[llvm] [Support] Add Arm NEON implementation for `llvm::xxh3_64bits` (PR #99634)

[Daniel Bertalan via llvm-commits]

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@@ -47,6 +47,19 @@
 
 #include <stdlib.h>
 
+#if !defined(LLVM_XXH_USE_NEON)
+#if (defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)) &&      \
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BertalanD wrote:

MSVC proper does not define `__aarch64__`, though: https://godbolt.org/z/qhY1x4P4G. But the NEON intrinsics this code uses work there, too.

https://github.com/llvm/llvm-project/pull/99634