Commit 8cb543f
Careful SMP locking - Fix very occasional hangs
Louis Zulli reported that Stockfish suffers from very occasional hangs with his 20 cores machine.
Careful SMP debugging revealed that this was caused by "a ghost split point slave", where thread
was marked as a split point slave, but wasn't actually working on it.
The only logical explanation for this was double booking, where due to SMP race, the same thread
is booked for two different split points simultaneously.
Due to very intermittent nature of the problem, we can't say exactly how this happens.
The current handling of Thread specific variables is risky though. Volatile variables are in some
cases changed without spinlock being hold. In this case standard doesn't give us any kind of
guarantees about how the updated values are propagated to other threads.
We resolve the situation by enforcing very strict locking rules:
- Values for key thread variables (splitPointsSize, activeSplitPoint, searching)
can only be changed when the thread specific spinlock is held.
- Structural changes for splitPoints[] are only allowed when the thread specific spinlock is held.
- Thread booking decisions (per split point) can only be done when the thread specific spinlock is held.
With these changes hangs didn't occur anymore during 2 days torture testing on Zulli's machine.
We probably have a slight performance penalty in SMP mode due to more locking.
STC (7 threads):
ELO: -1.00 +-2.2 (95%) LOS: 18.4%
Total: 30000 W: 4538 L: 4624 D: 20838
However stability is worth more than 1-2 ELO points in this case.
No functional change
Resolves official-stockfish#422
Scales the endgame score by the number of pawns.
Credits goes also to Stephane Nicolet for his great idea of scaling by pawns.
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 9994 W: 1929 L: 1760 D: 6305
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 11240 W: 1789 L: 1626 D: 7825
bench 7298564
Resolves official-stockfish#423
Remove unnecessary generation check in TT save
Checking for generation is unnecessary because if the key matches then the entry was probed and refreshed earlier.
STC 2MB
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 57391 W: 10671 L: 10613 D: 36107
http://tests.stockfishchess.org/tests/view/55ef59fa0ebc5976a2d6da5d
LTC 8MB
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 60732 W: 9260 L: 9199 D: 42273
http://tests.stockfishchess.org/tests/view/55ef8fe60ebc5976a2d6da6b
STC 16MB
LLR: 2.95 (-2.94,2.94) [-4.00,0.00]
Total: 23443 W: 4369 L: 4293 D: 14781
http://tests.stockfishchess.org/tests/view/55ef8fe60ebc5976a2d6da6b
No functional change
Resolves official-stockfish#427
Reduce writes in TT::probe().
Only refresh TT entry when it's really necessary.
This should give a small speed boost for some machines.
And it's a risk-free change.
No functional change.
Resolves official-stockfish#429
Refine ranks and increase resulting bonus.
STC:
LLR: 2.94 (-2.94,2.94) [0.00,4.00]
Total: 272379 W: 51773 L: 50658 D: 169948
LTC:
LLR: 3.06 (-2.94,2.94) [0.00,4.00]
Total: 41504 W: 6555 L: 6273 D: 28676
bench: 7658406
Resolves official-stockfish#430
Simplify outposts
This outpost simplification removes a number of unnecessary if statements. No functional change, but maybe I want to test it anyway.
Fix build errors
revert
Rework lock protecting
When changing 'search' and 'splitPointsSize' we have to
use thread locks, not split point ones, because can_join()
is called under the formers.
Verified succesfully with 24 hours toruture tests with 20
cores machine by Louis Zulli: it does not hangs.
Verifyed for no regressions with STC, 7 threads:
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 52804 W: 8159 L: 8087 D: 36558
No functional change.
Bonus for checking moves
STC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 14531 W: 2765 L: 2576 D: 9190
LTC:
LLR: 3.20 (-2.94,2.94) [0.00,5.00]
Total: 52518 W: 8107 L: 7782 D: 36629
Bench: 7556477
Resolves official-stockfish#435
File based passed pawn bonus
Add file based bonus for passed pawns. Values tuned by SPSA.
STC:
LLR: 3.33 (-2.94,2.94) [0.00,5.00]
Total: 36889 W: 6805 L: 6507 D: 23577
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 32301 W: 5101 L: 4858 D: 22342
Bench: 8073614
Resolves official-stockfish#436
Run PVS-STUDIO analyzer
Fix issues after a run of PVS-STUDIO analyzer.
Mainly false positives but warnings are anyhow
useful to point out not very readable code.
Noteworthy is the memset() one, where PVS prefers ss-2
instead of stack. This is because memeset() could
be optimized away by the compiler when using 'stack',
due to stack being a local variable no more used after
memset. This should normally not happen, but when
it happens it leads to very sublte and difficult
to find bug, so better to be safe than sorry.
No functional change.
Fix a comment in TTEntry::save
Comment was slightly incorrect.
No functional change.
Add Trevis CI support
Add Travis CI support to GitHub repo.
After every push to master, Travis will build
the sources directly from GitHub repo according
to .travis.yml and verify everything is ok.
No functional change.
Remove queen threat evaluation
Threats by queen seem to be worthless.
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 13627 W: 2607 L: 2473 D: 8547
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 19146 W: 2950 L: 2827 D: 13369
Bench: 8222484
Resolves official-stockfish#439
Tuning of assorted values
Passed STC
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 45401 W: 8590 L: 8274 D: 28537
Passed LTC
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 36089 W: 5589 L: 5331 D: 25169
Bench: 8397672
Resolves official-stockfish#445
Travis CI: add clang and osx
Extend builds to clang and osx platforms.
And check bench numbers.
No functional change.
Travis CI: add gcc 4.8 for osx
This setup was still missing.
Suggested by Stéphane Nicolet.
No functional change.
Retire rook contact checks
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 34114 W: 6363 L: 6265 D: 21486
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 61776 W: 9349 L: 9289 D: 43138
LTC (after rebasing):
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 15261 W: 2343 L: 2214 D: 10704
Bench: 7523382
Resolves official-stockfish#442
Combination of two ideas:
Apply bonus for the prior CMH that caused a fail low.
Balance Stats: CMH and History bonuses are updated differently.
This eliminates the "fudge" factor weight when scoring moves. Also
eliminated discontinuity in the gravity history stat formula. (i.e. stat
scores will no longer inverse when depth exceeds 22)
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 21802 W: 4107 L: 3887 D: 13808
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 46036 W: 7046 L: 6756 D: 32234
Bench: 7677367
Asymmetry bonus for the attacking side
Use asymmetry in the position (king separation, pawn structure) to
compute an "initiative bonus" for the attacking side.
Passed STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 14563 W: 2826 L: 2636 D: 9101
And LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 14363 W: 2317 L: 2141 D: 9905
Bench: 8116244
Resolves official-stockfish#462
Lazy SMP
Start all threads searching on root position and
use only the shared TT table as synching scheme.
It seems this scheme scales better than YBWC for
high number of threads.
Verified for nor regression at STC 3 threads
LLR: -2.95 (-2.94,2.94) [-3.00,1.00]
Total: 40232 W: 6908 L: 7130 D: 26194
Verified for nor regression at LTC 3 threads
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 28186 W: 3908 L: 3798 D: 20480
Verified for nor regression at STC 7 threads
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 3607 W: 674 L: 526 D: 2407
Verified for nor regression at LTC 7 threads
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 4235 W: 671 L: 528 D: 3036
Tested with fixed games at LTC with 20 threads
ELO: 44.75 +-7.6 (95%) LOS: 100.0%
Total: 2069 W: 407 L: 142 D: 1520
Tested with fixed games at XLTC (120secs) with 20 threads
ELO: 28.01 +-6.7 (95%) LOS: 100.0%
Total: 2275 W: 349 L: 166 D: 1760
Original patch of mbootsector, with additional work
from Ivan Ivec (log formula), Joerg Oster (id loop
simplification) and Marco Costalba (assorted formatting
and rework).
Bench: 8116244
Almost passed tuning attempts
Collect and give a second try to some almost passed tuning attempts and
one-line tweaks from the last month.
Passed STC
LLR: 3.07 (-2.94,2.94) [0.00,4.00]
Total: 15124 W: 2974 L: 2756 D: 9394
And LTC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 21577 W: 3507 L: 3289 D: 14781
Bench: 8855226
Resolves official-stockfish#464
Update authors
Fishtest is a key factor of SF success.
Thanks to Fishtest we have not only greately
improved ELO but, even more important, we
have enabled a kind of joint development and
testing that it is the herat of on open
source project like SF.
Open sourcing is not just about open code, it is
about commuity development. In case of a chess engine
this has never been possible before due to missing
a strong and strict testing environment that allows
many people to contribute in a safe and coordinate way.
Fishtest is a new way of developing chess engines,
something that has never exsisted before.
No functional change.
History pruning
Prune moves with negative History
and CMH scores at low depth.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 24182 W: 4672 L: 4439 D: 15071
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 12579 W: 1959 L: 1792 D: 8828
bench: 8907701
Simplify threats
Using less parameters and code to compute Threats
Includes also a few spacing edits.
Run as a simplification.
Passed STC 10+0.1
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 18879 W: 3725 L: 3600 D: 11554
Passed LTC 60+0.4
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 74116 W: 11001 L: 10958 D: 52157
bench: 8004751
Cleanup history stats
And other assorted trivia.
No functional change.
KRPPKRP endgame: Simplify ugly switch statement
No functional change
Resolves official-stockfish#470
Use atomics instead of volatile
Rely on well defined behaviour for message passing, instead of volatile. Three
versions have been tested, to make sure this wouldn't cause a slowdown on any
platform.
v1: Sequentially consistent atomics
No mesurable regression, despite the extra memory barriers on x86. Even with 15
threads and extreme time pressure, both acting as a magnifying glass:
threads=15, tc=2+0.02
ELO: 2.59 +-3.4 (95%) LOS: 93.3%
Total: 18132 W: 4113 L: 3978 D: 10041
threads=7, tc=2+0.02
ELO: -1.64 +-3.6 (95%) LOS: 18.8%
Total: 16914 W: 4053 L: 4133 D: 8728
v2: Acquire/Release semantics
This version generates no extra barriers for x86 (on the hot path). As expected,
no regression either, under the same conditions:
threads=15, tc=2+0.02
ELO: 2.85 +-3.3 (95%) LOS: 95.4%
Total: 19661 W: 4640 L: 4479 D: 10542
threads=7, tc=2+0.02
ELO: 0.23 +-3.5 (95%) LOS: 55.1%
Total: 18108 W: 4326 L: 4314 D: 9468
As suggested by Joona, another test at LTC:
threads=15, tc=20+0.05
ELO: 0.64 +-2.6 (95%) LOS: 68.3%
Total: 20000 W: 3053 L: 3016 D: 13931
v3: Final version: SeqCst/Relaxed
threads=15, tc=10+0.1
ELO: 0.87 +-3.9 (95%) LOS: 67.1%
Total: 9541 W: 1478 L: 1454 D: 6609
Resolves official-stockfish#474
Some code and comment cleanup
- Remove all references to split points
- Some grammar and spelling fixes
No Functional change
Resolves official-stockfish#478
Reduce variation in rootDepth between different threads
Reduce the variation in Root Depth between different threads. This
prevents threads from searching at a depth much higher than Main Thread.
Performed well at STC 24 Threads:
ELO: 3.44 +-3.8 (95%) LOS: 96.1%
Total: 10000 W: 1627 L: 1528 D: 6845
And LTC 24 Threads
LLR: 1.43 (-2.94,2.94) [0.00,4.00]
Total: 3804 W: 500 L: 420 D: 2884
ELO : +7.31
p-value: 73.16%
Passed no regression at STC 3 Threads:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 40457 W: 7148 L: 7060 D: 26249
And LTC 3 Threads:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 17704 W: 2489 L: 2364 D: 12851
Raising a pull request early as 24 Thread tests are very expensive and
this is clearly a positive gain at high thread counts and high time
controls. The change is a small parameter tweak with no additional
logic.
No functional change for single thread mode.
Resolves official-stockfish#481
New History Bonus Formula
bonus = d^2 + d - 1
Bench: 8639247
Resolves official-stockfish#484
Assorted trivia in search.cpp
The only interesting change is the moving of
stack[MAX_PLY+4] back to its original position
in id_loop (now renamed Thread::search).
No functional change.
Pick bestmove from the deepest thread.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 26930 W: 4441 L: 4214 D: 18275
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 7783 W: 1017 L: 876 D: 5890
No functional change in single thread mode
Resolves official-stockfish#485
Get rid of timer thread
Unfortunately std::condition_variable::wait_for()
is not accurate in general case and the timer thread
can wake up also after tens or even hundreds of
millisecs after time has elapsded. CPU load, process
priorities, number of concurrent threads, even from
other processes, will have effect upon it.
Even official documentation says: "This function may
block for longer than timeout_duration due to scheduling
or resource contention delays."
So retire timer and use a polling scheme based on a
local thread counter that counts search() calls and
a small trick to keep polling frequency constant,
independently from the number of threads.
Tested for no regression at very fast TC 2+0.05 th 7:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 32969 W: 6720 L: 6620 D: 19629
TC 2+0.05 th 1:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 7765 W: 1917 L: 1765 D: 4083
And at STC TC, both single thread
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 15587 W: 3036 L: 2905 D: 9646
And with 7 threads
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 8149 W: 1367 L: 1227 D: 5555
bench: 8639247
Ensure that rootDepth < DEPTH_MAX
Indeed, if we use a depth >= DEPTH_MAX, we start having negative depth in the
TT (due to int8_t cast).
No functional change in single thread mode
Resolves official-stockfish#490
Avoid friend
operator<<(os, pos) does not need to access any private members of pos.
No functional change.
Resolves official-stockfish#492
Fix broken UCI 'wait for stop'
When we reach the maximum depth, we can finish the
search without a raise of Signals.stop. However, if
we are pondering or in an infinite search, the UCI
protocol states that we shouldn't print the best move
before the GUI sends a "stop" or "ponderhit" command.
It was broken by lazy smp. Fix it by moving the stopping
of the threads after waiting for GUI.
No functional change.
Retire ThreadBase
Now that we don't have anymore TimerThread, there is
no need of this long class hierarchy.
Also assorted reformatting while there.
To verify no regression, passed at STC with 7 threads:
LLR: 2.97 (-2.94,2.94) [-5.00,0.00]
Total: 30990 W: 4945 L: 4942 D: 21103
No functional change.
Bonus for reachable outpost
Give a bonus for outpost squares which in reach of a bishop or knight.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 22725 W: 4570 L: 4339 D: 13816
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 15019 W: 2333 L: 2157 D: 10529
Bench: 8503181
Resolves official-stockfish#495
Do not conceal the invocation of the benchmark program
It is better to be able to see what arguments it is being called with.
No functional change
Resolves official-stockfish#497
History Pruning: Don't prune the main killer move.
Also increased pruned depth to 4.
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 23380 W: 4581 L: 4350 D: 14449
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 28934 W: 4329 L: 4105 D: 20500
Bench: 8369743
Resolves official-stockfish#498
Rewrite how threads are spawned
Instead of creating a running std::thread and
returning, wait in Thread c'tor that the native
thread of execution goes to sleep in idle_loop().
In this way we can simplify how search is started,
because when main thread is idle we are sure also
all other threads will be idle, in any case, even
at thread creation and startup.
After lazy smp went in, we can simpify and rewrite
a lot of logic that is now no more needed. This is
hopefully the final big cleanup.
Tested for no regression at 5+0.1 with 3 threads:
LLR: 2.95 (-2.94,2.94) [-5.00,0.00]
Total: 17411 W: 3248 L: 3198 D: 10965
No functional change.
Fix TT comment and static_assert()
Comment is based on a misunderstanding of what unaligned memory access is. Here
is an article that explains it very clearly:
https://www.kernel.org/doc/Documentation/unaligned-memory-access.txt
No matter how we define TTEntry or TTCluster, there will never be any unaligned
memory access. This is because the complier knows the alignment rules, and does
the necessary adjustments to make sure unaligned memory access does not occur.
The issue being adressed here has nothing to do with unaligned memory access. It
is about cache performance. In order to achieve best cache performance:
- we prefetch the cacheline as soon as possible.
- we ensure that TT clusters do not spread across two cachelines. If they did,
we would need to prefetch 2 cachelines, which could hurt cache performance.
Therefore the true conditions to achieve this are:
1/ start adress of TT is cache line aligned. void TranspositionTable::resize()
enforces this.
2/ TT cluster size should *divide* the cache line size. Currently, we pack 2
clusters per cache lines. It used to be 1 before "TT sardines". Does not matter
what the ratio is, all we want is to fit an integer number of clusters per cache
line.
No functional change.
Resolves official-stockfish#506
Clean up RootMove less operator
This is used by std::stable_sort() to sort moves from highest score to lowest score.
1) The comment is incorrect since highest to lowest means descending.
2) It's more natural to implement a less operator using another less operator rather than a greater operator.
No functional change.
Resolves official-stockfish#504
Allow cross compilation of Windows binaries on a Linux system
that are PGO, LTO, and statically linked.
Credit: pasquale....@gmail.com
No functional change
Resolves official-stockfish#505
Revert "Allow cross compilation of Windows binaries on a Linux system"
This reverts commit 388630a.
Confuses fishtest build system
Introduce new Threats weights = {350, 256}
Raise the midgame threats weight by 37%.
Passed STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 8165 W: 1675 L: 1487 D: 5003
and LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 28181 W: 4141 L: 3912 D: 20128
Bench: 7824961
Resolves official-stockfish#512
Proper Makefile for cross compiling 64 or 32 bit PGO + LTO + static Windows binaries under Linux.
No functional change
Resolves official-stockfish#511
Simplify outpost code
Also inline defintions of SpaceMask and CenterBindMask.
Verified from assembly that compiler computes the values
at compile time, so it is also theoretical faster.
While there factor out scale factor evaluation.
No functional change.
New Tuned Weights
More accurate evaluation weights
Performed better at STC
LLR: 1.32 (-2.94,2.94) [0.00,4.00]
Total: 190043 W: 37433 L: 36675 D: 115935
Passed LTC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 30157 W: 4540 L: 4303 D: 21314
Bench: 9264977
Resolves official-stockfish#515
Fix MultiPv and Skill in SMP.
7 threads, 5+0.1:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 55460 W: 9665 L: 9601 D: 36194
No functional change in normal playing mode
Simplify time management and fix 'ponder on' bug
Simplify time management code by removing hard stops for unchanging first root moves.
Search is now stopped earlier at the end iteration if it did not have fail-lows at root.
This simplification also fixes pondering bug. Ponder flag was true by default
and cutechess-cli doesn't change it to false even though no pondering is possible.
Fix the issue by setting the default value of 'Ponder' flag to false.
10+0.1:
ELO: 3.51 +-3.0 (95%) LOS: 99.0%
Total: 20000 W: 3898 L: 3696 D: 12406
40+0.4:
ELO: 1.39 +-2.7 (95%) LOS: 84.7%
Total: 20000 W: 3104 L: 3024 D: 13872
60+0.06:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 37231 W: 5333 L: 5236 D: 26662
Stopped run at 100+1:
LLR: 1.09 (-2.94,2.94) [-3.00,1.00]
Total: 37253 W: 4862 L: 4856 D: 27535
Resolves official-stockfish#523
Fixes official-stockfish#510
Threats retuned
STC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 45239 W: 8913 L: 8591 D: 27735
LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 21046 W: 3200 L: 2989 D: 14857
Bench: 8012530
Resolves official-stockfish#526
Fix easy move bug in SMP mode
Fix a bug where we could stop the search after only 10% of time used due to a matching easy move but later switch to a different move that was never pre-screened as easy due to SMP thread select.
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27227 W: 4910 L: 4800 D: 17517
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 40368 W: 5826 L: 5733 D: 28809
Resolves official-stockfish#521
Distinct iteration paths for Lazy SMP threads
STC 5+0.1, threads 7
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 6026 W: 1047 L: 901 D: 4078
LTC: 20+0.2, threads 7
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 19739 W: 2910 L: 2721 D: 14108
STC 5+0.1, threads 20
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 2493 W: 462 L: 331 D: 1700
LTC 30+0.3, threads 20
ELO: 8.86 +-3.7 (95%) LOS: 100.0%
Total: 8000 W: 1076 L: 872 D: 6052
Bench: 8012530
Resolves official-stockfish#525
Remove unused field SearchStack::ttMove
No functional change
Resolves official-stockfish#533
Remove killer move conditions from LMR
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 8459 W: 1619 L: 1477 D: 5363
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 32239 W: 4404 L: 4299 D: 23536
Bench: 7597031
Resolves official-stockfish#534
New mobility bonus
Tuned the global mobility factor for each piece, as well as some +- delta,
The master mobility factor was {266,334} and tuning gave
{267, 362} +S(-2,-2) for the Knight
{249, 328} +S( 0,-2) for the Bishop
{298, 353} +S(1,1) for the Rook
{265, 358} +S(2,-1) for the Queen
Passed STC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 49402 W: 9367 L: 9037 D: 30998
and LTC
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 26831 W: 3871 L: 3658 D: 19302
Bench: 8355485
Resolves official-stockfish#536
Remove another unnecessary Search::Stack field
No functional change
Resolves official-stockfish#535
Fix compiling of 32 bit binary on 64-bit Windows
Two versions of mingw-w64 (targeting Win64 and Win32)
can be installed on Windows too.
No functional change
Resolves official-stockfish#532
Revert "Fix compiling of 32 bit binary on 64-bit Windows"
This reverts commit 1e8836d
Broken compile on mingw under Windows:
Config:
debug: 'yes'
optimize: 'yes'
arch: 'i386'
bits: '32'
prefetch: 'yes'
bsfq: 'no'
popcnt: 'no'
sse: 'yes'
pext: 'no'
Flags:
CXX: i686-w64-mingw32-c++
CXXFLAGS: -Wall -Wcast-qual -fno-exceptions -fno-rtti -std=c++11 -Wextra -Wshadow -g -O3 -msse
LDFLAGS: -static
Testing config sanity. If this fails, try 'make help' ...
mingw32-make[1]: Leaving directory 'C:/stockfish/src'
c:/MinGw/bin/mingw32-make ARCH=x86-32 COMP=mingw all
mingw32-make[1]: Entering directory 'C:/stockfish/src'
sh: C:\Program: No such file or directory
i686-w64-mingw32-c++ -Wall -Wcast-qual -fno-exceptions -fno-rtti -std=c++11 -Wextra -Wshadow -g -O3 -msse -c -o benchmark.o benchmark.cpp
<builtin>: recipe for target 'benchmark.o' failed
process_begin: CreateProcess(NULL, i686-w64-mingw32-c++ -Wall -Wcast-qual -fno-exceptions -fno-rtti -std=c++11 -Wextra -Wshadow -g -O3 -msse -c -o benchmark.o benchmark.cpp, ...) failed.
make (e=2): Impossibile trovare il file specificato.
mingw32-make[1]: *** [benchmark.o] Error 2
mingw32-make[1]: Leaving directory 'C:/stockfish/src'
makefile:401: recipe for target 'build' failed
mingw32-make: *** [build] Error 2
No functional change.
Move some globals into main thread scope
Make it explicit that those variables are not globals, but
are used only by main thread. I think it is a sensible
clarification because easy move is already tricky enough
and current patch makes the involved actors explicit.
No functional change.
Resolves official-stockfish#537
Stockfish 7 Beta 1
Bench: 8355485
No functional change
Fix assert with very high score position
In case of a very high material score, we can
overflow VALUE_INFINITE.
This patch fixes an assert with:
position fen 7k/QQQQR3/2B5/4KN1Q/3QQ3/8/8/4R3 b - - 0 1
go depth 1
No functional change.
Resolves official-stockfish#546
Correct Pawn Trace Score + Code Clean up
No functional change
Resolves official-stockfish#542
Stockfish 7 Beta 2
Bench: 8355485
No functional change
Update Copyright year
No functional change.
Resolves official-stockfish#554
Update AUTHORS and copyright notice
No functional change
Resolves official-stockfish#555
Stockfish 7
Bench: 8355485
No functional change
Restore development version
Adjust time used for move based on previous score
Use less time if evaluation is not worse than for previous move and even less time if in addition no fail low encountered for current iteration.
STC: 10+0.1
ELO: 5.37 +-2.9 (95%) LOS: 100.0%
Total: 20000 W: 3832 L: 3523 D: 12645
STC: 10+0.1
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 17527 W: 3334 L: 3132 D: 11061
LTC: 60+0.6
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 28233 W: 3939 L: 3725 D: 20569
LTC: 60+0.6
ELO: 2.43 +-1.4 (95%) LOS: 100.0%
Total: 60000 W: 8266 L: 7847 D: 43887
LTC: 60+0.06
LLR: 2.95 (-2.94,2.94) [-1.00,3.00]
Total: 38932 W: 5408 L: 5207 D: 28317
Resolves official-stockfish#547
Fine tuning of unsupported pawn penalty
Adjust the unsupported pawn penalty when the pawn is supporting 2 pawns
(for example g7 in f6-g7-h6)
Passed STC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 23833 W: 4384 L: 4158 D: 15291
Passed LTC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 42711 W: 5918 L: 5655 D: 31138
Bench: 8390233
Resolves official-stockfish#549
Retire CenterBind
And compensate in the PSQT.
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27714 W: 5161 L: 5052 D: 17501
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 36354 W: 5008 L: 4909 D: 26437
Bench: 8603285
Resolves official-stockfish#556
Tune time management for LTC
60+0.6:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 102533 W: 14270 L: 13842 D: 74421
Resolves official-stockfish#558
Update comments in LMR step
No functional change
Resolves official-stockfish#564
Adjust reductions based on history and cmh tables
STC:
LLR: 4.06 (-2.94,2.94) [0.00,5.00]
Total: 149395 W: 28029 L: 27208 D: 94158
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 9628 W: 1368 L: 1217 D: 7043
bench: 8076724
Resolves official-stockfish#565
Assorted English grammar changes
No functional change
Resolves official-stockfish#567
Rewrite time formula
Time management is really too complex, our aim is
to simplify it, but for time being at least rewrite
in an understandable way.
No functional change.
Makefile: Allow specifying compiler executable
No functional change
Resolves official-stockfish#570
Remove redundant -std=c++0x flag
This flag is functionally identical to '-std=c++11' flag which
is part of standard flags.
No functional change
Resolves official-stockfish#571
Depth margin parameter-tweak in TT-save
Verified that is improvement with multiple threads:
LLR: 2.95 (-2.94,2.94) [0.00,4.00] sprt @ 30+0.3 th 3
Total: 14817 W: 2103 L: 1915 D: 10799
LLR: 2.96 (-2.94,2.94) [0.00,4.00] sprt @ 15+0.15 th 7
Total: 10264 W: 1498 L: 1321 D: 7445
Verified that is not a significant regression with a single thread:
LLR: 2.96 (-2.94,2.94) [-4.00,0.00] sprt @ 60+0.6 th 1
Total: 23975 W: 3294 L: 3210 D: 17471
Resolves official-stockfish#575
Retire RootNode template
There is no reason to compile 3 different copies of search(). PV nodes are on
the cold path, and PvNode is a template parameter, so there is no cost in
computing:
const bool RootNode = PvNode && (ss-1)->ply == 0;
And this simplifies code a tiny bit as well.
Speed impact is negligible on my machine (i7-3770k, linux 4.2, gcc 5.2):
nps +/-
test 2378605 3118
master 2383128 2793
diff -4523 2746
Bench: 7751425
No functional change.
Resolves official-stockfish#568
Do not probe syzygy bases when castling is possible
Almost no functional change. Bench is unchanged.
Resolves official-stockfish#230
Resolves official-stockfish#573
rotating symmetric patterns with increasing skipsize
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00] sprt @ 5+0.1 th 21
Total: 7068 W: 1121 L: 975 D: 4972
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00] sprt @ 12+0.12 th 21
Total: 26691 W: 3594 L: 3481 D: 19616
No functional change with a single thread
Resolves official-stockfish#574
Time management simplification
10+0.1:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41963 W: 7967 L: 7883 D: 26113
60+0.6:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 132314 W: 17939 L: 17969 D: 96406
Resolves official-stockfish#580
Document HalfDensityMap
No functional change.
Resolves official-stockfish#584
Remove Weights
Removed remaining redundant weights for pawn structure,
passed pawns, space and king safety by redistributing them
into individual evaluation terms.
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 15173 W: 2790 L: 2659 D: 9724
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 43433 W: 5936 L: 5846 D: 31651
Bench: 7156237
Resolves official-stockfish#586
Fix futility pruning bug
PredictedDepth can be negative, causing the futility_margin to be negative.
It will be very difficult to tweak moveCount pruning and reduction formula, as they are tuned to prevent this behavior.
No functional change
Resolves official-stockfish#587
History Stat Formula Simplification
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 67476 W: 12561 L: 12521 D: 42394
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 111923 W: 15147 L: 15149 D: 81627
Bench: 8430465
Resolves official-stockfish#588
Remove slowMover
Removes a slowMover and one paramater from move_importance function.
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 77023 W: 14456 L: 14433 D: 48134
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 37175 W: 5190 L: 5092 D: 26893
Resolves official-stockfish#589
Revert "Remove slowMover"
This reverts commit 77fa960.
Resolves official-stockfish#590
Simplify Reduction Formula
Formula now only contains one coefficient. Making it much easier to tune.
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 187443 W: 34858 L: 35028 D: 117557
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 88329 W: 11982 L: 11953 D: 64394
Bench: 7521394
Resolves official-stockfish#591
Pass endgame value to evaluate_scale_factor()
No functional change
Resolves official-stockfish#592
Clean up depth reduction calculation
Might also be a slight speed up
No functional change
Resolves official-stockfish#593
Tweak initiative formula
Give more weight to the pawns number and
the vertical king distance in evaluate_initiative()
Passed STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 26729 W: 5067 L: 4825 D: 16837
and LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 60480 W: 8338 L: 8016 D: 44126
Bench: 8295162
Resolves official-stockfish#594
Passed pawn bonus simplification
STC: (yellow)
LLR: -2.96 (-2.94,2.94) [0.00,4.00]
Total: 86114 W: 16063 L: 15921 D: 54130
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 14347 W: 2025 L: 1896 D: 10426
Bench: 8576437
Resolves official-stockfish#595
Add followup moves history for move ordering
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 7955 W: 1538 L: 1378 D: 5039
LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 5323 W: 778 L: 642 D: 3903
Bench: 8261839
Resolves official-stockfish#599
Assorted cleanup of latest commits
No functional change.
Resolves official-stockfish#601
Simplify Safe Checks
STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 11796 W: 2211 L: 2074 D: 7511
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 14324 W: 1935 L: 1806 D: 10583
Bench: 8075202
Resolves official-stockfish#600
A small simplification in movepick.h
No functional change
Resolves official-stockfish#597
Simplify pawns King Safety calculation
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 130209 W: 23516 L: 23581 D: 83112
LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 33541 W: 4563 L: 4460 D: 24518
Bench: 8644370
Resolves official-stockfish#604
Raise endgame passed pawn and material values
STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 136149 W: 25213 L: 24588 D: 86348
LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 54637 W: 7533 L: 7238 D: 39866
Bench: 8546808
Resolves official-stockfish#608
Bonus for loose enemies
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 30504 W: 5743 L: 5485 D: 19276
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 11936 W: 1651 L: 1493 D: 8792
Bench: 8880041
Resolves official-stockfish#606
Rewrite bsfq management
Use compiler intrinsics when possible to
avoid writing platform specific asm code.
Tested on Windows 7 with MSVC 2013 and mingw 4.8.3 (32 and 64 bit)
and on Linux Mint with g++ 4.8.4 and clang 3.4 (32 and 64 bit).
No functional change
Resolves official-stockfish#609
Guard against UB in lsb/msb
lsb(b) and msb(b) are undefined when b == 0. This can lead to subtle bugs, where
the resulting code behaves differently on different configurations:
- It can be the home grown software LSB/MSB
- It can be the compiler generated software LSB/MSB (when using compiler
intrinsics without the right compiler flags to allow compiler to use hardware
LSB/MSB). Which of course depends on the compiler.
- It can be hardware LSB/MSB generated by the compiler.
- Not to mention that hardware LSB/MSB can return different value on different
hardware when b == 0.
No functional change
Resolves official-stockfish#610
A combo patch of two tuning patches
STC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 14223 W: 2700 L: 2494 D: 9029
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 66294 W: 9065 L: 8739 D: 48490
Bench: 7607385
Resolves official-stockfish#612
32-bit/64-bit Makefile fix
Counter intuitively, make build ARCH=x86-32 does NOT produce a 32-bit compile
when running a 64-bit OS. Nor would ARCH=x86-64 produce a 64-bit compile when
running a 32-bit OS (assuming it compiled w/o errors).
No functional change
Resolves official-stockfish#621
Simplify popcnt
Also a speedup(about 1%) on 64-bit w/o hardware popcnt
Retire Max15 and Full template parameters
(Contributed by Marco Costalba)
Now that we have just SW and HW versions, use
template default parameter to get rid of explicit
template parameters.
Retire bitcount.h and move the only defined
function to bitboard.h
No functional change
Resolves official-stockfish#620
Backward simplication
On top of the usual conditions
a) some opponent in front (but no lever)
b) some neighbours (in front) (but no neighbour behind or same rank)
c) < rank_5
to find out if a pawn is backward we look at the squares in front of this pawn to reach the same rank as the next neighbour.
In current master, a pawn is backward if any of those squares is controlled by an enemy pawn on an adjacent file
In this version, a pawn is ALSO backward if any of those squares is occupied by an enemy pawn.
STC:
http://tests.stockfishchess.org/tests/view/56fe7efd0ebc59301a3541f1
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 19051 W: 3557 L: 3433 D: 12061
LTC:
http://tests.stockfishchess.org/tests/view/56febc2d0ebc59301a354209
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 40810 W: 5619 L: 5526 D: 29665
Bench: 7525245
Resolves official-stockfish#614
Undefended King Ring
There was already a penalty for squares only defended by King (undefended)
This test records a penalty for completely undefended squares in the so called extended king-ring
(so if we exclude squares defended by a Kg8 for example, we only look at h6 g6 and f6)
We also exclude squares occupied by opponent pieces in this computation,
based on the following results
Was yellow at STC
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 112499 W: 20649 L: 20293 D: 71557
and passed LTC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 36805 W: 5100 L: 4857 D: 26848
Bench: 8430233
Resolves: official-stockfish#619
Small passed pawn simplification
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 21993 W: 4197 L: 4078 D: 13718
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 67213 W: 9135 L: 9077 D: 49001
Bench: 7482426
Resolves official-stockfish#622
Fix Travis Cl
Broken after "32-bit/64-bit Makefile fix" commit.
Ubuntu "Precise" 12.04.5 supports multilib only until
g++ 4.6 that is not enough to compile Stockfish.
So move to Ubuntu 14.04.4 LTS (Trusty Tahr)
No functional change.
Hide global visibility when not needed
Also move PieceValue definition in psqt.cpp,
where it is initialized.
Fix a warning in popcount16() with Intel compiler
No functional change.
Fix last search info carried over to mate position
When starting search in a mate or stalemate position, Stockfish does not
even care to reinitialize and start worker threads. However after search
all threads are checked for the best move.
This can lead to bestmove and info beeing carried over from the last
search.
Example session:
setoption name threads value 7
go movetime 4000
position startpos moves f2f3 e7e5 g2g4 d8h4
go movetime 4000
Actual output is like (almost always):
[...]
bestmove e2e4
info depth 0 score mate 0
info depth 20 seldepth 29 multipv 1 score cp 28 [...] pv e2e4
bestmove e2e4
Expected output / output after fix:
[...]
bestmove e2e4 ponder e7e6
info depth 0 score mate 0
bestmove (none)
Resolves official-stockfish#623
StateInfo is usually allocated on the stack by search()
And passed in do_move(), this ensures maximum efficiency and
speed and at the same time unlimited move numbers.
The draw back is that to handle Position init we need to
reserve a StateInfo inside Position itself and use at
init time and when copying from another Position.
After lazy SMP we don't need anymore this gimmick and we can
get rid of this special case and always pass an external
StateInfo to Position object.
Also rewritten and simplified Position constructors.
Verified it does not regress with a 3 threads SMP test:
ELO: -0.00 +-12.7 (95%) LOS: 50.0%
Total: 1000 W: 173 L: 173 D: 654
No functional change.
Add a second level of follow-up moves
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 6438 W: 1229 L: 1077 D: 4132
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 4000 W: 605 L: 473 D: 2922
bench: 7378965
Resolves official-stockfish#636
Fix incorrect draw detection
In this position we should have draw for repetition:
position fen rnbqkbnr/2pppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 moves g1f3 g8f6 f3g1
go infinite
But latest patch broke it.
Actually we had two(!) very subtle bugs, the first is that Position::set()
clears the passed state and in particular 'previous' member, so
that on passing setupStates, 'previous' pointer was reset.
Second bug is even more subtle: SetupStates was based on std::vector
as container, but when vector grows, std::vector copies all its contents
to a new location invalidating all references to its entries. Because
all StateInfo records are linked by 'previous' pointer, this made pointers
go stale upon adding more element to setupStates. So revert to use a
std::deque that ensures references are preserved when pushing back new
elements.
No functional change.
Remove some pointless micro-optimizations
Seems to give around 1% speed-up for CPUs with popcnt support.
Seems to give a very minor speed-up for CPUs without popcnt.
No functional change
Resolves official-stockfish#646
Use -O3 for all compilers (including ICC)
There seems to be no benefit from using -fast over -O3 with icc.
So use -O3 everywhere.
No functional change
Resolves official-stockfish#652
Use FMHs to assist with LMR formula.
STC:
LLR: 2.99 (-2.94,2.94) [0.00,5.00]
Total: 52232 W: 9654 L: 9304 D: 33274
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 115988 W: 15550 L: 15049 D: 85389
Bench: 7890808
Resolves official-stockfish#651
Isolated pawn simplification
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 117822 W: 21697 L: 21744 D: 74381
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 92307 W: 12330 L: 12305 D: 67672
Bench: 8813983
Resolves official-stockfish#659
Remove useless -mbmi flag in Makefile
I could not find anything documented that is necessary that prepending -mbmi to -mbmi2 gives some benefit.
Instead at
https://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html#x86-Built-in-Functions
The following built-in functions are available when -mbmi is used. All of them generate the machine instruction that is part of the name.
unsigned int __builtin_ia32_bextr_u32(unsigned int, unsigned int);
unsigned long long __builtin_ia32_bextr_u64 (unsigned long long, unsigned long long);
The following built-in functions are available when -mbmi2 is used. All of them generate the machine instruction that is part of the name.
unsigned int _bzhi_u32 (unsigned int, unsigned int)
unsigned int _pdep_u32 (unsigned int, unsigned int)
unsigned int _pext_u32 (unsigned int, unsigned int)
unsigned long long _bzhi_u64 (unsigned long long, unsigned long long)
unsigned long long _pdep_u64 (unsigned long long, unsigned long long)
unsigned long long _pext_u64 (unsigned long long, unsigned long long)
and at
https://gcc.gnu.org/ml/gcc/2014-02/msg00204.html
( "... The real optimization comes from being able to use pext
(parallel bit extract), which can implement several bextr expressions in
parallel.")
Apart from that we don't use all -msse -msse2 -msse3 -msse4.2 etc. but just -msse3 (or -msse4.2) only.
As regards to the speedup within noise level - this pull request is actually reversal of mcostalba#198 wherein prepending -mbmi to -mbmi2 was claimed to be 0.3% faster and here (removing -mbmi) gives 0.4% speed gain.
Use popcount intrinsic with Interl compiler
It seems that icc used our fallback version of popcount.
Now use intrinsics.
icc version 16.0.2 (gcc version 5.3.0 compatibility)
bmi2 compile
uname -r 4.5.1-1-ARCH
20xbench gives a nice speedup
./stockfish-icc-master 2161515 +- 34462
./stockfish-icc-sse42 2260857 +- 50349
Fix LazySMP when searching to a fixed depth.
Currently, helper threads will only search up to the
specified depth limit. Now let them search until the
main thread has finished the specified depth.
On the other hand, we don't want to pick a thread with
a higher search depth.
This may be considered cheating. ;-)
No functional change.
Fix a warning with MSVC
Introduced by 2dd24dc ("Use popcount intrinsic with Intel")
No functional change.
Simplify History LMR Formula
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41713 W: 7589 L: 7504 D: 26620
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 41353 W: 5484 L: 5391 D: 30478
Bench: 8946983
Retire __popcnt64 intrinsic
Just use _mm_popcnt_u64() that is available
both for MSVC abd Intel compiler.
Verified on MSVC that the produced assembly
has the hardware 'popcnt' instruction.
No functional change.
Unsafe checks
Introducing a new multi-purpose penalty related to King safety, which
includes all kind of potential checks (from unsafe or unavailable
squares currently occupied by some other piece)
This will indirectly detect and reward some pins, discovered checks, and
motifs such as square vacation, or rook behind its pawn and aligned with
King (example Black Rg8, g7 against Kg1),
and penalize some pawn blockers (if they move, it allows a discovered
check by the pawn).
And since it looks also at protected squares, it detects some potential
defense overloading.
Finally, the rook contact checks had been removed some time ago. This
test will give a small bonus for them, as well as for bishop contact
checks.
Passed STC
http://tests.stockfishchess.org/tests/view/5729ec740ebc59301a354b36
LLR: 2.94 (-2.94,2.94) [0.00,5.00]
Total: 13306 W: 2477 L: 2296 D: 8533
and LTC
http://tests.stockfishchess.org/tests/view/572a5be00ebc59301a354b65
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 20369 W: 2750 L: 2565 D: 15054
bench: 9298175
Merge good and bad quiets
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 58613 W: 10779 L: 10723 D: 37111
LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 33608 W: 4539 L: 4436 D: 24633
Bench: 9441294
Double pawn simplification
Try doubled pawn simplification, with psq
table compensation.
STC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 36094 W: 6558 L: 6463 D: 23073
LTC:
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 102352 W: 13417 L: 13404 D: 75531
Bench: 8716243
Fix a multiPV bug in lazy SMP
Where the helper threads were not doing multiPV at all.
Regression tested sprt @ 5+0.05 th 7
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 73918 W: 11891 L: 11853 D: 50174
bench: 8716243
Assorted pruning tweaks
LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 38257 W: 5206 L: 4961 D: 28090
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16550 W: 3110 L: 2914 D: 10526
Bench: 8428997
More detailed dependence of time allocation on the magnitude of score change
10+0.1:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 5657 W: 1130 L: 979 D: 3548
60+0.6:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 36884 W: 5002 L: 4762 D: 27120
bench: 8428997
Simplify doubled pawn
Only use doubled pawn malus when the doubled pawns are on consecutive squares.
Passed STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 7678 W: 1469 L: 1325 D: 4884
And LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 26739 W: 3562 L: 3449 D: 19728
Bench: 8211685
Teach check_blockers to check also non-king pieces
This is a prerequisite for next patch
No functional change.
Pins or discovered attacks on the opponent's queen
Bonus for pins or discovered attacks on the opponent's queen
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 32020 W: 5914 L: 5652 D: 20454
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 10946 W: 1530 L: 1375 D: 8041
Bench: 7031649
Tuned values for piece check and attack unit factors
A middle ground patch of two successful tuning patches,
one at STC, the other at LTC, which now passed both.
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 67893 W: 12777 L: 12384 D: 42732
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 30165 W: 4189 L: 3960 D: 22016
bench: 92095071 parent 3e2591d commit 8cb543f
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