Date:   Sat, 12 Mar 2022 00:39:37 +0100
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Jiri Olsa <olsajiri@...il.com>
Cc:     Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Fangrui Song <maskray@...gle.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Leo Yan <leo.yan@...aro.org>, John Keeping <john@...anate.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Subject: Re: [PATCH] tools: feature/test-libperl.c: Sync PERL_EMBED_CCOPTS
 with perf

On Sat, Mar 12, 2022 at 12:30 AM Sedat Dilek <sedat.dilek@...il.com> wrote:
>
> On Fri, Mar 11, 2022 at 12:56 PM Jiri Olsa <olsajiri@...il.com> wrote:
> >
> > On Thu, Mar 10, 2022 at 07:19:09AM +0100, Sedat Dilek wrote:
> > > When trying to build perf with a LLVM/Clang toolchain people see errors
> > > when testing for libperl feature.
> > >
> > > Jiri reports:
> > >
> > > > I'm getting some other lto related error:
> > > >
> > > >         $ cat test-libperl.make.output
> > > >         clang-13: error: optimization flag '-ffat-lto-objects' is not supported [-Werror,-Wignored-optimization-argument]
> > > >
> > >
> > > The reason is PERL_EMBED_CCOPTS is defined in two places:
> > >
> > > tools/build/feature/Makefile
> > > tools/perf/Makefile.config
> > >
> > > As an result FLAGS_PERL_EMBED is set differently.
> > >
> > > For building perf '-ffat-lto-objects' is filtered-out:
> > >
> > > $ git grep ffat-lto-objects tools/perf/
> > > tools/perf/Makefile.config:  PERL_EMBED_CCOPTS := $(filter-out -flto=auto -ffat-lto-objects, $(PERL_EMBED_CCOPTS))
> > >
> > > Sync PERL_EMBED_CCOPTS in tools/build/feature/Makefile to fix this.
> > >
> > > For a minimal fix for Linux v5.17 this here was preferred by Arnaldo.
> > >
> > > Link: https://marc.info/?t=164646683300002&r=1&w=2
> > > Reported-by: Jiri Olsa <olsajiri@...il.com>
> > > Reported-by: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
> > > Tested-by: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
> > > Suggested-by: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
> > > Signed-off-by: Sedat Dilek <sedat.dilek@...il.com>
> > > ---
> > >  tools/build/feature/Makefile | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> > > index 1480910c792e..869073cf8449 100644
> > > --- a/tools/build/feature/Makefile
> > > +++ b/tools/build/feature/Makefile
> > > @@ -218,6 +218,7 @@ PERL_EMBED_LDOPTS = $(shell perl -MExtUtils::Embed -e ldopts 2>/dev/null)
> > >  PERL_EMBED_LDFLAGS = $(call strip-libs,$(PERL_EMBED_LDOPTS))
> > >  PERL_EMBED_LIBADD = $(call grep-libs,$(PERL_EMBED_LDOPTS))
> > >  PERL_EMBED_CCOPTS = `perl -MExtUtils::Embed -e ccopts 2>/dev/null`
> > > +PERL_EMBED_CCOPTS := $(filter-out -ffat-lto-objects, $(PERL_EMBED_CCOPTS))
> >
> > it looks like this is not enough, at least on fedora 35
> >
> > I had to add changes below on top of your patch, it fixed the perl
> > feature detection and perf build itself, but I'm still getting error
> > with perf/python.so:
> >
>
> Correct. This patch simply fixes the perl feature detection.
>
> >         $ CC=clang make JOBS=1
> >         ...
> >           GEN     python/perf.so
> >         python_ext_build/tmp/home/jolsa/kernel/linux-perf/tools/perf/util/python.o: file not recognized: file format not recognized
> >         clang-13: error: linker command failed with exit code 1 (use -v to see invocation)
> >         error: command 'clang' failed with exit status 1
> >         cp: cannot stat 'python_ext_build/lib/perf*.so': No such file or directory
> >
> > with:
> >
> >         $ file python_ext_build/tmp/home/jolsa/kernel/linux-perf/tools/perf/util/python.o
> >         python_ext_build/tmp/home/jolsa/kernel/linux-perf/tools/perf/util/python.o: LLVM IR bitcode
> >
> > do you get clean compile with python lang enabled?
> >
> > jirka
> >
> >
> > ---
> > diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> > index 869073cf8449..86df0fe11ee5 100644
> > --- a/tools/build/feature/Makefile
> > +++ b/tools/build/feature/Makefile
> > @@ -217,9 +217,9 @@ strip-libs = $(filter-out -l%,$(1))
> >  PERL_EMBED_LDOPTS = $(shell perl -MExtUtils::Embed -e ldopts 2>/dev/null)
> >  PERL_EMBED_LDFLAGS = $(call strip-libs,$(PERL_EMBED_LDOPTS))
> >  PERL_EMBED_LIBADD = $(call grep-libs,$(PERL_EMBED_LDOPTS))
> > -PERL_EMBED_CCOPTS = `perl -MExtUtils::Embed -e ccopts 2>/dev/null`
> > +PERL_EMBED_CCOPTS := $(shell perl -MExtUtils::Embed -e ccopts 2>/dev/null)
> >  PERL_EMBED_CCOPTS := $(filter-out -ffat-lto-objects, $(PERL_EMBED_CCOPTS))
> > -FLAGS_PERL_EMBED=$(PERL_EMBED_CCOPTS) $(PERL_EMBED_LDOPTS)
> > +FLAGS_PERL_EMBED  := $(PERL_EMBED_CCOPTS) $(PERL_EMBED_LDOPTS) -Wno-unused-command-line-argument -Wno-compound-token-split-by-macro
> >
> >  $(OUTPUT)test-libperl.bin:
> >         $(BUILD) $(FLAGS_PERL_EMBED)
> > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > index 96ad944ca6a8..38b0b0e7a168 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -778,7 +778,7 @@ else
> >    PERL_EMBED_LIBADD = $(call grep-libs,$(PERL_EMBED_LDOPTS))
> >    PERL_EMBED_CCOPTS = $(shell perl -MExtUtils::Embed -e ccopts 2>/dev/null)
> >    PERL_EMBED_CCOPTS := $(filter-out -specs=%,$(PERL_EMBED_CCOPTS))
> > -  PERL_EMBED_CCOPTS := $(filter-out -flto=auto -ffat-lto-objects, $(PERL_EMBED_CCOPTS))
> > +  PERL_EMBED_CCOPTS := $(filter-out -flto=auto -ffat-lto-objects, $(PERL_EMBED_CCOPTS)) -Wno-unused-command-line-argument -Wno-compound-token-split-by-macro
> >    PERL_EMBED_LDOPTS := $(filter-out -specs=%,$(PERL_EMBED_LDOPTS))
> >    FLAGS_PERL_EMBED=$(PERL_EMBED_CCOPTS) $(PERL_EMBED_LDOPTS)
> >
>
> I fixed that differently by (see [1]),
>
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -213,7 +213,7 @@ endif
>
> # Treat warnings as errors unless directed not to
> ifneq ($(WERROR),0)
> -  CORE_CFLAGS += -Werror
> +  CORE_CFLAGS += -Werror -Wno-compound-token-split-by-macro
>   CXXFLAGS += -Werror
>   HOSTCFLAGS += -Werror
> endif
>
> This was sufficient here to build perf successfully.
> And maybe ifdef-ed for clang?
>
> But all this is a follow-up?
>
> [1] https://lore.kernel.org/lkml/CA+icZUUCO+gOPLZumu_rTOJz1_v7gRRYVzzEZ+RZPOZBmkqCQg@mail.gmail.com/
>
> > diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
> > index 483f05004e68..cfbb03babf63 100644
> > --- a/tools/perf/util/setup.py
> > +++ b/tools/perf/util/setup.py
> > @@ -43,7 +43,7 @@ class install_lib(_install_lib):
> >
> >  cflags = getenv('CFLAGS', '').split()
> >  # switch off several checks (need to be at the end of cflags list)
> > -cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls', '-DPYTHON_PERF' ]
> > +cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls', '-Wno-ignored-optimization-argument', '-DPYTHON_PERF' ]
> >  if not cc_is_clang:
> >      cflags += ['-Wno-cast-function-type' ]
> >
>
> Cannot say much to that.
>
> Do we want to fix perf building with LLVM/Clang for Linux v5.17 final or later?
> Arnaldo?
>

Attached is the patch I use to build perf.
( As said in the initial report I wanted to test perf with -std=gnu11. )
( Cannot say much if this related to perl v5.34 only. )

- Sedat -

[1] https://lore.kernel.org/lkml/CA+icZUWHd4VTKNwBtuxt9-fHoiYV+Q7tQ809Cn83k8sbQ_uNHw@mail.gmail.com/

View attachment "0001-perf-Fix-libperl-support-with-clang-and-perl-v5.34.patch" of type "text/x-patch" (1405 bytes)

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