Hi, On 16 February 2017 at 09:06, <ycollette.nos...@free.fr> wrote: > Hello, > > My question is related to CMAKE_*_FLAGS. > I've got a project under linux fedora 24 and, in release mode, this project > compiles with the -O2 flag. > But when I switched to other platform (ubuntu, fedora 16 - I now this one is > quite old but I need to compile on this platform), this default optimization > flag changes. On some platform, it's -O3. > And because with -O3 flag some "risky" optimizations are enabled, my project > hangs ...
You can find CMake's defaults for gcc/clang in /usr/share/cmake-<version>/Modules/Compiler/GNU.cmake where <version> is your CMake version. E.g. https://github.com/Kitware/CMake/blob/master/Modules/Compiler/GNU.cmake You'll see lines like ``` string(APPEND CMAKE_${lang}_FLAGS_INIT " ") string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -g") string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -Os -DNDEBUG") string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O3 -DNDEBUG") string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O2 -g -DNDEBUG") ``` It's possible that the defaults changed at some point but I would be really surprised by this. Are you sure you weren't doing a RELWITHDEBINFO build on one system and a RELEASE build on the other? It is possible to override these defaults by writing an overrides file (example [1]) and then using those overrides before the `project()` declaration in your root `CMakeLists.txt` file. Here's an example [2]. So if you need fine grained control over the optimization level used for different build types then I suggest you use overrides. [1] https://github.com/delcypher/fp-bench/blob/ebc8f939500b6ec28e6530f65273df8bfb122970/cmake/c_flags_override.cmake [2] https://github.com/delcypher/fp-bench/blob/ebc8f939500b6ec28e6530f65273df8bfb122970/CMakeLists.txt#L5 HTH, Dan. -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake
