1 files changed, 41 insertions, 12 deletions

diff --git a/libsanitizer/tsan/tsan_clock.h b/libsanitizer/tsan/tsan_clock.h
index 2ce480b2d16..3deb7f5198c 100644
--- a/libsanitizer/tsan/tsan_clock.h
+++ b/libsanitizer/tsan/tsan_clock.h
@@ -12,7 +12,7 @@
 #define TSAN_CLOCK_H
 
 #include "tsan_defs.h"
-#include "tsan_vector.h"
+#include "tsan_dense_alloc.h"
 
 namespace __tsan {
 
@@ -21,36 +21,65 @@ struct ClockElem {
   u64 reused : 64 - kClkBits;
 };
 
+struct ClockBlock {
+  static const uptr kSize = 512;
+  static const uptr kTableSize = kSize / sizeof(u32);
+  static const uptr kClockCount = kSize / sizeof(ClockElem);
+
+  union {
+    u32       table[kTableSize];
+    ClockElem clock[kClockCount];
+  };
+
+  ClockBlock() {
+  }
+};
+
+typedef DenseSlabAlloc<ClockBlock, 1<<16, 1<<10> ClockAlloc;
+typedef DenseSlabAllocCache ClockCache;
+
 // The clock that lives in sync variables (mutexes, atomics, etc).
 class SyncClock {
  public:
   SyncClock();
+  ~SyncClock();
 
   uptr size() const {
-    return clk_.Size();
+    return size_;
   }
 
   u64 get(unsigned tid) const {
-    DCHECK_LT(tid, clk_.Size());
-    return clk_[tid].epoch;
+    return elem(tid).epoch;
   }
 
-  void Reset();
+  void Resize(ClockCache *c, uptr nclk);
+  void Reset(ClockCache *c);
 
   void DebugDump(int(*printf)(const char *s, ...));
 
  private:
+  friend struct ThreadClock;
+  static const uptr kDirtyTids = 2;
+
   unsigned release_store_tid_;
   unsigned release_store_reused_;
-  static const uptr kDirtyTids = 2;
   unsigned dirty_tids_[kDirtyTids];
-  mutable Vector<ClockElem> clk_;
-  friend struct ThreadClock;
+  // tab_ contains indirect pointer to a 512b block using DenseSlabAlloc.
+  // If size_ <= 64, then tab_ points to an array with 64 ClockElem's.
+  // Otherwise, tab_ points to an array with 128 u32 elements,
+  // each pointing to the second-level 512b block with 64 ClockElem's.
+  ClockBlock *tab_;
+  u32 tab_idx_;
+  u32 size_;
+
+  ClockElem &elem(unsigned tid) const;
 };
 
 // The clock that lives in threads.
 struct ThreadClock {
  public:
+  typedef DenseSlabAllocCache Cache;
+
   explicit ThreadClock(unsigned tid, unsigned reused = 0);
 
   u64 get(unsigned tid) const {
@@ -73,10 +102,10 @@ struct ThreadClock {
     return nclk_;
   }
 
-  void acquire(const SyncClock *src);
-  void release(SyncClock *dst) const;
-  void acq_rel(SyncClock *dst);
-  void ReleaseStore(SyncClock *dst) const;
+  void acquire(ClockCache *c, const SyncClock *src);
+  void release(ClockCache *c, SyncClock *dst) const;
+  void acq_rel(ClockCache *c, SyncClock *dst);
+  void ReleaseStore(ClockCache *c, SyncClock *dst) const;
 
   void DebugReset();
   void DebugDump(int(*printf)(const char *s, ...));