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 22.04.
You can leave a comment.

Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: EntityFX
Date: Tue May 11 19:45:14 2021 +0200
Timestamp: 1620755114

E2K: added support for MCST Elbrus 2000 CPU architecture

e2k (Elbrus 2000) - this is a VLIW/EPIC architecture,
the like Intel Itanium (IA-64) architecture.
The architecture has half native / half software support
for most Intel/AMD SIMD (e.g. MMX/SSE/SSE2/SSE3/SSSE3/SSE4.1/SSE4.2/AES/AVX/AVX2 & 3DNow!/SSE4a/XOP/FMA4) via intrinsics.

https://en.wikipedia.org/wiki/Elbrus_2000

closes https://github.com/official-stockfish/Stockfish/pull/3425

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Tue May 11 19:41:44 2021 +0200
Timestamp: 1620754904

Remove coordination between searching threads

In summary, this revert #2204, as it seems not to bring any strength anymore, so it's no long needed.

STC (5+0.05 @ 8 threads):
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 105728 W: 6406 L: 6393 D: 92929 Elo +0.04
Ptnml(0-2): 154, 5479, 41599, 5464, 168
https://tests.stockfishchess.org/tests/view/6096994095e7f1852abd3154

LTC (20+0.2 @ 8 threads):
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 26336 W: 774 L: 712 D: 24850 Elo +0.82
Ptnml(0-2): 9, 641, 11810, 695, 13
https://tests.stockfishchess.org/tests/view/6097c62995e7f1852abd31e8

closes https://github.com/official-stockfish/Stockfish/pull/3459

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Tue May 11 19:37:39 2021 +0200
Timestamp: 1620754659

Simplify LMR

as it seems not to bring any strength and thus is no longer needed.

Tests for updating elo estimates:
https://tests.stockfishchess.org/tests/view/6099ff123a33eb67a844f789
https://tests.stockfishchess.org/tests/view/60953e6695e7f1852abd305b

Individual simplification tests:
https://tests.stockfishchess.org/tests/view/6098cfc73a33eb67a844f6a1
https://tests.stockfishchess.org/tests/view/6095539495e7f1852abd308b

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 96984 W: 3624 L: 3608 D: 89752 Elo +0.06
Ptnml(0-2): 45, 3222, 41939, 3244, 42
https://tests.stockfishchess.org/tests/view/6099921a3a33eb67a844f74f

closes https://github.com/official-stockfish/Stockfish/pull/3458

bench: 3836428
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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 May 11 19:36:11 2021 +0200
Timestamp: 1620754571

Exporting the currently loaded network file

This PR adds an ability to export any currently loaded network.
The export_net command now takes an optional filename parameter.
If the loaded net is not the embedded net the filename parameter is required.

Two changes were required to support this:

* the "architecture" string, which is really just a some kind of description in the net, is now saved into netDescription on load and correctly saved on export.
* the AffineTransform scrambles weights for some architectures and sparsifies them, such that retrieving the index is hard. This is solved by having a temporary scrambled<->unscrambled index lookup table when loading the network, and the actual index is saved for each individual weight that makes it to canSaturate16. This increases the size of the canSaturate16 entries by 6 bytes.

closes https://github.com/official-stockfish/Stockfish/pull/3456

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Vizvezdenec
Date: Fri May 7 09:47:17 2021 +0200
Timestamp: 1620373637

Cleanup of likelyFailLow logic

This patch broadens and simplifies definition of PvNode that is likely to fail low.
New definition can be described as following "If node was already researched
at depth >= current depth and failed low there" which is more logical than the
previous version and takes less space + allows to not recompute it every time during move loop.

Passed simplification STC
https://tests.stockfishchess.org/tests/view/609148bf95e7f1852abd2e82
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 20128 W: 1865 L: 1751 D: 16512 Elo +1.97
Ptnml(0-2): 63, 1334, 7165, 1430, 72

Passed simplification LTC
https://tests.stockfishchess.org/tests/view/6091691295e7f1852abd2e8b
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 95128 W: 3498 L: 3481 D: 88149 Elo +0.06
Ptnml(0-2): 41, 2956, 41549, 2981, 37

closes https://github.com/official-stockfish/Stockfish/pull/3455

Bench: 3933037
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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: Fri May 7 09:45:08 2021 +0200
Timestamp: 1620373508

Add an UCI level command "export_net".

This command writes the embedded net to the file `EvalFileDefaultName`.
If there is no embedded net the command does nothing.

fixes #3453

closes https://github.com/official-stockfish/Stockfish/pull/3454

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Unai Corzo
Date: Sun May 2 17:48:57 2021 +0200
Timestamp: 1619970537

Simplify check extension

Simplify check extension, as it seems not to bring any strength and thus is no longer needed.

STC https://tests.stockfishchess.org/tests/view/608c18e995e7f1852abd2b81
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 54544 W: 4891 L: 4815 D: 44838 Elo +0.48
Ptnml(0-2): 186, 3889, 19081, 3895, 221

LTC https://tests.stockfishchess.org/tests/view/608c6ab195e7f1852abd2bc6
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 51008 W: 1845 L: 1794 D: 47369 Elo +0.35
Ptnml(0-2): 31, 1591, 22206, 1648, 28

closes https://github.com/official-stockfish/Stockfish/pull/3452

bench: 3993071
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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: Sun May 2 17:43:02 2021 +0200
Timestamp: 1619970182

Add some more information on the UCI protocol

Improve README.md: provide a link to the protocol,
and document some non-standard options.

fixes https://github.com/official-stockfish/Stockfish/issues/3446

closes https://github.com/official-stockfish/Stockfish/pull/3450

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: xoto10
Date: Wed Apr 28 13:58:46 2021 +0200
Timestamp: 1619611126

Change tempo with time and threads

Introduce variable tempo for nnue depending on logarithm of estimated
strength, where strength is the product of time and number of threads.

The original idea here was that NNUE is best with a slightly different
tempo value to classical, since its style of play is slightly different.
It turns out that the best tempo for NNUE varies with strength of play,
so a formula is used which gives about 19 for STC and 24 for LTC under
current fishtest settings.

STC 10+0.1:
LLR: 2.94 (-2.94,2.94) {-0.20,1.10}
Total: 120816 W: 11155 L: 10861 D: 98800 Elo +0.85
Ptnml(0-2): 406, 8728, 41933, 8848, 493
https://tests.stockfishchess.org/tests/view/60735b3a8141753378960534

LTC 60+0.6:
LLR: 2.94 (-2.94,2.94) {0.20,0.90}
Total: 35688 W: 1392 L: 1234 D: 33062 Elo +1.54
Ptnml(0-2): 23, 1079, 15473, 1255, 14
https://tests.stockfishchess.org/tests/view/6073ffbc814175337896057f

Passed non-regression SMP test at LTC 20+0.2 (8 threads):
LLR: 2.95 (-2.94,2.94) {-0.70,0.20}
Total: 11008 W: 317 L: 267 D: 10424 Elo +1.58
Ptnml(0-2): 2, 245, 4962, 291, 4
https://tests.stockfishchess.org/tests/view/60749ea881417533789605a4

closes https://github.com/official-stockfish/Stockfish/pull/3426

Bench 4075325
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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 Apr 28 13:38:28 2021 +0200
Timestamp: 1619609908

Simplify pawn moves generator

This patch simplifies QUIET_CHECKS pawn move generator by merging discovery check
move generator with direct check move generator. It also simplifies emptySquares
instantiation. In addition, I added a comment in generate_moves() to clarify Check
branches.

STC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 112648 W: 9952 L: 9945 D: 92751 Elo +0.02
Ptnml(0-2): 369, 7682, 40195, 7729, 349
https://tests.stockfishchess.org/tests/view/6088226895e7f1852abd2978

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 74656 W: 2797 L: 2765 D: 69094 Elo +0.15
Ptnml(0-2): 38, 2328, 32554, 2380, 28
https://tests.stockfishchess.org/tests/view/60884e5095e7f1852abd2994

closes https://github.com/official-stockfish/Stockfish/pull/3447

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: lonfom169
Date: Sun Apr 25 13:26:22 2021 +0200
Timestamp: 1619349982

More extensions if SE search is very low.

More extensions for non-PV nodes if value from singular extension search is significantly below singularBeta.

Passed STC:
LLR: 2.97 (-2.94,2.94) <-0.50,2.50>
Total: 25064 W: 2334 L: 2162 D: 20568 Elo +2.38
Ptnml(0-2): 82, 1720, 8768, 1868, 94
https://tests.stockfishchess.org/tests/view/6084ba7995e7f1852abd27e3

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 67136 W: 2644 L: 2450 D: 62042 Elo +1.00
Ptnml(0-2): 46, 2134, 28990, 2376, 22
https://tests.stockfishchess.org/tests/view/6084d79195e7f1852abd27ee

closes https://github.com/official-stockfish/Stockfish/pull/3445

Bench: 4075325
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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 Apr 25 13:21:57 2021 +0200
Timestamp: 1619349717

Thread based reduction tweak.

For PV nodes at the first two plies no reductions are done for each fourth thread.

STC (8 threads):
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 53992 W: 3334 L: 3167 D: 47491 Elo +1.07
Ptnml(0-2): 64, 2713, 21285, 2860, 74
https://tests.stockfishchess.org/tests/view/6083b2d695e7f1852abd277a

LTC (8 threads):
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 64888 W: 1888 L: 1725 D: 61275 Elo +0.87
Ptnml(0-2): 14, 1556, 29146, 1709, 19
https://tests.stockfishchess.org/tests/view/6084249595e7f1852abd2795

closes https://github.com/official-stockfish/Stockfish/pull/3443

No functional change (for one thread)
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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: Sun Apr 25 13:16:30 2021 +0200
Timestamp: 1619349390

Cleanup and simplify NNUE code.

A lot of optimizations happend since the NNUE was introduced
and since then some parts of the code were left unused. This
got to the point where asserts were have to be made just to
let people know that modifying something will not have any
effects or may even break everything due to the assumptions
being made. Removing these parts removes those inexisting
"false dependencies". Additionally:

* append_changed_indices now takes the king pos and stateinfo
explicitly, no more misleading pos parameter
* IndexList is removed in favor of a generic ValueList.
Feature transformer just instantiates the type it needs.
* The update cost and refresh requirement is deferred to the
feature set once again, but now doesn't go through the whole
FeatureSet machinery and just calls HalfKP directly.
* accumulator no longer has a singular dimension.
* The PS constants and the PieceSquareIndex array are made local
to the HalfKP feature set because they are specific to it and
DO differ for other feature sets.
* A few names are changed to more descriptive

Passed STC non-regression:
https://tests.stockfishchess.org/tests/view/608421dd95e7f1852abd2790
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 180008 W: 16186 L: 16258 D: 147564 Elo -0.14
Ptnml(0-2): 587, 12593, 63725, 12503, 596

closes https://github.com/official-stockfish/Stockfish/pull/3441

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Sat Apr 24 12:55:33 2021 +0200
Timestamp: 1619261733

Merge all move generators

Merging `generate<EVASIONS>` and `generate<QUIET_CHECKS>` into `generate_all()`.

verified to yield correct perft results, even though bench changes due to different order of generated moves.

No regresion playing games:

passed STC:
LLR: 2.94 (-2.94,2.94) {-1.00,0.20}
Total: 161800 W: 14585 L: 14624 D: 132591 Elo -0.08
Ptnml(0-2): 577, 11681, 56451, 11586, 605
https://tests.stockfishchess.org/tests/view/606532732b2df919fd5f026d

passed LTC:
LLR: 2.98 (-2.94,2.94) {-0.70,0.20}
Total: 188504 W: 6906 L: 6961 D: 174637 Elo -0.10
Ptnml(0-2): 87, 6272, 81610, 6175, 108
https://tests.stockfishchess.org/tests/view/6065b0772b2df919fd5f02ae

closes https://github.com/official-stockfish/Stockfish/pull/3418

Bench: 4536129
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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: Sat Apr 24 12:49:29 2021 +0200
Timestamp: 1619261369

Unify naming convention of the NNUE code

matches the rest of the stockfish code base

closes https://github.com/official-stockfish/Stockfish/pull/3437

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: dsmsgms
Date: Thu Apr 15 12:45:39 2021 +0200
Timestamp: 1618483539

Use classical eval for Bishop vs Pawns

NNUE evaluation is incapable of recognizing trivially drawn bishop endgames
(the wrong-colored rook pawn), which are in fact ubiquitous and stock standard
in chess analysis. Switching off NNUE evaluation in KBPs vs KPs endgames is
a measure that stops Stockfish from trading down to a drawn version of these
endings when we presumably have advantage. The patch is able to edge over master
in endgame positions.

Patch tested for Elo gain with the "endgame.epd" book, and verified for
non-regression with our usual book (see the pull request for details).

STC:
LLR: 2.93 (-2.94,2.94) {-0.20,1.10}
Total: 33232 W: 6655 L: 6497 D: 20080 Elo +1.65
Ptnml(0-2): 4, 2342, 11769, 2494, 7
https://tests.stockfishchess.org/tests/view/6074a52981417533789605b8

LTC:
LLR: 2.93 (-2.94,2.94) {0.20,0.90}
Total: 159056 W: 29799 L: 29378 D: 99879 Elo +0.92
Ptnml(0-2): 7, 9004, 61085, 9425, 7
https://tests.stockfishchess.org/tests/view/6074c39a81417533789605ca

Closes https://github.com/official-stockfish/Stockfish/pull/3427

Bench: 4503918

blah
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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: Thu Apr 15 12:21:30 2021 +0200
Timestamp: 1618482090

Documentation patch: AppendChangedIndices

Clarify the assumptions on the position passed to the AppendChangedIndices().

Closes https://github.com/official-stockfish/Stockfish/pull/3428

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Vizvezdenec
Date: Thu Apr 15 11:41:30 2021 +0200
Timestamp: 1618479690

Simplification: last capture extension

The code for last capture extension can be removed in current master.

Passed STC
LLR: 2.95 (-2.94,2.94) {-1.00,0.20}
Total: 85024 W: 7754 L: 7707 D: 69563 Elo +0.19
Ptnml(0-2): 293, 5991, 29914, 6004, 310
https://tests.stockfishchess.org/tests/view/607690f1814175337896068f

Passed LTC
LLR: 2.96 (-2.94,2.94) {-0.70,0.20}
Total: 39880 W: 1503 L: 1453 D: 36924 Elo +0.44
Ptnml(0-2): 17, 1281, 17293, 1333, 16
https://tests.stockfishchess.org/tests/view/6076ccbe814175337896069e

Closes https://github.com/official-stockfish/Stockfish/pull/3430

Bench: 4202264
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stéphane Nicolet
Date: Thu Apr 15 11:19:44 2021 +0200
Timestamp: 1618478384

Revert previous patch

Revert the previous patch about move generation, as it unexpectedly
changed the bench. Better to take the time to understand the issue.

Bench: 4191632
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: bmc4
Date: Thu Apr 15 10:53:51 2021 +0200
Timestamp: 1618476831

Merge all move generators

Merging `generate<EVASIONS>` and `generate<QUIET_CHECKS>` into `generate_all()`.

STC:
LLR: 2.94 (-2.94,2.94) {-1.00,0.20}
Total: 161800 W: 14585 L: 14624 D: 132591 Elo -0.08
Ptnml(0-2): 577, 11681, 56451, 11586, 605
https://tests.stockfishchess.org/tests/view/606532732b2df919fd5f026d

LTC:
LLR: 2.98 (-2.94,2.94) {-0.70,0.20}
Total: 188504 W: 6906 L: 6961 D: 174637 Elo -0.10
Ptnml(0-2): 87, 6272, 81610, 6175, 108
https://tests.stockfishchess.org/tests/view/6065b0772b2df919fd5f02ae

------------

Verified for correctness of `EVASIONS` by running perft:
```
./stockfish b3nch 16 1 6 default perft (replace 3 by e in b3nch)
Nodes searched : 71608931810
```

Also tested for correctness on Chess960 with a similar code shown here:
https://github.com/official-stockfish/Stockfish/pull/3418#issuecomment-816630295

```
./stockfish b3nch 16 1 6 fischer.txt perft
Nodes searched : 506736009395
```

------------

Closes https://github.com/official-stockfish/Stockfish/pull/3418

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Vizvezdenec
Date: Tue Apr 6 18:23:35 2021 +0200
Timestamp: 1617726215

Replace distanceFromPv with a better logic

This patch removes the recently introduced distanceFromPv logic, and replaces
it with following logic: if reduction of moves with low movecount is really
negative, we search them deeper than the first move.

passed STC:
LLR: 2.95 (-2.94,2.94) {-0.20,1.10}
Total: 153008 W: 13913 L: 13579 D: 125516 Elo +0.76
Ptnml(0-2): 547, 10811, 53470, 11113, 563
https://tests.stockfishchess.org/tests/view/6069c9d02b2df919fd5f04d2

passed LTC:
LLR: 2.94 (-2.94,2.94) {0.20,0.90}
Total: 101920 W: 3964 L: 3699 D: 94257 Elo +0.90
Ptnml(0-2): 55, 3279, 44019, 3560, 47
https://tests.stockfishchess.org/tests/view/606a99fd2b2df919fd5f0532

Closes https://github.com/official-stockfish/Stockfish/pull/3421

Bench: 4191632
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stéphane Nicolet
Date: Tue Apr 6 09:07:20 2021 +0200
Timestamp: 1617692840

Keep more pawns

This patch increases the weight of pawns in the scale factor applied
to the output of the NNUE evaluation. This has the effect that Stockfish
will try a little bit harder to keep more pawns in position where the
engine has the advantage, and exchange more pawns in bad positions.

STC:
LLR: 2.93 (-2.94,2.94) {-0.20,1.10}
Total: 42552 W: 3858 L: 3668 D: 35026 Elo +1.55
Ptnml(0-2): 152, 2956, 14876, 3134, 158
https://tests.stockfishchess.org/tests/view/606a06dd2b2df919fd5f0504

LTC:
LLR: 2.95 (-2.94,2.94) {0.20,0.90}
Total: 44328 W: 1703 L: 1531 D: 41094 Elo +1.35
Ptnml(0-2): 20, 1373, 19207, 1543, 21
https://tests.stockfishchess.org/tests/view/606aa4ec2b2df919fd5f053e

Closes https://github.com/official-stockfish/Stockfish/pull/3420

Bench: 4310076
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stéphane Nicolet
Date: Wed Mar 31 08:12:25 2021 +0200
Timestamp: 1617171145

Small clean-up

Bench: 4321677
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Windows 32
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 Mar 31 07:47:15 2021 +0200
Timestamp: 1617169635

Simplify King Evasion

Simplify away the removal of some illegal `KING`-evasion moves during move
generation. Verified for correctness by running perft on the following positions:

```
./stockfish
bench 16 1 6 default perft
Nodes searched: 71608931810

./stockfish
position fen 4rrk1/1p1nq3/p7/2p1P1pp/3P2bp/3Q1Bn1/PPPB4/1K2R1NR w - - 40 21
go perft 6
Nodes searched: 6136386434
```

Passed STC:
LLR: 2.94 (-2.94,2.94) {-1.00,0.20}
Total: 16072 W: 1473 L: 1349 D: 13250 Elo +2.68
Ptnml(0-2): 57, 1047, 5710, 1159, 63
https://tests.stockfishchess.org/tests/view/60629e7ef183b42957b423b1

Passed LTC:
LLR: 2.94 (-2.94,2.94) {-0.70,0.20}
Total: 59064 W: 2214 L: 2177 D: 54673 Elo +0.22
Ptnml(0-2): 26, 1944, 25556, 1979, 27
https://tests.stockfishchess.org/tests/view/6062dce4f183b42957b423de

closes https://github.com/official-stockfish/Stockfish/pull/3415

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
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: mstembera
Date: Sat Mar 27 17:03:10 2021 +0100
Timestamp: 1616860990

Simplify and unify FRC cornered bishop.

tested locally as fishtest doesn't support FRC:

STC NNUE
9646 - 9647 - 20707 [0.500] 40000 -0.0 +/- 2.4, LOS: 49.7 %, DrawRatio: 51.8 %

STC classical
9678 - 9609 - 20713 [0.501] 40000 0.6 +/- 2.4, LOS: 69.0 %, DrawRatio: 51.8 %

and verified independently:

Score of master vs patch: 6463 - 6580 - 34957 [0.499] 48000

closes https://github.com/official-stockfish/Stockfish/pull/3413

bench: 4321677
see source

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