1//===-- tsan_clock.h --------------------------------------------*- 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 is a part of ThreadSanitizer (TSan), a race detector.
11//
12//===----------------------------------------------------------------------===//
13#ifndef TSAN_CLOCK_H
14#define TSAN_CLOCK_H
15
16#include "tsan_defs.h"
17#include "tsan_dense_alloc.h"
18
19namespace __tsan {
20
21struct ClockElem {
22  u64 epoch  : kClkBits;
23  u64 reused : 64 - kClkBits;
24};
25
26struct ClockBlock {
27  static const uptr kSize = 512;
28  static const uptr kTableSize = kSize / sizeof(u32);
29  static const uptr kClockCount = kSize / sizeof(ClockElem);
30
31  union {
32    u32       table[kTableSize];
33    ClockElem clock[kClockCount];
34  };
35
36  ClockBlock() {
37  }
38};
39
40typedef DenseSlabAlloc<ClockBlock, 1<<16, 1<<10> ClockAlloc;
41typedef DenseSlabAllocCache ClockCache;
42
43// The clock that lives in sync variables (mutexes, atomics, etc).
44class SyncClock {
45 public:
46  SyncClock();
47  ~SyncClock();
48
49  uptr size() const {
50    return size_;
51  }
52
53  u64 get(unsigned tid) const {
54    return elem(tid).epoch;
55  }
56
57  void Resize(ClockCache *c, uptr nclk);
58  void Reset(ClockCache *c);
59
60  void DebugDump(int(*printf)(const char *s, ...));
61
62 private:
63  friend struct ThreadClock;
64  static const uptr kDirtyTids = 2;
65
66  unsigned release_store_tid_;
67  unsigned release_store_reused_;
68  unsigned dirty_tids_[kDirtyTids];
69  // tab_ contains indirect pointer to a 512b block using DenseSlabAlloc.
70  // If size_ <= 64, then tab_ points to an array with 64 ClockElem's.
71  // Otherwise, tab_ points to an array with 128 u32 elements,
72  // each pointing to the second-level 512b block with 64 ClockElem's.
73  ClockBlock *tab_;
74  u32 tab_idx_;
75  u32 size_;
76
77  ClockElem &elem(unsigned tid) const;
78};
79
80// The clock that lives in threads.
81struct ThreadClock {
82 public:
83  typedef DenseSlabAllocCache Cache;
84
85  explicit ThreadClock(unsigned tid, unsigned reused = 0);
86
87  u64 get(unsigned tid) const {
88    DCHECK_LT(tid, kMaxTidInClock);
89    return clk_[tid].epoch;
90  }
91
92  void set(unsigned tid, u64 v);
93
94  void set(u64 v) {
95    DCHECK_GE(v, clk_[tid_].epoch);
96    clk_[tid_].epoch = v;
97  }
98
99  void tick() {
100    clk_[tid_].epoch++;
101  }
102
103  uptr size() const {
104    return nclk_;
105  }
106
107  void acquire(ClockCache *c, const SyncClock *src);
108  void release(ClockCache *c, SyncClock *dst) const;
109  void acq_rel(ClockCache *c, SyncClock *dst);
110  void ReleaseStore(ClockCache *c, SyncClock *dst) const;
111
112  void DebugReset();
113  void DebugDump(int(*printf)(const char *s, ...));
114
115 private:
116  static const uptr kDirtyTids = SyncClock::kDirtyTids;
117  const unsigned tid_;
118  const unsigned reused_;
119  u64 last_acquire_;
120  uptr nclk_;
121  ClockElem clk_[kMaxTidInClock];
122
123  bool IsAlreadyAcquired(const SyncClock *src) const;
124  void UpdateCurrentThread(SyncClock *dst) const;
125};
126
127}  // namespace __tsan
128
129#endif  // TSAN_CLOCK_H
130