[GHC] #3064: Very long compile times with type functions

[GHC]

#3064: Very long compile times with type functions
-------------------------------------------+--------------------------------
  Reporter:  simonpj                       |          Owner:                  
      Type:  bug                           |         Status:  new             
  Priority:  low                           |      Milestone:  7.0.1           
 Component:  Compiler (Type checker)       |        Version:  6.10.1          
Resolution:                                |       Keywords:                  
        Os:  Unknown/Multiple              |   Architecture:  Unknown/Multiple
   Failure:  Compile-time performance bug  |     Difficulty:  Unknown         
  Testcase:                                |      Blockedby:                  
  Blocking:                                |        Related:                  
-------------------------------------------+--------------------------------
Changes (by simonpj):

  * owner:  igloo =>
  * status:  closed => new
  * resolution:  fixed =>


Comment:

 I'm re-opening this for HEAD, following D's recent patches.  The
 definition at the bottom of `T3064.hs` looks like
 {{{
 test14 :: IO ()
 test14 = runCA(newRgn(newRgn(newRgn(newRgn(newRgn(newRgn(newRgn(newRgn(
                newRgn(newRgn(newRgn(newRgn(return())))))))))))))
 }}}
 (Despite its name, that looks like 12 nested applications of `newRgn` to
 me.)  I tried doubling the number of nested calls, and re-doubling, and
 compile with `+RTS -s`:
 {{{
 # nested calls     Bytes alloc'd by HEAD       Bytes alloc'd by 7.4.1
 ----------------------------------------------------------------------
       12                  86M                        68M
       24                 205M                       105M
       48                 920M                       241M
 }}}
 Something is amiss here.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3064#comment:14>
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