Lichess maintains some patches on top of SF dev to get it working with Emscripten. This PR moves some of these patches into SF and adds WASM to CI. It also adds a few changes in places where the x86 intrinsics don't cleanly map onto WebAssembly SIMD instructions; otherwise, we use Emscripten's x86 compatibility layer and take SSE4.1 code paths.
Summary of the compatibility changes:
- Define `wasm32` and `wasm32-relaxed-simd` targets.
- We don't support wasm without SIMD; it'd be a waste of time.
- Add option to disable TBs
- This is required because `tbprobe.cpp` pulls in `mmap`. This option can be used on any target, of course, but it's only enabled by default for wasm.
- Add compilation job + test to CI
And the changes for performance:
- Disable atomics for shared history on wasm
- Atomics are always `seq_cst` there, which can be quite slow (even on the x86, stores are locked `xchg [mem], reg`)
- Add SSE code path to `get_changed_pieces`, modeled after the AVX2 path
- `_mm_mulhi_epi16` has a complicated emulation sequence, so for the pairwise multiplication, use an approach similar to the NEON impl.
- __int128 is gets lowered to runtime functions on wasm, so use the fallback impl for `mul_hi64`
- V8 does a poor job with the NNZ finding, so use a slightly different sequence there
- Add relaxed simd support for `m128_dpbusd`.
Some local perf figures (single-threaded speedtest):
```
wasm
Nodes/second : 902523
sse4.1
Nodes/second : 1155380
avx512icl
Nodes/second : 1676184
```
Further avenues to explore:
- Optimize for performance under V8's experimental AVX revectorizer (Currently it's about +10% in my testing, but could definittely be more)
- Branch hinting. For example, run bench while collecting branch frequency info, then inject it late in the WASM compilation pipeline. I tried this locally and it didn't help much, but maybe I'm missing something.
- PGO. Gives +1.5% NPS locally, but hard to integrate with WASM compilation wrokflows
closes https://github.com/official-stockfish/Stockfish/pull/6875
No functional change
WINE_PATH started as a Wine-specific knob, but it’s now used more generally
as a command prefix to run the built engine under wrappers
like Intel SDE, qemu-user, etc.
- Add RUN_PREFIX as the supported “run wrapper/prefix” variable in Makefile
- Set WINE_PATH as a deprecated alias
- Update CI and scripts to use RUN_PREFIX
closes https://github.com/official-stockfish/Stockfish/pull/6500
No functional change
gcc 9.3
clang 10
using unsupported compiler versions will generate an error,
older version might miscompile SF
CI: improves output on failed bench output
closes https://github.com/official-stockfish/Stockfish/pull/6032
No functional change
use a fixed compiler on Linux and Windows (right now gcc 11).
build avxvnni on Windows (Linux needs updated core utils)
build x86-32 on Linux (Windows needs other mingw)
fix a Makefile issue where a failed PGOBENCH would not stop the build
reuse the WINE_PATH for SDE as we do for QEMU
use WINE_PATH variable also for the signature
verify the bench for each of the binaries
do not build x86-64-avx2 on macos
closes https://github.com/official-stockfish/Stockfish/pull/4682
No functional change
Perform more complex verification and validation.
- signature.sh : extract and optionally compare Bench/Signature/Node count.
- perft.sh : verify perft counts for a number of positions.
- instrumented.sh : run a few commands or uci sequences through valgrind/sanitizer instrumented binaries.
- reprosearch.sh : verify reproducibility of search.
These script can be used from directly from the command line in the src directory.
Update travis script to use these shell scripts.
No functional change.
