On Fri, Sep 30, 2022 at 09:54:17PM +0000, Dave Thaler wrote: > [...] > > > +Also note that the modulo operation often varies by language when the > > > +dividend or divisor are negative, where Python, Ruby, etc. > > > +differ from C, Go, Java, etc. This specification requires that modulo > > > +use truncated division (where -13 % 3 == -1) as implemented in C, Go, > > > +etc.: > > > + > > > + a % n = a - n * trunc(a / n) > > > + > > > > Interesting bit of info, but I'm not sure how it relates to the ISA doc. > > It's because there's multiple definitions of modulo out there as the paragraph notes, > which differ in what they do with negative numbers. > The ISA defines the modulo operation as being the specific version above. > If you tried to implement the ISA in say Python and didn't know that, > you'd have a non-compliant implementation. Is it because the languages have weird rules to pick between signed vs unsigned mod? At least from llvm pov the smod and umod have fixed behavior.
