[GHC] #9445: GHC Panic: Tick Exhausted with high factor

[GHC]

#9445: GHC Panic: Tick Exhausted with high factor
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       Reporter:  adinapoli          |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.8.3
       Keywords:  panic              |        Operating System:  MacOS X
   Architecture:  Unknown/Multiple   |         Type of failure:
     Difficulty:  Unknown            |  None/Unknown
     Blocked By:                     |               Test Case:
Related Tickets:  5539               |                Blocking:
                                     |  Differential Revisions:
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 Hello guys,

 this is an old bug which has been reported so many times that I'm not sure
 this will be noise or something useful.

 In a nutshell I have been hit by this bug installing the library "SFML",
 which relies heavily on FFI.
 The only interesting thing of this report is that it was necessary an very
 high simpl-factor to make the installation go through!

 Pre-bump:

 {{{
 Resolving dependencies...
 In order, the following will be installed:
 SFML-0.2.0.0 (reinstall)
 Warning: Note that reinstalls are always dangerous. Continuing anyway...
 Configuring SFML-0.2.0.0...
 Building SFML-0.2.0.0...
 Preprocessing library SFML-0.2.0.0...
 [...]
 [34 of 71] Compiling SFML.Graphics.Transform (
 dist/build/SFML/Graphics/Transform.hs,
 dist/build/SFML/Graphics/Transform.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.8.3 for x86_64-apple-darwin):
         Simplifier ticks exhausted
     When trying UnfoldingDone $j_sZQW{v} [lid]
     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: 2655928
 }}}

 And this was the magic line:

 {{{
 cabal install SFML --ghc-option=-fsimpl-tick-factor=1630
 }}}

 HTH, it turns out it's quite an annoying one! And yes, "1630" was the
 smaller factor which made the installation possible.

 Alfredo

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9445>
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