linux-kernel - Re: [PATCH 2/2] perf clang: Fixes for more recent LLVM/clang

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Message-ID: <CAP-5=fXK4f1G7ec05MM04hdxw53Ys2vQzzx6gvNpgVSQHDiuTw@mail.gmail.com>
Date:   Mon, 11 Oct 2021 19:17:03 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Fāng-ruì Sòng <maskray@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Leo Yan <leo.yan@...aro.org>,
        Michael Petlan <mpetlan@...hat.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH 2/2] perf clang: Fixes for more recent LLVM/clang

On Mon, Oct 11, 2021 at 4:49 PM Fāng-ruì Sòng <maskray@...gle.com> wrote:
>
> On Mon, Oct 11, 2021 at 4:35 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > On Mon, Oct 11, 2021 at 4:24 PM Ian Rogers <irogers@...gle.com> wrote:
> > >
> > > The parameters to two functions and the location of a variable have
> > > changed in more recent LLVM/clang releases.
> > >
> > > Tested with LLVM 6, 8, 9, 10 and 11.
> > >
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > > ---
> > >  tools/perf/util/c++/clang.cpp | 20 +++++++++++++-------
> > >  1 file changed, 13 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
> > > index c8885dfa3667..756200cb80b1 100644
> > > --- a/tools/perf/util/c++/clang.cpp
> > > +++ b/tools/perf/util/c++/clang.cpp
> > > @@ -44,7 +44,6 @@ createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
> > >                 "-triple", "bpf-pc-linux",
> > >                 "-fsyntax-only",
> > >                 "-ferror-limit", "19",
> > > -               "-fmessage-length", "127",
> >
> > Sorry, missed from the commit message. I removed this flag to format
> > output down to 127 columns as with clang 11 I see in perf test:
> >
> > 58: builtin clang support                                           :
> > 58.1: builtin clang compile C source to IR                          :
> > --- start ---
> > test child forked, pid 279307
> > error: unknown argument: '-fmessage-length'
> > 1 error generated.
> > test child finished with -1
> >
> > The flag isn't necessary for correct operation.
>
> Right, I changed the -cc1 option from Separate-form -fmessage-length
> to -fmessage-length= in 2020-03.
> -ferror-limit can be deleted as well.

Done in v2 (please consider adding Acked-by, Reviewed-by, etc).

> > Thanks,
> > Ian
> >
> > >                 "-O2",
> > >                 "-nostdsysteminc",
> > >                 "-nobuiltininc",
> > > @@ -55,7 +54,11 @@ createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
> > >                 "-x", "c"};
> > >
> > >         CCArgs.append(CFlags.begin(), CFlags.end());
> > > -       CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
> > > +       CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs
> > > +#if CLANG_VERSION_MAJOR >= 11
> > > +                                                        ,/*BinaryName=*/nullptr
> > > +#endif
> > > +                                                        );
> > >
> > >         FrontendOptions& Opts = CI->getFrontendOpts();
> > >         Opts.Inputs.clear();
> > > @@ -151,13 +154,16 @@ getBPFObjectFromModule(llvm::Module *Module)
> > >
> > >         legacy::PassManager PM;
> > >         bool NotAdded;
> > > -#if CLANG_VERSION_MAJOR < 7
> > > -       NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream,
> > > -                                                     TargetMachine::CGFT_ObjectFile);
> > > +       NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream
> > > +#if CLANG_VERSION_MAJOR >= 7
> > > +                                                      , /*DwoOut=*/nullptr
> > > +#endif
> > > +#if CLANG_VERSION_MAJOR < 10
> > > +                                                      , TargetMachine::CGFT_ObjectFile
> > >  #else
> > > -       NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream, nullptr,
> > > -                                                     TargetMachine::CGFT_ObjectFile);
> > > +                                                      , llvm::CGFT_ObjectFile
> > >  #endif
> > > +                                                      );
> > >         if (NotAdded) {
> > >                 llvm::errs() << "TargetMachine can't emit a file of this type\n";
> > >                 return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
> > > --
> > > 2.33.0.882.g93a45727a2-goog
> > >
>
> Related, does it make sense to drop CLANG_VERSION_MAJOR<7 support?

Arnaldo can likely best comment. Clang 6.0.1 was released on July 5th
2018 so it may still be in his build tests.

Thanks!
Ian