This patch introduces three additional correction histories, namely,
Major Piece Correction History, Minor Piece Correction History, and
Non-Pawn Correction History.
Introduced by @mcthouacbb in Sirius
(https://github.com/mcthouacbb/Sirius) chess engine. The Major Piece
Correction History is indexed by side-to-move and the Zobrist key
representing the position of the King, Rook, and Queen of both sides.
Likewise, the Minor Piece Correction History is indexed by side-to-move
and the Zobrist key representing the position of the King, Knight, and
Bishop of both sides.
Also See:
97b85bbaac3099cdef2f
Introduced by @zzzzz151 in Starzix (https://github.com/zzzzz151/Starzix)
chess engine. Non-Pawn correction history consists of side-to-move, side
of Zobrist key, and a Zobrist key representing of the position of all
non-pawn pieces of **one side**. The non-pawn correction values for both
key sides are then summed.
Also See:
34911772f133e0df8dd2
The weights on the final correction value of the above correction
histories, as well as existing correction histories, are then tuned in
two separate SPSA sessions, totaling 75k games.
SPSA1:
https://tests.stockfishchess.org/tests/view/66e5243886d5ee47d953a86b
(Stopped early due to some weights reaching the maximum value)
SPSA2:
https://tests.stockfishchess.org/tests/view/66e6a26f86d5ee47d953a965
Also thanks to @martinnovaak, (Motor
https://github.com/martinnovaak/motor author) for insights and
suggestions.
Passed STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 23328 W: 6197 L: 5901 D: 11230
Ptnml(0-2): 82, 2582, 6041, 2876, 83
https://tests.stockfishchess.org/tests/view/66e8787b86d5ee47d953ab6f
Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 10626 W: 2826 L: 2560 D: 5240
Ptnml(0-2): 4, 1054, 2941, 1300, 14
https://tests.stockfishchess.org/tests/view/66e8ab2386d5ee47d953aba8
closes https://github.com/official-stockfish/Stockfish/pull/5598
Bench: 1011161
- remove the blank line between the declaration of the function and it's
comment, leads to better IDE support when hovering over a function to see it's
description
- remove the unnecessary duplication of the function name in the functions
description
- slightly refactored code for lsb, msb in bitboard.h There are still a few
things we can be improved later on, move the description of a function where
it was declared (instead of implemented) and add descriptions to functions
which are behind macros ifdefs
closes https://github.com/official-stockfish/Stockfish/pull/4840
No functional change
This introduces clang-format to enforce a consistent code style for Stockfish.
Having a documented and consistent style across the code will make contributing easier
for new developers, and will make larger changes to the codebase easier to make.
To facilitate formatting, this PR includes a Makefile target (`make format`) to format the code,
this requires clang-format (version 17 currently) to be installed locally.
Installing clang-format is straightforward on most OS and distros
(e.g. with https://apt.llvm.org/, brew install clang-format, etc), as this is part of quite commonly
used suite of tools and compilers (llvm / clang).
Additionally, a CI action is present that will verify if the code requires formatting,
and comment on the PR as needed. Initially, correct formatting is not required, it will be
done by maintainers as part of the merge or in later commits, but obviously this is encouraged.
fixes https://github.com/official-stockfish/Stockfish/issues/3608
closes https://github.com/official-stockfish/Stockfish/pull/4790
Co-Authored-By: Joost VandeVondele <Joost.VandeVondele@gmail.com>
Bit-shifting is a single instruction, and should be faster than an array lookup
on supported architectures. Besides (ever so slightly) speeding up the
conversion of a square into a bitboard, we may see minor general performance
improvements due to preserving more of the CPU's existing cache.
passed STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 47280 W: 12469 L: 12271 D: 22540
Ptnml(0-2): 128, 4893, 13402, 5087, 130
https://tests.stockfishchess.org/tests/view/63c5cfe618c20f4929c5fe46
Small speedup locally:
```
Result of 20 runs
==================
base (./stockfish.master ) = 1752135 +/- 10943
test (./stockfish.patch ) = 1763939 +/- 10818
diff = +11804 +/- 4731
speedup = +0.0067
P(speedup > 0) = 1.0000
CPU: 16 x AMD Ryzen 9 3950X 16-Core Processor
```
Closes https://github.com/official-stockfish/Stockfish/pull/4343
Bench: 4106793
We remark that in current master, most of our use cases for between_bb() can be
optimized if the second parameter of the function is added to the segment. So we
change the definition of between_bb(s1, s2) such that it excludes s1 but includes s2.
We also use a precomputed array for between_bb() for another small speed gain
(see https://tests.stockfishchess.org/tests/view/604d09f72433018de7a389fb).
Passed STC:
LLR: 2.96 (-2.94,2.94) {-0.25,1.25}
Total: 18736 W: 1746 L: 1607 D: 15383
Ptnml(0-2): 61, 1226, 6644, 1387, 50
https://tests.stockfishchess.org/tests/view/60428c84ddcba5f0627bb6e4
Yellow LTC:
LTC:
LLR: -3.00 (-2.94,2.94) {0.25,1.25}
Total: 39144 W: 1431 L: 1413 D: 36300
Ptnml(0-2): 13, 1176, 17184, 1178, 21
https://tests.stockfishchess.org/tests/view/605128702433018de7a38ca1
Closes https://github.com/official-stockfish/Stockfish/pull/3397
---------
Verified for correctness by running perft on the following position:
./stockfish
position fen 4rrk1/1p1nq3/p7/2p1P1pp/3P2bp/3Q1Bn1/PPPB4/1K2R1NR w - - 40 21
go perft 6
Nodes searched: 6136386434
--------
No functional change
The codebase contains multiple functions returning by const-value.
This patch is a small cleanup making those function returns
by value instead, removing the const specifier.
closes https://github.com/official-stockfish/Stockfish/pull/3328
No functional change
This patch ports the efficiently updatable neural network (NNUE) evaluation to Stockfish.
Both the NNUE and the classical evaluations are available, and can be used to
assign a value to a position that is later used in alpha-beta (PVS) search to find the
best move. The classical evaluation computes this value as a function of various chess
concepts, handcrafted by experts, tested and tuned using fishtest. The NNUE evaluation
computes this value with a neural network based on basic inputs. The network is optimized
and trained on the evalutions of millions of positions at moderate search depth.
The NNUE evaluation was first introduced in shogi, and ported to Stockfish afterward.
It can be evaluated efficiently on CPUs, and exploits the fact that only parts
of the neural network need to be updated after a typical chess move.
[The nodchip repository](https://github.com/nodchip/Stockfish) provides additional
tools to train and develop the NNUE networks.
This patch is the result of contributions of various authors, from various communities,
including: nodchip, ynasu87, yaneurao (initial port and NNUE authors), domschl, FireFather,
rqs, xXH4CKST3RXx, tttak, zz4032, joergoster, mstembera, nguyenpham, erbsenzaehler,
dorzechowski, and vondele.
This new evaluation needed various changes to fishtest and the corresponding infrastructure,
for which tomtor, ppigazzini, noobpwnftw, daylen, and vondele are gratefully acknowledged.
The first networks have been provided by gekkehenker and sergiovieri, with the latter
net (nn-97f742aaefcd.nnue) being the current default.
The evaluation function can be selected at run time with the `Use NNUE` (true/false) UCI option,
provided the `EvalFile` option points the the network file (depending on the GUI, with full path).
The performance of the NNUE evaluation relative to the classical evaluation depends somewhat on
the hardware, and is expected to improve quickly, but is currently on > 80 Elo on fishtest:
60000 @ 10+0.1 th 1
https://tests.stockfishchess.org/tests/view/5f28fe6ea5abc164f05e4c4c
ELO: 92.77 +-2.1 (95%) LOS: 100.0%
Total: 60000 W: 24193 L: 8543 D: 27264
Ptnml(0-2): 609, 3850, 9708, 10948, 4885
40000 @ 20+0.2 th 8
https://tests.stockfishchess.org/tests/view/5f290229a5abc164f05e4c58
ELO: 89.47 +-2.0 (95%) LOS: 100.0%
Total: 40000 W: 12756 L: 2677 D: 24567
Ptnml(0-2): 74, 1583, 8550, 7776, 2017
At the same time, the impact on the classical evaluation remains minimal, causing no significant
regression:
sprt @ 10+0.1 th 1
https://tests.stockfishchess.org/tests/view/5f2906a2a5abc164f05e4c5b
LLR: 2.94 (-2.94,2.94) {-6.00,-4.00}
Total: 34936 W: 6502 L: 6825 D: 21609
Ptnml(0-2): 571, 4082, 8434, 3861, 520
sprt @ 60+0.6 th 1
https://tests.stockfishchess.org/tests/view/5f2906cfa5abc164f05e4c5d
LLR: 2.93 (-2.94,2.94) {-6.00,-4.00}
Total: 10088 W: 1232 L: 1265 D: 7591
Ptnml(0-2): 49, 914, 3170, 843, 68
The needed networks can be found at https://tests.stockfishchess.org/nns
It is recommended to use the default one as indicated by the `EvalFile` UCI option.
Guidelines for testing new nets can be found at
https://github.com/glinscott/fishtest/wiki/Creating-my-first-test#nnue-net-tests
Integration has been discussed in various issues:
https://github.com/official-stockfish/Stockfish/issues/2823https://github.com/official-stockfish/Stockfish/issues/2728
The integration branch will be closed after the merge:
https://github.com/official-stockfish/Stockfish/pull/2825https://github.com/official-stockfish/Stockfish/tree/nnue-player-wip
closes https://github.com/official-stockfish/Stockfish/pull/2912
This will be an exciting time for computer chess, looking forward to seeing the evolution of
this approach.
Bench: 4746616
Adding a clamp function makes some of these range limitations a bit prettier and removes some #include's.
STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 28117 W: 6300 L: 6191 D: 15626
http://tests.stockfishchess.org/tests/view/5c9aa1df0ebc5925cfff8fcc
Non functional change.
This is a non-functional code style change.
If we add an accessor function for SquareBB we can consolidate all of the asserts. This is also a bit cleaner because all SquareBB accesses go through this method making future changes easier to manage.
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 63406 W: 14084 L: 14045 D: 35277
http://tests.stockfishchess.org/tests/view/5c9ea6100ebc5925cfffc9af
No functional change.
This is a non-functional simplification / code-style change.
This popcount16 method does nothing but initialize the PopCnt16 arrays.
This can be done in a single bitset line, which is less lines and more clear. Performance for this code is moot.
No functional change.
This is non-functional. These 5 arrays are simple enough to calculate real-time and maintaining an array for them does not help. Decreases the memory footprint.
This seems a tiny bit slower on my machine, but passed STC well enough. Could someone verify speed?
STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 44745 W: 9780 L: 9704 D: 25261
http://tests.stockfishchess.org/tests/view/5c47aa2d0ebc5902bca13fc4
The slowdown is minimal even in 32 bit case (thanks to @mstembera for testing):
Compiled using make build ARCH=x86-32 CXX=i686-w64-mingw32-c++ and benched
This patch only:
```
Results for 40 tests for each version:
Base Test Diff
Mean 1455204 1450033 5171
StDev 49452 34533 59621
p-value: 0.465
speedup: -0.004
```
No functional change.
This patch saves (4-1) * 64 * 64 = 12KiB of cache.
STC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 176120 W: 38944 L: 38087 D: 99089
http://tests.stockfishchess.org/tests/view/5c4c9f840ebc593af5d4a7ce
LTC
As a pure speed up, I've been informed it should not require LTC.
No functional change
This is a non-functional simplification that removes the AdjacentFiles array.
This array is simple enough to calculate that the pre-calculated array provides
no benefit. Reduces the memory footprint.
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 74839 W: 16390 L: 16373 D: 42076
http://tests.stockfishchess.org/tests/view/5c3d75920ebc596a450cfb67
No functionnal change
Preparation commit for the upcoming Stockfish 10 version, giving a chance to catch last minute feature bugs and evaluation regression during the one-week code freeze period. Also changing the copyright dates to include 2019.
No functional change
This is a non-functional change. By pre-incrementing minKingPawnDistance
instead of post-incrementing, we can remove this -1.
This also makes DistanceRing more consistent with the rest of stockfish
since it now holds an actual "distance" instead of a less natural distance-1.
In current master, PseudoAttacks[KING][ksq] == DistanceRingBB[ksq][0]
With this patch, it will be PseudoAttacks[KING][ksq] == DistanceRingBB[ksq][1]
ie squares at distance 1 from the king. This is more natural use of distance.
The current array size DistanceRingBB[SQUARE_NB][8] is still OK with the new
definition, because maximum distance between two squares on a chess board is
seven (for example Kh1 and a8).
No functional change.
In current master, the function make_bitboard() does nothing apart from
helping initialize the SquareBB[] array. This seems like an unnecessary
abstraction layer.
The advantage of make_bitboard() is we can define a bitboard, in a simple
and general way, not only from a single square but also from a list of
squares. It is more elegant, faster and readable than combining multiple
SquareBB explicitly, but the last complex use case in evaluation was
simplified away a few months ago.
If make_bitboard() becomes useful again to define complicated bitboards,
it will be easy enough to reintroduce it using this pull request as
an implementation reference.
No functional change.
1) Use make_bitboard() in Bitboards::init()
2) Fix MSVC warning: search.h(85): warning C4244: '=': conversion from
'TimePoint' to 'int', possible loss of data.
Closes https://github.com/official-stockfish/Stockfish/pull/1524
No functional change.
The NO_BSF does not cover any real life use-case today. The only compilers that
can compile SF today, with the current Makefile and no source code changes, are
either GCC compatible (define __GNUC__) or MSVC compatible (define _MSC_VER). So
they all support LSB/MSB intrinsics.
This patch simplifies away the software fall-backs of LSB/MSB that were still
in Stockfish code, but unused in any of the officially supported compilers.
Note the (legacy) MSVC/WIN32 case, where we use a 32-bit BSF/BSR solution, as
64-bit intrinsics aren't available there.
Discussed in: https://github.com/official-stockfish/Stockfish/pull/1447
and: https://github.com/official-stockfish/Stockfish/pull/1479
No functional change.
Currently the NORTH/WEST/SOUTH/EAST values are of type Square, but conceptually they are not squares but directions. This patch separates these values into a Direction enum and overloads addition and subtraction to allow adding a Square to a Direction (to get a new Square).
I have also slightly trimmed the possible overloadings to improve type safety. For example, it would normally not make sense to add a Color to a Color or a Piece to a Piece, or to multiply or divide them by an integer. It would also normally not make sense to add a Square to a Square.
This is a non-functional change.
Make magic_index() a member of Magic since it uses all it's members
and keep us from having to pass the function pointer around to
init_magics().
No functional change
Closes#1146
