CMake/Modules/Compiler/GNU.cmake
Brad King ba247ccaba IPO: Consider support for each language separately
We only define `INTERPROCEDURAL_OPTIMIZATION` behavior for C, CXX, and
Fortran languages.  Do not try to enable support for other languages.
Furthermore, each language builds with a different compiler, so check
for support by CMake and the compiler for each language independently.

Fixes: #16944
2017-06-14 10:36:57 -04:00

90 lines
3.7 KiB
CMake

# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
# This module is shared by multiple languages; use include blocker.
if(__COMPILER_GNU)
return()
endif()
set(__COMPILER_GNU 1)
include(Compiler/CMakeCommonCompilerMacros)
macro(__compiler_gnu lang)
# Feature flags.
set(CMAKE_${lang}_VERBOSE_FLAG "-v")
set(CMAKE_${lang}_COMPILE_OPTIONS_PIC "-fPIC")
if(NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 3.4)
set(CMAKE_${lang}_COMPILE_OPTIONS_PIE "-fPIE")
endif()
if(NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 4.0)
set(CMAKE_${lang}_COMPILE_OPTIONS_VISIBILITY "-fvisibility=")
endif()
set(CMAKE_SHARED_LIBRARY_${lang}_FLAGS "-fPIC")
set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-shared")
set(CMAKE_${lang}_COMPILE_OPTIONS_SYSROOT "--sysroot=")
# Older versions of gcc (< 4.5) contain a bug causing them to report a missing
# header file as a warning if depfiles are enabled, causing check_header_file
# tests to always succeed. Work around this by disabling dependency tracking
# in try_compile mode.
get_property(_IN_TC GLOBAL PROPERTY IN_TRY_COMPILE)
if(NOT _IN_TC OR CMAKE_FORCE_DEPFILES)
# distcc does not transform -o to -MT when invoking the preprocessor
# internally, as it ought to. Work around this bug by setting -MT here
# even though it isn't strictly necessary.
set(CMAKE_DEPFILE_FLAGS_${lang} "-MD -MT <OBJECT> -MF <DEPFILE>")
endif()
# Initial configuration flags.
string(APPEND CMAKE_${lang}_FLAGS_INIT " ")
string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -g")
string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -Os -DNDEBUG")
string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O3 -DNDEBUG")
string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O2 -g -DNDEBUG")
set(CMAKE_${lang}_CREATE_PREPROCESSED_SOURCE "<CMAKE_${lang}_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -E <SOURCE> > <PREPROCESSED_SOURCE>")
set(CMAKE_${lang}_CREATE_ASSEMBLY_SOURCE "<CMAKE_${lang}_COMPILER> <DEFINES> <INCLUDES> <FLAGS> -S <SOURCE> -o <ASSEMBLY_SOURCE>")
if(NOT APPLE OR NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 4) # work around #4462
set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-isystem ")
endif()
set(_CMAKE_${lang}_IPO_SUPPORTED_BY_CMAKE YES)
set(_CMAKE_${lang}_IPO_MAY_BE_SUPPORTED_BY_COMPILER NO)
# '-flto' introduced since GCC 4.5:
# * https://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Option-Summary.html (no)
# * https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc/Option-Summary.html (yes)
if(NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 4.5)
set(_CMAKE_${lang}_IPO_MAY_BE_SUPPORTED_BY_COMPILER YES)
set(__lto_flags -flto)
if(NOT CMAKE_${lang}_COMPILER_VERSION VERSION_LESS 4.7)
# '-ffat-lto-objects' introduced since GCC 4.7:
# * https://gcc.gnu.org/onlinedocs/gcc-4.6.4/gcc/Option-Summary.html (no)
# * https://gcc.gnu.org/onlinedocs/gcc-4.7.4/gcc/Option-Summary.html (yes)
list(APPEND __lto_flags -fno-fat-lto-objects)
endif()
set(CMAKE_${lang}_COMPILE_OPTIONS_IPO ${__lto_flags})
# Need to use version of 'ar'/'ranlib' with plugin support.
# Quote from [documentation][1]:
#
# To create static libraries suitable for LTO,
# use gcc-ar and gcc-ranlib instead of ar and ranlib
#
# [1]: https://gcc.gnu.org/onlinedocs/gcc-4.9.4/gcc/Optimize-Options.html
set(CMAKE_${lang}_ARCHIVE_CREATE_IPO
"${CMAKE_${lang}_COMPILER_AR} cr <TARGET> <LINK_FLAGS> <OBJECTS>"
)
set(CMAKE_${lang}_ARCHIVE_APPEND_IPO
"${CMAKE_${lang}_COMPILER_AR} r <TARGET> <LINK_FLAGS> <OBJECTS>"
)
set(CMAKE_${lang}_ARCHIVE_FINISH_IPO
"${CMAKE_${lang}_COMPILER_RANLIB} <TARGET>"
)
endif()
endmacro()