Simon Peyton Jones authored Feb 26, 2017 and David Feuer committed Feb 26, 2017

When studying simplCore/should_compile/T7785 I found that a long
chain of maps

  map f (map f (map f (map f (...))))

took an unreasonably long time to simplify.  The problem got
worse when I started inlining in the InitialPhase, which is how
I stumbled on it.

The solution turned  out to be rather simple.  It's described in

   Note [Occurence-analyse after rule firing]

in Simplify.hs

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D3190