Cmm output should exploit Unf=OtherCon []

It appears to me that generated Cmm does not take into account Unf= OtherCon [], which as far as I know indicates that something is known to be already forced. For example:

data S a = S {unS :: !a}

data Tree = Node !Tree !Tree | Leaf !Int

inc :: S Tree -> Tree
inc (S t) = case t of
  Leaf n   -> Leaf (n + 1)
  Node l r -> Node (inc (S l)) (inc (S r))

With GHC 8.8.4 and 8.10.2, I get the following worker function:

$winc :: Tree -> Tree
$winc
  = \ (ww_s1iY
         :: Tree
         Unf=OtherCon []) ->
      case ww_s1iY of {
        Node l_a137 r_a138 ->
          case $winc l_a137 of dt_X13T { __DEFAULT ->
          case $winc r_a138 of dt1_X13V { __DEFAULT ->
          Node dt_X13T dt1_X13V
          }
          };
        Leaf dt_d1hC -> Leaf (+# dt_d1hC 1#)
      }

I expected that $winc$ does not check for thunks, but it does:

[$winc_entry() //  [R2]
       ...
       c1kC:
           I64[Sp - 8] = c1kt;
           R1 = R2;
           Sp = Sp - 8;
           if (R1 & 7 != 0) goto c1kt; else goto c1ku;
       c1ku:
           call (I64[R1])(R1) returns to c1kt, args: 8, res: 8, upd: 8;
       c1kt:

It's quite common to use records with strict fields, and in all such cases we get worker functions with superfluous forcing like above.