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activate LTO on platforms that support it, ie. most recent compilers

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This commit is contained in:
Dennis Luxen 2014-04-01 17:54:41 +02:00
parent 05c33bee78
commit d21f63d327
2 changed files with 44 additions and 0 deletions
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15
CMakeLists.txt
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@ -1,6 +1,7 @@
cmake_minimum_required(VERSION 2.6) cmake_minimum_required(VERSION 2.6)
project(OSRM) project(OSRM)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON) set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
include(CheckCXXCompilerFlag)
include(FindPackageHandleStandardArgs) include(FindPackageHandleStandardArgs)
list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake") list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake")
@ -103,6 +104,20 @@ elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
# using Visual Studio C++ # using Visual Studio C++
endif() endif()
# Check if LTO is available
set(LTO_FLAGS "")
CHECK_CXX_COMPILER_FLAG("-flto" HAS_LTO_FLAG)
if (HAS_LTO_FLAG)
set(LTO_FLAGS "${LTO_FLAGS} -flto")
else (HAS_LTO_FLAG)
set(LTO_FLAGS "${LTO_FLAGS} -flto")
endif (HAS_LTO_FLAG)
# Add Link-Time-Optimization flags, if supported (GCC >= 4.5) and enabled
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LTO_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${LTO_FLAGS}")
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${LTO_FLAGS}")
# Configuring other platform dependencies # Configuring other platform dependencies
if(APPLE) if(APPLE)
set(CMAKE_OSX_ARCHITECTURES "x86_64") set(CMAKE_OSX_ARCHITECTURES "x86_64")

29
cmake/CheckCXXCompilerFlag.cmake Normal file
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@ -0,0 +1,29 @@
# - Check whether the CXX compiler supports a given flag.
# CHECK_CXX_COMPILER_FLAG(<flag> <var>)
# <flag> - the compiler flag
# <var> - variable to store the result
# This internally calls the check_cxx_source_compiles macro. See help
# for CheckCXXSourceCompiles for a listing of variables that can
# modify the build.
# Copyright (c) 2006, Alexander Neundorf, <neundorf@kde.org>
#
# Redistribution and use is allowed according to the terms of the BSD license.
# For details see the accompanying COPYING-CMAKE-SCRIPTS file.
INCLUDE(CheckCXXSourceCompiles)
MACRO (CHECK_CXX_COMPILER_FLAG _FLAG _RESULT)
SET(SAFE_CMAKE_REQUIRED_DEFINITIONS "${CMAKE_REQUIRED_DEFINITIONS}")
SET(CMAKE_REQUIRED_DEFINITIONS "${_FLAG}")
CHECK_CXX_SOURCE_COMPILES("int main() { return 0;}" ${_RESULT}
# Some compilers do not fail with a bad flag
FAIL_REGEX "unrecognized .*option" # GNU
FAIL_REGEX "ignoring unknown option" # MSVC
FAIL_REGEX "[Uu]nknown option" # HP
FAIL_REGEX "[Ww]arning: [Oo]ption" # SunPro
FAIL_REGEX "command option .* is not recognized" # XL
)
SET (CMAKE_REQUIRED_DEFINITIONS "${SAFE_CMAKE_REQUIRED_DEFINITIONS}")
ENDMACRO (CHECK_CXX_COMPILER_FLAG)