GHC-6.4.1 much slower than GHC-6.4

[Christian Maeder]

I've looked at the last columns (inherited %) and spotted
the following lines in Mirko's profiles:

for ghc-6.4.1:
   gen_interesting        PCP.Interesting 93.8   92.5
    suc                   PCP.Suc         33.4   35.0
     suc                  PCP.Rules.Suc   33.2   34.9
      exclusion           PCP.Rules.Excl  32.4   34.1

for ghc-6.4:
   gen_interesting        PCP.Interesting 75.5   67.5
    suc                   PCP.Suc          9.5   10.8
     suc_rules            PCP.Suc          9.5   10.8
      suc                 PCP.Rules.Suc    9.1   10.3
       exclusion          PCP.Rules.Excl   6.4    6.8

(Before the first "suc" after "gen_interesting" I've omitted many lines)

Simon Marlow wrote:
> 
> If you can find the root of the computation that is being evaluated
> multiple times with 6.4.1, that would help a great deal.  The call-tree
> on the time profile should help a lot, and you can narrow it down by
> inserting {-# SCC #-} annotations.  Basically we want to know which
> expression is being evaluated multiple times.