Ben Gamari authored Jul 20, 2016 and Ben Gamari committed Jul 20, 2016

Previously instIsVisible had completely broken the laziness of
lookupInstEnv' since it would examine is_dfun_name to check the name of
the defining module (to know whether it is an interactive module). This
resulted in the visibility check drawing in an interface file
unnecessarily. This contributed to the unnecessary regression in
compiler allocations reported in #12367.

Test Plan: Validate, check nofib changes

Reviewers: simonpj, ezyang, austin

Reviewed By: ezyang

Subscribers: thomie, ezyang

Differential Revision: https://phabricator.haskell.org/D2411

GHC Trac Issues: #12367