[Libre-soc-isa] [Bug 213] SimpleV Standard writeup needed

bugzilla-daemon at libre-soc.org bugzilla-daemon at libre-soc.org
Mon Jan 18 00:47:42 GMT 2021


https://bugs.libre-soc.org/show_bug.cgi?id=213

--- Comment #115 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Jacob Lifshay from comment #114)

> yup, for integer ops only (though fp max and min would also work, depending
> on the exact IEEE754 function used). anything that is an associative
> operator.

ah that was the word i couldn't remrmber

> >  things like SUB, DIV, those
> > are a little weird.
> 
> And the majority of floating-point ops.
> 
> though integer sub could be parallelized by doing negations and a parallel
> add-reduce.

yeah i pointed this out

> > > > * vector tree-based map-reduce O(VL log VL)
> > > 
> > > parallel reduction
> > 
> > yep nice point, noted.
> 
> it just occurred to me that when context-switching in the middle of a
> parallel-reduction, the vstart register is not actually the starting index,
> so we should call it resume-step (the step at which the next SV instruction
> resumes its progress) or something.

hmm hmm good point.  more descriptive/meaningful. needs to be in the SVSTATE
SPR page

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