Very interesting, Gareth !
Is the div-by-7 related to 2 to the 3rd ? If yes, is it possible to design a
div-by-3 with similar magics ?
Cheers, Ched'
Le 03.09.21 à 15:35, J. Gareth Moreton via fpc-devel a écrit :
Hey Marģers,
So I've been experimenting with your suggestion, and it looks like a resounding success! I added some
new tests to the "bdiv" bench test to see how it performs. 16-bit multiplications don't get improved as
well as they could be on x86_64 because the intermediate values are all extended to 32-bit, but you can
still see a massive improvement on all the unsigned divisions by 7.
I'm currently running the test suite for i386-win32 and x86_64-win64, then will implement the same system
for AArch64. Thanks so much for spotting the improvement.
Gareth aka. Kit
P.S. I still need to work on the signed modulus at some point.
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