.h"
+#include <cassert>
+
+namespace llvm {
+
+/// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for
+/// printing statistics.
+///
+void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize);
+
+/// RecyclerStruct - Implementation detail for Recycler. This is a
+/// class that the recycler imposes on free'd memory to carve out
+/// next/prev pointers.
+struct RecyclerStruct {
+  RecyclerStruct *Prev, *Next;
+};
+
+template<>
+struct ilist_traits<RecyclerStruct> : ilist_default_traits<RecyclerStruct> {
+  static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; }
+  static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; }
+  static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; }
+  static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; }
+
+  mutable RecyclerStruct Sentinel;
+  RecyclerStruct *createSentinel() const {
+    return &Sentinel;
+  }
+  static void destroySentinel(RecyclerStruct *) {}
+
+  RecyclerStruct *provideInitialHead() const { return createSentinel(); }
+  RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); }
+  static void noteHead(RecyclerStruct*, RecyclerStruct*) {}
+
+  static void deleteNode(RecyclerStruct *) {
+    assert(0 && "Recycler's ilist_traits shouldn't see a deleteNode call!");
+  }
+};
+
+/// Recycler - This class manages a linked-list of deallocated nodes
+/// and facilitates reusing deallocated memory in place of allocating
+/// new memory.
+///
+template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment>
+class Recycler {
+  /// FreeList - Doubly-linked list of nodes that have deleted contents and
+  /// are not in active use.
+  ///
+  iplist<RecyclerStruct> FreeList;
+
+public:
+  ~Recycler() {
+    // If this fails, either the callee has lost track of some allocation,
+    // or the callee isn't tracking allocations and should just call
+    // clear() before deleting the Recycler.
+    assert(FreeList.empty() && "Non-empty recycler deleted!");
+  }
+
+  /// clear - Release all the tracked allocations to the allocator. The
+  /// recycler must be free of any tracked allocations before being
+  /// deleted; calling clear is one way to ensure this.
+  template<class AllocatorType>
+  void clear(AllocatorType &Allocator) {
+    while (!FreeList.empty()) {
+      T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin()));
+      Allocator.Deallocate(t);
+    }
+  }
+
+  template<class SubClass, class AllocatorType>
+  SubClass *Allocate(AllocatorType &Allocator) {
+    assert(sizeof(SubClass) <= Size &&
+           "Recycler allocation size is less than object size!");
+    assert(AlignOf<SubClass>::Alignment <= Align &&
+           "Recycler allocation alignment is less than object alignment!");
+    return !FreeList.empty() ?
+           reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) :
+           static_cast<SubClass *>(Allocator.Allocate(Size, Align));
+  }
+
+  template<class AllocatorType>
+  T *Allocate(AllocatorType &Allocator) {
+    return Allocate<T>(Allocator);
+  }
+
+  template<class SubClass, class AllocatorType>
+  void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) {
+    FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element));
+  }
+
+  void PrintStats() {
+    PrintRecyclerStats(Size, Align, FreeList.size());
+  }
+};
+
+}
+
+#endif