Re: [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power of 2

["Radim Krčmář" <rkrcmar@redhat.com>]

2015-03-05 12:57+0800, Dongsheng Song:
> On Wed, Mar 4, 2015 at 10:30 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> > +/* round up to the nearest power of 2 (0 if overflow) */
> > +uint64_t pow2ceil(uint64_t value)
> > +{
> > +    uint8_t nlz = clz64(value);
> > +
> > +    if (is_power_of_2(value)) {
> > +        return value;
> > +    }
> 
> please call clz64 after is_power_of_2.

All callers under clz64() are inline, so the optimizer can see that
there are no side effects and move the code if it would be faster;
I thought that separating it would only make the code uglier, because
QEMU doesn't allow lazy declarations ...

Markus had another design issue with this patch, so I'll send a v2 after
reaching the conclusion there.

Thanks.