Matthew Pickering authored Mar 19, 2018 and Ben Gamari committed Mar 19, 2018

Runs another specialisation pass towards the end of the optimisation
pipeline. This can catch specialisation opportunities which arose from
the previous specialisation pass or other inlining.

You might want to use this if you are you have a type class method
which returns a constrained type. For example, a type class where one
of the methods implements a traversal.

It is not enabled by default or any optimisation level. Only by
manually enabling the flag `-flate-specialise`.

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4457