[GHC] #12425: With -O1 and above causes ghc to use all available memory before being killed by OOM killer

[GHC]

#12425: With -O1 and above causes ghc to use all available memory before being
killed by OOM killer
-------------------------------------+-------------------------------------
           Reporter:  erikd          |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.0.2
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Other
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 I've just taken over an existing haskell package and in the process of
 getting it to work with ghc 8.0 discovered that when compiling one file
 ghc tires to use all my ram. It basically ends up using 40% of 16 Gig
 before being killed by the OOM (out-of-memory) killer.

 The project is at: https://github.com/erikd/conduit-find.git

 The problem can be reproduced by:
 {{{
 git clone https://github.com/erikd/conduit-find.git
 cd conduit-find
 git checkout test/ghc-8.0
 cabal sandbox init
 cabal install --dependencies-only
 cabal build
 }}}

 which on two of my machines fails building the `Data.Cond` module.

 This is regression, because this code compiles fine with ghc-7.10.3 and
 ghc-7.8.4.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12425>
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