[compiler-rt] [AArch64][compiler-rt] Add memcpy, memset, memmove, memchr builtins. (PR #77496)

[David Green via llvm-commits]

davemgreen wrote:

I dont usually follow compiler-rt commits, so didnt see this. memcpy and friends can be used a lot - performance for them can be critical and a lot of time has been spent over the years trying to optimize them.

Is the idea that these are auto-vectorized? And so might use the SME engine for the copy? I'm not sure that is happening in the current version I have, and single byte memcpys sounds pretty slow. And that's before other considerations like alignment and systems wanting platform specific routines. I would add Wilco (I'm not sure what his username is), he has done a lot of work on these kinds of routines and it would be good to get his input.

https://github.com/llvm/llvm-project/pull/77496