Re: qemu-user: avoid allocations to convert stuff when not necessary

[Michael Tokarev]

09.04.2023 19:27, Richard Henderson пишет:
> On 4/9/23 01:52, Michael Tokarev wrote:
> > Hi!
> >
> > In the qemu-user case, we allocate various structures and arrays
> > for conversion of data between host and guest byte orders and sizes.
> > But it is actually not necessary to do such allocation when the
> > *size* is the same, and only byte order is different, because the
> > conversion can be done in-place.  Does it make any sense to avoid'
> > allocations in such cases?
>
> Alignment can also change.  This is especially visible with m68k guest, where 
> even 'int' is 2-byte aligned.

I didn't think about the alignment. So such optimization has less and
less chances to happen. I see.

> So, no.  It's best to just allocate and convert always.

Yes, this makes good sense.

Thanks!

/mjt