Dev Builds » 20190711-0930

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NCM plays each Stockfish dev build 20,000 times against Stockfish 14. This yields an approximate Elo difference and establishes confidence in the strength of the dev builds.


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Commit ID fa1a2a0667ff81f04e94cab078c50c2d51f4cb5e
Author Daniel Axtens
Date 2019-07-11 09:30:09 UTC
Enable popcount and prefetch for ppc-64 PowerPC has had popcount instructions for a long time, at least as far back as POWER5 (released 2004). Enable them via a gcc builtin. Using a gcc builtin has the added bonus that if compiled for a processor that lacks a hardware instruction, gcc will include a software popcount implementation that does not use the instruction. It might be slower than the table lookups (or it might be faster) but it will certainly work. So this isn't going to break anything. On my POWER8 VM, this leads to a ~4.27% speedup. Fir prefetch, the gcc builtin generates a 'dcbt' instruction, which is supported at least as far back as the G5 (2002) and POWER4 (2001). This leads to a ~5% speedup on my POWER8 VM. No functional change
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