[GHC] #14414: Profiled program runs 2.5x faster than non-profiled

[GHC]

#14414: Profiled program runs 2.5x faster than non-profiled
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        Reporter:  Fuuzetsu          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 I must be missing something; I can't reproduce on Linux with GHC 8.2.1 and
 LLVM 3.9.1.

 ||= Flags                = ||= NCG =||= NCG =||= LLVM =||= LLVM =||
 ||                         ||= MUT =||= GC  =||= MUT  =||= GC   =||
 || `-O0`                   || 24.8  || 5.42  || 24.22  || 5.42   ||
 || `-O1`                   || 6.55  || 1.24  || 4.38   || 0.73   ||
 || `-O2`                   || 5.37  || 0.91  || 4.28   || 0.83   ||
 || `-O1 -prof`             || 8.68  || 1.68  || 7.78   || 1.36   ||
 || `-O2 -prof`             || 8.28  || 1.47  || 7.13   || 1.58   ||
 || `-O1 -prof -fprof-auto` || 17.63 || 1.72  || 17.01  || 1.95   ||
 || `-O2 -prof -fprof-auto` || 15.26 || 1.71  || 14.36  || 1.64   ||

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14414#comment:2>
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