    {-
    ToDo [Oct 2013]
    ~~~~~~~~~~~~~~~
    1. Nuke ForceSpecConstr for good (it is subsumed by GHC.Types.SPEC in ghc-prim)
    2. Nuke NoSpecConstr

    (c) The GRASP/AQUA Project, Glasgow University, 1992-1998

    \section[SpecConstr]{Specialise over constructors}
    -}

    {-# LANGUAGE CPP #-}

    {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}

    module GHC.Core.Opt.SpecConstr(
            specConstrProgram,
            SpecConstrAnnotation(..)
        ) where

    #include "HsVersions.h"

    import GHC.Prelude

    import GHC.Core
    import GHC.Core.Subst
    import GHC.Core.Utils
    import GHC.Core.Unfold
    import GHC.Core.FVs     ( exprsFreeVarsList )
    import GHC.Core.Opt.Monad
    import GHC.Types.Literal ( litIsLifted )
    import GHC.Unit.Module.ModGuts
    import GHC.Core.Opt.WorkWrap.Utils ( isWorkerSmallEnough, mkWorkerArgs )
    import GHC.Core.DataCon
    import GHC.Core.Coercion hiding( substCo )
    import GHC.Core.Rules
    import GHC.Core.Type     hiding ( substTy )
    import GHC.Core.TyCon   (TyCon, tyConUnique, tyConName )
    import GHC.Core.Multiplicity
    import GHC.Types.Id
    import GHC.Core.Ppr     ( pprParendExpr )
    import GHC.Core.Make    ( mkImpossibleExpr )
    import GHC.Types.Var.Env
    import GHC.Types.Var.Set
    import GHC.Types.Name
    import GHC.Types.Tickish
    import GHC.Types.Basic
    import GHC.Driver.Session ( DynFlags(..), GeneralFlag( Opt_SpecConstrKeen )
                              , gopt, hasPprDebug )
    import GHC.Driver.Ppr
    import GHC.Data.Maybe     ( orElse, catMaybes, isJust, isNothing )
    import GHC.Types.Demand
    import GHC.Types.Cpr
    import GHC.Serialized   ( deserializeWithData )
    import GHC.Utils.Misc
    import GHC.Data.Pair
    import GHC.Types.Unique.Supply
    import GHC.Utils.Outputable
    import GHC.Utils.Panic
    import GHC.Data.FastString
    import GHC.Types.Unique.FM
    import GHC.Utils.Monad
    import Control.Monad    ( zipWithM )
    import Data.List (nubBy, sortBy, partition)
    import GHC.Builtin.Names ( specTyConKey )
    import GHC.Unit.Module
    import GHC.Exts( SpecConstrAnnotation(..) )
    import Data.Ord( comparing )

    {-
    -----------------------------------------------------
                            Game plan
    -----------------------------------------------------

    Consider
            drop n []     = []
            drop 0 xs     = []
            drop n (x:xs) = drop (n-1) xs

    After the first time round, we could pass n unboxed.  This happens in
    numerical code too.  Here's what it looks like in Core:

            drop n xs = case xs of
                          []     -> []
                          (y:ys) -> case n of
                                      I# n# -> case n# of
                                                 0 -> []
                                                 _ -> drop (I# (n# -# 1#)) xs

    Notice that the recursive call has an explicit constructor as argument.
    Noticing this, we can make a specialised version of drop

            RULE: drop (I# n#) xs ==> drop' n# xs

            drop' n# xs = let n = I# n# in ...orig RHS...

    Now the simplifier will apply the specialisation in the rhs of drop', giving

            drop' n# xs = case xs of
                          []     -> []
                          (y:ys) -> case n# of
                                      0 -> []
                                      _ -> drop' (n# -# 1#) xs

    Much better!

    We'd also like to catch cases where a parameter is carried along unchanged,
    but evaluated each time round the loop:

            f i n = if i>0 || i>n then i else f (i*2) n

    Here f isn't strict in n, but we'd like to avoid evaluating it each iteration.
    In Core, by the time we've w/wd (f is strict in i) we get

            f i# n = case i# ># 0 of
                       False -> I# i#
                       True  -> case n of { I# n# ->
                                case i# ># n# of
                                    False -> I# i#
                                    True  -> f (i# *# 2#) n

    At the call to f, we see that the argument, n is known to be (I# n#),
    and n is evaluated elsewhere in the body of f, so we can play the same
    trick as above.

    Note [Reboxing]
    ~~~~~~~~~~~~~~~
    We must be careful not to allocate the same constructor twice.  Consider
            f p = (...(case p of (a,b) -> e)...p...,
                   ...let t = (r,s) in ...t...(f t)...)
    At the recursive call to f, we can see that t is a pair.  But we do NOT want
    to make a specialised copy:
            f' a b = let p = (a,b) in (..., ...)
    because now t is allocated by the caller, then r and s are passed to the
    recursive call, which allocates the (r,s) pair again.

    This happens if
      (a) the argument p is used in other than a case-scrutinisation way.
      (b) the argument to the call is not a 'fresh' tuple; you have to
            look into its unfolding to see that it's a tuple

    Hence the "OR" part of Note [Good arguments] below.

    ALTERNATIVE 2: pass both boxed and unboxed versions.  This no longer saves
    allocation, but does perhaps save evals. In the RULE we'd have
    something like

      f (I# x#) = f' (I# x#) x#

    If at the call site the (I# x) was an unfolding, then we'd have to
    rely on CSE to eliminate the duplicate allocation.... This alternative
    doesn't look attractive enough to pursue.

    ALTERNATIVE 3: ignore the reboxing problem.  The trouble is that
    the conservative reboxing story prevents many useful functions from being
    specialised.  Example:
            foo :: Maybe Int -> Int -> Int
            foo   (Just m) 0 = 0
            foo x@(Just m) n = foo x (n-m)
    Here the use of 'x' will clearly not require boxing in the specialised function.

    The strictness analyser has the same problem, in fact.  Example:
            f p@(a,b) = ...
    If we pass just 'a' and 'b' to the worker, it might need to rebox the
    pair to create (a,b).  A more sophisticated analysis might figure out
    precisely the cases in which this could happen, but the strictness
    analyser does no such analysis; it just passes 'a' and 'b', and hopes
    for the best.

    So my current choice is to make SpecConstr similarly aggressive, and
    ignore the bad potential of reboxing.

    Note [Good arguments]
    ~~~~~~~~~~~~~~~~~~~~~
    So we look for

    * A self-recursive function.  Ignore mutual recursion for now,
      because it's less common, and the code is simpler for self-recursion.

    * EITHER

       a) At a recursive call, one or more parameters is an explicit
          constructor application
            AND
          That same parameter is scrutinised by a case somewhere in
          the RHS of the function

      OR

        b) At a recursive call, one or more parameters has an unfolding
           that is an explicit constructor application
            AND
          That same parameter is scrutinised by a case somewhere in
          the RHS of the function
            AND
          Those are the only uses of the parameter (see Note [Reboxing])

    What to abstract over
    ~~~~~~~~~~~~~~~~~~~~~
    There's a bit of a complication with type arguments.  If the call
    site looks like

            f p = ...f ((:) [a] x xs)...

    then our specialised function look like

            f_spec x xs = let p = (:) [a] x xs in ....as before....

    This only makes sense if either
      a) the type variable 'a' is in scope at the top of f, or
      b) the type variable 'a' is an argument to f (and hence fs)

    Actually, (a) may hold for value arguments too, in which case
    we may not want to pass them.  Suppose 'x' is in scope at f's
    defn, but xs is not.  Then we'd like

            f_spec xs = let p = (:) [a] x xs in ....as before....

    Similarly (b) may hold too.  If x is already an argument at the
    call, no need to pass it again.

    Finally, if 'a' is not in scope at the call site, we could abstract
    it as we do the term variables:

            f_spec a x xs = let p = (:) [a] x xs in ...as before...

    So the grand plan is:

            * abstract the call site to a constructor-only pattern
              e.g.  C x (D (f p) (g q))  ==>  C s1 (D s2 s3)

            * Find the free variables of the abstracted pattern

            * Pass these variables, less any that are in scope at
              the fn defn.  But see Note [Shadowing] below.

    NOTICE that we only abstract over variables that are not in scope,
    so we're in no danger of shadowing variables used in "higher up"
    in f_spec's RHS.

    Note [Shadowing]
    ~~~~~~~~~~~~~~~~
    In this pass we gather up usage information that may mention variables
    that are bound between the usage site and the definition site; or (more
    seriously) may be bound to something different at the definition site.
    For example:

            f x = letrec g y v = let x = ...
                                 in ...(g (a,b) x)...

    Since 'x' is in scope at the call site, we may make a rewrite rule that
    looks like
            RULE forall a,b. g (a,b) x = ...
    But this rule will never match, because it's really a different 'x' at
    the call site -- and that difference will be manifest by the time the
    simplifier gets to it.  [A worry: the simplifier doesn't *guarantee*
    no-shadowing, so perhaps it may not be distinct?]

    Anyway, the rule isn't actually wrong, it's just not useful.  One possibility
    is to run deShadowBinds before running SpecConstr, but instead we run the
    simplifier.  That gives the simplest possible program for SpecConstr to
    chew on; and it virtually guarantees no shadowing.

    Note [Specialising for constant parameters]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    This one is about specialising on a *constant* (but not necessarily
    constructor) argument

        foo :: Int -> (Int -> Int) -> Int
        foo 0 f = 0
        foo m f = foo (f m) (+1)

    It produces

        lvl_rmV :: GHC.Base.Int -> GHC.Base.Int
        lvl_rmV =
          \ (ds_dlk :: GHC.Base.Int) ->
            case ds_dlk of wild_alH { GHC.Base.I# x_alG ->
            GHC.Base.I# (GHC.Prim.+# x_alG 1)

        T.$wfoo :: GHC.Prim.Int# -> (GHC.Base.Int -> GHC.Base.Int) ->
        GHC.Prim.Int#
        T.$wfoo =
          \ (ww_sme :: GHC.Prim.Int#) (w_smg :: GHC.Base.Int -> GHC.Base.Int) ->
            case ww_sme of ds_Xlw {
              __DEFAULT ->
            case w_smg (GHC.Base.I# ds_Xlw) of w1_Xmo { GHC.Base.I# ww1_Xmz ->
            T.$wfoo ww1_Xmz lvl_rmV
            };
              0 -> 0
            }

    The recursive call has lvl_rmV as its argument, so we could create a specialised copy
    with that argument baked in; that is, not passed at all.   Now it can perhaps be inlined.

    When is this worth it?  Call the constant 'lvl'
    - If 'lvl' has an unfolding that is a constructor, see if the corresponding
      parameter is scrutinised anywhere in the body.

    - If 'lvl' has an unfolding that is a inlinable function, see if the corresponding
      parameter is applied (...to enough arguments...?)

      Also do this is if the function has RULES?

    Also

    Note [Specialising for lambda parameters]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        foo :: Int -> (Int -> Int) -> Int
        foo 0 f = 0
        foo m f = foo (f m) (\n -> n-m)

    This is subtly different from the previous one in that we get an
    explicit lambda as the argument:

        T.$wfoo :: GHC.Prim.Int# -> (GHC.Base.Int -> GHC.Base.Int) ->
        GHC.Prim.Int#
        T.$wfoo =
          \ (ww_sm8 :: GHC.Prim.Int#) (w_sma :: GHC.Base.Int -> GHC.Base.Int) ->
            case ww_sm8 of ds_Xlr {
              __DEFAULT ->
            case w_sma (GHC.Base.I# ds_Xlr) of w1_Xmf { GHC.Base.I# ww1_Xmq ->
            T.$wfoo
              ww1_Xmq
              (\ (n_ad3 :: GHC.Base.Int) ->
                 case n_ad3 of wild_alB { GHC.Base.I# x_alA ->
                 GHC.Base.I# (GHC.Prim.-# x_alA ds_Xlr)
                 })
            };
              0 -> 0
            }

    I wonder if SpecConstr couldn't be extended to handle this? After all,
    lambda is a sort of constructor for functions and perhaps it already
    has most of the necessary machinery?

    Furthermore, there's an immediate win, because you don't need to allocate the lambda
    at the call site; and if perchance it's called in the recursive call, then you
    may avoid allocating it altogether.  Just like for constructors.

    Looks cool, but probably rare...but it might be easy to implement.

    Note [SpecConstr for casts]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider
        data family T a :: *
        data instance T Int = T Int

        foo n = ...
           where
             go (T 0) = 0
             go (T n) = go (T (n-1))

    The recursive call ends up looking like
            go (T (I# ...) `cast` g)
    So we want to spot the constructor application inside the cast.
    That's why we have the Cast case in argToPat

    Note [Local recursive groups]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    For a *local* recursive group, we can see all the calls to the
    function, so we seed the specialisation loop from the calls in the
    body, not from the calls in the RHS.  Consider:

      bar m n = foo n (n,n) (n,n) (n,n) (n,n)
       where
         foo n p q r s
           | n == 0    = m
           | n > 3000  = case p of { (p1,p2) -> foo (n-1) (p2,p1) q r s }
           | n > 2000  = case q of { (q1,q2) -> foo (n-1) p (q2,q1) r s }
           | n > 1000  = case r of { (r1,r2) -> foo (n-1) p q (r2,r1) s }
           | otherwise = case s of { (s1,s2) -> foo (n-1) p q r (s2,s1) }

    If we start with the RHSs of 'foo', we get lots and lots of specialisations,
    most of which are not needed.  But if we start with the (single) call
    in the rhs of 'bar' we get exactly one fully-specialised copy, and all
    the recursive calls go to this fully-specialised copy. Indeed, the original
    function is later collected as dead code.  This is very important in
    specialising the loops arising from stream fusion, for example in NDP where
    we were getting literally hundreds of (mostly unused) specialisations of
    a local function.

    In a case like the above we end up never calling the original un-specialised
    function.  (Although we still leave its code around just in case.)

    However, if we find any boring calls in the body, including *unsaturated*
    ones, such as
          letrec foo x y = ....foo...
          in map foo xs
    then we will end up calling the un-specialised function, so then we *should*
    use the calls in the un-specialised RHS as seeds.  We call these
    "boring call patterns", and callsToPats reports if it finds any of these.

    Note [Seeding top-level recursive groups]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    This seeding is done in the binding for seed_calls in specRec.

    1. If all the bindings in a top-level recursive group are local (not
       exported), then all the calls are in the rest of the top-level
       bindings.  This means we can specialise with those call patterns
       ONLY, and NOT with the RHSs of the recursive group (exactly like
       Note [Local recursive groups])

    2. But if any of the bindings are exported, the function may be called
       with any old arguments, so (for lack of anything better) we specialise
       based on
         (a) the call patterns in the RHS
         (b) the call patterns in the rest of the top-level bindings
       NB: before Apr 15 we used (a) only, but Dimitrios had an example
           where (b) was crucial, so I added that.
           Adding (b) also improved nofib allocation results:
                      multiplier: 4%   better
                      minimax:    2.8% better

    Actually in case (2), instead of using the calls from the RHS, it
    would be better to specialise in the importing module.  We'd need to
    add an INLINABLE pragma to the function, and then it can be
    specialised in the importing scope, just as is done for type classes
    in GHC.Core.Opt.Specialise.specImports. This remains to be done (#10346).

    Note [Top-level recursive groups]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    To get the call usage information from "the rest of the top level
    bindings" (c.f. Note [Seeding top-level recursive groups]), we work
    backwards through the top-level bindings so we see the usage before we
    get to the binding of the function.  Before we can collect the usage
    though, we go through all the bindings and add them to the
    environment. This is necessary because usage is only tracked for
    functions in the environment.  These two passes are called
       'go' and 'goEnv'
    in specConstrProgram.  (Looks a bit revolting to me.)

    Note [Do not specialise diverging functions]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Specialising a function that just diverges is a waste of code.
    Furthermore, it broke GHC (simpl014) thus:
       {-# STR Sb #-}
       f = \x. case x of (a,b) -> f x
    If we specialise f we get
       f = \x. case x of (a,b) -> fspec a b
    But fspec doesn't have decent strictness info.  As it happened,
    (f x) :: IO t, so the state hack applied and we eta expanded fspec,
    and hence f.  But now f's strictness is less than its arity, which
    breaks an invariant.

    Note [Forcing specialisation]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    With stream fusion and in other similar cases, we want to fully
    specialise some (but not necessarily all!) loops regardless of their
    size and the number of specialisations.

    We allow a library to do this, in one of two ways (one which is
    deprecated):

      1) Add a parameter of type GHC.Types.SPEC (from ghc-prim) to the loop body.

      2) (Deprecated) Annotate a type with ForceSpecConstr from GHC.Exts,
         and then add *that* type as a parameter to the loop body

    The reason #2 is deprecated is because it requires GHCi, which isn't
    available for things like a cross compiler using stage1.

    Here's a (simplified) example from the `vector` package. You may bring
    the special 'force specialization' type into scope by saying:

      import GHC.Types (SPEC(..))

    or by defining your own type (again, deprecated):

      data SPEC = SPEC | SPEC2
      {-# ANN type SPEC ForceSpecConstr #-}

    (Note this is the exact same definition of GHC.Types.SPEC, just
    without the annotation.)

    After that, you say:

      foldl :: (a -> b -> a) -> a -> Stream b -> a
      {-# INLINE foldl #-}
      foldl f z (Stream step s _) = foldl_loop SPEC z s
        where
          foldl_loop !sPEC z s = case step s of
                                  Yield x s' -> foldl_loop sPEC (f z x) s'
                                  Skip       -> foldl_loop sPEC z s'
                                  Done       -> z

    SpecConstr will spot the SPEC parameter and always fully specialise
    foldl_loop. Note that

      * We have to prevent the SPEC argument from being removed by
        w/w which is why (a) SPEC is a sum type, and (b) we have to seq on
        the SPEC argument.

      * And lastly, the SPEC argument is ultimately eliminated by
        SpecConstr itself so there is no runtime overhead.

    This is all quite ugly; we ought to come up with a better design.

    ForceSpecConstr arguments are spotted in scExpr' and scTopBinds which then set
    sc_force to True when calling specLoop. This flag does four things:

      * Ignore specConstrThreshold, to specialise functions of arbitrary size
            (see scTopBind)
      * Ignore specConstrCount, to make arbitrary numbers of specialisations
            (see specialise)
      * Specialise even for arguments that are not scrutinised in the loop
            (see argToPat; #4448)
      * Only specialise on recursive types a finite number of times
            (see is_too_recursive; #5550; Note [Limit recursive specialisation])

    The flag holds only for specialising a single binding group, and NOT
    for nested bindings.  (So really it should be passed around explicitly
    and not stored in ScEnv.)  #14379 turned out to be caused by
       f SPEC x = let g1 x = ...
                  in ...
    We force-specialise f (because of the SPEC), but that generates a specialised
    copy of g1 (as well as the original).  Alas g1 has a nested binding g2; and
    in each copy of g1 we get an unspecialised and specialised copy of g2; and so
    on. Result, exponential.  So the force-spec flag now only applies to one
    level of bindings at a time.

    Mechanism for this one-level-only thing:

     - Switch it on at the call to specRec, in scExpr and scTopBinds
     - Switch it off when doing the RHSs;
       this can be done very conveniently in decreaseSpecCount

    What alternatives did I consider?

    * Annotating the loop itself doesn't work because (a) it is local and
      (b) it will be w/w'ed and having w/w propagating annotations somehow
      doesn't seem like a good idea. The types of the loop arguments
      really seem to be the most persistent thing.

    * Annotating the types that make up the loop state doesn't work,
      either, because (a) it would prevent us from using types like Either
      or tuples here, (b) we don't want to restrict the set of types that
      can be used in Stream states and (c) some types are fixed by the
      user (e.g., the accumulator here) but we still want to specialise as
      much as possible.

    Alternatives to ForceSpecConstr
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Instead of giving the loop an extra argument of type SPEC, we
    also considered *wrapping* arguments in SPEC, thus
      data SPEC a = SPEC a | SPEC2

      loop = \arg -> case arg of
                         SPEC state ->
                            case state of (x,y) -> ... loop (SPEC (x',y')) ...
                            S2 -> error ...
    The idea is that a SPEC argument says "specialise this argument
    regardless of whether the function case-analyses it".  But this
    doesn't work well:
      * SPEC must still be a sum type, else the strictness analyser
        eliminates it
      * But that means that 'loop' won't be strict in its real payload
    This loss of strictness in turn screws up specialisation, because
    we may end up with calls like
       loop (SPEC (case z of (p,q) -> (q,p)))
    Without the SPEC, if 'loop' were strict, the case would move out
    and we'd see loop applied to a pair. But if 'loop' isn't strict
    this doesn't look like a specialisable call.

    Note [Limit recursive specialisation]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    It is possible for ForceSpecConstr to cause an infinite loop of specialisation.
    Because there is no limit on the number of specialisations, a recursive call with
    a recursive constructor as an argument (for example, list cons) will generate
    a specialisation for that constructor. If the resulting specialisation also
    contains a recursive call with the constructor, this could proceed indefinitely.

    For example, if ForceSpecConstr is on:
      loop :: [Int] -> [Int] -> [Int]
      loop z []         = z
      loop z (x:xs)     = loop (x:z) xs
    this example will create a specialisation for the pattern
      loop (a:b) c      = loop' a b c

      loop' a b []      = (a:b)
      loop' a b (x:xs)  = loop (x:(a:b)) xs
    and a new pattern is found:
      loop (a:(b:c)) d  = loop'' a b c d
    which can continue indefinitely.

    Roman's suggestion to fix this was to stop after a couple of times on recursive types,
    but still specialising on non-recursive types as much as possible.

    To implement this, we count the number of times we have gone round the
    "specialise recursively" loop ('go' in 'specRec').  Once have gone round
    more than N times (controlled by -fspec-constr-recursive=N) we check

      - If sc_force is off, and sc_count is (Just max) then we don't
        need to do anything: trim_pats will limit the number of specs

      - Otherwise check if any function has now got more than (sc_count env)
        specialisations.  If sc_count is "no limit" then we arbitrarily
        choose 10 as the limit (ugh).

    See #5550.   Also #13623, where this test had become over-aggressive,
    and we lost a wonderful specialisation that we really wanted!

    Note [NoSpecConstr]
    ~~~~~~~~~~~~~~~~~~~
    The ignoreDataCon stuff allows you to say
        {-# ANN type T NoSpecConstr #-}
    to mean "don't specialise on arguments of this type".  It was added
    before we had ForceSpecConstr.  Lacking ForceSpecConstr we specialised
    regardless of size; and then we needed a way to turn that *off*.  Now
    that we have ForceSpecConstr, this NoSpecConstr is probably redundant.
    (Used only for PArray, TODO: remove?)

    -----------------------------------------------------
                    Stuff not yet handled
    -----------------------------------------------------

    Here are notes arising from Roman's work that I don't want to lose.

    Example 1
    ~~~~~~~~~
        data T a = T !a

        foo :: Int -> T Int -> Int
        foo 0 t = 0
        foo x t | even x    = case t of { T n -> foo (x-n) t }
                | otherwise = foo (x-1) t

    SpecConstr does no specialisation, because the second recursive call
    looks like a boxed use of the argument.  A pity.

        $wfoo_sFw :: GHC.Prim.Int# -> T.T GHC.Base.Int -> GHC.Prim.Int#
        $wfoo_sFw =
          \ (ww_sFo [Just L] :: GHC.Prim.Int#) (w_sFq [Just L] :: T.T GHC.Base.Int) ->
             case ww_sFo of ds_Xw6 [Just L] {
               __DEFAULT ->
                    case GHC.Prim.remInt# ds_Xw6 2 of wild1_aEF [Dead Just A] {
                      __DEFAULT -> $wfoo_sFw (GHC.Prim.-# ds_Xw6 1) w_sFq;
                      0 ->
                        case w_sFq of wild_Xy [Just L] { T.T n_ad5 [Just U(L)] ->
                        case n_ad5 of wild1_aET [Just A] { GHC.Base.I# y_aES [Just L] ->
                        $wfoo_sFw (GHC.Prim.-# ds_Xw6 y_aES) wild_Xy
                        } } };
               0 -> 0

    Example 2
    ~~~~~~~~~
        data a :*: b = !a :*: !b
        data T a = T !a

        foo :: (Int :*: T Int) -> Int
        foo (0 :*: t) = 0
        foo (x :*: t) | even x    = case t of { T n -> foo ((x-n) :*: t) }
                      | otherwise = foo ((x-1) :*: t)

    Very similar to the previous one, except that the parameters are now in
    a strict tuple. Before SpecConstr, we have

        $wfoo_sG3 :: GHC.Prim.Int# -> T.T GHC.Base.Int -> GHC.Prim.Int#
        $wfoo_sG3 =
          \ (ww_sFU [Just L] :: GHC.Prim.Int#) (ww_sFW [Just L] :: T.T
        GHC.Base.Int) ->
            case ww_sFU of ds_Xws [Just L] {
              __DEFAULT ->
            case GHC.Prim.remInt# ds_Xws 2 of wild1_aEZ [Dead Just A] {
              __DEFAULT ->
                case ww_sFW of tpl_B2 [Just L] { T.T a_sFo [Just A] ->
                $wfoo_sG3 (GHC.Prim.-# ds_Xws 1) tpl_B2             -- $wfoo1
                };
              0 ->
                case ww_sFW of wild_XB [Just A] { T.T n_ad7 [Just S(L)] ->
                case n_ad7 of wild1_aFd [Just L] { GHC.Base.I# y_aFc [Just L] ->
                $wfoo_sG3 (GHC.Prim.-# ds_Xws y_aFc) wild_XB        -- $wfoo2
                } } };
              0 -> 0 }

    We get two specialisations:
    "SC:$wfoo1" [0] __forall {a_sFB :: GHC.Base.Int sc_sGC :: GHC.Prim.Int#}
                      Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int a_sFB)
                      = Foo.$s$wfoo1 a_sFB sc_sGC ;
    "SC:$wfoo2" [0] __forall {y_aFp :: GHC.Prim.Int# sc_sGC :: GHC.Prim.Int#}
                      Foo.$wfoo sc_sGC (Foo.T @ GHC.Base.Int (GHC.Base.I# y_aFp))
                      = Foo.$s$wfoo y_aFp sc_sGC ;

    But perhaps the first one isn't good.  After all, we know that tpl_B2 is
    a T (I# x) really, because T is strict and Int has one constructor.  (We can't
    unbox the strict fields, because T is polymorphic!)

    ************************************************************************
    *                                                                      *
    \subsection{Top level wrapper stuff}
    *                                                                      *
    ************************************************************************
    -}

    specConstrProgram :: ModGuts -> CoreM ModGuts
    specConstrProgram :: ModGuts -> CoreM ModGuts
    specConstrProgram ModGuts
    guts
      = do
          DynFlags
    dflags <- forall (m :: * -> *). HasDynFlags m => m DynFlags
    getDynFlags
          UniqSupply
    us     <- forall (m :: * -> *). MonadUnique m => m UniqSupply
    getUniqueSupplyM
          (ModuleEnv SpecConstrAnnotation
    _, NameEnv SpecConstrAnnotation
    annos) <- forall a.
    Typeable a =>
    ([Word8] -> a) -> ModGuts -> CoreM (ModuleEnv a, NameEnv a)
    getFirstAnnotations forall a. Data a => [Word8] -> a
    deserializeWithData ModGuts
    guts
          Module
    this_mod <- forall (m :: * -> *). HasModule m => m Module
    getModule
          let binds' :: [CoreBind]
    binds' = forall a. [a] -> [a]
    reverse forall a b. (a -> b) -> a -> b
    $ forall a b. (a, b) -> a
    fst forall a b. (a -> b) -> a -> b
    $ forall a. UniqSupply -> UniqSM a -> (a, UniqSupply)
    initUs UniqSupply
    us forall a b. (a -> b) -> a -> b
    $ do
                        -- Note [Top-level recursive groups]
                        (ScEnv
    env, [CoreBind]
    binds) <- ScEnv -> [CoreBind] -> UniqSM (ScEnv, [CoreBind])
    goEnv (DynFlags -> Module -> NameEnv SpecConstrAnnotation -> ScEnv
    initScEnv DynFlags
    dflags Module
    this_mod NameEnv SpecConstrAnnotation
    annos)
                                              (ModGuts -> [CoreBind]
    mg_binds ModGuts
    guts)
                            -- binds is identical to (mg_binds guts), except that the
                            -- binders on the LHS have been replaced by extendBndr
                            --   (SPJ this seems like overkill; I don't think the binders
                            --    will change at all; and we don't substitute in the RHSs anyway!!)
                        ScEnv -> ScUsage -> [CoreBind] -> UniqSM [CoreBind]
    go ScEnv
    env ScUsage
    nullUsage (forall a. [a] -> [a]
    reverse [CoreBind]
    binds)

          forall (m :: * -> *) a. Monad m => a -> m a
    return (ModGuts
    guts { mg_binds :: [CoreBind]
    mg_binds = [CoreBind]
    binds' })
      where
        -- See Note [Top-level recursive groups]
        goEnv :: ScEnv -> [CoreBind] -> UniqSM (ScEnv, [CoreBind])
    goEnv ScEnv
    env []            = forall (m :: * -> *) a. Monad m => a -> m a
    return (ScEnv
    env, [])
        goEnv ScEnv
    env (CoreBind
    bind:[CoreBind]
    binds)  = do (ScEnv
    env', CoreBind
    bind')   <- ScEnv -> CoreBind -> UniqSM (ScEnv, CoreBind)
    scTopBindEnv ScEnv
    env CoreBind
    bind
                                     (ScEnv
    env'', [CoreBind]
    binds') <- ScEnv -> [CoreBind] -> UniqSM (ScEnv, [CoreBind])
    goEnv ScEnv
    env' [CoreBind]
    binds
                                     forall (m :: * -> *) a. Monad m => a -> m a
    return (ScEnv
    env'', CoreBind
    bind' forall a. a -> [a] -> [a]
    : [CoreBind]
    binds')

        -- Arg list of bindings is in reverse order
        go :: ScEnv -> ScUsage -> [CoreBind] -> UniqSM [CoreBind]
    go ScEnv
    _   ScUsage
    _   []           = forall (m :: * -> *) a. Monad m => a -> m a
    return []
        go ScEnv
    env ScUsage
    usg (CoreBind
    bind:[CoreBind]
    binds) = do (ScUsage
    usg', CoreBind
    bind') <- ScEnv -> ScUsage -> CoreBind -> UniqSM (ScUsage, CoreBind)
    scTopBind ScEnv
    env ScUsage
    usg CoreBind
    bind
                                     [CoreBind]
    binds' <- ScEnv -> ScUsage -> [CoreBind] -> UniqSM [CoreBind]
    go ScEnv
    env ScUsage
    usg' [CoreBind]
    binds
                                     forall (m :: * -> *) a. Monad m => a -> m a
    return (CoreBind
    bind' forall a. a -> [a] -> [a]
    : [CoreBind]
    binds')

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Environment: goes downwards}
    *                                                                      *
    ************************************************************************

    Note [Work-free values only in environment]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The sc_vals field keeps track of in-scope value bindings, so
    that if we come across (case x of Just y ->...) we can reduce the
    case from knowing that x is bound to a pair.

    But only *work-free* values are ok here. For example if the envt had
        x -> Just (expensive v)
    then we do NOT want to expand to
         let y = expensive v in ...
    because the x-binding still exists and we've now duplicated (expensive v).

    This seldom happens because let-bound constructor applications are
    ANF-ised, but it can happen as a result of on-the-fly transformations in
    SpecConstr itself.  Here is #7865:

            let {
              a'_shr =
                case xs_af8 of _ {
                  [] -> acc_af6;
                  : ds_dgt [Dmd=<L,A>] ds_dgu [Dmd=<L,A>] ->
                    (expensive x_af7, x_af7
                } } in
            let {
              ds_sht =
                case a'_shr of _ { (p'_afd, q'_afe) ->
                TSpecConstr_DoubleInline.recursive
                  (GHC.Types.: @ GHC.Types.Int x_af7 wild_X6) (q'_afe, p'_afd)
                } } in

    When processed knowing that xs_af8 was bound to a cons, we simplify to
       a'_shr = (expensive x_af7, x_af7)
    and we do NOT want to inline that at the occurrence of a'_shr in ds_sht.
    (There are other occurrences of a'_shr.)  No no no.

    It would be possible to do some on-the-fly ANF-ising, so that a'_shr turned
    into a work-free value again, thus
       a1 = expensive x_af7
       a'_shr = (a1, x_af7)
    but that's more work, so until its shown to be important I'm going to
    leave it for now.

    Note [Making SpecConstr keener]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider this, in (perf/should_run/T9339)
       last (filter odd [1..1000])

    After optimisation, including SpecConstr, we get:
       f :: Int# -> Int -> Int
       f x y = case remInt# x 2# of
                 __DEFAULT -> case x of
                                __DEFAULT -> f (+# wild_Xp 1#) (I# x)
                                1000000# -> ...
                 0# -> case x of
                         __DEFAULT -> f (+# wild_Xp 1#) y
                        1000000#   -> y

    Not good!  We build an (I# x) box every time around the loop.
    SpecConstr (as described in the paper) does not specialise f, despite
    the call (f ... (I# x)) because 'y' is not scrutinised in the body.
    But it is much better to specialise f for the case where the argument
    is of form (I# x); then we build the box only when returning y, which
    is on the cold path.

    Another example:

       f x = ...(g x)....

    Here 'x' is not scrutinised in f's body; but if we did specialise 'f'
    then the call (g x) might allow 'g' to be specialised in turn.

    So sc_keen controls whether or not we take account of whether argument is
    scrutinised in the body.  True <=> ignore that, and specialise whenever
    the function is applied to a data constructor.
    -}

    data ScEnv = SCE { ScEnv -> DynFlags
    sc_dflags    :: DynFlags,
                       ScEnv -> UnfoldingOpts
    sc_uf_opts   :: !UnfoldingOpts, -- ^ Unfolding options
                       ScEnv -> Module
    sc_module    :: !Module,
                       ScEnv -> Maybe Int
    sc_size      :: Maybe Int,   -- Size threshold
                                                    -- Nothing => no limit

                       ScEnv -> Maybe Int
    sc_count     :: Maybe Int,   -- Max # of specialisations for any one fn
                                                    -- Nothing => no limit
                                                    -- See Note [Avoiding exponential blowup]

                       ScEnv -> Int
    sc_recursive :: Int,         -- Max # of specialisations over recursive type.
                                                    -- Stops ForceSpecConstr from diverging.

                       ScEnv -> Bool
    sc_keen     :: Bool,         -- Specialise on arguments that are known
                                                    -- constructors, even if they are not
                                                    -- scrutinised in the body.  See
                                                    -- Note [Making SpecConstr keener]

                       ScEnv -> Bool
    sc_force     :: Bool,        -- Force specialisation?
                                                    -- See Note [Forcing specialisation]

                       ScEnv -> Subst
    sc_subst     :: Subst,       -- Current substitution
                                                    -- Maps InIds to OutExprs

                       ScEnv -> HowBoundEnv
    sc_how_bound :: HowBoundEnv,
                            -- Binds interesting non-top-level variables
                            -- Domain is OutVars (*after* applying the substitution)

                       ScEnv -> ValueEnv
    sc_vals      :: ValueEnv,
                            -- Domain is OutIds (*after* applying the substitution)
                            -- Used even for top-level bindings (but not imported ones)
                            -- The range of the ValueEnv is *work-free* values
                            -- such as (\x. blah), or (Just v)
                            -- but NOT (Just (expensive v))
                            -- See Note [Work-free values only in environment]

                       ScEnv -> NameEnv SpecConstrAnnotation
    sc_annotations :: UniqFM Name SpecConstrAnnotation
                 }

    ---------------------
    type HowBoundEnv = VarEnv HowBound      -- Domain is OutVars

    ---------------------
    type ValueEnv = IdEnv Value             -- Domain is OutIds
    data Value    = ConVal AltCon [CoreArg] -- _Saturated_ constructors
                                            --   The AltCon is never DEFAULT
                  | LambdaVal               -- Inlinable lambdas or PAPs

    instance Outputable Value where
       ppr :: Value -> SDoc
    ppr (ConVal AltCon
    con [Expr Id]
    args) = forall a. Outputable a => a -> SDoc
    ppr AltCon
    con SDoc -> SDoc -> SDoc
    <+> forall a. Outputable a => [a] -> SDoc
    interpp'SP [Expr Id]
    args
       ppr Value
    LambdaVal         = String -> SDoc
    text String
    "<Lambda>"

    ---------------------
    initScEnv :: DynFlags -> Module -> UniqFM Name SpecConstrAnnotation -> ScEnv
    initScEnv :: DynFlags -> Module -> NameEnv SpecConstrAnnotation -> ScEnv
    initScEnv DynFlags
    dflags Module
    this_mod NameEnv SpecConstrAnnotation
    anns
      = SCE { sc_dflags :: DynFlags
    sc_dflags      = DynFlags
    dflags,
              sc_uf_opts :: UnfoldingOpts
    sc_uf_opts     = DynFlags -> UnfoldingOpts
    unfoldingOpts DynFlags
    dflags,
              sc_module :: Module
    sc_module      = Module
    this_mod,
              sc_size :: Maybe Int
    sc_size        = DynFlags -> Maybe Int
    specConstrThreshold DynFlags
    dflags,
              sc_count :: Maybe Int
    sc_count       = DynFlags -> Maybe Int
    specConstrCount     DynFlags
    dflags,
              sc_recursive :: Int
    sc_recursive   = DynFlags -> Int
    specConstrRecursive DynFlags
    dflags,
              sc_keen :: Bool
    sc_keen        = GeneralFlag -> DynFlags -> Bool
    gopt GeneralFlag
    Opt_SpecConstrKeen DynFlags
    dflags,
              sc_force :: Bool
    sc_force       = Bool
    False,
              sc_subst :: Subst
    sc_subst       = Subst
    emptySubst,
              sc_how_bound :: HowBoundEnv
    sc_how_bound   = forall a. VarEnv a
    emptyVarEnv,
              sc_vals :: ValueEnv
    sc_vals        = forall a. VarEnv a
    emptyVarEnv,
              sc_annotations :: NameEnv SpecConstrAnnotation
    sc_annotations = NameEnv SpecConstrAnnotation
    anns }

    data HowBound = RecFun  -- These are the recursive functions for which
                            -- we seek interesting call patterns

                  | RecArg  -- These are those functions' arguments, or their sub-components;
                            -- we gather occurrence information for these

    instance Outputable HowBound where
      ppr :: HowBound -> SDoc
    ppr HowBound
    RecFun = String -> SDoc
    text String
    "RecFun"
      ppr HowBound
    RecArg = String -> SDoc
    text String
    "RecArg"

    scForce :: ScEnv -> Bool -> ScEnv
    scForce :: ScEnv -> Bool -> ScEnv
    scForce ScEnv
    env Bool
    b = ScEnv
    env { sc_force :: Bool
    sc_force = Bool
    b }

    lookupHowBound :: ScEnv -> Id -> Maybe HowBound
    lookupHowBound :: ScEnv -> Id -> Maybe HowBound
    lookupHowBound ScEnv
    env Id
    id = forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv (ScEnv -> HowBoundEnv
    sc_how_bound ScEnv
    env) Id
    id

    scSubstId :: ScEnv -> Id -> CoreExpr
    scSubstId :: ScEnv -> Id -> Expr Id
    scSubstId ScEnv
    env Id
    v = HasDebugCallStack => Subst -> Id -> Expr Id
    lookupIdSubst (ScEnv -> Subst
    sc_subst ScEnv
    env) Id
    v

    scSubstTy :: ScEnv -> Type -> Type
    scSubstTy :: ScEnv -> Type -> Type
    scSubstTy ScEnv
    env Type
    ty = Subst -> Type -> Type
    substTy (ScEnv -> Subst
    sc_subst ScEnv
    env) Type
    ty

    scSubstCo :: ScEnv -> Coercion -> Coercion
    scSubstCo :: ScEnv -> Coercion -> Coercion
    scSubstCo ScEnv
    env Coercion
    co = HasCallStack => Subst -> Coercion -> Coercion
    substCo (ScEnv -> Subst
    sc_subst ScEnv
    env) Coercion
    co

    zapScSubst :: ScEnv -> ScEnv
    zapScSubst :: ScEnv -> ScEnv
    zapScSubst ScEnv
    env = ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst -> Subst
    zapSubstEnv (ScEnv -> Subst
    sc_subst ScEnv
    env) }

    extendScInScope :: ScEnv -> [Var] -> ScEnv
            -- Bring the quantified variables into scope
    extendScInScope :: ScEnv -> [Id] -> ScEnv
    extendScInScope ScEnv
    env [Id]
    qvars = ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst -> [Id] -> Subst
    extendInScopeList (ScEnv -> Subst
    sc_subst ScEnv
    env) [Id]
    qvars }

            -- Extend the substitution
    extendScSubst :: ScEnv -> Var -> OutExpr -> ScEnv
    extendScSubst :: ScEnv -> Id -> Expr Id -> ScEnv
    extendScSubst ScEnv
    env Id
    var Expr Id
    expr = ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst -> Id -> Expr Id -> Subst
    extendSubst (ScEnv -> Subst
    sc_subst ScEnv
    env) Id
    var Expr Id
    expr }

    extendScSubstList :: ScEnv -> [(Var,OutExpr)] -> ScEnv
    extendScSubstList :: ScEnv -> [(Id, Expr Id)] -> ScEnv
    extendScSubstList ScEnv
    env [(Id, Expr Id)]
    prs = ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst -> [(Id, Expr Id)] -> Subst
    extendSubstList (ScEnv -> Subst
    sc_subst ScEnv
    env) [(Id, Expr Id)]
    prs }

    extendHowBound :: ScEnv -> [Var] -> HowBound -> ScEnv
    extendHowBound :: ScEnv -> [Id] -> HowBound -> ScEnv
    extendHowBound ScEnv
    env [Id]
    bndrs HowBound
    how_bound
      = ScEnv
    env { sc_how_bound :: HowBoundEnv
    sc_how_bound = forall a. VarEnv a -> [(Id, a)] -> VarEnv a
    extendVarEnvList (ScEnv -> HowBoundEnv
    sc_how_bound ScEnv
    env)
                                [(Id
    bndr,HowBound
    how_bound) | Id
    bndr <- [Id]
    bndrs] }

    extendBndrsWith :: HowBound -> ScEnv -> [Var] -> (ScEnv, [Var])
    extendBndrsWith :: HowBound -> ScEnv -> [Id] -> (ScEnv, [Id])
    extendBndrsWith HowBound
    how_bound ScEnv
    env [Id]
    bndrs
      = (ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst
    subst', sc_how_bound :: HowBoundEnv
    sc_how_bound = HowBoundEnv
    hb_env' }, [Id]
    bndrs')
      where
        (Subst
    subst', [Id]
    bndrs') = Subst -> [Id] -> (Subst, [Id])
    substBndrs (ScEnv -> Subst
    sc_subst ScEnv
    env) [Id]
    bndrs
        hb_env' :: HowBoundEnv
    hb_env' = ScEnv -> HowBoundEnv
    sc_how_bound ScEnv
    env forall a. VarEnv a -> [(Id, a)] -> VarEnv a
    `extendVarEnvList`
                        [(Id
    bndr,HowBound
    how_bound) | Id
    bndr <- [Id]
    bndrs']

    extendBndrWith :: HowBound -> ScEnv -> Var -> (ScEnv, Var)
    extendBndrWith :: HowBound -> ScEnv -> Id -> (ScEnv, Id)
    extendBndrWith HowBound
    how_bound ScEnv
    env Id
    bndr
      = (ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst
    subst', sc_how_bound :: HowBoundEnv
    sc_how_bound = HowBoundEnv
    hb_env' }, Id
    bndr')
      where
        (Subst
    subst', Id
    bndr') = Subst -> Id -> (Subst, Id)
    substBndr (ScEnv -> Subst
    sc_subst ScEnv
    env) Id
    bndr
        hb_env' :: HowBoundEnv
    hb_env' = forall a. VarEnv a -> Id -> a -> VarEnv a
    extendVarEnv (ScEnv -> HowBoundEnv
    sc_how_bound ScEnv
    env) Id
    bndr' HowBound
    how_bound

    extendRecBndrs :: ScEnv -> [Var] -> (ScEnv, [Var])
    extendRecBndrs :: ScEnv -> [Id] -> (ScEnv, [Id])
    extendRecBndrs ScEnv
    env [Id]
    bndrs  = (ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst
    subst' }, [Id]
    bndrs')
                          where
                            (Subst
    subst', [Id]
    bndrs') = Subst -> [Id] -> (Subst, [Id])
    substRecBndrs (ScEnv -> Subst
    sc_subst ScEnv
    env) [Id]
    bndrs

    extendBndr :: ScEnv -> Var -> (ScEnv, Var)
    extendBndr :: ScEnv -> Id -> (ScEnv, Id)
    extendBndr  ScEnv
    env Id
    bndr  = (ScEnv
    env { sc_subst :: Subst
    sc_subst = Subst
    subst' }, Id
    bndr')
                          where
                            (Subst
    subst', Id
    bndr') = Subst -> Id -> (Subst, Id)
    substBndr (ScEnv -> Subst
    sc_subst ScEnv
    env) Id
    bndr

    extendValEnv :: ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv :: ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv ScEnv
    env Id
    _  Maybe Value
    Nothing   = ScEnv
    env
    extendValEnv ScEnv
    env Id
    id (Just Value
    cv)
     | Value -> Bool
    valueIsWorkFree Value
    cv      -- Don't duplicate work!!  #7865
     = ScEnv
    env { sc_vals :: ValueEnv
    sc_vals = forall a. VarEnv a -> Id -> a -> VarEnv a
    extendVarEnv (ScEnv -> ValueEnv
    sc_vals ScEnv
    env) Id
    id Value
    cv }
    extendValEnv ScEnv
    env Id
    _ Maybe Value
    _ = ScEnv
    env

    extendCaseBndrs :: ScEnv -> OutExpr -> OutId -> AltCon -> [Var] -> (ScEnv, [Var])
    -- When we encounter
    --      case scrut of b
    --          C x y -> ...
    -- we want to bind b, to (C x y)
    -- NB1: Extends only the sc_vals part of the envt
    -- NB2: Kill the dead-ness info on the pattern binders x,y, since
    --      they are potentially made alive by the [b -> C x y] binding
    extendCaseBndrs :: ScEnv -> Expr Id -> Id -> AltCon -> [Id] -> (ScEnv, [Id])
    extendCaseBndrs ScEnv
    env Expr Id
    scrut Id
    case_bndr AltCon
    con [Id]
    alt_bndrs
       = (ScEnv
    env2, [Id]
    alt_bndrs')
     where
       live_case_bndr :: Bool
    live_case_bndr = Bool -> Bool
    not (Id -> Bool
    isDeadBinder Id
    case_bndr)
       env1 :: ScEnv
    env1 | Var Id
    v <- forall b. (CoreTickish -> Bool) -> Expr b -> Expr b
    stripTicksTopE (forall a b. a -> b -> a
    const Bool
    True) Expr Id
    scrut
                             = ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv ScEnv
    env Id
    v Maybe Value
    cval
            | Bool
    otherwise      = ScEnv
    env  -- See Note [Add scrutinee to ValueEnv too]
       env2 :: ScEnv
    env2 | Bool
    live_case_bndr = ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv ScEnv
    env1 Id
    case_bndr Maybe Value
    cval
            | Bool
    otherwise      = ScEnv
    env1

       alt_bndrs' :: [Id]
    alt_bndrs' | case Expr Id
    scrut of { Var {} -> Bool
    True; Expr Id
    _ -> Bool
    live_case_bndr }
                  = forall a b. (a -> b) -> [a] -> [b]
    map Id -> Id
    zap [Id]
    alt_bndrs
                  | Bool
    otherwise
                  = [Id]
    alt_bndrs

       cval :: Maybe Value
    cval = case AltCon
    con of
                    AltCon
    DEFAULT    -> forall a. Maybe a
    Nothing
                    LitAlt {}  -> forall a. a -> Maybe a
    Just (AltCon -> [Expr Id] -> Value
    ConVal AltCon
    con [])
                    DataAlt {} -> forall a. a -> Maybe a
    Just (AltCon -> [Expr Id] -> Value
    ConVal AltCon
    con [Expr Id]
    vanilla_args)
                          where
                            vanilla_args :: [Expr Id]
    vanilla_args = forall a b. (a -> b) -> [a] -> [b]
    map forall b. Type -> Expr b
    Type (Type -> [Type]
    tyConAppArgs (Id -> Type
    idType Id
    case_bndr)) forall a. [a] -> [a] -> [a]
    ++
                                           forall b. [Id] -> [Expr b]
    varsToCoreExprs [Id]
    alt_bndrs

       zap :: Id -> Id
    zap Id
    v | Id -> Bool
    isTyVar Id
    v = Id
    v                -- See NB2 above
             | Bool
    otherwise = Id -> Id
    zapIdOccInfo Id
    v

    decreaseSpecCount :: ScEnv -> Int -> ScEnv
    -- See Note [Avoiding exponential blowup]
    decreaseSpecCount :: ScEnv -> Int -> ScEnv
    decreaseSpecCount ScEnv
    env Int
    n_specs
      = ScEnv
    env { sc_force :: Bool
    sc_force = Bool
    False   -- See Note [Forcing specialisation]
            , sc_count :: Maybe Int
    sc_count = case ScEnv -> Maybe Int
    sc_count ScEnv
    env of
                           Maybe Int
    Nothing -> forall a. Maybe a
    Nothing
                           Just Int
    n  -> forall a. a -> Maybe a
    Just (Int
    n forall a. Integral a => a -> a -> a
    `div` (Int
    n_specs forall a. Num a => a -> a -> a
    + Int
    1)) }
            -- The "+1" takes account of the original function;
            -- See Note [Avoiding exponential blowup]

    ---------------------------------------------------
    -- See Note [Forcing specialisation]
    ignoreType    :: ScEnv -> Type   -> Bool
    ignoreDataCon  :: ScEnv -> DataCon -> Bool
    forceSpecBndr :: ScEnv -> Var    -> Bool

    ignoreDataCon :: ScEnv -> DataCon -> Bool
    ignoreDataCon ScEnv
    env DataCon
    dc = ScEnv -> TyCon -> Bool
    ignoreTyCon ScEnv
    env (DataCon -> TyCon
    dataConTyCon DataCon
    dc)

    ignoreType :: ScEnv -> Type -> Bool
    ignoreType ScEnv
    env Type
    ty
      = case Type -> Maybe TyCon
    tyConAppTyCon_maybe Type
    ty of
          Just TyCon
    tycon -> ScEnv -> TyCon -> Bool
    ignoreTyCon ScEnv
    env TyCon
    tycon
          Maybe TyCon
    _          -> Bool
    False

    ignoreTyCon :: ScEnv -> TyCon -> Bool
    ignoreTyCon :: ScEnv -> TyCon -> Bool
    ignoreTyCon ScEnv
    env TyCon
    tycon
      = forall key elt. Uniquable key => UniqFM key elt -> key -> Maybe elt
    lookupUFM (ScEnv -> NameEnv SpecConstrAnnotation
    sc_annotations ScEnv
    env) (TyCon -> Name
    tyConName TyCon
    tycon) forall a. Eq a => a -> a -> Bool
    == forall a. a -> Maybe a
    Just SpecConstrAnnotation
    NoSpecConstr

    forceSpecBndr :: ScEnv -> Id -> Bool
    forceSpecBndr ScEnv
    env Id
    var = ScEnv -> Type -> Bool
    forceSpecFunTy ScEnv
    env forall b c a. (b -> c) -> (a -> b) -> a -> c
    . forall a b. (a, b) -> b
    snd forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Type -> ([Id], Type)
    splitForAllTyCoVars forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Id -> Type
    varType forall a b. (a -> b) -> a -> b
    $ Id
    var

    forceSpecFunTy :: ScEnv -> Type -> Bool
    forceSpecFunTy :: ScEnv -> Type -> Bool
    forceSpecFunTy ScEnv
    env = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (ScEnv -> Type -> Bool
    forceSpecArgTy ScEnv
    env) forall b c a. (b -> c) -> (a -> b) -> a -> c
    . forall a b. (a -> b) -> [a] -> [b]
    map forall a. Scaled a -> a
    scaledThing forall b c a. (b -> c) -> (a -> b) -> a -> c
    . forall a b. (a, b) -> a
    fst forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Type -> ([Scaled Type], Type)
    splitFunTys

    forceSpecArgTy :: ScEnv -> Type -> Bool
    forceSpecArgTy :: ScEnv -> Type -> Bool
    forceSpecArgTy ScEnv
    env Type
    ty
      | Just Type
    ty' <- Type -> Maybe Type
    coreView Type
    ty = ScEnv -> Type -> Bool
    forceSpecArgTy ScEnv
    env Type
    ty'

    forceSpecArgTy ScEnv
    env Type
    ty
      | Just (TyCon
    tycon, [Type]
    tys) <- HasDebugCallStack => Type -> Maybe (TyCon, [Type])
    splitTyConApp_maybe Type
    ty
      , TyCon
    tycon forall a. Eq a => a -> a -> Bool
    /= TyCon
    funTyCon
          = TyCon -> Unique
    tyConUnique TyCon
    tycon forall a. Eq a => a -> a -> Bool
    == Unique
    specTyConKey
            Bool -> Bool -> Bool
    || forall key elt. Uniquable key => UniqFM key elt -> key -> Maybe elt
    lookupUFM (ScEnv -> NameEnv SpecConstrAnnotation
    sc_annotations ScEnv
    env) (TyCon -> Name
    tyConName TyCon
    tycon) forall a. Eq a => a -> a -> Bool
    == forall a. a -> Maybe a
    Just SpecConstrAnnotation
    ForceSpecConstr
            Bool -> Bool -> Bool
    || forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (ScEnv -> Type -> Bool
    forceSpecArgTy ScEnv
    env) [Type]
    tys

    forceSpecArgTy ScEnv
    _ Type
    _ = Bool
    False

    {-
    Note [Add scrutinee to ValueEnv too]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider this:
       case x of y
         (a,b) -> case b of c
                    I# v -> ...(f y)...
    By the time we get to the call (f y), the ValueEnv
    will have a binding for y, and for c
        y -> (a,b)
        c -> I# v
    BUT that's not enough!  Looking at the call (f y) we
    see that y is pair (a,b), but we also need to know what 'b' is.
    So in extendCaseBndrs we must *also* add the binding
       b -> I# v
    else we lose a useful specialisation for f.  This is necessary even
    though the simplifier has systematically replaced uses of 'x' with 'y'
    and 'b' with 'c' in the code.  The use of 'b' in the ValueEnv came
    from outside the case.  See #4908 for the live example.

    Note [Avoiding exponential blowup]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The sc_count field of the ScEnv says how many times we are prepared to
    duplicate a single function.  But we must take care with recursive
    specialisations.  Consider

            let $j1 = let $j2 = let $j3 = ...
                                in
                                ...$j3...
                      in
                      ...$j2...
            in
            ...$j1...

    If we specialise $j1 then in each specialisation (as well as the original)
    we can specialise $j2, and similarly $j3.  Even if we make just *one*
    specialisation of each, because we also have the original we'll get 2^n
    copies of $j3, which is not good.

    So when recursively specialising we divide the sc_count by the number of
    copies we are making at this level, including the original.

    ************************************************************************
    *                                                                      *
    \subsection{Usage information: flows upwards}
    *                                                                      *
    ************************************************************************
    -}

    data ScUsage
       = SCU {
            ScUsage -> CallEnv
    scu_calls :: CallEnv,           -- Calls
                                            -- The functions are a subset of the
                                            --      RecFuns in the ScEnv

            ScUsage -> IdEnv ArgOcc
    scu_occs :: !(IdEnv ArgOcc)     -- Information on argument occurrences
         }                                  -- The domain is OutIds

    type CallEnv = IdEnv [Call]
    data Call = Call Id [CoreArg] ValueEnv
            -- The arguments of the call, together with the
            -- env giving the constructor bindings at the call site
            -- We keep the function mainly for debug output

    instance Outputable ScUsage where
      ppr :: ScUsage -> SDoc
    ppr (SCU { scu_calls :: ScUsage -> CallEnv
    scu_calls = CallEnv
    calls, scu_occs :: ScUsage -> IdEnv ArgOcc
    scu_occs = IdEnv ArgOcc
    occs })
        = String -> SDoc
    text String
    "SCU" SDoc -> SDoc -> SDoc
    <+> SDoc -> SDoc
    braces ([SDoc] -> SDoc
    sep [ PtrString -> SDoc
    ptext (String -> PtrString
    sLit String
    "calls =") SDoc -> SDoc -> SDoc
    <+> forall a. Outputable a => a -> SDoc
    ppr CallEnv
    calls
                                             , String -> SDoc
    text String
    "occs =" SDoc -> SDoc -> SDoc
    <+> forall a. Outputable a => a -> SDoc
    ppr IdEnv ArgOcc
    occs ])

    instance Outputable Call where
      ppr :: Call -> SDoc
    ppr (Call Id
    fn [Expr Id]
    args ValueEnv
    _) = forall a. Outputable a => a -> SDoc
    ppr Id
    fn SDoc -> SDoc -> SDoc
    <+> [SDoc] -> SDoc
    fsep (forall a b. (a -> b) -> [a] -> [b]
    map forall b. OutputableBndr b => Expr b -> SDoc
    pprParendExpr [Expr Id]
    args)

    nullUsage :: ScUsage
    nullUsage :: ScUsage
    nullUsage = SCU { scu_calls :: CallEnv
    scu_calls = forall a. VarEnv a
    emptyVarEnv, scu_occs :: IdEnv ArgOcc
    scu_occs = forall a. VarEnv a
    emptyVarEnv }

    combineCalls :: CallEnv -> CallEnv -> CallEnv
    combineCalls :: CallEnv -> CallEnv -> CallEnv
    combineCalls = forall a. (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv a
    plusVarEnv_C forall a. [a] -> [a] -> [a]
    (++)

    combineUsage :: ScUsage -> ScUsage -> ScUsage
    combineUsage :: ScUsage -> ScUsage -> ScUsage
    combineUsage ScUsage
    u1 ScUsage
    u2 = SCU { scu_calls :: CallEnv
    scu_calls = CallEnv -> CallEnv -> CallEnv
    combineCalls (ScUsage -> CallEnv
    scu_calls ScUsage
    u1) (ScUsage -> CallEnv
    scu_calls ScUsage
    u2),
                               scu_occs :: IdEnv ArgOcc
    scu_occs  = forall a. (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv a
    plusVarEnv_C ArgOcc -> ArgOcc -> ArgOcc
    combineOcc (ScUsage -> IdEnv ArgOcc
    scu_occs ScUsage
    u1) (ScUsage -> IdEnv ArgOcc
    scu_occs ScUsage
    u2) }

    combineUsages :: [ScUsage] -> ScUsage
    combineUsages :: [ScUsage] -> ScUsage
    combineUsages [] = ScUsage
    nullUsage
    combineUsages [ScUsage]
    us = forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
    foldr1 ScUsage -> ScUsage -> ScUsage
    combineUsage [ScUsage]
    us

    lookupOccs :: ScUsage -> [OutVar] -> (ScUsage, [ArgOcc])
    lookupOccs :: ScUsage -> [Id] -> (ScUsage, [ArgOcc])
    lookupOccs (SCU { scu_calls :: ScUsage -> CallEnv
    scu_calls = CallEnv
    sc_calls, scu_occs :: ScUsage -> IdEnv ArgOcc
    scu_occs = IdEnv ArgOcc
    sc_occs }) [Id]
    bndrs
      = (SCU {scu_calls :: CallEnv
    scu_calls = CallEnv
    sc_calls, scu_occs :: IdEnv ArgOcc
    scu_occs = forall a. VarEnv a -> [Id] -> VarEnv a
    delVarEnvList IdEnv ArgOcc
    sc_occs [Id]
    bndrs},
         [forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv IdEnv ArgOcc
    sc_occs Id
    b forall a. Maybe a -> a -> a
    `orElse` ArgOcc
    NoOcc | Id
    b <- [Id]
    bndrs])

    data ArgOcc = NoOcc     -- Doesn't occur at all; or a type argument
                | UnkOcc    -- Used in some unknown way

                | ScrutOcc  -- See Note [ScrutOcc]
                     (DataConEnv [ArgOcc])   -- How the sub-components are used

    type DataConEnv a = UniqFM DataCon a     -- Keyed by DataCon

    {- Note  [ScrutOcc]
    ~~~~~~~~~~~~~~~~~~~
    An occurrence of ScrutOcc indicates that the thing, or a `cast` version of the thing,
    is *only* taken apart or applied.

      Functions, literal: ScrutOcc emptyUFM
      Data constructors:  ScrutOcc subs,

    where (subs :: UniqFM [ArgOcc]) gives usage of the *pattern-bound* components,
    The domain of the UniqFM is the Unique of the data constructor

    The [ArgOcc] is the occurrences of the *pattern-bound* components
    of the data structure.  E.g.
            data T a = forall b. MkT a b (b->a)
    A pattern binds b, x::a, y::b, z::b->a, but not 'a'!

    -}

    instance Outputable ArgOcc where
      ppr :: ArgOcc -> SDoc
    ppr (ScrutOcc DataConEnv [ArgOcc]
    xs) = String -> SDoc
    text String
    "scrut-occ" SDoc -> SDoc -> SDoc
    <> forall a. Outputable a => a -> SDoc
    ppr DataConEnv [ArgOcc]
    xs
      ppr ArgOcc
    UnkOcc        = String -> SDoc
    text String
    "unk-occ"
      ppr ArgOcc
    NoOcc         = String -> SDoc
    text String
    "no-occ"

    evalScrutOcc :: ArgOcc
    evalScrutOcc :: ArgOcc
    evalScrutOcc = DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc forall key elt. UniqFM key elt
    emptyUFM

    -- Experimentally, this version of combineOcc makes ScrutOcc "win", so
    -- that if the thing is scrutinised anywhere then we get to see that
    -- in the overall result, even if it's also used in a boxed way
    -- This might be too aggressive; see Note [Reboxing] Alternative 3
    combineOcc :: ArgOcc -> ArgOcc -> ArgOcc
    combineOcc :: ArgOcc -> ArgOcc -> ArgOcc
    combineOcc ArgOcc
    NoOcc         ArgOcc
    occ           = ArgOcc
    occ
    combineOcc ArgOcc
    occ           ArgOcc
    NoOcc         = ArgOcc
    occ
    combineOcc (ScrutOcc DataConEnv [ArgOcc]
    xs) (ScrutOcc DataConEnv [ArgOcc]
    ys) = DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc (forall elt key.
    (elt -> elt -> elt)
    -> UniqFM key elt -> UniqFM key elt -> UniqFM key elt
    plusUFM_C [ArgOcc] -> [ArgOcc] -> [ArgOcc]
    combineOccs DataConEnv [ArgOcc]
    xs DataConEnv [ArgOcc]
    ys)
    combineOcc ArgOcc
    UnkOcc        (ScrutOcc DataConEnv [ArgOcc]
    ys) = DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc DataConEnv [ArgOcc]
    ys
    combineOcc (ScrutOcc DataConEnv [ArgOcc]
    xs) ArgOcc
    UnkOcc        = DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc DataConEnv [ArgOcc]
    xs
    combineOcc ArgOcc
    UnkOcc        ArgOcc
    UnkOcc        = ArgOcc
    UnkOcc

    combineOccs :: [ArgOcc] -> [ArgOcc] -> [ArgOcc]
    combineOccs :: [ArgOcc] -> [ArgOcc] -> [ArgOcc]
    combineOccs [ArgOcc]
    xs [ArgOcc]
    ys = forall a b c. String -> (a -> b -> c) -> [a] -> [b] -> [c]
    zipWithEqual String
    "combineOccs" ArgOcc -> ArgOcc -> ArgOcc
    combineOcc [ArgOcc]
    xs [ArgOcc]
    ys

    setScrutOcc :: ScEnv -> ScUsage -> OutExpr -> ArgOcc -> ScUsage
    -- _Overwrite_ the occurrence info for the scrutinee, if the scrutinee
    -- is a variable, and an interesting variable
    setScrutOcc :: ScEnv -> ScUsage -> Expr Id -> ArgOcc -> ScUsage
    setScrutOcc ScEnv
    env ScUsage
    usg (Cast Expr Id
    e Coercion
    _) ArgOcc
    occ      = ScEnv -> ScUsage -> Expr Id -> ArgOcc -> ScUsage
    setScrutOcc ScEnv
    env ScUsage
    usg Expr Id
    e ArgOcc
    occ
    setScrutOcc ScEnv
    env ScUsage
    usg (Tick CoreTickish
    _ Expr Id
    e) ArgOcc
    occ      = ScEnv -> ScUsage -> Expr Id -> ArgOcc -> ScUsage
    setScrutOcc ScEnv
    env ScUsage
    usg Expr Id
    e ArgOcc
    occ
    setScrutOcc ScEnv
    env ScUsage
    usg (Var Id
    v)    ArgOcc
    occ
      | Just HowBound
    RecArg <- ScEnv -> Id -> Maybe HowBound
    lookupHowBound ScEnv
    env Id
    v = ScUsage
    usg { scu_occs :: IdEnv ArgOcc
    scu_occs = forall a. VarEnv a -> Id -> a -> VarEnv a
    extendVarEnv (ScUsage -> IdEnv ArgOcc
    scu_occs ScUsage
    usg) Id
    v ArgOcc
    occ }
      | Bool
    otherwise                           = ScUsage
    usg
    setScrutOcc ScEnv
    _env ScUsage
    usg Expr Id
    _other ArgOcc
    _occ        -- Catch-all
      = ScUsage
    usg

    {-
    ************************************************************************
    *                                                                      *
    \subsection{The main recursive function}
    *                                                                      *
    ************************************************************************

    The main recursive function gathers up usage information, and
    creates specialised versions of functions.
    -}

    scExpr, scExpr' :: ScEnv -> CoreExpr -> UniqSM (ScUsage, CoreExpr)
            -- The unique supply is needed when we invent
            -- a new name for the specialised function and its args

    scExpr :: ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    e = ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr' ScEnv
    env Expr Id
    e

    scExpr' :: ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr' ScEnv
    env (Var Id
    v)      = case ScEnv -> Id -> Expr Id
    scSubstId ScEnv
    env Id
    v of
                                Var Id
    v' -> forall (m :: * -> *) a. Monad m => a -> m a
    return (ScEnv -> Id -> [Expr Id] -> ScUsage
    mkVarUsage ScEnv
    env Id
    v' [], forall b. Id -> Expr b
    Var Id
    v')
                                Expr Id
    e'     -> ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr (ScEnv -> ScEnv
    zapScSubst ScEnv
    env) Expr Id
    e'

    scExpr' ScEnv
    env (Type Type
    t)     = forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, forall b. Type -> Expr b
    Type (ScEnv -> Type -> Type
    scSubstTy ScEnv
    env Type
    t))
    scExpr' ScEnv
    env (Coercion Coercion
    c) = forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, forall b. Coercion -> Expr b
    Coercion (ScEnv -> Coercion -> Coercion
    scSubstCo ScEnv
    env Coercion
    c))
    scExpr' ScEnv
    _   e :: Expr Id
    e@(Lit {})   = forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, Expr Id
    e)
    scExpr' ScEnv
    env (Tick CoreTickish
    t Expr Id
    e)   = do (ScUsage
    usg, Expr Id
    e') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    e
                                  forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg, forall b. CoreTickish -> Expr b -> Expr b
    Tick CoreTickish
    t Expr Id
    e')
    scExpr' ScEnv
    env (Cast Expr Id
    e Coercion
    co)  = do (ScUsage
    usg, Expr Id
    e') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    e
                                  forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg, Expr Id -> Coercion -> Expr Id
    mkCast Expr Id
    e' (ScEnv -> Coercion -> Coercion
    scSubstCo ScEnv
    env Coercion
    co))
                                  -- Important to use mkCast here
                                  -- See Note [SpecConstr call patterns]
    scExpr' ScEnv
    env e :: Expr Id
    e@(App Expr Id
    _ Expr Id
    _)  = ScEnv -> (Expr Id, [Expr Id]) -> UniqSM (ScUsage, Expr Id)
    scApp ScEnv
    env (forall b. Expr b -> (Expr b, [Expr b])
    collectArgs Expr Id
    e)
    scExpr' ScEnv
    env (Lam Id
    b Expr Id
    e)    = do let (ScEnv
    env', Id
    b') = ScEnv -> Id -> (ScEnv, Id)
    extendBndr ScEnv
    env Id
    b
                                  (ScUsage
    usg, Expr Id
    e') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env' Expr Id
    e
                                  forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg, forall b. b -> Expr b -> Expr b
    Lam Id
    b' Expr Id
    e')

    scExpr' ScEnv
    env (Case Expr Id
    scrut Id
    b Type
    ty [Alt Id]
    alts)
      = do  { (ScUsage
    scrut_usg, Expr Id
    scrut') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    scrut
            ; case ValueEnv -> Expr Id -> Maybe Value
    isValue (ScEnv -> ValueEnv
    sc_vals ScEnv
    env) Expr Id
    scrut' of
                    Just (ConVal AltCon
    con [Expr Id]
    args) -> AltCon -> [Expr Id] -> Expr Id -> UniqSM (ScUsage, Expr Id)
    sc_con_app AltCon
    con [Expr Id]
    args Expr Id
    scrut'
                    Maybe Value
    _other                 -> ScUsage -> Expr Id -> UniqSM (ScUsage, Expr Id)
    sc_vanilla ScUsage
    scrut_usg Expr Id
    scrut'
            }
      where
        sc_con_app :: AltCon -> [Expr Id] -> Expr Id -> UniqSM (ScUsage, Expr Id)
    sc_con_app AltCon
    con [Expr Id]
    args Expr Id
    scrut'  -- Known constructor; simplify
         = do { let Alt AltCon
    _ [Id]
    bs Expr Id
    rhs = forall b. AltCon -> [Alt b] -> Maybe (Alt b)
    findAlt AltCon
    con [Alt Id]
    alts
                                      forall a. Maybe a -> a -> a
    `orElse` forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt AltCon
    DEFAULT [] (Type -> Expr Id
    mkImpossibleExpr Type
    ty)
                    alt_env' :: ScEnv
    alt_env'     = ScEnv -> [(Id, Expr Id)] -> ScEnv
    extendScSubstList ScEnv
    env ((Id
    b,Expr Id
    scrut') forall a. a -> [a] -> [a]
    : [Id]
    bs forall a b. [a] -> [b] -> [(a, b)]
    `zip` AltCon -> [Expr Id] -> [Expr Id]
    trimConArgs AltCon
    con [Expr Id]
    args)
              ; ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    alt_env' Expr Id
    rhs }

        sc_vanilla :: ScUsage -> Expr Id -> UniqSM (ScUsage, Expr Id)
    sc_vanilla ScUsage
    scrut_usg Expr Id
    scrut' -- Normal case
         = do { let (ScEnv
    alt_env,Id
    b') = HowBound -> ScEnv -> Id -> (ScEnv, Id)
    extendBndrWith HowBound
    RecArg ScEnv
    env Id
    b
                            -- Record RecArg for the components

              ; ([ScUsage]
    alt_usgs, [ArgOcc]
    alt_occs, [Alt Id]
    alts')
                    <- forall (m :: * -> *) a b c d.
    Monad m =>
    (a -> m (b, c, d)) -> [a] -> m ([b], [c], [d])
    mapAndUnzip3M (ScEnv
    -> Expr Id -> Id -> Alt Id -> UniqSM (ScUsage, ArgOcc, Alt Id)
    sc_alt ScEnv
    alt_env Expr Id
    scrut' Id
    b') [Alt Id]
    alts

              ; let scrut_occ :: ArgOcc
    scrut_occ  = forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr ArgOcc -> ArgOcc -> ArgOcc
    combineOcc ArgOcc
    NoOcc [ArgOcc]
    alt_occs
                    scrut_usg' :: ScUsage
    scrut_usg' = ScEnv -> ScUsage -> Expr Id -> ArgOcc -> ScUsage
    setScrutOcc ScEnv
    env ScUsage
    scrut_usg Expr Id
    scrut' ArgOcc
    scrut_occ
                    -- The combined usage of the scrutinee is given
                    -- by scrut_occ, which is passed to scScrut, which
                    -- in turn treats a bare-variable scrutinee specially

              ; forall (m :: * -> *) a. Monad m => a -> m a
    return (forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr ScUsage -> ScUsage -> ScUsage
    combineUsage ScUsage
    scrut_usg' [ScUsage]
    alt_usgs,
                        forall b. Expr b -> b -> Type -> [Alt b] -> Expr b
    Case Expr Id
    scrut' Id
    b' (ScEnv -> Type -> Type
    scSubstTy ScEnv
    env Type
    ty) [Alt Id]
    alts') }

        sc_alt :: ScEnv
    -> Expr Id -> Id -> Alt Id -> UniqSM (ScUsage, ArgOcc, Alt Id)
    sc_alt ScEnv
    env Expr Id
    scrut' Id
    b' (Alt AltCon
    con [Id]
    bs Expr Id
    rhs)
         = do { let (ScEnv
    env1, [Id]
    bs1) = HowBound -> ScEnv -> [Id] -> (ScEnv, [Id])
    extendBndrsWith HowBound
    RecArg ScEnv
    env [Id]
    bs
                    (ScEnv
    env2, [Id]
    bs2) = ScEnv -> Expr Id -> Id -> AltCon -> [Id] -> (ScEnv, [Id])
    extendCaseBndrs ScEnv
    env1 Expr Id
    scrut' Id
    b' AltCon
    con [Id]
    bs1
              ; (ScUsage
    usg, Expr Id
    rhs') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env2 Expr Id
    rhs
              ; let (ScUsage
    usg', ArgOcc
    b_occ:[ArgOcc]
    arg_occs) = ScUsage -> [Id] -> (ScUsage, [ArgOcc])
    lookupOccs ScUsage
    usg (Id
    b'forall a. a -> [a] -> [a]
    :[Id]
    bs2)
                    scrut_occ :: ArgOcc
    scrut_occ = case AltCon
    con of
                                   DataAlt DataCon
    dc -> DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc (forall key elt. Uniquable key => key -> elt -> UniqFM key elt
    unitUFM DataCon
    dc [ArgOcc]
    arg_occs)
                                   AltCon
    _          -> DataConEnv [ArgOcc] -> ArgOcc
    ScrutOcc forall key elt. UniqFM key elt
    emptyUFM
              ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg', ArgOcc
    b_occ ArgOcc -> ArgOcc -> ArgOcc
    `combineOcc` ArgOcc
    scrut_occ, forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt AltCon
    con [Id]
    bs2 Expr Id
    rhs') }

    scExpr' ScEnv
    env (Let (NonRec Id
    bndr Expr Id
    rhs) Expr Id
    body)
      | Id -> Bool
    isTyVar Id
    bndr        -- Type-lets may be created by doBeta
      = ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr' (ScEnv -> Id -> Expr Id -> ScEnv
    extendScSubst ScEnv
    env Id
    bndr Expr Id
    rhs) Expr Id
    body

      | Bool
    otherwise
      = do  { let (ScEnv
    body_env, Id
    bndr') = ScEnv -> Id -> (ScEnv, Id)
    extendBndr ScEnv
    env Id
    bndr
            ; RhsInfo
    rhs_info  <- ScEnv -> (Id, Expr Id) -> UniqSM RhsInfo
    scRecRhs ScEnv
    env (Id
    bndr',Expr Id
    rhs)

            ; let body_env2 :: ScEnv
    body_env2 = ScEnv -> [Id] -> HowBound -> ScEnv
    extendHowBound ScEnv
    body_env [Id
    bndr'] HowBound
    RecFun
                               -- Note [Local let bindings]
                  rhs' :: Expr Id
    rhs'      = RhsInfo -> Expr Id
    ri_new_rhs RhsInfo
    rhs_info
                  body_env3 :: ScEnv
    body_env3 = ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv ScEnv
    body_env2 Id
    bndr' (ValueEnv -> Expr Id -> Maybe Value
    isValue (ScEnv -> ValueEnv
    sc_vals ScEnv
    env) Expr Id
    rhs')

            ; (ScUsage
    body_usg, Expr Id
    body') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    body_env3 Expr Id
    body

              -- NB: For non-recursive bindings we inherit sc_force flag from
              -- the parent function (see Note [Forcing specialisation])
            ; (ScUsage
    spec_usg, SpecInfo
    specs) <- ScEnv -> ScUsage -> RhsInfo -> UniqSM (ScUsage, SpecInfo)
    specNonRec ScEnv
    env ScUsage
    body_usg RhsInfo
    rhs_info

            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    body_usg { scu_calls :: CallEnv
    scu_calls = ScUsage -> CallEnv
    scu_calls ScUsage
    body_usg forall a. VarEnv a -> Id -> VarEnv a
    `delVarEnv` Id
    bndr' }
                        ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    spec_usg,  -- Note [spec_usg includes rhs_usg]
                      forall b. [Bind b] -> Expr b -> Expr b
    mkLets [forall b. b -> Expr b -> Bind b
    NonRec Id
    b Expr Id
    r | (Id
    b,Expr Id
    r) <- RhsInfo -> SpecInfo -> [(Id, Expr Id)]
    ruleInfoBinds RhsInfo
    rhs_info SpecInfo
    specs] Expr Id
    body')
            }

    -- A *local* recursive group: see Note [Local recursive groups]
    scExpr' ScEnv
    env (Let (Rec [(Id, Expr Id)]
    prs) Expr Id
    body)
      = do  { let ([Id]
    bndrs,[Expr Id]
    rhss)      = forall a b. [(a, b)] -> ([a], [b])
    unzip [(Id, Expr Id)]
    prs
                  (ScEnv
    rhs_env1,[Id]
    bndrs') = ScEnv -> [Id] -> (ScEnv, [Id])
    extendRecBndrs ScEnv
    env [Id]
    bndrs
                  rhs_env2 :: ScEnv
    rhs_env2          = ScEnv -> [Id] -> HowBound -> ScEnv
    extendHowBound ScEnv
    rhs_env1 [Id]
    bndrs' HowBound
    RecFun
                  force_spec :: Bool
    force_spec        = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (ScEnv -> Id -> Bool
    forceSpecBndr ScEnv
    env) [Id]
    bndrs'
                    -- Note [Forcing specialisation]

            ; [RhsInfo]
    rhs_infos <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM (ScEnv -> (Id, Expr Id) -> UniqSM RhsInfo
    scRecRhs ScEnv
    rhs_env2) ([Id]
    bndrs' forall a b. [a] -> [b] -> [(a, b)]
    `zip` [Expr Id]
    rhss)
            ; (ScUsage
    body_usg, Expr Id
    body')     <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    rhs_env2 Expr Id
    body

            -- NB: start specLoop from body_usg
            ; (ScUsage
    spec_usg, [SpecInfo]
    specs) <- TopLevelFlag
    -> ScEnv -> ScUsage -> [RhsInfo] -> UniqSM (ScUsage, [SpecInfo])
    specRec TopLevelFlag
    NotTopLevel (ScEnv -> Bool -> ScEnv
    scForce ScEnv
    rhs_env2 Bool
    force_spec)
                                           ScUsage
    body_usg [RhsInfo]
    rhs_infos
                    -- Do not unconditionally generate specialisations from rhs_usgs
                    -- Instead use them only if we find an unspecialised call
                    -- See Note [Local recursive groups]

            ; let all_usg :: ScUsage
    all_usg = ScUsage
    spec_usg ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    body_usg  -- Note [spec_usg includes rhs_usg]
                  bind' :: CoreBind
    bind'   = forall b. [(b, Expr b)] -> Bind b
    Rec (forall (t :: * -> *) a. Foldable t => t [a] -> [a]
    concat (forall a b c. String -> (a -> b -> c) -> [a] -> [b] -> [c]
    zipWithEqual String
    "scExpr'" RhsInfo -> SpecInfo -> [(Id, Expr Id)]
    ruleInfoBinds [RhsInfo]
    rhs_infos [SpecInfo]
    specs))
                            -- zipWithEqual: length of returned [SpecInfo]
                            -- should be the same as incoming [RhsInfo]

            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    all_usg { scu_calls :: CallEnv
    scu_calls = ScUsage -> CallEnv
    scu_calls ScUsage
    all_usg forall a. VarEnv a -> [Id] -> VarEnv a
    `delVarEnvList` [Id]
    bndrs' },
                      forall b. Bind b -> Expr b -> Expr b
    Let CoreBind
    bind' Expr Id
    body') }

    {-
    Note [Local let bindings]
    ~~~~~~~~~~~~~~~~~~~~~~~~~
    It is not uncommon to find this

       let $j = \x. <blah> in ...$j True...$j True...

    Here $j is an arbitrary let-bound function, but it often comes up for
    join points.  We might like to specialise $j for its call patterns.
    Notice the difference from a letrec, where we look for call patterns
    in the *RHS* of the function.  Here we look for call patterns in the
    *body* of the let.

    At one point I predicated this on the RHS mentioning the outer
    recursive function, but that's not essential and might even be
    harmful.  I'm not sure.
    -}

    scApp :: ScEnv -> (InExpr, [InExpr]) -> UniqSM (ScUsage, CoreExpr)

    scApp :: ScEnv -> (Expr Id, [Expr Id]) -> UniqSM (ScUsage, Expr Id)
    scApp ScEnv
    env (Var Id
    fn, [Expr Id]
    args)        -- Function is a variable
      = ASSERT( not (null args) )
        do  { [(ScUsage, Expr Id)]
    args_w_usgs <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM (ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env) [Expr Id]
    args
            ; let ([ScUsage]
    arg_usgs, [Expr Id]
    args') = forall a b. [(a, b)] -> ([a], [b])
    unzip [(ScUsage, Expr Id)]
    args_w_usgs
                  arg_usg :: ScUsage
    arg_usg = [ScUsage] -> ScUsage
    combineUsages [ScUsage]
    arg_usgs
            ; case ScEnv -> Id -> Expr Id
    scSubstId ScEnv
    env Id
    fn of
                fn' :: Expr Id
    fn'@(Lam {}) -> ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr (ScEnv -> ScEnv
    zapScSubst ScEnv
    env) (Expr Id -> [Expr Id] -> Expr Id
    doBeta Expr Id
    fn' [Expr Id]
    args')
                            -- Do beta-reduction and try again

                Var Id
    fn' -> forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    arg_usg ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScEnv -> Id -> [Expr Id] -> ScUsage
    mkVarUsage ScEnv
    env Id
    fn' [Expr Id]
    args',
                                   forall b. Expr b -> [Expr b] -> Expr b
    mkApps (forall b. Id -> Expr b
    Var Id
    fn') [Expr Id]
    args')

                Expr Id
    other_fn' -> forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    arg_usg, forall b. Expr b -> [Expr b] -> Expr b
    mkApps Expr Id
    other_fn' [Expr Id]
    args') }
                    -- NB: doing this ignores any usage info from the substituted
                    --     function, but I don't think that matters.  If it does
                    --     we can fix it.
      where
        doBeta :: OutExpr -> [OutExpr] -> OutExpr
        -- ToDo: adjust for System IF
        doBeta :: Expr Id -> [Expr Id] -> Expr Id
    doBeta (Lam Id
    bndr Expr Id
    body) (Expr Id
    arg : [Expr Id]
    args) = forall b. Bind b -> Expr b -> Expr b
    Let (forall b. b -> Expr b -> Bind b
    NonRec Id
    bndr Expr Id
    arg) (Expr Id -> [Expr Id] -> Expr Id
    doBeta Expr Id
    body [Expr Id]
    args)
        doBeta Expr Id
    fn              [Expr Id]
    args         = forall b. Expr b -> [Expr b] -> Expr b
    mkApps Expr Id
    fn [Expr Id]
    args

    -- The function is almost always a variable, but not always.
    -- In particular, if this pass follows float-in,
    -- which it may, we can get
    --      (let f = ...f... in f) arg1 arg2
    scApp ScEnv
    env (Expr Id
    other_fn, [Expr Id]
    args)
      = do  { (ScUsage
    fn_usg,   Expr Id
    fn')   <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    other_fn
            ; ([ScUsage]
    arg_usgs, [Expr Id]
    args') <- forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> m (b, c)) -> [a] -> m ([b], [c])
    mapAndUnzipM (ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env) [Expr Id]
    args
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([ScUsage] -> ScUsage
    combineUsages [ScUsage]
    arg_usgs ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    fn_usg, forall b. Expr b -> [Expr b] -> Expr b
    mkApps Expr Id
    fn' [Expr Id]
    args') }

    ----------------------
    mkVarUsage :: ScEnv -> Id -> [CoreExpr] -> ScUsage
    mkVarUsage :: ScEnv -> Id -> [Expr Id] -> ScUsage
    mkVarUsage ScEnv
    env Id
    fn [Expr Id]
    args
      = case ScEnv -> Id -> Maybe HowBound
    lookupHowBound ScEnv
    env Id
    fn of
            Just HowBound
    RecFun -> SCU { scu_calls :: CallEnv
    scu_calls = forall a. Id -> a -> VarEnv a
    unitVarEnv Id
    fn [Id -> [Expr Id] -> ValueEnv -> Call
    Call Id
    fn [Expr Id]
    args (ScEnv -> ValueEnv
    sc_vals ScEnv
    env)]
                               , scu_occs :: IdEnv ArgOcc
    scu_occs  = forall a. VarEnv a
    emptyVarEnv }
            Just HowBound
    RecArg -> SCU { scu_calls :: CallEnv
    scu_calls = forall a. VarEnv a
    emptyVarEnv
                               , scu_occs :: IdEnv ArgOcc
    scu_occs  = forall a. Id -> a -> VarEnv a
    unitVarEnv Id
    fn ArgOcc
    arg_occ }
            Maybe HowBound
    Nothing     -> ScUsage
    nullUsage
      where
        -- I rather think we could use UnkOcc all the time
        arg_occ :: ArgOcc
    arg_occ | forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [Expr Id]
    args = ArgOcc
    UnkOcc
                | Bool
    otherwise = ArgOcc
    evalScrutOcc

    ----------------------
    scTopBindEnv :: ScEnv -> CoreBind -> UniqSM (ScEnv, CoreBind)
    scTopBindEnv :: ScEnv -> CoreBind -> UniqSM (ScEnv, CoreBind)
    scTopBindEnv ScEnv
    env (Rec [(Id, Expr Id)]
    prs)
      = do  { let (ScEnv
    rhs_env1,[Id]
    bndrs') = ScEnv -> [Id] -> (ScEnv, [Id])
    extendRecBndrs ScEnv
    env [Id]
    bndrs
                  rhs_env2 :: ScEnv
    rhs_env2          = ScEnv -> [Id] -> HowBound -> ScEnv
    extendHowBound ScEnv
    rhs_env1 [Id]
    bndrs HowBound
    RecFun

                  prs' :: [(Id, Expr Id)]
    prs'              = forall a b. [a] -> [b] -> [(a, b)]
    zip [Id]
    bndrs' [Expr Id]
    rhss
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScEnv
    rhs_env2, forall b. [(b, Expr b)] -> Bind b
    Rec [(Id, Expr Id)]
    prs') }
      where
        ([Id]
    bndrs,[Expr Id]
    rhss) = forall a b. [(a, b)] -> ([a], [b])
    unzip [(Id, Expr Id)]
    prs

    scTopBindEnv ScEnv
    env (NonRec Id
    bndr Expr Id
    rhs)
      = do  { let (ScEnv
    env1, Id
    bndr') = ScEnv -> Id -> (ScEnv, Id)
    extendBndr ScEnv
    env Id
    bndr
                  env2 :: ScEnv
    env2          = ScEnv -> Id -> Maybe Value -> ScEnv
    extendValEnv ScEnv
    env1 Id
    bndr' (ValueEnv -> Expr Id -> Maybe Value
    isValue (ScEnv -> ValueEnv
    sc_vals ScEnv
    env) Expr Id
    rhs)
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScEnv
    env2, forall b. b -> Expr b -> Bind b
    NonRec Id
    bndr' Expr Id
    rhs) }

    ----------------------
    scTopBind :: ScEnv -> ScUsage -> CoreBind -> UniqSM (ScUsage, CoreBind)

    {-
    scTopBind _ usage _
      | pprTrace "scTopBind_usage" (ppr (scu_calls usage)) False
      = error "false"
    -}

    scTopBind :: ScEnv -> ScUsage -> CoreBind -> UniqSM (ScUsage, CoreBind)
    scTopBind ScEnv
    env ScUsage
    body_usage (Rec [(Id, Expr Id)]
    prs)
      | Just Int
    threshold <- ScEnv -> Maybe Int
    sc_size ScEnv
    env
      , Bool -> Bool
    not Bool
    force_spec
      , Bool -> Bool
    not (forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    all (UnfoldingOpts -> Int -> Expr Id -> Bool
    couldBeSmallEnoughToInline (ScEnv -> UnfoldingOpts
    sc_uf_opts ScEnv
    env) Int
    threshold) [Expr Id]
    rhss)
                    -- No specialisation
      = -- pprTrace "scTopBind: nospec" (ppr bndrs) $
        do  { ([ScUsage]
    rhs_usgs, [Expr Id]
    rhss')   <- forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> m (b, c)) -> [a] -> m ([b], [c])
    mapAndUnzipM (ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env) [Expr Id]
    rhss
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    body_usage ScUsage -> ScUsage -> ScUsage
    `combineUsage` [ScUsage] -> ScUsage
    combineUsages [ScUsage]
    rhs_usgs, forall b. [(b, Expr b)] -> Bind b
    Rec ([Id]
    bndrs forall a b. [a] -> [b] -> [(a, b)]
    `zip` [Expr Id]
    rhss')) }

      | Bool
    otherwise   -- Do specialisation
      = do  { [RhsInfo]
    rhs_infos <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM (ScEnv -> (Id, Expr Id) -> UniqSM RhsInfo
    scRecRhs ScEnv
    env) [(Id, Expr Id)]
    prs

            ; (ScUsage
    spec_usage, [SpecInfo]
    specs) <- TopLevelFlag
    -> ScEnv -> ScUsage -> [RhsInfo] -> UniqSM (ScUsage, [SpecInfo])
    specRec TopLevelFlag
    TopLevel (ScEnv -> Bool -> ScEnv
    scForce ScEnv
    env Bool
    force_spec)
                                             ScUsage
    body_usage [RhsInfo]
    rhs_infos

            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    body_usage ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    spec_usage,
                      forall b. [(b, Expr b)] -> Bind b
    Rec (forall (t :: * -> *) a. Foldable t => t [a] -> [a]
    concat (forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
    zipWith RhsInfo -> SpecInfo -> [(Id, Expr Id)]
    ruleInfoBinds [RhsInfo]
    rhs_infos [SpecInfo]
    specs))) }
      where
        ([Id]
    bndrs,[Expr Id]
    rhss) = forall a b. [(a, b)] -> ([a], [b])
    unzip [(Id, Expr Id)]
    prs
        force_spec :: Bool
    force_spec   = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (ScEnv -> Id -> Bool
    forceSpecBndr ScEnv
    env) [Id]
    bndrs
          -- Note [Forcing specialisation]

    scTopBind ScEnv
    env ScUsage
    usage (NonRec Id
    bndr Expr Id
    rhs)   -- Oddly, we don't seem to specialise top-level non-rec functions
      = do  { (ScUsage
    rhs_usg', Expr Id
    rhs') <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    env Expr Id
    rhs
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usage ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    rhs_usg', forall b. b -> Expr b -> Bind b
    NonRec Id
    bndr Expr Id
    rhs') }

    ----------------------
    scRecRhs :: ScEnv -> (OutId, InExpr) -> UniqSM RhsInfo
    scRecRhs :: ScEnv -> (Id, Expr Id) -> UniqSM RhsInfo
    scRecRhs ScEnv
    env (Id
    bndr,Expr Id
    rhs)
      = do  { let ([Id]
    arg_bndrs,Expr Id
    body)       = forall b. Expr b -> ([b], Expr b)
    collectBinders Expr Id
    rhs
                  (ScEnv
    body_env, [Id]
    arg_bndrs') = HowBound -> ScEnv -> [Id] -> (ScEnv, [Id])
    extendBndrsWith HowBound
    RecArg ScEnv
    env [Id]
    arg_bndrs
            ; (ScUsage
    body_usg, Expr Id
    body')         <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    body_env Expr Id
    body
            ; let (ScUsage
    rhs_usg, [ArgOcc]
    arg_occs)    = ScUsage -> [Id] -> (ScUsage, [ArgOcc])
    lookupOccs ScUsage
    body_usg [Id]
    arg_bndrs'
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (RI { ri_rhs_usg :: ScUsage
    ri_rhs_usg = ScUsage
    rhs_usg
                         , ri_fn :: Id
    ri_fn = Id
    bndr, ri_new_rhs :: Expr Id
    ri_new_rhs = forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    arg_bndrs' Expr Id
    body'
                         , ri_lam_bndrs :: [Id]
    ri_lam_bndrs = [Id]
    arg_bndrs, ri_lam_body :: Expr Id
    ri_lam_body = Expr Id
    body
                         , ri_arg_occs :: [ArgOcc]
    ri_arg_occs = [ArgOcc]
    arg_occs }) }
                    -- The arg_occs says how the visible,
                    -- lambda-bound binders of the RHS are used
                    -- (including the TyVar binders)
                    -- Two pats are the same if they match both ways

    ----------------------
    ruleInfoBinds :: RhsInfo -> SpecInfo -> [(Id,CoreExpr)]
    ruleInfoBinds :: RhsInfo -> SpecInfo -> [(Id, Expr Id)]
    ruleInfoBinds (RI { ri_fn :: RhsInfo -> Id
    ri_fn = Id
    fn, ri_new_rhs :: RhsInfo -> Expr Id
    ri_new_rhs = Expr Id
    new_rhs })
                  (SI { si_specs :: SpecInfo -> [OneSpec]
    si_specs = [OneSpec]
    specs })
      = [(Id
    id,Expr Id
    rhs) | OS { os_id :: OneSpec -> Id
    os_id = Id
    id, os_rhs :: OneSpec -> Expr Id
    os_rhs = Expr Id
    rhs } <- [OneSpec]
    specs] forall a. [a] -> [a] -> [a]
    ++
                  -- First the specialised bindings

        [(Id
    fn Id -> [CoreRule] -> Id
    `addIdSpecialisations` [CoreRule]
    rules, Expr Id
    new_rhs)]
                  -- And now the original binding
      where
        rules :: [CoreRule]
    rules = [CoreRule
    r | OS { os_rule :: OneSpec -> CoreRule
    os_rule = CoreRule
    r } <- [OneSpec]
    specs]

    {-
    ************************************************************************
    *                                                                      *
                    The specialiser itself
    *                                                                      *
    ************************************************************************
    -}

    data RhsInfo
      = RI { RhsInfo -> Id
    ri_fn :: OutId                 -- The binder
           , RhsInfo -> Expr Id
    ri_new_rhs :: OutExpr          -- The specialised RHS (in current envt)
           , RhsInfo -> ScUsage
    ri_rhs_usg :: ScUsage          -- Usage info from specialising RHS

           , RhsInfo -> [Id]
    ri_lam_bndrs :: [InVar]       -- The *original* RHS (\xs.body)
           , RhsInfo -> Expr Id
    ri_lam_body  :: InExpr        --   Note [Specialise original body]
           , RhsInfo -> [ArgOcc]
    ri_arg_occs  :: [ArgOcc]      -- Info on how the xs occur in body
        }

    data SpecInfo       -- Info about specialisations for a particular Id
      = SI { SpecInfo -> [OneSpec]
    si_specs :: [OneSpec]          -- The specialisations we have generated

           , SpecInfo -> Int
    si_n_specs :: Int              -- Length of si_specs; used for numbering them

           , SpecInfo -> Maybe ScUsage
    si_mb_unspec :: Maybe ScUsage  -- Just cs  => we have not yet used calls in the
           }                                --             from calls in the *original* RHS as
                                            --             seeds for new specialisations;
                                            --             if you decide to do so, here is the
                                            --             RHS usage (which has not yet been
                                            --             unleashed)
                                            -- Nothing => we have
                                            -- See Note [Local recursive groups]
                                            -- See Note [spec_usg includes rhs_usg]

            -- One specialisation: Rule plus definition
    data OneSpec =
      OS { OneSpec -> CallPat
    os_pat  :: CallPat    -- Call pattern that generated this specialisation
         , OneSpec -> CoreRule
    os_rule :: CoreRule   -- Rule connecting original id with the specialisation
         , OneSpec -> Id
    os_id   :: OutId      -- Spec id
         , OneSpec -> Expr Id
    os_rhs  :: OutExpr }  -- Spec rhs

    noSpecInfo :: SpecInfo
    noSpecInfo :: SpecInfo
    noSpecInfo = SI { si_specs :: [OneSpec]
    si_specs = [], si_n_specs :: Int
    si_n_specs = Int
    0, si_mb_unspec :: Maybe ScUsage
    si_mb_unspec = forall a. Maybe a
    Nothing }

    ----------------------
    specNonRec :: ScEnv
               -> ScUsage         -- Body usage
               -> RhsInfo         -- Structure info usage info for un-specialised RHS
               -> UniqSM (ScUsage, SpecInfo)       -- Usage from RHSs (specialised and not)
                                                   --     plus details of specialisations

    specNonRec :: ScEnv -> ScUsage -> RhsInfo -> UniqSM (ScUsage, SpecInfo)
    specNonRec ScEnv
    env ScUsage
    body_usg RhsInfo
    rhs_info
      = ScEnv
    -> CallEnv -> RhsInfo -> SpecInfo -> UniqSM (ScUsage, SpecInfo)
    specialise ScEnv
    env (ScUsage -> CallEnv
    scu_calls ScUsage
    body_usg) RhsInfo
    rhs_info
                   (SpecInfo
    noSpecInfo { si_mb_unspec :: Maybe ScUsage
    si_mb_unspec = forall a. a -> Maybe a
    Just (RhsInfo -> ScUsage
    ri_rhs_usg RhsInfo
    rhs_info) })

    ----------------------
    specRec :: TopLevelFlag -> ScEnv
            -> ScUsage                         -- Body usage
            -> [RhsInfo]                       -- Structure info and usage info for un-specialised RHSs
            -> UniqSM (ScUsage, [SpecInfo])    -- Usage from all RHSs (specialised and not)
                                               --     plus details of specialisations

    specRec :: TopLevelFlag
    -> ScEnv -> ScUsage -> [RhsInfo] -> UniqSM (ScUsage, [SpecInfo])
    specRec TopLevelFlag
    top_lvl ScEnv
    env ScUsage
    body_usg [RhsInfo]
    rhs_infos
      = Int
    -> CallEnv -> ScUsage -> [SpecInfo] -> UniqSM (ScUsage, [SpecInfo])
    go Int
    1 CallEnv
    seed_calls ScUsage
    nullUsage [SpecInfo]
    init_spec_infos
      where
        (CallEnv
    seed_calls, [SpecInfo]
    init_spec_infos)    -- Note [Seeding top-level recursive groups]
           | TopLevelFlag -> Bool
    isTopLevel TopLevelFlag
    top_lvl
           , forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (Id -> Bool
    isExportedId forall b c a. (b -> c) -> (a -> b) -> a -> c
    . RhsInfo -> Id
    ri_fn) [RhsInfo]
    rhs_infos   -- Seed from body and RHSs
           = (CallEnv
    all_calls,     [SpecInfo
    noSpecInfo | RhsInfo
    _ <- [RhsInfo]
    rhs_infos])
           | Bool
    otherwise                              -- Seed from body only
           = (CallEnv
    calls_in_body, [SpecInfo
    noSpecInfo { si_mb_unspec :: Maybe ScUsage
    si_mb_unspec = forall a. a -> Maybe a
    Just (RhsInfo -> ScUsage
    ri_rhs_usg RhsInfo
    ri) }
                             | RhsInfo
    ri <- [RhsInfo]
    rhs_infos])

        calls_in_body :: CallEnv
    calls_in_body = ScUsage -> CallEnv
    scu_calls ScUsage
    body_usg
        calls_in_rhss :: CallEnv
    calls_in_rhss = forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr (CallEnv -> CallEnv -> CallEnv
    combineCalls forall b c a. (b -> c) -> (a -> b) -> a -> c
    . ScUsage -> CallEnv
    scu_calls forall b c a. (b -> c) -> (a -> b) -> a -> c
    . RhsInfo -> ScUsage
    ri_rhs_usg) forall a. VarEnv a
    emptyVarEnv [RhsInfo]
    rhs_infos
        all_calls :: CallEnv
    all_calls = CallEnv
    calls_in_rhss CallEnv -> CallEnv -> CallEnv
    `combineCalls` CallEnv
    calls_in_body

        -- Loop, specialising, until you get no new specialisations
        go :: Int   -- Which iteration of the "until no new specialisations"
                    -- loop we are on; first iteration is 1
           -> CallEnv   -- Seed calls
                        -- Two accumulating parameters:
           -> ScUsage      -- Usage from earlier specialisations
           -> [SpecInfo]   -- Details of specialisations so far
           -> UniqSM (ScUsage, [SpecInfo])
        go :: Int
    -> CallEnv -> ScUsage -> [SpecInfo] -> UniqSM (ScUsage, [SpecInfo])
    go Int
    n_iter CallEnv
    seed_calls ScUsage
    usg_so_far [SpecInfo]
    spec_infos
          | forall a. VarEnv a -> Bool
    isEmptyVarEnv CallEnv
    seed_calls
          = -- pprTrace "specRec1" (vcat [ ppr (map ri_fn rhs_infos)
            --                           , ppr seed_calls
            --                           , ppr body_usg ]) $
            forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg_so_far, [SpecInfo]
    spec_infos)

          -- Limit recursive specialisation
          -- See Note [Limit recursive specialisation]
          | Int
    n_iter forall a. Ord a => a -> a -> Bool
    > ScEnv -> Int
    sc_recursive ScEnv
    env  -- Too many iterations of the 'go' loop
          , ScEnv -> Bool
    sc_force ScEnv
    env Bool -> Bool -> Bool
    || forall a. Maybe a -> Bool
    isNothing (ScEnv -> Maybe Int
    sc_count ScEnv
    env)
               -- If both of these are false, the sc_count
               -- threshold will prevent non-termination
          , forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any ((forall a. Ord a => a -> a -> Bool
    > Int
    the_limit) forall b c a. (b -> c) -> (a -> b) -> a -> c
    . SpecInfo -> Int
    si_n_specs) [SpecInfo]
    spec_infos
          = -- pprTrace "specRec2" (ppr (map (map os_pat . si_specs) spec_infos)) $
            forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    usg_so_far, [SpecInfo]
    spec_infos)

          | Bool
    otherwise
          = -- pprTrace "specRec3" (vcat [ text "bndrs" <+> ppr (map ri_fn rhs_infos)
            --                           , text "iteration" <+> int n_iter
            --                          , text "spec_infos" <+> ppr (map (map os_pat . si_specs) spec_infos)
            --                    ]) $
            do  { [(ScUsage, SpecInfo)]
    specs_w_usg <- forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> b -> m c) -> [a] -> [b] -> m [c]
    zipWithM (ScEnv
    -> CallEnv -> RhsInfo -> SpecInfo -> UniqSM (ScUsage, SpecInfo)
    specialise ScEnv
    env CallEnv
    seed_calls) [RhsInfo]
    rhs_infos [SpecInfo]
    spec_infos
                ; let ([ScUsage]
    extra_usg_s, [SpecInfo]
    new_spec_infos) = forall a b. [(a, b)] -> ([a], [b])
    unzip [(ScUsage, SpecInfo)]
    specs_w_usg
                      extra_usg :: ScUsage
    extra_usg = [ScUsage] -> ScUsage
    combineUsages [ScUsage]
    extra_usg_s
                      all_usg :: ScUsage
    all_usg   = ScUsage
    usg_so_far ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    extra_usg
                ; Int
    -> CallEnv -> ScUsage -> [SpecInfo] -> UniqSM (ScUsage, [SpecInfo])
    go (Int
    n_iter forall a. Num a => a -> a -> a
    + Int
    1) (ScUsage -> CallEnv
    scu_calls ScUsage
    extra_usg) ScUsage
    all_usg [SpecInfo]
    new_spec_infos }

        -- See Note [Limit recursive specialisation]
        the_limit :: Int
    the_limit = case ScEnv -> Maybe Int
    sc_count ScEnv
    env of
                      Maybe Int
    Nothing  -> Int
    10    -- Ugh!
                      Just Int
    max -> Int
    max

    ----------------------
    specialise
       :: ScEnv
       -> CallEnv                     -- Info on newly-discovered calls to this function
       -> RhsInfo
       -> SpecInfo                    -- Original RHS plus patterns dealt with
       -> UniqSM (ScUsage, SpecInfo)  -- New specialised versions and their usage

    -- See Note [spec_usg includes rhs_usg]

    -- Note: this only generates *specialised* bindings
    -- The original binding is added by ruleInfoBinds
    --
    -- Note: the rhs here is the optimised version of the original rhs
    -- So when we make a specialised copy of the RHS, we're starting
    -- from an RHS whose nested functions have been optimised already.

    specialise :: ScEnv
    -> CallEnv -> RhsInfo -> SpecInfo -> UniqSM (ScUsage, SpecInfo)
    specialise ScEnv
    env CallEnv
    bind_calls (RI { ri_fn :: RhsInfo -> Id
    ri_fn = Id
    fn, ri_lam_bndrs :: RhsInfo -> [Id]
    ri_lam_bndrs = [Id]
    arg_bndrs
                                  , ri_lam_body :: RhsInfo -> Expr Id
    ri_lam_body = Expr Id
    body, ri_arg_occs :: RhsInfo -> [ArgOcc]
    ri_arg_occs = [ArgOcc]
    arg_occs })
                   spec_info :: SpecInfo
    spec_info@(SI { si_specs :: SpecInfo -> [OneSpec]
    si_specs = [OneSpec]
    specs, si_n_specs :: SpecInfo -> Int
    si_n_specs = Int
    spec_count
                                 , si_mb_unspec :: SpecInfo -> Maybe ScUsage
    si_mb_unspec = Maybe ScUsage
    mb_unspec })
      | Id -> Bool
    isDeadEndId Id
    fn  -- Note [Do not specialise diverging functions]
                        -- and do not generate specialisation seeds from its RHS
      = -- pprTrace "specialise bot" (ppr fn) $
        forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, SpecInfo
    spec_info)

      | Activation -> Bool
    isNeverActive (Id -> Activation
    idInlineActivation Id
    fn) -- See Note [Transfer activation]
        Bool -> Bool -> Bool
    || forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [Id]
    arg_bndrs                     -- Only specialise functions
      = -- pprTrace "specialise inactive" (ppr fn) $
        case Maybe ScUsage
    mb_unspec of    -- Behave as if there was a single, boring call
          Just ScUsage
    rhs_usg -> forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    rhs_usg, SpecInfo
    spec_info { si_mb_unspec :: Maybe ScUsage
    si_mb_unspec = forall a. Maybe a
    Nothing })
                             -- See Note [spec_usg includes rhs_usg]
          Maybe ScUsage
    Nothing      -> forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, SpecInfo
    spec_info)

      | Just [Call]
    all_calls <- forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv CallEnv
    bind_calls Id
    fn
      = -- pprTrace "specialise entry {" (ppr fn <+> ppr all_calls) $
        do  { (Bool
    boring_call, [CallPat]
    new_pats) <- ScEnv
    -> Id -> SpecInfo -> [ArgOcc] -> [Call] -> UniqSM (Bool, [CallPat])
    callsToNewPats ScEnv
    env Id
    fn SpecInfo
    spec_info [ArgOcc]
    arg_occs [Call]
    all_calls

            ; let n_pats :: Int
    n_pats = forall (t :: * -> *) a. Foldable t => t a -> Int
    length [CallPat]
    new_pats
    --        ; if (not (null new_pats) || isJust mb_unspec) then
    --            pprTrace "specialise" (vcat [ ppr fn <+> text "with" <+> int n_pats <+> text "good patterns"
    --                                        , text "mb_unspec" <+> ppr (isJust mb_unspec)
    --                                        , text "arg_occs" <+> ppr arg_occs
    --                                        , text "good pats" <+> ppr new_pats])  $
    --               return ()
    --          else return ()

            ; let spec_env :: ScEnv
    spec_env = ScEnv -> Int -> ScEnv
    decreaseSpecCount ScEnv
    env Int
    n_pats
            ; ([ScUsage]
    spec_usgs, [OneSpec]
    new_specs) <- forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> m (b, c)) -> [a] -> m ([b], [c])
    mapAndUnzipM (ScEnv
    -> Id
    -> [Id]
    -> Expr Id
    -> (CallPat, Int)
    -> UniqSM (ScUsage, OneSpec)
    spec_one ScEnv
    spec_env Id
    fn [Id]
    arg_bndrs Expr Id
    body)
                                                     ([CallPat]
    new_pats forall a b. [a] -> [b] -> [(a, b)]
    `zip` [Int
    spec_count..])
                    -- See Note [Specialise original body]

            ; let spec_usg :: ScUsage
    spec_usg = [ScUsage] -> ScUsage
    combineUsages [ScUsage]
    spec_usgs

                  -- If there were any boring calls among the seeds (= all_calls), then those
                  -- calls will call the un-specialised function.  So we should use the seeds
                  -- from the _unspecialised_ function's RHS, which are in mb_unspec, by returning
                  -- then in new_usg.
                  (ScUsage
    new_usg, Maybe ScUsage
    mb_unspec')
                      = case Maybe ScUsage
    mb_unspec of
                          Just ScUsage
    rhs_usg | Bool
    boring_call -> (ScUsage
    spec_usg ScUsage -> ScUsage -> ScUsage
    `combineUsage` ScUsage
    rhs_usg, forall a. Maybe a
    Nothing)
                          Maybe ScUsage
    _                          -> (ScUsage
    spec_usg,                      Maybe ScUsage
    mb_unspec)

    --        ; pprTrace "specialise return }"
    --             (vcat [ ppr fn
    --                   , text "boring_call:" <+> ppr boring_call
    --                   , text "new calls:" <+> ppr (scu_calls new_usg)]) $
    --          return ()

              ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    new_usg, SI { si_specs :: [OneSpec]
    si_specs = [OneSpec]
    new_specs forall a. [a] -> [a] -> [a]
    ++ [OneSpec]
    specs
                                    , si_n_specs :: Int
    si_n_specs = Int
    spec_count forall a. Num a => a -> a -> a
    + Int
    n_pats
                                    , si_mb_unspec :: Maybe ScUsage
    si_mb_unspec = Maybe ScUsage
    mb_unspec' }) }

      | Bool
    otherwise  -- No new seeds, so return nullUsage
      = forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    nullUsage, SpecInfo
    spec_info)

    ---------------------
    spec_one :: ScEnv
             -> OutId       -- Function
             -> [InVar]     -- Lambda-binders of RHS; should match patterns
             -> InExpr      -- Body of the original function
             -> (CallPat, Int)
             -> UniqSM (ScUsage, OneSpec)   -- Rule and binding

    -- spec_one creates a specialised copy of the function, together
    -- with a rule for using it.  I'm very proud of how short this
    -- function is, considering what it does :-).

    {-
      Example

         In-scope: a, x::a
         f = /\b \y::[(a,b)] -> ....f (b,c) ((:) (a,(b,c)) (x,v) (h w))...
              [c::*, v::(b,c) are presumably bound by the (...) part]
      ==>
         f_spec = /\ b c \ v::(b,c) hw::[(a,(b,c))] ->
                      (...entire body of f...) [b -> (b,c),
                                                y -> ((:) (a,(b,c)) (x,v) hw)]

         RULE:  forall b::* c::*,           -- Note, *not* forall a, x
                       v::(b,c),
                       hw::[(a,(b,c))] .

                f (b,c) ((:) (a,(b,c)) (x,v) hw) = f_spec b c v hw
    -}

    spec_one :: ScEnv
    -> Id
    -> [Id]
    -> Expr Id
    -> (CallPat, Int)
    -> UniqSM (ScUsage, OneSpec)
    spec_one ScEnv
    env Id
    fn [Id]
    arg_bndrs Expr Id
    body (call_pat :: CallPat
    call_pat@([Id]
    qvars, [Expr Id]
    pats), Int
    rule_number)
      = do  { Unique
    spec_uniq <- forall (m :: * -> *). MonadUnique m => m Unique
    getUniqueM
            ; let spec_env :: ScEnv
    spec_env   = ScEnv -> [(Id, Expr Id)] -> ScEnv
    extendScSubstList (ScEnv -> [Id] -> ScEnv
    extendScInScope ScEnv
    env [Id]
    qvars)
                                                 ([Id]
    arg_bndrs forall a b. [a] -> [b] -> [(a, b)]
    `zip` [Expr Id]
    pats)
                  fn_name :: Name
    fn_name    = Id -> Name
    idName Id
    fn
                  fn_loc :: SrcSpan
    fn_loc     = Name -> SrcSpan
    nameSrcSpan Name
    fn_name
                  fn_occ :: OccName
    fn_occ     = Name -> OccName
    nameOccName Name
    fn_name
                  spec_occ :: OccName
    spec_occ   = OccName -> OccName
    mkSpecOcc OccName
    fn_occ
                  -- We use fn_occ rather than fn in the rule_name string
                  -- as we don't want the uniq to end up in the rule, and
                  -- hence in the ABI, as that can cause spurious ABI
                  -- changes (#4012).
                  rule_name :: FastString
    rule_name  = String -> FastString
    mkFastString (String
    "SC:" forall a. [a] -> [a] -> [a]
    ++ OccName -> String
    occNameString OccName
    fn_occ forall a. [a] -> [a] -> [a]
    ++ forall a. Show a => a -> String
    show Int
    rule_number)
                  spec_name :: Name
    spec_name  = Unique -> OccName -> SrcSpan -> Name
    mkInternalName Unique
    spec_uniq OccName
    spec_occ SrcSpan
    fn_loc
    --      ; pprTrace "{spec_one" (ppr (sc_count env) <+> ppr fn
    --                              <+> ppr pats <+> text "-->" <+> ppr spec_name) $
    --        return ()

            -- Specialise the body
            ; (ScUsage
    spec_usg, Expr Id
    spec_body) <- ScEnv -> Expr Id -> UniqSM (ScUsage, Expr Id)
    scExpr ScEnv
    spec_env Expr Id
    body

    --      ; pprTrace "done spec_one}" (ppr fn) $
    --        return ()

                    -- And build the results
            ; let ([Id]
    spec_lam_args, [Id]
    spec_call_args) = DynFlags -> [Id] -> Type -> ([Id], [Id])
    mkWorkerArgs (ScEnv -> DynFlags
    sc_dflags ScEnv
    env)
                                                                 [Id]
    qvars Type
    body_ty
                    -- Usual w/w hack to avoid generating
                    -- a spec_rhs of unlifted type and no args

                  spec_lam_args_str :: [Id]
    spec_lam_args_str = [Demand] -> [Id] -> [Id]
    handOutStrictnessInformation (forall a b. (a, b) -> a
    fst (StrictSig -> ([Demand], Divergence)
    splitStrictSig StrictSig
    spec_str)) [Id]
    spec_lam_args
                    -- Annotate the variables with the strictness information from
                    -- the function (see Note [Strictness information in worker binders])

                  spec_join_arity :: Maybe Int
    spec_join_arity | Id -> Bool
    isJoinId Id
    fn = forall a. a -> Maybe a
    Just (forall (t :: * -> *) a. Foldable t => t a -> Int
    length [Id]
    spec_lam_args)
                                  | Bool
    otherwise   = forall a. Maybe a
    Nothing
                  spec_id :: Id
    spec_id    = HasDebugCallStack => Name -> Type -> Type -> Id
    mkLocalId Name
    spec_name Type
    Many
                                         ([Id] -> Type -> Type
    mkLamTypes [Id]
    spec_lam_args Type
    body_ty)
                                 -- See Note [Transfer strictness]
                                 Id -> StrictSig -> Id
    `setIdStrictness` StrictSig
    spec_str
                                 Id -> CprSig -> Id
    `setIdCprInfo` CprSig
    topCprSig
                                 Id -> Int -> Id
    `setIdArity` forall a. (a -> Bool) -> [a] -> Int
    count Id -> Bool
    isId [Id]
    spec_lam_args
                                 Id -> Maybe Int -> Id
    `asJoinId_maybe` Maybe Int
    spec_join_arity
                  spec_str :: StrictSig
    spec_str   = Id -> [Id] -> [Expr Id] -> StrictSig
    calcSpecStrictness Id
    fn [Id]
    spec_lam_args [Expr Id]
    pats

                    -- Conditionally use result of new worker-wrapper transform
                  spec_rhs :: Expr Id
    spec_rhs   = forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    spec_lam_args_str Expr Id
    spec_body
                  body_ty :: Type
    body_ty    = Expr Id -> Type
    exprType Expr Id
    spec_body
                  rule_rhs :: Expr Id
    rule_rhs   = forall b. Expr b -> [Id] -> Expr b
    mkVarApps (forall b. Id -> Expr b
    Var Id
    spec_id) [Id]
    spec_call_args
                  inline_act :: Activation
    inline_act = Id -> Activation
    idInlineActivation Id
    fn
                  this_mod :: Module
    this_mod   = ScEnv -> Module
    sc_module ScEnv
    spec_env
                  rule :: CoreRule
    rule       = Module
    -> Bool
    -> Bool
    -> FastString
    -> Activation
    -> Name
    -> [Id]
    -> [Expr Id]
    -> Expr Id
    -> CoreRule
    mkRule Module
    this_mod Bool
    True {- Auto -} Bool
    True {- Local -}
                                      FastString
    rule_name Activation
    inline_act Name
    fn_name [Id]
    qvars [Expr Id]
    pats Expr Id
    rule_rhs
                               -- See Note [Transfer activation]
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (ScUsage
    spec_usg, OS { os_pat :: CallPat
    os_pat = CallPat
    call_pat, os_rule :: CoreRule
    os_rule = CoreRule
    rule
                                   , os_id :: Id
    os_id = Id
    spec_id
                                   , os_rhs :: Expr Id
    os_rhs = Expr Id
    spec_rhs }) }

    -- See Note [Strictness information in worker binders]
    handOutStrictnessInformation :: [Demand] -> [Var] -> [Var]
    handOutStrictnessInformation :: [Demand] -> [Id] -> [Id]
    handOutStrictnessInformation = [Demand] -> [Id] -> [Id]
    go
      where
        go :: [Demand] -> [Id] -> [Id]
    go [Demand]
    _ [] = []
        go [] [Id]
    vs = [Id]
    vs
        go (Demand
    d:[Demand]
    dmds) (Id
    v:[Id]
    vs) | Id -> Bool
    isId Id
    v = Id -> Demand -> Id
    setIdDemandInfo Id
    v Demand
    d forall a. a -> [a] -> [a]
    : [Demand] -> [Id] -> [Id]
    go [Demand]
    dmds [Id]
    vs
        go [Demand]
    dmds (Id
    v:[Id]
    vs) = Id
    v forall a. a -> [a] -> [a]
    : [Demand] -> [Id] -> [Id]
    go [Demand]
    dmds [Id]
    vs

    calcSpecStrictness :: Id                     -- The original function
                       -> [Var] -> [CoreExpr]    -- Call pattern
                       -> StrictSig              -- Strictness of specialised thing
    -- See Note [Transfer strictness]
    calcSpecStrictness :: Id -> [Id] -> [Expr Id] -> StrictSig
    calcSpecStrictness Id
    fn [Id]
    qvars [Expr Id]
    pats
      = [Demand] -> Divergence -> StrictSig
    mkClosedStrictSig [Demand]
    spec_dmds Divergence
    div
      where
        spec_dmds :: [Demand]
    spec_dmds = [ forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv DmdEnv
    dmd_env Id
    qv forall a. Maybe a -> a -> a
    `orElse` Demand
    topDmd | Id
    qv <- [Id]
    qvars, Id -> Bool
    isId Id
    qv ]
        StrictSig (DmdType DmdEnv
    _ [Demand]
    dmds Divergence
    div) = Id -> StrictSig
    idStrictness Id
    fn

        dmd_env :: DmdEnv
    dmd_env = DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go forall a. VarEnv a
    emptyVarEnv [Demand]
    dmds [Expr Id]
    pats

        go :: DmdEnv -> [Demand] -> [CoreExpr] -> DmdEnv
        go :: DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go DmdEnv
    env [Demand]
    ds (Type {} : [Expr Id]
    pats)     = DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go DmdEnv
    env [Demand]
    ds [Expr Id]
    pats
        go DmdEnv
    env [Demand]
    ds (Coercion {} : [Expr Id]
    pats) = DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go DmdEnv
    env [Demand]
    ds [Expr Id]
    pats
        go DmdEnv
    env (Demand
    d:[Demand]
    ds) (Expr Id
    pat : [Expr Id]
    pats)     = DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go (DmdEnv -> Demand -> Expr Id -> DmdEnv
    go_one DmdEnv
    env Demand
    d Expr Id
    pat) [Demand]
    ds [Expr Id]
    pats
        go DmdEnv
    env [Demand]
    _      [Expr Id]
    _                = DmdEnv
    env

        go_one :: DmdEnv -> Demand -> CoreExpr -> DmdEnv
        go_one :: DmdEnv -> Demand -> Expr Id -> DmdEnv
    go_one DmdEnv
    env Demand
    d          (Var Id
    v) = forall a. (a -> a -> a) -> VarEnv a -> Id -> a -> VarEnv a
    extendVarEnv_C Demand -> Demand -> Demand
    plusDmd DmdEnv
    env Id
    v Demand
    d
        go_one DmdEnv
    env (Card
    _n :* SubDemand
    cd) Expr Id
    e -- NB: _n does not have to be strict
          | (Var Id
    _, [Expr Id]
    args) <- forall b. Expr b -> (Expr b, [Expr b])
    collectArgs Expr Id
    e
          , Just [Demand]
    ds <- Int -> SubDemand -> Maybe [Demand]
    viewProd (forall (t :: * -> *) a. Foldable t => t a -> Int
    length [Expr Id]
    args) SubDemand
    cd
          = DmdEnv -> [Demand] -> [Expr Id] -> DmdEnv
    go DmdEnv
    env [Demand]
    ds [Expr Id]
    args
        go_one DmdEnv
    env Demand
    _               Expr Id
    _       = DmdEnv
    env

    {-
    Note [spec_usg includes rhs_usg]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In calls to 'specialise', the returned ScUsage must include the rhs_usg in
    the passed-in SpecInfo, unless there are no calls at all to the function.

    The caller can, indeed must, assume this.  They should not combine in rhs_usg
    themselves, or they'll get rhs_usg twice -- and that can lead to an exponential
    blowup of duplicates in the CallEnv.  This is what gave rise to the massive
    performance loss in #8852.

    Note [Specialise original body]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The RhsInfo for a binding keeps the *original* body of the binding.  We
    must specialise that, *not* the result of applying specExpr to the RHS
    (which is also kept in RhsInfo). Otherwise we end up specialising a
    specialised RHS, and that can lead directly to exponential behaviour.

    Note [Transfer activation]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~
      This note is for SpecConstr, but exactly the same thing
      happens in the overloading specialiser; see
      Note [Auto-specialisation and RULES] in GHC.Core.Opt.Specialise.

    In which phase should the specialise-constructor rules be active?
    Originally I made them always-active, but Manuel found that this
    defeated some clever user-written rules.  Then I made them active only
    in FinalPhase; after all, currently, the specConstr transformation is
    only run after the simplifier has reached FinalPhase, but that meant
    that specialisations didn't fire inside wrappers; see test
    simplCore/should_compile/spec-inline.

    So now I just use the inline-activation of the parent Id, as the
    activation for the specialisation RULE, just like the main specialiser;

    This in turn means there is no point in specialising NOINLINE things,
    so we test for that.

    Note [Transfer strictness]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~
    We must transfer strictness information from the original function to
    the specialised one.  Suppose, for example

      f has strictness     SSx
            and a RULE     f (a:as) b = f_spec a as b

    Now we want f_spec to have strictness  LLSx, otherwise we'll use call-by-need
    when calling f_spec instead of call-by-value.  And that can result in
    unbounded worsening in space (cf the classic foldl vs foldl')

    See #3437 for a good example.

    The function calcSpecStrictness performs the calculation.

    Note [Strictness information in worker binders]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    After having calculated the strictness annotation for the worker (see Note
    [Transfer strictness] above), we also want to have this information attached to
    the worker’s arguments, for the benefit of later passes. The function
    handOutStrictnessInformation decomposes the strictness annotation calculated by
    calcSpecStrictness and attaches them to the variables.

    ************************************************************************
    *                                                                      *
    \subsection{Argument analysis}
    *                                                                      *
    ************************************************************************

    This code deals with analysing call-site arguments to see whether
    they are constructor applications.

    Note [Free type variables of the qvar types]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In a call (f @a x True), that we want to specialise, what variables should
    we quantify over.  Clearly over 'a' and 'x', but what about any type variables
    free in x's type?  In fact we don't need to worry about them because (f @a)
    can only be a well-typed application if its type is compatible with x, so any
    variables free in x's type must be free in (f @a), and hence either be gathered
    via 'a' itself, or be in scope at f's defn.  Hence we just take
      (exprsFreeVars pats).

    BUT phantom type synonyms can mess this reasoning up,
      eg   x::T b   with  type T b = Int
    So we apply expandTypeSynonyms to the bound Ids.
    See # 5458.  Yuk.

    Note [SpecConstr call patterns]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    A "call patterns" that we collect is going to become the LHS of a RULE.
    It's important that it doesn't have
         e |> Refl
    or
        e |> g1 |> g2
    because both of these will be optimised by Simplify.simplRule. In the
    former case such optimisation benign, because the rule will match more
    terms; but in the latter we may lose a binding of 'g1' or 'g2', and
    end up with a rule LHS that doesn't bind the template variables
    (#10602).

    The simplifier eliminates such things, but SpecConstr itself constructs
    new terms by substituting.  So the 'mkCast' in the Cast case of scExpr
    is very important!

    Note [Choosing patterns]
    ~~~~~~~~~~~~~~~~~~~~~~~~
    If we get lots of patterns we may not want to make a specialisation
    for each of them (code bloat), so we choose as follows, implemented
    by trim_pats.

    * The flag -fspec-constr-count-N sets the sc_count field
      of the ScEnv to (Just n).  This limits the total number
      of specialisations for a given function to N.

    * -fno-spec-constr-count sets the sc_count field to Nothing,
      which switches of the limit.

    * The ghastly ForceSpecConstr trick also switches of the limit
      for a particular function

    * Otherwise we sort the patterns to choose the most general
      ones first; more general => more widely applicable.

    Note [SpecConstr and casts]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider (#14270) a call like

        let f = e
        in ... f (K @(a |> co)) ...

    where 'co' is a coercion variable not in scope at f's definition site.
    If we aren't caereful we'll get

        let $sf a co = e (K @(a |> co))
            RULE "SC:f" forall a co.  f (K @(a |> co)) = $sf a co
            f = e
        in ...

    But alas, when we match the call we won't bind 'co', because type-matching
    (for good reasons) discards casts).

    I don't know how to solve this, so for now I'm just discarding any
    call patterns that
      * Mentions a coercion variable in a type argument
      * That is not in scope at the binding of the function

    I think this is very rare.

    It is important (e.g. #14936) that this /only/ applies to
    coercions mentioned in casts.  We don't want to be discombobulated
    by casts in terms!  For example, consider
       f ((e1,e2) |> sym co)
    where, say,
       f  :: Foo -> blah
       co :: Foo ~R (Int,Int)

    Here we definitely do want to specialise for that pair!  We do not
    match on the structure of the coercion; instead we just match on a
    coercion variable, so the RULE looks like

       forall (x::Int, y::Int, co :: (Int,Int) ~R Foo)
         f ((x,y) |> co) = $sf x y co

    Often the body of f looks like
       f arg = ...(case arg |> co' of
                    (x,y) -> blah)...

    so that the specialised f will turn into
       $sf x y co = let arg = (x,y) |> co
                    in ...(case arg>| co' of
                             (x,y) -> blah)....

    which will simplify to not use 'co' at all.  But we can't guarantee
    that co will end up unused, so we still pass it.  Absence analysis
    may remove it later.

    Note that this /also/ discards the call pattern if we have a cast in a
    /term/, although in fact Rules.match does make a very flaky and
    fragile attempt to match coercions.  e.g. a call like
        f (Maybe Age) (Nothing |> co) blah
        where co :: Maybe Int ~ Maybe Age
    will be discarded.  It's extremely fragile to match on the form of a
    coercion, so I think it's better just not to try.  A more complicated
    alternative would be to discard calls that mention coercion variables
    only in kind-casts, but I'm doing the simple thing for now.
    -}

    type CallPat = ([Var], [CoreExpr])      -- Quantified variables and arguments
                                            -- See Note [SpecConstr call patterns]

    callsToNewPats :: ScEnv -> Id
                   -> SpecInfo
                   -> [ArgOcc] -> [Call]
                   -> UniqSM (Bool, [CallPat])
            -- Result has no duplicate patterns,
            -- nor ones mentioned in done_pats
            -- Bool indicates that there was at least one boring pattern
    callsToNewPats :: ScEnv
    -> Id -> SpecInfo -> [ArgOcc] -> [Call] -> UniqSM (Bool, [CallPat])
    callsToNewPats ScEnv
    env Id
    fn spec_info :: SpecInfo
    spec_info@(SI { si_specs :: SpecInfo -> [OneSpec]
    si_specs = [OneSpec]
    done_specs }) [ArgOcc]
    bndr_occs [Call]
    calls
      = do  { [Maybe CallPat]
    mb_pats <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM (ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat)
    callToPats ScEnv
    env [ArgOcc]
    bndr_occs) [Call]
    calls

            ; let have_boring_call :: Bool
    have_boring_call = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any forall a. Maybe a -> Bool
    isNothing [Maybe CallPat]
    mb_pats

                  good_pats :: [CallPat]
                  good_pats :: [CallPat]
    good_pats = forall a. [Maybe a] -> [a]
    catMaybes [Maybe CallPat]
    mb_pats

                  -- Remove patterns we have already done
                  new_pats :: [CallPat]
    new_pats = forall a. (a -> Bool) -> [a] -> [a]
    filterOut CallPat -> Bool
    is_done [CallPat]
    good_pats
                  is_done :: CallPat -> Bool
    is_done CallPat
    p = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any (CallPat -> CallPat -> Bool
    samePat CallPat
    p forall b c a. (b -> c) -> (a -> b) -> a -> c
    . OneSpec -> CallPat
    os_pat) [OneSpec]
    done_specs

                  -- Remove duplicates
                  non_dups :: [CallPat]
    non_dups = forall a. (a -> a -> Bool) -> [a] -> [a]
    nubBy CallPat -> CallPat -> Bool
    samePat [CallPat]
    new_pats

                  -- Remove ones that have too many worker variables
                  small_pats :: [CallPat]
    small_pats = forall a. (a -> Bool) -> [a] -> [a]
    filterOut CallPat -> Bool
    too_big [CallPat]
    non_dups
                  too_big :: CallPat -> Bool
    too_big ([Id]
    vars,[Expr Id]
    args) = Bool -> Bool
    not (DynFlags -> Int -> [Id] -> Bool
    isWorkerSmallEnough (ScEnv -> DynFlags
    sc_dflags ScEnv
    env) (forall b. [Arg b] -> Int
    valArgCount [Expr Id]
    args) [Id]
    vars)
                      -- We are about to construct w/w pair in 'spec_one'.
                      -- Omit specialisation leading to high arity workers.
                      -- See Note [Limit w/w arity] in GHC.Core.Opt.WorkWrap.Utils

                    -- Discard specialisations if there are too many of them
                  trimmed_pats :: [CallPat]
    trimmed_pats = ScEnv -> Id -> SpecInfo -> [CallPat] -> [CallPat]
    trim_pats ScEnv
    env Id
    fn SpecInfo
    spec_info [CallPat]
    small_pats

    --        ; pprTrace "callsToPats" (vcat [ text "calls to" <+> ppr fn <> colon <+> ppr calls
    --                                       , text "done_specs:" <+> ppr (map os_pat done_specs)
    --                                       , text "good_pats:" <+> ppr good_pats ]) $
    --          return ()

            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    have_boring_call, [CallPat]
    trimmed_pats) }

    trim_pats :: ScEnv -> Id -> SpecInfo -> [CallPat] -> [CallPat]
    -- See Note [Choosing patterns]
    trim_pats :: ScEnv -> Id -> SpecInfo -> [CallPat] -> [CallPat]
    trim_pats ScEnv
    env Id
    fn (SI { si_n_specs :: SpecInfo -> Int
    si_n_specs = Int
    done_spec_count }) [CallPat]
    pats
      | ScEnv -> Bool
    sc_force ScEnv
    env
        Bool -> Bool -> Bool
    || forall a. Maybe a -> Bool
    isNothing Maybe Int
    mb_scc
        Bool -> Bool -> Bool
    || Int
    n_remaining forall a. Ord a => a -> a -> Bool
    >= Int
    n_pats
      = -- pprTrace "trim_pats: no-trim" (ppr (sc_force env) $$ ppr mb_scc $$ ppr n_remaining $$ ppr n_pats)
        [CallPat]
    pats          -- No need to trim

      | Bool
    otherwise
      = [CallPat] -> [CallPat]
    emit_trace forall a b. (a -> b) -> a -> b
    $  -- Need to trim, so keep the best ones
        forall a. Int -> [a] -> [a]
    take Int
    n_remaining [CallPat]
    sorted_pats

      where
        n_pats :: Int
    n_pats         = forall (t :: * -> *) a. Foldable t => t a -> Int
    length [CallPat]
    pats
        spec_count' :: Int
    spec_count'    = Int
    n_pats forall a. Num a => a -> a -> a
    + Int
    done_spec_count
        n_remaining :: Int
    n_remaining    = Int
    max_specs forall a. Num a => a -> a -> a
    - Int
    done_spec_count
        mb_scc :: Maybe Int
    mb_scc         = ScEnv -> Maybe Int
    sc_count ScEnv
    env
        Just Int
    max_specs = Maybe Int
    mb_scc

        sorted_pats :: [CallPat]
    sorted_pats = forall a b. (a -> b) -> [a] -> [b]
    map forall a b. (a, b) -> a
    fst forall a b. (a -> b) -> a -> b
    $
                      forall a. (a -> a -> Ordering) -> [a] -> [a]
    sortBy (forall a b. Ord a => (b -> a) -> b -> b -> Ordering
    comparing forall a b. (a, b) -> b
    snd) forall a b. (a -> b) -> a -> b
    $
                      [(CallPat
    pat, CallPat -> Int
    pat_cons CallPat
    pat) | CallPat
    pat <- [CallPat]
    pats]
         -- Sort in order of increasing number of constructors
         -- (i.e. decreasing generality) and pick the initial
         -- segment of this list

        pat_cons :: CallPat -> Int
        -- How many data constructors of literals are in
        -- the pattern.  More data-cons => less general
        pat_cons :: CallPat -> Int
    pat_cons ([Id]
    qs, [Expr Id]
    ps) = forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr (forall a. Num a => a -> a -> a
    (+) forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Expr Id -> Int
    n_cons) Int
    0 [Expr Id]
    ps
           where
              q_set :: CoVarSet
    q_set = [Id] -> CoVarSet
    mkVarSet [Id]
    qs
              n_cons :: Expr Id -> Int
    n_cons (Var Id
    v) | Id
    v Id -> CoVarSet -> Bool
    `elemVarSet` CoVarSet
    q_set = Int
    0
                             | Bool
    otherwise            = Int
    1
              n_cons (Cast Expr Id
    e Coercion
    _)  = Expr Id -> Int
    n_cons Expr Id
    e
              n_cons (App Expr Id
    e1 Expr Id
    e2) = Expr Id -> Int
    n_cons Expr Id
    e1 forall a. Num a => a -> a -> a
    + Expr Id -> Int
    n_cons Expr Id
    e2
              n_cons (Lit {})    = Int
    1
              n_cons Expr Id
    _           = Int
    0

        emit_trace :: [CallPat] -> [CallPat]
    emit_trace [CallPat]
    result
           | Bool
    debugIsOn Bool -> Bool -> Bool
    || DynFlags -> Bool
    hasPprDebug (ScEnv -> DynFlags
    sc_dflags ScEnv
    env)
             -- Suppress this scary message for ordinary users!  #5125
           = forall a. String -> SDoc -> a -> a
    pprTrace String
    "SpecConstr" SDoc
    msg [CallPat]
    result
           | Bool
    otherwise
           = [CallPat]
    result
        msg :: SDoc
    msg = [SDoc] -> SDoc
    vcat [ [SDoc] -> SDoc
    sep [ String -> SDoc
    text String
    "Function" SDoc -> SDoc -> SDoc
    <+> SDoc -> SDoc
    quotes (forall a. Outputable a => a -> SDoc
    ppr Id
    fn)
                         , Int -> SDoc -> SDoc
    nest Int
    2 (String -> SDoc
    text String
    "has" SDoc -> SDoc -> SDoc
    <+>
                                   Int -> SDoc -> SDoc
    speakNOf Int
    spec_count' (String -> SDoc
    text String
    "call pattern") SDoc -> SDoc -> SDoc
    <> SDoc
    comma SDoc -> SDoc -> SDoc
    <+>
                                   String -> SDoc
    text String
    "but the limit is" SDoc -> SDoc -> SDoc
    <+> Int -> SDoc
    int Int
    max_specs) ]
                   , String -> SDoc
    text String
    "Use -fspec-constr-count=n to set the bound"
                   , String -> SDoc
    text String
    "done_spec_count =" SDoc -> SDoc -> SDoc
    <+> Int -> SDoc
    int Int
    done_spec_count
                   , String -> SDoc
    text String
    "Keeping " SDoc -> SDoc -> SDoc
    <+> Int -> SDoc
    int Int
    n_remaining SDoc -> SDoc -> SDoc
    <> String -> SDoc
    text String
    ", out of" SDoc -> SDoc -> SDoc
    <+> Int -> SDoc
    int Int
    n_pats
                   , String -> SDoc
    text String
    "Discarding:" SDoc -> SDoc -> SDoc
    <+> forall a. Outputable a => a -> SDoc
    ppr (forall a. Int -> [a] -> [a]
    drop Int
    n_remaining [CallPat]
    sorted_pats) ]

    callToPats :: ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat)
            -- The [Var] is the variables to quantify over in the rule
            --      Type variables come first, since they may scope
            --      over the following term variables
            -- The [CoreExpr] are the argument patterns for the rule
    callToPats :: ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat)
    callToPats ScEnv
    env [ArgOcc]
    bndr_occs call :: Call
    call@(Call Id
    _ [Expr Id]
    args ValueEnv
    con_env)
      | [Expr Id]
    args forall a b. [a] -> [b] -> Bool
    `ltLength` [ArgOcc]
    bndr_occs      -- Check saturated
      = forall (m :: * -> *) a. Monad m => a -> m a
    return forall a. Maybe a
    Nothing
      | Bool
    otherwise
      = do  { let in_scope :: InScopeSet
    in_scope = Subst -> InScopeSet
    substInScope (ScEnv -> Subst
    sc_subst ScEnv
    env)
            ; (Bool
    interesting, [Expr Id]
    pats) <- ScEnv
    -> InScopeSet
    -> ValueEnv
    -> [Expr Id]
    -> [ArgOcc]
    -> UniqSM (Bool, [Expr Id])
    argsToPats ScEnv
    env InScopeSet
    in_scope ValueEnv
    con_env [Expr Id]
    args [ArgOcc]
    bndr_occs
            ; let pat_fvs :: [Id]
    pat_fvs = [Expr Id] -> [Id]
    exprsFreeVarsList [Expr Id]
    pats
                    -- To get determinism we need the list of free variables in
                    -- deterministic order. Otherwise we end up creating
                    -- lambdas with different argument orders. See
                    -- determinism/simplCore/should_compile/spec-inline-determ.hs
                    -- for an example. For explanation of determinism
                    -- considerations See Note [Unique Determinism] in GHC.Types.Unique.

                  in_scope_vars :: CoVarSet
    in_scope_vars = InScopeSet -> CoVarSet
    getInScopeVars InScopeSet
    in_scope
                  is_in_scope :: Id -> Bool
    is_in_scope Id
    v = Id
    v Id -> CoVarSet -> Bool
    `elemVarSet` CoVarSet
    in_scope_vars
                  qvars :: [Id]
    qvars         = forall a. (a -> Bool) -> [a] -> [a]
    filterOut Id -> Bool
    is_in_scope [Id]
    pat_fvs
                    -- Quantify over variables that are not in scope
                    -- at the call site
                    -- See Note [Free type variables of the qvar types]
                    -- See Note [Shadowing] at the top

                  ([Id]
    ktvs, [Id]
    ids)   = forall a. (a -> Bool) -> [a] -> ([a], [a])
    partition Id -> Bool
    isTyVar [Id]
    qvars
                  qvars' :: [Id]
    qvars'        = [Id] -> [Id]
    scopedSort [Id]
    ktvs forall a. [a] -> [a] -> [a]
    ++ forall a b. (a -> b) -> [a] -> [b]
    map Id -> Id
    sanitise [Id]
    ids
                    -- Order into kind variables, type variables, term variables
                    -- The kind of a type variable may mention a kind variable
                    -- and the type of a term variable may mention a type variable

                  sanitise :: Id -> Id
    sanitise Id
    id   = (Type -> Type) -> Id -> Id
    updateIdTypeAndMult Type -> Type
    expandTypeSynonyms Id
    id
                    -- See Note [Free type variables of the qvar types]

                  -- Bad coercion variables: see Note [SpecConstr and casts]
                  bad_covars :: CoVarSet
                  bad_covars :: CoVarSet
    bad_covars = forall a. (a -> CoVarSet) -> [a] -> CoVarSet
    mapUnionVarSet Expr Id -> CoVarSet
    get_bad_covars [Expr Id]
    pats
                  get_bad_covars :: CoreArg -> CoVarSet
                  get_bad_covars :: Expr Id -> CoVarSet
    get_bad_covars (Type Type
    ty)
                    = (Id -> Bool) -> CoVarSet -> CoVarSet
    filterVarSet (\Id
    v -> Id -> Bool
    isId Id
    v Bool -> Bool -> Bool
    && Bool -> Bool
    not (Id -> Bool
    is_in_scope Id
    v)) forall a b. (a -> b) -> a -> b
    $
                      Type -> CoVarSet
    tyCoVarsOfType Type
    ty
                  get_bad_covars Expr Id
    _
                    = CoVarSet
    emptyVarSet

            ; -- pprTrace "callToPats"  (ppr args $$ ppr bndr_occs) $
              WARN( not (isEmptyVarSet bad_covars)
                  , text "SpecConstr: bad covars:" <+> ppr bad_covars
                    $$ ppr call )
              if Bool
    interesting Bool -> Bool -> Bool
    && CoVarSet -> Bool
    isEmptyVarSet CoVarSet
    bad_covars
              then forall (m :: * -> *) a. Monad m => a -> m a
    return (forall a. a -> Maybe a
    Just ([Id]
    qvars', [Expr Id]
    pats))
              else forall (m :: * -> *) a. Monad m => a -> m a
    return forall a. Maybe a
    Nothing }

        -- argToPat takes an actual argument, and returns an abstracted
        -- version, consisting of just the "constructor skeleton" of the
        -- argument, with non-constructor sub-expression replaced by new
        -- placeholder variables.  For example:
        --    C a (D (f x) (g y))  ==>  C p1 (D p2 p3)

    argToPat :: ScEnv
             -> InScopeSet                  -- What's in scope at the fn defn site
             -> ValueEnv                    -- ValueEnv at the call site
             -> CoreArg                     -- A call arg (or component thereof)
             -> ArgOcc
             -> UniqSM (Bool, CoreArg)

    -- Returns (interesting, pat),
    -- where pat is the pattern derived from the argument
    --            interesting=True if the pattern is non-trivial (not a variable or type)
    -- E.g.         x:xs         --> (True, x:xs)
    --              f xs         --> (False, w)        where w is a fresh wildcard
    --              (f xs, 'c')  --> (True, (w, 'c'))  where w is a fresh wildcard
    --              \x. x+y      --> (True, \x. x+y)
    --              lvl7         --> (True, lvl7)      if lvl7 is bound
    --                                                 somewhere further out

    argToPat :: ScEnv
    -> InScopeSet
    -> ValueEnv
    -> Expr Id
    -> ArgOcc
    -> UniqSM (Bool, Expr Id)
    argToPat ScEnv
    _env InScopeSet
    _in_scope ValueEnv
    _val_env arg :: Expr Id
    arg@(Type {}) ArgOcc
    _arg_occ
      = forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    False, Expr Id
    arg)

    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env (Tick CoreTickish
    _ Expr Id
    arg) ArgOcc
    arg_occ
      = ScEnv
    -> InScopeSet
    -> ValueEnv
    -> Expr Id
    -> ArgOcc
    -> UniqSM (Bool, Expr Id)
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env Expr Id
    arg ArgOcc
    arg_occ
            -- Note [Tick annotations in call patterns]
            -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            -- Ignore Notes.  In particular, we want to ignore any InlineMe notes
            -- Perhaps we should not ignore profiling notes, but I'm going to
            -- ride roughshod over them all for now.
            --- See Note [Tick annotations in RULE matching] in GHC.Core.Rules

    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env (Let CoreBind
    _ Expr Id
    arg) ArgOcc
    arg_occ
      = ScEnv
    -> InScopeSet
    -> ValueEnv
    -> Expr Id
    -> ArgOcc
    -> UniqSM (Bool, Expr Id)
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env Expr Id
    arg ArgOcc
    arg_occ
            -- See Note [Matching lets] in "GHC.Core.Rules"
            -- Look through let expressions
            -- e.g.         f (let v = rhs in (v,w))
            -- Here we can specialise for f (v,w)
            -- because the rule-matcher will look through the let.

    {- Disabled; see Note [Matching cases] in "GHC.Core.Rules"
    argToPat env in_scope val_env (Case scrut _ _ [(_, _, rhs)]) arg_occ
      | exprOkForSpeculation scrut  -- See Note [Matching cases] in "GHC.Core.Rules"
      = argToPat env in_scope val_env rhs arg_occ
    -}

    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env (Cast Expr Id
    arg Coercion
    co) ArgOcc
    arg_occ
      | Bool -> Bool
    not (ScEnv -> Type -> Bool
    ignoreType ScEnv
    env Type
    ty2)
      = do  { (Bool
    interesting, Expr Id
    arg') <- ScEnv
    -> InScopeSet
    -> ValueEnv
    -> Expr Id
    -> ArgOcc
    -> UniqSM (Bool, Expr Id)
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env Expr Id
    arg ArgOcc
    arg_occ
            ; if Bool -> Bool
    not Bool
    interesting then
                    Type -> UniqSM (Bool, Expr Id)
    wildCardPat Type
    ty2
              else do
            { -- Make a wild-card pattern for the coercion
              Unique
    uniq <- forall (m :: * -> *). MonadUnique m => m Unique
    getUniqueM
            ; let co_name :: Name
    co_name = Unique -> FastString -> Name
    mkSysTvName Unique
    uniq (String -> FastString
    fsLit String
    "sg")
                  co_var :: Id
    co_var  = Name -> Type -> Id
    mkCoVar Name
    co_name (Role -> Type -> Type -> Type
    mkCoercionType Role
    Representational Type
    ty1 Type
    ty2)
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    interesting, forall b. Expr b -> Coercion -> Expr b
    Cast Expr Id
    arg' (Id -> Coercion
    mkCoVarCo Id
    co_var)) } }
      where
        Pair Type
    ty1 Type
    ty2 = Coercion -> Pair Type
    coercionKind Coercion
    co

    {-      Disabling lambda specialisation for now
            It's fragile, and the spec_loop can be infinite
    argToPat in_scope val_env arg arg_occ
      | is_value_lam arg
      = return (True, arg)
      where
        is_value_lam (Lam v e)         -- Spot a value lambda, even if
            | isId v       = True      -- it is inside a type lambda
            | otherwise    = is_value_lam e
        is_value_lam other = False
    -}

      -- Check for a constructor application
      -- NB: this *precedes* the Var case, so that we catch nullary constrs
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env Expr Id
    arg ArgOcc
    arg_occ
      | Just (ConVal (DataAlt DataCon
    dc) [Expr Id]
    args) <- ValueEnv -> Expr Id -> Maybe Value
    isValue ValueEnv
    val_env Expr Id
    arg
      , Bool -> Bool
    not (ScEnv -> DataCon -> Bool
    ignoreDataCon ScEnv
    env DataCon
    dc)        -- See Note [NoSpecConstr]
      , Just [ArgOcc]
    arg_occs <- DataCon -> Maybe [ArgOcc]
    mb_scrut DataCon
    dc
      = do  { let ([Expr Id]
    ty_args, [Expr Id]
    rest_args) = forall b a. [b] -> [a] -> ([a], [a])
    splitAtList (DataCon -> [Id]
    dataConUnivTyVars DataCon
    dc) [Expr Id]
    args
            ; (Bool
    _, [Expr Id]
    args') <- ScEnv
    -> InScopeSet
    -> ValueEnv
    -> [Expr Id]
    -> [ArgOcc]
    -> UniqSM (Bool, [Expr Id])
    argsToPats ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env [Expr Id]
    rest_args [ArgOcc]
    arg_occs
            ; forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    True,
                      forall b. DataCon -> [Arg b] -> Arg b
    mkConApp DataCon
    dc ([Expr Id]
    ty_args forall a. [a] -> [a] -> [a]
    ++ [Expr Id]
    args')) }
      where
        mb_scrut :: DataCon -> Maybe [ArgOcc]
    mb_scrut DataCon
    dc = case ArgOcc
    arg_occ of
                        ScrutOcc DataConEnv [ArgOcc]
    bs | Just [ArgOcc]
    occs <- forall key elt. Uniquable key => UniqFM key elt -> key -> Maybe elt
    lookupUFM DataConEnv [ArgOcc]
    bs DataCon
    dc
                                    -> forall a. a -> Maybe a
    Just ([ArgOcc]
    occs)  -- See Note [Reboxing]
                        ArgOcc
    _other      | ScEnv -> Bool
    sc_force ScEnv
    env Bool -> Bool -> Bool
    || ScEnv -> Bool
    sc_keen ScEnv
    env
                                    -> forall a. a -> Maybe a
    Just (forall a. a -> [a]
    repeat ArgOcc
    UnkOcc)
                                    | Bool
    otherwise
                                    -> forall a. Maybe a
    Nothing

      -- Check if the argument is a variable that
      --    (a) is used in an interesting way in the function body
      --    (b) we know what its value is
      -- In that case it counts as "interesting"
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env (Var Id
    v) ArgOcc
    arg_occ
      | ScEnv -> Bool
    sc_force ScEnv
    env Bool -> Bool -> Bool
    || case ArgOcc
    arg_occ of { ArgOcc
    UnkOcc -> Bool
    False; ArgOcc
    _other -> Bool
    True }, -- (a)
        Bool
    is_value,                                                            -- (b)
           -- Ignoring sc_keen here to avoid gratuitously incurring Note [Reboxing]
           -- So sc_keen focused just on f (I# x), where we have freshly-allocated
           -- box that we can eliminate in the caller
        Bool -> Bool
    not (ScEnv -> Type -> Bool
    ignoreType ScEnv
    env (Id -> Type
    varType Id
    v))
      = forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    True, forall b. Id -> Expr b
    Var Id
    v)
      where
        is_value :: Bool
    is_value
            | Id -> Bool
    isLocalId Id
    v = Id
    v Id -> InScopeSet -> Bool
    `elemInScopeSet` InScopeSet
    in_scope
                            Bool -> Bool -> Bool
    && forall a. Maybe a -> Bool
    isJust (forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv ValueEnv
    val_env Id
    v)
                    -- Local variables have values in val_env
            | Bool
    otherwise   = Unfolding -> Bool
    isValueUnfolding (Id -> Unfolding
    idUnfolding Id
    v)
                    -- Imports have unfoldings

    --      I'm really not sure what this comment means
    --      And by not wild-carding we tend to get forall'd
    --      variables that are in scope, which in turn can
    --      expose the weakness in let-matching
    --      See Note [Matching lets] in GHC.Core.Rules

      -- Check for a variable bound inside the function.
      -- Don't make a wild-card, because we may usefully share
      --    e.g.  f a = let x = ... in f (x,x)
      -- NB: this case follows the lambda and con-app cases!!
    -- argToPat _in_scope _val_env (Var v) _arg_occ
    --   = return (False, Var v)
            -- SLPJ : disabling this to avoid proliferation of versions
            -- also works badly when thinking about seeding the loop
            -- from the body of the let
            --       f x y = letrec g z = ... in g (x,y)
            -- We don't want to specialise for that *particular* x,y

      -- The default case: make a wild-card
      -- We use this for coercions too
    argToPat ScEnv
    _env InScopeSet
    _in_scope ValueEnv
    _val_env Expr Id
    arg ArgOcc
    _arg_occ
      = Type -> UniqSM (Bool, Expr Id)
    wildCardPat (Expr Id -> Type
    exprType Expr Id
    arg)

    wildCardPat :: Type -> UniqSM (Bool, CoreArg)
    wildCardPat :: Type -> UniqSM (Bool, Expr Id)
    wildCardPat Type
    ty
      = do { Unique
    uniq <- forall (m :: * -> *). MonadUnique m => m Unique
    getUniqueM
           ; let id :: Id
    id = FastString -> Unique -> Type -> Type -> Id
    mkSysLocalOrCoVar (String -> FastString
    fsLit String
    "sc") Unique
    uniq Type
    Many Type
    ty
           ; forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool
    False, forall b. Id -> Expr b
    varToCoreExpr Id
    id) }

    argsToPats :: ScEnv -> InScopeSet -> ValueEnv
               -> [CoreArg] -> [ArgOcc]  -- Should be same length
               -> UniqSM (Bool, [CoreArg])
    argsToPats :: ScEnv
    -> InScopeSet
    -> ValueEnv
    -> [Expr Id]
    -> [ArgOcc]
    -> UniqSM (Bool, [Expr Id])
    argsToPats ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env [Expr Id]
    args [ArgOcc]
    occs
      = do { [(Bool, Expr Id)]
    stuff <- forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> b -> m c) -> [a] -> [b] -> m [c]
    zipWithM (ScEnv
    -> InScopeSet
    -> ValueEnv
    -> Expr Id
    -> ArgOcc
    -> UniqSM (Bool, Expr Id)
    argToPat ScEnv
    env InScopeSet
    in_scope ValueEnv
    val_env) [Expr Id]
    args [ArgOcc]
    occs
           ; let ([Bool]
    interesting_s, [Expr Id]
    args') = forall a b. [(a, b)] -> ([a], [b])
    unzip [(Bool, Expr Id)]
    stuff
           ; forall (m :: * -> *) a. Monad m => a -> m a
    return (forall (t :: * -> *). Foldable t => t Bool -> Bool
    or [Bool]
    interesting_s, [Expr Id]
    args') }

    isValue :: ValueEnv -> CoreExpr -> Maybe Value
    isValue :: ValueEnv -> Expr Id -> Maybe Value
    isValue ValueEnv
    _env (Lit Literal
    lit)
      | Literal -> Bool
    litIsLifted Literal
    lit = forall a. Maybe a
    Nothing
      | Bool
    otherwise       = forall a. a -> Maybe a
    Just (AltCon -> [Expr Id] -> Value
    ConVal (Literal -> AltCon
    LitAlt Literal
    lit) [])

    isValue ValueEnv
    env (Var Id
    v)
      | Just Value
    cval <- forall a. VarEnv a -> Id -> Maybe a
    lookupVarEnv ValueEnv
    env Id
    v
      = forall a. a -> Maybe a
    Just Value
    cval  -- You might think we could look in the idUnfolding here
                   -- but that doesn't take account of which branch of a
                   -- case we are in, which is the whole point

      | Bool -> Bool
    not (Id -> Bool
    isLocalId Id
    v) Bool -> Bool -> Bool
    && Unfolding -> Bool
    isCheapUnfolding Unfolding
    unf
      = ValueEnv -> Expr Id -> Maybe Value
    isValue ValueEnv
    env (Unfolding -> Expr Id
    unfoldingTemplate Unfolding
    unf)
      where
        unf :: Unfolding
    unf = Id -> Unfolding
    idUnfolding Id
    v
            -- However we do want to consult the unfolding
            -- as well, for let-bound constructors!

    isValue ValueEnv
    env (Lam Id
    b Expr Id
    e)
      | Id -> Bool
    isTyVar Id
    b = case ValueEnv -> Expr Id -> Maybe Value
    isValue ValueEnv
    env Expr Id
    e of
                      Just Value
    _  -> forall a. a -> Maybe a
    Just Value
    LambdaVal
                      Maybe Value
    Nothing -> forall a. Maybe a
    Nothing
      | Bool
    otherwise = forall a. a -> Maybe a
    Just Value
    LambdaVal

    isValue ValueEnv
    env (Tick CoreTickish
    t Expr Id
    e)
      | Bool -> Bool
    not (forall (pass :: TickishPass). GenTickish pass -> Bool
    tickishIsCode CoreTickish
    t)
      = ValueEnv -> Expr Id -> Maybe Value
    isValue ValueEnv
    env Expr Id
    e

    isValue ValueEnv
    _env Expr Id
    expr       -- Maybe it's a constructor application
      | (Var Id
    fun, [Expr Id]
    args, [CoreTickish]
    _) <- forall b.
    (CoreTickish -> Bool)
    -> Expr b -> (Expr b, [Expr b], [CoreTickish])
    collectArgsTicks (Bool -> Bool
    not forall b c a. (b -> c) -> (a -> b) -> a -> c
    . forall (pass :: TickishPass). GenTickish pass -> Bool
    tickishIsCode) Expr Id
    expr
      = case Id -> Maybe DataCon
    isDataConWorkId_maybe Id
    fun of

            Just DataCon
    con | [Expr Id]
    args forall a. [a] -> Int -> Bool
    `lengthAtLeast` DataCon -> Int
    dataConRepArity DataCon
    con
                    -- Check saturated; might be > because the
                    --                  arity excludes type args
                    -> forall a. a -> Maybe a
    Just (AltCon -> [Expr Id] -> Value
    ConVal (DataCon -> AltCon
    DataAlt DataCon
    con) [Expr Id]
    args)

            Maybe DataCon
    _other | forall b. [Arg b] -> Int
    valArgCount [Expr Id]
    args forall a. Ord a => a -> a -> Bool
    < Id -> Int
    idArity Id
    fun
                    -- Under-applied function
                   -> forall a. a -> Maybe a
    Just Value
    LambdaVal        -- Partial application

            Maybe DataCon
    _other -> forall a. Maybe a
    Nothing

    isValue ValueEnv
    _env Expr Id
    _expr = forall a. Maybe a
    Nothing

    valueIsWorkFree :: Value -> Bool
    valueIsWorkFree :: Value -> Bool
    valueIsWorkFree Value
    LambdaVal       = Bool
    True
    valueIsWorkFree (ConVal AltCon
    _ [Expr Id]
    args) = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    all Expr Id -> Bool
    exprIsWorkFree [Expr Id]
    args

    samePat :: CallPat -> CallPat -> Bool
    samePat :: CallPat -> CallPat -> Bool
    samePat ([Id]
    vs1, [Expr Id]
    as1) ([Id]
    vs2, [Expr Id]
    as2)
      = forall a b. (a -> b -> Bool) -> [a] -> [b] -> Bool
    all2 Expr Id -> Expr Id -> Bool
    same [Expr Id]
    as1 [Expr Id]
    as2
      where
        same :: Expr Id -> Expr Id -> Bool
    same (Var Id
    v1) (Var Id
    v2)
            | Id
    v1 forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
    `elem` [Id]
    vs1 = Id
    v2 forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
    `elem` [Id]
    vs2
            | Id
    v2 forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
    `elem` [Id]
    vs2 = Bool
    False
            | Bool
    otherwise     = Id
    v1 forall a. Eq a => a -> a -> Bool
    == Id
    v2

        same (Lit Literal
    l1)    (Lit Literal
    l2)    = Literal
    l1forall a. Eq a => a -> a -> Bool
    ==Literal
    l2
        same (App Expr Id
    f1 Expr Id
    a1) (App Expr Id
    f2 Expr Id
    a2) = Expr Id -> Expr Id -> Bool
    same Expr Id
    f1 Expr Id
    f2 Bool -> Bool -> Bool
    && Expr Id -> Expr Id -> Bool
    same Expr Id
    a1 Expr Id
    a2

        same (Type {}) (Type {}) = Bool
    True     -- Note [Ignore type differences]
        same (Coercion {}) (Coercion {}) = Bool
    True
        same (Tick CoreTickish
    _ Expr Id
    e1) Expr Id
    e2 = Expr Id -> Expr Id -> Bool
    same Expr Id
    e1 Expr Id
    e2  -- Ignore casts and notes
        same (Cast Expr Id
    e1 Coercion
    _) Expr Id
    e2 = Expr Id -> Expr Id -> Bool
    same Expr Id
    e1 Expr Id
    e2
        same Expr Id
    e1 (Tick CoreTickish
    _ Expr Id
    e2) = Expr Id -> Expr Id -> Bool
    same Expr Id
    e1 Expr Id
    e2
        same Expr Id
    e1 (Cast Expr Id
    e2 Coercion
    _) = Expr Id -> Expr Id -> Bool
    same Expr Id
    e1 Expr Id
    e2

        same Expr Id
    e1 Expr Id
    e2 = WARN( bad e1 || bad e2, ppr e1 $$ ppr e2)
                     Bool
    False  -- Let, lambda, case should not occur
        bad :: Expr b -> Bool
    bad (Case {}) = Bool
    True
        bad (Let {})  = Bool
    True
        bad (Lam {})  = Bool
    True
        bad Expr b
    _other    = Bool
    False

    {-
    Note [Ignore type differences]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    We do not want to generate specialisations where the call patterns
    differ only in their type arguments!  Not only is it utterly useless,
    but it also means that (with polymorphic recursion) we can generate
    an infinite number of specialisations. Example is Data.Sequence.adjustTree,
    I think.
    -}