PR middle-end/87041 - -Wformat reading through null pointer on unreachable code
[official-gcc.git] / libsanitizer / tsan / tsan_dense_alloc.h
blob197b96fdeedb2d44623ed12b1ce38c4c751868b9
1 //===-- tsan_dense_alloc.h --------------------------------------*- C++ -*-===//
2 //
3 // This file is distributed under the University of Illinois Open Source
4 // License. See LICENSE.TXT for details.
5 //
6 //===----------------------------------------------------------------------===//
7 //
8 // This file is a part of ThreadSanitizer (TSan), a race detector.
9 //
10 // A DenseSlabAlloc is a freelist-based allocator of fixed-size objects.
11 // DenseSlabAllocCache is a thread-local cache for DenseSlabAlloc.
12 // The only difference with traditional slab allocators is that DenseSlabAlloc
13 // allocates/free indices of objects and provide a functionality to map
14 // the index onto the real pointer. The index is u32, that is, 2 times smaller
15 // than uptr (hense the Dense prefix).
16 //===----------------------------------------------------------------------===//
17 #ifndef TSAN_DENSE_ALLOC_H
18 #define TSAN_DENSE_ALLOC_H
20 #include "sanitizer_common/sanitizer_common.h"
21 #include "tsan_defs.h"
22 #include "tsan_mutex.h"
24 namespace __tsan {
26 class DenseSlabAllocCache {
27 static const uptr kSize = 128;
28 typedef u32 IndexT;
29 uptr pos;
30 IndexT cache[kSize];
31 template<typename T, uptr kL1Size, uptr kL2Size> friend class DenseSlabAlloc;
34 template<typename T, uptr kL1Size, uptr kL2Size>
35 class DenseSlabAlloc {
36 public:
37 typedef DenseSlabAllocCache Cache;
38 typedef typename Cache::IndexT IndexT;
40 explicit DenseSlabAlloc(const char *name) {
41 // Check that kL1Size and kL2Size are sane.
42 CHECK_EQ(kL1Size & (kL1Size - 1), 0);
43 CHECK_EQ(kL2Size & (kL2Size - 1), 0);
44 CHECK_GE(1ull << (sizeof(IndexT) * 8), kL1Size * kL2Size);
45 // Check that it makes sense to use the dense alloc.
46 CHECK_GE(sizeof(T), sizeof(IndexT));
47 internal_memset(map_, 0, sizeof(map_));
48 freelist_ = 0;
49 fillpos_ = 0;
50 name_ = name;
53 ~DenseSlabAlloc() {
54 for (uptr i = 0; i < kL1Size; i++) {
55 if (map_[i] != 0)
56 UnmapOrDie(map_[i], kL2Size * sizeof(T));
60 IndexT Alloc(Cache *c) {
61 if (c->pos == 0)
62 Refill(c);
63 return c->cache[--c->pos];
66 void Free(Cache *c, IndexT idx) {
67 DCHECK_NE(idx, 0);
68 if (c->pos == Cache::kSize)
69 Drain(c);
70 c->cache[c->pos++] = idx;
73 T *Map(IndexT idx) {
74 DCHECK_NE(idx, 0);
75 DCHECK_LE(idx, kL1Size * kL2Size);
76 return &map_[idx / kL2Size][idx % kL2Size];
79 void FlushCache(Cache *c) {
80 SpinMutexLock lock(&mtx_);
81 while (c->pos) {
82 IndexT idx = c->cache[--c->pos];
83 *(IndexT*)Map(idx) = freelist_;
84 freelist_ = idx;
88 void InitCache(Cache *c) {
89 c->pos = 0;
90 internal_memset(c->cache, 0, sizeof(c->cache));
93 private:
94 T *map_[kL1Size];
95 SpinMutex mtx_;
96 IndexT freelist_;
97 uptr fillpos_;
98 const char *name_;
100 void Refill(Cache *c) {
101 SpinMutexLock lock(&mtx_);
102 if (freelist_ == 0) {
103 if (fillpos_ == kL1Size) {
104 Printf("ThreadSanitizer: %s overflow (%zu*%zu). Dying.\n",
105 name_, kL1Size, kL2Size);
106 Die();
108 VPrintf(2, "ThreadSanitizer: growing %s: %zu out of %zu*%zu\n",
109 name_, fillpos_, kL1Size, kL2Size);
110 T *batch = (T*)MmapOrDie(kL2Size * sizeof(T), name_);
111 // Reserve 0 as invalid index.
112 IndexT start = fillpos_ == 0 ? 1 : 0;
113 for (IndexT i = start; i < kL2Size; i++) {
114 new(batch + i) T;
115 *(IndexT*)(batch + i) = i + 1 + fillpos_ * kL2Size;
117 *(IndexT*)(batch + kL2Size - 1) = 0;
118 freelist_ = fillpos_ * kL2Size + start;
119 map_[fillpos_++] = batch;
121 for (uptr i = 0; i < Cache::kSize / 2 && freelist_ != 0; i++) {
122 IndexT idx = freelist_;
123 c->cache[c->pos++] = idx;
124 freelist_ = *(IndexT*)Map(idx);
128 void Drain(Cache *c) {
129 SpinMutexLock lock(&mtx_);
130 for (uptr i = 0; i < Cache::kSize / 2; i++) {
131 IndexT idx = c->cache[--c->pos];
132 *(IndexT*)Map(idx) = freelist_;
133 freelist_ = idx;
138 } // namespace __tsan
140 #endif // TSAN_DENSE_ALLOC_H