[GHC] #14929: Program compiled with -O2 exhibits much worse performance

[GHC]

#14929: Program compiled with -O2 exhibits much worse performance
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           Reporter:  mpickering     |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           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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 A user on reddit reports that compiling the program with `-O2` makes his
 program use a lot more memory.

 https://www.reddit.com/r/haskell/comments/84qovv/an_example_of_code_where_ghcs_o2_makes_things/

 It runs in constant memory without `-O2` and leaks memory with `-O2. It
 seems worth investigating as
 the example is quite small (< 1000 lines) and self-contained.

 https://github.com/luispedro/TestingNGLESS

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14929>
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