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      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_vector.h"
     18 
     19 namespace __tsan {
     20 
     21 struct ClockElem {
     22   u64 epoch  : kClkBits;
     23   u64 reused : 64 - kClkBits;
     24 };
     25 
     26 // The clock that lives in sync variables (mutexes, atomics, etc).
     27 class SyncClock {
     28  public:
     29   SyncClock();
     30 
     31   uptr size() const {
     32     return clk_.Size();
     33   }
     34 
     35   u64 get(unsigned tid) const {
     36     DCHECK_LT(tid, clk_.Size());
     37     return clk_[tid].epoch;
     38   }
     39 
     40   void Reset();
     41   void Zero();
     42 
     43   void DebugDump(int(*printf)(const char *s, ...));
     44 
     45  private:
     46   unsigned release_store_tid_;
     47   unsigned release_store_reused_;
     48   static const uptr kDirtyTids = 2;
     49   unsigned dirty_tids_[kDirtyTids];
     50   mutable Vector<ClockElem> clk_;
     51   friend struct ThreadClock;
     52 };
     53 
     54 // The clock that lives in threads.
     55 struct ThreadClock {
     56  public:
     57   explicit ThreadClock(unsigned tid, unsigned reused = 0);
     58 
     59   u64 get(unsigned tid) const {
     60     DCHECK_LT(tid, kMaxTidInClock);
     61     return clk_[tid].epoch;
     62   }
     63 
     64   void set(unsigned tid, u64 v);
     65 
     66   void set(u64 v) {
     67     DCHECK_GE(v, clk_[tid_].epoch);
     68     clk_[tid_].epoch = v;
     69   }
     70 
     71   void tick() {
     72     clk_[tid_].epoch++;
     73   }
     74 
     75   uptr size() const {
     76     return nclk_;
     77   }
     78 
     79   void acquire(const SyncClock *src);
     80   void release(SyncClock *dst) const;
     81   void acq_rel(SyncClock *dst);
     82   void ReleaseStore(SyncClock *dst) const;
     83 
     84   void DebugReset();
     85   void DebugDump(int(*printf)(const char *s, ...));
     86 
     87  private:
     88   static const uptr kDirtyTids = SyncClock::kDirtyTids;
     89   const unsigned tid_;
     90   const unsigned reused_;
     91   u64 last_acquire_;
     92   uptr nclk_;
     93   ClockElem clk_[kMaxTidInClock];
     94 
     95   bool IsAlreadyAcquired(const SyncClock *src) const;
     96   void UpdateCurrentThread(SyncClock *dst) const;
     97 };
     98 
     99 }  // namespace __tsan
    100 
    101 #endif  // TSAN_CLOCK_H
    102