[GHC] #12944: ghc master (8.1.20161206) panics with assertion failure with devel2 flavor and -O

[GHC]

#12944: ghc master (8.1.20161206) panics with assertion failure with devel2 flavor
and -O
-------------------------------------+-------------------------------------
        Reporter:  pacak             |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
  (CodeGen)                          |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2844
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"0d213c18b6962bb65e2b3035a258dd3f5bf454dd/ghc" 0d213c1/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0d213c18b6962bb65e2b3035a258dd3f5bf454dd"
 UniqSupply: Use full range of machine word

 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
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12944#comment:7>
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