Re: [PATCH v9] pgo: add clang's Profile Guided Optimization infrastructure

Nick Desaulniers
2021-06-14T18:09:28Z

On Mon, Jun 14, 2021 at 9:23 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Jun 14, 2021 at 05:35:45PM +0200, Peter Zijlstra wrote:
> > On Mon, Jun 14, 2021 at 08:26:01AM -0700, Kees Cook wrote:
> > > So, AFAICT, the original blocking issue ("PGO does not respect noinstr")
> > > is not actually an issue (noinstr contains notrace, which IS respected
> > > by PGO[2]), I think this is fine to move forward.
> >
> > It is *NOT*: https://godbolt.org/z/9c7xdvGd9
> >
> > Look at how both compilers generate instrumentation in the no_instr()
> > function.
>
> Well that's disappointing. I'll put this on hold until Clang can grow an
> appropriate attribute (or similar work-around). Thanks for catching
> that.

Cross referencing since these two threads are related.
https://lore.kernel.org/lkml/CAKwvOdmPTi93n2L0_yQkrzLdmpxzrOR7zggSzonyaw2PGshApw@mail.gmail.com/
--
Thanks,
~Nick Desaulniers