The GitHub readme links to a scholarly thesis discussing the general approach[0], as well as to the author's own dissertation[1] on this specific project (which "aims to investigate the practical viability" of [0] "by building the technology into a real compiler" for empirical evaluation on real-world hardware). Region inference is discussed throughout [0], and extensively in Chapter 9.

[0] https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-908.pdf

[1] http://nathancorbyn.com/nc513.pdf