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

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:

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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.

https://lkml.kernel.org/r/YMcssV/n5IBGv4f0@hirez.programming.kicks-ass.net