Draft: DmdAnal: Make exnDiv behave like topDiv
... except for the purposes of dead code eliminaiton.
As far as DmdAnal is concerned, topDiv
and exnDiv
used to differ simply in
their defaultArgDmd
. NoFib suggests that nothing is lost by making the
defaultArgDmd
of exnDiv
return topDmd
instead of absDmd
.
(Of course the main purpose of exnDiv
remains: dead code elimination.)
In the interest of simplification we should make topDiv
and exnDiv
as
similar as possible.