On Friday, October 25, 2019, Taylor Simpson <tsimpson@quicinc.com> wrote:

> We would like inform the you that we will be doing a talk at the KVM Forum
> next week on QEMU for Qualcomm Hexagon.  Alessandro Di Federico, Niccolo
> Izzo, and I have been working independently on implementations of the
> Hexagon target.  We plan to merge the implementations, have a community
> review, and ultimately have Hexagon be an official target in QEMU.  Our
> code is available at the links below.
>
> *https://github.com/revng/qemu-hexagon
> <https://github.com/revng/qemu-hexagon>*
>
> *https://github.com/quic/qemu <https://github.com/quic/qemu>*
>
> If anyone has any feedback on the code as it stands today or guidance on
> how best to prepare it for review, please let us know.
>
>
>

Hi, Taylor, Niccolo (and Alessandro too).

I didn't have a chance to take a look at neither the code nor the docs, but
I did attend you presentation at KVM Forum, and I found it superb and
attractive, one of the best on the conference, if not the very best.

I just have a couple of general questions:

- Regarding the code you plan to upstream, are all SIMD instructions
implemented via tcg API, or perhaps some of them remain being implemented
using helpers?

- Most of SIMD instructions can be viewed simply as several paralel
elementary operations. However, for a given SIMD instruction set, usually
not all of them fit into this pattern. For example, "horizontal add"
(addind data elements from the same SIMD register), various
"pack/unpack/interleave/merge" operations, and more general
"shuffle/permute" operations as well (here I am not sure which of these are
included in Hexagon SIMD set, but there must be some). How did you deal
with them?

- What were the most challenging Hexagon SIMD instructions you came accross
while developing your solution?

Sincerely,
Aleksandar





> Thanks,
>
> Taylor
>