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 5.4.0/mingw 5.3.1 on Ubuntu 16.04.
2.Jan.2016: BMI build now slightly faster due to profiling.
Development builds for macOS are available at stockfishchess.de
Read the FAQ or leave a comment.

goto Gull
!! latest version !!


Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Wed Feb 21 22:31:38 2018 +0100
Timestamp: 1519248698

Move pawn_attacks_bb() helper to bitboard.h

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Mike Whiteley
Date: Wed Feb 21 21:47:04 2018 +0100
Timestamp: 1519246024

rename shift variables.

Where variable names are explicitly incorrect, I feel morally obligated to at least
suggest an alternative. There are many, but these two are especially egregious.

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Alain SAVARD
Date: Wed Feb 21 00:52:59 2018 +0100
Timestamp: 1519170779

Avoid a compilation warning

Avoid a warning while compiling with gcc version 4.9.2

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Marco Costalba
Date: Tue Feb 20 17:11:18 2018 +0100
Timestamp: 1519143078

Code style in evaluate.cpp

Passed STC
LLR: 2.95 (-2.94,2.94) [-4.00,0.00]
Total: 75666 W: 16482 L: 16616 D: 42568
http://tests.stockfishchess.org/tests/view/5a8953af0ebc590297cc83ab

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Sun Feb 18 01:51:35 2018 +0100
Timestamp: 1518915095

Update list of authors after Stockfish 9

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Mike Whiteley
Date: Thu Feb 15 19:38:09 2018 +0100
Timestamp: 1518719889

Simplify trapped rook

As far as can tell, semiopenFiles are set if there is a pawn anywhere on
the file. The removed condition would be true even if the pawns were very
advanced, which doesn't make sense if we're looking for a trapped rook.
Seems the engine fairs better with this removed. My guess s that the
condition that mobility is 3 or less does this well enough.

Begs the question whether this is a mobility issue alone... not sure.
Should I do LTC test?

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 13377 W: 3009 L: 2871 D: 7497
http://tests.stockfishchess.org/tests/view/5a855be40ebc590297cc8166

Passed LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 16288 W: 2813 L: 2685 D: 10790
http://tests.stockfishchess.org/tests/view/5a8575a80ebc590297cc817e

Bench: 5006365
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Ronald de Man
Date: Mon Feb 12 23:14:33 2018 +0100
Timestamp: 1518473673

Fix gcc PGO build on Windows

This fixes the issue #1375 of the PGO builds failing under Windows:
https://github.com/official-stockfish/Stockfish/issues/1375

Solution found during this discussion in the fishcooking forum:
https://groups.google.com/forum/?fromgroups=#!topic/fishcooking/RjIPgeFFLPQ

Closes #1408.

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Marco Costalba
Date: Mon Feb 12 22:58:25 2018 +0100
Timestamp: 1518472705

Code style fixes in search.cpp

Some code style triviality.

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Marco Costalba
Date: Mon Feb 12 22:42:39 2018 +0100
Timestamp: 1518471759

Update travis CI to g++7

Use newer g++ 7 instead of 6 in travis CI tests.

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stefano Cardanobile
Date: Fri Feb 9 19:07:19 2018 +0100
Timestamp: 1518199639

Introduce dynamic contempt

Make contempt dependent on the current score of the root position.

The idea is that we now use a linear formula like the following to decide
on the contempt to use during a search :

contempt = x + y * eval

where x is the base contempt set by the user in the "Contempt" UCI option,
and y * eval is the dynamic part which adapts itself to the estimation of
the evaluation of the root position returned by the search. In this patch,
we use x = 18 centipawns by default, and the y * eval correction can go
from -20 centipawns if the root eval is less than -2.0 pawns, up to +20
centipawns when the root eval is more than 2.0 pawns.

To summarize, the new contempt goes from -0.02 to 0.38 pawns, depending if
Stockfish is losing or winning, with an average value of 0.18 pawns by default.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 110052 W: 24614 L: 23938 D: 61500
http://tests.stockfishchess.org/tests/view/5a72e6020ebc590f2c86ea20

LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 16470 W: 2896 L: 2705 D: 10869
http://tests.stockfishchess.org/tests/view/5a76c5b90ebc5902971a9830

A second match at LTC was organised against the current master:

ELO: 1.45 +-2.9 (95%) LOS: 84.0%
Total: 19369 W: 3350 L: 3269 D: 12750
http://tests.stockfishchess.org/tests/view/5a7acf980ebc5902971a9a2e

Finally, we checked that there is no apparent problem with multithreading,
despite the fact that some threads might have a slightly different contempt
level that the main thread.

Match of this version against master, both using 5 threads, time control 30+0.3:
ELO: 2.18 +-3.2 (95%) LOS: 90.8%
Total: 14840 W: 2502 L: 2409 D: 9929
http://tests.stockfishchess.org/tests/view/5a7bf3e80ebc5902971a9aa2

Include suggestions from Marco Costalba, Aram Tumanian, Ronald de Man, etc.

Bench: 5207156
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Leonid Pechenik
Date: Fri Feb 9 10:41:32 2018 +0100
Timestamp: 1518169292

Retire "Extra thinking before accepting draw PVs"

This patch simplifies the time management code, removing the extra
thinking time for moves with draw PV and increasing thinking time
for all moves proportionally by around 4%.

Last time when the time management was carefully tuned was 1.5-2 years
ago. As new patches were getting added, time management was drifting out
of optimum. This happens because when search becomes more precise pv and
score are becoming more stable, there are less fail lows, best move is
picked earlier and there are less best move changes. All this factors are
entering in time management, and average time per move is decreasing with
more and more good patches. For individual patches such effect is small
(except some) and may be up or down, but when there are many of them,
effect is more substantial. The same way benchmark with more and more
patches is slowly drifting down on average.

So my understanding that back in October adding more think time for draw
PV showed positive Elo because time management was not well tuned, there
was more time available, and think_hard patch applied this additional time
to moves with draw PV, while just retuning back to optimum would recover Elo
anyway. It is possible that absence of contempt also helped, as SF9 is showing
less 0.0 scores than the October version.

Anyway, to me it seems that proper place to deal with draw PV is search, and
contempt sounds as much better solution. In time management there is little
additional elo, and if some code is not helping like removed here, it is better
to discard it. It is simpler to find genuine improvement if code is clean.

• Passed STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 20487 W: 4558 L: 4434 D: 11495
http://tests.stockfishchess.org/tests/view/5a7706ec0ebc5902971a9854

• Passed LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 41960 W: 7145 L: 7058 D: 27757
http://tests.stockfishchess.org/tests/view/5a778c830ebc5902971a9895

• Passed an additional non-regression [-5..0] test at the time control
of 60sec for the game (sudden death) with disabled draw adjudication:
LLR: 2.95 (-2.94,2.94) [-5.00,0.00]
Total: 8438 W: 1675 L: 1586 D: 5177
http://tests.stockfishchess.org/tests/view/5a7c3d8d0ebc5902971a9ac0

• Passed an additional non-regression [-5..0] test at the time control
of 1sec+1sec per move with disabled draw adjudication:
LLR: 2.97 (-2.94,2.94) [-5.00,0.00]
Total: 27664 W: 5575 L: 5574 D: 16515
http://tests.stockfishchess.org/tests/view/5a7c3e820ebc5902971a9ac3

This is a functional change for the time management code.

Bench: 4983414
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Fri Feb 9 01:12:08 2018 +0100
Timestamp: 1518135128

Fix bug for 'eval' command in terminal

The 'eval' debugging command in Terminal did not initialize the Eval::Contempt
variable, leading to random output during debugging sessions (normal search
was unaffected by the bug).

Example of session where the two 'eval' commands should give the same output,
but did not:

./stockfish
position startpos
d
eval
go depth 20
d
eval

The bug is fixed by initializing Eval::Contempt to SCORE_ZERO in Eval::trace

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: FauziAkram
Date: Thu Feb 8 15:14:02 2018 +0100
Timestamp: 1518099242

A combo of 3 successful tuning patches

Shelter Weakness by Fauzi Akram Dabat
Threats by Alain Savard
Passed Pawns by Alain Savard

STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 51378 W: 11592 L: 11223 D: 28563
http://tests.stockfishchess.org/tests/view/5a79e2fe0ebc5902971a99d1

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 21631 W: 3888 L: 3661 D: 14082
http://tests.stockfishchess.org/tests/view/5a7aefe80ebc5902971a9a39

Bench: 4983414
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: protonspring
Date: Thu Feb 8 10:46:27 2018 +0100
Timestamp: 1518083187

Obey skipQuiets strictly in MovePicker

The current logic in master is to continue return quiet moves if their
history score is above 0. It appears as though this check can be
removed, which is also more logically consistent with the “skipQuiets”
semantics used in search.cpp.

This patch may open new opportunitiesto get Elo by changing or
tuning the definition of 'moveCountPruning' in line 830 of search.cpp,
because obeying skipQuiets without checking the history scores makes
the search more sensitive to 'moveCountPruning'.

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 34780 W: 7680 L: 7584 D: 19516
http://tests.stockfishchess.org/tests/view/5a79f8d80ebc5902971a99db

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 38757 W: 6732 L: 6641 D: 25384
http://tests.stockfishchess.org/tests/view/5a7afebe0ebc5902971a9a46

Bench 4954595
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Joost VandeVondele
Date: Wed Feb 7 01:29:53 2018 +0100
Timestamp: 1517963393

More robust bench extraction

Allow travis.yml to recognize a variety of bench formats in commit messages, for instance:

Bench: 5023593. (really).
bench: 5023593 (it was 1234567)
bench : 5023593 (blah blah)
Bench:5023593
Bench: 5023593. 567 something (1234567) 563

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: syzygy1
Date: Tue Feb 6 00:46:50 2018 +0100
Timestamp: 1517874410

Enable LTO for clang

Enable link-time optimization in the Makefile when compiling with clang.
Also update travis.yml to use clang++-5.0 and llvm-5.0-dev.

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: protonspring
Date: Mon Feb 5 17:27:59 2018 +0100
Timestamp: 1517848079

Don’t score and sort all captures in RECAPTURES stage.

For these recaptures, we’re are only considering those captures
that recapture the recapture square (small portion of all the
captures). Therefore, scoring all of the captures and pick_besting
out of the whole group is not necessary.

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 85583 W: 18978 L: 18983 D: 47622
http://tests.stockfishchess.org/tests/view/5a717faa0ebc590f2c86e9a7

LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 20231 W: 3533 L: 3411 D: 13287
http://tests.stockfishchess.org/tests/view/5a73ad330ebc5902971a96ba

Bench: 5023593
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Sun Feb 4 21:42:56 2018 +0100
Timestamp: 1517776976

Revert "Implement old 'multipv' search"

This revert the following commit:
https://github.com/official-stockfish/Stockfish/commit/44a7db0f9ac02d2461aff39e25f1ac9107ffbfac

Bug report by Ronald de Man in issue:
https://github.com/official-stockfish/Stockfish/issues/1392

Bench: 5023629
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: protonspring
Date: Sun Feb 4 14:57:57 2018 +0100
Timestamp: 1517752677

Simplify qsearch stages in MovePicker

The difference between QCAPTURES_1 and QCAPTURES_2 quiescence search stages
boils down to a simple check of depth. The way it's being done now is
unnecessarily complex.

This patch is simpler, clearer, and easier to understand.

Passed SPRT[-3..1] test at STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 99755 W: 22158 L: 22192 D: 55405
http://tests.stockfishchess.org/tests/view/5a71f41c0ebc590f2c86e9cb

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: joergoster
Date: Sun Feb 4 13:35:44 2018 +0100
Timestamp: 1517747744

Implement 'old' multipv search.

It seems to be a waste of time to loop through all remaining root moves
after finishing each PV line. This patch skips this until we have reached
the last PV line (this is the way it was done in Glaurung and very early
versions of Stockfish).

No functional change in Single PV mode.

MultiPV=3 STC and LTC tests
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 3113 W: 1248 L: 1064 D: 801

LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 2260 W: 848 L: 679 D: 733

Bench: 5023629
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Sun Feb 4 02:08:09 2018 +0100
Timestamp: 1517706489

Restore development version

No functional change.
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Stéphane Nicolet
Date: Sun Feb 4 00:13:56 2018 +0100
Timestamp: 1517699636

Improved spelling, grammar and comment

Author: Ben Koshy

No functional change
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: mstembera
Date: Wed Jan 31 11:41:09 2018 +0100
Timestamp: 1517395269

Stockfish 9

Official release version of Stockfish 9

Bench 5023629
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Torsten Franz
Date: Tue Jan 30 09:40:56 2018 +0100
Timestamp: 1517301656

Retire lever (#1378)

Retire the lever bonus from pawns evaluation

STC: http://tests.stockfishchess.org/tests/view/5a6aef5c0ebc590d945d59c8
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 88290 W: 19549 L: 19560 D: 49181

LTC: http://tests.stockfishchess.org/tests/view/5a6b70140ebc590d945d59f7
LLR: 3.22 (-2.94,2.94) [-3.00,1.00]
Total: 104603 W: 18105 L: 18108 D: 68390

Bench 5023629
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Windows 32
Linux x64 for Haswell CPUs
Linux x64 for modern computers
Linux x64
Author: Rocky640
Date: Sun Jan 28 14:56:45 2018 +0100
Timestamp: 1517147805

Limit the king distance factor when evaluating passed pawns (#1373)

Limit the king distance factor when evaluating passed pawns
Passed STC
http://tests.stockfishchess.org/tests/view/5a6bf7290ebc590d945d5a3a
LLR: 3.31 (-2.94,2.94) [0.00,5.00]
Total: 23987 W: 5550 L: 5281 D: 13156

and LTC
http://tests.stockfishchess.org/tests/view/5a6c57710ebc590297c36af2
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 16926 W: 3014 L: 2820 D: 11092

Bench: 5059457

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