[GHC] #15304: Huge increase of compile time and memory use from 8.0.2 to 8.2.2 or 8.4.2

[GHC]

#15304: Huge increase of compile time and memory use from 8.0.2 to 8.2.2 or 8.4.2
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           Reporter:  NathanWaivio   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.1
          Component:  Compiler       |           Version:  8.4.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  performance bug
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I am the author of the cl3 library on Hackage.  I have noticed a huge
 increase of compile time and memory use when testing 8.2.2 and 8.4.2.
 ghc-8.0.2 compiled in 4:17.33 using 3.5 GB.  ghc-8.2.2 compiled in
 26:40.15 using 32.8 GB. This is an increase of 6x in time and 9x in
 memory.  This is not all bad, my nbody benchmark has improved about 35%
 between ghc-8.0.2 and ghc-8.4.2 so the increased compilation time and
 memory usage are producing much better runtime performance.  I am
 interested if you could suggest some workarounds to help others compile on
 systems with less resources.  I have 64GB memory in my system and would
 like to test out some -fno-* GHC Options.  Could you point me in the right
 direction?  The library is almost entirely pure functions.  I am also
 interested in other options, like if there are ways to rewrite things to
 make it easier on the compiler or using NOINLINE on a trouble spot and how
 to find that trouble spot.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15304>
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