Since @xu-shawn's refactor the acc pointer has become a bit unnecessary,
we can achieve the same behavior by using the dimension size to get the
right accumulator from the `AccumulatorState`. I think the acc pointer
has become a bit of a burden required to be passed through multiple
different functions together with the necessary templating required.
Passed Non-Regression STC:
https://tests.stockfishchess.org/tests/view/67ed600f31d7cf8afdc45183
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 279744 W: 72037 L: 72082 D: 135625
Ptnml(0-2): 673, 29918, 78767, 29809, 705
closes https://github.com/official-stockfish/Stockfish/pull/5942
No functional change
Official release version of Stockfish 17.1
Bench: 2030154
---
Stockfish 17.1
Today, we have the pleasure to announce Stockfish 17.1. As always, you can
**freely** download it at [stockfishchess.org/download][1] and use it in the
[GUI of your choice][2].
Join our [Discord server][3] to get in touch with the community of developers
and users of the project!
Quality of chess play
In our testing against its predecessor, Stockfish 17.1 shows a consistent
improvement in performance, with an [Elo gain of up to 20 points][4] and
winning close to 2 times more game pairs than it loses.
Update highlights
New speedtest command
The new `speedtest` command benchmarks your computer's performance (measured in
nodes per second) using a realistic and stable test. To run it, you'll need
[command line access][5]—give it a try and share your results with the
community!
Improved hardware support
Stockfish is [no longer limited to 1024 threads][6] and will allow users to
specify whatever their system is capable of. Additionally, hardware such as
ppc64 and Loongson is now better supported at build time.
Bug fixes for tablebase support
Our previous release introduced improved engine lines (principal variations)
ending in mate as soon as a mate score is announced. A side effect of this
improvement was a [rare corner case][7] involving cursed tablebase wins, only
relevant in correspondence chess when the 50-move rule does not apply, which
has now been fixed. Relatedly, [time management][8] has also been improved to
avoid potential time losses.
Shoutouts
Download page redesign
We've redesigned the [download page][1] to address unclear wording and simplify
a previously cluttered experience. The page now features a modernized layout,
streamlined navigation, and clearer guidance to help you select the right
binary for your system.
Fishtest framework
Our testing framework has been improved in various ways, both on the worker
side, including the adoption of [Fastchess][9] as a new game manager, and on
the server side, such as streamlined configuration. The reliable availability
of testing resources is key for the progress of the engine.
Thank you
The Stockfish project builds on a thriving community of enthusiasts (thanks
everybody!) who contribute their expertise, time, and resources to build a free
and open-source chess engine that is robust, widely available, and very strong.
We would like to express our gratitude for the [12k stars][10] that light up
our GitHub project! Thank you for your support and encouragement – your
recognition means a lot to us.
We invite our chess fans to [join the Fishtest testing framework][11] to
contribute compute resources needed for development. Programmers can contribute
to the project either directly to [Stockfish][12] (C++), to [Fishtest][13]
(HTML, CSS, JavaScript, and Python), to our trainer [nnue-pytorch][14] (C++ and
Python), or to our [website][15] (HTML, CSS/SCSS, and JavaScript).
The Stockfish team
[1]: https://stockfishchess.org/download
[2]: https://official-stockfish.github.io/docs/stockfish-wiki/Download-and-usage.html#download-a-chess-gui
[3]: https://discord.gg/GWDRS3kU6R
[4]: https://tests.stockfishchess.org/tests/view/67e7d2fd6682f97da2178fbd
[5]: https://official-stockfish.github.io/docs/stockfish-wiki/UCI-&-Commands.html#speedtest
[6]: 652a8874b5
[7]: 6c7c5c7e47
[8]: 0f9ae0d11c
[9]: https://github.com/Disservin/fastchess
[10]: https://github.com/official-stockfish/Stockfish/stargazers
[11]: https://official-stockfish.github.io/docs/fishtest-wiki/Running-the-Worker.html
[12]: https://github.com/official-stockfish/Stockfish
[13]: https://github.com/official-stockfish/fishtest
[14]: https://github.com/official-stockfish/nnue-pytorch
[15]: https://github.com/official-stockfish/stockfish-web
Helps gcc silence the warning about
```
warning: 'added' may be used uninitialized [-Wmaybe-uninitialized]
const IndexType offsetA0 = TransformedFeatureDimensions * added[0];
```
closes https://github.com/official-stockfish/Stockfish/pull/5950
No functional change
This PR updates the internal WDL model, using data from 2.6M games
played by the revisions since f3bfce3531.
Note that the normalizing constant increases only moderately from 372 to
377.
```
> ./updateWDL.sh --firstrev f3bfce3531
Running: ./updateWDL.sh --firstrev f3bfce3531 --lasttrev HEAD --materialMin 17 --EloDiffMax 5
started at: Sat 22 Mar 11:02:14 CET 2025
Look recursively in directory pgns for games with max nElo difference 5 using books matching "UHO_Lichess_4852_v..epd" for SF revisions between f3bfce3531 (from 2025-02-28 09:50:59 +0100) and HEAD (from 2025-03-21 11:22:59 +0100).
Based on 138253430 positions from 2579360 games, NormalizeToPawnValue should change from 372 to 377.
ended at: Sat 22 Mar 11:04:00 CET 2025
```
```
> cat scoreWDL.log
Converting evals with NormalizeData = {'momType': 'material', 'momMin': 17, 'momMax': 78, 'momTarget': 58, 'as': [-37.45051876, 121.19101539, -132.78783573, 420.70576692]}.
Reading eval stats from updateWDL.json.
Retained (W,D,L) = (33794348, 69943262, 34515820) positions.
Saved distribution plot to updateWDLdistro.png.
Fit WDL model based on material.
Initial objective function: 0.3648260131692729
Final objective function: 0.36482338611818094
Optimization terminated successfully.
const int NormalizeToPawnValue = 377;
Corresponding spread = 71;
Corresponding normalized spread = 0.1879431202530567;
Draw rate at 0.0 eval at material 58 = 0.9902694872976331;
Parameters in internal value units:
p_a = ((-13.500 * x / 58 + 40.928) * x / 58 + -36.828) * x / 58 + 386.830
p_b = ((96.534 * x / 58 + -165.791) * x / 58 + 90.897) * x / 58 + 49.296
constexpr double as[] = {-13.50030198, 40.92780883, -36.82753545, 386.83004070};
constexpr double bs[] = {96.53354896, -165.79058388, 90.89679019, 49.29561889};
Preparing plots.
Saved graphics to updateWDL.png.
Total elapsed time = 46.92s.
```
Only affects displayed `cp` and `wdl` values.
closes https://github.com/official-stockfish/Stockfish/pull/5939
No functional change
This fixes a TCEC timeloss, where slow DTZ TB7 access, in combination
with syzygy PV extension, led to a timeloss.
While the extension code correctly aborted after spending moveOverhead/2
time, the mainThread did not search sufficient nodes (512 in > 1s) to
trigger the stop in check_time. At the same time, totalTime exceeded
tm.maximum() due to the factors multiplying tm.optimum().
This corner case is fixed by checking also against the tm.maximum() at
each iteration.
Even though this problem can't be triggered on fishtest, the patch was
verified there.
Passed STC:
https://tests.stockfishchess.org/tests/view/67b99e1be99f8640b318810d
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 136832 W: 35625 L: 35518 D: 65689
Ptnml(0-2): 499, 14963, 37431, 14978, 545
closes https://github.com/official-stockfish/Stockfish/pull/5896
No functional change
Currently "info string" is being printed twice for the network arch
```
info string info string NNUE evaluation using nn-1c0000000000.nnue (133MiB, (22528, 3072, 15, 32, 1))
info string info string NNUE evaluation using nn-37f18f62d772.nnue (6MiB, (22528, 128, 15, 32, 1))
```
closes https://github.com/official-stockfish/Stockfish/pull/5889
No functional change
Use std::is_arithmetic_v as it is the more modern and concise way to
check for arithmetic types. While at it, fixing a static assert in
misc.h, thanks to Shawn and Disservin for helping.
closes https://github.com/official-stockfish/Stockfish/pull/5883
No functional change
