[llvm] [PreISelIntrinsicLowering] Support producing memset_pattern16 when loading from constant global (PR #129220)

[Nikita Popov via llvm-commits]

nikic wrote:

I'm not sure I understand why we need to do this. That is, shouldn't LIR be passing the pattern directly as an argument to experimental.memset.pattern and leave it to intrinsic lowering to create the global, instead of creating the global itself?

https://github.com/llvm/llvm-project/pull/129220