Add atomic_t<>::observe() (relaxed load)
Add atomic_fence_XXX() (barrier functions)
Get rid of MFENCE instruction, replace with no-op LOCK OR on stack.
Remove <atomic> dependence from stdafx.h and relevant headers.
Notification with "phantom value" could be useful in theory.
As an alternative way of sending signal from the notifier.
But current implementation is just useless.
Also fixed slow_mutex (not used anywhere).
Static initialization is all-zeros anyway.
But constexpr was killing my intellisense.
And probably also affected compile time.
Also make some internal structures hidden ("static").
Billions of events can reduce to thousands, saving CPU time a few s.
Only 4 slots are available (arbitrarily), and only 1 is usually used.
Other slots are used only for waiting on multiple atomics.
Takes ~80 ns instead of ~40 ns, same about deallocation.
Loops don't exist here, only 4-level semaphore tree.
Worst case only happens with concurrence, not from looping.
This optimization is not really necessary at current state of RPCS3.
This is more like to test C++ compilers and MSVC u128 implementation.
Remove unnecessary optimization from cond_alloc().
Optimistic case was absolutely dominating anyway.
Although the whole function is a dirty hack.
Now scanning through all threads is faster.
Compress 16-bit ref counter and two 48+64 bit slot allocators.
This allowed to remove some weird unnecessary logic paths.
Adjust hashtable size to keep it the same.
Instead of plain waiting while equal to some value,
it can be something like less, or greater, or even bitcount.
But it's a draft and untested. Hopefully doesn't break anything.
Hashtable increased and flatten, tree-alike extensions removed.
Some things simplified, so it can actually decrease perf a bit.
But most platforms shouldn't be affected.
Removed limit of 56 waiters per pointer.
Real limit now is about 65535.
Arbitrary maximum set to 8, but really we need 2, maybe 3.
Added atomic_wait::list object for multi-waiting.
Added atomic_wait::get_unique_tsc just in case.
Only compare masks for overlap for second overload (with mask provided).
Explicit "new value" can be provided in new 3-arg overloads.
Also rename atomic_storage_futex -> atomic_wait_engine.
Add pointer comparison to notifiers (to prevent spurious wakeups).
Fix a bug with a possible double notification in raw_notify().
Fix a bug with incorrect allocatin bit slots for cond_handle.
Add a semaphore counter to track max allowed number of threads.
Use #define for some constants to STRINGIZE them in errors.
Add some error messages when certain limits are reached.
Fix a bug with a wrong check simply throwing std::abort.
Use "special" notify_all patch with batch processing for every arch.
Fix Win7 bug who no one probably noticed.
Reduced static memory amount for waitable atomics.
Allow notifier to skip notifications if wait/notify masks don't overlap.
Improve raw_notify to wake up the thread by its id, add thread_id arg.
Add optional mask argument to notify_one() and notify_all().
