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Author SHA1 Message Date
Daniel MonroeandJoost VandeVondele 9e071f3561 Simplify best move effort 
Passed non-regression STC
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 44224 W: 11614 L: 11403 D: 21207
Ptnml(0-2): 147, 4936, 11726, 5165, 138
https://tests.stockfishchess.org/tests/view/68e9410ed323fd15c04e3a87

Passed non-regression LTC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 109788 W: 28223 L: 28096 D: 53469
Ptnml(0-2): 60, 11493, 31657, 11628, 56
https://tests.stockfishchess.org/tests/view/68eb5ac0a23744016c14af1d

closes https://github.com/official-stockfish/Stockfish/pull/6371

No functional change
 2025-11-01 11:18:00 +01:00
Carlos EsparzaandJoost VandeVondele 11ab4cde07 Avoid unnecessary allocations in AccumulatorStack 
replacing the vector with an array resulted in a .45+-.10 % speedup.

closes https://github.com/official-stockfish/Stockfish/pull/6352

no functional change
 2025-11-01 11:12:03 +01:00
pb00067andJoost VandeVondele fa3b4ef5af Improve retrograde analisys and matefinding capability 
fixes https://github.com/official-stockfish/Stockfish/issues/6328

Before calling search(depth), the patch ensures that depth is at least 1
whenever we encounter a decisive score in the transposition table (TT). This
prevents search(depth) from being executed by qsearch, which would otherwise
ignore that information.  Typically, decisive TT hits occur when analyzing a
mating sequence backward. Due to the nature of Iterative Deepening (IID), such
scores are usually first found at depth 0. Without this patch, valuable
information can be lost because qsearch may overwrite the TT entry by replacing
the value with a static evaluation, even though the node was already processed
at a higher depth. This is also why the engine sometimes loses track of an
already discovered mate.

Using ..\sf\patch.exe on matetrack.epd with --nodes 1000000
Engine ID:     Stockfish dev-20251015-nogit
Total FENs:    6554
Found mates:   3437
Best mates:    2438

Using ..\sf\master.exe on matetrack.epd with --nodes 1000000
Engine ID:     Stockfish dev-20251015-nogit
Total FENs:    6554
Found mates:   3337
Best mates:    2407

Passed STC
https://tests.stockfishchess.org/tests/view/68fa3fa7637acd2a11e72a79
LLR: 3.55 (-2.94,2.94) <0.00,2.00>
Total: 134144 W: 34960 L: 34471 D: 64713
Ptnml(0-2): 376, 14199, 37459, 14636, 402

Failed LTC
https://tests.stockfishchess.org/tests/view/68ffc1b5637acd2a11e73377
LLR: -3.10 (-2.94,2.94) <0.50,2.50>
Total: 75360 W: 19423 L: 19519 D: 36418
Ptnml(0-2): 38, 7553, 22605, 7435, 49

closes https://github.com/official-stockfish/Stockfish/pull/6386

bench: 2530552
 2025-11-01 11:02:00 +01:00
shaowyxandJoost VandeVondele a49b52cf69 Revert malus and associated coefficient parameters resulting from using only quiet moves 
Following #6226 and #6256, this patch ultimately corresponds to the revert of #6200.
Parameters were tuned on 60k LTC games.

STC (10+0.1 th1) was accepted:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 167488 W: 43573 L: 43063 D: 80852
Ptnml(0-2): 506, 19644, 43004, 20014, 576
https://tests.stockfishchess.org/tests/view/68f526a4637acd2a11e721c2

LTC (60+0.6 th1) was accepted:
LLR: 2.99 (-2.94,2.94) <0.50,2.50>
Total: 61068 W: 15882 L: 15510 D: 29676
Ptnml(0-2): 31, 6578, 16949, 6940, 36
https://tests.stockfishchess.org/tests/view/68fa1968637acd2a11e72a0a

Non-regression VLTC (180+1.8 th1) was accepted:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 50380 W: 13087 L: 12905 D: 24388
Ptnml(0-2): 5, 5018, 14962, 5200, 5
https://tests.stockfishchess.org/tests/view/68fdc6e5637acd2a11e72f33

closes https://github.com/official-stockfish/Stockfish/pull/6378

Bench: 2530552
 2025-11-01 10:48:40 +01:00
Timothy HerchenandJoost VandeVondele 6764561916 Improve index generation 
The speedup seems to vary by machine.  The indexing function can be changed w/o needing to understand intrinsics.

Result of 100 runs
==================
base (...ish_baseline) =    1719637  +/- 3233
test (./stockfish    ) =    1734245  +/- 3534
diff                   =     +14608  +/- 4868

speedup        = +0.0085
P(speedup > 0) =  1.0000

closes https://github.com/official-stockfish/Stockfish/pull/6366

No functional change
 2025-11-01 10:42:42 +01:00
Timothy HerchenandJoost VandeVondele 3bb01ce7a9 prefetch earlier if checKEP is false 
Only a modest amount of work happens between the transposition table prefetch
and the probe, so the probe still often stalls waiting for DRAM. The vast
majority of the time (in particular, if !checkEP), the key is known much
earlier in the do_move function and the latency can be better hidden.

passed STC SMP
https://tests.stockfishchess.org/tests/view/68f337c528e6d77fcffa066a
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 65256 W: 16806 L: 16462 D: 31988
Ptnml(0-2): 76, 7386, 17362, 7726, 78

but failed to gain STC
https://tests.stockfishchess.org/tests/view/68f3378328e6d77fcffa0665
LLR: -2.94 (-2.94,2.94) <0.00,2.00>
Total: 109824 W: 28523 L: 28618 D: 52683
Ptnml(0-2): 311, 11799, 30788, 11702, 312

In local tests, the speedup grows with thread count

closes https://github.com/official-stockfish/Stockfish/pull/6372

No functional change
 2025-11-01 10:40:23 +01:00
Shawn XuandJoost VandeVondele f434cc2918 Allow AccumulatorStack::size to point to one past the end 
this is guaranteed to be correct since we access the last element with `size - 1`

closes https://github.com/official-stockfish/Stockfish/pull/6368

fixes https://github.com/official-stockfish/Stockfish/issues/6367

no functional change
 2025-11-01 10:34:44 +01:00
Taras VukandJoost VandeVondele b9e3e7921b Increase NMP reduction when improving 
Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 52896 W: 13904 L: 13565 D: 25427
Ptnml(0-2): 186, 6022, 13706, 6335, 199
https://tests.stockfishchess.org/tests/view/68e67d02a017f472e763dfaf

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 168354 W: 43750 L: 43163 D: 81441
Ptnml(0-2): 81, 18284, 46882, 18827, 103
https://tests.stockfishchess.org/tests/view/68e79d7ba017f472e763e352

closes https://github.com/official-stockfish/Stockfish/pull/6361

bench: 2537382
 2025-11-01 10:28:02 +01:00
Kieren PearsonandJoost VandeVondele 75edbee01e Use huge pages for worker data 
As the worker data is quite large (28MB after #6350) we can make use of huge pages as a speedup.

prior to #6350

STC passed elo gaining bounds:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 166272 W: 43479 L: 42993 D: 79800
Ptnml(0-2): 540, 17598, 46365, 18102, 531
https://tests.stockfishchess.org/tests/view/68e9f3c0d323fd15c04e3ba4

Tested the speedup on a large machine with speedtest:
==== master ====
Average (over 20):  288644510
==== largePageWorker ====
Average (over 20):  292082422

Test after #6350:
==== rustam-cpp-testPR ====
Average (over 20):  291035351
==== rustam-cpp-testPR-pages ====
Average (over 20):  291937367

https://github.com/official-stockfish/Stockfish/pull/6359

No functional change
 2025-10-14 17:46:13 +02:00
Robert Nurnberg @ elitebookandJoost VandeVondele 315f8ba4bf let CI check for mate scores outside the valid range 
closes https://github.com/official-stockfish/Stockfish/pull/6358

No functional change
 2025-10-14 17:34:17 +02:00
Daniel MonroeandJoost VandeVondele e7a4708ad5 Remove condition in qsearch 
Instead of skipping non-captures when pawn history is exceptionally high, skip all non-captures

Passed non-regression STC
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 38016 W: 10018 L: 9795 D: 18203
Ptnml(0-2): 155, 4346, 9755, 4625, 127
https://tests.stockfishchess.org/tests/view/68e43d4aa017f472e763db2e

Passed rebased non-regression LTC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 96048 W: 24854 L: 24710 D: 46484
Ptnml(0-2): 47, 10504, 26780, 10644, 49
https://tests.stockfishchess.org/tests/view/68e59352a017f472e763dcf9

closes https://github.com/official-stockfish/Stockfish/pull/6355

bench 2343840
 2025-10-14 17:32:32 +02:00
rustam-cppandJoost VandeVondele 63d449d1d9 bigger PAWN_HISTORY_SIZE 
STC (10+0.1 th1) was accepted:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 75712 W: 19701 L: 19326 D: 36685
Ptnml(0-2): 254, 8738, 19513, 9081, 270
https://tests.stockfishchess.org/tests/view/68e286d5fa806e2e8393d160

LTC (60+0.6 th1) was accepted:
LLR: 2.96 (-2.94,2.94) <0.50,2.50>
Total: 108492 W: 28068 L: 27604 D: 52820
Ptnml(0-2): 60, 11639, 30390, 12091, 66
https://tests.stockfishchess.org/tests/view/68e3e564a017f472e763dac0

closes https://github.com/official-stockfish/Stockfish/pull/6350

bench 2128316
 2025-10-14 17:27:42 +02:00
mstemberaandJoost VandeVondele c956df4cbb Split accumulator 3-way for avxvnni 
This does the same thing for x86-64-avxvnni as #6336, #6339.

closes https://github.com/official-stockfish/Stockfish/pull/6347

No functional change
 2025-10-14 17:25:48 +02:00
dav1312andJoost VandeVondele fc5d296f9d Update get_native_properties.sh for AVXVNNI 
Update get_native_properties.sh to detect and report 'x86-64-avxvnni' when the CPU supports it.

closes https://github.com/official-stockfish/Stockfish/pull/6346

No functional change
 2025-10-14 17:22:30 +02:00
Daniel SamekandJoost VandeVondele e18ed795f2 Introduce 4-ply continuation correction history 
Passed STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 113984 W: 29752 L: 29323 D: 54909
Ptnml(0-2): 376, 13191, 29435, 13608, 382
https://tests.stockfishchess.org/tests/view/68dc3576fa806e2e8393bd93

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 80154 W: 20823 L: 20417 D: 38914
Ptnml(0-2): 47, 8600, 22383, 8994, 53
https://tests.stockfishchess.org/tests/view/68df83e0fa806e2e8393cbe8

Passed non-regression VLTC (rebased):
LLR: 2.98 (-2.94,2.94) <-1.75,0.25>
Total: 38158 W: 9992 L: 9805 D: 18361
Ptnml(0-2): 3, 3406, 12075, 3591, 4
https://tests.stockfishchess.org/tests/view/68e22f2afa806e2e8393d0ed

closes https://github.com/official-stockfish/Stockfish/pull/6345

bench 2169281
 2025-10-07 11:50:51 +02:00
Daniel MonroeandJoost VandeVondele feb17e5acf Make sure we don't move a nonexistent piece in SEE 
added assert.

closes https://github.com/official-stockfish/Stockfish/pull/6342

No functional change
 2025-10-07 11:49:00 +02:00
mstemberaandJoost VandeVondele ee243f0fdc Remove x86-64-vnni256 target 
When vnni256 was first introduced #3038 it was very slightly faster than vnni512
on some machines. We have since sped up vnni512 significantly (#4796 over 10%
alone, #6139, and probably others I'm forgetting). Since any machine that can
run vnni256 can run vnni512 this arch is no longer useful.

Note, x86-64-avxvnni still covers targets that don't have AVX512 but do have
VNNI on 128- and 256-bit vectors.

closes https://github.com/official-stockfish/Stockfish/pull/6340

No functional change
 2025-10-05 09:38:44 +02:00
Shawn XuandJoost VandeVondele e5c2dc5edd remove clang-format workaround 
closes https://github.com/official-stockfish/Stockfish/pull/6332

No functional change
 2025-10-05 09:33:42 +02:00
Timothy HerchenJoost VandeVondeleM Stembera
 		b09339a420 Split accumulator 3-Way 
Squeeze a tiny bit more juice from the original idea in #6336 which this is on top of.

https://tests.stockfishchess.org/tests/view/68dddd85fa806e2e8393c0b9
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 156320 W: 40925 L: 40447 D: 74948
Ptnml(0-2): 427, 17330, 42172, 17800, 431

4-way doesn't look to be better than this.
https://tests.stockfishchess.org/tests/view/68dde19efa806e2e8393c0c1

closes https://github.com/official-stockfish/Stockfish/pull/6339

No functional change

Co-authored-by: M Stembera <m_stembera@yahoo.com>
 2025-10-05 09:33:23 +02:00
FauziAkramandJoost VandeVondele 7a7c033a86 Tweak Correction History Bonus Asymmetrically 
Refine the correction history update by applying an asymmetric bonus based on the type of evaluation error. It differentiates between negative corrections and positive corrections.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 165184 W: 43314 L: 42807 D: 79063
Ptnml(0-2): 551, 19391, 42261, 19778, 611
https://tests.stockfishchess.org/tests/view/68cae49902c43c969fe7f008

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 243234 W: 62765 L: 62029 D: 118440
Ptnml(0-2): 163, 25996, 68551, 26756, 151
https://tests.stockfishchess.org/tests/view/68d1c50dfa806e2e8393aa1f

closes https://github.com/official-stockfish/Stockfish/pull/6338

Bench: 2746404
 2025-10-05 09:25:44 +02:00
nicolasduhamelandJoost VandeVondele 5c93616a3f Adjust aspiration window 
Narrow the aspiration window after fail high.

Passed STC:
LLR: 2.98 (-2.94,2.94) <0.00,2.00>
Total: 51296 W: 13550 L: 13207 D: 24539
Ptnml(0-2): 165, 5971, 13052, 6276, 184
https://tests.stockfishchess.org/tests/view/68d99afffa806e2e8393b7ae

Passed LTC;
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 87780 W: 22795 L: 22375 D: 42610
Ptnml(0-2): 52, 9340, 24694, 9744, 60
https://tests.stockfishchess.org/tests/view/68dae0a6fa806e2e8393baad

See the comments in #6293 discussing the mechanisms leading to issue #6296

closes https://github.com/official-stockfish/Stockfish/pull/6337

Bench: 2336606
 2025-10-05 09:23:02 +02:00
Shawn XuandJoost VandeVondele 5895f47dab Further simplify low ply history in evasions 
Passed Non-regression STC (vs #6308):
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 174208 W: 45414 L: 45343 D: 83451
Ptnml(0-2): 633, 20324, 45095, 20443, 609
https://tests.stockfishchess.org/tests/view/68c24be359efc3c96b611487

Passed Non-regression LTC (vs #6308):
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 110070 W: 28099 L: 27969 D: 54002
Ptnml(0-2): 56, 11919, 30962, 12035, 63
https://tests.stockfishchess.org/tests/view/68c4efa559efc3c96b611dfc

closes https://github.com/official-stockfish/Stockfish/pull/6321

Bench: 2151873
 2025-10-05 09:18:16 +02:00
Shawn XuandJoost VandeVondele 3073d82ccf Simplify use of low-ply history in evasions 
Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 65024 W: 16991 L: 16804 D: 31229
Ptnml(0-2): 182, 7423, 17119, 7602, 186
https://tests.stockfishchess.org/tests/view/68c23f5459efc3c96b6113df

Passed Non-regression LTC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 207312 W: 53126 L: 53095 D: 101091
Ptnml(0-2): 126, 21986, 59389, 22041, 114
https://tests.stockfishchess.org/tests/view/68c241e359efc3c96b6113ef

closes https://github.com/official-stockfish/Stockfish/pull/6308

Bench: 2515619
 2025-09-28 21:21:57 +02:00
Shawn XuandJoost VandeVondele c62e71e78f Simplify a separate term in low ply history bonus formula 
Passed Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 211200 W: 54887 L: 54860 D: 101453
Ptnml(0-2): 719, 24894, 54296, 25023, 668
https://tests.stockfishchess.org/tests/view/68c21e7f59efc3c96b6112c8

Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 217842 W: 55587 L: 55568 D: 106687
Ptnml(0-2): 130, 23651, 61313, 23724, 103
https://tests.stockfishchess.org/tests/view/68c230ec59efc3c96b61135a

closes https://github.com/official-stockfish/Stockfish/pull/6307

Bench: 2070860
 2025-09-28 21:19:22 +02:00
FauziAkramandJoost VandeVondele 40aeb5a411 Simplify away conthist 0 
While at it, I also added the scaler note to the Lmrdepth/history formula.

Passed STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 25376 W: 6660 L: 6423 D: 12293
Ptnml(0-2): 77, 2947, 6403, 3184, 77
https://tests.stockfishchess.org/tests/view/68c1ccf759efc3c96b610deb

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 208464 W: 53371 L: 53342 D: 101751
Ptnml(0-2): 110, 22776, 58426, 22815, 105
https://tests.stockfishchess.org/tests/view/68c1d04b59efc3c96b610e13

closes https://github.com/official-stockfish/Stockfish/pull/6304

Bench: 2029296
 2025-09-28 21:14:28 +02:00
Shawn XuandJoost VandeVondele 415a1ad426 Simplify Probcut Clamp Further 
Passed Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 157984 W: 41116 L: 41030 D: 75838
Ptnml(0-2): 568, 18570, 40601, 18714, 539
https://tests.stockfishchess.org/tests/view/68b750518f94a4e5a7fe76cd

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 335232 W: 85443 L: 85543 D: 164246
Ptnml(0-2): 177, 36616, 94137, 36502, 184
https://tests.stockfishchess.org/tests/view/68bc767259efc3c96b61076b

closes https://github.com/official-stockfish/Stockfish/pull/6303

Bench: 2213844
 2025-09-28 21:12:01 +02:00
Shawn XuJoost VandeVondeleDaniel Monroe
 		7a36c0e95f Remove quiet move streak 
Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 67712 W: 17744 L: 17555 D: 32413
Ptnml(0-2): 204, 8030, 17274, 8069, 279
https://tests.stockfishchess.org/tests/view/68b784628f94a4e5a7fe7706

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 196050 W: 50270 L: 50228 D: 95552
Ptnml(0-2): 122, 21465, 54813, 21499, 126
https://tests.stockfishchess.org/tests/view/68ba119d8f94a4e5a7fe7941

closes https://github.com/official-stockfish/Stockfish/pull/6299

Bench: 2238789

Co-authored-by: Daniel Monroe <github.com@danielmonroe.net>
 2025-09-28 21:08:58 +02:00
Timothy HerchenandJoost VandeVondele 9b164d9520 Shave some instructions off a hot loop in affine transform 
On x86, GCC generates highly suboptimal code for this loop in its old form,
about 2x as many instructions as necessary. This decreases throughput
especially in an SMT setting. Clang does a better job but this change still has
some improvement. Note that the std::ptrdiff_t type is not optional; using an
unsigned type brings back the bad assembly. (Not sure why, but it seems
reliable on all the GCC versions I tested.)

passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 44672 W: 11841 L: 11527 D: 21304
Ptnml(0-2): 165, 4625, 12415, 4993, 138
https://tests.stockfishchess.org/tests/view/68d8111efa806e2e8393b10e

closes https://github.com/official-stockfish/Stockfish/pull/6331

No functional change
 2025-09-28 21:04:29 +02:00
Michael ChalyandJoost VandeVondele 4f4f78f86e Extend nodes pre qsearch only with deep enough tt entries 
Modification of current pre qsearch extensions - allowing it only for deep enough tt entries.

Passed STC:
https://tests.stockfishchess.org/tests/view/68c954d302c43c969fe7eea5
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 35872 W: 9548 L: 9236 D: 17088
Ptnml(0-2): 101, 4075, 9295, 4341, 124

Passed LTC:
https://tests.stockfishchess.org/tests/view/68ca4e4f02c43c969fe7ef5f
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 107754 W: 27784 L: 27324 D: 52646
Ptnml(0-2): 47, 11528, 30300, 11922, 80

closes https://github.com/official-stockfish/Stockfish/pull/6324

bench: 2462792
 2025-09-28 20:56:36 +02:00
Nonlinear2andJoost VandeVondele 6fa42d9724 Simplify RFP return value 
Passed non-regression STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 220800 W: 57351 L: 57332 D: 106117
Ptnml(0-2): 726, 26200, 56548, 26181, 745
https://tests.stockfishchess.org/tests/view/68b1db6e6217b8721dca9c67

Passed gainer LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 257820 W: 66286 L: 65523 D: 126011
Ptnml(0-2): 118, 27586, 72779, 28269, 158
https://tests.stockfishchess.org/tests/view/68c1d40859efc3c96b610e3d

closes https://github.com/official-stockfish/Stockfish/pull/6310

bench: 2364596
 2025-09-28 20:53:47 +02:00
FauziAkramandJoost VandeVondele bbad001a49 Double PawnHistory size and update formula 
Doubling PAWN_HISTORY_SIZE to 1024. So with that, we can apply a stronger learning signal.
The bonus/malus multipliers in the update_quiet_histories function have been increased accordingly.

Passed STC:
LLR: 2.97 (-2.94,2.94) <0.00,2.00>
Total: 111008 W: 29136 L: 28708 D: 53164
Ptnml(0-2): 367, 12870, 28609, 13284, 374
https://tests.stockfishchess.org/tests/view/68c201d659efc3c96b61117e

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 117210 W: 30142 L: 29664 D: 57404
Ptnml(0-2): 49, 12532, 32970, 13000, 54
https://tests.stockfishchess.org/tests/view/68c20a6259efc3c96b6111ef

closes https://github.com/official-stockfish/Stockfish/pull/6306

Bench: 2788334
 2025-09-28 20:51:34 +02:00
Syine MinetaandJoost VandeVondele a47a1c1804 Penalty to TT move history on MultiCut 
If a reduced search fails high with the TT move excluded, we know that
there are multiple moves that can produce cutoffs. Applying a  penalty
to the TT move history reduces extensions for TT moves so that it may
spend a bit more time exploring other moves.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 263680 W: 68965 L: 68313 D: 126402
Ptnml(0-2): 855, 31090, 67336, 31666, 893
https://tests.stockfishchess.org/tests/view/68c1f65a59efc3c96b6110e5

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 61008 W: 15713 L: 15350 D: 29945
Ptnml(0-2): 27, 6428, 17235, 6783, 31
https://tests.stockfishchess.org/tests/view/68c1fc5359efc3c96b611141

Passed non-regression VLTC (60+0.6, Threads=8):
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 50340 W: 13003 L: 12830 D: 24507
Ptnml(0-2): 3, 4570, 15849, 4747, 1
https://tests.stockfishchess.org/tests/view/68c2056559efc3c96b6111c3

closes https://github.com/official-stockfish/Stockfish/pull/6305

Bench: 2342975
 2025-09-28 20:49:24 +02:00
Sebastian BuchwaldandJoost VandeVondele a82e2a4cb6 Replace deprecated macOS 13 runner image 
The macOS 13 runner image will be retired by December 4th, 2025.

closes https://github.com/official-stockfish/Stockfish/pull/6330

No functional change
 2025-09-28 20:46:42 +02:00
Robert Nurnberg @ elitebookandJoost VandeVondele f922fb5d55 add multithreaded matetrack runs to CI 
Add runs with --threads 4 to our matetrack CI. These won't be deterministic, of
course. But they may catch early some multithreading bugs in our mate
reporting.

Motivated by #6293 and #6296.

https://github.com/official-stockfish/Stockfish/pull/6297

No functional change.
 2025-09-28 20:45:30 +02:00
DisservinandJoost VandeVondele 1a3a9c9005 simplify upload_binaries ci 
Previously the upload step used the os of the artifact to create the upload and
used an extra msys2 step. This is in fact not needed and we can do all required
changes on ubuntu instead.

closes https://github.com/official-stockfish/Stockfish/pull/6294

No functional change
 2025-09-28 20:43:54 +02:00
Syine MinetaandJoost VandeVondele fc54d87301 Revert "Adjustment of the aspiration window after fail high/low." 
This reverts commit bfc7000597.

Fixes https://github.com/official-stockfish/Stockfish/issues/6296

After this commit a bug has been reported when the position is close to
mate or being mated. Since no workarounds have been suggested yet, it
is best to revert this commit until a better solution is found.

closes https://github.com/official-stockfish/Stockfish/pull/6309

Bench: 2493363
 2025-09-13 08:18:52 +02:00
Stefan GeschwentnerandJoost VandeVondele bfc7000597 Adjustment of the aspiration window after fail high/low. 
For the new bound in the opposite direction of the fail, use a weighted average of alpha, beta and best value +- delta. In the case of a fail high, different average weights are used depending on whether or not there was a best move change during the last search.

The weights are determined from the following two consecutive LTC tunings.

First tuning: https://tests.stockfishchess.org/tests/view/68ab727975da51a345a5ac2e
Second tuning: https://tests.stockfishchess.org/tests/view/68aba3fe75da51a345a5ad52

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 39504 W: 10243 L: 9947 D: 19314
Ptnml(0-2): 25, 4182, 11041, 4480, 24
https://tests.stockfishchess.org/tests/view/68acbb6d6217b8721dca95f8

Passed VLTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 91196 W: 23574 L: 23167 D: 44455
Ptnml(0-2): 13, 8943, 27276, 9356, 10
https://tests.stockfishchess.org/tests/view/68af64786217b8721dca993d

closes https://github.com/official-stockfish/Stockfish/pull/6292

Bench: 2785713
 2025-09-06 07:57:57 +02:00
Shawn XuandJoost VandeVondele d5f152b5df Reintroduce #6259 
Reintroduces af181d9, which no longer regresses on matetrack after #6286

Using ./stockfish on matetrack.epd with --nodes 1000000
Engine ID:     Stockfish dev-20250902-adfddd2c
Total FENs:    6554
Found mates:   3490
Best mates:    2429

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 37608 W: 9726 L: 9523 D: 18359
Ptnml(0-2): 16, 4001, 10578, 4182, 27
https://tests.stockfishchess.org/tests/view/68b886778f94a4e5a7fe77d9

closes https://github.com/official-stockfish/Stockfish/pull/6289

Bench: 2493363
 2025-09-06 07:55:14 +02:00
Shawn XuandJoost VandeVondele adfddd2c98 Add scaling note to STC/LTC tunes 
It has been repeatedly shown that such tunes are suspectible to become
anti-scaling. Below are some recent examples:

https://github.com/official-stockfish/Stockfish/commit/2e91a8635468e40c89a2303ce50384864d088611
https://github.com/official-stockfish/Stockfish/commit/d11f49b790429c236a1a4169f0d8052635fc03dc

Passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 32448 W: 8651 L: 8342 D: 15455
Ptnml(0-2): 81, 3695, 8408, 3914, 126
https://tests.stockfishchess.org/tests/view/6899489b0049e8ccef9d64ad

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 73854 W: 19042 L: 18649 D: 36163
Ptnml(0-2): 37, 7908, 20659, 8271, 52
https://tests.stockfishchess.org/tests/view/689abbe7fd8719b088c8d514

Revert VVLTC with STC bound:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 53802 W: 14030 L: 13740 D: 26032
Ptnml(0-2): 5, 4924, 16754, 5212, 6
https://tests.stockfishchess.org/tests/view/68a9a9f575da51a345a5a675

Revert VVLTC with LTC bound:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 53658 W: 14022 L: 13699 D: 25937
Ptnml(0-2): 3, 4894, 16712, 5217, 3
https://tests.stockfishchess.org/tests/view/68a8d2b2b6fb3300203bca77

https://tests.stockfishchess.org/tests/view/688cf38bf17748b4d23c8057
https://tests.stockfishchess.org/tests/view/6890bc7792fcad741b804a19

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 74928 W: 19466 L: 19071 D: 36391
Ptnml(0-2): 37, 8048, 20901, 8439, 39

Failed Non-regression VLTC:
LLR: -2.94 (-2.94,2.94) <-1.75,0.25>
Total: 57704 W: 14643 L: 14928 D: 28133
Ptnml(0-2): 5, 5925, 17280, 5634, 8
https://tests.stockfishchess.org/tests/view/6890bc7792fcad741b804a19

(Note that an STC-tuned version passed non-regression, but was shortly
simplified)

https://github.com/official-stockfish/Stockfish/pull/6040

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 27776 W: 7352 L: 7054 D: 13370
Ptnml(0-2): 68, 3126, 7221, 3386, 87
https://tests.stockfishchess.org/tests/view/680ec0f83629b02d74b1605b

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 161304 W: 41432 L: 40864 D: 79008
Ptnml(0-2): 61, 17305, 45357, 17863, 66
https://tests.stockfishchess.org/tests/view/680ec7f93629b02d74b16084

Failed Non-regression VVLTC:
LLR: -2.94 (-2.94,2.94) <-1.75,0.25>
Total: 313466 W: 80573 L: 81089 D: 151804
Ptnml(0-2): 38, 29689, 97782, 29199, 25
https://tests.stockfishchess.org/tests/view/6810d0533629b02d74b16756

https://github.com/official-stockfish/Stockfish/pull/5907
https://github.com/official-stockfish/Stockfish/pull/5887

Passed LTC with STC bounds:
https://tests.stockfishchess.org/tests/view/67b115dd6c6b9e172ad1592f
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 75756 W: 19393 L: 19044 D: 37319
Ptnml(0-2): 60, 8251, 20913, 8588, 66

Passed LTC with LTC bounds:
https://tests.stockfishchess.org/tests/view/67af5f5d6c6b9e172ad15765
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 108126 W: 27880 L: 27412 D: 52834
Ptnml(0-2): 85, 11786, 29866, 12228, 98

Revert VVLTC w/ STC bounds:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 56342 W: 14536 L: 14246 D: 27560
Ptnml(0-2): 7, 5061, 17741, 5359, 3
https://tests.stockfishchess.org/tests/view/67be4f8ad8d5c2c657c52d10

Revert VVLTC w/ LTC bounds:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 66562 W: 17364 L: 17016 D: 32182
Ptnml(0-2): 3, 6145, 20637, 6493, 3
https://tests.stockfishchess.org/tests/view/67bcd25ff6b602bd7222ea40

closes https://github.com/official-stockfish/Stockfish/pull/6284

no functional change
 2025-09-02 20:42:03 +02:00
Shawn XuandJoost VandeVondele f2da0ccf3f Simplify SMP Reduction 
Passed Non-regression SMP STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 232784 W: 59845 L: 59841 D: 113098
Ptnml(0-2): 289, 26459, 62934, 26379, 331
https://tests.stockfishchess.org/tests/view/68ab96bf75da51a345a5acd6

Passed Non-regression SMP LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 374270 W: 95978 L: 96113 D: 182179
Ptnml(0-2): 118, 38575, 109888, 38432, 122
https://tests.stockfishchess.org/tests/view/68abcf1c75da51a345a5adb6

closes https://github.com/official-stockfish/Stockfish/pull/6285

Bench: 2667107
 2025-09-02 20:41:08 +02:00
Shawn XuandJoost VandeVondele 75ac6c7a06 simplify stalemate further 
Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 155200 W: 40650 L: 40562 D: 73988
Ptnml(0-2): 533, 17588, 41258, 17700, 521
https://tests.stockfishchess.org/tests/view/68abe11375da51a345a5adec

Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 82824 W: 21442 L: 21287 D: 40095
Ptnml(0-2): 51, 8738, 23675, 8901, 47
https://tests.stockfishchess.org/tests/view/68b205606217b8721dca9c8e

10k Stalemate:
Elo: 1.46 ± 1.2 (95%) LOS: 99.0%
Total: 10000 W: 4640 L: 4598 D: 762
Ptnml(0-2): 0, 140, 4678, 182, 0
https://tests.stockfishchess.org/tests/view/68b2059b6217b8721dca9c90

closes https://github.com/official-stockfish/Stockfish/pull/6283

Bench: 2431727
 2025-09-02 20:39:02 +02:00
Daniel MonroeandJoost VandeVondele da63060ea3 Simplify sign term in quiet histories 
Simplify sign term in quiet histories

Passed simplification STC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 497824 W: 129130 L: 129418 D: 239276
Ptnml(0-2): 1546, 59040, 128008, 58792, 1526
https://tests.stockfishchess.org/tests/view/68a2a9c1b6fb3300203bc3ed

Passed simplification LTC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 70830 W: 18185 L: 18016 D: 34629
Ptnml(0-2): 36, 7658, 19861, 7821, 39
https://tests.stockfishchess.org/tests/view/68af36c96217b8721dca98d9

closes https://github.com/official-stockfish/Stockfish/pull/6282

Bench: 2393762
 2025-09-02 20:37:04 +02:00
Joost VandeVondeleandxu-shawn 3833583862 limit dynamic reduction. 
fixes https://github.com/official-stockfish/Stockfish/issues/6280

prevents probcut from extending depth as analyzed here:
https://github.com/official-stockfish/Stockfish/pull/6254#issuecomment-3239144280

passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 86688 W: 22591 L: 22426 D: 41671
Ptnml(0-2): 305, 10125, 22311, 10306, 297
https://tests.stockfishchess.org/tests/view/68b418ab467ff96994ae4cd5

passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 82914 W: 21287 L: 21130 D: 40497
Ptnml(0-2): 39, 8959, 23305, 9114, 40
https://tests.stockfishchess.org/tests/view/68b47ffa78ed7a752a9e8f36

closes https://github.com/official-stockfish/Stockfish/pull/6286

Bench: 2787731

Co-Authored-By: xu-shawn <50402888+xu-shawn@users.noreply.github.com>
 2025-09-02 20:34:47 +02:00
Arseniy SurkovandJoost VandeVondele 731ad9bbc3 Simplify adjust_key50 template 
Remove the AfterMove template from the adjust_key50 function, which is only ever called with false.

closes https://github.com/official-stockfish/Stockfish/pull/6278

No functional change
 2025-08-30 15:17:57 +02:00
Sebastian BuchwaldandJoost VandeVondele 7a3483fa9e Remove superfluous cast 
closes https://github.com/official-stockfish/Stockfish/pull/6277

No functional change
 2025-08-30 15:14:51 +02:00
Torsten HellwigandJoost VandeVondele 6a6dadb5a6 Remove buggy and unused function 
The function does not fulfill its purpose and is not used anywhere.
See https://discord.com/channels/435943710472011776/1101022188313772083/1409801409855094874

closes https://github.com/official-stockfish/Stockfish/pull/6275

no functional change
 2025-08-30 15:13:40 +02:00
Shawn XuandJoost VandeVondele 3f18352396 Further Simplify Stalemate Detection 
Passed Non-regression STC:
LLR: 2.98 (-2.94,2.94) <-1.75,0.25>
Total: 191520 W: 49633 L: 49582 D: 92305
Ptnml(0-2): 557, 20676, 53260, 20693, 574
https://tests.stockfishchess.org/tests/view/68ab570075da51a345a5abe1

Passed Non-regression LTC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 212934 W: 54643 L: 54618 D: 103673
Ptnml(0-2): 117, 22417, 61364, 22462, 107
https://tests.stockfishchess.org/tests/view/68ab84e975da51a345a5ac6b

10k Stalemate:
Elo: 0.35 ± 1.2 (95%) LOS: 71.6%
Total: 10000 W: 4602 L: 4592 D: 806
Ptnml(0-2): 0, 148, 4694, 158, 0
nElo: 1.99 ± 6.8 (95%) PairsRatio: 1.07
https://tests.stockfishchess.org/tests/view/68abeb8175da51a345a5af82

closes https://github.com/official-stockfish/Stockfish/pull/6268

Bench: 2420973
 2025-08-30 15:12:06 +02:00
Shawn XuJoost VandeVondeleDaniel Monroe
 		7d213afd37 Non-functional simplifications 
closes https://github.com/official-stockfish/Stockfish/pull/6267

No functional change

Co-authored-by: Daniel Monroe <github.com@danielmonroe.net>
 2025-08-30 15:09:47 +02:00
Shawn XuandJoost VandeVondele a289ee389a Simplify Capture Futility Pruning 
Passed Non-regression STC:
LLR: 2.97 (-2.94,2.94) <-1.75,0.25>
Total: 187904 W: 48639 L: 48583 D: 90682
Ptnml(0-2): 560, 22150, 48502, 22154, 586
https://tests.stockfishchess.org/tests/view/68aad56075da51a345a5a9e3

Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 94302 W: 24246 L: 24101 D: 45955
Ptnml(0-2): 44, 10274, 26371, 10417, 45
https://tests.stockfishchess.org/tests/view/68ab541975da51a345a5aacf

closes https://github.com/official-stockfish/Stockfish/pull/6266

Bench: 2376717
 2025-08-30 15:09:00 +02:00
Robert Nurnberg @ elitebookandJoost VandeVondele 222df615c1 revert #6259 
The recent commit af181d9 was merged as a simplification, but unfortunately hurts mate finding efficiency.

https://github.com/vondele/matetrack/blob/69f5c5e8627c163a6a8480b869ee09bc44dc44d4/matetrack1000000.csv#L4075-L4076

So this PR proposes to revert it, while adding a comment in the code for future reference.

closes https://github.com/official-stockfish/Stockfish/pull/6269

Bench: 2566711
 2025-08-30 15:06:57 +02:00