Re: [RFC] LKMM: Add volatile_if()

[Segher Boessenkool]

On Fri, Jun 04, 2021 at 01:31:48PM +0200, Peter Zijlstra wrote:
> On Fri, Jun 04, 2021 at 11:44:00AM +0100, Will Deacon wrote:
> > > +{
> > > +	asm_volatile_goto("cbnz %0, %l[l_yes]"
> > > +			  : : "r" (cond) : "cc", "memory" : l_yes);
> > > +	return 0;
> > > +l_yes:
> > > +	return 1;
> > > +}
> > 
> > nit: you don't need the "cc" clobber here.
> 
> Yeah I know, "cc" is implied.

It isn't needed at all here.  cbnz does not write to the condition
register.  Neither does it change or access memory, but the "memory"
clobber is to force a false dependency.  Writing "cc" as well looks a
bit confusing, given that.


Segher