================ @@ -45,3 +48,91 @@ Note: Both Chrome-tracing and speedscope tools might struggle with time traces a Luckily, in most cases the default max-steps boundary of 225 000 produces the traces of approximately that size for a single entry point. You can use ``-analyze-function=get_global_options`` together with ``-ftime-trace`` to narrow down analysis to a specific entry point. + + +Performance analysis using ``perf`` +=================================== + +`Perf <https://perfwiki.github.io/main/>`_ is an excellent tool for sampling-based profiling of an application. +It's easy to start profiling, you only have 2 prerequisites. +Build with ``-fno-omit-frame-pointer`` and debug info (``-g``). +You can use release builds, but probably the easiest is to set the ``CMAKE_BUILD_TYPE=RelWithDebInfo`` +along with ``CMAKE_CXX_FLAGS="-fno-omit-frame-pointer"`` when configuring ``llvm``. +Here is how to `get started <https://llvm.org/docs/CMake.html#quick-start>`_ if you are in trouble. + +.. code-block:: bash + :caption: Running the Clang Static Analyzer through ``perf`` to gather samples of the execution. + + # -F: Sampling frequency, use `-F max` for maximal frequency + # -g: Enable call-graph recording for both kernel and user space + perf record -F 99 -g -- clang -cc1 -nostdsysteminc -analyze -analyzer-constraints=range \ ---------------- Xazax-hun wrote:
I wonder if a simpler/smaller CSA invocation would suffice here for demonstration purposes. https://github.com/llvm/llvm-project/pull/126520 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
