inlineBoringOk :: CoreExpr -> Bool
-- See Note [INLINE for small functions]
-- True => the result of inlining the expression is
--         no bigger than the expression itself
--     eg      (\x y -> f y x)
-- This is a quick and dirty version. It doesn't attempt
-- to deal with  (\x y z -> x (y z))
-- The really important one is (x `cast` c)
inlineBoringOk e
  = go 0 e
  where
    go :: Int -> CoreExpr -> Bool
    go credit (Lam x e) | isId x           = go (credit+1) e
                        | otherwise        = go credit e
    go credit (App f (Type {}))            = go credit f
    go credit (App f a) | credit > 0
                        , exprIsTrivial a  = go (credit-1) f
    go credit (Tick _ e)                 = go credit e -- dubious
    go credit (Cast e _)                   = go credit e
    go _      (Var {})                     = boringCxtOk
    go _      _                            = boringCxtNotOk
inlineBoringOk :: CoreExpr -> Bool
inlineBoringOk e
  = go 0 e
  where
    go :: Int -> CoreExpr -> Bool
    go credit (Lam x e) | isId x           = go (credit+1) e
                        | otherwise        = go credit e
    go credit (App f (Type {}))            = go credit f
    go credit (App f a) | credit > 0
                        , exprIsTrivial a  = go (credit-1) f
    go credit (Tick _ e)                 = go credit e -- dubious
    go credit (Cast e _)                   = go credit e
    go _      (Var {})                     = boringCxtOk
    go _      _                            = boringCxtNotOk
inlineBoringOk e
  = go 0 e
  where
    go :: Int -> CoreExpr -> Bool
    go credit (Lam x e) | isId x           = go (credit+1) e
                        | otherwise        = go credit e
    go credit (App f (Type {}))            = go credit f
    go credit (App f a) | credit > 0
                        , exprIsTrivial a  = go (credit-1) f
    go credit (Tick _ e)                 = go credit e -- dubious
    go credit (Cast e _)                   = go credit e
    go _      (Var {})                     = boringCxtOk
    go _      _                            = boringCxtNotOk