[commit: ghc] master: ignore RealWorld in size_expr; flag to keep w/w from creating sharing (af12cf6)

[Nicolas Frisby]

Repository : http://darcs.haskell.org/ghc.git/

On branch  : master

https://github.com/ghc/ghc/commit/af12cf66d1a416a135cb98b86717aba2cd247e1a

>---------------------------------------------------------------

commit af12cf66d1a416a135cb98b86717aba2cd247e1a
Author: Nicolas Frisby <nicolas.frisby at gmail.com>
Date:   Thu Apr 11 12:48:11 2013 +0100

    ignore RealWorld in size_expr; flag to keep w/w from creating sharing
    
    size_expr now ignores RealWorld lambdas, arguments, and applications.
    
    Worker-wrapper previously removed all lambdas from a function, if they
    were all unused. Removing *all* value lambdas is no longer
    allowed. Instead (\_ -> E) will become (\_void -> E), where it used to
    become E. The previous behavior can be recovered via the new
    -ffun-to-thunk flag.
    
    Nofib notables:
    
    ----------------------------------------------------------------
            Program               O2          O2 newly ignoring RealWorld
                                              and not turning function
                                              closures into thunks
    ----------------------------------------------------------------
    
     Allocations
    
      comp_lab_zift            333090392%           -5.0%
    reverse-complem            155188304%           -3.2%
    
            rewrite             15380888%           +4.0%
             boyer2              3901064%           +7.5%
    
    rewrite previously benefited from fortunate LoopBreaker choice that is
    now disrupted.
    
    A function in boyer2 goes from $wonewayunify1 size 700 to size 650,
    thus gets inlined into rewritelemmas, thus exposing a parameter
    scrutinisation, thus allowing SpecConstr, which unfortunately involves
    reboxing.
    
    Run Time
    
     fannkuch-redux                 7.89%          -15.9%
    
                hpg                 0.25%           +5.6%
               wang                 0.21%           +5.8%
    
    /shrug

 compiler/coreSyn/CoreUnfold.lhs    | 51 +++++++++++++++++++++++---------------
 compiler/main/DynFlags.hs          |  2 ++
 compiler/specialise/SpecConstr.lhs |  2 +-
 compiler/stranal/WwLib.lhs         | 24 +++++++++++++++---
 docs/users_guide/flags.xml         | 11 ++++++++
 5 files changed, 65 insertions(+), 25 deletions(-)


Diff suppressed because of size. To see it, use:

    git show af12cf66d1a416a135cb98b86717aba2cd247e1a