Performance degrades from -O1 to -O2
GHC seems to get stuck at SpecConstr stage when compiling.
I've managed to get the example down to what appears to be minimal but making a number of minor changes makes the compilation go through quickly:
- removing one of the
- using "-fno-spec-constr" (unsuprisingly).
I can't reproduce it on 8.0.2.
In larger examples I was able to get memory and cpu to sky rocket quite quickly but I appear to have lost some of that behaviour when paring down the example.