forked from OSchip/llvm-project
100 lines
3.7 KiB
CMake
100 lines
3.7 KiB
CMake
#------------------------------------------------------------------------------
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# Cpu features definition and flags
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#
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# Declare a list of all supported cpu features in ALL_CPU_FEATURES.
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#
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# Declares associated flags to enable/disable individual feature of the form:
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# - CPU_FEATURE_<FEATURE>_ENABLE_FLAG
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# - CPU_FEATURE_<FEATURE>_DISABLE_FLAG
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#
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#------------------------------------------------------------------------------
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if(${LIBC_TARGET_MACHINE} MATCHES "x86|x86_64")
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set(ALL_CPU_FEATURES SSE SSE2 AVX AVX512F)
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endif()
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function(_define_cpu_feature_flags feature)
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if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
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string(TOLOWER ${feature} lowercase_feature)
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set(CPU_FEATURE_${feature}_ENABLE_FLAG "-m${lowercase_feature}" PARENT_SCOPE)
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set(CPU_FEATURE_${feature}_DISABLE_FLAG "-mno-${lowercase_feature}" PARENT_SCOPE)
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else()
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# In future, we can extend for other compilers.
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message(FATAL_ERROR "Unkown compiler ${CMAKE_CXX_COMPILER_ID}.")
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endif()
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endfunction()
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# Defines cpu features flags
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foreach(feature IN LISTS ALL_CPU_FEATURES)
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_define_cpu_feature_flags(${feature})
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endforeach()
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#------------------------------------------------------------------------------
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# Optimization level flags
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#
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# Generates the set of flags needed to compile for a up to a particular
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# optimization level.
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#
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# Creates variables of the form `CPU_FEATURE_OPT_<FEATURE>_FLAGS`.
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# CPU_FEATURE_OPT_NONE_FLAGS is a special flag for which no feature is needed.
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#
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# e.g.
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# CPU_FEATURE_OPT_NONE_FLAGS : -mno-sse;-mno-sse2;-mno-avx;-mno-avx512f
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# CPU_FEATURE_OPT_SSE_FLAGS : -msse;-mno-sse2;-mno-avx;-mno-avx512f
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# CPU_FEATURE_OPT_SSE2_FLAGS : -msse;-msse2;-mno-avx;-mno-avx512f
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# CPU_FEATURE_OPT_AVX_FLAGS : -msse;-msse2;-mavx;-mno-avx512f
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# CPU_FEATURE_OPT_AVX512F_FLAGS : -msse;-msse2;-mavx;-mavx512f
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#------------------------------------------------------------------------------
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# Helper function to concatenate flags needed to support optimization up to
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# a particular feature.
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function(_generate_flags_for_up_to feature flag_variable)
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list(FIND ALL_CPU_FEATURES ${feature} feature_index)
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foreach(current_feature IN LISTS ALL_CPU_FEATURES)
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list(FIND ALL_CPU_FEATURES ${current_feature} current_feature_index)
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if(${current_feature_index} GREATER ${feature_index})
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list(APPEND flags ${CPU_FEATURE_${current_feature}_DISABLE_FLAG})
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else()
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list(APPEND flags ${CPU_FEATURE_${current_feature}_ENABLE_FLAG})
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endif()
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endforeach()
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set(${flag_variable} ${flags} PARENT_SCOPE)
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endfunction()
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function(_generate_opt_levels)
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set(opt_levels NONE)
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list(APPEND opt_levels ${ALL_CPU_FEATURES})
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foreach(feature IN LISTS opt_levels)
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set(flag_name "CPU_FEATURE_OPT_${feature}_FLAGS")
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_generate_flags_for_up_to(${feature} ${flag_name})
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set(${flag_name} ${${flag_name}} PARENT_SCOPE)
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endforeach()
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endfunction()
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_generate_opt_levels()
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#------------------------------------------------------------------------------
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# Host cpu feature introspection
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#
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# Populates a HOST_CPU_FEATURES list containing the available CPU_FEATURE.
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#------------------------------------------------------------------------------
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function(_check_host_cpu_feature feature)
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string(TOLOWER ${feature} lowercase_feature)
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try_run(
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run_result
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compile_result
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"${CMAKE_CURRENT_BINARY_DIR}/check_${lowercase_feature}"
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"${CMAKE_MODULE_PATH}/cpu_features/check_${lowercase_feature}.cpp"
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COMPILE_DEFINITIONS ${CPU_FEATURE_${feature}_ENABLE_FLAG}
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OUTPUT_VARIABLE compile_output
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)
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if(${compile_result} AND ("${run_result}" EQUAL 0))
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list(APPEND HOST_CPU_FEATURES ${feature})
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set(HOST_CPU_FEATURES ${HOST_CPU_FEATURES} PARENT_SCOPE)
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endif()
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endfunction()
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foreach(feature IN LISTS ALL_CPU_FEATURES)
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_check_host_cpu_feature(${feature})
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endforeach()
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