[GHC] #9476: Implement late lambda-lifting

[GHC]

#9476: Implement late lambda-lifting
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        Reporter:  simonpj           |                Owner:  sgraf
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  7.8.2
      Resolution:  fixed             |             Keywords:  LateLamLift
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8763 #13286      |  Differential Rev(s):  Phab:D5224
       Wiki Page:  LateLamLift       |
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Comment (by simonpj):

 Interesting.  The fact that this program has a tiny inner loop makes it
 feasibly to dig into.

 If I were doing this, I think the next thing I'd try would be to histogram
 the heap contents (info-pointer, number of closures with that info
 pointer) at each GC.  This is roughly want heap profiling can do, but it
 may collapse too many things into one.

 More ambitiously, the heap profiler is supposed to be able to plot "lag";
 that is, stuff that is kept alive, but is never subsequently referenced.
 If that is still working it'd be interesting to know whether or not the
 extra residency is hanging onto stuff that is never subsequently
 referenced.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9476#comment:61>
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