[INFRA] Better LTO handling

Force projects that include HIBF to enable CMAKE_INTERPROCEDURAL_OPTIMIZATION.
CMake does not only detect the compiler flags, but also chooses
programs that support the lto-plugin (ar, ranlib, ...).
This means that exporting the CXX_FLAGS is not enough, because linking
might fail due to the wrong programs being chosen.

cmake/configuration.cmake

@@ -231,8 +231,7 @@ else ()
 endif ()
 
 check_cxx_compiler_flag ("-march=native" HIBF_HAS_MARCH_NATIVE)
-cmake_dependent_option (HIBF_NATIVE_BUILD "Optimize build for current architecture." ON
-                        "HIBF_HAS_MARCH_NATIVE;NOT HIBF_IS_DEBUG" OFF)
+cmake_dependent_option (HIBF_NATIVE_BUILD "Optimize build for current architecture." ON "HIBF_HAS_MARCH_NATIVE" OFF)
 
 if (HIBF_NATIVE_BUILD)
     list (APPEND HIBF_CXX_FLAGS "-march=native")
@@ -248,21 +247,31 @@ else ()
 endif ()
 
 check_ipo_supported (RESULT HIBF_HAS_LTO OUTPUT HIBF_HAS_LTO_OUTPUT)
-cmake_dependent_option (HIBF_LTO_BUILD "Use Link Time Optimisation." ON "HIBF_HAS_LTO;NOT HIBF_IS_DEBUG" OFF)
-
-if (HIBF_LTO_BUILD)
+cmake_dependent_option (HIBF_LTO_BUILD "Use Link Time Optimisation." ON "HIBF_HAS_LTO" OFF)
+cmake_dependent_option (HIBF_DEV_CHECK_LTO "LTO check." ON
+                        "HIBF_LTO_BUILD;NOT HIBF_IS_TOP_LEVEL;NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION" OFF)
+
+if (HIBF_DEV_CHECK_LTO)
+    message (FATAL_ERROR " HIBF heavily benefits from Link Time Optimisation (LTO).\n"
+                         " Your compiler supports LTO, but is has not been enabled for your project.\n \n"
+                         " Add the following at the beginning of your CMakeLists.txt:\n"
+                         " ```\n"
+                         " include (CheckIPOSupported)\n"
+                         " check_ipo_supported (RESULT result OUTPUT output)\n"
+                         " if (result)\n"
+                         "     set (CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)\n"
+                         " endif ()\n"
+                         " ```"
+                         " \n \n"
+                         " For development purposes, this error can be disabled via `HIBF_DEV_CHECK_LTO=OFF`.")
+elseif (HIBF_LTO_BUILD)
     set (CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
-    list (APPEND HIBF_CXX_FLAGS ${CMAKE_CXX_COMPILE_OPTIONS_IPO})
     hibf_config_print ("Link Time Optimisation:     enabled")
 else ()
-    if (HIBF_IS_DEBUG)
-        hibf_config_print ("Link Time Optimisation:     disabled")
-    else ()
-        set (HIBF_LTO_LOG "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/hibf.lto.log")
-        file (WRITE "${HIBF_LTO_LOG}" "${HIBF_HAS_LTO_OUTPUT}")
-        hibf_config_print ("Link Time Optimisation:     not supported")
-        hibf_config_print ("  See ${HIBF_LTO_LOG}")
-    endif ()
+    set (HIBF_LTO_LOG "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/hibf.lto.log")
+    file (WRITE "${HIBF_LTO_LOG}" "${HIBF_HAS_LTO_OUTPUT}")
+    hibf_config_print ("Link Time Optimisation:     not supported")
+    hibf_config_print ("  See ${HIBF_LTO_LOG}")
 endif ()
 
 # ----------------------------------------------------------------------------

cmake/hibf-config.cmake.in

@@ -4,6 +4,8 @@
 
 @PACKAGE_INIT@
 
+include (CheckIPOSupported)
+include (CMakeDependentOption)
 include (CMakeFindDependencyMacro)
 
 find_dependency (cereal @HIBF_CEREAL_VERSION@ REQUIRED)
@@ -26,4 +28,22 @@ else ()
     find_dependency (simde @HIBF_SIMDE_VERSION@ REQUIRED)
 endif ()
 
+check_ipo_supported (RESULT HIBF_HAS_LTO OUTPUT HIBF_HAS_LTO_OUTPUT)
+cmake_dependent_option (HIBF_DEV_CHECK_LTO "LTO check." ON "HIBF_HAS_LTO;NOT CMAKE_INTERPROCEDURAL_OPTIMIZATION" OFF)
+
+if (HIBF_DEV_CHECK_LTO)
+    message (FATAL_ERROR " HIBF heavily benefits from Link Time Optimisation (LTO).\n"
+                         " Your compiler supports LTO, but is has not been enabled for your project.\n \n"
+                         " Add the following at the beginning of your CMakeLists.txt:\n"
+                         " ```\n"
+                         " include (CheckIPOSupported)\n"
+                         " check_ipo_supported (RESULT result OUTPUT output)\n"
+                         " if (result)\n"
+                         "     set (CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)\n"
+                         " endif ()\n"
+                         " ```"
+                         " \n \n"
+                         " For development purposes, this error can be disabled via `HIBF_DEV_CHECK_LTO=OFF`.")
+endif ()
+
 include ("${CMAKE_CURRENT_LIST_DIR}/hibf-targets.cmake")

cmake/package-lock.cmake

@@ -19,7 +19,8 @@ CPMDeclarePackage (simde
                    NAME simde
                    VERSION ${HIBF_SIMDE_VERSION}
                    GITHUB_REPOSITORY simd-everywhere/simde
-                   DOWNLOAD_ONLY YES)
+                   DOWNLOAD_ONLY YES #
+                   QUIET YES)
 # benchmark
 set (HIBF_BENCHMARK_VERSION 1.9.0)
 CPMDeclarePackage (benchmark

test/hibf-test.cmake

@@ -13,6 +13,12 @@ cmake_minimum_required (VERSION 3.10...3.30)
 # have to be adapted or the option deactivated.
 option (HIBF_BENCHMARK_ALIGN_LOOPS "Pass -falign-loops=32 to the benchmark builds." ON)
 
+include (CheckIPOSupported)
+check_ipo_supported (RESULT HIBF_TEST_HAS_LTO OUTPUT HIBF_TEST_HAS_LTO_OUTPUT)
+if (HIBF_TEST_HAS_LTO)
+    set (CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
+endif ()
+
 get_filename_component (HIBF_ROOT_DIR "${CMAKE_CURRENT_LIST_DIR}/.." ABSOLUTE)
 add_subdirectory ("${HIBF_ROOT_DIR}" "${CMAKE_CURRENT_BINARY_DIR}/hibf_lib")
 target_compile_options (hibf PUBLIC "-pedantic" "-Wall" "-Wextra" "-Werror")

util/CMakeLists.txt

@@ -5,9 +5,10 @@
 cmake_minimum_required (VERSION 3.10...3.30)
 project (hibf_util CXX)
 
-# https://cmake.org/cmake/help/latest/policy/CMP0135.html
-if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.24)
-    cmake_policy (SET CMP0135 NEW)
+include (CheckIPOSupported)
+check_ipo_supported (RESULT HIBF_TEST_HAS_LTO OUTPUT HIBF_TEST_HAS_LTO_OUTPUT)
+if (HIBF_TEST_HAS_LTO)
+    set (CMAKE_INTERPROCEDURAL_OPTIMIZATION TRUE)
 endif ()
 
 # Dependency: seqan::hibf