+--So that we don't have orphan instances, this goes here or in CmmExpr.
+--At least UserOfLocalRegs (ZLast Last) is needed (Last defined elsewhere),
+--but there's no need for non-Haskell98 instances for that.
+instance UserOfLocalRegs a => UserOfLocalRegs (ZLast a) where
+ foldRegsUsed f z (LastOther l) = foldRegsUsed f z l
+ foldRegsUsed _f z LastExit = z
+
+