Rewritten hidden_checkers() to avoid calling
sliders attacks functions but just a much
faster squares_between()
Also a good code semplification.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of copying all, copy only the fields that
are updated incrementally, not the ones that are
recalcuated form scratch anyway.
This reduces copy overhead of 30%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is slower the previous uglier but faster code.
So completely restore old one for now :-(
Just leave in the rework of status backup/restore in do_move().
We will cherry pick bits of previous work once we are sure
we have fixed the performance regression.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Another optimization that let us remove another half
of find_hidden_checks(them, DcCandidates) calls.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This let us to calculate only pinners when we now that
dc candidates are not possible.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use a more strict condition to check if we have captured
an opponent pinner or hidden checker.
With this patch the occurrence of checkerCaptured == true are
reduced of 50%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In do_move() use previous pinned bitboards values to compute
the new one after the move. In particulary we end up with the
same bitboards in most cases. So detect these cases and just
keep the old values.
This should speedup a lot this slow computation in a very hot
path so that we can use this important info everywhere in the
code at very cheap cost.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
There was one occurence when the StateInfo variable went
out of scope before the corresponding Position object.
This yelds to a crash. Bug was not hit before because occurs
only when using an UCI interface and not the usual benchmark.
The fix consists in copying internally the content of the
about to stale StateInfo.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Remove pinned pieces from attacks when calculating
SEE value.
Algorithm is not perfect, there should be no false
positives, but can happen that we miss to remove a
pinned piece. Currently we don't cach 100% of cases,
but is a tradeoff between speed and accuracy. In any
case we stay on the safe side, so we remove an attacker
when we are sure it is pinned.
About only 0,5% of cases are affected by this patch, not
a lot given the hard work: this is a difficult patch!
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of copy the old state in the new one, copy only
fields that will be updated incrementally, not the ones
that will be recalculcated anyway.
This let us copy 13 bytes instead of 28 for each do_move()
call.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Probably is slightly slow, but code is surely better
in this way. We will optimize later for speed.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We don't backup anymore but use the renamed StateInfo
argument passed in do_move() to store the new position
state when doing a move.
Backup is now just revert to previous StateInfo that we know
because we store a pointer to it.
Note that now backing store is up to the caller, Position is
stateless in that regard, state is accessed through a pointer.
This patch will let us remove all the backup/restore copying,
just a pointer switch is now necessary.
Note that do_null_move() still uses StateInfo as backup.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We store it now in the same UndoInfo struct as 'previous'
field, so when doing a move we also know where to get
the previous info when undoing the back the move.
This is needed for future patches and is a nice cleanup anyway.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Also templetize compute_value() can be simpler now that
the above is templetized too.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This nice union trick let us optimize the speed and
remove the now unuseful backup() and restore() functions.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
After have been calculated cache their values
so to avoid another expensive call to hidden_checks()
if pinned_pieces() or discovered_check_candidates() are
called with the same position.
Add also interface to get pinners bitboard, we already have
this value so save it instead of discard.
Now that, after the first call to pinned_pieces() the following
are very cheap we can rewrite and cleanup all the checking handling.
So this patch is a prerequisite for future work.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
They hide the underlying uniform function call with
no benefit.
A little bit more verbose but now is clear what happens.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Currently fails if we test with a move that is not of
from the side to move but from the opponent.
This is the typical case of the threat from null move
search. The result is an erroneus prune of the defending
moves, see PruneDefendingMoves in ok_to_prune()
Fix the test to work also with threat moves.
Bug was always in but was unhidden by a patch of 17/12/2008
"Trigger of PawnEndgameExtension if capture is not a pawn"
Until then it was hidden by a tricky check in the prune
conditions instead of the natural move_is_capture()
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use Position::compute_material_key() to do the job,
so we are sure there is not key mismatch during
endgame function lookups.
This fixes two endgames hash errors that caused two
endgames to be disabled.
This patch is also a code cleanup because removes a lot
of messy key assignments.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In this case firstlocates the least valuable attacker, if any,
then proceed as usual.
This will be used by next patch.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Actually square 0 can be dirty, so that move_is_capture(0)
can return any random values.
Add an assert to be sure it is caught.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Make a copy of the position when needed instead
of passing as a reference. It is cleaner and
let us to simplify also Position::print()
A small space inflate while there.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Add infrastructure to threat killer moves as a vector,
this will allow us to easily parametrize the number of
killer moves, instead of hardcode this value to two as is now.
This patch just add the infrastructure, no functional
change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Teach Position::print() to optionally print a
given move in san notation in addition to
the ASCII representation of the board.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
