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

From: James Clark
Date: Tue Sep 10 2024 - 11:12:01 EST




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.