Also renamed history access value in something more
in line with the meaning.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It seems there is absolutely no difference in using gains.
After 7025 games at 5"+0
Mod vs Orig +1903 =3236 -1886 (+1 ELO)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Many killers moves, around 40%, are not legal, so
skip earlier in this case.
Some Movepicker c'tor cleanup while there.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is the world's fussiest compiler with +w1
Warnings reported by Richard Lloyd.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Consider sligtly negative captures as good if at low
depth and far from beta.
After 999 games at 1+0
Mod vs Orig +169 =694 -136 +11 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Gain value is multiplied by 16 to be of comparable magnitudo
of negative history, on average.
This patch shows very good results in tactical tests, but
started very bad in real games, so I have run two test matches.
After 896 games at 1+0
Mod vs Orig +187 =525 -184 +1 ELO
After 999 games at 1+0
Mod vs Orig +223 =590 -186 +13 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We can do this only when needed, if we get a cut-off
before we skip sorting entirely. This reduces sorting
time of about 20%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Because H.move_ordering_score() can return negative values
some negative see moves could be searched before non-negative
see moves with negative history.
This patch restores proper ordering.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Now that history can go negative and is almost alwyas
non zero we have no more reasons to use also psqt term.
After 994 games at 1+0
Mod vs Orig +204 =597 -193 +4 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Under some rare cases we can have a search tree explosion
due to a perpetual check or to a very long non-capture TT
sequence.
This avoids the tree explosion not following TT moves that
are not captures or promotions when we are below the
'generate checks' depth.
Idea suggested by Richard Vida.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Avoid to take the lock two times in a tight sequence, the first
in get_next_move() and the second to update sp->moves.
Do all with one lock and so retire the now useless locked version
of get_next_move().
Also fix some theorical race due to comparison sp->bestValue < sp->beta
is done out of lock protection. Finally fix another (harmless but time
waster) race that coudl occur because thread_should_stop() is also
called outside of lock protection.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use the same scoring system used for evasions. Small if any
increase, but should be in at least for completeness.
After 999 games at 1+0
Mod vs Orig +208 =601 -190 +6 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is not useful becasue it is safe to call
get_next_move() multiple times when phase == PH_STOP
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Increases performance because now we use one integer
for both midgame and endgame scores.
Unfortunatly the latest patches seem to have reduced a bit
the speed so at the end we are more or less at the same
performance level of the beginning. But this patch series
introduced also some code cleanup so it is the main reason
we commit anyway.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of MgPieceSquareTable[16][64] and EgPieceSquareTable[16][64]
This allows to fetch mg and eg values from adjacent words in memory.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This allow us to avoid the generation of the
evasion moves if we already have a TT move, and
in case we have a cut-off we skip evasion generation
altoghter.
Node count is changed because now we try TT move _before_
to generate evasions. The search on the TT move alters the
piece lists so that when we come back to generate evasions
we build the move list with a diferent order and this alters
the node count.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is now no more needed to know dc candidates
inside MovePicker, so avoid calculating there.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Big cleanup and semplification of pawns evasions that
now are pseudo-legal as the remaining moves. This
allow us to remove a lot of tricky code.
Verified against perft: no functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This allow a big semplification in move generation
that will be committed with the next patch. And makes
handling of evasions similar to the other type of moves.
This patch plus the next seem to improve also on
the performance side because after 640 games to
verify there are no hidden regressions we are at +9 ELO
Verified with perft no functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Always try ttMove as first. Then try good captures ordered
by MVV/LVA, then non-captures if destination square is not
under attack, ordered by history value, and at the end
bad-captures and non-captures with a negative SEE. This
last group is ordered by the SEE score.
After 999 games at 1+0
Mod vs Orig +254 =546 -199 +19 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
When the move list is very small, like captures normally
are, it is faster to pick the best move with a linear
scan, one per cycle.
This has the added advantage that the picked capture move is
very possibly a cut-off move, so that other searches are
avoided. For non-captures it is still faster to sort in
advance.
Because scan-and-pick alghortim is not stable, node count
has changed.
After 885 games at 1+0
Mod vs Orig +196 =510 -179 50.96% 451.0/885
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is stable and it is also a bit faster then std::sort()
on the tipical small move lists that we need to handle.
Verified to have same functionality of std::stable_sort()
After 999 games at 1+0
Mod vs Orig +240 =534 -225 50.75% 507.0/999 +5 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Unfortunatly std::stable_sort() implementation in gcc is
horrendously slow. We have a big performance regression on
Linux systems (-20% !)
So revert the commit and wait to fix the issue in a different
way, perhaps with an our home grown sorting, that should be
comparable in speed with std::sort()
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Standard does not mandate std::sort() to be stable, so we
can have, and actually do have different node count on
different platforms.
So use the platform independent std::stable_sort() and gain
same functionality on any platform (Windows, Unix, Mac OS)
and with any compiler (MSVC, gcc or Intel C++).
This sort is teoretically slower, but profiling shows only a very
minimal drop in performance, probably due to the fact that
the set to sort is very small, mainly only captures and with
less frequency non-captures, anyhow we are talking of 30-40 moves
in the worst average case. Sorting alghortims are build to work on
thousands or even milions of elements. With such small sets
performance difference seems not noticable.
After 999 games at 1+0
Mod vs Orig +234 =523 -242 -3 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It is more clear that only in that case the move number is
correct, otherwise is only a partial quantity: the number of
moves of that phase.
In case of PH_EVASIONS instead we have only one phase.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
If we don't have tt moves to search skip the
useless loop associated with TT_MOVES phase.
Another 1% speed boost that brings this series
to a +6.2% against original revision 595a90df
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This not only cleans up the code but gives another
speed boost of 1.8%
From revision 595a90dfd0 we have increased pgo compiled binary
speed of a whopping +5.2% without any functional change !!
This is really awsome considering that we have also
cut line count by 25 lines.
Sometime we spend days for getting an extra 1% from move
generation while instead the biggest optimizations come
from anonymous and apparently dull parts of the code.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Does not seem to improve on the standard, latest results
from Joona after 2040 games are negative:
Orig - Mod: 454 - 424 - 1162
And is more or less the same I got few days ago.
So revert for now.
Verified same functionality of 595a90dfd
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use the same way of loop along the move list used for
the others move kinds so to be consistent in get_next_move()
And a bit of the usual clean up too, but just a bit.
It is even a bit (+0.3%) faster now. ;-)
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Always after TT move but before captures.
This seems a better setup against version before this
patch.
After 999 games at 1+0
Mod - Orig +252 =527 -220 +11 ELO
Unfortunatly it does not seems to improve on the standard
version, with null move outside of movepicker (595a90df) with
the latest speed-up patches added in.
After 999 games at 1+0
Mod - Standard +244 =506 -249 -2 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This avoids calculating the array entry position
at each access and gives another boost of almost 1%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In MovePicker we get the next move with pick_move_from_list(),
then check if the return value is equal to MOVE_NONE and
in this case we update the state to the new phase.
This patch reorders the flow so that now from pick_move_from_list()
renamed get_next_move() we directly call go_next_phase() to
generate and sort the next bunch of moves when there are no more
move to try. This avoids to always check for pick_move_from_list()
returned value and the flow is more linear and natural.
Also use a local variable instead of a pointer dereferencing in a
time critical switch statement in get_next_move()
With this patch alone we have an incredible speed up of 3.2% !!!
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Try good captures before null move when depth < 3 * OnePly.
Use this kind of null move also in Depth == OnePly.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Original patch from Joona with added optimizations
by me.
Great cleanup of MovePicker with speed improvment of 1%
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In Movepicker c'tor we access during initialization one of
MainSearchPhaseIndex..QsearchWithoutChecksPhaseIndex globals.
Postpone definition of PhaseTable[] just after them so that
when PhaseTable[] will be accessed later in get_next_move()
it will be already present in L1/L2.
It works like an implicit prefetching of PhaseTable[].
Also shrink PhaseTable[] to fit an L1 cache line of 16 bytes
using uint8_t instead of int.
This apparentely innocuous patch gives an astonish speed
up of 1.6% under MSVC 2010 beta, pgo optimized !
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
When ordering moves we push all captures with negative SEE values
to badCaptures[] array during the scoring phase.
This patch delays the costly SEE call up to when the move has been
picked up in pick_move_from_list(), this way we save some SEE calls
in case we get a cutoff.
It seems we have a speed gain of about 1-1.5 % in terms of nodes/sec
and profiling seems to confirm the small but real speed increase.
Idea from Pablo Vazquez on talkchess.com
http://www.talkchess.com/forum/viewtopic.php?t=29018&start=20
It would be a no functional change but actually it is not because
now sorting set is different and so std::sort(), that is not a
stable sort, does not guarantees the order of same scored moves to
remain the same as before.
After 952 games at 1+0 we are below error bar, almost equal just
6 games of difference (+2 ELO)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Mostly of times we are interested only in the sign of SEE,
namely if a capture is negative or not.
If the capturing piece is smaller then the captured one we
already know SEE cannot be negative and this information
is enough most of the times. And of course it is much
faster to detect then a full SEE.
Note that in case see_sign() is negative then the returned
value is exactly the see() value, this is very important,
especially for ordering capturing moves.
With this patch the calls to the costly see() are reduced
of almost 30%.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead of add and subtract pqst values corrisponding to
the move starting and destination squares, do it in one
go with the helper function pst_delta<>()
This simplifies the code and also better documents that what
we need is a delta value, not an absolute one.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Rename to move_is_promotion() to be more clear, also add
a new function move_promotion_piece() to get the
promotion piece type in the few places where is needed.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This was needed by an old optimization in sorting of
non-captures that is now obsoleted by new std::sort()
approach.
Remove also the unused depth member data. Interestingly
this has always been unused since the Glaurung days.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is a first step for future patches and in
any case seems a nice thing to do.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In MovePicker consider killer moves as a separate
phase from non-capture picking.
Note that this change guarantees that killer1 is always
tried before killer2. Until now, because scoring difference
of the two moves was just 1 point, if psqt tables of killer1
gave a lower value then killer2, the latter was tried as first.
After 999 games at 1+0 we have
Mod vs Orig: +245 =527 -227 +6 ELO
Not a lot but patch is anyhow something worth to have.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
