BLD: fallback to __builtin_prefetch on clang-cl with -mno-mmx
#2742
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`clang-cl` requires `MMX` for ``_mm_prefetch`. With `-mno-mmx`, `__MMX__` is undefined and the build fails in cache_control.h. Use `__builtin_prefetch` in this configuration; keep `_mm_prefetch` everywhere else. Fixes NumPy's CI failure on Windows without MMX.
jan-wassenberg
approved these changes
Oct 1, 2025
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clang-clrequiresMMXfor_mm_prefetch. With-mno-mmx,__MMX__is undefined and the build fails in cache_control.h. Use__builtin_prefetchin this configuration; keep_mm_prefetcheverywhere else. Fixes NumPy's CI failure on Windows without MMX.For further details, see #2737 (comment)