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CMake: Enable LTCG/LTO

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Nicolas Hake 2016-03-31 21:23:25 +02:00
parent d3d41721f0
commit 0c6fee1442
1 changed files with 64 additions and 0 deletions
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64
CMakeLists.txt
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@ -55,6 +55,65 @@ if(USE_GCC_STD_14)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=gnu++14")
endif()
# Enable link-time code generation. We have to do this manually because while
# there is a INTERPROCEDURAL_OPTIMIZATION cmake flag, it's only implemented
# for icc so far; https://cmake.org/Bug/view.php?id=15939
function(add_linker_flags)
include(CMakeParseArguments)
set(options optimized debug)
set(oneValueArgs FLAGS)
set(multiValueArgs MODULES)
cmake_parse_arguments(_alf "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
# Adds some linker flags to all optimized build configurations
set(_configurations "")
if(_alf_optimized)
list(APPEND _configurations MINSIZEREL RELWITHDEBINFO RELEASE)
endif()
if(_alf_debug)
list(APPEND _configurations DEBUG)
endif()
foreach(_module ${_alf_MODULES})
string(TOUPPER "${_module}" _obj_type)
foreach(_config ${_configurations})
set(CMAKE_${_obj_type}_LINKER_FLAGS_${_config} "${CMAKE_${_obj_type}_LINKER_FLAGS_${_config}} ${_alf_FLAGS}" PARENT_SCOPE)
endforeach()
endforeach()
endfunction()
CHECK_CXX_COMPILER_FLAG("-flto" USE_GCC_STYLE_LTCG)
if(USE_GCC_STYLE_LTCG)
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -flto")
set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_CXX_FLAGS_MINSIZEREL} -flto")
add_linker_flags(optimized MODULES exe shared FLAGS -flto)
# Use GCC's ar and ranlib wrappers if necessary, because the plain ones
# don't understand lto objects without an explicit plugin parameter
if(CMAKE_C_COMPILER MATCHES "gcc$")
set(LTCG_NEEDS_AR_WRAPPER 1)
set(LTCG_AR_WRAPPER_PREFIX "${CMAKE_C_COMPILER}")
elseif(CMAKE_C_COMPILER MATCHES "cc$")
set(LTCG_NEEDS_AR_WRAPPER 1)
set(LTCG_AR_WRAPPER_PREFIX "gcc")
else()
set(LTCG_NEEDS_AR_WRAPPER 0)
endif()
if(LTCG_NEEDS_AR_WRAPPER)
find_program(AR_WRAPPER "${LTCG_AR_WRAPPER_PREFIX}-ar")
if (AR_WRAPPER)
message("Using ${AR_WRAPPER} instead of ${CMAKE_AR} to support lto objects.")
set(CMAKE_AR "${AR_WRAPPER}" CACHE FILEPATH "Path to an ar that supports lto objects." FORCE)
endif()
find_program(RANLIB_WRAPPER "${LTCG_AR_WRAPPER_PREFIX}-ranlib")
if (RANLIB_WRAPPER)
message("Using ${RANLIB_WRAPPER} instead of ${CMAKE_RANLIB} to support lto objects.")
set(CMAKE_RANLIB "${RANLIB_WRAPPER}" CACHE FILEPATH "Path to a ranlib that supports lto objects." FORCE)
endif()
endif()
endif()
if(MSVC)
# Disable non-standard conversion from string literal to (nonconst) char*
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zc:strictStrings")
@ -62,6 +121,11 @@ if(MSVC)
# Enable multi-core builds
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /MP")
# Enable LTCG for release builds
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} /Ob2 /GL")
set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_CXX_FLAGS_MINSIZEREL} /Ob2 /GL")
add_linker_flags(optimized MODULES exe shared static FLAGS /LTCG)
# Activate edit-and-continue
set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS} /ZI /Gy")