Re: [Qemu-devel] [Bug 1594069] [NEW] SIMD instructions translated to scalar host instructions

[Peter Maydell]

On 19 June 2016 at 06:33, Timothy Pearson <address@hidden> wrote:
> Public bug reported:
>
> SIMD instructions inside the guest (NEON, MMX, SSE, SSE2, AVX) are
> translated to scalar instructions on the host instead of SIMD
> instructions.  It appears that there have been a few efforts to rectify
> this [1], and even a submitted patch series, but all discussion has
> effectively died out [2].
>
> I would like to see better SIMD performance on qemu, especially as
> non-x86 architectures are becoming widely used (e.g. ARM).

I agree it would be nice, but I'm not sure there's much benefit
from filing a bug about it. Bug reports don't magically become
code changes, and doing SIMD-to-SIMD is very difficult when
you need to support multiple host and guest architectures and
get all the details and corner cases correct. QEMU as it stands
isn't behaving wrongly.

thanks
-- PMM