RISC-V assembly patch for FFmpeg by SiFive

[camel-cdr]

Why did they use `vslidedown v1, v2, 1` instead of `vslide1down v1, v2, x0`?

[brucehoult]

Heh. The use of `vslidedown` was also what drew my eyes. But in my case the thoughts were "that's supposed to be a pretty slow instruction, included mostly for debuggers to use".

I wonder if they've run it on any actual RVV 1.0 hardware. I guess probably in an FPGA.

Tempted to convert that to RVV 0.7.1 and submit it...