forked from OSchip/llvm-project
[libc] Simplifies multi implementations
This is a roll forward of D101895 with two additional fixes: Original Patch description: > This is a follow up on D101524 which: > > - simplifies cpu features detection and usage, > - flattens target dependent optimizations so it's obvious which implementations are generated, > - provides an implementation targeting the host (march/mtune=native) for the mem* functions, > - makes sure all implementations are unittested (provided the host can run them). Additional fixes: - Fix uninitialized ALL_CPU_FEATURES - Use non pseudo microarch as it is only supported from Clang 12 on Differential Revision: https://reviews.llvm.org/D102233
This commit is contained in:
Guillaume Chatelet
parent
8aa7f28497
commit
6351993da7
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@ -2,11 +2,19 @@
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# Cpu features definition and flags
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# ------------------------------------------------------------------------------
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# Initialize ALL_CPU_FEATURES as empty list.
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set(ALL_CPU_FEATURES "")
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if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
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set(ALL_CPU_FEATURES SSE SSE2 AVX AVX2 AVX512F)
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list(SORT ALL_CPU_FEATURES)
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set(ALL_CPU_FEATURES SSE2 SSE4_2 AVX2 AVX512F)
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set(LIBC_COMPILE_OPTIONS_NATIVE -march=native)
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elseif(${LIBC_TARGET_ARCHITECTURE_IS_AARCH64})
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set(LIBC_COMPILE_OPTIONS_NATIVE -mcpu=native)
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endif()
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# Making sure ALL_CPU_FEATURES is sorted.
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list(SORT ALL_CPU_FEATURES)
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# Function to check whether the target CPU supports the provided set of features.
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# Usage:
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# cpu_supports(
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@ -22,49 +30,6 @@ function(cpu_supports output_var features)
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endif()
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endfunction()
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# Function to compute the flags to pass down to the compiler.
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# Usage:
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# compute_flags(
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# <output variable>
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# MARCH <arch name or "native">
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# REQUIRE <list of mandatory features to enable>
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# REJECT <list of features to disable>
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# )
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function(compute_flags output_var)
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cmake_parse_arguments(
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"COMPUTE_FLAGS"
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"" # Optional arguments
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"MARCH" # Single value arguments
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"REQUIRE;REJECT" # Multi value arguments
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${ARGN})
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# Check that features are not required and rejected at the same time.
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if(COMPUTE_FLAGS_REQUIRE AND COMPUTE_FLAGS_REJECT)
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_intersection(var ${COMPUTE_FLAGS_REQUIRE} ${COMPUTE_FLAGS_REJECT})
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if(var)
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message(FATAL_ERROR "Cpu Features REQUIRE and REJECT ${var}")
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endif()
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endif()
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# Generate the compiler flags in `current`.
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if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang|GNU")
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if(COMPUTE_FLAGS_MARCH)
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list(APPEND current "-march=${COMPUTE_FLAGS_MARCH}")
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endif()
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foreach(feature IN LISTS COMPUTE_FLAGS_REQUIRE)
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string(TOLOWER ${feature} lowercase_feature)
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list(APPEND current "-m${lowercase_feature}")
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endforeach()
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foreach(feature IN LISTS COMPUTE_FLAGS_REJECT)
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string(TOLOWER ${feature} lowercase_feature)
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list(APPEND current "-mno-${lowercase_feature}")
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endforeach()
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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 ${CMAKE_CXX_COMPILER_ID}.")
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endif()
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# Export the list of flags.
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set(${output_var} "${current}" PARENT_SCOPE)
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endfunction()
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# ------------------------------------------------------------------------------
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# Internal helpers and utilities.
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# ------------------------------------------------------------------------------
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@ -94,39 +59,7 @@ function(_generate_check_code)
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endfunction()
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_generate_check_code()
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# Compiles and runs the code generated above with the specified requirements.
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# This is helpful to infer which features a particular target supports or if
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# a specific features implies other features (e.g. BMI2 implies SSE2 and SSE).
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function(_check_defined_cpu_feature output_var)
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cmake_parse_arguments(
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"CHECK_DEFINED"
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"" # Optional arguments
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"MARCH" # Single value arguments
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"REQUIRE;REJECT" # Multi value arguments
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${ARGN})
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compute_flags(
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flags
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MARCH ${CHECK_DEFINED_MARCH}
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REQUIRE ${CHECK_DEFINED_REQUIRE}
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REJECT ${CHECK_DEFINED_REJECT})
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try_run(
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run_result compile_result "${CMAKE_CURRENT_BINARY_DIR}/check_${feature}"
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"${CMAKE_CURRENT_BINARY_DIR}/cpu_features/check_cpu_features.cpp"
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COMPILE_DEFINITIONS ${flags}
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COMPILE_OUTPUT_VARIABLE compile_output
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RUN_OUTPUT_VARIABLE run_output)
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if("${run_result}" EQUAL 0)
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set(${output_var}
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"${run_output}"
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PARENT_SCOPE)
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elseif(NOT ${compile_result})
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message(FATAL_ERROR "Failed to compile: ${compile_output}")
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else()
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message(FATAL_ERROR "Failed to run: ${run_output}")
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endif()
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endfunction()
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set(LIBC_CPU_FEATURES "" CACHE PATH "supported CPU features")
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set(LIBC_CPU_FEATURES "" CACHE PATH "Host supported CPU features")
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if(CMAKE_CROSSCOMPILING)
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_intersection(cpu_features "${ALL_CPU_FEATURES}" "${LIBC_CPU_FEATURES}")
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@ -135,13 +68,18 @@ if(CMAKE_CROSSCOMPILING)
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endif()
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set(LIBC_CPU_FEATURES "${cpu_features}")
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else()
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# Populates the LIBC_CPU_FEATURES list.
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# Use -march=native only when the compiler supports it.
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include(CheckCXXCompilerFlag)
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CHECK_CXX_COMPILER_FLAG("-march=native" COMPILER_SUPPORTS_MARCH_NATIVE)
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if(COMPILER_SUPPORTS_MARCH_NATIVE)
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_check_defined_cpu_feature(LIBC_CPU_FEATURES MARCH native)
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# Populates the LIBC_CPU_FEATURES list from host.
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try_run(
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run_result compile_result "${CMAKE_CURRENT_BINARY_DIR}/check_${feature}"
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"${CMAKE_CURRENT_BINARY_DIR}/cpu_features/check_cpu_features.cpp"
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COMPILE_DEFINITIONS ${LIBC_COMPILE_OPTIONS_NATIVE}
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COMPILE_OUTPUT_VARIABLE compile_output
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RUN_OUTPUT_VARIABLE run_output)
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if("${run_result}" EQUAL 0)
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set(LIBC_CPU_FEATURES "${run_output}")
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elseif(NOT ${compile_result})
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message(FATAL_ERROR "Failed to compile: ${compile_output}")
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else()
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_check_defined_cpu_feature(LIBC_CPU_FEATURES)
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message(FATAL_ERROR "Failed to run: ${run_output}")
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endif()
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endif()
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@ -186,20 +186,15 @@ function(add_implementation name impl_name)
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cmake_parse_arguments(
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"ADD_IMPL"
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"" # Optional arguments
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"MARCH" # Single value arguments
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"REQUIRE;REJECT;SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # Multi value arguments
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"" # Single value arguments
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"REQUIRE;SRCS;HDRS;DEPENDS;COMPILE_OPTIONS" # Multi value arguments
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${ARGN})
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compute_flags(flags
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MARCH ${ADD_IMPL_MARCH}
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REQUIRE ${ADD_IMPL_REQUIRE}
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REJECT ${ADD_IMPL_REJECT}
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)
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add_entrypoint_object(${impl_name}
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NAME ${name}
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SRCS ${ADD_IMPL_SRCS}
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HDRS ${ADD_IMPL_HDRS}
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DEPENDS ${ADD_IMPL_DEPENDS}
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COMPILE_OPTIONS ${ADD_IMPL_COMPILE_OPTIONS} ${flags} -O2
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COMPILE_OPTIONS ${ADD_IMPL_COMPILE_OPTIONS}
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)
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get_fq_target_name(${impl_name} fq_target_name)
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set_target_properties(${fq_target_name} PROPERTIES REQUIRE_CPU_FEATURES "${ADD_IMPL_REQUIRE}")
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@ -210,17 +205,6 @@ endfunction()
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# memcpy
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# ------------------------------------------------------------------------------
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# include the relevant architecture specific implementations
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if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/${LIBC_TARGET_ARCHITECTURE}/memcpy.cpp)
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elseif(${LIBC_TARGET_ARCHITECTURE_IS_AARCH64})
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/${LIBC_TARGET_ARCHITECTURE}/memcpy.cpp)
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#Disable tail merging as it leads to lower performance
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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mllvm --tail-merge-threshold=0")
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else()
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/memcpy.cpp)
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endif()
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function(add_memcpy memcpy_name)
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add_implementation(memcpy ${memcpy_name}
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SRCS ${MEMCPY_SRC}
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@ -235,8 +219,23 @@ function(add_memcpy memcpy_name)
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endfunction()
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if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
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add_memcpy(memcpy MARCH native)
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/x86_64/memcpy.cpp)
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add_memcpy(memcpy_x86_64_opt_sse2 COMPILE_OPTIONS -march=k8 REQUIRE SSE2)
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add_memcpy(memcpy_x86_64_opt_sse4 COMPILE_OPTIONS -march=nehalem REQUIRE SSE4_2)
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add_memcpy(memcpy_x86_64_opt_avx2 COMPILE_OPTIONS -march=haswell REQUIRE AVX2)
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add_memcpy(memcpy_x86_64_opt_avx512 COMPILE_OPTIONS -march=skylake-avx512 REQUIRE AVX512F)
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add_memcpy(memcpy_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_memcpy(memcpy)
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elseif(${LIBC_TARGET_ARCHITECTURE_IS_AARCH64})
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/aarch64/memcpy.cpp)
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# Disable tail merging as it leads to lower performance.
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# Note that '-mllvm' needs to be prefixed with 'SHELL:' to prevent CMake flag deduplication.
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add_memcpy(memcpy_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE}
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COMPILE_OPTIONS "SHELL:-mllvm --tail-merge-threshold=0")
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add_memcpy(memcpy COMPILE_OPTIONS "SHELL:-mllvm --tail-merge-threshold=0")
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else()
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set(MEMCPY_SRC ${LIBC_SOURCE_DIR}/src/string/memcpy.cpp)
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add_memcpy(memcpy_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_memcpy(memcpy)
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endif()
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@ -258,8 +257,14 @@ function(add_memset memset_name)
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endfunction()
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if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
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add_memset(memset MARCH native)
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add_memset(memset_x86_64_opt_sse2 COMPILE_OPTIONS -march=k8 REQUIRE SSE2)
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add_memset(memset_x86_64_opt_sse4 COMPILE_OPTIONS -march=nehalem REQUIRE SSE4_2)
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add_memset(memset_x86_64_opt_avx2 COMPILE_OPTIONS -march=haswell REQUIRE AVX2)
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add_memset(memset_x86_64_opt_avx512 COMPILE_OPTIONS -march=skylake-avx512 REQUIRE AVX512F)
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add_memset(memset_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_memset(memset)
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else()
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add_memset(memset_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_memset(memset)
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endif()
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@ -282,15 +287,13 @@ function(add_bzero bzero_name)
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endfunction()
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if(${LIBC_TARGET_ARCHITECTURE_IS_X86})
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add_bzero(bzero MARCH native)
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add_bzero(bzero_x86_64_opt_sse2 COMPILE_OPTIONS -march=k8 REQUIRE SSE2)
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add_bzero(bzero_x86_64_opt_sse4 COMPILE_OPTIONS -march=nehalem REQUIRE SSE4_2)
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add_bzero(bzero_x86_64_opt_avx2 COMPILE_OPTIONS -march=haswell REQUIRE AVX2)
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add_bzero(bzero_x86_64_opt_avx512 COMPILE_OPTIONS -march=skylake-avx512 REQUIRE AVX512F)
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add_bzero(bzero_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_bzero(bzero)
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else()
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add_bzero(bzero_opt_host COMPILE_OPTIONS ${LIBC_COMPILE_OPTIONS_NATIVE})
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add_bzero(bzero)
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endif()
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# ------------------------------------------------------------------------------
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# Add all other relevant implementations for the native target.
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# ------------------------------------------------------------------------------
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if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
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include(${LIBC_TARGET_ARCHITECTURE}/CMakeLists.txt)
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endif()
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@ -1 +0,0 @@
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add_memcpy("memcpy_${LIBC_TARGET_ARCHITECTURE}")
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@ -1,14 +0,0 @@
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add_memcpy("memcpy_${LIBC_TARGET_ARCHITECTURE}_opt_none" REJECT "${ALL_CPU_FEATURES}")
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add_memcpy("memcpy_${LIBC_TARGET_ARCHITECTURE}_opt_sse" REQUIRE "SSE" REJECT "SSE2")
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add_memcpy("memcpy_${LIBC_TARGET_ARCHITECTURE}_opt_avx" REQUIRE "AVX" REJECT "AVX2")
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add_memcpy("memcpy_${LIBC_TARGET_ARCHITECTURE}_opt_avx512f" REQUIRE "AVX512F")
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add_memset("memset_${LIBC_TARGET_ARCHITECTURE}_opt_none" REJECT "${ALL_CPU_FEATURES}")
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add_memset("memset_${LIBC_TARGET_ARCHITECTURE}_opt_sse" REQUIRE "SSE" REJECT "SSE2")
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add_memset("memset_${LIBC_TARGET_ARCHITECTURE}_opt_avx" REQUIRE "AVX" REJECT "AVX2")
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add_memset("memset_${LIBC_TARGET_ARCHITECTURE}_opt_avx512f" REQUIRE "AVX512F")
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add_bzero("bzero_${LIBC_TARGET_ARCHITECTURE}_opt_none" REJECT "${ALL_CPU_FEATURES}")
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add_bzero("bzero_${LIBC_TARGET_ARCHITECTURE}_opt_sse" REQUIRE "SSE" REJECT "SSE2")
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add_bzero("bzero_${LIBC_TARGET_ARCHITECTURE}_opt_avx" REQUIRE "AVX" REJECT "AVX2")
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add_bzero("bzero_${LIBC_TARGET_ARCHITECTURE}_opt_avx512f" REQUIRE "AVX512F")
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@ -196,6 +196,8 @@ function(add_libc_multi_impl_test name)
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libc_string_unittests
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DEPENDS
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${fq_config_name}
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COMPILE_OPTIONS
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${LIBC_COMPILE_OPTIONS_NATIVE}
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${ARGN}
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)
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else()
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