The code in this commit was written by Marcell Fischbach & Benedikt Meurer.
See [Mantis#5324](http://caml.inria.fr/mantis/view.php?id=5324) for some
context.
The code (which was originally written against 3.12) was ported to trunk by
doing
```bash
git clone https://github.com/bmeurer/ocaml-experimental/
cd ocaml-experimental
git diff master...linear-scan-register-allocator > t.diff
```
and then applying the diff by hand.