[clang] [llvm] CodeGen: Add LibcallLoweringInfo analysis pass (PR #168622)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I think this should be NFC, assuming everything is working as intended. It seems that in some cases, certain targets are no longer lowering some functions to libcalls. In my case, I'm seeing `llvm.memset` intrinsics in wasm code get lowered to load/store loops rather than to `memset` calls. Currently investigating why the behavior changed there.

Is this with LTO? I think we have poor to nonexistent coverage of library info in some of the LTO configurations 




https://github.com/llvm/llvm-project/pull/168622