Re: PROPOSAL: Extend inline asm syntax with size spec

Ingo Molnar
2018-10-10T06:35:43Z

* Segher Boessenkool <segher@kernel.crashing.org> wrote:

> On Mon, Oct 08, 2018 at 11:07:46AM +0200, Richard Biener wrote:
> > On Mon, 8 Oct 2018, Segher Boessenkool wrote:
> > > On Sun, Oct 07, 2018 at 03:53:26PM +0000, Michael Matz wrote:
> > > > On Sun, 7 Oct 2018, Segher Boessenkool wrote:
> > > > > On Sun, Oct 07, 2018 at 11:18:06AM +0200, Borislav Petkov wrote:
> > > > > > Now, Richard suggested doing something like:
> > > > > >
> > > > > > 1) inline asm ("...")
> > > > >
> > > > > What would the semantics of this be?
> > > >
> > > > The size of the inline asm wouldn't be counted towards the inliner size
> > > > limits (or be counted as "1").
> > >
> > > That sounds like a good option.
> >
> > Yes, I also like it for simplicity. It also avoids the requirement
> > of translating the number (in bytes?) given by the user to
> > "number of GIMPLE instructions" as needed by the inliner.
>
> This patch implements this, for C only so far. And the syntax is
> "asm inline", which is more in line with other syntax.
>
> How does this look?

Cool, thanks for implementing this!

In the kernel we'd likely wrap this in some "asm_inline()" type of construct to be
compatible with older toolchains and other compilers.

Thanks,

Ingo