toBlockListEntryFirstFalseFallthrough :: CmmGraph -> [CmmBlock]
toBlockListEntryFirstFalseFallthrough g
  | mapNull m  = []
  | otherwise  = dfs setEmpty [entry_block]
  where
    m = toBlockMap g
    entry_id = g_entry g
    Just entry_block = mapLookup entry_id m

    dfs :: LabelSet -> [CmmBlock] -> [CmmBlock]
    dfs _ [] = []
    dfs visited (block:bs)
      | id `setMember` visited = dfs visited bs
      | otherwise              = block : dfs (setInsert id visited) bs'
      where id = entryLabel block
            bs' = foldr add_id bs (successors block)
            add_id id bs = case mapLookup id m of
                              Just b  -> b : bs
                              Nothing -> bs
toBlockListEntryFirstFalseFallthrough :: CmmGraph -> [CmmBlock]
toBlockListEntryFirstFalseFallthrough g
  | mapNull m  = []
  | otherwise  = dfs setEmpty [entry_block]
  where
    m = toBlockMap g
    entry_id = g_entry g
    Just entry_block = mapLookup entry_id m

    dfs :: LabelSet -> [CmmBlock] -> [CmmBlock]
    dfs _ [] = []
    dfs visited (block:bs)
      | id `setMember` visited = dfs visited bs
      | otherwise              = block : dfs (setInsert id visited) bs'
      where id = entryLabel block
            bs' = foldr add_id bs (successors block)
            add_id id bs = case mapLookup id m of
                              Just b  -> b : bs
                              Nothing -> bs
toBlockListEntryFirstFalseFallthrough g
  | mapNull m  = []
  | otherwise  = dfs setEmpty [entry_block]
  where
    m = toBlockMap g
    entry_id = g_entry g
    Just entry_block = mapLookup entry_id m

    dfs :: LabelSet -> [CmmBlock] -> [CmmBlock]
    dfs _ [] = []
    dfs visited (block:bs)
      | id `setMember` visited = dfs visited bs
      | otherwise              = block : dfs (setInsert id visited) bs'
      where id = entryLabel block
            bs' = foldr add_id bs (successors block)
            add_id id bs = case mapLookup id m of
                              Just b  -> b : bs
                              Nothing -> bs