[libre-riscv-dev] [isa-dev] Re: FP transcendentals (trigonometry, root/exp/log) proposal

[Andrew Waterman]

On Thu, Aug 8, 2019 at 8:12 PM lkcl <luke.leighton at gmail.com> wrote:

> On Thursday, August 8, 2019 at 10:14:58 PM UTC+8, andrew wrote:
>
> > As I mentioned earlier, an instruction being useful is not by itself a
> justification for adding it to the ISA. Where’s the quantitative case for
> these instructions?
>
> 3D is a Billion dollar mass volume market, proprietary GPUs are going
> after mass volume, inherently excluding the needs of (profitable) long-tail
> markets.


That’s a business justification, not an architectural one, and in any case
it’s a justification for different instructions than the ones you’ve
proposed. The market you’re describing isn’t populated with products that
have ISA-level support for correctly rounded transcendentals; they favor
less accurate operations or architectural support for approximations and
iterative refinement.


>
> L.
>
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