[GHC] #14870: Runtime performance regression in 8.4

[GHC]

#14870: Runtime performance regression in 8.4
-------------------------------------+-------------------------------------
           Reporter:  bgamari        |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Runtime
  Unknown/Multiple                   |  performance bug
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 varosi [[https://mail.haskell.org/pipermail/glasgow-haskell-
 users/2018-February/026701.html|reports]] that the code for his project is
 slower in 8.4.1 than 8.2.2:

 > Yesterday I successfully compiled it with GHC 8.4.1-rc1. I got compiled
 it
 > with 8.2.2 and 8.0.2 as well and ran tests for about a minute each on my
 > Intel Core i7 machine on Windows 10 x64.
 >
 > I got this results:
 >
 > GHC 8.4.1-rc1
 > Average time: 61.87s
 >
 > GHC 8.2.2
 > Average time: 60.09s
 >
 > GHC 8.0.2
 > Average time: 67.07s
 >

 We should look into why.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14870>
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