Re: Re: [PATCH v3 1/3] bits: introduce fixed-type genmasks

[Yury Norov]

On Wed, Feb 21, 2024 at 03:59:06PM -0600, Lucas De Marchi wrote:
> On Wed, Feb 21, 2024 at 11:04:22PM +0200, Andy Shevchenko wrote:
> > On Wed, Feb 21, 2024 at 10:30:02PM +0200, Dmitry Baryshkov wrote:
> > > On Thu, 8 Feb 2024 at 09:45, Lucas De Marchi <lucas.demarchi@xxxxxxxxx> wrote:
> > 
> > ...
> > 
> > > > +#define BITS_PER_TYPE(type)    (sizeof(type) * BITS_PER_BYTE)
> > 
> > Can sizeof() be used in assembly?
> > 
> > ...
> > 
> > > > -#define __GENMASK(h, l) \
> > > > -       (((~UL(0)) - (UL(1) << (l)) + 1) & \
> > > > -        (~UL(0) >> (BITS_PER_LONG - 1 - (h))))
> > > > -#define GENMASK(h, l) \
> > > > -       (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
> > 
> > > > +#define __GENMASK(t, h, l) \
> > > > +       (GENMASK_INPUT_CHECK(h, l) + \
> > > > +        (((t)~0ULL - ((t)(1) << (l)) + 1) & \
> > > > +        ((t)~0ULL >> (BITS_PER_TYPE(t) - 1 - (h)))))
> > 
> > Nevertheless, the use ~0ULL is not proper assembly, this broke initial
> > implementation using UL() / ULL().
> 
> indeed.
> 
> > 
> > 
> > > > -#define __GENMASK_ULL(h, l) \
> > > > -       (((~ULL(0)) - (ULL(1) << (l)) + 1) & \
> > > > -        (~ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
> > > > -#define GENMASK_ULL(h, l) \
> > > > -       (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
> > 
> > Ditto.
> 
> problem here seems actually because of the cast to the final type. My
> previous impl was avoiding that, but was too verbose compared to this.
> 
> I will look at reverting this.
> 
> Lucas De Marchi

The fix is quite straightforward. Can you consider the following
patch? I tested it for C and x86_64 asm parts, and it compiles well.

Thanks,
Yury