Finally we can now merge the 'ponderhit' case with
'stop' and 'quit'.
The patches have been done step by step to help debugging
becuase this is really tricky code.
No functional change.
Reset Limits.ponder only if search continue, but if
we are going to stop the search there is no need
(and is also confusing) to clear the 'ponder' flag.
This mimics the behaviour upon rceiving 'stop' when
pondering.
No functional change.
In SAN notation when two pieces of the same type can
move to a given destination square, a disambiguation
additional info (like starting file) shall be added
to the SAN move.
If one of the two pieces is pinned, the corresponding
move _could_ be illegal and in this case disambiguation
is not needed. But to be pinned alone it is not enough
to deduce that the move is illegal, for instance in this
position:
R3rk2/2r6/8/8/8/8/8/K7 b - - 0 1
The move Rc8 is ambiguous although the rook in e8 is pinned
and the correct SAN notation should be Rcc8.
No functional change.
Don't wait for the search to finish after a 'stop'
command, but keep processing the GUI input if any.
Also explicitly wake up the main thread (that could be
sleeping) after a 'stop' or 'quit' command and do not
rely on wait_for_search_finished() doing it for us.
This patch cleans up the code and functions's definitions,
but it is risky and needs a good test under different
conditions to be sure it does not introduces hungs up.
No functional change.
Revert patch c581b7ea36
Seems a regression after testing from Gary:
ELO: 7.24 +- 99%: 17.03 95%: 12.93
LOS: 97.86%
Wins: 439 Losses: 381 Draws: 1962
And mine:
After 5410 games at 15"+0.05
Wins: 936 Losses: 1141 Draws: 3333 ELO -13
Moreover we know that there is a regression in the range
of patches which include the fromNull patch.
Probably this is not the only regression since 2.3.1 and
perhaps the idea under fromNull is good, but at the moment,
while in deep regression hunting, better to be on the safe
side and revert it entirely.
My guess on why this is a regression is that using the
negated evaluation of previous ply in case of null search
fails to take in account the king safety asymmetry between
the two colors. This is of course just a guess.
bench 5503830
They are not self-describing and create a lot of user
requests about them.
Given that the values are already well tuned there
is no need to expose them as UCI options.
No functional change.
Sometimes is faster, but not always and on very long mates
produces strange scores probably due to truncation of PV
artifacts.
So simply perform normal search also in case of UCI 'mate x'
command, with the only difference that when a mate in x is
found search returns immediately.
No functional change.
Now that we can call 'bench' command also from
interactive terminal it makes no more sense to
exit the application if the user types a wrong
file name.
No functional change.
Since &-ing with SpaceMask restricts the set to the home
half of the board, it is possible to use just one popcount
instead of 2 by shifting "safe" to the other half of the
board. This gives a small speedup especially on systems
where hardware popcount is not available.
Patch kindly sent by Richard Vida.
No functional change.
It is now possible to run SF on a 'mate in x' testsuite.
For instance in case of a file with fen strings of
positions with mate in 10 we can now 'bench' on it:
stockfish bench 128 1 10 mate_in_10.epd mate
No functional change.
Following a user request I added the handling of UCI:
go mate x
Currently we just return from a PV node if x moves have been
done. Probably not the best approach. I have looked at Fruit/Toga
sources and there is even simpler: engine falls back on a fixed
depth search.
No functional change.
And return on using TT as backing store for position
evaluations.
Tests (even on single thread) show eval cache was a regression.
In multi thread result should be even worst because eval cache
is a per-thread struct, while TT is shared.
After 4957 games at 15"+0.05 (single thread)
eval cache vs master 969 - 1093 - 2895 -9 ELO
So previous reported result of +18 ELO was probably due to an
issue in the testing framework (a bug in cutechess-cli) that
has been fixed in the meanwhile.
bench: 5386711
In case of null search at low depths returns a fail low
due to a threat then, rather than return beta-1 (to cause
a re-search at full depth in the parent node), we set a flag
threatExtension = true (false by default) that will cause
moves that prevent the threat to be extended of one ply
in the following search.
Idea and patch is by Lucas Braesch.
Lucas also did the tests:
1500 games in 5"+0.05":
SF_threatExtension vs SF_20121222: 366 - 331 - 803 [51.2%] LOS=90.8%
3000 games in 10"+0.1":
SF_threatExtension vs SF_20121222: 610 - 559 - 1831 [50.8%] LOS=93.2%
Tests confirmed by Gary after 10570 games,
ELO: 2.79 +- 99%: 8.72 95%: 6.63
LOS: 94.08%
Wins: 1523 Losses: 1438 Draws: 7607
And finally by me at 15"+0.05, single thread, 3824 games
threatExtension vs master 768 - 692 - 2364 +7 ELO
bench 4918443
This is difficult code becuase a bug here could lead
to very subtle crashes in case of SMP games where we
have TT move corruption due to concurrent access.
Anyhow I have fully verified te code throwing at it
random moves. It shoudl work.
No functional change.
Test by Joona prooves the new feature don't value 70 added lines of code.
Grand totals after 10040 games (crashes: 0) for tt_both
master_9edc7 - 6a93488_6a934: 1756 - 1688 - 6596 ELO +2 (+- 2.7)
Confirmed by test of Gary:
After 8680 games:
ELO: 0.80 +- 99%: 9.62 95%: 7.31
LOS: 65.38%
Wins: 1288 Losses: 1268 Draws: 6130
Thanks a lot to both for testing it !!!
bench 5149248
This is more complex than what I'd like but I
was unable to split in small chunks.
Here we add 2 slots to TTEntry (valueUpper and depthUpper)
so that sizeof(TTEntry) returns to the original 16 bytes
and we can pack exactly 4 entries in a 64 bytes cache line.
Now we save an upper bound score alongside a lower (exact)
score. The idea is to increase TT cut-offs rates becuase
there is now an higher probability for a node to use TT info.
This patch is highly experimental and probably needs further
steps as is hinted by an unrealistic bench number:
bench: 2022385
In almost all cases we already know in advance that
color_of() argument is different from NO_PIECE.
So avoid the check for NO_PIECE in color_of() and
test at caller site in the very few places where
this case could occur.
As a nice side effect, this patch fixes a (bogus)
warning under some versions of gcc.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use an eval cache instead of TT to store node
position evaluations.
It is already an improvment and, because it frees
two TT entry slots, paves the way to extend TT to
store both upper and lower bounds.
After 4855 games, single thread, 15"+0.05
Mod vs Orig 1165 -920 - 2770 ELO +18
bench: 5149248
And document why this is an hard limit. It
seems for some (lucky) people 32 threads
are not enough.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In search(), after we evalute the position, in case there
isn't any TT entry we create one with just the evaluation
score.
This patches removes that code. The reason becuase the patch
deserves a single commit it is becuase introduces a (very small)
functional change due to the fact that the total number of
TT stores is less now and this slightly alters the TT hits
of our benchmark.
bench: 4983262
Rely fully on eval cache. Note that we still save eval
info to TT, this is not needed at this moment and will be
removed in future patches. We keep it so to have a "non
functional change" patch.
No functional change.
With this patch series we want to introduce a per-thread
evaluation cache to store node evaluation and do not
rely anymore on the TT table for this.
This patch just introduces the infrastructure.
No functional change.
Marco Costalba