1 //==- llvm/Support/Recycler.h - Recycling Allocator --------------*- C++ -*-==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the Recycler class template. See the doxygen comment for
11 // Recycler for more details.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_RECYCLER_H
16 #define LLVM_SUPPORT_RECYCLER_H
18 #include "llvm/ADT/ilist.h"
19 #include "llvm/Support/AlignOf.h"
20 #include "llvm/Support/ErrorHandling.h"
25 class BumpPtrAllocator;
27 /// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for
28 /// printing statistics.
30 void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize);
32 /// RecyclerStruct - Implementation detail for Recycler. This is a
33 /// class that the recycler imposes on free'd memory to carve out
34 /// next/prev pointers.
35 struct RecyclerStruct {
36 RecyclerStruct *Prev, *Next;
40 struct ilist_traits<RecyclerStruct> :
41 public ilist_default_traits<RecyclerStruct> {
42 static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; }
43 static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; }
44 static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; }
45 static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; }
47 mutable RecyclerStruct Sentinel;
48 RecyclerStruct *createSentinel() const {
51 static void destroySentinel(RecyclerStruct *) {}
53 RecyclerStruct *provideInitialHead() const { return createSentinel(); }
54 RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); }
55 static void noteHead(RecyclerStruct*, RecyclerStruct*) {}
57 static void deleteNode(RecyclerStruct *) {
58 llvm_unreachable("Recycler's ilist_traits shouldn't see a deleteNode call!");
62 /// Recycler - This class manages a linked-list of deallocated nodes
63 /// and facilitates reusing deallocated memory in place of allocating
66 template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment>
68 /// FreeList - Doubly-linked list of nodes that have deleted contents and
69 /// are not in active use.
71 iplist<RecyclerStruct> FreeList;
75 // If this fails, either the callee has lost track of some allocation,
76 // or the callee isn't tracking allocations and should just call
77 // clear() before deleting the Recycler.
78 assert(FreeList.empty() && "Non-empty recycler deleted!");
81 /// clear - Release all the tracked allocations to the allocator. The
82 /// recycler must be free of any tracked allocations before being
83 /// deleted; calling clear is one way to ensure this.
84 template<class AllocatorType>
85 void clear(AllocatorType &Allocator) {
86 while (!FreeList.empty()) {
87 T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin()));
88 Allocator.Deallocate(t);
92 /// Special case for BumpPtrAllocator which has an empty Deallocate()
95 /// There is no need to traverse the free list, pulling all the objects into
97 void clear(BumpPtrAllocator&) {
98 FreeList.clearAndLeakNodesUnsafely();
101 template<class SubClass, class AllocatorType>
102 SubClass *Allocate(AllocatorType &Allocator) {
103 assert(sizeof(SubClass) <= Size &&
104 "Recycler allocation size is less than object size!");
105 assert(AlignOf<SubClass>::Alignment <= Align &&
106 "Recycler allocation alignment is less than object alignment!");
107 return !FreeList.empty() ?
108 reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) :
109 static_cast<SubClass *>(Allocator.Allocate(Size, Align));
112 template<class AllocatorType>
113 T *Allocate(AllocatorType &Allocator) {
114 return Allocate<T>(Allocator);
117 template<class SubClass, class AllocatorType>
118 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) {
119 FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element));
123 PrintRecyclerStats(Size, Align, FreeList.size());