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/Allocator.h" 21#include "llvm/Support/ErrorHandling.h" 22#include <cassert> 23 24namespace llvm { 25 26/// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for 27/// printing statistics. 28/// 29void PrintRecyclerStats(size_t Size, size_t Align, size_t FreeListSize); 30 31/// RecyclerStruct - Implementation detail for Recycler. This is a 32/// class that the recycler imposes on free'd memory to carve out 33/// next/prev pointers. 34struct RecyclerStruct { 35 RecyclerStruct *Prev, *Next; 36}; 37 38template<> 39struct ilist_traits<RecyclerStruct> : 40 public ilist_default_traits<RecyclerStruct> { 41 static RecyclerStruct *getPrev(const RecyclerStruct *t) { return t->Prev; } 42 static RecyclerStruct *getNext(const RecyclerStruct *t) { return t->Next; } 43 static void setPrev(RecyclerStruct *t, RecyclerStruct *p) { t->Prev = p; } 44 static void setNext(RecyclerStruct *t, RecyclerStruct *n) { t->Next = n; } 45 46 mutable RecyclerStruct Sentinel; 47 RecyclerStruct *createSentinel() const { 48 return &Sentinel; 49 } 50 static void destroySentinel(RecyclerStruct *) {} 51 52 RecyclerStruct *provideInitialHead() const { return createSentinel(); } 53 RecyclerStruct *ensureHead(RecyclerStruct*) const { return createSentinel(); } 54 static void noteHead(RecyclerStruct*, RecyclerStruct*) {} 55 56 static void deleteNode(RecyclerStruct *) { 57 llvm_unreachable("Recycler's ilist_traits shouldn't see a deleteNode call!"); 58 } 59}; 60 61/// Recycler - This class manages a linked-list of deallocated nodes 62/// and facilitates reusing deallocated memory in place of allocating 63/// new memory. 64/// 65template<class T, size_t Size = sizeof(T), size_t Align = AlignOf<T>::Alignment> 66class Recycler { 67 /// FreeList - Doubly-linked list of nodes that have deleted contents and 68 /// are not in active use. 69 /// 70 iplist<RecyclerStruct> FreeList; 71 72public: 73 ~Recycler() { 74 // If this fails, either the callee has lost track of some allocation, 75 // or the callee isn't tracking allocations and should just call 76 // clear() before deleting the Recycler. 77 assert(FreeList.empty() && "Non-empty recycler deleted!"); 78 } 79 80 /// clear - Release all the tracked allocations to the allocator. The 81 /// recycler must be free of any tracked allocations before being 82 /// deleted; calling clear is one way to ensure this. 83 template<class AllocatorType> 84 void clear(AllocatorType &Allocator) { 85 while (!FreeList.empty()) { 86 T *t = reinterpret_cast<T *>(FreeList.remove(FreeList.begin())); 87 Allocator.Deallocate(t); 88 } 89 } 90 91 /// Special case for BumpPtrAllocator which has an empty Deallocate() 92 /// function. 93 /// 94 /// There is no need to traverse the free list, pulling all the objects into 95 /// cache. 96 void clear(BumpPtrAllocator&) { 97 FreeList.clearAndLeakNodesUnsafely(); 98 } 99 100 template<class SubClass, class AllocatorType> 101 SubClass *Allocate(AllocatorType &Allocator) { 102 static_assert(AlignOf<SubClass>::Alignment <= Align, 103 "Recycler allocation alignment is less than object align!"); 104 static_assert(sizeof(SubClass) <= Size, 105 "Recycler allocation size is less than object size!"); 106 return !FreeList.empty() ? 107 reinterpret_cast<SubClass *>(FreeList.remove(FreeList.begin())) : 108 static_cast<SubClass *>(Allocator.Allocate(Size, Align)); 109 } 110 111 template<class AllocatorType> 112 T *Allocate(AllocatorType &Allocator) { 113 return Allocate<T>(Allocator); 114 } 115 116 template<class SubClass, class AllocatorType> 117 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) { 118 FreeList.push_front(reinterpret_cast<RecyclerStruct *>(Element)); 119 } 120 121 void PrintStats() { 122 PrintRecyclerStats(Size, Align, FreeList.size()); 123 } 124}; 125 126} 127 128#endif 129