diff --git a/CHANGELOG.md b/CHANGELOG.md index 4f3aaa9e..51f1df82 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -49,6 +49,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/). - LTO support: Allow using LTO/IPO by setting `FSFW_ENABLE_LTO=1`. CMake is able to detect whether the user compiler supports IPO/LPO. LTO is on by default now. Most modern compilers support it, can make good use of it and it usually makes the code faster and/or smaller. + After some more research: + Enabling LTO will actually cause the compiler to only produce thin LTO by adding + `-flto -fno-fat-lto-objects` to the compiler options. I am not sure this is an ideal choice + because if an application linking against the FSFW does not use LTO, there can be compile + issues (e.g. observed when compiling the FSFW tests without LTO). This is a known issue as + can be seen in the multiple CMake issues for it: + - https://gitlab.kitware.com/cmake/cmake/-/issues/22913, + - https://gitlab.kitware.com/cmake/cmake/-/issues/16808, + - https://gitlab.kitware.com/cmake/cmake/-/issues/21696 + Easiest solution for now: Keep this option OFF by default. PR: https://egit.irs.uni-stuttgart.de/fsfw/fsfw/pulls/616 - Linux HAL: Add wiretapping option for I2C. Enabled with `FSFW_HAL_I2C_WIRETAPPING` defined to 1 - Dedicated Version class and constant `fsfw::FSFW_VERSION` containing version information diff --git a/CMakeLists.txt b/CMakeLists.txt index 4ac4629f..6dd521e3 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -40,21 +40,17 @@ set(FSFW_FMT_LIB_VERSION v${FSFW_FMT_LIB_MAJOR_VERSION}.1.1 CACHE STRING "{fmt} library exact version requirement" ) -include(CheckIPOSupported) -check_ipo_supported(RESULT IPO_SUPPORTED OUTPUT IPO_ERROR) -if(NOT IPO_SUPPORTED) - message(STATUS "FSFW | IPO/LTO not supported: ${IPO_ERROR}") +# Keep this off by default for now. See PR: https://egit.irs.uni-stuttgart.de/fsfw/fsfw/pulls/616 +# for information which keeping this on by default is problematic +option(FSFW_ENABLE_IPO "Enable interprocedural optimization or link-time optimization if available" OFF) +if(FSFW_ENABLE_IPO) + include(CheckIPOSupported) + check_ipo_supported(RESULT IPO_SUPPORTED OUTPUT IPO_ERROR) + if(NOT IPO_SUPPORTED) + message(STATUS "FSFW | IPO/LTO not supported: ${IPO_ERROR}") + endif() endif() -option(FSFW_ENABLE_IPO "Enable interprocedural optimization or link-time optimization if available" ON) - -include(CheckIPOSupported) -check_ipo_supported(RESULT IPO_SUPPORTED OUTPUT IPO_ERROR) -if(NOT IPO_SUPPORTED) - message(STATUS "FSFW | IPO/LTO not supported: ${IPO_ERROR}") -endif() - -option(FSFW_ENABLE_IPO "Enable interprocedural optimization or link-time optimization if available" ON) option(FSFW_GENERATE_SECTIONS "Generate function and data sections. Required to remove unused code" ON )