Re: [RFC] LKMM: Add volatile_if()

Segher Boessenkool
2021-06-07T14:21:24Z

On Mon, Jun 07, 2021 at 12:52:15PM +0200, Peter Zijlstra wrote:
> On Sun, Jun 06, 2021 at 03:26:16PM -0500, Segher Boessenkool wrote:
> > I am saying that if you depend on that some C code you write will result
> > in some particular machine code, without actually *forcing* the compiler
> > to output that exact machine code, then you will be disappointed. Maybe
> > not today, and maybe it will take years, if you are lucky.
> >
> > (s/forcing/instructing/ of course, compilers have feelings too!)
>
> And hence the request for a language extension. Both compilers have a
> vast array of language extensions that are outside of the C spec (thank
> you!), so can we please get one more?

I don't see why not? It will need to be well-defined, so that it *can*
be implemented. And ideally it will be useful for other applications as
well. Finally, it should "play nice" with other extensions and language
features.

Segher