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ridiculousfish / libdivide

Official git repository for libdivide: optimized integer division
http://libdivide.com
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Use __umulh()/__mulh() on MSVC #19

Closed zekyll closed 8 years ago

zekyll commented 8 years ago

The functions libdividemullhi_u64/libdivide__mullhi_s64 can be implemented much faster on MSVC with umulh()/__mulh() intrinsics. They have the exact same signature so it's a very easy modification and should be supported on all MSVC versions.

ridiculousfish commented 8 years ago

Cool! Did you happen to check how MSVC is currently compiling these - i.e. are the intrinsics actually faster?

zekyll commented 8 years ago

It does compile to single instruction on x64 at least and it is significantly faster.

ridiculousfish commented 8 years ago

Oh I just noticed what the current implementation is. Yes, let's switch to these where available.