##
## This file is in charge of setting our paranoid flags with regard to warnings and optimization.
##
+## It is only used for gcc and clang. MSVC builds don't load this file.
+##
## These flags do break some classical CMake tests, so you don't
## want to do so before the very end of the configuration.
##
endif()
# Configure LTO
-# TODO, provide an option to manually choose whether to use LTO
# NOTE, cmake 3.0 has a INTERPROCEDURAL_OPTIMIZATION target
# property for this (http://www.cmake.org/cmake/help/v3.0/prop_tgt/INTERPROCEDURAL_OPTIMIZATION.html)
-set(enable_lto OFF)
-if(enable_compile_optimizations
- AND CMAKE_COMPILER_IS_GNUCC
- AND (NOT enable_model-checking))
- if(WIN32)
- if (COMPILER_C_VERSION_MAJOR_MINOR STRGREATER "4.8")
- # On windows, we need 4.8 or higher to enable lto because of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50293
- #
- # We are experiencing assertion failures even with 4.8 on MinGW.
- # Push the support forward: will see if 4.9 works when we test it.
+if(enable_lto) # User wants LTO. Try if we can do that
+ set(enable_lto OFF)
+ if(enable_compile_optimizations
+ AND CMAKE_COMPILER_IS_GNUCC
+ AND (NOT enable_model-checking))
+ if(WIN32)
+ if (COMPILER_C_VERSION_MAJOR_MINOR STRGREATER "4.8")
+ # On windows, we need 4.8 or higher to enable lto because of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50293
+ #
+ # We are experiencing assertion failures even with 4.8 on MinGW.
+ # Push the support forward: will see if 4.9 works when we test it.
+ set(enable_lto ON)
+ endif()
+ elseif(LINKER_VERSION STRGREATER "2.22")
set(enable_lto ON)
endif()
- elseif(LINKER_VERSION STRGREATER "2.22")
- set(enable_lto ON)
endif()
+ if(enable_lto)
+ message("-- LTO seems usable.")
+ else()
+ if(NOT enable_compile_optimizations)
+ message("-- LTO disabled: Compile-time optimizations turned off.")
+ else()
+ if(enable_model-checking)
+ message("-- LTO disabled when compiling with model-checking.")
+ else()
+ message("-- LTO does not seem usable -- try updating your build chain.")
+ endif()
+ endif()
+ endif()
+else()
+ message("-- LTO disabled on the command line.")
endif()
-if(enable_lto)
+if(enable_lto) # User wants LTO, and it seems usable. Go for it
set(optCFLAGS "${optCFLAGS} -flto ")
# See https://gcc.gnu.org/wiki/LinkTimeOptimizationFAQ#ar.2C_nm_and_ranlib:
# "Since version 4.9 gcc produces slim object files that only contain