Re: [Qemu-devel] [PATCH] x86_64: optimise muldiv64 for x86_64 architecture

[Peter Maydell]

On 9 January 2015 at 11:24, Paolo Bonzini <address@hidden> wrote:
> On 09/01/2015 12:04, Frediano Ziglio wrote:
>> I think that I'll write two patches. One implementing using the int128
>> as you suggested (which is much easier to read that current one and
>> assembly ones) that another for x86_64 optimization.
>
> Right, that's even better.

Personally I would prefer we didn't write inline assembly
functions if we can avoid them. So I'd rather see an int128
version, and if the compiler doesn't do a good enough job
then go talk to the compiler folks to improve things.

> Out of curiosity, have you seen it in some profiles?

I would absolutely want to see significant perf uplift on
a real workload before we start putting inline asm into
qemu-common.h...

-- PMM