build: MP_UNITS_DEV_TIME_TRACE CMake option added

CMakeLists.txt

@@ -24,16 +24,25 @@ cmake_minimum_required(VERSION 3.25)
 project(mp-units-dev LANGUAGES CXX)
 
 list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake")
+list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/src/cmake")
+include(CheckCacheVarValues)
 
 set(projectPrefix MP_UNITS_)
 
 option(${projectPrefix}DEV_BUILD_LA "Build code depending on the linear algebra library" OFF)
 option(${projectPrefix}DEV_IWYU "Enables include-what-you-use" OFF)
 option(${projectPrefix}DEV_CLANG_TIDY "Enables clang-tidy" OFF)
+set(${projectPrefix}DEV_TIME_TRACE
+    NONE
+    CACHE STRING
+          "Enables `-ftime-trace` for a selected scope: NONE, ALL, MODULES, HEADERS. MODULES and HEADERS do not affect unit tests."
+)
+check_cache_var_values(DEV_TIME_TRACE NONE ALL MODULES HEADERS)
 
 message(STATUS "${projectPrefix}DEV_BUILD_LA: ${${projectPrefix}DEV_BUILD_LA}")
 message(STATUS "${projectPrefix}DEV_IWYU: ${${projectPrefix}DEV_IWYU}")
 message(STATUS "${projectPrefix}DEV_CLANG_TIDY: ${${projectPrefix}DEV_CLANG_TIDY}")
+message(STATUS "${projectPrefix}DEV_TIME_TRACE: ${${projectPrefix}DEV_TIME_TRACE}")
 
 # make sure that the file is being used as an entry point
 include(modern_project_structure)
@@ -74,5 +83,4 @@ endif()
 
 # add unit tests
 enable_testing()
-
 add_subdirectory(test)

CONTRIBUTING.md

@@ -107,6 +107,20 @@ if you want to set up a development environment on your local machine.
 
     [cmake clang-tidy support]: https://github.com/mpusz/mp-units/releases/tag/v2.2.0
 
+[`MP_UNITS_DEV_TIME_TRACE`](#MP_UNITS_DEV_TIME_TRACE){ #MP_UNITS_DEV_TIME_TRACE }
+
+:   [:octicons-tag-24: 2.5.0][cmake time-trace support] · :octicons-milestone-24: `NONE`/`ALL`/`MODULES`/`HEADERS` (Default: `NONE`)
+
+    Enables compilation performance data collection with `-ftime-trace` for clang compilers.
+
+    All our unit tests compile only for headers and never for modules. To allow fair
+    comparison, `MODULES` and `HEADERS` do not enable the data collection for unit tests.
+    This means that they affect only the core, systems, and examples.
+
+    Please use `ALL` to profile unit tests as well.
+
+    [cmake time-trace support]: https://github.com/mpusz/mp-units/releases/tag/v2.5.0
+
 
 ### Building the entire repository
 

example/CMakeLists.txt

@@ -42,11 +42,17 @@ function(add_example target)
         target_compile_features(${target} PRIVATE cxx_std_20)
         target_compile_definitions(${target} PRIVATE ${projectPrefix}MODULES)
         target_link_libraries(${target} PRIVATE mp-units::mp-units ${ARGN})
+        if(${projectPrefix}DEV_TIME_TRACE STREQUAL "MODULES")
+            target_compile_options(${target} PRIVATE "-ftime-trace")
+        endif()
     endif()
 
     add_executable(${target}-headers ${target}.cpp)
     list(TRANSFORM ARGN APPEND "-headers")
     target_link_libraries(${target}-headers PRIVATE mp-units::mp-units ${ARGN})
+    if(${projectPrefix}DEV_TIME_TRACE STREQUAL "HEADERS")
+        target_compile_options(${target}-headers PRIVATE "-ftime-trace")
+    endif()
 endfunction()
 
 add_example(avg_speed)

example/glide_computer_lib/CMakeLists.txt

@@ -24,6 +24,9 @@ add_library(glide_computer_lib-headers STATIC glide_computer_lib.cpp include/gli
 target_compile_features(glide_computer_lib-headers PUBLIC cxx_std_20)
 target_link_libraries(glide_computer_lib-headers PUBLIC mp-units::mp-units example_utils-headers)
 target_include_directories(glide_computer_lib-headers PUBLIC include)
+if(${projectPrefix}DEV_TIME_TRACE STREQUAL "HEADERS")
+    target_compile_options(glide_computer_lib-headers PRIVATE "-ftime-trace")
+endif()
 
 if(${projectPrefix}BUILD_CXX_MODULES)
     add_library(glide_computer_lib STATIC glide_computer_lib.cpp include/glide_computer_lib.h)
@@ -31,4 +34,8 @@ if(${projectPrefix}BUILD_CXX_MODULES)
     target_compile_definitions(glide_computer_lib PUBLIC ${projectPrefix}MODULES)
     target_link_libraries(glide_computer_lib PUBLIC mp-units::mp-units example_utils)
     target_include_directories(glide_computer_lib PUBLIC include)
+
+    if(${projectPrefix}DEV_TIME_TRACE STREQUAL "MODULES")
+        target_compile_options(glide_computer_lib PRIVATE "-ftime-trace")
+    endif()
 endif()

src/core/CMakeLists.txt

@@ -151,3 +151,9 @@ target_compile_definitions(
     mp-units-core ${${projectPrefix}TARGET_SCOPE}
                   ${projectPrefix}HOSTED=$<NOT:$<BOOL:${${projectPrefix}API_FREESTANDING}>>
 )
+
+if(${projectPrefix}DEV_TIME_TRACE STREQUAL "ALL")
+    target_compile_options(mp-units-core ${${projectPrefix}TARGET_SCOPE} "-ftime-trace")
+elseif(${projectPrefix}DEV_TIME_TRACE STREQUAL "MODULES")
+    target_compile_options(mp-units-core PRIVATE "-ftime-trace")
+endif()

src/systems/CMakeLists.txt

@@ -71,3 +71,7 @@ if(NOT ${projectPrefix}API_FREESTANDING)
                include/mp-units/systems/si/chrono.h
     )
 endif()
+
+if(${projectPrefix}DEV_TIME_TRACE STREQUAL "MODULES")
+    target_compile_options(mp-units-systems PRIVATE "-ftime-trace")
+endif()