[GHC] #5075: CPR optimisation for sum types if only one constructor is used

[GHC]

#5075: CPR optimisation for sum types if only one constructor is used
---------------------------------+------------------------------------------
    Reporter:  batterseapower    |       Owner:  simonpj         
        Type:  feature request   |      Status:  patch           
    Priority:  normal            |   Milestone:  7.6.2           
   Component:  Compiler          |     Version:  7.0.3           
    Keywords:                    |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown    
  Difficulty:  Unknown           |    Testcase:                  
   Blockedby:                    |    Blocking:                  
     Related:                    |  
---------------------------------+------------------------------------------

Comment(by simonpj@…):

 commit d3b8991be3875302ca6d1a4ef6e72891e9567dd5
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Thu Jan 24 14:50:50 2013 +0000

     Introduce CPR for sum types (Trac #5075)

     The main payload of this patch is to extend CPR so that it
     detects when a function always returns a result constructed
     with the *same* constructor, even if the constructor comes from
     a sum type.  This doesn't matter very often, but it does improve
     some things (results below).

     Binary sizes increase a little bit, I think because there are more
     wrappers.  This with -split-objs.  Without split-ojbs binary sizes
     increased by 6% even for HelloWorld.hs.  It's hard to see exactly why,
     but I think it was because System.Posix.Types.o got included in the
     linked binary, whereas it didn't before.

             Program           Size    Allocs   Runtime   Elapsed  TotalMem
               fluid          +1.8%     -0.3%      0.01      0.01     +0.0%
                 tak          +2.2%     -0.2%      0.02      0.02     +0.0%
                ansi          +1.7%     -0.3%      0.00      0.00     +0.0%
           cacheprof          +1.6%     -0.3%     +0.6%     +0.5%     +1.4%
             parstof          +1.4%     -4.4%      0.00      0.00     +0.0%
             reptile          +2.0%     +0.3%      0.02      0.02     +0.0%
     ----------------------------------------------------------------------
                 Min          +1.1%     -4.4%     -4.7%     -4.7%    -15.0%
                 Max          +2.3%     +0.3%     +8.3%     +9.4%    +50.0%
      Geometric Mean          +1.9%     -0.1%     +0.6%     +0.7%     +0.3%

     Other things in this commit
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * Got rid of the Lattice class in Demand

     * Refactored the way that products and newtypes are
       decomposed (no change in functionality)

  compiler/basicTypes/BasicTypes.lhs  |   17 ++
  compiler/basicTypes/DataCon.lhs     |   60 -----
  compiler/basicTypes/Demand.lhs      |  429
 ++++++++++++++++++-----------------
  compiler/basicTypes/MkId.lhs        |   11 +-
  compiler/cmm/CLabel.hs              |    1 -
  compiler/coreSyn/CoreLint.lhs       |   12 +-
  compiler/coreSyn/CoreSyn.lhs        |    7 +-
  compiler/deSugar/DsCCall.lhs        |   45 ++++-
  compiler/deSugar/DsForeign.lhs      |    2 +-
  compiler/prelude/PrelRules.lhs      |    2 +-
  compiler/simplCore/Simplify.lhs     |    5 +-
  compiler/specialise/SpecConstr.lhs  |    2 +-
  compiler/stranal/DmdAnal.lhs        |   49 +++-
  compiler/stranal/WwLib.lhs          |  210 ++++++++----------
  compiler/types/Coercion.lhs         |   62 ++++--
  compiler/types/FamInstEnv.lhs       |   26 +--
  compiler/types/TyCon.lhs            |   25 ++-
  compiler/types/Type.lhs             |   26 +--
  compiler/vectorise/Vectorise/Exp.hs |   10 +-
  19 files changed, 515 insertions(+), 486 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5075#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler