Re: [PATCH] crypto: blake2b - Fix clang optimization for ARMv7-M

[Nathan Chancellor]

On Fri, May 08, 2020 at 11:31:07PM +0200, Arnd Bergmann wrote:
> On Wed, May 6, 2020 at 7:12 AM Nathan Chancellor
> <natechancellor@xxxxxxxxx> wrote:
> > > -
> > > +#ifdef CONFIG_CC_IS_CLANG
> >
> > Given your comment in the bug:
> >
> > "The code is written to assume no loops are unrolled"
> >
> > Does it make sense to make this unconditional and take compiler
> > heuristics out of it?
> >
> > > +#pragma nounroll /* https://bugs.llvm.org/show_bug.cgi?id=45803 */
> > > +#endif
> > >       for (i = 0; i < 8; ++i)
> > >               S->h[i] = S->h[i] ^ v[i] ^ v[i + 8];
> 
> No, that would not work, as gcc does not support this pragma.
> 
>         Arnd

Ah fair enough.

Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>