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

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!! 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: ajithcj
Date: Sun Jul 24 09:54:07 2016 +0200
Timestamp: 1469346847

Allow null pruning at depth 1

This removes a check that prevents null pruning at depth 1 PLY.

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 23445 W: 4638 L: 4521 D: 14286

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 61416 W: 8627 L: 8563 D: 44226

bench: 8145304
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: Stefano80
Date: Sun Jul 24 08:55:58 2016 +0200
Timestamp: 1469343358

See prune at higher depth

Allow SEE pruning at higher depths in shallow depth
pruning using a threshold increasing with depth.

STC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 35366 W: 7011 L: 6724 D: 21631

LTC
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 15578 W: 2243 L: 2070 D: 11265

Bench: 8417887
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: ajithcj
Date: Sat Jul 16 07:35:31 2016 +0200
Timestamp: 1468647331

Gradually relax the NMP staticEval check

Gradually relax the NMP staticEval check as we go to
higher depths.

Use tuned values.

STC
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16745 W: 3371 L: 3168 D: 10206

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 5906 W: 875 L: 736 D: 4295

bench: 8548212
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: Lyudmil Antonov
Date: Sat Jul 16 07:06:13 2016 +0200
Timestamp: 1468645573

Workaround gcc stack alignment bug

GCC uses SSE instructions to move data but in 32-bit gcc version used
by abrok the stack is not 16-byte aligned due to a bug.

This patch workaround teh bug by not using the stack
to store KingFlank[]

Fixes issue #721.

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: Tue Jul 12 08:47:21 2016 +0200
Timestamp: 1468306041

Fix extract_ponder_from_tt()

Checking for legality of a possible ponder move
must be done before we undo the first pv move,
of course. (spotted by mohammed li.)

This obviously only has any effect when playing in ponder mode.

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: Fri Jul 8 09:35:22 2016 +0200
Timestamp: 1467963322

King tropism

Bonus for each square that we attack in the flank where the opponent
king is. Squares that we attack twice and are not protected by an enemy
pawn count double.

Passed STC:
http://tests.stockfishchess.org/tests/view/577dfca60ebc5972faa166b8
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 48373 W: 9832 L: 9481 D: 29060

And LTC:
http://tests.stockfishchess.org/tests/view/577e77870ebc5972faa166df
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 8881 W: 1408 L: 1255 D: 6218

Bench: 7577046
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: Thu Jul 7 08:39:58 2016 +0200
Timestamp: 1467873598

More safe checks

Consider a check given by a rook or a minor to be a "safe check"
also in the case where supported by another piece,
and given on a square only defended by a queen

Was yellow STC
http://tests.stockfishchess.org/tests/view/576fcbc80ebc5972faa163e8
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 55453 W: 10431 L: 10315 D: 34707

Passed LTC
http://tests.stockfishchess.org/tests/view/57733a0b0ebc5972faa164b7
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 54550 W: 7671 L: 7365 D: 39514

bench: 7398346
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: ajithcj
Date: Sat Jul 2 16:43:49 2016 +0200
Timestamp: 1467470629

Use staticEval in null prune condition

Don't null prune at depth < 12 if staticEval < beta

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 62858 W: 12035 L: 11632 D: 39191

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 49784 W: 7009 L: 6720 D: 36055

bench: 8054611
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: loco-loco
Date: Sun Jun 26 10:25:05 2016 +0200
Timestamp: 1466929505

Removing inCheck condition for counter move bonus

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 20206 W: 3946 L: 3823 D:

LTC:
LLR: 3.10 (-2.94,2.94) [-3.00,1.00]
Total: 25004 W: 3512 L: 3390 D: 18102

Bench: 8172428
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: Sat Jun 25 11:46:17 2016 +0200
Timestamp: 1466847977

Restore standard passed pawn definition

Use the usual and accepted passed pawn semantic
instead of a non-standard one and remove a FIXME.

STC (http://tests.stockfishchess.org/tests/view/576401350ebc5972faa1608d):
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 29646 W: 5663 L: 5557 D: 18426

LTC (http://tests.stockfishchess.org/tests/view/5764e4e90ebc5972faa160c3):
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 40224 W: 5578 L: 5484 D: 29162

bench: 7543902
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: ElbertoOne
Date: Fri Jun 24 08:46:36 2016 +0200
Timestamp: 1466750796

Remove redundant PvNode condition

After commit 6d58bf777caa323 we always call PvNodes
with cutNode set to false.

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: VoyagerOne
Date: Fri Jun 24 08:26:39 2016 +0200
Timestamp: 1466749599

Comment out a redundant condition

Take advantage that VALUE_NONE = 32002 to remove
the condition.

Commented out and not removed becuase it is tricky
to rely on the hidden value of VALUE_NONE and code
can break in case we change VALUE_NONE in the future.

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: Jonathan Calovski
Date: Tue Jun 21 09:01:39 2016 +0200
Timestamp: 1466492499

Remove scalefactor dependency

STC
http://tests.stockfishchess.org/tests/view/5764539e0ebc5972faa160a4
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 43878 W: 8289 L: 8208 D: 27381

LTC
http://tests.stockfishchess.org/tests/view/5764f0130ebc5972faa160c9
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39338 W: 5408 L: 5313 D: 28617

bench: 7977279
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: ElbertoOne
Date: Sun Jun 19 18:04:22 2016 +0200
Timestamp: 1466352262

On IID do not always search with cutNode = true

On IID now search with cutNode value instead of fixed value true.

STC (http://tests.stockfishchess.org/tests/view/575fa3860ebc5972faa15f67):
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 163974 W: 30744 L: 30874 D: 102356

LTC (http://tests.stockfishchess.org/tests/view/5763b0640ebc5972faa16075):
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 48363 W: 6611 L: 6528 D: 35224

Bench: 7806393
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: VoyagerOne
Date: Sat Jun 18 08:32:25 2016 +0200
Timestamp: 1466231545

Simplify Check Extension

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 32704 W: 6146 L: 6045 D: 20513

LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 146622 W: 19967 L: 20017 D: 106638

Bench: 8245662
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: ajithcj
Date: Wed Jun 15 08:55:40 2016 +0200
Timestamp: 1465973740

Don't insert pv back into tt

This code was added before the accurate pv patch, when
we retrieved PV directly from TT.

It's not required for correct (and long) PVs any more and
should be safe to remove it.

Also, allowing helper threads to repeatedly over-write
TT doesn't seem to make sense(that was probably an un-intended
side-effect of lazy smp). Before Lazy SMP only Main Thread used
to run ID loop and insert PV into TT.

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 74346 W: 13946 L: 13918 D: 46482

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 47265 W: 6531 L: 6447 D: 34287

bench: 8819179
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: lucasart
Date: Wed Jun 15 08:47:08 2016 +0200
Timestamp: 1465973228

Do not hardcode Debug Log File

Allow to specifiy the log file name, this comes
handy in case of self-matches so that each SF
instance writes into a different log file.

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: Sat Jun 11 09:24:40 2016 +0200
Timestamp: 1465629880

Filter root moves filter before copy to threads

Currently root moves are copied to all teh threads
but are DTZ filtered only in main thread at the
beginning of teh search.

This patch moves the TB filtering before the
copy of root moves fixing issue #679

https://github.com/official-stockfish/Stockfish/issues/679

No bench 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: VoyagerOne
Date: Fri Jun 10 07:27:47 2016 +0200
Timestamp: 1465536467

Stat Formula Tweak

bonus = d * d + 2 * d - 2

STC:
LLR: 2.94 (-2.94,2.94) [0.00,4.00]
Total: 99444 W: 18274 L: 17778 D: 63392

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 89757 W: 12285 L: 11896 D: 65576

bench: 8276130
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: VoyagerOne
Date: Fri Jun 10 07:15:56 2016 +0200
Timestamp: 1465535756

Tweak check extension condition

There are two concepts with this patch:

Limit check extensions by using move count.
The idea is to limit search explosion.

Always extend check if the first move gives check.
The idea is to save expensive SEE calls, since the vast
majority of first move will have SEE value >= 0, also
first move may still be strong even if the SEE is negative.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16503 W: 3068 L: 2873 D: 10562

LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 37202 W: 5261 L: 5014 D: 26927

bench: 8543366
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: Fri Jun 10 06:53:07 2016 +0200
Timestamp: 1465534387

Small Queen simplification

Moving a few lines from evaluate_threats to evaluate_pieces allows to
a) Remove a condition pos.count<QUEEN>(Them) == 1
b) use precalculated s instead of pos.square(Them)
c) do not check the condition at all in queenless endings

Passed STC
http://tests.stockfishchess.org/tests/view/5752e0410ebc59029919b1f4
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 67175 W: 12194 L: 12152 D: 42829

and LTC
http://tests.stockfishchess.org/tests/view/57587b140ebc59029919b2f4
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 20276 W: 2774 L: 2653 D: 14849

bench: 7907962
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: Fri Jun 10 06:43:37 2016 +0200
Timestamp: 1465533817

Avoid some redundant scaling function calls

Posted by Mohammed Li here:
https://groups.google.com/forum/?fromgroups=#!topic/fishcooking/N-PHfN0O79o

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: ElbertoOne
Date: Tue Jun 7 15:15:49 2016 +0200
Timestamp: 1465305349

LMR reduction parameter tweak

More reduction for cut nodes, less for moves that escape a capture:

STC (http://tests.stockfishchess.org/tests/view/57548c1e0ebc59029919b247):
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 60165 W: 11519 L: 11149 D: 37497

LTC (http://tests.stockfishchess.org/tests/view/57555b570ebc59029919b260):
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 10353 W: 1493 L: 1317 D: 7543

Bench: 8902859
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 Jun 7 15:06:26 2016 +0200
Timestamp: 1465304786

Fix syzygy DTZ bug

In this position: 3K4/8/3k4/8/4p3/4B3/5P2/8 w - - 0 5

Current DTZ probe returns 1 instead of 15

What happens is that the double push f4 is erroneously detected as a win move.

After the push we have:

[D]3K4/8/3k4/8/4pP2/4B3/8/8 b - f3 0 5

And here the code misses the possible ep capture exf3.

The bug is in probe_dtz_no_ep() where is used probe_ab() that is
blind to ep captures so it returns v == 2 (win) for position

3K4/8/3k4/8/4pP2/4B3/8/8 b - f3 0 5

Note that at the caller site the original position did not have any
possible ep capture, so probe_dtz() returns immediately after calling
probe_dtz_no_ep().

The fix is to call the ep-aware probe_wdl() instead of probe_ab()

I have verified that DTZ is correct now and also there are no more
mistmatches compared to the new 'syzygy' branch. Tested on a set of
more than 600 endgame positions, included some tricky ones.

For people interested to redo the test or doing additional tests
please pull branch tb_dbg from https://github.com/mcostalba/Stockfish repo.

bench: 8450534 (bench unaffected because syzygy is not exercized during bench)
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: VoyagerOne
Date: Fri Jun 3 19:58:42 2016 +0200
Timestamp: 1464976722

Simplify Futility Pruning

Don't update bestValue when futility pruning.

STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 21933 W: 4031 L: 3912 D: 13990

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 46225 W: 6115 L: 6028 D: 34082

Bench: 8450534

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