Re: [PATCH 1/2] perf build: Autodetect minimum required llvm-dev version

[James Clark]

On 9/10/24 15:27, Quentin Monnet wrote:
> 2024-09-10 15:04 UTC+0100 ~ James Clark <james.clark@xxxxxxxxxx>
> > The new LLVM addr2line feature requires a minimum version of 13 to
> > compile. Add a feature check for the version so that NO_LLVM=1 doesn't
> > need to be explicitly added. Leave the existing llvm feature check
> > intact because it's used by tools other than Perf.
> >
> > This fixes the following compilation error when the llvm-dev version
> > doesn't match:
> >
> >    util/llvm-c-helpers.cpp: In function 'char* 
> > llvm_name_for_code(dso*, const char*, u64)':
> >    util/llvm-c-helpers.cpp:178:21: error: 
> > 'std::remove_reference_t<llvm::DILineInfo>' {aka 'struct 
> > llvm::DILineInfo'} has no member named 'StartAddress'
> >      178 |   addr, res_or_err->StartAddress ? 
> > *res_or_err->StartAddress : 0);
> >
> > Fixes: c3f8644c21df ("perf report: Support LLVM for addr2line()")
> > Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
> > ---
> >   tools/build/Makefile.feature           |  2 +-
> >   tools/build/feature/Makefile           |  9 +++++++++
> >   tools/build/feature/test-llvm-perf.cpp | 14 ++++++++++++++
> >   tools/perf/Makefile.config             |  6 +++---
> >   4 files changed, 27 insertions(+), 4 deletions(-)
> >   create mode 100644 tools/build/feature/test-llvm-perf.cpp
> >
> > diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
> > index 0717e96d6a0e..427a9389e26c 100644
> > --- a/tools/build/Makefile.feature
> > +++ b/tools/build/Makefile.feature
> > @@ -136,7 +136,7 @@ FEATURE_DISPLAY ?=              \
> >            libunwind              \
> >            libdw-dwarf-unwind     \
> >            libcapstone            \
> > -         llvm                   \
> > +         llvm-perf              \
>
> Hi! Just a quick question, why remove "llvm" from the list, here?
>
> Quentin

Just because with respect to the linked fixes: commit, it wasn't 
actually there before. It was added just for addr2line so it should 
probably be llvm-perf rather than the generic one.

But yes we can add llvm output if it's useful, but could probably be a 
separate commit.