In the spirit of previous such PRs, this PR proposes a collection of nonfunctional changes.
I am happy to incorporate changes from other devs, and revert some of the proposed changes if the maintainers ask me to.
Apart from trivial changes, the proposed changes so far include:
* A requested edit to `AUTHORS` and a resorting of all entries, following DIN 5007 for the treatment of any special characters.
* Exclude the two recent integer type renaming commits from git blame.
* Tightening of some static asserts in `history.h` to avoid overflows. (Note that rounding errors for floating point types could lead to the assert in `operator<<` triggering at run-time.)
* Re-instate the 0.5s maximal thinking time in case of a single legal move and reword the comment to make it clear that it should not be tuned.
* ~~A small refactoring of the network loading code thanks to @dubslow.~~
* A refactoring of the "dtz is dtm" code, also thanks to @dubslow.
closes https://github.com/official-stockfish/Stockfish/pull/6928
No functional change
After merging the HalfKA and Threats accumulators (7c7fe322) and the
subsequent removal of the double-incremental/fused update, a number of
NNUE helpers and fields became unreachable. Each was verified to have
zero callers/readers across the source tree:
- FusedUpdateData logic in FullThreats: the fused-update branch of
append_changed_indices and the FusedUpdateData parameter are unused;
the accumulator update no longer passes fused data.
- FullThreats::requires_refresh: never called. The live king-bucket
refresh check is HalfKAv2_hm::requires_refresh (PSQFeatureSet), used
in nnue_accumulator.
- HalfKAv2_hm::append_active_indices: never called. The live
active-index builder is FullThreats::append_active_indices
(ThreatFeatureSet).
- DirtyThreats::us, prevKsq and ksq: written in do_move but only read by
the now-removed FullThreats::requires_refresh. Removing them also
drops three stores from the do_move path.
- Unused feature Name constants and the unused FtOneVal / HiddenMaxVal
constants in nnue_common.h.
- Two stale feature-header banner comments.
closes https://github.com/official-stockfish/Stockfish/pull/6898
No functional change
example of using, to avoid mixed usage of std::uint/std::int and uint/int...
```cpp
using u64 = std::uint64_t;
using u32 = std::uint32_t;
using u16 = std::uint16_t;
using u8 = std::uint8_t;
using i64 = std::int64_t;
using i32 = std::int32_t;
using i16 = std::int16_t;
using i8 = std::int8_t;
using usize = std::size_t;
using isize = std::ptrdiff_t;
#if defined(__GNUC__) && defined(IS_64BIT)
__extension__ using u128 = unsigned __int128;
__extension__ using i128 = signed __int128;
#endif
```
closes https://github.com/official-stockfish/Stockfish/pull/6874
No functional change
Over the past few months our attacks and bitboard logic got a bit more involved and target specific, so I think it makes sense to split this up a bit more into separate files.
While it's not in an ideal state I think it's first step and can be improved later, `pawn_attacks_bb` could also be moved into the attacks.h but this was more of an oversight from my side.
closes https://github.com/official-stockfish/Stockfish/pull/6833
No functional change
Instead of checking whether a threat index is valid and then writing to
a vector if it isn't, we can instead always write to the buffer of the
vector, and only increase the size of the vector if the index is valid.
This saves some branch mispredictions.
passed STC:
https://tests.stockfishchess.org/tests/view/69ceb1689f7a7e3fdfc9a44b
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 205760 W: 53109 L: 52561 D: 100090
Ptnml(0-2): 603, 22552, 56076, 22992, 657
local speedtest shows
```
Result of 100 runs (cycles)
===========================
base (...ockfish.orig) = 296886 +/- 1645
test (...kfish.df0822) = 298862 +/- 1662
speedup % = +0.67 +/- 0.19
[95% CI; t-statistic]
p(speedup > 0) = 1.0000
p(speedup > .5%) = 0.9562
CPU: 16 x Intel(R) Core(TM) Ultra 9 185H
Hyperthreading: on
```
closes https://github.com/official-stockfish/Stockfish/pull/6703
No functional change
[STC](https://tests.stockfishchess.org/tests/live_elo/69cb991bc025c305b7daa219)
LLR: 2.97 (-2.94,2.94) <0.00,2.00>
Total: 47520 W: 12558 L: 12219 D: 22743
Ptnml(0-2): 190, 5474, 12102, 5795, 199
[LTC](https://tests.stockfishchess.org/tests/live_elo/69cc6b42731dfb72d2e92128)
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 123756 W: 31996 L: 31497 D: 60263
Ptnml(0-2): 81, 13512, 34221, 13955, 109
Adds features for pawns pushing against other pawns. For indexing, we
use the existing threats feature set by adding the forward square to the
squares threatened by a pawn. This threat is only enabled when another
pawn occupies that square. We then add appropriate logic changes in
`update_piece_threats` and `features/full_threats.cpp`.
The wonderful Ciekce (of Stormphrax) and peregrine (of Reckless) also
had similar ideas with adding forward pawn movements to TI, and I
appreciate their giving me motivation to figure out `nnue-pytorch` and
test it.
closes https://github.com/official-stockfish/Stockfish/pull/6694
Bench: 2926703
Passed STC (first run):
https://tests.stockfishchess.org/tests/view/698030ee6362aee5c8a552c7
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 120800 W: 31336 L: 30912 D: 58552
Ptnml(0-2): 330, 13084, 33172, 13460, 354
Passed LTC:
https://tests.stockfishchess.org/tests/view/6983946d473df9d1d24a916d
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 86850 W: 22352 L: 21951 D: 42547
Ptnml(0-2): 45, 8506, 25934, 8883, 57
Passed STC SMP (after changes made after opening the PR):
https://tests.stockfishchess.org/tests/view/6987b4c1b0f3ca5200aaf9da
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 84480 W: 21994 L: 21627 D: 40859
Ptnml(0-2): 98, 9378, 22932, 9723, 109
Passed STC (second run, as a sanity check made after changes made after opening the PR -- these changed, however, didn't change assembly code produced by the compiler):
https://tests.stockfishchess.org/tests/view/6987ad21b0f3ca5200aaf9c9
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 132192 W: 34526 L: 34083 D: 63583
Ptnml(0-2): 421, 14511, 35759, 15014, 391
GCC maps __builtin_prefetch locality=1 to PREFETCHT2 instruction, targeting L2
cache. To make things clear, added template-based approach as suggested by
Disservin.
PREFETCHT2 should be the appropriate choice for the 78 MB threat weight table:
avoids L1d pollution, parks data in L2 where it is promoted to L1d on actual
load.
With 200-500 cycle lead time from make_index, data has time to arrive in L2.
suggestions by Disservin and anematode included
closes https://github.com/official-stockfish/Stockfish/pull/6602
No functional change
[Passed STC](https://tests.stockfishchess.org/tests/live_elo/691fc321acb6dbdf23d07e4b):
```
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 215360 W: 55651 L: 55108 D: 104601
Ptnml(0-2): 520, 22399, 61290, 22960, 511
```
This PR is on top of ces42's work so I'll rebase if that PR changes.
Essentially, it comprises my adjustments to `make_index` that remained
unmerged before threat inputs was finalized.
The unsigned intermediate variables let us skip a bunch of useless sign
extensions (because Square and Piece inherit from `int8_t`, and C/C++
semantics require narrow integers to be promoted to `int` before doing
arithmetic on them). Additionally, by removing the special usage of
`offsets[][64]` and `[65]` the indexing becomes more efficient. (This
usage was a temporary hack from sscg anyway, so I think he'll like that
it's gone.) Finally, the `sf_assume` condition was fixed so that it
actually makes a difference to the compiler.
The speedup is fairly nice locally (combining both ces42's and these changes):
```
Result of 100 runs
==================
base (...kfish.master) = 1691982 +/- 1907
test (./stockfish ) = 1714349 +/- 1789
diff = +22367 +/- 2465
speedup = +0.0132
P(speedup > 0) = 1.0000
```
closes https://github.com/official-stockfish/Stockfish/pull/6445
No functional change
For each thread persist an accumulator cache for the network, where each
cache contains multiple entries for each of the possible king squares.
When the accumulator needs to be refreshed, the cached entry is used to more
efficiently update the accumulator, instead of rebuilding it from scratch.
This idea, was first described by Luecx (author of Koivisto) and
is commonly referred to as "Finny Tables".
When the accumulator needs to be refreshed, instead of filling it with
biases and adding every piece from scratch, we...
1. Take the `AccumulatorRefreshEntry` associated with the new king bucket
2. Calculate the features to activate and deactivate (from differences
between bitboards in the entry and bitboards of the actual position)
3. Apply the updates on the refresh entry
4. Copy the content of the refresh entry accumulator to the accumulator
we were refreshing
5. Copy the bitboards from the position to the refresh entry, to match
the newly updated accumulator
Results at STC:
https://tests.stockfishchess.org/tests/view/662301573fe04ce4cefc1386
(first version)
https://tests.stockfishchess.org/tests/view/6627fa063fe04ce4cefc6560
(final)
Non-Regression between first and final:
https://tests.stockfishchess.org/tests/view/662801e33fe04ce4cefc660a
STC SMP:
https://tests.stockfishchess.org/tests/view/662808133fe04ce4cefc667c
closes https://github.com/official-stockfish/Stockfish/pull/5183
No functional change
- remove the blank line between the declaration of the function and it's
comment, leads to better IDE support when hovering over a function to see it's
description
- remove the unnecessary duplication of the function name in the functions
description
- slightly refactored code for lsb, msb in bitboard.h There are still a few
things we can be improved later on, move the description of a function where
it was declared (instead of implemented) and add descriptions to functions
which are behind macros ifdefs
closes https://github.com/official-stockfish/Stockfish/pull/4840
No functional change
This introduces clang-format to enforce a consistent code style for Stockfish.
Having a documented and consistent style across the code will make contributing easier
for new developers, and will make larger changes to the codebase easier to make.
To facilitate formatting, this PR includes a Makefile target (`make format`) to format the code,
this requires clang-format (version 17 currently) to be installed locally.
Installing clang-format is straightforward on most OS and distros
(e.g. with https://apt.llvm.org/, brew install clang-format, etc), as this is part of quite commonly
used suite of tools and compilers (llvm / clang).
Additionally, a CI action is present that will verify if the code requires formatting,
and comment on the PR as needed. Initially, correct formatting is not required, it will be
done by maintainers as part of the merge or in later commits, but obviously this is encouraged.
fixes https://github.com/official-stockfish/Stockfish/issues/3608
closes https://github.com/official-stockfish/Stockfish/pull/4790
Co-Authored-By: Joost VandeVondele <Joost.VandeVondele@gmail.com>
Introduces a new NNUE network architecture and associated network parameters
The summary of the changes:
* Position for each perspective mirrored such that the king is on e..h files. Cuts the feature transformer size in half, while preserving enough knowledge to be good. See https://docs.google.com/document/d/1gTlrr02qSNKiXNZ_SuO4-RjK4MXBiFlLE6jvNqqMkAY/edit#heading=h.b40q4rb1w7on.
* The number of neurons after the feature transformer increased two-fold, to 1024x2. This is possibly mostly due to the now very optimized feature transformer update code.
* The number of neurons after the second layer is reduced from 16 to 8, to reduce the speed impact. This, perhaps surprisingly, doesn't harm the strength much. See https://docs.google.com/document/d/1gTlrr02qSNKiXNZ_SuO4-RjK4MXBiFlLE6jvNqqMkAY/edit#heading=h.6qkocr97fezq
The AffineTransform code did not work out-of-the box with the smaller number of neurons after the second layer, so some temporary changes have been made to add a special case for InputDimensions == 8. Also additional 0 padding is added to the output for some archs that cannot process inputs by <=8 (SSE2, NEON). VNNI uses an implementation that can keep all outputs in the registers while reducing the number of loads by 3 for each 16 inputs, thanks to the reduced number of output neurons. However GCC is particularily bad at optimization here (and perhaps why the current way the affine transform is done even passed sprt) (see https://docs.google.com/document/d/1gTlrr02qSNKiXNZ_SuO4-RjK4MXBiFlLE6jvNqqMkAY/edit# for details) and more work will be done on this in the following days. I expect the current VNNI implementation to be improved and extended to other architectures.
The network was trained with a slightly modified version of the pytorch trainer (https://github.com/glinscott/nnue-pytorch); the changes are in https://github.com/glinscott/nnue-pytorch/pull/143
The training utilized 2 datasets.
dataset A - https://drive.google.com/file/d/1VlhnHL8f-20AXhGkILujnNXHwy9T-MQw/view?usp=sharing
dataset B - as described in https://github.com/official-stockfish/Stockfish/commit/ba01f4b95448bcb324755f4dd2a632a57c6e67bc
The training process was as following:
train on dataset A for 350 epochs, take the best net in terms of elo at 20k nodes per move (it's fine to take anything from later stages of training).
convert the .ckpt to .pt
--resume-from-model from the .pt file, train on dataset B for <600 epochs, take the best net. Lambda=0.8, applied before the loss function.
The first training command:
python3 train.py \
../nnue-pytorch-training/data/large_gensfen_multipvdiff_100_d9.binpack \
../nnue-pytorch-training/data/large_gensfen_multipvdiff_100_d9.binpack \
--gpus "$3," \
--threads 1 \
--num-workers 1 \
--batch-size 16384 \
--progress_bar_refresh_rate 20 \
--smart-fen-skipping \
--random-fen-skipping 3 \
--features=HalfKAv2_hm^ \
--lambda=1.0 \
--max_epochs=600 \
--default_root_dir ../nnue-pytorch-training/experiment_$1/run_$2
The second training command:
python3 serialize.py \
--features=HalfKAv2_hm^ \
../nnue-pytorch-training/experiment_131/run_6/default/version_0/checkpoints/epoch-499.ckpt \
../nnue-pytorch-training/experiment_$1/base/base.pt
python3 train.py \
../nnue-pytorch-training/data/michael_commit_b94a65.binpack \
../nnue-pytorch-training/data/michael_commit_b94a65.binpack \
--gpus "$3," \
--threads 1 \
--num-workers 1 \
--batch-size 16384 \
--progress_bar_refresh_rate 20 \
--smart-fen-skipping \
--random-fen-skipping 3 \
--features=HalfKAv2_hm^ \
--lambda=0.8 \
--max_epochs=600 \
--resume-from-model ../nnue-pytorch-training/experiment_$1/base/base.pt \
--default_root_dir ../nnue-pytorch-training/experiment_$1/run_$2
STC: https://tests.stockfishchess.org/tests/view/611120b32a8a49ac5be798c4
LLR: 2.97 (-2.94,2.94) <-0.50,2.50>
Total: 22480 W: 2434 L: 2251 D: 17795
Ptnml(0-2): 101, 1736, 7410, 1865, 128
LTC: https://tests.stockfishchess.org/tests/view/611152b32a8a49ac5be798ea
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 9776 W: 442 L: 333 D: 9001
Ptnml(0-2): 5, 295, 4180, 402, 6
closes https://github.com/official-stockfish/Stockfish/pull/3646
bench: 5189338
A lot of optimizations happend since the NNUE was introduced
and since then some parts of the code were left unused. This
got to the point where asserts were have to be made just to
let people know that modifying something will not have any
effects or may even break everything due to the assumptions
being made. Removing these parts removes those inexisting
"false dependencies". Additionally:
* append_changed_indices now takes the king pos and stateinfo
explicitly, no more misleading pos parameter
* IndexList is removed in favor of a generic ValueList.
Feature transformer just instantiates the type it needs.
* The update cost and refresh requirement is deferred to the
feature set once again, but now doesn't go through the whole
FeatureSet machinery and just calls HalfKP directly.
* accumulator no longer has a singular dimension.
* The PS constants and the PieceSquareIndex array are made local
to the HalfKP feature set because they are specific to it and
DO differ for other feature sets.
* A few names are changed to more descriptive
Passed STC non-regression:
https://tests.stockfishchess.org/tests/view/608421dd95e7f1852abd2790
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 180008 W: 16186 L: 16258 D: 147564
Ptnml(0-2): 587, 12593, 63725, 12503, 596
closes https://github.com/official-stockfish/Stockfish/pull/3441
No functional change
This patch changes the pop_lsb() signature from Square pop_lsb(Bitboard*) to
Square pop_lsb(Bitboard&). This is more idomatic for C++ style signatures.
Passed a non-regression STC test:
LLR: 2.93 (-2.94,2.94) {-1.25,0.25}
Total: 21280 W: 1928 L: 1847 D: 17505
Ptnml(0-2): 71, 1427, 7558, 1518, 66
https://tests.stockfishchess.org/tests/view/6053a1e22433018de7a38e2f
We have verified that the generated binary is identical on gcc-10.
Closes https://github.com/official-stockfish/Stockfish/pull/3404
No functional change.
