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

Peter Zijlstra
2021-06-14T10:18:54Z

On Mon, Jun 14, 2021 at 11:43:12AM +0200, Peter Zijlstra wrote:
> On Sun, Jun 13, 2021 at 11:07:26AM -0700, Bill Wendling wrote:
>
> > > > Now, for the "nointr" issue. I'll see if we need an additional change for that.
> > > >
> > > The GCOV implementation disables profiling in those directories where
> > > instrumentation would fail. We do the same. Both clang and gcc seem to
> > > treat the no_instrument_function attribute similarly.
>
> Both seem to emit instrumentation, so they're both, simliarly, *broken*.
>
> noinstr *MUST* disable all compiler generated instrumentation. Also see:
>
> https://lkml.kernel.org/r/20210527194448.3470080-1-elver@google.com
>
> I'll go mark GCOV support as BROKEN for x86.