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https://github.com/Z3Prover/z3
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0e1343e78d
This analogous to the `--optimize` flag in the Python/Makefile build system except that we now support doing LTO with Clang/GCC as well. However it is probably best to avoid doing LTO with Clang or GCC for now because I see a bunch of warnings about ODR violations when building with LTO. LTO can be enabled with the new `LINK_TIME_OPTIMIZATION` option which is off by default.
52 lines
2.3 KiB
CMake
52 lines
2.3 KiB
CMake
option(LINK_TIME_OPTIMIZATION "Use link time optimiziation" OFF)
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if (LINK_TIME_OPTIMIZATION)
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message(STATUS "LTO enabled")
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set(build_types_with_lto "RELEASE" "RELWITHDEBINFO")
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if (DEFINED CMAKE_CONFIGURATION_TYPES)
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# Multi configuration generator
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message(STATUS "Note LTO is only enabled for the following configurations: ${build_types_with_lto}")
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else()
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# Single configuration generator
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string(TOUPPER "${CMAKE_BUILD_TYPE}" _build_type_upper)
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list(FIND build_types_with_lto "${_build_type_upper}" _index)
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if ("${_index}" EQUAL -1)
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message(FATAL_ERROR "Configuration ${CMAKE_BUILD_TYPE} does not support LTO."
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"You should set LINK_TIME_OPTIMIZATION to OFF.")
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endif()
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endif()
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set(_lto_compiler_flag "")
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set(_lto_linker_flag "")
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if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR
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("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU"))
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set(_lto_compiler_flag "-flto")
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set(_lto_linker_flag "-flto")
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# FIXME: Remove "x.." when CMP0054 is set to NEW
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elseif ("x${CMAKE_CXX_COMPILER_ID}" STREQUAL "xMSVC")
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set(_lto_compiler_flag "/GL")
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set(_lto_linker_flag "/LTCG")
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else()
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message(FATAL_ERROR "Can't enable LTO for compiler \"${CMAKE_CXX_COMPILER_ID}\"."
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"You should set LINK_TIME_OPTIMIZATION to OFF.")
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endif()
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CHECK_CXX_COMPILER_FLAG("${_lto_compiler_flag}" HAS_LTO)
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if (NOT HAS_LTO)
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message(FATAL_ERROR "Compiler does not support LTO")
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endif()
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foreach (_config ${build_types_with_lto})
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# Set flags compiler and linker flags globally rather than using
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# `Z3_COMPONENT_CXX_FLAGS` and `Z3_DEPENDENT_EXTRA_CXX_LINK_FLAGS`
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# respectively. We need per configuration compiler and linker flags. The
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# `LINK_FLAGS` property (which we populate with
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# `Z3_DEPENDENT_EXTRA_CXX_LINK_FLAGS`) doesn't seem to support generator
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# expressions so we can't do `$<$<CONFIG:Release>:${_lto_linker_flag}>`.
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set(CMAKE_CXX_FLAGS_${_config} "${CMAKE_CXX_FLAGS_${_config}} ${_lto_compiler_flag}")
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set(CMAKE_EXE_LINKER_FLAGS_${_config} "${CMAKE_EXE_LINKER_FLAGS_${_config}} ${_lto_linker_flag}")
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set(CMAKE_SHARED_LINKER_FLAGS_${_config} "${CMAKE_SHARED_LINKER_FLAGS_${_config}} ${_lto_linker_flag}")
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set(CMAKE_STATIC_LINKER_FLAGS_${_config} "${CMAKE_STATIC_LINKER_FLAGS_${_config}} ${_lto_linker_flag}")
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endforeach()
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else()
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message(STATUS "LTO disabled")
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endif()
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