patch applied (ghc): Re-engineer the derived Ord instance generation code (fix Trac #4019)

[Simon Peyton Jones]

Mon May 10 06:33:33 PDT 2010  simonpj at microsoft.com
  * Re-engineer the derived Ord instance generation code (fix Trac #4019)
    
  As well as fixing #4019, I rejigged the way that Ord instances are
  generated, which should make them faster in general.  See the 
  Note [Generating Ord instances].
  
  I tried to measure the performance difference from this change, but
  the #4019 fix only removes one conditional branch per iteration, and
  I couldn't measure a consistent improvement.  But still, tihs is
  better than before.

    M ./compiler/typecheck/TcGenDeriv.lhs -273 +281

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=ghc;a=darcs_commitdiff;h=20100510133333-1287e-b3c0eb04b4039eb0f7b2da3b6891c8530eff14dc.gz