Re: [Minios-devel] [UNIKRAFT PATCHv4 16/43] uk/arch: Implement ukarch_find_lsbit for Arm64

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 13/07/18 10:20, Wei Chen wrote:
> > > +#ifndef __UKARCH_ATOMIC_H__
> > > +#error Do not include this header directly
> > > +#endif
> > > +
> > For finding the lsbit shouldn't we use the builtin function
> > __builtin_ffs, __builtin_ffsl?
AFAICT __builtin_ffs is GNU-ism. Do we really want to tie ourself to it? 
Also, do you know if that is supported correctly on all GCC versions we 
targets?
> >
> When I was implementing the ukarch_find_lsbit, I found both Arm32 and
> X86_64 were not using the builtin-functions. X86_64 is using "bsfq",
> Arm32 is using the same instructions as Arm64.
To be honest, I would keep the implement as it is.

Cheers,

--
Julien Grall

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