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 /// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for 26 /// printing statistics. 27 /// 28 void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize); 29 30 /// RecyclerStruct - Implementation detail for Recycler. This is a 31 /// class that the recycler imposes on free'd memory to carve out 32 /// next/prev pointers. 33 struct RecyclerStruct { 34 RecyclerStruct *Prev, *Next; 35 }; 36 37 template<> 38 struct ilist_traits<RecyclerStruct> : 39 public ilist_default_traits<RecyclerStruct> { 40 static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; } 41 static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; } 42 static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; } 43 static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; } 44 45 mutable RecyclerStruct Sentinel; 46 RecyclerStruct *createSentinel() const { 47 return &Sentinel; 48 } 49 static void destroySentinel(RecyclerStruct *) {} 50 51 RecyclerStruct *provideInitialHead() const { return createSentinel(); } 52 RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); } 53 static void noteHead(RecyclerStruct*, RecyclerStruct*) {} 54 55 static void deleteNode(RecyclerStruct *) { 56 llvm_unreachable("Recycler's ilist_traits shouldn't see a deleteNode call!"); 57 } 58 }; 59 60 /// Recycler - This class manages a linked-list of deallocated nodes 61 /// and facilitates reusing deallocated memory in place of allocating 62 /// new memory. 63 /// 64 template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment> 65 class Recycler { 66 /// FreeList - Doubly-linked list of nodes that have deleted contents and 67 /// are not in active use. 68 /// 69 iplist<RecyclerStruct> FreeList; 70 71 public: 72 ~Recycler() { 73 // If this fails, either the callee has lost track of some allocation, 74 // or the callee isn't tracking allocations and should just call 75 // clear() before deleting the Recycler. 76 assert(FreeList.empty() && "Non-empty recycler deleted!"); 77 } 78 79 /// clear - Release all the tracked allocations to the allocator. The 80 /// recycler must be free of any tracked allocations before being 81 /// deleted; calling clear is one way to ensure this. 82 template<class AllocatorType> 83 void clear(AllocatorType &Allocator) { 84 while (!FreeList.empty()) { 85 T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin())); 86 Allocator.Deallocate(t); 87 } 88 } 89 90 template<class SubClass, class AllocatorType> 91 SubClass *Allocate(AllocatorType &Allocator) { 92 assert(sizeof(SubClass) <= Size && 93 "Recycler allocation size is less than object size!"); 94 assert(AlignOf<SubClass>::Alignment <= Align && 95 "Recycler allocation alignment is less than object alignment!"); 96 return !FreeList.empty() ? 97 reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) : 98 static_cast<SubClass *>(Allocator.Allocate(Size, Align)); 99 } 100 101 template<class AllocatorType> 102 T *Allocate(AllocatorType &Allocator) { 103 return Allocate<T>(Allocator); 104 } 105 106 template<class SubClass, class AllocatorType> 107 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) { 108 FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element)); 109 } 110 111 void PrintStats() { 112 PrintRecyclerStats(Size, Align, FreeList.size()); 113 } 114 }; 115 116 } 117 118 #endif 119