src/hotspot/share/utilities/singleWriterSynchronizer.cpp

*** 42,52 ****
  
  // Wait until all threads that entered a critical section before
  // synchronization have exited that critical section.
  void SingleWriterSynchronizer::synchronize() {
    // Side-effect in assert balanced by debug-only dec at end.
!   assert(Atomic::add(1u, &_writers) == 1u, "multiple writers");
    // We don't know anything about the muxing between this invocation
    // and invocations in other threads.  We must start with the latest
    // _enter polarity, else we could clobber the wrong _exit value on
    // the first iteration.  So fence to ensure everything here follows
    // whatever muxing was used.
--- 42,52 ----
  
  // Wait until all threads that entered a critical section before
  // synchronization have exited that critical section.
  void SingleWriterSynchronizer::synchronize() {
    // Side-effect in assert balanced by debug-only dec at end.
!   assert(Atomic::add(&_writers, 1u) == 1u, "multiple writers");
    // We don't know anything about the muxing between this invocation
    // and invocations in other threads.  We must start with the latest
    // _enter polarity, else we could clobber the wrong _exit value on
    // the first iteration.  So fence to ensure everything here follows
    // whatever muxing was used.
*** 62,72 ****
    // operations until this change of _enter succeeds.
    uint old;
    do {
      old = value;
      *new_ptr = ++value;
!     value = Atomic::cmpxchg(value, &_enter, old);
    } while (old != value);
    // Critical sections entered before we changed the polarity will use
    // the old exit counter.  Critical sections entered after the change
    // will use the new exit counter.
    volatile uint* old_ptr = &_exit[old & 1];
--- 62,72 ----
    // operations until this change of _enter succeeds.
    uint old;
    do {
      old = value;
      *new_ptr = ++value;
!     value = Atomic::cmpxchg(&_enter, old, value);
    } while (old != value);
    // Critical sections entered before we changed the polarity will use
    // the old exit counter.  Critical sections entered after the change
    // will use the new exit counter.
    volatile uint* old_ptr = &_exit[old & 1];