Stockfish Development Versions are build automatically if there are changes on the master branch in the git repository (https://github.com/official-stockfish/Stockfish). Use it at your own risk.
They are compiled with gcc 11.2/mingw 10 on Ubuntu 21.10.
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Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Sat Dec 18 17:19:21 2021 +0100
Timestamp: 1639844361

Adjust reductions based on current node delta and root delta

This patch is a follow up of previous 2 patches that introduced more reductions for PV nodes with low delta and more pruning for nodes with low delta. Instead of writing separate heuristics now it adjust reductions based on delta / rootDelta - it allows to remove 3 separate adjustements of pruning/LMR in different places and also makes reduction dependence on delta and rootDelta smoother. Also now it works for all pruning heuristics and not just 2.

Passed STC
https://tests.stockfishchess.org/tests/view/61ba9b6c57a0d0f327c2d48b
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 79192 W: 20513 L: 20163 D: 38516 Elo +1.54
Ptnml(0-2): 238, 8900, 21024, 9142, 292

passed LTC
https://tests.stockfishchess.org/tests/view/61baf77557a0d0f327c2eb8e
LLR: 2.96 (-2.94,2.94) <0.50,3.00>
Total: 158400 W: 41134 L: 40572 D: 76694 Elo +1.23
Ptnml(0-2): 101, 16372, 45745, 16828, 154

closes https://github.com/official-stockfish/Stockfish/pull/3862

bench 4651538
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: George Sobala
Date: Fri Dec 17 18:52:09 2021 +0100
Timestamp: 1639763529

Fix for profile-build failure using gcc on MacOS

Fixes https://github.com/official-stockfish/Stockfish/issues/3846 ,
where the profiling SF binary generated by GCC on MacOS would launch
but failed to quit. Tested with gcc-8, gcc9, gcc10, gcc-11.

The problem can be fixed by adding -fvisibility=hidden to the compiler
flags, see for example the following piece of Apple documentation:
https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/CppRuntimeEnv/Articles/SymbolVisibility.html

For instance this now works:
make -j8 profile-build ARCH=x86-64-avx2 COMP=gcc COMPCXX=g++-11

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: pb00067
Date: Fri Dec 17 18:37:41 2021 +0100
Timestamp: 1639762661

Remove lowPly history

Seems that after pull request #3731 (Capping stat bonus at 2000) this
heuristic is no longer useful.

STC:
https://tests.stockfishchess.org/tests/view/61b8d0e2dffbe89a35815444
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 30672 W: 7974 L: 7812 D: 14886 Elo +1.84
Ptnml(0-2): 106, 3436, 8072, 3634, 88

LTC:
https://tests.stockfishchess.org/tests/view/61b8e90cdffbe89a35815a67
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 42448 W: 10884 L: 10751 D: 20813 Elo +1.09
Ptnml(0-2): 23, 4394, 12267, 4507, 33

closes https://github.com/official-stockfish/Stockfish/pull/3853

bench: 4474950
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Fri Dec 17 18:22:48 2021 +0100
Timestamp: 1639761768

Simplify away singularQuietLMR

While at it, we also update the Elo estimate of reduction at non-PV nodes
(source: https://tests.stockfishchess.org/tests/view/61acf97156fcf33bce7d6303 )

STC:
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 243632 W: 62874 L: 63022 D: 117736 Elo -0.21
Ptnml(0-2): 810, 28024, 64249, 27970, 763
https://tests.stockfishchess.org/tests/view/61b8b1b7dffbe89a35814c0d

LTC:
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 91392 W: 23520 L: 23453 D: 44419 Elo +0.25
Ptnml(0-2): 51, 9568, 26387, 9643, 47
https://tests.stockfishchess.org/tests/view/61b97316dffbe89a35817da7

closes https://github.com/official-stockfish/Stockfish/pull/3854

bench: 4217785
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: farseer
Date: Fri Dec 17 18:12:47 2021 +0100
Timestamp: 1639761167

Update default net to nn-4401e826ebcc.nnue

Using data T60 12/1/20 to 11/2/2021, T74 4/22/21 to 7/27/21, T75 6/3/21 to 10/16/21, T76
(half of the randomly interleaved dataset due to a mistake merging) 11/10/21 to 11/21/21,
wrongIsRight_nodes5000pv2.binpack, and WrongIsRight-Reloaded.binpack combined and shuffled
position by position.

Trained with LR=4.375e-4 and WDL filtering enabled:

python train.py --smart-fen-skipping --random-fen-skipping 0 --features=HalfKAv2_hm^
--lambda=1.0 --max_epochs=800 --seed 910688689 --batch-size 16384
--progress_bar_refresh_rate 30 --threads 4 --num-workers 4 --gpus 1
--resume-from-model C:\msys64\home\Mike\nnue-pytorch\9b3d.pt
E:\trainingdata\T60-T74-T75-T76-WiR-WiRR-PbyP.binpack
E:\trainingdata\T60-T74-T75-T76-WiR-WiRR-PbyP.binpack

Passed STC
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 41848 W: 10962 L: 10676 D: 20210 Elo +2.37
Ptnml(0-2): 142, 4699, 11016, 4865, 202
https://tests.stockfishchess.org/tests/view/61ba886857a0d0f327c2cfd6

Passed LTC
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 27776 W: 7208 L: 6953 D: 13615 Elo +3.19
Ptnml(0-2): 14, 2808, 8007, 3027, 32
https://tests.stockfishchess.org/tests/view/61baae4d57a0d0f327c2d96f

closes https://github.com/official-stockfish/Stockfish/pull/3856

Bench: 4667591
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Tue Dec 14 13:41:12 2021 +0100
Timestamp: 1639485672

Remove NNUE scaling term

remove pawns scaling, probably correlated with piece scaling, and might be less useful with the recent improved nets. Might allow for another tune of the scaling params.

passed STC
https://tests.stockfishchess.org/tests/view/61afdb2e56fcf33bce7df31a
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 280864 W: 72198 L: 72399 D: 136267 Elo -0.25
Ptnml(0-2): 854, 32356, 74346, 31889, 987

passed LTC
https://tests.stockfishchess.org/tests/view/61b233a606b4c2dcb1b16140
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 400136 W: 102669 L: 103012 D: 194455 Elo -0.30
Ptnml(0-2): 212, 42005, 116047, 41522, 282

closes https://github.com/official-stockfish/Stockfish/pull/3851

Bench: 4735679
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Mon Dec 13 07:17:25 2021 +0100
Timestamp: 1639376245

Update default net to nn-d93927199b3d.nnue

Using the same dataset as before but slightly reduced initial LR as in
https://github.com/vondele/nnue-pytorch/tree/tweakLR1

passed STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 51368 W: 13492 L: 13191 D: 24685 Elo +2.04
Ptnml(0-2): 168, 5767, 13526, 6042, 181
https://tests.stockfishchess.org/tests/view/61b61f43dffbe89a3580b529

passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 45128 W: 11763 L: 11469 D: 21896 Elo +2.26
Ptnml(0-2): 24, 4583, 13063, 4863, 31
https://tests.stockfishchess.org/tests/view/61b6612edffbe89a3580c447

closes https://github.com/official-stockfish/Stockfish/pull/3848

Bench: 5121336
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stefan Geschwentner
Date: Sat Dec 11 15:56:38 2021 +0100
Timestamp: 1639234598

Simplify falling eval time factor.

Remove the difference to previous best score in falling eval calculation. As compensation double the effect of the difference to previous best average score.

STC:
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 86944 W: 22363 L: 22285 D: 42296 Elo +0.31
Ptnml(0-2): 273, 9227, 24396, 9301, 275
https://tests.stockfishchess.org/tests/view/61b111ce06b4c2dcb1b11546

LTC:
LLR: 2.96 (-2.94,2.94) <-2.25,0.25>
Total: 134944 W: 34606 L: 34596 D: 65742 Elo +0.03
Ptnml(0-2): 66, 12941, 41456, 12935, 74
https://tests.stockfishchess.org/tests/view/61b19ca206b4c2dcb1b13a8b

closes https://github.com/official-stockfish/Stockfish/pull/3841

Bench: 4729473
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Sat Dec 11 15:55:32 2021 +0100
Timestamp: 1639234532

Update Top CPU Contributors

closes https://github.com/official-stockfish/Stockfish/pull/3842

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Thu Dec 9 20:50:00 2021 +0100
Timestamp: 1639079400

Adjust singular extension depth restriction

This patch is a modification of original idea by lonfom169 which had a good yellow run
- do singular extension search with depth threshold 6 unless this is a PvNode with is a part of a PV line -
for them set threshold to 8 instead.

Passed STC
https://tests.stockfishchess.org/tests/view/61b1080406b4c2dcb1b1128c
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 84352 W: 21917 L: 21555 D: 40880 Elo +1.49
Ptnml(0-2): 288, 9524, 22185, 9896, 283

Passed LTC
https://tests.stockfishchess.org/tests/view/61b1860a06b4c2dcb1b134a1
LLR: 2.95 (-2.94,2.94) <0.50,3.00>
Total: 63520 W: 16575 L: 16237 D: 30708 Elo +1.85
Ptnml(0-2): 27, 6519, 18350, 6817, 47

https://github.com/official-stockfish/Stockfish/pull/3840

bench 4729473
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stefan Geschwentner
Date: Wed Dec 8 17:16:17 2021 +0100
Timestamp: 1638980177

Improve transposition table remplacement strategy

Increase chance that PV node replaces old entry in transposition table.

STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.50>
Total: 46744 W: 12108 L: 11816 D: 22820 Elo +2.17
Ptnml(0-2): 156, 5221, 12344, 5477, 174
https://tests.stockfishchess.org/tests/view/61ae068356fcf33bce7d99d0

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 88464 W: 22912 L: 22513 D: 43039 Elo +1.57
Ptnml(0-2): 84, 9133, 25393, 9544, 78
https://tests.stockfishchess.org/tests/view/61ae973656fcf33bce7db3e1

closes https://github.com/official-stockfish/Stockfish/pull/3839

Bench: 5292488
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Tue Dec 7 18:15:06 2021 +0100
Timestamp: 1638897306

Introduce post-lmr extensions

This idea is somewhat similar to extentions in LMR but has a different flavour.
If result of LMR was really good - thus exceeded alpha by some pretty
big given margin, we can extend move after LMR in full depth search with 0 window.
The idea is that this move is probably a fail high with somewhat of a big
probability so extending it makes a lot of sense

passed STC
https://tests.stockfishchess.org/tests/view/61ad45ea56fcf33bce7d74b7
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 59680 W: 15531 L: 15215 D: 28934 Elo +1.84
Ptnml(0-2): 193, 6711, 15734, 6991, 211

passed LTC
https://tests.stockfishchess.org/tests/view/61ad9ff356fcf33bce7d8646
LLR: 2.95 (-2.94,2.94) <0.50,3.00>
Total: 59104 W: 15321 L: 14992 D: 28791 Elo +1.93
Ptnml(0-2): 53, 6023, 17065, 6364, 47

closes https://github.com/official-stockfish/Stockfish/pull/3838

bench 4881329
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Tomasz Sobczyk
Date: Tue Dec 7 18:08:54 2021 +0100
Timestamp: 1638896934

Optimize FT activation and affine transform for NEON.

This patch optimizes the NEON implementation in two ways.

The activation layer after the feature transformer is rewritten to make it easier for the compiler to see through dependencies and unroll. This in itself is a minimal, but a positive improvement. Other architectures could benefit from this too in the future. This is not an algorithmic change.
The affine transform for large matrices (first layer after FT) on NEON now utilizes the same optimized code path as >=SSSE3, which makes the memory accesses more sequential and makes better use of the available registers, which allows for code that has longer dependency chains.

Benchmarks from Redshift#161, profile-build with apple clang

george@Georges-MacBook-Air nets % ./stockfish-b82d93 bench 2>&1 | tail -4 (current master)
===========================
Total time (ms) : 2167
Nodes searched : 4667742
Nodes/second : 2154011
george@Georges-MacBook-Air nets % ./stockfish-7377b8 bench 2>&1 | tail -4 (this patch)
===========================
Total time (ms) : 1842
Nodes searched : 4667742
Nodes/second : 2534061

This is a solid 18% improvement overall, larger in a bench with NNUE-only, not mixed.

Improvement is also observed on armv7-neon (Raspberry Pi, and older phones), around 5% speedup.

No changes for architectures other than NEON.

closes https://github.com/official-stockfish/Stockfish/pull/3837

No functional changes.
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Tue Dec 7 12:40:48 2021 +0100
Timestamp: 1638877248

Update default net to nn-63376713ba63.nnue.

same data set as previous trained nets, tuned the wdl model slightly for training.
https://github.com/vondele/nnue-pytorch/tree/wdlTweak1

passed STC:
https://tests.stockfishchess.org/tests/view/61abe9e456fcf33bce7d2834
LLR: 2.93 (-2.94,2.94) <0.00,2.50>
Total: 31720 W: 8385 L: 8119 D: 15216 Elo +2.91
Ptnml(0-2): 117, 3534, 8273, 3838, 98

passed LTC:
https://tests.stockfishchess.org/tests/view/61ac293756fcf33bce7d36cf
LLR: 2.96 (-2.94,2.94) <0.50,3.00>
Total: 136136 W: 35255 L: 34741 D: 66140 Elo +1.31
Ptnml(0-2): 114, 14217, 38894, 14727, 116

closes https://github.com/official-stockfish/Stockfish/pull/3836

Bench: 4667742
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Mon Dec 6 07:42:04 2021 +0100
Timestamp: 1638772924

Assign extra bonus for previous move that caused a fail low more often

This patch allows to assign extra bonus for previous move that caused a fail low not only for PvNodes and cutNodes but also fo some allNodes - namely if the best result we could've got from the search is still far below alpha.

passed STC
https://tests.stockfishchess.org/tests/view/61aa26a49e8855bba1a36d96
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 73808 W: 19183 L: 18842 D: 35783 Elo +1.61
Ptnml(0-2): 251, 8257, 19564, 8564, 268

passed LTC
https://tests.stockfishchess.org/tests/view/61aa7dc29e8855bba1a3814f
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 142416 W: 36717 L: 36192 D: 69507 Elo +1.28
Ptnml(0-2): 106, 14799, 40862, 15346, 95

closes https://github.com/official-stockfish/Stockfish/pull/3835

bench 4724181
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stefan Geschwentner
Date: Sun Dec 5 18:13:49 2021 +0100
Timestamp: 1638724429

Tweak history initialization

Initialize continuation history with a slighlty negative value -71 instead of zero.

The idea is, because the most history entries will be later negative anyway, to shift
the starting values a little bit in the "correct" direction. Of course the effect of
initialization dimishes with greater depth so I had the apprehension that the LTC test
would be difficult to pass, but it passed.

STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 34520 W: 9076 L: 8803 D: 16641 Elo +2.75
Ptnml(0-2): 136, 3837, 9047, 4098, 142
https://tests.stockfishchess.org/tests/view/61aa52e39e8855bba1a3776b

LTC:
LLR: 2.93 (-2.94,2.94) <0.50,3.00>
Total: 75568 W: 19620 L: 19254 D: 36694 Elo +1.68
Ptnml(0-2): 44, 7773, 21796, 8115, 56
https://tests.stockfishchess.org/tests/view/61aa87d39e8855bba1a383a5

closes https://github.com/official-stockfish/Stockfish/pull/3834

Bench: 4674029
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stefan Geschwentner
Date: Sun Dec 5 17:56:54 2021 +0100
Timestamp: 1638723414

Tweak time management

Use for adjustment of the falling eval time factor now also the difference
between previous best average score and current best score.

STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 109216 W: 28296 L: 27900 D: 53020 Elo +1.26
Ptnml(0-2): 312, 11759, 30148, 11999, 390
https://tests.stockfishchess.org/tests/view/61aafa8d1b31b85bcfa29d9c

LTC:
LLR: 2.93 (-2.94,2.94) <0.50,3.00>
Total: 54096 W: 14091 L: 13787 D: 26218 Elo +1.95
Ptnml(0-2): 29, 5124, 16447, 5410, 38
https://tests.stockfishchess.org/tests/view/61abbbbd56fcf33bce7d1d64

closes https://github.com/official-stockfish/Stockfish/pull/3833

Bench: 4829419
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Sun Dec 5 17:50:04 2021 +0100
Timestamp: 1638723004

Simplifies bestMoveChanges from LMR

As bestMoveChanges is only reset on mainThread and it could change how other
threads search, a multi-threads test was made.

STC:
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 146776 W: 37934 L: 37941 D: 70901 Elo -0.02
Ptnml(0-2): 477, 15644, 41173, 15597, 497
https://tests.stockfishchess.org/tests/view/61a8f9f34ed77d629d4ea2d6

LTC:
LLR: 3.11 (-2.94,2.94) <-2.25,0.25>
Total: 114040 W: 29314 L: 29269 D: 55457 Elo +0.14
Ptnml(0-2): 50, 10584, 35722, 10599, 65
https://tests.stockfishchess.org/tests/view/61a9d4bf9e8855bba1a35c4f

(SMP, 8 threads) STC:
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 23888 W: 6308 L: 6143 D: 11437 Elo +2.40
Ptnml(0-2): 36, 2557, 6600, 2708, 43
https://tests.stockfishchess.org/tests/view/61ac27a756fcf33bce7d3677

closes https://github.com/official-stockfish/Stockfish/pull/3831

bench: 4829419
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Sat Dec 4 10:31:22 2021 +0100
Timestamp: 1638610282

Update default net to nn-cdf1785602d6.nnue

Same process as in https://github.com/official-stockfish/Stockfish/commit/e4a0c6c75950bf27b6dc32490a1102499643126b
with the training started from the current master net.

passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 38224 W: 10023 L: 9742 D: 18459 Elo +2.55
Ptnml(0-2): 133, 4328, 9940, 4547, 164
https://tests.stockfishchess.org/tests/view/61a8611e4ed77d629d4e836e

passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 115176 W: 29783 L: 29321 D: 56072 Elo +1.39
Ptnml(0-2): 68, 12039, 32936, 12453, 92
https://tests.stockfishchess.org/tests/view/61a8963e4ed77d629d4e8d9b

closes https://github.com/official-stockfish/Stockfish/pull/3830

Bench: 4829419
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Fri Dec 3 08:54:46 2021 +0100
Timestamp: 1638518086

Do more aggressive pruning for some node types

This patch allows more aggressive futility/see based pruning for PV nodes with low delta and non-pv nodes.

Fixes some white space issues.

Passed STC
https://tests.stockfishchess.org/tests/view/61a5ed33d16c530b5dcc27cc
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 182088 W: 47121 L: 46584 D: 88383 Elo +1.02
Ptnml(0-2): 551, 20687, 48037, 21212, 557

Passed LTC
https://tests.stockfishchess.org/tests/view/61a74dfdbd5c4360bcded0ac
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 87136 W: 22494 L: 22103 D: 42539 Elo +1.56
Ptnml(0-2): 38, 8918, 25272, 9295, 45

closes https://github.com/official-stockfish/Stockfish/pull/3828
closes https://github.com/official-stockfish/Stockfish/pull/3829

bench 4332259
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Gian-Carlo Pascutto
Date: Fri Dec 3 08:51:06 2021 +0100
Timestamp: 1638517866

Add AVX-VNNI support for Alder Lake and later.

In their infinite wisdom, Intel axed AVX512 from Alder Lake
chips (well, not entirely, but we kind of want to use the Gracemont
cores for chess!) but still added VNNI support.
Confusingly enough, this is not the same as VNNI256 support.

This adds a specific AVX-VNNI target that will use this AVX-VNNI
mode, by prefixing the VNNI instructions with the appropriate VEX
prefix, and avoiding AVX512 usage.

This is about 1% faster on P cores:

Result of 20 runs
==================
base (./clang-bmi2 ) = 3306337 +/- 7519
test (./clang-vnni ) = 3344226 +/- 7388
diff = +37889 +/- 4153

speedup = +0.0115
P(speedup > 0) = 1.0000

But a nice 3% faster on E cores:

Result of 20 runs
==================
base (./clang-bmi2 ) = 1938054 +/- 28257
test (./clang-vnni ) = 1994606 +/- 31756
diff = +56552 +/- 3735

speedup = +0.0292
P(speedup > 0) = 1.0000

This was measured on Clang 13. GCC 11.2 appears to generate
worse code for Alder Lake, though the speedup on the E cores
is similar.

It is possible to run the engine specifically on the P or E using binding,
for example in linux it is possible to use (for an 8 P + 8 E setup like i9-12900K):
taskset -c 0-15 ./stockfish
taskset -c 16-23 ./stockfish
where the first call binds to the P-cores and the second to the E-cores.

closes https://github.com/official-stockfish/Stockfish/pull/3824

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Wed Dec 1 18:22:44 2021 +0100
Timestamp: 1638379364

Correctly reset bestMoveChanges

for searches not using time management (e.g. analysis, fixed node game play etc),
bestMoveChanges was not reset during search iterations. As LMR uses this quantity,
search was somewhat weaker.

Tested using fixed node playing games:
```
./c-chess-cli -each nodes=10000 option.Hash=16 -engine cmd=../Stockfish/src/fix -engine cmd=../Stockfish/src/master -concurrency 6 -openings file=../books/UHO_XXL_+0.90_+1.19.epd -games 10000
Score of Stockfish Fix vs Stockfish Master: 3187 - 3028 - 3785 [0.508] 10000

./c-chess-cli -each nodes=30000 option.Hash=16 -engine cmd=../Stockfish/src/fix -engine cmd=../Stockfish/src/master -concurrency 6 -openings file=../books/UHO_XXL_+0.90_+1.19.epd -games 10000
Score of Stockfish Fix vs Stockfish Master: 2946 - 2834 - 4220 [0.506] 10000
```

closes https://github.com/official-stockfish/Stockfish/pull/3818

bench: 5061979
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Wed Dec 1 18:10:51 2021 +0100
Timestamp: 1638378651

Simplify reduction on rootNode when bestMoveChanges is high

The reduction introduced in #3736 also consider on rootNode, so we don't have to reduce again.

STC:
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 28736 W: 7494 L: 7329 D: 13913 Elo +1.99
Ptnml(0-2): 95, 3247, 7503, 3444, 79
https://tests.stockfishchess.org/tests/view/61a3abe01b7fdf52228e74d8

LTC:
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 47816 W: 12434 L: 12308 D: 23074 Elo +0.92
Ptnml(0-2): 37, 4972, 13755, 5116, 28
https://tests.stockfishchess.org/tests/view/61a3c3e39f0c43dae1c71d71

closes https://github.com/official-stockfish/Stockfish/pull/3817

bench: 6331638
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Ortmann
Date: Wed Dec 1 18:07:30 2021 +0100
Timestamp: 1638378450

Fix typos in comments, adjust readme

closes https://github.com/official-stockfish/Stockfish/pull/3822

also adjusts readme as requested in https://github.com/official-stockfish/Stockfish/pull/3816

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: hengyu
Date: Wed Dec 1 17:59:20 2021 +0100
Timestamp: 1638377960

Small clean-up

remove unneeded calculation.

closes https://github.com/official-stockfish/Stockfish/pull/3807

No functional change.
see source

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