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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 14 Jan 2019 14:00:51 -0800
Message-ID: <CAKwvOdnfMFmDm-DdbFEZxQdXzP47mnZ27hWw5vqe8Lqh21hBhg@mail.gmail.com>
Subject: Re: [PATCH 0/4] gcov: add Clang support
To:     Tri Vo <trong@android.com>
Cc:     oberpar@linux.ibm.com, Greg Hackmann <ghackmann@android.com>,
        LKML <linux-kernel@vger.kernel.org>, kernel-team@android.com
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On Mon, Jan 14, 2019 at 1:53 PM Tri Vo <trong@android.com> wrote:
>
> On Mon, Jan 14, 2019 at 1:33 PM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > On Mon, Jan 14, 2019 at 1:04 PM Tri Vo <trong@android.com> wrote:
> > >
> > > This patch series adds Clang supoprt for gcov.
> > >
> > > Patch 1 refactors existing code in preparation for Clang support. Patches
> > > 2-3 implement necessary LLVM runtime hooks and gcov kernel interfaces.
> > > Patch 4 simplifies config selection.
> > >
> > > Greg Hackmann (2):
> > >   gcov: clang: move common gcc code into gcc_base.c
> > >   gcov: clang support
> > >
> > > Nick Desaulniers (1):
> > >   gcov: clang: link/unlink profiling data set.
> > >
> > > Tri Vo (1):
> > >   gcov: clang: pick GCC vs Clang format depending on compiler
> >
> > Thanks for sending Tri!  Doesn't the output format require llvm-cov, or no?
>
> Yes, .gcda files generated by a Clang-built kernel could only be
> parsed by llvm-cov, but not gcc gcov (at least in my local tests).
>
> llvm-cov documentation also indicates that GCC and LLVM gcov tools are
> not necessarily compatible. "[llvm-cov] is compatible with the gcov
> tool from version 4.2 of GCC and may also be compatible with some
> later versions of gcov."
> https://llvm.org/docs/CommandGuide/llvm-cov.html

Thanks, that's good to know for folks looking to help test.  Note to
reviewers that we're actively using this patch set on arm64 devices.

-- 
Thanks,
~Nick Desaulniers