AArch64-UEFI-LLVM-HelloWorld: uses GNU-EFI and CLang on ARM

https://github.com/tnishinaga/aarch64-uefi-llvm_helloworld

UEFI HelloWorld application with clang + lld + gnu-efi(header only)

This is a nonstandard build environment for UEFI, using GNU-EFI with clang (not efi-clang) on ARM not Intel. Last time I looked, GNU-EFI was Intel-centric and GCC-centric, so this is impressive.