Re: [XEN PATCH v2 1/3] xen: introduce STATIC_ASSERT_UNREACHABLE()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 6 Feb 2024, Jan Beulich wrote:
> On 06.02.2024 14:22, Jan Beulich wrote:
> > On 26.01.2024 11:05, Federico Serafini wrote:> --- 
> > a/xen/include/xen/compiler.h
> >> +++ b/xen/include/xen/compiler.h
> >> @@ -64,6 +64,13 @@
> >>  # define fallthrough        do {} while (0)  /* fallthrough */
> >>  #endif
> >>  
> >> +/*
> >> + * Add the following macro to check that a program point is considered
> >> + * unreachable by the static analysis performed by the compiler.
> >> + */
> >> +#define STATIC_ASSERT_UNREACHABLE() \
> >> +    asm ( ".error \"static assertion failed: unreachable\"" )
> > 
> > In the comment s/Add/Use/? The macro is there after all when this gets
> > committed. Overall maybe
> > 
> > "Use this macro at program points considered unreachable, to be checked
> >  by the compiler's static analysis."
> > 
> > ?
> > 
> > Also while asm()s without operands are implicitly volatile, I think it
> > would be a good idea to make that explicit nevertheless.
> > 
> > I'd be happy to adjust while committing, so long as you agree. If you
> > agree, and provided diagnostics resulting from this are useful (an
> > example would have been nice in the description):
> > Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Actually, having seen patch 2, I need to withdraw this right away.

To me it looks good enough but let's continue the discussion on patch
#2