[clang] [libc] [llvm] [AMDGPU] Implement variadic functions by IR lowering (PR #93362)

[Jon Chesterfield via llvm-commits]

JonChesterfield wrote:

Thanks @Pierre-vh, I think those are all applied. Also removed llvm:: from some other places, and remembered that llvm doesn't like the if () {braces} which are so useful for git merge not introducing bugs so removed the majority of those as well. Feel confident enough after reading through to mark it green? All it can do is take variadic functions from hard errors to probably working.

https://github.com/llvm/llvm-project/pull/93362