6.8.3 against DoCon

[Simon Peyton-Jones]

| So, DoCon remains with  ghc-6.8.2  -- untill GHC fixes the problem.
|
| Hm ... a small module needs > 600 Mb instead of 80 Mb to compile,
| and the release is considered as a progress.
| All right, this may occur correct -- if the developers know what
| namely must be fixed, and also know how to fix it. If so, then I could
| believe.

I have looked into this a bit.  It's because GHC currently inlines every instance declaration bodily, code and all.  DoCon has a lot of instance declarations with a lot of code in them, so there's a tremendous amount of code duplication as a result of dictionary construction.

I've been working on a fix for this -- it bites every program, but DoCon especially -- but I have not yet managed to complete it.  I'm not quite sure why 6.8.3 is worse than 6.8.2, but both are bad.

I'm hoping for a dramatic improvement once I've done my fix.

Simon