Similar to PSQT we only need one instance of the Endgames resource. The current per thread copies are identical and read only(after initialization) so from a design point of view it doesn't make sense to have them.
Tested for no slowdown.
http://tests.stockfishchess.org/tests/view/5c94377a0ebc5925cfff43ca
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 17320 W: 3487 L: 3359 D: 10474
No functional change.
Adding a clamp function makes some of these range limitations a bit prettier and removes some #include's.
STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 28117 W: 6300 L: 6191 D: 15626
http://tests.stockfishchess.org/tests/view/5c9aa1df0ebc5925cfff8fcc
Non functional change.
This is covered by the line just before. If we would like to protect
against the piece value of e.g. a N == B, this could be done by an
assert, no need to do this at runtime.
No functional change.
Preparation commit for the upcoming Stockfish 10 version, giving a chance to catch last minute feature bugs and evaluation regression during the one-week code freeze period. Also changing the copyright dates to include 2019.
No functional change
This patch introduces a non-linear bonus for pawns, along with some
(linear) corrections for the other pieces types.
The original values were obtained by a massive non-linear tuning of both
pawns and other pieces by GuardianRM, while Alain Savard and Chris Cain
later simplified the patch by observing that, apart from the pawn case, the
tuned corrections were in fact almost affine and could be incorporated in
our current code base via the piece values in types.h (offset) and the diagonal
of the quadratic matrix (slope). See discussion in PR#1725 :
https://github.com/official-stockfish/Stockfish/pull/1725
STC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 42948 W: 9662 L: 9317 D: 23969
http://tests.stockfishchess.org/tests/view/5b6ff6e60ebc5902bdba1d87
LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 19683 W: 3409 L: 3206 D: 13068
http://tests.stockfishchess.org/tests/view/5b702dbd0ebc5902bdba216b
How to continue from there?
- Maybe the non-linearity for the pawn value could be somewhat tempered
again and a simpler linear correction for pawns would work?
Closes https://github.com/official-stockfish/Stockfish/pull/1734
Bench: 4681496
This is a further step in the long quest for a simple way of determining
scale factors for the endgame.
Here we remove the artificial restriction in evaluate_scale_factor()
based on endgame score. Also SCALE_FACTOR_ONEPAWN can be simplified
away. The latter is a small non functional simplification with respect
to the version that was testedin the framework, verified on bench with
depth 22 for good measure.
Passed STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 49438 W: 9999 L: 9930 D: 29509
http://tests.stockfishchess.org/tests/view/5ae20c8b0ebc5963175205c8
Passed LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 101445 W: 15113 L: 15110 D: 71222
http://tests.stockfishchess.org/tests/view/5ae2a0560ebc5902a1998986
How to continue from there?
Maybe the general case could be scaled with pawns from both colors
without losing Elo. If that is the case, then this could be merged
somehow with the scaling in evaluate_initiative(), which also uses
a additive malus down when the number of pawns in the position goes
down.
Closes https://github.com/official-stockfish/Stockfish/pull/1570
Bench: 5254862
To more clearly distinguish them from "const" local variables, this patch
defines compile-time local constants as constexpr. This is consistent with
the definition of PvNode as constexpr in search() and qsearch(). It also
makes the code more robust, since the compiler will now check that those
constants are indeed compile-time constants.
We can go even one step further and define all the evaluation and search
compile-time constants as constexpr.
In generate_castling() I replaced "K" with "step", since K was incorrectly
capitalised (in the Chess960 case).
In timeman.cpp I had to make the non-local constants MaxRatio and StealRatio
constepxr, since otherwise gcc would complain when calculating TMaxRatio and
TStealRatio. (Strangely, I did not have to make Is64Bit constexpr even though
it is used in ucioption.cpp in the calculation of constexpr MaxHashMB.)
I have renamed PieceCount to pieceCount in material.h, since the values of
the array are not compile-time constants.
Some compile-time constants in tbprobe.cpp were overlooked. Sides and MaxFile
are not compile-time constants, so were renamed to sides and maxFile.
Non-functional change.
Implements renaming suggestions by Marco Costalba, Günther Demetz,
Gontran Lemaire, Ronald de Man, Stéphane Nicolet, Alain Savard,
Joost VandeVondele, Jerry Donald Watson, Mike Whiteley, xoto10,
and I hope that I haven't forgotten anybody.
Perpetual renaming thread for suggestions:
https://github.com/official-stockfish/Stockfish/issues/1426
No functional change.
For some reason, although game phase is used
only in material, it is computed in Position.
Move computation to material, where it belongs,
and remove the useless call chain.
No functional change.
Addition of correction values in case of Imbalance of queens,
depending on the number of light pieces on the side without a queen.
Passed patch:
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 29036 W: 5379 L: 5130 D: 18527
LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 13680 W: 1836 L: 1674 D: 10170
Bench: 6258930
Closes#1155
Instead of having a continuous increasing bonus for our number of pawns when calculating imbalance, use a separate lookup array with tuned values.
Idea by GuardianRM.
STC
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16155 W: 2980 L: 2787 D: 10388
LTC
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 100478 W: 13055 L: 12615 D: 74808
Bench: 6128779
Closes#1030
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#464
Coverity scan warns about uninitialized 'sf' argument when
calling probe(). Actually it is a false positive because
argument is passed by reference and assigned inside
probe(). Nevertheless it is a hint that fucntion signature
is a bit tricky, so rewrite it in a more conventional way,
assigning 'sf' from probe() return value.
No functional change.
Import C++11 branch from:
https://github.com/mcostalba/Stockfish/tree/c++11
The version imported is teh last one as of today:
6670e93e50
Branch is fully equivalent with master but syzygy
tablebases that are missing (but will be added with
next commit).
bench: 8080602
It is up to material (and pawn) table look up
code to know where the per-thread tables are,
so change API to reflect this.
Also some comment fixing while there
No functional change.
Move all in evaluation.
Simplify the code and concentrate in a single place
all the logic behind space evaluation, making it much
more clear.
Verified also at STC it does not regress due to a possible
slow down:
LLR: 3.91 (-2.94,2.94) [-3.00,1.00]
Total: 65744 W: 13285 L: 13194 D: 39265
No functional change.
Currently king has no material key associated because
it can never happen to find a legal position without
both kings, so there is no need to keep track of it.
The consequence is that a position with only the two
kings has material key set at zero and if the material
hash table is empty any entry will match and this is
wrong.
Normally bug is hidden becuase the checking for a draw
with pos.is_draw() is done earlier than evaluate() call,
so that we never check in gameplay the material key of a
position with two kings.
Nevertheless the bug is there and can be reproduced setting
at startup a position with only two kings and typing
'eval' from prompt.
The fix is very simple: add a random key also for the king.
Also fixed the condition in material.cpp to avoid asserting
when a 'just 2 kings' postion is evaluated.
No functional change.
Retire KmmKm evaluation function. Instead give a very drawish
scale factor when the material advantage is small and not much
material remains.
Retire NoPawnsSF array. Pawnless endgames without a bishop will
now be scored higher. Pawnless endgames with a bishop pair will
be scored lower. The effect of this is hopefully small.
Consistent results both at short TC (fixed games):
ELO: -0.00 +-2.1 (95%) LOS: 50.0%
Total: 40000 W: 7405 L: 7405 D: 25190
And long TC (fixed games):
ELO: 0.77 +-1.9 (95%) LOS: 78.7%
Total: 39690 W: 6179 L: 6091 D: 27420
bench: 7213723
