• simonpj@microsoft.com's avatar
    Be more conservative about duplicating continuations · da107045
    simonpj@microsoft.com authored
    Roman found that GHC was duplicating continuations that arose (essentially)
    from uses of 'seq', or strict constructors.  This fixes the problem;
    see the comments mkDupableCont (the Select case with a single alternative).
    
    I'm a little concerned that this may also miss useful case-of-case
    tranformations, so I'd like to know if anyone finds that this patch
    makes performance worse.
    
    To make it a bit more gung-ho, one could check for all the binders
    being dead, before choosing this new, conservative alternative.
    
    da107045
Simplify.lhs 72.9 KB