Abdelrahman Said
55 lines
2.3 KiB
CMake
55 lines
2.3 KiB
CMake
include(CheckCSourceRuns)
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cmake_push_check_state(RESET)
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# Check whether IEEE754 doubles are laid out in little-endian order. We do this
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# only when not cross-compiling; during cross-compilation, the host architecture
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# might have different endianness conventions than the target, and we are running
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# the test on the host here
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if(CMAKE_CROSSCOMPILING AND NOT CMAKE_CROSSCOMPILING_EMULATOR)
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# If we are cross-compiling and we have no emulator, let's just assume that
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# IEEE754 doubles use the same endianness as uint64_t
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set(IEEE754_DOUBLE_ENDIANNESS_MATCHES YES)
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message(WARNING "\
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igraph is being cross-compiled, therefore we cannot validate whether the \
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endianness of IEEE754 doubles is the same as the endianness of uint64_t. \
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Most likely it is, unless you are compiling for some esoteric platform, \
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in which case you need make sure that this is the case on your own.\
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")
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else()
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if(NOT DEFINED CACHE{IEEE754_DOUBLE_ENDIANNESS_MATCHES})
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try_run(
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IEEE754_DOUBLE_ENDIANNESS_TEST_EXIT_CODE
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IEEE754_DOUBLE_ENDIANNESS_TEST_COMPILES
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${CMAKE_BINARY_DIR}
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${PROJECT_SOURCE_DIR}/etc/cmake/ieee754_endianness_check.c
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RUN_OUTPUT_VARIABLE IEEE754_DOUBLE_ENDIANNESS_TEST_RESULT
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)
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# Strip trailing newline, which is necessary on some platforms (such as node.js)
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# to complete printing the output.
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string(STRIP "${IEEE754_DOUBLE_ENDIANNESS_TEST_RESULT}" IEEE754_DOUBLE_ENDIANNESS_TEST_RESULT)
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if(IEEE754_DOUBLE_ENDIANNESS_TEST_EXIT_CODE EQUAL 0)
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if(IEEE754_DOUBLE_ENDIANNESS_TEST_RESULT STREQUAL "OK")
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set(TEST_RESULT YES)
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else()
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set(TEST_RESULT NO)
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endif()
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else()
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message(FATAL_ERROR "IEEE754 double endianness test terminated abnormally.")
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endif()
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set(
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IEEE754_DOUBLE_ENDIANNESS_MATCHES ${TEST_RESULT} CACHE BOOL
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"Specifies whether the endianness of IEEE754 doubles is the same as the endianness of uint64_t."
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FORCE
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)
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mark_as_advanced(IEEE754_DOUBLE_ENDIANNESS_MATCHES)
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endif()
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endif()
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cmake_pop_check_state()
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if(NOT IEEE754_DOUBLE_ENDIANNESS_MATCHES)
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message(FATAL_ERROR "igraph only supports platforms where IEEE754 doubles have the same endianness as uint64_t.")
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endif()
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