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 "llvm/Support/ErrorHandling.h" 21 #include <cassert> 22 23 namespace llvm { 24 25 class BumpPtrAllocator; 26 27 /// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for 28 /// printing statistics. 29 /// 30 void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize); 31 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; 37 }; 38 39 template<> 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; } 46 47 mutable RecyclerStruct Sentinel; 48 RecyclerStruct *createSentinel() const { 49 return &Sentinel; 50 } 51 static void destroySentinel(RecyclerStruct *) {} 52 53 RecyclerStruct *provideInitialHead() const { return createSentinel(); } 54 RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); } 55 static void noteHead(RecyclerStruct*, RecyclerStruct*) {} 56 57 static void deleteNode(RecyclerStruct *) { 58 llvm_unreachable("Recycler's ilist_traits shouldn't see a deleteNode call!"); 59 } 60 }; 61 62 /// Recycler - This class manages a linked-list of deallocated nodes 63 /// and facilitates reusing deallocated memory in place of allocating 64 /// new memory. 65 /// 66 template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment> 67 class Recycler { 68 /// FreeList - Doubly-linked list of nodes that have deleted contents and 69 /// are not in active use. 70 /// 71 iplist<RecyclerStruct> FreeList; 72 73 public: 74 ~Recycler() { 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!"); 79 } 80 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); 89 } 90 } 91 92 /// Special case for BumpPtrAllocator which has an empty Deallocate() 93 /// function. 94 /// 95 /// There is no need to traverse the free list, pulling all the objects into 96 /// cache. 97 void clear(BumpPtrAllocator&) { 98 FreeList.clearAndLeakNodesUnsafely(); 99 } 100 101 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)); 110 } 111 112 template<class AllocatorType> 113 T *Allocate(AllocatorType &Allocator) { 114 return Allocate<T>(Allocator); 115 } 116 117 template<class SubClass, class AllocatorType> 118 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) { 119 FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element)); 120 } 121 122 void PrintStats() { 123 PrintRecyclerStats(Size, Align, FreeList.size()); 124 } 125 }; 126 127 } 128 129 #endif 130