-- The heap high water mark is the larger of virtHp and hwHp.  The latter is
-- only records the high water marks of forked-off branches, so to find the
-- heap high water mark you have to take the max of virtHp and hwHp.  Remember,
-- virtHp never retreats!
--
-- Note Jan 04: ok, so why do we only look at the virtual Hp??

heapHWM :: HeapUsage -> VirtualHpOffset
heapHWM = virtHp
heapHWM :: HeapUsage -> VirtualHpOffset
heapHWM = virtHp
heapHWM = virtHp