Re: [PATCH 1/2 Resend] perf build: Update feature check for clang and llvm

[Ian Rogers]

On Wed, Aug 2, 2023 at 7:28 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> Em Tue, Jul 25, 2023 at 05:03:46PM +0200, Thomas Richter escreveu:
> > Perf build auto-detects features and packages already installed
> > for its build. This is done in directory tools/build/feature. This
> > directory contains small sample programs. When they successfully
> > compile the necessary prereqs in form of libraries and header
> > files are present.
> >
> > Such a check is also done for llvm and clang. And the checks fail.
> >
> > Fix this and update to the latest C++ standard and use the
> > new library provided by clang (which contains new packaging)
> > see this link for reference:
> >  https://fedoraproject.org/wiki/Changes/Stop-Shipping-Individual-Component-Libraries-In-clang-lib-Package
> >
> > Output before:
> >  # rm -f ./test-clang.bin; make test-clang.bin; ./test-clang.bin; \
> >       ll test-clang.make.output
> >  g++  -MD -Wall -Werror -o test-clang.bin test-clang.cpp \
> >               > test-clang.make.output 2>&1 -std=gnu++14 \
> >       -I/usr/include          \
> >       -L/usr/lib64            \
> >       -Wl,--start-group -lclangBasic -lclangDriver    \
> >         -lclangFrontend -lclangEdit -lclangLex        \
> >         -lclangAST -Wl,--end-group                    \
> >       -lLLVM-16       \
> >                       \
> >       > test-clang.make.output 2>&1
> >  make: *** [Makefile:356: test-clang.bin] Error 1
> >  -bash: ./test-clang.bin: No such file or directory
> >  -rw-r--r--. 1 root root 252041 Jul 12 09:56 test-clang.make.output
> >  #
> >
> > File test-clang.make.output contains many lines of unreferenced
> > symbols.
> >
> > Output after:
> >  # rm -f ./test-clang.bin; make test-clang.bin; ./test-clang.bin; \
> >       cat test-clang.make.output
> >  g++  -MD -Wall -Werror -o test-clang.bin test-clang.cpp \
> >        > test-clang.make.output 2>&1 -std=gnu++17     \
> >       -I/usr/include          \
> >       -L/usr/lib64            \
> >       -Wl,--start-group -lclang-cpp -Wl,--end-group   \
> >       -lLLVM-16       \
> >                       \
> >       > test-clang.make.output 2>&1
> >  #
>
> Thanks, tested and applied. Added some notes about needing to have
> 'llvm-devel' and 'clang-devel' installed to do the tests.
>
> - arnaldo
>
> > Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>

Note, the libllvm and clang support was needed for BPF events which I
propose removing in:
https://lore.kernel.org/lkml/20230810184853.2860737-1-irogers@xxxxxxxxxx/
(Sorry, forgot to add Thomas to the to/cc line of those changes).

Thanks,
Ian

> > ---
> >  tools/build/feature/Makefile | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> > index 2cd6dbbee088..3184f387990a 100644
> > --- a/tools/build/feature/Makefile
> > +++ b/tools/build/feature/Makefile
> > @@ -340,7 +340,7 @@ $(OUTPUT)test-jvmti-cmlr.bin:
> >       $(BUILD)
> >
> >  $(OUTPUT)test-llvm.bin:
> > -     $(BUILDXX) -std=gnu++14                                 \
> > +     $(BUILDXX) -std=gnu++17                                 \
> >               -I$(shell $(LLVM_CONFIG) --includedir)          \
> >               -L$(shell $(LLVM_CONFIG) --libdir)              \
> >               $(shell $(LLVM_CONFIG) --libs Core BPF)         \
> > @@ -348,17 +348,15 @@ $(OUTPUT)test-llvm.bin:
> >               > $(@:.bin=.make.output) 2>&1
> >
> >  $(OUTPUT)test-llvm-version.bin:
> > -     $(BUILDXX) -std=gnu++14                                 \
> > +     $(BUILDXX) -std=gnu++17                                 \
> >               -I$(shell $(LLVM_CONFIG) --includedir)          \
> >               > $(@:.bin=.make.output) 2>&1
> >
> >  $(OUTPUT)test-clang.bin:
> > -     $(BUILDXX) -std=gnu++14                                 \
> > +     $(BUILDXX) -std=gnu++17                                 \
> >               -I$(shell $(LLVM_CONFIG) --includedir)          \
> >               -L$(shell $(LLVM_CONFIG) --libdir)              \
> > -             -Wl,--start-group -lclangBasic -lclangDriver    \
> > -               -lclangFrontend -lclangEdit -lclangLex        \
> > -               -lclangAST -Wl,--end-group                    \
> > +             -Wl,--start-group -lclang-cpp -Wl,--end-group   \
> >               $(shell $(LLVM_CONFIG) --libs Core option)      \
> >               $(shell $(LLVM_CONFIG) --system-libs)           \
> >               > $(@:.bin=.make.output) 2>&1
> > --
> > 2.41.0
> >
>
> --
>
> - Arnaldo