In less then 1% of cases value > sp->bestValue, so avoid
an useless lock in the common case. This is the same change
already applied to sp_search().
Also SplitPoint futilityValue is not volatile because
never changes after has been assigned in split()
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
When we have more then 2 threads then we do an array
access with index 'Threads[slave].activeSplitPoints - 1'
This should be >= 0 because we tested the variable just
few statements before, but because is a shared variable
it could be that the 'slave' thread set the value to zero
just after we test it, so that when we use the decremented
variable for array access we crash.
Bug spotted by Bruno Causse.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
A pointer is enough because after a split point has been
setup master and slaves thread end up calling sp_search() or
sp_search_pv() and here a full copy of split point position is
done again, note that even master does another copy (of itself)
and this is done before any do_move() call so that master Position
is never updated between split() and sp_search().
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use futility pruning also in split points.
Do not use history pruning in split points when
getting mated.
After 1000 games on Joona QUAD
Orig - Mod: 496 - 504
Added an optimization to avoid a costly lock in the
very common case that sp->futilityValue <= sp->bestValue.
A test on a dual CPU shows only 114 hits on 23196 events,
so avoid a lock in all the other cases.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Testing on Joona QUAD failed to give any
advantage. Actually we had a little loss:
Mod - Orig: 342.0 - 374.0
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This reduces contention and reduce history trashing
effect especially at high search depths.
No functional change for single CPU case.
After 999 games at 1+0 on Dual Core Intel we have
Mod vs Orig +233 =526 -240 -2 ELO
We need to test at longer time controls and possibly with
a QUAD where we could foreseen an improvment.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This should reduce concurrent accessing in SMP case.
Suggestion by Tord Romstad.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
