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

[Jacob Lifshay]

On Wed, Sep 11, 2019, 04:43 lkcl <luke.leighton at gmail.com> wrote:

>
> https://gpuopen.com/wp-content/uploads/2019/08/RDNA_Shader_ISA_5August2019.pdf
>
>>
> someone kindly (privately) pointed out the above - table 22, p44 - and
> apart from updating to include F16 and in some cases F64, the opcodes
> provided *have not changed* in 11 years since the R500.
>

looking through it again, the sin/cos instructions for Radeon are actually
sin(x * 2 * pi) and cos(x * 2 * pi), reinforcing my idea to just implement
sinpi/cospi for GPU applications, though there is a V_TRIG_PREOP_F64
instruction to accelerate argument reduction for f64 sin/cos.

Jacob