Hi,
Hi!
I want to analyse the laziness of a data structure. To check how many nodes are constructed I use a global counter.
counter :: IORef Int counter = unsafePerformIO (newIORef 0)
This counter is increased every time the constructor is called by redefining the constructor OBDD as follows.
oBDD low var high = seq (unsafePerformIO (modifyIORef counter (+1))) (OBDD low var high)
This works fine. When I compile with optimisations the counter is always set to one no matter how many nodes are constructed. I thought this would be caused by inlining. Therefore I have added two NOINLINE pragmata.
{-# NOINLINE counter #-} {-# NOINLINE oBDD #-}
Although the counter doesn't work. Is there another optimisation that can cause harm? Is there something wrong with the pragmata?
Two comments: 1. There are other optimisations than inlining that can break sharing, e.g. common subexpression elimination, full-laziness-transformation. 2. I tested the following: {-# NOLINE counter #-} {-# INLINE oBDD #-} then the counter "seems" to work correct. In my opinion oBDD is an abstraction and can always be inlined. Cheer, David