[AArch64][Spec2017]Question about mlow-precision-div optimization.

Wilco Dijkstra Wilco.Dijkstra@arm.com
Wed Mar 4 13:26:00 GMT 2020


Hi Richard,

> The suggestion was to have a parameter to control the number of steps,
> rather than always use the values that are currently hard-coded into
> aarch64.c.
>
> That sounds OK in principle.  It would fix one of the downsides of the
> current code, in which users can force reciprocal approximation to be
> used at low precision, but can't force it to be used at the precisions
> normally chosen by -mtune.

Well there are only 2 possible settings, so I don't see how a param would be
reasonable... However given there is no performance improvement for the low
precision versions, what is the point of adding new options for the even slower,
higher precision variant?!?

Cheers,
Wilco



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