[GHC] #12776: Panic Simplifier ticks exhausted since ghc 8

[GHC]

#12776: Panic Simplifier ticks exhausted since ghc 8
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        Reporter:  sjcjoosten        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by sjcjoosten):

 * priority:  normal => high
 * failure:  None/Unknown => Compile-time crash or panic


@@ -5,1 +5,1 @@
- sjoosten:ghcCompileBug sjc$ ghc-8.1.20161028 --make Main.hs -O2
+ sjoosten:ghcCompileBug sjc$ ghc-8.1.20161028 --make Factorize.hs -O2

New description:

 I'm getting a panic! in GHC 8.0.1 and in 8.1.20161028


 {{{
 sjoosten:ghcCompileBug sjc$ ghc-8.1.20161028 --make Factorize.hs -O2
 [1 of 2] Compiling Factorize        ( Factorize.hs, Factorize.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.1.20161028 for x86_64-apple-darwin):
         Simplifier ticks exhausted
   When trying UnfoldingDone $slast_s_s1IU
   To increase the limit, use -fsimpl-tick-factor=N (default 100)
   If you need to do this, let GHC HQ know, and what factor you needed
   To see detailed counts use -ddump-simpl-stats
   Total ticks: 18241
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1076:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in
 ghc:Outputable
         pprPanic, called at compiler/simplCore/SimplMonad.hs:199:31 in
 ghc:SimplMonad

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 Attached is some code which I tried to make as small as possible (it
 therefore does not make sense, but it reproduces the panic). The panic!
 only occurs with -O2 (I need the -O2 switch to optimise the automatically
 generated Haskell code).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12776#comment:1>
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