Compiler optimizations questions for ghc 6.10...

Max Bolingbroke batterseapower at hotmail.com
Wed Feb 18 04:38:31 EST 2009


2009/2/18 Max Bolingbroke <batterseapower at hotmail.com>:
> Yes - GHC wants to share the work of (maxBound-x)`div`10 between
> several partial applications of "digit". This is usually a good idea,
> but in this case it sucks because it's resulted in a massively
> increased arity. IMHO GHC should fix this by:
> * Marking divInt# INLINE in the base library. This would result in
> your code would just containing uses of quotInt#
> * Making some operations cheap even if they may fail
> (PrimOp.primpOpIsCheap should change). Though this might mean that we
> turn non-terminating programs into terminating ones (such operations
> get pushed inside lambdas) but this is consistent with our treatment
> of lambdas generally.

Just to let you know - I've filed a bug (#3034
http://hackage.haskell.org/trac/ghc/ticket/3034) about this issue.
I've taken the liberty of adding you to the CC list so you can keep
track of the problem.

Cheers,
Max


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