[compiler-rt] [compiler-rt][AArch64] Provide basic implementations of SME memcpy/memmove in case of strictly aligned memory access (PR #138250)

[Sander de Smalen via llvm-commits]

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@@ -22,3 +23,46 @@ const void *__arm_sc_memchr(const void *src, int c,
 
   return NULL;
 }
+
+#ifndef __ARM_FEATURE_UNALIGNED
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sdesmalen-arm wrote:

To avoid creating many different variants and various ifdefs, does it make sense to choose the implementation (either `sme-libc-mem-routines.S` (optimised) or `sme-libc-routines.c` (basic)) in CMakeLists.txt ? That way we can also let cmake emit a warning that the unoptimised SME routines are chosen, because of the constraints given by the compilation flags to compiler-rt.

https://github.com/llvm/llvm-project/pull/138250