On Wed, Nov 24, 2021 at 06:32:04PM -0500, Viktor Dukhovni wrote:
Yes exactly. And it would not be hard to adapt the existing CSE pass to support this. Just needs doing.
A ticket and a repo case would be really helpful.
I'll do my best to construct a standalone reproducer that is not mired in ByteString code. The ByteString example should not be too difficult to mimmic in code that relies only on base.
Just noticed a complication, it seems that the placemnt of the IO state token in the join point argument list is non-deterministic, so I'm starting to see join points in which the argument lists are permuted, with an equivalent permutation at the jump/call site... :-( Two exit points returning equivalent data, the first returns early, the second returns after first performing some I/O: return $ Result valid acc (ptr `minusPtr` start) become respectively (ipv2 and w3 are IO state tokens): 1. jump exit2 ww4 ww5 valid ipv2 -- acc ptr valid s# 2. jump exit3 ww4 ww5 w3 valid -- acc ptr s# valid So the join points are then only alpha equivalent up to argument permutation: join { exit2 :: Word# -> Addr# -> Bool -> State# RealWorld -> Maybe (Int, ByteString) exit2 (ww4 :: Word#) (ww5 :: Addr#) (valid :: Bool) (ipv2 :: State# RealWorld) = ... join { exit3 :: Word# -> Addr# -> State# RealWorld -> Bool -> Maybe (Int, ByteString) exit3 (ww4 :: Word#) (ww5 :: Addr#) (w2 :: State# RealWorld) (valid :: Bool) = ... I don't how argument lists to join points are ordered, would it be possible to make them predictably consistent? -- Viktor.