fix: assume AVX2 support on MSVC #25
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lemire
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Sep 7, 2024
| elseif(CMAKE_C_COMPILER_ID STREQUAL "MSVC") | ||
| message(STATUS "Assuming AVX2, SSE4.2, SSE4.1 support on MSVC") | ||
| target_compile_options(despacer PRIVATE /arch:AVX2) | ||
| target_compile_definitions(despacer PRIVATE __SSE4_1__ __SSE4_2__ __AVX2__) |
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As per the Microsoft documentation:
The __AVX__ preprocessor symbol is defined when the /arch:AVX, /arch:AVX2 or /arch:AVX512 compiler option is specified. The __AVX2__ preprocessor symbol is defined when the /arch:AVX2 or /arch:AVX512 compiler option is specified.
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I'd rather that the macros starting with _ not be manually set. Let the compiler do it.
lemire
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Sep 7, 2024
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| preBuildCommands "cmake -S ./ -B ./build && cmake --build ./build --config Release" | ||
| preBuildCommands "cmake -S ./ -B ./build -DBENCHMARKS=OFF -DUNIT_TESTS=OFF && cmake --build ./build --config Release" platform="posix" | ||
| preBuildCommands "cmake -G \"Ninja Multi-Config\" -S ./ -B ./build -DBENCHMARKS=OFF -DUNIT_TESTS=OFF && cmake --build ./build --config Release" platform="windows" |
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Are we assuming that Ninja is available and used?
lemire
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Sep 7, 2024
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lemire
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It is fine to enable AVX2 under Visual Studio when under x64, but I do not think we should be setting manually the feature macros (__AVX2__). It is likely buying us technical debt.
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MSVC doesn't have
-march=nativeoption so all the definitions are ignored resulting in no SIMD being used. This assumes that AVX2 is supported, which is a good compromise until runtime checking is implemented.