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/Allocator.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 /// Recycler - This class manages a linked-list of deallocated nodes 31 /// and facilitates reusing deallocated memory in place of allocating 32 /// new memory. 33 /// 34 template <class T, size_t Size = sizeof(T), size_t Align = alignof(T)> 35 class Recycler { 36 struct FreeNode { 37 FreeNode *Next; 38 }; 39 40 /// List of nodes that have deleted contents and are not in active use. 41 FreeNode *FreeList = nullptr; 42 43 FreeNode *pop_val() { 44 auto *Val = FreeList; 45 FreeList = FreeList->Next; 46 return Val; 47 } 48 49 void push(FreeNode *N) { 50 N->Next = FreeList; 51 FreeList = N; 52 } 53 54 public: 55 ~Recycler() { 56 // If this fails, either the callee has lost track of some allocation, 57 // or the callee isn't tracking allocations and should just call 58 // clear() before deleting the Recycler. 59 assert(!FreeList && "Non-empty recycler deleted!"); 60 } 61 62 /// clear - Release all the tracked allocations to the allocator. The 63 /// recycler must be free of any tracked allocations before being 64 /// deleted; calling clear is one way to ensure this. 65 template<class AllocatorType> 66 void clear(AllocatorType &Allocator) { 67 while (FreeList) { 68 T *t = reinterpret_cast<T *>(pop_val()); 69 Allocator.Deallocate(t); 70 } 71 } 72 73 /// Special case for BumpPtrAllocator which has an empty Deallocate() 74 /// function. 75 /// 76 /// There is no need to traverse the free list, pulling all the objects into 77 /// cache. 78 void clear(BumpPtrAllocator &) { FreeList = nullptr; } 79 80 template<class SubClass, class AllocatorType> 81 SubClass *Allocate(AllocatorType &Allocator) { 82 static_assert(alignof(SubClass) <= Align, 83 "Recycler allocation alignment is less than object align!"); 84 static_assert(sizeof(SubClass) <= Size, 85 "Recycler allocation size is less than object size!"); 86 return FreeList ? reinterpret_cast<SubClass *>(pop_val()) 87 : static_cast<SubClass *>(Allocator.Allocate(Size, Align)); 88 } 89 90 template<class AllocatorType> 91 T *Allocate(AllocatorType &Allocator) { 92 return Allocate<T>(Allocator); 93 } 94 95 template<class SubClass, class AllocatorType> 96 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) { 97 push(reinterpret_cast<FreeNode *>(Element)); 98 } 99 100 void PrintStats(); 101 }; 102 103 template <class T, size_t Size, size_t Align> 104 void Recycler<T, Size, Align>::PrintStats() { 105 size_t S = 0; 106 for (auto *I = FreeList; I; I = I->Next) 107 ++S; 108 PrintRecyclerStats(Size, Align, S); 109 } 110 111 } 112 113 #endif 114
