Re: [Xen-devel] [PATCH for-4.9 v2 2/2] x86/dm: fix clang build

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Mon, Apr 10, 2017 at 03:27:35AM -0600, Jan Beulich wrote:
> >>> On 10.04.17 at 11:01, <roger.pau@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/hvm/dm.c
> > +++ b/xen/arch/x86/hvm/dm.c
> > @@ -408,9 +408,16 @@ static int dm_op(domid_t domid,
> >          {
> >              struct p2m_domain *p2m = p2m_get_hostp2m(d);
> >  
> > -            while ( read_atomic(&p2m->ioreq.entry_count) &&
> > -                    first_gfn <= p2m->max_mapped_pfn )
> > +            while ( first_gfn <= p2m->max_mapped_pfn )
> >              {
> > +                /*
> > +                 * NB: read_atomic cannot be used in the loop condition 
> > because
> > +                 * clang complains with: "'break' is bound to loop, GCC 
> > binds
> > +                 * it to switch", so move it inside of the loop instead.
> > +                 */
> > +                if ( !read_atomic(&p2m->ioreq.entry_count) )
> > +                    break;
> 
> How is this behavior of clang in line with the language spec, namely
> "A break statement terminates execution of the smallest enclosing
> switch or iteration statement"?

I don't think the condition itself is part of the iteration statement (AFAIK
the condition is the expression, not the statement).

Roger.

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