Lennart Augustsson schrieb: > GHC doesn't normally do CSE. CSE can cause space leaks, so you can't do > it willy-nilly. > I'm sure there are some strict contexts where it could be done safely, > but I don't think ghc uses that information (yet).
Interestingly, it can only be switched off by -fno-cse, so I suppose there should be some cases of cse. C. > On Nov 27, 2006, at 08:34 , Christian Maeder wrote: > >> the following code does not run as fast as expected: >> >> modexp a e n = if e <= 0 then 1 else >> if even e >> then mod (modexp a (div e 2) n * modexp a (div e 2) n) n >> else mod (a * modexp a (e - 1) n) n >> >> it gets only fast if written as: >> >> modexp2 a e n = if e <= 0 then 1 else >> if even e >> then let d = modexp2 a (div e 2) n in mod (d * d) n >> else mod (a * modexp2 a (e - 1) n) n _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
