From 0fe1b70baedfe250d5d39be3e5545bab3806a9f0 Mon Sep 17 00:00:00 2001 From: Robin Mueller Date: Tue, 10 May 2022 11:19:29 +0200 Subject: [PATCH] keep LTO option off by default --- CHANGELOG.md | 10 ++++++++++ CMakeLists.txt | 17 +++++++++-------- 2 files changed, 19 insertions(+), 8 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index 0452e58b..f3523a73 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 9f686d1d..61145e1e 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -17,11 +17,12 @@ set(FSFW_REVISION 0) # Add the cmake folder so the FindSphinx module is found set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake" ${CMAKE_MODULE_PATH}) +set(FSFW_ETL_LIB_NAME etl) set(FSFW_ETL_LIB_MAJOR_VERSION 20 CACHE STRING - "ETL library major version requirement" + "ETL library major version requirement" ) set(FSFW_ETL_LIB_VERSION ${FSFW_ETL_LIB_MAJOR_VERSION}.27.3 CACHE STRING - "ETL library exact version requirement" + "ETL library exact version requirement" ) set(FSFW_ETL_LINK_TARGET etl::etl) @@ -32,26 +33,26 @@ set(FSFW_CATCH2_LIB_VERSION v${FSFW_CATCH2_LIB_MAJOR_VERSION}.0.0-preview5 CACHE "Catch2 library exact version requirement" ) -set(FSFW_ETL_LIB_NAME etl) - 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) +# 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) option(FSFW_GENERATE_SECTIONS - "Generate function and data sections. Required to remove unused code" ON + "Generate function and data sections. Required to remove unused code" ON ) if(FSFW_GENERATE_SECTIONS) - option(FSFW_REMOVE_UNUSED_CODE "Remove unused code" ON) + option(FSFW_REMOVE_UNUSED_CODE "Remove unused code" ON) endif() option(FSFW_BUILD_UNITTESTS "Build unittest binary in addition to static library" OFF) option(FSFW_BUILD_DOCS "Build documentation with Sphinx and Doxygen" OFF) if(FSFW_BUILD_UNITTESTS) - option(FSFW_TESTS_GEN_COV "Generate coverage data for unittests" ON) + option(FSFW_TESTS_GEN_COV "Generate coverage data for unittests" ON) endif() option(FSFW_WARNING_SHADOW_LOCAL_GCC "Enable -Wshadow=local warning in GCC" ON)