Re: vwredsum


Bruce Hoult
 

As a 2*SEW scalar from element 0 of vs1 is added to the sum of the various SEW elements in vs2, even a vector of length 1 can cause overflow.


On Fri, Sep 17, 2021 at 12:43 PM Earl Killian <earl.killian@...> wrote:
If the vector operand to an integer vwredsum is long enough, 2*SEW will not be large enough to contain the result. I would interpret the spec to suggest that the low 2*SEW bits are written to the destination (there is not mention of saturation), but it seems like it deserves a mention, if only to encourage software to think about precision and vector length.






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