Add -fspec-inline-join-points to SpecConstr
This patch addresses a problem that Roman found in SpecConstr. Consider: foo :: Maybe Int -> Maybe Int -> Int foo a b = let j b = foo a b in case b of Nothing -> ... Just n -> case a of Just m -> ... j (Just (n+1)) ... Nothing -> ... j (Just (n-1)) ... We want to make specialised versions for 'foo' for the patterns Nothing (Just v) (Just a) (Just b) Two problems, caused by the join point j. First, j does not scrutinise b, so j won't be specialised f for the (Just v) pattern. Second, j is defined where the free var 'a' is not evaluated. Both are solved by brutally inlining j at its call sites. This risks major code bloat, but it's relatively quick to implement. The flag -fspec-inline-join-points causes brutal inlining for a non-recursive binding of a function whose RHS contains calls of a recursive function The (experimental) flag is static for now, and I have not even documented it properly.