[GHC] #14468: Why does alanz's branch blow up GHC's heap?

[GHC]

#14468: Why does alanz's branch blow up GHC's heap?
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           Reporter:  bgamari        |             Owner:  (none)
               Type:  task           |            Status:  new
           Priority:  high           |         Milestone:  8.4.1
          Component:  Compiler       |           Version:  8.2.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 alanz mentioned that moving all of GHC's `Data` instances
 [[https://git.haskell.org/ghc.git/blob/12028239b597e17fb3f3734c6b494e127be58e0c:/compiler/hsSyn/HsInstances.hs|instances]]
 to a new module causes the stage1 compile to run out of memory during
 compilation (he has 8 GB of memory). This is rather suspicious as this
 module isn't terribly large. IIRC typechecking time may be non-linear in
 program size, but I don't see why it would be non-linear in space.
 Investigate.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14468>
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