If I wanted to do this sort of thing, I'd probably use either intrinsics or C directly -- the compiler is already good at dealing with both, and will probably d

If I wanted to do this sort of thing, I'd probably use either intrinsics or C directly -- the compiler is already good at dealing with both, and will probably do a better job than LLVM IR. The biggest reasons to drop to assembly is because there are high level constructs that the compiler is very unlikely to recognize and optimize effectively. Things like AES-NI, hardware RNGs, and similar.