LLVM installation

Installing LLVM on macOS

• Better use macports in our experience, install LLVM first

• Then install llvm-select

• Then sudo port select llvm gives something like:

Available versions for llvm:
 	mp-llvm-10
	mp-llvm-11
 	mp-llvm-12 (active)
 	mp-llvm-devel
 	none

• You can chose the version you want to install: sudo port select llvm mp-llvm-11

• Now llvm-config should now be available.