Ben Gamari authored Dec 15, 2016 and Ben Gamari committed Dec 15, 2016

Currently uniques are 32-bits wide. 8 of these bits are for the unique
class, leaving only 24 for the unique number itself. This seems
dangerously small for a large project. Let's use the full range of the
native machine word.

We also add (now largely unnecessary) overflow check to ensure that the
unique number doesn't overflow.

Test Plan: Validate

Reviewers: simonmar, austin, niteria

Reviewed By: niteria

Subscribers: mpickering, thomie

Differential Revision: https://phabricator.haskell.org/D2844

GHC Trac Issues: #12944