[GHC] #3116: missed opportunity for call-pattern specialisation

[GHC]

#3116: missed opportunity for call-pattern specialisation
-----------------------------------------+----------------------------------
    Reporter:  duncan                    |        Owner:                  
        Type:  run-time performance bug  |       Status:  closed          
    Priority:  normal                    |    Milestone:                  
   Component:  Compiler                  |      Version:  6.10.1          
    Severity:  normal                    |   Resolution:  fixed           
    Keywords:                            |   Difficulty:  Unknown         
    Testcase:  eyeball/T3116.hs          |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple          |  
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Changes (by simonpj):

  * testcase:  => eyeball/T3116.hs
  * status:  new => closed
  * resolution:  => fixed

Comment:

 The original (excellent) suggestion is implemented by this patch:
 {{{
 Wed Mar 25 09:52:05 GMT 2009  simonpj at microsoft.com
   * Improve mkDupableCont; and fix Trac #3116

   It turns out that, as a result of a change I made a few months ago to
   the representation of SimplCont, it's easy to solve the optimisation
   challenge posed by Trac #3116.  Hurrah.

   Extensive comments in Note [Duplicating StrictArg].


     M ./compiler/simplCore/SimplUtils.lhs -1 +1
     M ./compiler/simplCore/Simplify.lhs -19 +67
 }}}
 Now you get perfect code for the example!  Test in `eyeball/T3118.hs`.

 I'm going to close this ticket; if you like, you can open another for the
 more speculative idea you were proposing.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3116#comment:7>
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