1 //==- llvm/Support/Recycler.h - Recycling Allocator --------------*- C++ -*-==// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines the Recycler class template. See the doxygen comment for 11 // Recycler for more details. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_RECYCLER_H 16 #define LLVM_SUPPORT_RECYCLER_H 17 18 #include "llvm/ADT/ilist.h" 19 #include "llvm/Support/AlignOf.h" 20 #include <cassert> 21 22 namespace llvm { 23 24 /// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for 25 /// printing statistics. 26 /// 27 void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize); 28 29 /// RecyclerStruct - Implementation detail for Recycler. This is a 30 /// class that the recycler imposes on free'd memory to carve out 31 /// next/prev pointers. 32 struct RecyclerStruct { 33 RecyclerStruct *Prev, *Next; 34 }; 35 36 template<> 37 struct ilist_traits<RecyclerStruct> : 38 public ilist_default_traits<RecyclerStruct> { 39 static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; } 40 static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; } 41 static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; } 42 static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; } 43 44 mutable RecyclerStruct Sentinel; 45 RecyclerStruct *createSentinel() const { 46 return &Sentinel; 47 } 48 static void destroySentinel(RecyclerStruct *) {} 49 50 RecyclerStruct *provideInitialHead() const { return createSentinel(); } 51 RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); } 52 static void noteHead(RecyclerStruct*, RecyclerStruct*) {} 53 54 static void deleteNode(RecyclerStruct *) { 55 assert(0 && "Recycler's ilist_traits shouldn't see a deleteNode call!"); 56 } 57 }; 58 59 /// Recycler - This class manages a linked-list of deallocated nodes 60 /// and facilitates reusing deallocated memory in place of allocating 61 /// new memory. 62 /// 63 template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment> 64 class Recycler { 65 /// FreeList - Doubly-linked list of nodes that have deleted contents and 66 /// are not in active use. 67 /// 68 iplist<RecyclerStruct> FreeList; 69 70 public: 71 ~Recycler() { 72 // If this fails, either the callee has lost track of some allocation, 73 // or the callee isn't tracking allocations and should just call 74 // clear() before deleting the Recycler. 75 assert(FreeList.empty() && "Non-empty recycler deleted!"); 76 } 77 78 /// clear - Release all the tracked allocations to the allocator. The 79 /// recycler must be free of any tracked allocations before being 80 /// deleted; calling clear is one way to ensure this. 81 template<class AllocatorType> 82 void clear(AllocatorType &Allocator) { 83 while (!FreeList.empty()) { 84 T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin())); 85 Allocator.Deallocate(t); 86 } 87 } 88 89 template<class SubClass, class AllocatorType> 90 SubClass *Allocate(AllocatorType &Allocator) { 91 assert(sizeof(SubClass) <= Size && 92 "Recycler allocation size is less than object size!"); 93 assert(AlignOf<SubClass>::Alignment <= Align && 94 "Recycler allocation alignment is less than object alignment!"); 95 return !FreeList.empty() ? 96 reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) : 97 static_cast<SubClass *>(Allocator.Allocate(Size, Align)); 98 } 99 100 template<class AllocatorType> 101 T *Allocate(AllocatorType &Allocator) { 102 return Allocate<T>(Allocator); 103 } 104 105 template<class SubClass, class AllocatorType> 106 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) { 107 FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element)); 108 } 109 110 void PrintStats() { 111 PrintRecyclerStats(Size, Align, FreeList.size()); 112 } 113 }; 114 115 } 116 117 #endif 118