forked from OSchip/llvm-project
57 lines
2.5 KiB
CMake
57 lines
2.5 KiB
CMake
# This function defines a linker script in place of the symlink traditionally
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# created for shared libraries.
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#
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# More specifically, this function goes through the PUBLIC and INTERFACE
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# library dependencies of <target> and gathers them into a linker script,
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# such that those libraries are linked against when the shared library for
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# <target> is linked against.
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#
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# Arguments:
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# <target>: A target representing a shared library. A linker script will be
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# created in place of that target's TARGET_LINKER_FILE, which is
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# the symlink pointing to the actual shared library (usually
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# libFoo.so pointing to libFoo.so.1, which itself points to
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# libFoo.so.1.0).
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function(define_linker_script target)
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if (NOT TARGET "${target}")
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message(FATAL_ERROR "The provided target '${target}' is not actually a target.")
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endif()
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get_target_property(target_type "${target}" TYPE)
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if (NOT "${target_type}" STREQUAL "SHARED_LIBRARY")
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message(FATAL_ERROR "The provided target '${target}' is not a shared library (its type is '${target_type}').")
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endif()
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set(symlink "$<TARGET_LINKER_FILE:${target}>")
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set(soname "$<TARGET_SONAME_FILE_NAME:${target}>")
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get_target_property(interface_libs "${target}" INTERFACE_LINK_LIBRARIES)
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set(link_libraries)
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if (interface_libs)
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foreach(lib IN LISTS interface_libs)
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if ("${lib}" STREQUAL "cxx-headers")
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continue()
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endif()
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# If ${lib} is not a target, we use a dummy target which we know will
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# have an OUTPUT_NAME property so that CMake doesn't fail when evaluating
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# the non-selected branch of the `IF`. It doesn't matter what it evaluates
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# to because it's not selected, but it must not cause an error.
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# See https://gitlab.kitware.com/cmake/cmake/-/issues/21045.
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set(output_name_tgt "$<IF:$<TARGET_EXISTS:${lib}>,${lib},${target}>")
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set(libname "$<IF:$<TARGET_EXISTS:${lib}>,$<TARGET_PROPERTY:${output_name_tgt},OUTPUT_NAME>,${lib}>")
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list(APPEND link_libraries "${CMAKE_LINK_LIBRARY_FLAG}${libname}")
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endforeach()
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endif()
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string(REPLACE ";" " " link_libraries "${link_libraries}")
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set(linker_script "INPUT(${soname} ${link_libraries})")
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add_custom_command(TARGET "${target}" POST_BUILD
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COMMAND "${CMAKE_COMMAND}" -E remove "${symlink}"
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COMMAND "${CMAKE_COMMAND}" -E echo "${linker_script}" > "${symlink}"
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COMMENT "Generating linker script: '${linker_script}' as file ${symlink}"
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VERBATIM
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)
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endfunction()
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