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
pop_val()43 FreeNode *pop_val() {
44 auto *Val = FreeList;
45 __asan_unpoison_memory_region(Val, Size);
46 FreeList = FreeList->Next;
47 __msan_allocated_memory(Val, Size);
48 return Val;
49 }
50
push(FreeNode * N)51 void push(FreeNode *N) {
52 N->Next = FreeList;
53 FreeList = N;
54 __asan_poison_memory_region(N, Size);
55 }
56
57 public:
~Recycler()58 ~Recycler() {
59 // If this fails, either the callee has lost track of some allocation,
60 // or the callee isn't tracking allocations and should just call
61 // clear() before deleting the Recycler.
62 assert(!FreeList && "Non-empty recycler deleted!");
63 }
64
65 /// clear - Release all the tracked allocations to the allocator. The
66 /// recycler must be free of any tracked allocations before being
67 /// deleted; calling clear is one way to ensure this.
68 template<class AllocatorType>
clear(AllocatorType & Allocator)69 void clear(AllocatorType &Allocator) {
70 while (FreeList) {
71 T *t = reinterpret_cast<T *>(pop_val());
72 Allocator.Deallocate(t);
73 }
74 }
75
76 /// Special case for BumpPtrAllocator which has an empty Deallocate()
77 /// function.
78 ///
79 /// There is no need to traverse the free list, pulling all the objects into
80 /// cache.
clear(BumpPtrAllocator &)81 void clear(BumpPtrAllocator &) { FreeList = nullptr; }
82
83 template<class SubClass, class AllocatorType>
Allocate(AllocatorType & Allocator)84 SubClass *Allocate(AllocatorType &Allocator) {
85 static_assert(alignof(SubClass) <= Align,
86 "Recycler allocation alignment is less than object align!");
87 static_assert(sizeof(SubClass) <= Size,
88 "Recycler allocation size is less than object size!");
89 return FreeList ? reinterpret_cast<SubClass *>(pop_val())
90 : static_cast<SubClass *>(Allocator.Allocate(Size, Align));
91 }
92
93 template<class AllocatorType>
Allocate(AllocatorType & Allocator)94 T *Allocate(AllocatorType &Allocator) {
95 return Allocate<T>(Allocator);
96 }
97
98 template<class SubClass, class AllocatorType>
Deallocate(AllocatorType &,SubClass * Element)99 void Deallocate(AllocatorType & /*Allocator*/, SubClass* Element) {
100 push(reinterpret_cast<FreeNode *>(Element));
101 }
102
103 void PrintStats();
104 };
105
106 template <class T, size_t Size, size_t Align>
PrintStats()107 void Recycler<T, Size, Align>::PrintStats() {
108 size_t S = 0;
109 for (auto *I = FreeList; I; I = I->Next)
110 ++S;
111 PrintRecyclerStats(Size, Align, S);
112 }
113
114 }
115
116 #endif
117