{-
(c) The AQUA Project, Glasgow University, 1993-1998

\section[Simplify]{The main module of the simplifier}
-}


{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE MultiWayIf #-}

{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
module GHC.Core.Opt.Simplify.Iteration ( simplTopBinds, simplExpr, simplImpRules ) where

import GHC.Prelude

import GHC.Driver.Flags

import GHC.Core
import GHC.Core.Opt.Simplify.Monad
import GHC.Core.Opt.ConstantFold
import GHC.Core.Type hiding ( substCo, substTy, substTyVar, extendTvSubst, extendCvSubst )
import GHC.Core.TyCo.Compare( eqType )
import GHC.Core.Opt.Simplify.Env
import GHC.Core.Opt.Simplify.Inline
import GHC.Core.Opt.Simplify.Utils
import GHC.Core.Opt.OccurAnal ( occurAnalyseExpr, zapLambdaBndrs, scrutOkForBinderSwap, BinderSwapDecision (..) )
import GHC.Core.Make       ( FloatBind, mkImpossibleExpr, castBottomExpr )
import qualified GHC.Core.Make
import GHC.Core.Coercion hiding ( substCo, substCoVar )
import GHC.Core.Reduction
import GHC.Core.Coercion.Opt    ( optCoercion )
import GHC.Core.FamInstEnv      ( FamInstEnv, topNormaliseType_maybe )
import GHC.Core.DataCon
   ( DataCon, dataConWorkId, dataConRepStrictness
   , dataConRepArgTys, isUnboxedTupleDataCon
   , StrictnessMark (..), dataConWrapId_maybe )
import GHC.Core.Opt.Stats ( Tick(..) )
import GHC.Core.Ppr     ( pprCoreExpr )
import GHC.Core.Unfold
import GHC.Core.Unfold.Make
import GHC.Core.Utils
import GHC.Core.Opt.Arity ( ArityType, exprArity, arityTypeBotSigs_maybe
                          , pushCoTyArg, pushCoValArg, exprIsDeadEnd
                          , typeArity, arityTypeArity, etaExpandAT )
import GHC.Core.SimpleOpt ( exprIsConApp_maybe, joinPointBinding_maybe, joinPointBindings_maybe )
import GHC.Core.FVs     ( mkRuleInfo {- exprsFreeIds -} )
import GHC.Core.Rules   ( lookupRule, getRules )
import GHC.Core.Multiplicity

import GHC.Types.Literal   ( litIsLifted ) --, mkLitInt ) -- temporarily commented out. See #8326
import GHC.Types.SourceText
import GHC.Types.Id
import GHC.Types.Id.Make   ( seqId )
import GHC.Types.Id.Info
import GHC.Types.Name   ( mkSystemVarName, isExternalName, getOccFS )
import GHC.Types.Demand
import GHC.Types.Unique ( hasKey )
import GHC.Types.Basic
import GHC.Types.Tickish
import GHC.Types.Var    ( isTyCoVar )
import GHC.Builtin.Types.Prim( realWorldStatePrimTy )
import GHC.Builtin.Names( runRWKey, seqHashKey )

import GHC.Data.Maybe   ( isNothing, orElse, mapMaybe )
import GHC.Data.FastString
import GHC.Unit.Module ( moduleName )
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Constants (debugIsOn)
import GHC.Utils.Monad  ( mapAccumLM, liftIO )
import GHC.Utils.Logger
import GHC.Utils.Misc

import Control.Monad

{-
The guts of the simplifier is in this module, but the driver loop for
the simplifier is in GHC.Core.Opt.Pipeline

Note [The big picture]
~~~~~~~~~~~~~~~~~~~~~~
The general shape of the simplifier is this:

  simplExpr :: SimplEnv -> InExpr -> SimplCont -> SimplM (SimplFloats, OutExpr)
  simplBind :: SimplEnv -> InBind -> SimplM (SimplFloats, SimplEnv)

 * SimplEnv contains
     - Simplifier mode
     - Ambient substitution
     - InScopeSet

 * SimplFloats contains
     - Let-floats (which includes ok-for-spec case-floats)
     - Join floats
     - InScopeSet (including all the floats)

 * Expressions
      simplExpr :: SimplEnv -> InExpr -> SimplCont
                -> SimplM (SimplFloats, OutExpr)
   The result of simplifying an /expression/ is (floats, expr)
      - A bunch of floats (let bindings, join bindings)
      - A simplified expression.
   The overall result is effectively (let floats in expr)

 * Bindings
      simplBind :: SimplEnv -> InBind -> SimplM (SimplFloats, SimplEnv)
   The result of simplifying a binding is
     - A bunch of floats, the last of which is the simplified binding
       There may be auxiliary bindings too; see prepareRhs
     - An environment suitable for simplifying the scope of the binding

   The floats may also be empty, if the binding is inlined unconditionally;
   in that case the returned SimplEnv will have an augmented substitution.

   The returned floats and env both have an in-scope set, and they are
   guaranteed to be the same.

Eta expansion
~~~~~~~~~~~~~~
For eta expansion, we want to catch things like

        case e of (a,b) -> \x -> case a of (p,q) -> \y -> r

If the \x was on the RHS of a let, we'd eta expand to bring the two
lambdas together.  And in general that's a good thing to do.  Perhaps
we should eta expand wherever we find a (value) lambda?  Then the eta
expansion at a let RHS can concentrate solely on the PAP case.

Note [In-scope set as a substitution]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As per Note [Lookups in in-scope set], an in-scope set can act as
a substitution. Specifically, it acts as a substitution from variable to
variables /with the same unique/.

Why do we need this? Well, during the course of the simplifier, we may want to
adjust inessential properties of a variable. For instance, when performing a
beta-reduction, we change

    (\x. e) u ==> let x = u in e

We typically want to add an unfolding to `x` so that it inlines to (the
simplification of) `u`.

We do that by adding the unfolding to the binder `x`, which is added to the
in-scope set. When simplifying occurrences of `x` (every occurrence!), they are
replaced by their “updated” version from the in-scope set, hence inherit the
unfolding. This happens in `SimplEnv.substId`.

Another example. Consider

   case x of y { Node a b -> ...y...
               ; Leaf v   -> ...y... }

In the Node branch want y's unfolding to be (Node a b); in the Leaf branch we
want y's unfolding to be (Leaf v). We achieve this by adding the appropriate
unfolding to y, and re-adding it to the in-scope set. See the calls to
`addBinderUnfolding` in `Simplify.addAltUnfoldings` and elsewhere.

It's quite convenient. This way we don't need to manipulate the substitution all
the time: every update to a binder is automatically reflected to its bound
occurrences.

Note [Bangs in the Simplifier]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Both SimplFloats and SimplEnv do *not* generally benefit from making
their fields strict. I don't know if this is because of good use of
laziness or unintended side effects like closures capturing more variables
after WW has run.

But the end result is that we keep these lazy, but force them in some places
where we know it's beneficial to the compiler.

Similarly environments returned from functions aren't *always* beneficial to
force. In some places they would never be demanded so forcing them early
increases allocation. In other places they almost always get demanded so
it's worthwhile to force them early.

Would it be better to through every allocation of e.g. SimplEnv and decide
wether or not to make this one strict? Absolutely! Would be a good use of
someones time? Absolutely not! I made these strict that showed up during
a profiled build or which I noticed while looking at core for one reason
or another.

The result sadly is that we end up with "random" bangs in the simplifier
where we sometimes force e.g. the returned environment from a function and
sometimes we don't for the same function. Depending on the context around
the call. The treatment is also not very consistent. I only added bangs
where I saw it making a difference either in the core or benchmarks. Some
patterns where it would be beneficial aren't convered as a consequence as
I neither have the time to go through all of the core and some cases are
too small to show up in benchmarks.



************************************************************************
*                                                                      *
\subsection{Bindings}
*                                                                      *
************************************************************************
-}

simplTopBinds :: SimplEnv -> [InBind] -> SimplM (SimplFloats, SimplEnv)
-- See Note [The big picture]
simplTopBinds :: SimplEnv -> [InBind] -> SimplM (SimplFloats, SimplEnv)
simplTopBinds SimplEnv
env0 [InBind]
binds0
  = do  {       -- Put all the top-level binders into scope at the start
                -- so that if a rewrite rule has unexpectedly brought
                -- anything into scope, then we don't get a complaint about that.
                -- It's rather as if the top-level binders were imported.
                -- See Note [Glomming] in "GHC.Core.Opt.OccurAnal".
        -- See Note [Bangs in the Simplifier]
        ; !env1 <- {-#SCC "simplTopBinds-simplRecBndrs" #-} SimplEnv -> [CoreBndr] -> SimplM SimplEnv
simplRecBndrs SimplEnv
env0 ([InBind] -> [CoreBndr]
forall b. [Bind b] -> [b]
bindersOfBinds [InBind]
binds0)
        ; (floats, env2) <- {-#SCC "simplTopBinds-simpl_binds" #-} simpl_binds env1 binds0
        ; freeTick SimplifierDone
        ; return (floats, env2) }
  where
        -- We need to track the zapped top-level binders, because
        -- they should have their fragile IdInfo zapped (notably occurrence info)
        -- That's why we run down binds and bndrs' simultaneously.
        --
    simpl_binds :: SimplEnv -> [InBind] -> SimplM (SimplFloats, SimplEnv)
    simpl_binds :: SimplEnv -> [InBind] -> SimplM (SimplFloats, SimplEnv)
simpl_binds SimplEnv
env []           = (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, SimplEnv
env)
    simpl_binds SimplEnv
env (InBind
bind:[InBind]
binds) = do { (float,  env1) <- SimplEnv -> InBind -> SimplM (SimplFloats, SimplEnv)
simpl_bind SimplEnv
env InBind
bind
                                      ; (floats, env2) <- simpl_binds env1 binds
                                      -- See Note [Bangs in the Simplifier]
                                      ; let !floats1 = SimplFloats
float SimplFloats -> SimplFloats -> SimplFloats
`addFloats` SimplFloats
floats
                                      ; return (floats1, env2) }

    simpl_bind :: SimplEnv -> InBind -> SimplM (SimplFloats, SimplEnv)
simpl_bind SimplEnv
env (Rec [(CoreBndr, CoreExpr)]
pairs)
      = SimplEnv
-> BindContext
-> [(CoreBndr, CoreExpr)]
-> SimplM (SimplFloats, SimplEnv)
simplRecBind SimplEnv
env (TopLevelFlag -> RecFlag -> BindContext
BC_Let TopLevelFlag
TopLevel RecFlag
Recursive) [(CoreBndr, CoreExpr)]
pairs
    simpl_bind SimplEnv
env (NonRec CoreBndr
b CoreExpr
r)
      = do { let bind_cxt :: BindContext
bind_cxt = TopLevelFlag -> RecFlag -> BindContext
BC_Let TopLevelFlag
TopLevel RecFlag
NonRecursive
           ; (env', b') <- SimplEnv
-> CoreBndr
-> CoreBndr
-> BindContext
-> SimplM (SimplEnv, CoreBndr)
addBndrRules SimplEnv
env CoreBndr
b (SimplEnv -> CoreBndr -> CoreBndr
lookupRecBndr SimplEnv
env CoreBndr
b) BindContext
bind_cxt
           ; simplRecOrTopPair env' bind_cxt b b' r }

{-
************************************************************************
*                                                                      *
        Lazy bindings
*                                                                      *
************************************************************************

simplRecBind is used for
        * recursive bindings only
-}

simplRecBind :: SimplEnv -> BindContext
             -> [(InId, InExpr)]
             -> SimplM (SimplFloats, SimplEnv)
simplRecBind :: SimplEnv
-> BindContext
-> [(CoreBndr, CoreExpr)]
-> SimplM (SimplFloats, SimplEnv)
simplRecBind SimplEnv
env0 BindContext
bind_cxt [(CoreBndr, CoreExpr)]
pairs0
  = do  { (env1, triples) <- (SimplEnv
 -> (CoreBndr, CoreExpr)
 -> SimplM (SimplEnv, (CoreBndr, CoreBndr, CoreExpr)))
-> SimplEnv
-> [(CoreBndr, CoreExpr)]
-> SimplM (SimplEnv, [(CoreBndr, CoreBndr, CoreExpr)])
forall (m :: * -> *) (t :: * -> *) acc x y.
(Monad m, Traversable t) =>
(acc -> x -> m (acc, y)) -> acc -> t x -> m (acc, t y)
mapAccumLM SimplEnv
-> (CoreBndr, CoreExpr)
-> SimplM (SimplEnv, (CoreBndr, CoreBndr, CoreExpr))
add_rules SimplEnv
env0 [(CoreBndr, CoreExpr)]
pairs0
        ; let new_bndrs = ((CoreBndr, CoreBndr, CoreExpr) -> CoreBndr)
-> [(CoreBndr, CoreBndr, CoreExpr)] -> [CoreBndr]
forall a b. (a -> b) -> [a] -> [b]
map (CoreBndr, CoreBndr, CoreExpr) -> CoreBndr
forall a b c. (a, b, c) -> b
sndOf3 [(CoreBndr, CoreBndr, CoreExpr)]
triples
        ; (rec_floats, env2) <- enterRecGroupRHSs env1 new_bndrs $ \SimplEnv
env ->
                                SimplEnv
-> [(CoreBndr, CoreBndr, CoreExpr)]
-> SimplM (SimplFloats, SimplEnv)
go SimplEnv
env [(CoreBndr, CoreBndr, CoreExpr)]
triples
        ; return (mkRecFloats rec_floats, env2) }
  where
    add_rules :: SimplEnv -> (InBndr,InExpr) -> SimplM (SimplEnv, (InBndr, OutBndr, InExpr))
        -- Add the (substituted) rules to the binder
    add_rules :: SimplEnv
-> (CoreBndr, CoreExpr)
-> SimplM (SimplEnv, (CoreBndr, CoreBndr, CoreExpr))
add_rules SimplEnv
env (CoreBndr
bndr, CoreExpr
rhs)
        = do { (env', bndr') <- SimplEnv
-> CoreBndr
-> CoreBndr
-> BindContext
-> SimplM (SimplEnv, CoreBndr)
addBndrRules SimplEnv
env CoreBndr
bndr (SimplEnv -> CoreBndr -> CoreBndr
lookupRecBndr SimplEnv
env CoreBndr
bndr) BindContext
bind_cxt
             ; return (env', (bndr, bndr', rhs)) }

    go :: SimplEnv
-> [(CoreBndr, CoreBndr, CoreExpr)]
-> SimplM (SimplFloats, SimplEnv)
go SimplEnv
env [] = (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, SimplEnv
env)

    go SimplEnv
env ((CoreBndr
old_bndr, CoreBndr
new_bndr, CoreExpr
rhs) : [(CoreBndr, CoreBndr, CoreExpr)]
pairs)
        = do { (float, env1) <- SimplEnv
-> BindContext
-> CoreBndr
-> CoreBndr
-> CoreExpr
-> SimplM (SimplFloats, SimplEnv)
simplRecOrTopPair SimplEnv
env BindContext
bind_cxt
                                                  CoreBndr
old_bndr CoreBndr
new_bndr CoreExpr
rhs
             ; (floats, env2) <- go env1 pairs
             ; return (float `addFloats` floats, env2) }

{-
simplOrTopPair is used for
        * recursive bindings (whether top level or not)
        * top-level non-recursive bindings

It assumes the binder has already been simplified, but not its IdInfo.
-}

simplRecOrTopPair :: SimplEnv
                  -> BindContext
                  -> InId -> OutBndr -> InExpr  -- Binder and rhs
                  -> SimplM (SimplFloats, SimplEnv)

simplRecOrTopPair :: SimplEnv
-> BindContext
-> CoreBndr
-> CoreBndr
-> CoreExpr
-> SimplM (SimplFloats, SimplEnv)
simplRecOrTopPair SimplEnv
env BindContext
bind_cxt CoreBndr
old_bndr CoreBndr
new_bndr CoreExpr
rhs
  | Just SimplEnv
env' <- SimplEnv
-> TopLevelFlag
-> CoreBndr
-> CoreExpr
-> SimplEnv
-> Maybe SimplEnv
preInlineUnconditionally SimplEnv
env (BindContext -> TopLevelFlag
bindContextLevel BindContext
bind_cxt)
                                          CoreBndr
old_bndr CoreExpr
rhs SimplEnv
env
  = {-#SCC "simplRecOrTopPair-pre-inline-uncond" #-}
    String
-> SDoc
-> SimplM (SimplFloats, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
forall a. String -> SDoc -> SimplM a -> SimplM a
simplTrace String
"SimplBindr:inline-uncond" (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
old_bndr) (SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv))
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a b. (a -> b) -> a -> b
$
    do { Tick -> SimplM ()
tick (CoreBndr -> Tick
PreInlineUnconditionally CoreBndr
old_bndr)
       ; (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return ( SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, SimplEnv
env' ) }

  | Bool
otherwise
  = case BindContext
bind_cxt of
      BC_Join RecFlag
is_rec SimplCont
cont -> String
-> SDoc
-> SimplM (SimplFloats, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
forall a. String -> SDoc -> SimplM a -> SimplM a
simplTrace String
"SimplBind:join" (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
old_bndr) (SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv))
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a b. (a -> b) -> a -> b
$
                             RecFlag
-> SimplCont
-> (CoreBndr, SimplEnv)
-> (CoreBndr, SimplEnv)
-> (CoreExpr, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
simplJoinBind RecFlag
is_rec SimplCont
cont
                                           (CoreBndr
old_bndr,SimplEnv
env) (CoreBndr
new_bndr,SimplEnv
env) (CoreExpr
rhs,SimplEnv
env)

      BC_Let TopLevelFlag
top_lvl RecFlag
is_rec -> String
-> SDoc
-> SimplM (SimplFloats, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
forall a. String -> SDoc -> SimplM a -> SimplM a
simplTrace String
"SimplBind:normal" (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
old_bndr) (SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv))
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a b. (a -> b) -> a -> b
$
                               TopLevelFlag
-> RecFlag
-> (CoreBndr, SimplEnv)
-> (CoreBndr, SimplEnv)
-> (CoreExpr, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
simplLazyBind TopLevelFlag
top_lvl RecFlag
is_rec
                                             (CoreBndr
old_bndr,SimplEnv
env) (CoreBndr
new_bndr,SimplEnv
env) (CoreExpr
rhs,SimplEnv
env)

simplTrace :: String -> SDoc -> SimplM a -> SimplM a
simplTrace :: forall a. String -> SDoc -> SimplM a -> SimplM a
simplTrace String
herald SDoc
doc SimplM a
thing_inside = do
  logger <- SimplM Logger
forall (m :: * -> *). HasLogger m => m Logger
getLogger
  if logHasDumpFlag logger Opt_D_verbose_core2core
    then logTraceMsg logger herald doc thing_inside
    else thing_inside

--------------------------
simplLazyBind :: TopLevelFlag -> RecFlag
              -> (InId, SimplEnv)       -- InBinder, and static env for its unfolding (if any)
              -> (OutId, SimplEnv)      -- OutBinder, and SimplEnv after simplifying that binder
                                        -- The OutId has IdInfo (notably RULES),
                                        -- except arity, unfolding
              -> (InExpr, SimplEnv)     -- The RHS and its static environment
              -> SimplM (SimplFloats, SimplEnv)
-- Precondition: Ids only, no TyVars; not a JoinId
-- Precondition: rhs obeys the let-can-float invariant
simplLazyBind :: TopLevelFlag
-> RecFlag
-> (CoreBndr, SimplEnv)
-> (CoreBndr, SimplEnv)
-> (CoreExpr, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
simplLazyBind TopLevelFlag
top_lvl RecFlag
is_rec (CoreBndr
bndr,SimplEnv
unf_se) (CoreBndr
bndr1,SimplEnv
env) (CoreExpr
rhs,SimplEnv
rhs_se)
  = Bool
-> (Bool
    -> SDoc
    -> SimplM (SimplFloats, SimplEnv)
    -> SimplM (SimplFloats, SimplEnv))
-> Bool
-> SDoc
-> SimplM (SimplFloats, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
forall a. HasCallStack => Bool -> a -> a
assert (CoreBndr -> Bool
isId CoreBndr
bndr )
    Bool
-> SDoc
-> SimplM (SimplFloats, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (Bool -> Bool
not (CoreBndr -> Bool
isJoinId CoreBndr
bndr)) (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr) (SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv))
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a b. (a -> b) -> a -> b
$
    -- pprTrace "simplLazyBind" ((ppr bndr <+> ppr bndr1) $$ ppr rhs $$ ppr (seIdSubst rhs_se)) $
    do  { let   !rhs_env :: SimplEnv
rhs_env     = SimplEnv
rhs_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env -- See Note [Bangs in the Simplifier]
                ([CoreBndr]
tvs, CoreExpr
body) = case CoreExpr -> ([CoreBndr], [CoreBndr], CoreExpr)
collectTyAndValBinders CoreExpr
rhs of
                                ([CoreBndr]
tvs, [], CoreExpr
body)
                                  | CoreExpr -> Bool
forall {b}. Expr b -> Bool
surely_not_lam CoreExpr
body -> ([CoreBndr]
tvs, CoreExpr
body)
                                ([CoreBndr], [CoreBndr], CoreExpr)
_                       -> ([], CoreExpr
rhs)

                surely_not_lam :: Expr b -> Bool
surely_not_lam (Lam {})     = Bool
False
                surely_not_lam (Tick CoreTickish
t Expr b
e)
                  | Bool -> Bool
not (CoreTickish -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishFloatable CoreTickish
t) = Expr b -> Bool
surely_not_lam Expr b
e
                   -- eta-reduction could float
                surely_not_lam Expr b
_            = Bool
True
                        -- Do not do the "abstract tyvar" thing if there's
                        -- a lambda inside, because it defeats eta-reduction
                        --    f = /\a. \x. g a x
                        -- should eta-reduce.

        ; (body_env, tvs') <- {-#SCC "simplBinders" #-} SimplEnv -> [CoreBndr] -> SimplM (SimplEnv, [CoreBndr])
simplBinders SimplEnv
rhs_env [CoreBndr]
tvs
                -- See Note [Floating and type abstraction] in GHC.Core.Opt.Simplify.Utils

        -- Simplify the RHS
        ; let rhs_cont = Kind -> RecFlag -> Demand -> SimplCont
mkRhsStop (HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
body_env (HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
body))
                                   RecFlag
is_rec (CoreBndr -> Demand
idDemandInfo CoreBndr
bndr)
        ; (body_floats0, body0) <- {-#SCC "simplExprF" #-} simplExprF body_env body rhs_cont

        -- ANF-ise a constructor or PAP rhs
        ; (body_floats2, body2) <- {-#SCC "prepareBinding" #-}
                                   prepareBinding env top_lvl is_rec
                                                  False  -- Not strict; this is simplLazyBind
                                                  bndr1 body_floats0 body0
          -- Subtle point: we do not need or want tvs' in the InScope set
          -- of body_floats2, so we pass in 'env' not 'body_env'.
          -- Don't want: if tvs' are in-scope in the scope of this let-binding, we may do
          -- more renaming than necessary => extra work (see !7777 and test T16577).
          -- Don't need: we wrap tvs' around the RHS anyway.

        ; (rhs_floats, body3)
            <-  if isEmptyFloats body_floats2 || null tvs then   -- Simple floating
                     {-#SCC "simplLazyBind-simple-floating" #-}
                     return (body_floats2, body2)

                else -- Non-empty floats, and non-empty tyvars: do type-abstraction first
                     {-#SCC "simplLazyBind-type-abstraction-first" #-}
                     do { (poly_binds, body3) <- abstractFloats (seUnfoldingOpts env) top_lvl
                                                                tvs' body_floats2 body2
                        ; let poly_floats = (SimplFloats -> InBind -> SimplFloats)
-> SimplFloats -> [InBind] -> SimplFloats
forall b a. (b -> a -> b) -> b -> [a] -> b
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' SimplFloats -> InBind -> SimplFloats
extendFloats (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env) [InBind]
poly_binds
                        ; return (poly_floats, body3) }

        ; let env1 = SimplEnv
env SimplEnv -> SimplFloats -> SimplEnv
`setInScopeFromF` SimplFloats
rhs_floats
        ; rhs' <- rebuildLam env1 tvs' body3 rhs_cont
        ; (bind_float, env2) <- completeBind (BC_Let top_lvl is_rec) (bndr,unf_se) (bndr1,rhs',env1)
        ; return (rhs_floats `addFloats` bind_float, env2) }

--------------------------
simplJoinBind :: RecFlag
              -> SimplCont
              -> (InId, SimplEnv)       -- InBinder, with static env for its unfolding
              -> (OutId, SimplEnv)      -- OutBinder; SimplEnv has the binder in scope
                                        -- The OutId has IdInfo, except arity, unfolding
              -> (InExpr, SimplEnv)     -- The right hand side and its env
              -> SimplM (SimplFloats, SimplEnv)
simplJoinBind :: RecFlag
-> SimplCont
-> (CoreBndr, SimplEnv)
-> (CoreBndr, SimplEnv)
-> (CoreExpr, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
simplJoinBind RecFlag
is_rec SimplCont
cont (CoreBndr
old_bndr, SimplEnv
unf_se) (CoreBndr
new_bndr, SimplEnv
env) (CoreExpr
rhs, SimplEnv
rhs_se)
  = do  { let rhs_env :: SimplEnv
rhs_env = SimplEnv
rhs_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env
        ; rhs' <- SimplEnv -> CoreBndr -> CoreExpr -> SimplCont -> SimplM CoreExpr
simplJoinRhs SimplEnv
rhs_env CoreBndr
old_bndr CoreExpr
rhs SimplCont
cont
        ; completeBind (BC_Join is_rec cont) (old_bndr, unf_se) (new_bndr, rhs', env) }

--------------------------
simplAuxBind :: String
             -> SimplEnv
             -> InId            -- Old binder; not a JoinId
             -> OutExpr         -- Simplified RHS
             -> SimplM (SimplFloats, SimplEnv)
-- A specialised variant of completeBindX used to construct non-recursive
-- auxiliary bindings, notably in knownCon.
--
-- The binder comes from a case expression (case binder or alternative)
-- and so does not have rules, unfolding, inline pragmas etc.
--
-- Precondition: rhs satisfies the let-can-float invariant

simplAuxBind :: String
-> SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplM (SimplFloats, SimplEnv)
simplAuxBind String
_str SimplEnv
env CoreBndr
bndr CoreExpr
new_rhs
  | Bool -> SDoc -> Bool -> Bool
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (CoreBndr -> Bool
isId CoreBndr
bndr Bool -> Bool -> Bool
&& Bool -> Bool
not (CoreBndr -> Bool
isJoinId CoreBndr
bndr)) (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr) (Bool -> Bool) -> Bool -> Bool
forall a b. (a -> b) -> a -> b
$
    CoreBndr -> Bool
isDeadBinder CoreBndr
bndr   -- Not uncommon; e.g. case (a,b) of c { (p,q) -> p }
  = (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, SimplEnv
env)    --  Here c is dead, and we avoid
                                     --  creating the binding c = (a,b)

  -- Next we have a fast-path for cases that would be inlined unconditionally by
  -- completeBind: but it seems not uncommon, and it turns to be a little more
  -- efficient (in compile time allocations) to do it here.
  -- Effectively this is just a vastly-simplified postInlineUnconditionally
  --   See Note [Post-inline for single-use things] in GHC.Core.Opt.Simplify.Utils
  -- We could instead use postInlineUnconditionally itself, but I think it's simpler
  --   and more direct to focus on the "hot" cases.
  -- e.g. auxiliary bindings have no NOLINE pragmas, RULEs, or stable unfoldings
  | CoreExpr -> Bool
exprIsTrivial CoreExpr
new_rhs  -- Short-cut for let x = y in ...
    Bool -> Bool -> Bool
|| case (CoreBndr -> OccInfo
idOccInfo CoreBndr
bndr) of
          OneOcc{ occ_n_br :: OccInfo -> Int
occ_n_br = Int
1, occ_in_lam :: OccInfo -> InsideLam
occ_in_lam = InsideLam
NotInsideLam } -> Bool
True
          OccInfo
_                                                 -> Bool
False
  = (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return ( SimplEnv -> SimplFloats
emptyFloats SimplEnv
env
           , SimplEnv -> CoreBndr -> CoreExpr -> SimplEnv
extendCvIdSubst SimplEnv
env CoreBndr
bndr CoreExpr
new_rhs )  -- bndr can be a CoVar

  | Bool
otherwise
  = do  { -- ANF-ise the RHS
          let !occ_fs :: FastString
occ_fs = CoreBndr -> FastString
forall a. NamedThing a => a -> FastString
getOccFS CoreBndr
bndr
        ; (anf_floats, rhs1) <- HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
prepareRhs SimplEnv
env TopLevelFlag
NotTopLevel FastString
occ_fs CoreExpr
new_rhs
        ; unless (isEmptyLetFloats anf_floats) (tick LetFloatFromLet)
        ; let rhs_floats = SimplEnv -> SimplFloats
emptyFloats SimplEnv
env SimplFloats -> LetFloats -> SimplFloats
`addLetFloats` LetFloats
anf_floats

          -- Simplify the binder and complete the binding
        ; (env1, new_bndr) <- simplBinder (env `setInScopeFromF` rhs_floats) bndr
        ; (bind_float, env2) <- completeBind (BC_Let NotTopLevel NonRecursive)
                                             (bndr,env) (new_bndr, rhs1, env1)

        ; return (rhs_floats `addFloats` bind_float, env2) }


{- *********************************************************************
*                                                                      *
           Cast worker/wrapper
*                                                                      *
************************************************************************

Note [Cast worker/wrapper]
~~~~~~~~~~~~~~~~~~~~~~~~~~
When we have a binding
   x = e |> co
we want to do something very similar to worker/wrapper:
   $wx = e
   x = $wx |> co

We call this making a cast worker/wrapper in tryCastWorkerWrapper.

The main motivaiton is that x can be inlined freely.  There's a chance
that e will be a constructor application or function, or something
like that, so moving the coercion to the usage site may well cancel
the coercions and lead to further optimisation.  Example:

     data family T a :: *
     data instance T Int = T Int

     foo :: Int -> Int -> Int
     foo m n = ...
        where
          t = T m
          go 0 = 0
          go n = case t of { T m -> go (n-m) }
                -- This case should optimise

A second reason for doing cast worker/wrapper is that the worker/wrapper
pass after strictness analysis can't deal with RHSs like
     f = (\ a b c. blah) |> co
Instead, it relies on cast worker/wrapper to get rid of the cast,
leaving a simpler job for demand-analysis worker/wrapper.  See #19874.

Wrinkles

1. We must /not/ do cast w/w on
     f = g |> co
   otherwise it'll just keep repeating forever! You might think this
   is avoided because the call to tryCastWorkerWrapper is guarded by
   preInlineUnconditinally, but I'm worried that a loop-breaker or an
   exported Id might say False to preInlineUnonditionally.

2. We need to be careful with inline/noinline pragmas:
       rec { {-# NOINLINE f #-}
             f = (...g...) |> co
           ; g = ...f... }
   This is legitimate -- it tells GHC to use f as the loop breaker
   rather than g.  Now we do the cast thing, to get something like
       rec { $wf = ...g...
           ; f = $wf |> co
           ; g = ...f... }
   Where should the NOINLINE pragma go?  If we leave it on f we'll get
     rec { $wf = ...g...
         ; {-# NOINLINE f #-}
           f = $wf |> co
         ; g = ...f... }
   and that is bad: the whole point is that we want to inline that
   cast!  We want to transfer the pagma to $wf:
      rec { {-# NOINLINE $wf #-}
            $wf = ...g...
          ; f = $wf |> co
          ; g = ...f... }
   c.f. Note [Worker/wrapper for NOINLINE functions] in GHC.Core.Opt.WorkWrap.

3. We should still do cast w/w even if `f` is INLINEABLE.  E.g.
      {- f: Stable unfolding = <stable-big> -}
      f = (\xy. <big-body>) |> co
   Then we want to w/w to
      {- $wf: Stable unfolding = <stable-big> |> sym co -}
      $wf = \xy. <big-body>
      f = $wf |> co
   Notice that the stable unfolding moves to the worker!  Now demand analysis
   will work fine on $wf, whereas it has trouble with the original f.
   c.f. Note [Worker/wrapper for INLINABLE functions] in GHC.Core.Opt.WorkWrap.
   This point also applies to strong loopbreakers with INLINE pragmas, see
   wrinkle (4).

4. We should /not/ do cast w/w for non-loop-breaker INLINE functions (hence
   hasInlineUnfolding in tryCastWorkerWrapper, which responds False to
   loop-breakers) because they'll definitely be inlined anyway, cast and
   all. And if we do cast w/w for an INLINE function with arity zero, we get
   something really silly: we inline that "worker" right back into the wrapper!
   Worse than a no-op, because we have then lost the stable unfolding.

All these wrinkles are exactly like worker/wrapper for strictness analysis:
  f is the wrapper and must inline like crazy
  $wf is the worker and must carry f's original pragma
See Note [Worker/wrapper for INLINABLE functions]
and Note [Worker/wrapper for NOINLINE functions] in GHC.Core.Opt.WorkWrap.

See #17673, #18093, #18078, #19890.

Note [Preserve strictness in cast w/w]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the Note [Cast worker/wrapper] transformation, keep the strictness info.
Eg
        f = e `cast` co    -- f has strictness SSL
When we transform to
        f' = e             -- f' also has strictness SSL
        f = f' `cast` co   -- f still has strictness SSL

Its not wrong to drop it on the floor, but better to keep it.

Note [Preserve RuntimeRep info in cast w/w]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We must not do cast w/w when the presence of the coercion is needed in order
to determine the runtime representation.

Example:

  Suppose we have a type family:

    type F :: RuntimeRep
    type family F where
      F = LiftedRep

  together with a type `ty :: TYPE F` and a top-level binding

    a :: ty |> TYPE F[0]

  The kind of `ty |> TYPE F[0]` is `LiftedRep`, so `a` is a top-level lazy binding.
  However, were we to apply cast w/w, we would get:

    b :: ty
    b = ...

    a :: ty |> TYPE F[0]
    a = b `cast` GRefl (TYPE F[0])

  Now we are in trouble because `ty :: TYPE F` does not have a known runtime
  representation, because we need to be able to reduce the nullary type family
  application `F` to find that out.

Conclusion: only do cast w/w when doing so would not lose the RuntimeRep
information. That is, when handling `Cast rhs co`, don't attempt cast w/w
unless the kind of the type of rhs is concrete, in the sense of
Note [Concrete types] in GHC.Tc.Utils.Concrete.
-}

tryCastWorkerWrapper :: SimplEnv -> BindContext
                     -> InId -> OutId -> OutExpr
                     -> SimplM (SimplFloats, SimplEnv)
-- See Note [Cast worker/wrapper]
tryCastWorkerWrapper :: SimplEnv
-> BindContext
-> CoreBndr
-> CoreBndr
-> CoreExpr
-> SimplM (SimplFloats, SimplEnv)
tryCastWorkerWrapper SimplEnv
env BindContext
bind_cxt CoreBndr
old_bndr CoreBndr
bndr (Cast CoreExpr
rhs CoercionR
co)
  | BC_Let TopLevelFlag
top_lvl RecFlag
is_rec <- BindContext
bind_cxt  -- Not join points
  , Bool -> Bool
not (CoreBndr -> Bool
isDFunId CoreBndr
bndr) -- nor DFuns; cast w/w is no help, and we can't transform
                        --            a DFunUnfolding in mk_worker_unfolding
  , Bool -> Bool
not (CoreExpr -> Bool
exprIsTrivial CoreExpr
rhs)        -- Not x = y |> co; Wrinkle 1
  , Bool -> Bool
not (IdInfo -> Bool
hasInlineUnfolding IdInfo
info)  -- Not INLINE things: Wrinkle 4
  , HasDebugCallStack => Kind -> Bool
Kind -> Bool
typeHasFixedRuntimeRep Kind
work_ty    -- Don't peel off a cast if doing so would
                                      -- lose the underlying runtime representation.
                                      -- See Note [Preserve RuntimeRep info in cast w/w]
  , Bool -> Bool
not (InlinePragma -> Bool
isOpaquePragma (CoreBndr -> InlinePragma
idInlinePragma CoreBndr
old_bndr)) -- Not for OPAQUE bindings
                                                   -- See Note [OPAQUE pragma]
  = do  { uniq <- SimplM Unique
forall (m :: * -> *). MonadUnique m => m Unique
getUniqueM
        ; let work_name = Unique -> FastString -> Name
mkSystemVarName Unique
uniq FastString
occ_fs
              work_id   = HasDebugCallStack => Name -> Kind -> Kind -> IdInfo -> CoreBndr
Name -> Kind -> Kind -> IdInfo -> CoreBndr
mkLocalIdWithInfo Name
work_name Kind
ManyTy Kind
work_ty IdInfo
work_info
              is_strict = CoreBndr -> Bool
isStrictId CoreBndr
bndr

        ; (rhs_floats, work_rhs) <- prepareBinding env top_lvl is_rec is_strict
                                                   work_id (emptyFloats env) rhs

        ; work_unf <- mk_worker_unfolding top_lvl work_id work_rhs
        ; let  work_id_w_unf = CoreBndr
work_id CoreBndr -> Unfolding -> CoreBndr
`setIdUnfolding` Unfolding
work_unf
               floats   = SimplFloats
rhs_floats SimplFloats -> LetFloats -> SimplFloats
`addLetFloats`
                          InBind -> LetFloats
unitLetFloat (CoreBndr -> CoreExpr -> InBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
work_id_w_unf CoreExpr
work_rhs)

               triv_rhs = CoreExpr -> CoercionR -> CoreExpr
forall b. Expr b -> CoercionR -> Expr b
Cast (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
work_id_w_unf) CoercionR
co

        ; if postInlineUnconditionally env bind_cxt old_bndr bndr triv_rhs
             -- Almost always True, because the RHS is trivial
             -- In that case we want to eliminate the binding fast
             -- We conservatively use postInlineUnconditionally so that we
             -- check all the right things
          then do { tick (PostInlineUnconditionally bndr)
                  ; return ( floats
                           , extendIdSubst (setInScopeFromF env floats) old_bndr $
                             DoneEx triv_rhs NotJoinPoint ) }

          else do { wrap_unf <- mkLetUnfolding env top_lvl VanillaSrc bndr False triv_rhs
                  ; let bndr' = CoreBndr
bndr CoreBndr -> InlinePragma -> CoreBndr
`setInlinePragma` InlinePragma -> InlinePragma
mkCastWrapperInlinePrag (CoreBndr -> InlinePragma
idInlinePragma CoreBndr
bndr)
                                CoreBndr -> Unfolding -> CoreBndr
`setIdUnfolding`  Unfolding
wrap_unf
                        floats' = SimplFloats
floats SimplFloats -> InBind -> SimplFloats
`extendFloats` CoreBndr -> CoreExpr -> InBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
bndr' CoreExpr
triv_rhs
                  ; return ( floats', setInScopeFromF env floats' ) } }
  where
    -- Force the occ_fs so that the old Id is not retained in the new Id.
    !occ_fs :: FastString
occ_fs = CoreBndr -> FastString
forall a. NamedThing a => a -> FastString
getOccFS CoreBndr
bndr
    work_ty :: Kind
work_ty = CoercionR -> Kind
coercionLKind CoercionR
co
    info :: IdInfo
info   = HasDebugCallStack => CoreBndr -> IdInfo
CoreBndr -> IdInfo
idInfo CoreBndr
bndr
    work_arity :: Int
work_arity = IdInfo -> Int
arityInfo IdInfo
info Int -> Int -> Int
forall a. Ord a => a -> a -> a
`min` Kind -> Int
typeArity Kind
work_ty

    work_info :: IdInfo
work_info = IdInfo
vanillaIdInfo IdInfo -> DmdSig -> IdInfo
`setDmdSigInfo`     IdInfo -> DmdSig
dmdSigInfo IdInfo
info
                              IdInfo -> CprSig -> IdInfo
`setCprSigInfo`     IdInfo -> CprSig
cprSigInfo IdInfo
info
                              IdInfo -> Demand -> IdInfo
`setDemandInfo`     IdInfo -> Demand
demandInfo IdInfo
info
                              IdInfo -> InlinePragma -> IdInfo
`setInlinePragInfo` IdInfo -> InlinePragma
inlinePragInfo IdInfo
info
                              IdInfo -> Int -> IdInfo
`setArityInfo`      Int
work_arity
           -- We do /not/ want to transfer OccInfo, Rules
           -- Note [Preserve strictness in cast w/w]
           -- and Wrinkle 2 of Note [Cast worker/wrapper]

    ----------- Worker unfolding -----------
    -- Stable case: if there is a stable unfolding we have to compose with (Sym co);
    --   the next round of simplification will do the job
    -- Non-stable case: use work_rhs
    -- Wrinkle 3 of Note [Cast worker/wrapper]
    mk_worker_unfolding :: TopLevelFlag -> CoreBndr -> CoreExpr -> SimplM Unfolding
mk_worker_unfolding TopLevelFlag
top_lvl CoreBndr
work_id CoreExpr
work_rhs
      = case IdInfo -> Unfolding
realUnfoldingInfo IdInfo
info of -- NB: the real one, even for loop-breakers
           unf :: Unfolding
unf@(CoreUnfolding { uf_tmpl :: Unfolding -> CoreExpr
uf_tmpl = CoreExpr
unf_rhs, uf_src :: Unfolding -> UnfoldingSource
uf_src = UnfoldingSource
src })
             | UnfoldingSource -> Bool
isStableSource UnfoldingSource
src -> Unfolding -> SimplM Unfolding
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (Unfolding
unf { uf_tmpl = mkCast unf_rhs (mkSymCo co) })
           Unfolding
_ -> SimplEnv
-> TopLevelFlag
-> UnfoldingSource
-> CoreBndr
-> Bool
-> CoreExpr
-> SimplM Unfolding
mkLetUnfolding SimplEnv
env TopLevelFlag
top_lvl UnfoldingSource
VanillaSrc CoreBndr
work_id Bool
False CoreExpr
work_rhs

tryCastWorkerWrapper SimplEnv
env BindContext
_ CoreBndr
_ CoreBndr
bndr CoreExpr
rhs  -- All other bindings
  = do { String -> SDoc -> SimplM ()
traceSmpl String
"tcww:no" ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"bndr:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr
                                   , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"rhs:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> CoreExpr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreExpr
rhs ])
        ; (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> InBind -> (SimplFloats, SimplEnv)
mkFloatBind SimplEnv
env (CoreBndr -> CoreExpr -> InBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
bndr CoreExpr
rhs)) }

mkCastWrapperInlinePrag :: InlinePragma -> InlinePragma
-- See Note [Cast worker/wrapper]
mkCastWrapperInlinePrag :: InlinePragma -> InlinePragma
mkCastWrapperInlinePrag (InlinePragma { inl_inline :: InlinePragma -> InlineSpec
inl_inline = InlineSpec
fn_inl, inl_act :: InlinePragma -> Activation
inl_act = Activation
fn_act, inl_rule :: InlinePragma -> RuleMatchInfo
inl_rule = RuleMatchInfo
rule_info })
  = InlinePragma { inl_src :: SourceText
inl_src    = FastString -> SourceText
SourceText (FastString -> SourceText) -> FastString -> SourceText
forall a b. (a -> b) -> a -> b
$ String -> FastString
fsLit String
"{-# INLINE"
                 , inl_inline :: InlineSpec
inl_inline = InlineSpec
fn_inl       -- See Note [Worker/wrapper for INLINABLE functions]
                 , inl_sat :: Maybe Int
inl_sat    = Maybe Int
forall a. Maybe a
Nothing      --     in GHC.Core.Opt.WorkWrap
                 , inl_act :: Activation
inl_act    = Activation
wrap_act     -- See Note [Wrapper activation]
                 , inl_rule :: RuleMatchInfo
inl_rule   = RuleMatchInfo
rule_info }  --     in GHC.Core.Opt.WorkWrap
                                -- RuleMatchInfo is (and must be) unaffected
  where
    -- See Note [Wrapper activation] in GHC.Core.Opt.WorkWrap
    -- But simpler, because we don't need to disable during InitialPhase
    wrap_act :: Activation
wrap_act | Activation -> Bool
isNeverActive Activation
fn_act = Activation
activateDuringFinal
             | Bool
otherwise            = Activation
fn_act


{- *********************************************************************
*                                                                      *
           prepareBinding, prepareRhs, makeTrivial
*                                                                      *
********************************************************************* -}

prepareBinding :: SimplEnv -> TopLevelFlag -> RecFlag -> Bool
               -> Id   -- Used only for its OccName; can be InId or OutId
               -> SimplFloats -> OutExpr
               -> SimplM (SimplFloats, OutExpr)
-- In (prepareBinding ... bndr floats rhs), the binding is really just
--    bndr = let floats in rhs
-- Maybe we can ANF-ise this binding and float out; e.g.
--    bndr = let a = f x in K a a (g x)
-- we could float out to give
--    a    = f x
--    tmp  = g x
--    bndr = K a a tmp
-- That's what prepareBinding does
-- Precondition: binder is not a JoinId
-- Postcondition: the returned SimplFloats contains only let-floats
prepareBinding :: SimplEnv
-> TopLevelFlag
-> RecFlag
-> Bool
-> CoreBndr
-> SimplFloats
-> CoreExpr
-> SimplM (SimplFloats, CoreExpr)
prepareBinding SimplEnv
env TopLevelFlag
top_lvl RecFlag
is_rec Bool
strict_bind CoreBndr
bndr SimplFloats
rhs_floats CoreExpr
rhs
  = do { -- Never float join-floats out of a non-join let-binding (which this is)
         -- So wrap the body in the join-floats right now
         -- Hence: rhs_floats1 consists only of let-floats
         let (SimplFloats
rhs_floats1, CoreExpr
rhs1) = SimplFloats -> CoreExpr -> (SimplFloats, CoreExpr)
wrapJoinFloatsX SimplFloats
rhs_floats CoreExpr
rhs

         -- rhs_env: add to in-scope set the binders from rhs_floats
         -- so that prepareRhs knows what is in scope in rhs
       ; let rhs_env :: SimplEnv
rhs_env = SimplEnv
env SimplEnv -> SimplFloats -> SimplEnv
`setInScopeFromF` SimplFloats
rhs_floats1
             -- Force the occ_fs so that the old Id is not retained in the new Id.
             !occ_fs :: FastString
occ_fs = CoreBndr -> FastString
forall a. NamedThing a => a -> FastString
getOccFS CoreBndr
bndr

       -- Now ANF-ise the remaining rhs
       ; (anf_floats, rhs2) <- HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
prepareRhs SimplEnv
rhs_env TopLevelFlag
top_lvl FastString
occ_fs CoreExpr
rhs1

       -- Finally, decide whether or not to float
       ; let all_floats = SimplFloats
rhs_floats1 SimplFloats -> LetFloats -> SimplFloats
`addLetFloats` LetFloats
anf_floats
       ; if doFloatFromRhs (seFloatEnable env) top_lvl is_rec strict_bind all_floats rhs2
         then -- Float!
              do { tick LetFloatFromLet
                 ; return (all_floats, rhs2) }

         else -- Abandon floating altogether; revert to original rhs
              -- Since we have already built rhs1, we just need to add
              -- rhs_floats1 to it
              return (emptyFloats env, wrapFloats rhs_floats1 rhs1) }

{- Note [prepareRhs]
~~~~~~~~~~~~~~~~~~~~
prepareRhs takes a putative RHS, checks whether it's a PAP or
constructor application and, if so, converts it to ANF, so that the
resulting thing can be inlined more easily.  Thus
        x = (f a, g b)
becomes
        t1 = f a
        t2 = g b
        x = (t1,t2)

We also want to deal well cases like this
        v = (f e1 `cast` co) e2
Here we want to make e1,e2 trivial and get
        x1 = e1; x2 = e2; v = (f x1 `cast` co) v2
That's what the 'go' loop in prepareRhs does
-}

prepareRhs :: HasDebugCallStack
           => SimplEnv -> TopLevelFlag
           -> FastString    -- Base for any new variables
           -> OutExpr
           -> SimplM (LetFloats, OutExpr)
-- Transforms a RHS into a better RHS by ANF'ing args
-- for expandable RHSs: constructors and PAPs
-- e.g        x = Just e
-- becomes    a = e               -- 'a' is fresh
--            x = Just a
-- See Note [prepareRhs]
prepareRhs :: HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
prepareRhs SimplEnv
env TopLevelFlag
top_lvl FastString
occ CoreExpr
rhs0
  | Bool
is_expandable = CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
rhs0
  | Bool
otherwise     = (LetFloats, CoreExpr) -> SimplM (LetFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (LetFloats
emptyLetFloats, CoreExpr
rhs0)
  where
    -- We can't use exprIsExpandable because the WHOLE POINT is that
    -- we want to treat (K <big>) as expandable, because we are just
    -- about "anfise" the <big> expression.  exprIsExpandable would
    -- just say no!
    is_expandable :: Bool
is_expandable = CoreExpr -> Int -> Bool
forall {b}. Expr b -> Int -> Bool
go CoreExpr
rhs0 Int
0
       where
         go :: Expr b -> Int -> Bool
go (Var CoreBndr
fun) Int
n_val_args       = CheapAppFun
isExpandableApp CoreBndr
fun Int
n_val_args
         go (App Expr b
fun Expr b
arg) Int
n_val_args
           | Expr b -> Bool
forall {b}. Expr b -> Bool
isTypeArg Expr b
arg             = Expr b -> Int -> Bool
go Expr b
fun Int
n_val_args
           | Bool
otherwise                 = Expr b -> Int -> Bool
go Expr b
fun (Int
n_val_args Int -> Int -> Int
forall a. Num a => a -> a -> a
+ Int
1)
         go (Cast Expr b
rhs CoercionR
_)  Int
n_val_args   = Expr b -> Int -> Bool
go Expr b
rhs Int
n_val_args
         go (Tick CoreTickish
_ Expr b
rhs)  Int
n_val_args   = Expr b -> Int -> Bool
go Expr b
rhs Int
n_val_args
         go Expr b
_             Int
_            = Bool
False

    anfise :: OutExpr -> SimplM (LetFloats, OutExpr)
    anfise :: CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise (Cast CoreExpr
rhs CoercionR
co)
        = do { (floats, rhs') <- CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
rhs
             ; return (floats, Cast rhs' co) }
    anfise (App CoreExpr
fun (Type Kind
ty))
        = do { (floats, rhs') <- CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
fun
             ; return (floats, App rhs' (Type ty)) }
    anfise (App CoreExpr
fun CoreExpr
arg)
        = do { (floats1, fun') <- CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
fun
             ; (floats2, arg') <- makeTrivial env top_lvl topDmd occ arg
             ; return (floats1 `addLetFlts` floats2, App fun' arg') }
    anfise (Var CoreBndr
fun)
        = (LetFloats, CoreExpr) -> SimplM (LetFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (LetFloats
emptyLetFloats, CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
fun)

    anfise (Tick CoreTickish
t CoreExpr
rhs)
        -- We want to be able to float bindings past this
        -- tick. Non-scoping ticks don't care.
        | CoreTickish -> TickishScoping
forall (pass :: TickishPass). GenTickish pass -> TickishScoping
tickishScoped CoreTickish
t TickishScoping -> TickishScoping -> Bool
forall a. Eq a => a -> a -> Bool
== TickishScoping
NoScope
        = do { (floats, rhs') <- CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
rhs
             ; return (floats, Tick t rhs') }

        -- On the other hand, for scoping ticks we need to be able to
        -- copy them on the floats, which in turn is only allowed if
        -- we can obtain non-counting ticks.
        | (Bool -> Bool
not (CoreTickish -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishCounts CoreTickish
t) Bool -> Bool -> Bool
|| CoreTickish -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishCanSplit CoreTickish
t)
        = do { (floats, rhs') <- CoreExpr -> SimplM (LetFloats, CoreExpr)
anfise CoreExpr
rhs
             ; let tickIt (CoreBndr
id, CoreExpr
expr) = (CoreBndr
id, CoreTickish -> CoreExpr -> CoreExpr
mkTick (CoreTickish -> CoreTickish
forall (pass :: TickishPass). GenTickish pass -> GenTickish pass
mkNoCount CoreTickish
t) CoreExpr
expr)
                   floats' = LetFloats
-> ((CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr)) -> LetFloats
mapLetFloats LetFloats
floats (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr)
tickIt
             ; return (floats', Tick t rhs') }

    anfise CoreExpr
other = (LetFloats, CoreExpr) -> SimplM (LetFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (LetFloats
emptyLetFloats, CoreExpr
other)

makeTrivialArg :: HasDebugCallStack => SimplEnv -> ArgSpec -> SimplM (LetFloats, ArgSpec)
makeTrivialArg :: HasDebugCallStack =>
SimplEnv -> ArgSpec -> SimplM (LetFloats, ArgSpec)
makeTrivialArg SimplEnv
env arg :: ArgSpec
arg@(ValArg { as_arg :: ArgSpec -> CoreExpr
as_arg = CoreExpr
e, as_dmd :: ArgSpec -> Demand
as_dmd = Demand
dmd })
  = do { (floats, e') <- HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> Demand
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
SimplEnv
-> TopLevelFlag
-> Demand
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
makeTrivial SimplEnv
env TopLevelFlag
NotTopLevel Demand
dmd (String -> FastString
fsLit String
"arg") CoreExpr
e
       ; return (floats, arg { as_arg = e' }) }
makeTrivialArg SimplEnv
_ ArgSpec
arg
  = (LetFloats, ArgSpec) -> SimplM (LetFloats, ArgSpec)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (LetFloats
emptyLetFloats, ArgSpec
arg)  -- CastBy, TyArg

makeTrivial :: HasDebugCallStack
            => SimplEnv -> TopLevelFlag -> Demand
            -> FastString  -- ^ A "friendly name" to build the new binder from
            -> OutExpr
            -> SimplM (LetFloats, OutExpr)
-- Binds the expression to a variable, if it's not trivial, returning the variable
-- For the Demand argument, see Note [Keeping demand info in StrictArg Plan A]
makeTrivial :: HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> Demand
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
makeTrivial SimplEnv
env TopLevelFlag
top_lvl Demand
dmd FastString
occ_fs CoreExpr
expr
  | CoreExpr -> Bool
exprIsTrivial CoreExpr
expr                          -- Already trivial
  Bool -> Bool -> Bool
|| Bool -> Bool
not (TopLevelFlag -> CoreExpr -> Kind -> Bool
bindingOk TopLevelFlag
top_lvl CoreExpr
expr Kind
expr_ty)       -- Cannot trivialise
                                                --   See Note [Cannot trivialise]
  = (LetFloats, CoreExpr) -> SimplM (LetFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (LetFloats
emptyLetFloats, CoreExpr
expr)

  | Cast CoreExpr
expr' CoercionR
co <- CoreExpr
expr
  = do { (floats, triv_expr) <- HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> Demand
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
SimplEnv
-> TopLevelFlag
-> Demand
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
makeTrivial SimplEnv
env TopLevelFlag
top_lvl Demand
dmd FastString
occ_fs CoreExpr
expr'
       ; return (floats, Cast triv_expr co) }

  | Bool
otherwise -- 'expr' is not of form (Cast e co)
  = do  { (floats, expr1) <- HasDebugCallStack =>
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
SimplEnv
-> TopLevelFlag
-> FastString
-> CoreExpr
-> SimplM (LetFloats, CoreExpr)
prepareRhs SimplEnv
env TopLevelFlag
top_lvl FastString
occ_fs CoreExpr
expr
        ; uniq <- getUniqueM
        ; let name = Unique -> FastString -> Name
mkSystemVarName Unique
uniq FastString
occ_fs
              var  = HasDebugCallStack => Name -> Kind -> Kind -> IdInfo -> CoreBndr
Name -> Kind -> Kind -> IdInfo -> CoreBndr
mkLocalIdWithInfo Name
name Kind
ManyTy Kind
expr_ty IdInfo
id_info

        -- Now something very like completeBind,
        -- but without the postInlineUnconditionally part
        ; (arity_type, expr2) <- tryEtaExpandRhs env (BC_Let top_lvl NonRecursive) var expr1
          -- Technically we should extend the in-scope set in 'env' with
          -- the 'floats' from prepareRHS; but they are all fresh, so there is
          -- no danger of introducing name shadowing in eta expansion

        ; unf <- mkLetUnfolding env top_lvl VanillaSrc var False expr2

        ; let final_id = CoreBndr -> ArityType -> Unfolding -> CoreBndr
addLetBndrInfo CoreBndr
var ArityType
arity_type Unfolding
unf
              bind     = CoreBndr -> CoreExpr -> InBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
final_id CoreExpr
expr2

        ; traceSmpl "makeTrivial" (vcat [text "final_id" <+> ppr final_id, text "rhs" <+> ppr expr2 ])
        ; return ( floats `addLetFlts` unitLetFloat bind, Var final_id ) }
  where
    id_info :: IdInfo
id_info = IdInfo
vanillaIdInfo IdInfo -> Demand -> IdInfo
`setDemandInfo` Demand
dmd
    expr_ty :: Kind
expr_ty = HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
expr

bindingOk :: TopLevelFlag -> CoreExpr -> Type -> Bool
-- True iff we can have a binding of this expression at this level
-- Precondition: the type is the type of the expression
bindingOk :: TopLevelFlag -> CoreExpr -> Kind -> Bool
bindingOk TopLevelFlag
top_lvl CoreExpr
expr Kind
expr_ty
  | TopLevelFlag -> Bool
isTopLevel TopLevelFlag
top_lvl = CoreExpr -> Kind -> Bool
exprIsTopLevelBindable CoreExpr
expr Kind
expr_ty
  | Bool
otherwise          = Bool
True

{- Note [Cannot trivialise]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider:
   f :: Int -> Addr#

   foo :: Bar
   foo = Bar (f 3)

Then we can't ANF-ise foo, even though we'd like to, because
we can't make a top-level binding for the Addr# (f 3). And if
so we don't want to turn it into
   foo = let x = f 3 in Bar x
because we'll just end up inlining x back, and that makes the
simplifier loop.  Better not to ANF-ise it at all.

Literal strings are an exception.

   foo = Ptr "blob"#

We want to turn this into:

   foo1 = "blob"#
   foo = Ptr foo1

See Note [Core top-level string literals] in GHC.Core.

************************************************************************
*                                                                      *
          Completing a lazy binding
*                                                                      *
************************************************************************

completeBind
  * deals only with Ids, not TyVars
  * takes an already-simplified binder and RHS
  * is used for both recursive and non-recursive bindings
  * is used for both top-level and non-top-level bindings

It does the following:
  - tries discarding a dead binding
  - tries PostInlineUnconditionally
  - add unfolding [this is the only place we add an unfolding]
  - add arity
  - extend the InScopeSet of the SimplEnv

It does *not* attempt to do let-to-case.  Why?  Because it is used for
  - top-level bindings (when let-to-case is impossible)
  - many situations where the "rhs" is known to be a WHNF
                (so let-to-case is inappropriate).

Nor does it do the atomic-argument thing
-}

completeBind :: BindContext
             -> (InId, SimplEnv)           -- Old binder, and the static envt in which to simplify
                                           --   its stable unfolding (if any)
             -> (OutId, OutExpr, SimplEnv) -- New binder and rhs; can be a JoinId.
                                           -- And the SimplEnv with that OutId in scope.
             -> SimplM (SimplFloats, SimplEnv)
-- completeBind may choose to do its work
--      * by extending the substitution (e.g. let x = y in ...)
--      * or by adding to the floats in the envt
--
-- Binder /can/ be a JoinId
-- Precondition: rhs obeys the let-can-float invariant
completeBind :: BindContext
-> (CoreBndr, SimplEnv)
-> (CoreBndr, CoreExpr, SimplEnv)
-> SimplM (SimplFloats, SimplEnv)
completeBind BindContext
bind_cxt (CoreBndr
old_bndr, SimplEnv
unf_se) (CoreBndr
new_bndr, CoreExpr
new_rhs, SimplEnv
env)
 | CoreBndr -> Bool
isCoVar CoreBndr
old_bndr
 = case CoreExpr
new_rhs of
     Coercion CoercionR
co -> (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, SimplEnv -> CoreBndr -> CoercionR -> SimplEnv
extendCvSubst SimplEnv
env CoreBndr
old_bndr CoercionR
co)
     CoreExpr
_           -> (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> InBind -> (SimplFloats, SimplEnv)
mkFloatBind SimplEnv
env (CoreBndr -> CoreExpr -> InBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
new_bndr CoreExpr
new_rhs))

 | Bool
otherwise
 = Bool
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a. HasCallStack => Bool -> a -> a
assert (CoreBndr -> Bool
isId CoreBndr
new_bndr) (SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv))
-> SimplM (SimplFloats, SimplEnv) -> SimplM (SimplFloats, SimplEnv)
forall a b. (a -> b) -> a -> b
$
   do { let old_info :: IdInfo
old_info = HasDebugCallStack => CoreBndr -> IdInfo
CoreBndr -> IdInfo
idInfo CoreBndr
old_bndr
            old_unf :: Unfolding
old_unf  = IdInfo -> Unfolding
realUnfoldingInfo IdInfo
old_info

         -- Do eta-expansion on the RHS of the binding
         -- See Note [Eta-expanding at let bindings] in GHC.Core.Opt.Simplify.Utils
      ; (new_arity, eta_rhs) <- SimplEnv
-> BindContext
-> CoreBndr
-> CoreExpr
-> SimplM (ArityType, CoreExpr)
tryEtaExpandRhs SimplEnv
env BindContext
bind_cxt CoreBndr
new_bndr CoreExpr
new_rhs

        -- Simplify the unfolding; see Note [Environment for simplLetUnfolding]
      ; new_unfolding <- simplLetUnfolding (unf_se `setInScopeFromE` env)
                            bind_cxt old_bndr
                            eta_rhs (idType new_bndr) new_arity old_unf

      ; let new_bndr_w_info = CoreBndr -> ArityType -> Unfolding -> CoreBndr
addLetBndrInfo CoreBndr
new_bndr ArityType
new_arity Unfolding
new_unfolding
        -- See Note [In-scope set as a substitution]

      ; if postInlineUnconditionally env bind_cxt old_bndr new_bndr_w_info eta_rhs

        then -- Inline and discard the binding
             do  { tick (PostInlineUnconditionally old_bndr)
                 ; let unf_rhs = Unfolding -> Maybe CoreExpr
maybeUnfoldingTemplate Unfolding
new_unfolding Maybe CoreExpr -> CoreExpr -> CoreExpr
forall a. Maybe a -> a -> a
`orElse` CoreExpr
eta_rhs
                          -- See Note [Use occ-anald RHS in postInlineUnconditionally]
                 ; simplTrace "PostInlineUnconditionally" (ppr new_bndr <+> ppr unf_rhs) $
                   return ( emptyFloats env
                          , extendIdSubst env old_bndr $
                            DoneEx unf_rhs (idJoinPointHood new_bndr)) }
                -- Use the substitution to make quite, quite sure that the
                -- substitution will happen, since we are going to discard the binding

        else -- Keep the binding; do cast worker/wrapper
--             simplTrace "completeBind" (vcat [ text "bndrs" <+> ppr old_bndr <+> ppr new_bndr
--                                             , text "eta_rhs" <+> ppr eta_rhs ]) $
             tryCastWorkerWrapper env bind_cxt old_bndr new_bndr_w_info eta_rhs }

addLetBndrInfo :: OutId -> ArityType -> Unfolding -> OutId
addLetBndrInfo :: CoreBndr -> ArityType -> Unfolding -> CoreBndr
addLetBndrInfo CoreBndr
new_bndr ArityType
new_arity_type Unfolding
new_unf
  = CoreBndr
new_bndr CoreBndr -> IdInfo -> CoreBndr
`setIdInfo` IdInfo
info5
  where
    new_arity :: Int
new_arity = ArityType -> Int
arityTypeArity ArityType
new_arity_type
    info1 :: IdInfo
info1 = HasDebugCallStack => CoreBndr -> IdInfo
CoreBndr -> IdInfo
idInfo CoreBndr
new_bndr IdInfo -> Int -> IdInfo
`setArityInfo` Int
new_arity

    -- Unfolding info: Note [Setting the new unfolding]
    info2 :: IdInfo
info2 = IdInfo
info1 IdInfo -> Unfolding -> IdInfo
`setUnfoldingInfo` Unfolding
new_unf

    -- Demand info: Note [Setting the demand info]
    info3 :: IdInfo
info3 | Unfolding -> Bool
isEvaldUnfolding Unfolding
new_unf
          = IdInfo -> Maybe IdInfo
lazifyDemandInfo IdInfo
info2 Maybe IdInfo -> IdInfo -> IdInfo
forall a. Maybe a -> a -> a
`orElse` IdInfo
info2
          | Bool
otherwise
          = IdInfo
info2

    -- Bottoming bindings: see Note [Bottoming bindings]
    info4 :: IdInfo
info4 = case ArityType -> Maybe (Int, DmdSig, CprSig)
arityTypeBotSigs_maybe ArityType
new_arity_type of
        Maybe (Int, DmdSig, CprSig)
Nothing -> IdInfo
info3
        Just (Int
ar, DmdSig
str_sig, CprSig
cpr_sig) -> Bool -> IdInfo -> IdInfo
forall a. HasCallStack => Bool -> a -> a
assert (Int
ar Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
new_arity) (IdInfo -> IdInfo) -> IdInfo -> IdInfo
forall a b. (a -> b) -> a -> b
$
                                       IdInfo
info3 IdInfo -> DmdSig -> IdInfo
`setDmdSigInfo` DmdSig
str_sig
                                             IdInfo -> CprSig -> IdInfo
`setCprSigInfo` CprSig
cpr_sig

     -- Zap call arity info. We have used it by now (via
     -- `tryEtaExpandRhs`), and the simplifier can invalidate this
     -- information, leading to broken code later (e.g. #13479)
    info5 :: IdInfo
info5 = IdInfo -> IdInfo
zapCallArityInfo IdInfo
info4


{- Note [Bottoming bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have
   let x = error "urk"
   in ...(case x of <alts>)...
or
   let f = \y. error (y ++ "urk")
   in ...(case f "foo" of <alts>)...

Then we'd like to drop the dead <alts> immediately.  So it's good to
propagate the info that x's (or f's) RHS is bottom to x's (or f's)
IdInfo as rapidly as possible.

We use tryEtaExpandRhs on every binding, and it turns out that the
arity computation it performs (via GHC.Core.Opt.Arity.findRhsArity) already
does a simple bottoming-expression analysis.  So all we need to do
is propagate that info to the binder's IdInfo.

This showed up in #12150; see comment:16.

There is a second reason for settting  the strictness signature. Consider
   let -- f :: <[S]b>
       f = \x. error "urk"
   in ...(f a b c)...
Then, in GHC.Core.Opt.Arity.findRhsArity we'll use the demand-info on `f`
to eta-expand to
   let f = \x y z. error "urk"
   in ...(f a b c)...

But now f's strictness signature has too short an arity; see
GHC.Core.Opt.DmdAnal Note [idArity varies independently of dmdTypeDepth].
Fortuitously, the same strictness-signature-fixup code
gives the function a new strictness signature with the right number of
arguments.  Example in stranal/should_compile/EtaExpansion.

Note [Setting the demand info]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the unfolding is a value, the demand info may
go pear-shaped, so we nuke it.  Example:
     let x = (a,b) in
     case x of (p,q) -> h p q x
Here x is certainly demanded. But after we've nuked
the case, we'll get just
     let x = (a,b) in h a b x
and now x is not demanded (I'm assuming h is lazy)
This really happens.  Similarly
     let f = \x -> e in ...f..f...
After inlining f at some of its call sites the original binding may
(for example) be no longer strictly demanded.
The solution here is a bit ad hoc...

Note [Use occ-anald RHS in postInlineUnconditionally]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we postInlineUnconditionally 'f in
  let f = \x -> x True in ...(f blah)...
then we'd like to inline the /occ-anald/ RHS for 'f'.  If we
use the non-occ-anald version, we'll end up with a
    ...(let x = blah in x True)...
and hence an extra Simplifier iteration.

We already /have/ the occ-anald version in the Unfolding for
the Id.  Well, maybe not /quite/ always.  If the binder is Dead,
postInlineUnconditionally will return True, but we may not have an
unfolding because it's too big. Hence the belt-and-braces `orElse`
in the defn of unf_rhs.  The Nothing case probably never happens.

Note [Environment for simplLetUnfolding]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We need to be rather careful about the static environment in which
we simplify a stable unfolding.  Consider (#24242):

  f x = let y_Xb = ... in
        let step1_Xb {Stable unfolding = ....y_Xb...} = rhs in
         ...

Note that `y_Xb` and `step1_Xb` have the same unique (`Xb`). This can happen;
see Note [Shadowing in Core] in GHC.Core, and Note [Shadowing in the Simplifier].
This is perfectly fine. The `y_Xb` in the stable unfolding of the non-
recursive binding for `step1` refers, of course, to `let y_Xb = ....`.
When simplifying the binder `step1_Xb` we'll give it a new unique, and
extend the static environment with [Xb :-> step1_Xc], say.

But when simplifying step1's stable unfolding, we must use static environment
/before/ simplifying the binder `step1_Xb`; that is, a static envt that maps
[Xb :-> y_Xb], /not/ [Xb :-> step1_Xc].

That is why we pass around a pair `(InId, SimplEnv)` for the binder, keeping
track of the right environment for the unfolding of that InId.  See the type
of `simplLazyBind`, `simplJoinBind`, `completeBind`.

This only matters when we have
  - A non-recursive binding for f
  - has a stable unfolding
  - and that unfolding mentions a variable y
  - that has the same unique as f.
So triggering  a bug here is really hard!

************************************************************************
*                                                                      *
\subsection[Simplify-simplExpr]{The main function: simplExpr}
*                                                                      *
************************************************************************

The reason for this OutExprStuff stuff is that we want to float *after*
simplifying a RHS, not before.  If we do so naively we get quadratic
behaviour as things float out.

To see why it's important to do it after, consider this (real) example:

        let t = f x
        in fst t
==>
        let t = let a = e1
                    b = e2
                in (a,b)
        in fst t
==>
        let a = e1
            b = e2
            t = (a,b)
        in
        a       -- Can't inline a this round, cos it appears twice
==>
        e1

Each of the ==> steps is a round of simplification.  We'd save a
whole round if we float first.  This can cascade.  Consider

        let f = g d
        in \x -> ...f...
==>
        let f = let d1 = ..d.. in \y -> e
        in \x -> ...f...
==>
        let d1 = ..d..
        in \x -> ...(\y ->e)...

Only in this second round can the \y be applied, and it
might do the same again.
-}

simplExpr :: SimplEnv -> CoreExpr -> SimplM CoreExpr
simplExpr :: SimplEnv -> CoreExpr -> SimplM CoreExpr
simplExpr !SimplEnv
env (Type Kind
ty) -- See Note [Bangs in the Simplifier]
  = do { ty' <- SimplEnv -> Kind -> SimplM Kind
simplType SimplEnv
env Kind
ty  -- See Note [Avoiding space leaks in OutType]
       ; return (Type ty') }

simplExpr SimplEnv
env CoreExpr
expr
  = SimplEnv -> CoreExpr -> SimplCont -> SimplM CoreExpr
simplExprC SimplEnv
env CoreExpr
expr (Kind -> SimplCont
mkBoringStop Kind
expr_out_ty)
  where
    expr_out_ty :: OutType
    expr_out_ty :: Kind
expr_out_ty = HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
env (HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
expr)
    -- NB: Since 'expr' is term-valued, not (Type ty), this call
    --     to exprType will succeed.  exprType fails on (Type ty).

simplExprC :: SimplEnv
           -> InExpr     -- A term-valued expression, never (Type ty)
           -> SimplCont
           -> SimplM OutExpr
        -- Simplify an expression, given a continuation
simplExprC :: SimplEnv -> CoreExpr -> SimplCont -> SimplM CoreExpr
simplExprC SimplEnv
env CoreExpr
expr SimplCont
cont
  = -- pprTrace "simplExprC" (ppr expr $$ ppr cont) $
    do  { (floats, expr') <- SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
expr SimplCont
cont
        ; -- pprTrace "simplExprC ret" (ppr expr $$ ppr expr') $
          -- pprTrace "simplExprC ret3" (ppr (seInScope env')) $
          -- pprTrace "simplExprC ret4" (ppr (seLetFloats env')) $
          return (wrapFloats floats expr') }

--------------------------------------------------
simplExprF :: SimplEnv
           -> InExpr     -- A term-valued expression, never (Type ty)
           -> SimplCont
           -> SimplM (SimplFloats, OutExpr)

simplExprF :: SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF !SimplEnv
env CoreExpr
e !SimplCont
cont -- See Note [Bangs in the Simplifier]
  = {- pprTrace "simplExprF" (vcat
      [ ppr e
      , text "cont =" <+> ppr cont
      , text "inscope =" <+> ppr (seInScope env)
      , text "tvsubst =" <+> ppr (seTvSubst env)
      , text "idsubst =" <+> ppr (seIdSubst env)
      , text "cvsubst =" <+> ppr (seCvSubst env)
      ]) $ -}
    HasDebugCallStack =>
SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF1 SimplEnv
env CoreExpr
e SimplCont
cont

simplExprF1 :: HasDebugCallStack
            => SimplEnv -> InExpr -> SimplCont
            -> SimplM (SimplFloats, OutExpr)

simplExprF1 :: HasDebugCallStack =>
SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF1 SimplEnv
_ (Type Kind
ty) SimplCont
cont
  = String -> SDoc -> SimplM (SimplFloats, CoreExpr)
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"simplExprF: type" (Kind -> SDoc
forall a. Outputable a => a -> SDoc
ppr Kind
ty SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> String -> SDoc
forall doc. IsLine doc => String -> doc
textString
"cont: " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SimplCont -> SDoc
forall a. Outputable a => a -> SDoc
ppr SimplCont
cont)
    -- simplExprF does only with term-valued expressions
    -- The (Type ty) case is handled separately by simplExpr
    -- and by the other callers of simplExprF

simplExprF1 SimplEnv
env (Var CoreBndr
v)        SimplCont
cont = {-#SCC "simplIdF" #-} SimplEnv -> CoreBndr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplIdF SimplEnv
env CoreBndr
v SimplCont
cont
simplExprF1 SimplEnv
env (Lit Literal
lit)      SimplCont
cont = {-#SCC "rebuild" #-} SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (Literal -> CoreExpr
forall b. Literal -> Expr b
Lit Literal
lit) SimplCont
cont
simplExprF1 SimplEnv
env (Tick CoreTickish
t CoreExpr
expr)  SimplCont
cont = {-#SCC "simplTick" #-} SimplEnv
-> CoreTickish
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplTick SimplEnv
env CoreTickish
t CoreExpr
expr SimplCont
cont
simplExprF1 SimplEnv
env (Cast CoreExpr
body CoercionR
co) SimplCont
cont = {-#SCC "simplCast" #-} SimplEnv
-> CoreExpr
-> CoercionR
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplCast SimplEnv
env CoreExpr
body CoercionR
co SimplCont
cont
simplExprF1 SimplEnv
env (Coercion CoercionR
co)  SimplCont
cont = {-#SCC "simplCoercionF" #-} SimplEnv
-> CoercionR -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplCoercionF SimplEnv
env CoercionR
co SimplCont
cont

simplExprF1 SimplEnv
env (App CoreExpr
fun CoreExpr
arg) SimplCont
cont
  = {-#SCC "simplExprF1-App" #-} case CoreExpr
arg of
      Type Kind
ty -> do { -- The argument type will (almost) certainly be used
                      -- in the output program, so just force it now.
                      -- See Note [Avoiding space leaks in OutType]
                      arg' <- SimplEnv -> Kind -> SimplM Kind
simplType SimplEnv
env Kind
ty

                      -- But use substTy, not simplType, to avoid forcing
                      -- the hole type; it will likely not be needed.
                      -- See Note [The hole type in ApplyToTy]
                    ; let hole' = HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
env (HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
fun)

                    ; simplExprF env fun $
                      ApplyToTy { sc_arg_ty  = arg'
                                , sc_hole_ty = hole'
                                , sc_cont    = cont } }
      CoreExpr
_       ->
          -- Crucially, sc_hole_ty is a /lazy/ binding.  It will
          -- be forced only if we need to run contHoleType.
          -- When these are forced, we might get quadratic behavior;
          -- this quadratic blowup could be avoided by drilling down
          -- to the function and getting its multiplicities all at once
          -- (instead of one-at-a-time). But in practice, we have not
          -- observed the quadratic behavior, so this extra entanglement
          -- seems not worthwhile.
        SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
fun (SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplCont -> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$
        ApplyToVal { sc_arg :: CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplEnv
sc_env = SimplEnv
env
                   , sc_hole_ty :: Kind
sc_hole_ty = HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
env (HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
fun)
                   , sc_dup :: DupFlag
sc_dup = DupFlag
NoDup, sc_cont :: SimplCont
sc_cont = SimplCont
cont }

simplExprF1 SimplEnv
env expr :: CoreExpr
expr@(Lam {}) SimplCont
cont
  = {-#SCC "simplExprF1-Lam" #-}
    SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam SimplEnv
env (CoreExpr -> Int -> CoreExpr
zapLambdaBndrs CoreExpr
expr Int
n_args) SimplCont
cont
        -- zapLambdaBndrs: the issue here is under-saturated lambdas
        --   (\x1. \x2. e) arg1
        -- Here x1 might have "occurs-once" occ-info, because occ-info
        -- is computed assuming that a group of lambdas is applied
        -- all at once.  If there are too few args, we must zap the
        -- occ-info, UNLESS the remaining binders are one-shot
  where
    n_args :: Int
n_args = SimplCont -> Int
countArgs SimplCont
cont
        -- NB: countArgs counts all the args (incl type args)
        -- and likewise drop counts all binders (incl type lambdas)

simplExprF1 SimplEnv
env (Case CoreExpr
scrut CoreBndr
bndr Kind
_ [Alt CoreBndr]
alts) SimplCont
cont
  = {-#SCC "simplExprF1-Case" #-}
    SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
scrut (Select { sc_dup :: DupFlag
sc_dup = DupFlag
NoDup, sc_bndr :: CoreBndr
sc_bndr = CoreBndr
bndr
                                 , sc_alts :: [Alt CoreBndr]
sc_alts = [Alt CoreBndr]
alts
                                 , sc_env :: SimplEnv
sc_env = SimplEnv
env, sc_cont :: SimplCont
sc_cont = SimplCont
cont })

simplExprF1 SimplEnv
env (Let (Rec [(CoreBndr, CoreExpr)]
pairs) CoreExpr
body) SimplCont
cont
  | Just [(CoreBndr, CoreExpr)]
pairs' <- [(CoreBndr, CoreExpr)] -> Maybe [(CoreBndr, CoreExpr)]
joinPointBindings_maybe [(CoreBndr, CoreExpr)]
pairs
  = {-#SCC "simplRecJoinPoin" #-} SimplEnv
-> [(CoreBndr, CoreExpr)]
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplRecJoinPoint SimplEnv
env [(CoreBndr, CoreExpr)]
pairs' CoreExpr
body SimplCont
cont

  | Bool
otherwise
  = {-#SCC "simplRecE" #-} SimplEnv
-> [(CoreBndr, CoreExpr)]
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplRecE SimplEnv
env [(CoreBndr, CoreExpr)]
pairs CoreExpr
body SimplCont
cont

simplExprF1 SimplEnv
env (Let (NonRec CoreBndr
bndr CoreExpr
rhs) CoreExpr
body) SimplCont
cont
  | Type Kind
ty <- CoreExpr
rhs    -- First deal with type lets (let a = Type ty in e)
  = {-#SCC "simplExprF1-NonRecLet-Type" #-}
    Bool
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a. HasCallStack => Bool -> a -> a
assert (CoreBndr -> Bool
isTyVar CoreBndr
bndr) (SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$
    do { ty' <- SimplEnv -> Kind -> SimplM Kind
simplType SimplEnv
env Kind
ty
       ; simplExprF (extendTvSubst env bndr ty') body cont }

  | Just SimplEnv
env' <- SimplEnv
-> TopLevelFlag
-> CoreBndr
-> CoreExpr
-> SimplEnv
-> Maybe SimplEnv
preInlineUnconditionally SimplEnv
env TopLevelFlag
NotTopLevel CoreBndr
bndr CoreExpr
rhs SimplEnv
env
    -- Because of the let-can-float invariant, it's ok to
    -- inline freely, or to drop the binding if it is dead.
  = do { Tick -> SimplM ()
tick (CoreBndr -> Tick
PreInlineUnconditionally CoreBndr
bndr)
       ; SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env' CoreExpr
body SimplCont
cont }

  -- Now check for a join point.  It's better to do the preInlineUnconditionally
  -- test first, because joinPointBinding_maybe has to eta-expand, so a trivial
  -- binding like { j = j2 |> co } would first be eta-expanded and then inlined
  -- Better to test preInlineUnconditionally first.
  | Just (CoreBndr
bndr', CoreExpr
rhs') <- CoreBndr -> CoreExpr -> Maybe (CoreBndr, CoreExpr)
joinPointBinding_maybe CoreBndr
bndr CoreExpr
rhs
  = {-#SCC "simplNonRecJoinPoint" #-}
    SimplEnv
-> CoreBndr
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecJoinPoint SimplEnv
env CoreBndr
bndr' CoreExpr
rhs' CoreExpr
body SimplCont
cont

  | Bool
otherwise
  = {-#SCC "simplNonRecE" #-}
    HasDebugCallStack =>
SimplEnv
-> FromWhat
-> CoreBndr
-> (CoreExpr, SimplEnv)
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
SimplEnv
-> FromWhat
-> CoreBndr
-> (CoreExpr, SimplEnv)
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecE SimplEnv
env FromWhat
FromLet CoreBndr
bndr (CoreExpr
rhs, SimplEnv
env) CoreExpr
body SimplCont
cont

{- Note [Avoiding space leaks in OutType]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Since the simplifier is run for multiple iterations, we need to ensure
that any thunks in the output of one simplifier iteration are forced
by the evaluation of the next simplifier iteration. Otherwise we may
retain multiple copies of the Core program and leak a terrible amount
of memory (as in #13426).

The simplifier is naturally strict in the entire "Expr part" of the
input Core program, because any expression may contain binders, which
we must find in order to extend the SimplEnv accordingly. But types
do not contain binders and so it is tempting to write things like

    simplExpr env (Type ty) = return (Type (substTy env ty))   -- Bad!

This is Bad because the result includes a thunk (substTy env ty) which
retains a reference to the whole simplifier environment; and the next
simplifier iteration will not force this thunk either, because the
line above is not strict in ty.

So instead our strategy is for the simplifier to fully evaluate
OutTypes when it emits them into the output Core program, for example

    simplExpr env (Type ty) = do { ty' <- simplType env ty     -- Good
                                 ; return (Type ty') }

where the only difference from above is that simplType calls seqType
on the result of substTy.

However, SimplCont can also contain OutTypes and it's not necessarily
a good idea to force types on the way in to SimplCont, because they
may end up not being used and forcing them could be a lot of wasted
work. T5631 is a good example of this.

- For ApplyToTy's sc_arg_ty, we force the type on the way in because
  the type will almost certainly appear as a type argument in the
  output program.

- For the hole types in Stop and ApplyToTy, we force the type when we
  emit it into the output program, after obtaining it from
  contResultType. (The hole type in ApplyToTy is only directly used
  to form the result type in a new Stop continuation.)
-}

---------------------------------
-- Simplify a join point, adding the context.
-- Context goes *inside* the lambdas. IOW, if the join point has arity n, we do:
--   \x1 .. xn -> e => \x1 .. xn -> E[e]
-- Note that we need the arity of the join point, since e may be a lambda
-- (though this is unlikely). See Note [Join points and case-of-case].
simplJoinRhs :: SimplEnv -> InId -> InExpr -> SimplCont
             -> SimplM OutExpr
simplJoinRhs :: SimplEnv -> CoreBndr -> CoreExpr -> SimplCont -> SimplM CoreExpr
simplJoinRhs SimplEnv
env CoreBndr
bndr CoreExpr
expr SimplCont
cont
  | JoinPoint Int
arity <- CoreBndr -> JoinPointHood
idJoinPointHood CoreBndr
bndr
  =  do { let ([CoreBndr]
join_bndrs, CoreExpr
join_body) = Int -> CoreExpr -> ([CoreBndr], CoreExpr)
forall b. Int -> Expr b -> ([b], Expr b)
collectNBinders Int
arity CoreExpr
expr
              mult :: Kind
mult = SimplCont -> Kind
contHoleScaling SimplCont
cont
        ; (env', join_bndrs') <- SimplEnv -> [CoreBndr] -> SimplM (SimplEnv, [CoreBndr])
simplLamBndrs SimplEnv
env ((CoreBndr -> CoreBndr) -> [CoreBndr] -> [CoreBndr]
forall a b. (a -> b) -> [a] -> [b]
map (Kind -> CoreBndr -> CoreBndr
scaleVarBy Kind
mult) [CoreBndr]
join_bndrs)
        ; join_body' <- simplExprC env' join_body cont
        ; return $ mkLams join_bndrs' join_body' }

  | Bool
otherwise
  = String -> SDoc -> SimplM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"simplJoinRhs" (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr)

---------------------------------
simplType :: SimplEnv -> InType -> SimplM OutType
        -- Kept monadic just so we can do the seqType
        -- See Note [Avoiding space leaks in OutType]
simplType :: SimplEnv -> Kind -> SimplM Kind
simplType SimplEnv
env Kind
ty
  = -- pprTrace "simplType" (ppr ty $$ ppr (seTvSubst env)) $
    Kind -> ()
seqType Kind
new_ty () -> SimplM Kind -> SimplM Kind
forall a b. a -> b -> b
`seq` Kind -> SimplM Kind
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return Kind
new_ty
  where
    new_ty :: Kind
new_ty = HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
env Kind
ty

---------------------------------
simplCoercionF :: SimplEnv -> InCoercion -> SimplCont
               -> SimplM (SimplFloats, OutExpr)
simplCoercionF :: SimplEnv
-> CoercionR -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplCoercionF SimplEnv
env CoercionR
co SimplCont
cont
  = do { co' <- SimplEnv -> CoercionR -> SimplM CoercionR
simplCoercion SimplEnv
env CoercionR
co
       ; rebuild env (Coercion co') cont }

simplCoercion :: SimplEnv -> InCoercion -> SimplM OutCoercion
simplCoercion :: SimplEnv -> CoercionR -> SimplM CoercionR
simplCoercion SimplEnv
env CoercionR
co
  = do { let opt_co :: CoercionR
opt_co | SimplEnv -> Bool
reSimplifying SimplEnv
env = SimplEnv -> CoercionR -> CoercionR
substCo SimplEnv
env CoercionR
co
                    | Bool
otherwise         = OptCoercionOpts -> Subst -> CoercionR -> CoercionR
optCoercion OptCoercionOpts
opts Subst
subst CoercionR
co
             -- If (reSimplifying env) is True we have already simplified
             -- this coercion once, and we don't want do so again; doing
             -- so repeatedly risks non-linear behaviour
             -- See Note [Inline depth] in GHC.Core.Opt.Simplify.Env
       ; CoercionR -> ()
seqCo CoercionR
opt_co () -> SimplM CoercionR -> SimplM CoercionR
forall a b. a -> b -> b
`seq` CoercionR -> SimplM CoercionR
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return CoercionR
opt_co }
  where
    subst :: Subst
subst = SimplEnv -> Subst
getSubst SimplEnv
env
    opts :: OptCoercionOpts
opts  = SimplEnv -> OptCoercionOpts
seOptCoercionOpts SimplEnv
env

-----------------------------------
-- | Push a TickIt context outwards past applications and cases, as
-- long as this is a non-scoping tick, to let case and application
-- optimisations apply.

simplTick :: SimplEnv -> CoreTickish -> InExpr -> SimplCont
          -> SimplM (SimplFloats, OutExpr)
simplTick :: SimplEnv
-> CoreTickish
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplTick SimplEnv
env CoreTickish
tickish CoreExpr
expr SimplCont
cont
  -- A scoped tick turns into a continuation, so that we can spot
  -- (scc t (\x . e)) in simplLam and eliminate the scc.  If we didn't do
  -- it this way, then it would take two passes of the simplifier to
  -- reduce ((scc t (\x . e)) e').
  -- NB, don't do this with counting ticks, because if the expr is
  -- bottom, then rebuildCall will discard the continuation.

--------------------------
--  | tickishScoped tickish && not (tickishCounts tickish)
--  = simplExprF env expr (TickIt tickish cont)
-- XXX: we cannot do this, because the simplifier assumes that
-- the context can be pushed into a case with a single branch. e.g.
--    scc<f>  case expensive of p -> e
-- becomes
--    case expensive of p -> scc<f> e
--
-- So I'm disabling this for now.  It just means we will do more
-- simplifier iterations that necessary in some cases.
--------------------------

  -- For unscoped or soft-scoped ticks, we are allowed to float in new
  -- cost, so we simply push the continuation inside the tick.  This
  -- has the effect of moving the tick to the outside of a case or
  -- application context, allowing the normal case and application
  -- optimisations to fire.
  | CoreTickish
tickish CoreTickish -> TickishScoping -> Bool
forall (pass :: TickishPass).
GenTickish pass -> TickishScoping -> Bool
`tickishScopesLike` TickishScoping
SoftScope
  = do { (floats, expr') <- SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
expr SimplCont
cont
       ; return (floats, mkTick tickish expr')
       }

  -- Push tick inside if the context looks like this will allow us to
  -- do a case-of-case - see Note [case-of-scc-of-case]
  | Select {} <- SimplCont
cont, Just CoreExpr
expr' <- Maybe CoreExpr
push_tick_inside
  = SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
expr' SimplCont
cont

  -- We don't want to move the tick, but we might still want to allow
  -- floats to pass through with appropriate wrapping (or not, see
  -- wrap_floats below)
  --- | not (tickishCounts tickish) || tickishCanSplit tickish
  -- = wrap_floats

  | Bool
otherwise
  = SimplM (SimplFloats, CoreExpr)
no_floating_past_tick

 where

  -- Try to push tick inside a case, see Note [case-of-scc-of-case].
  push_tick_inside :: Maybe CoreExpr
push_tick_inside =
    case CoreExpr
expr0 of
      Case CoreExpr
scrut CoreBndr
bndr Kind
ty [Alt CoreBndr]
alts
             -> CoreExpr -> Maybe CoreExpr
forall a. a -> Maybe a
Just (CoreExpr -> Maybe CoreExpr) -> CoreExpr -> Maybe CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreExpr -> CoreBndr -> Kind -> [Alt CoreBndr] -> CoreExpr
forall b. Expr b -> b -> Kind -> [Alt b] -> Expr b
Case (CoreExpr -> CoreExpr
tickScrut CoreExpr
scrut) CoreBndr
bndr Kind
ty ((Alt CoreBndr -> Alt CoreBndr) -> [Alt CoreBndr] -> [Alt CoreBndr]
forall a b. (a -> b) -> [a] -> [b]
map Alt CoreBndr -> Alt CoreBndr
tickAlt [Alt CoreBndr]
alts)
      CoreExpr
_other -> Maybe CoreExpr
forall a. Maybe a
Nothing
   where ([CoreTickish]
ticks, CoreExpr
expr0) = (CoreTickish -> Bool) -> CoreExpr -> ([CoreTickish], CoreExpr)
forall b.
(CoreTickish -> Bool) -> Expr b -> ([CoreTickish], Expr b)
stripTicksTop CoreTickish -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
movable (CoreTickish -> CoreExpr -> CoreExpr
forall b. CoreTickish -> Expr b -> Expr b
Tick CoreTickish
tickish CoreExpr
expr)
         movable :: GenTickish pass -> Bool
movable GenTickish pass
t      = Bool -> Bool
not (GenTickish pass -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishCounts GenTickish pass
t) Bool -> Bool -> Bool
||
                          GenTickish pass
t GenTickish pass -> TickishScoping -> Bool
forall (pass :: TickishPass).
GenTickish pass -> TickishScoping -> Bool
`tickishScopesLike` TickishScoping
NoScope Bool -> Bool -> Bool
||
                          GenTickish pass -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishCanSplit GenTickish pass
t
         tickScrut :: CoreExpr -> CoreExpr
tickScrut CoreExpr
e    = (CoreTickish -> CoreExpr -> CoreExpr)
-> CoreExpr -> [CoreTickish] -> CoreExpr
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr CoreTickish -> CoreExpr -> CoreExpr
mkTick CoreExpr
e [CoreTickish]
ticks
         -- Alternatives get annotated with all ticks that scope in some way,
         -- but we don't want to count entries.
         tickAlt :: Alt CoreBndr -> Alt CoreBndr
tickAlt (Alt AltCon
c [CoreBndr]
bs CoreExpr
e) = AltCon -> [CoreBndr] -> CoreExpr -> Alt CoreBndr
forall b. AltCon -> [b] -> Expr b -> Alt b
Alt AltCon
c [CoreBndr]
bs ((CoreTickish -> CoreExpr -> CoreExpr)
-> CoreExpr -> [CoreTickish] -> CoreExpr
forall a b. (a -> b -> b) -> b -> [a] -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr CoreTickish -> CoreExpr -> CoreExpr
mkTick CoreExpr
e [CoreTickish]
ts_scope)
         ts_scope :: [CoreTickish]
ts_scope         = (CoreTickish -> CoreTickish) -> [CoreTickish] -> [CoreTickish]
forall a b. (a -> b) -> [a] -> [b]
map CoreTickish -> CoreTickish
forall (pass :: TickishPass). GenTickish pass -> GenTickish pass
mkNoCount ([CoreTickish] -> [CoreTickish]) -> [CoreTickish] -> [CoreTickish]
forall a b. (a -> b) -> a -> b
$
                            (CoreTickish -> Bool) -> [CoreTickish] -> [CoreTickish]
forall a. (a -> Bool) -> [a] -> [a]
filter (Bool -> Bool
not (Bool -> Bool) -> (CoreTickish -> Bool) -> CoreTickish -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (CoreTickish -> TickishScoping -> Bool
forall (pass :: TickishPass).
GenTickish pass -> TickishScoping -> Bool
`tickishScopesLike` TickishScoping
NoScope)) [CoreTickish]
ticks

  no_floating_past_tick :: SimplM (SimplFloats, CoreExpr)
no_floating_past_tick =
    do { let (SimplCont
inc,SimplCont
outc) = SimplCont -> (SimplCont, SimplCont)
splitCont SimplCont
cont
       ; (floats, expr1) <- SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
expr SimplCont
inc
       ; let expr2    = SimplFloats -> CoreExpr -> CoreExpr
wrapFloats SimplFloats
floats CoreExpr
expr1
             tickish' = SimplEnv -> CoreTickish -> CoreTickish
forall {pass :: TickishPass}.
(XTickishId pass ~ CoreBndr) =>
SimplEnv -> GenTickish pass -> GenTickish pass
simplTickish SimplEnv
env CoreTickish
tickish
       ; rebuild env (mkTick tickish' expr2) outc
       }

-- Alternative version that wraps outgoing floats with the tick.  This
-- results in ticks being duplicated, as we don't make any attempt to
-- eliminate the tick if we re-inline the binding (because the tick
-- semantics allows unrestricted inlining of HNFs), so I'm not doing
-- this any more.  FloatOut will catch any real opportunities for
-- floating.
--
--  wrap_floats =
--    do { let (inc,outc) = splitCont cont
--       ; (env', expr') <- simplExprF (zapFloats env) expr inc
--       ; let tickish' = simplTickish env tickish
--       ; let wrap_float (b,rhs) = (zapIdDmdSig (setIdArity b 0),
--                                   mkTick (mkNoCount tickish') rhs)
--              -- when wrapping a float with mkTick, we better zap the Id's
--              -- strictness info and arity, because it might be wrong now.
--       ; let env'' = addFloats env (mapFloats env' wrap_float)
--       ; rebuild env'' expr' (TickIt tickish' outc)
--       }


  simplTickish :: SimplEnv -> GenTickish pass -> GenTickish pass
simplTickish SimplEnv
env GenTickish pass
tickish
    | Breakpoint XBreakpoint pass
ext Int
n [XTickishId pass]
ids Module
modl <- GenTickish pass
tickish
          = XBreakpoint pass
-> Int -> [XTickishId pass] -> Module -> GenTickish pass
forall (pass :: TickishPass).
XBreakpoint pass
-> Int -> [XTickishId pass] -> Module -> GenTickish pass
Breakpoint XBreakpoint pass
ext Int
n ((CoreBndr -> Maybe CoreBndr) -> [CoreBndr] -> [CoreBndr]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe (SimplSR -> Maybe CoreBndr
getDoneId (SimplSR -> Maybe CoreBndr)
-> (CoreBndr -> SimplSR) -> CoreBndr -> Maybe CoreBndr
forall b c a. (b -> c) -> (a -> b) -> a -> c
. SimplEnv -> CoreBndr -> SimplSR
substId SimplEnv
env) [CoreBndr]
[XTickishId pass]
ids) Module
modl
    | Bool
otherwise = GenTickish pass
tickish

  -- Push type application and coercion inside a tick
  splitCont :: SimplCont -> (SimplCont, SimplCont)
  splitCont :: SimplCont -> (SimplCont, SimplCont)
splitCont cont :: SimplCont
cont@(ApplyToTy { sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
tail }) = (SimplCont
cont { sc_cont = inc }, SimplCont
outc)
    where (SimplCont
inc,SimplCont
outc) = SimplCont -> (SimplCont, SimplCont)
splitCont SimplCont
tail
  splitCont cont :: SimplCont
cont@(CastIt { sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
tail }) = (SimplCont
cont { sc_cont = inc }, SimplCont
outc)
    where (SimplCont
inc,SimplCont
outc) = SimplCont -> (SimplCont, SimplCont)
splitCont SimplCont
tail
  splitCont SimplCont
other = (Kind -> SimplCont
mkBoringStop (SimplCont -> Kind
contHoleType SimplCont
other), SimplCont
other)

  getDoneId :: SimplSR -> Maybe CoreBndr
getDoneId (DoneId CoreBndr
id)  = CoreBndr -> Maybe CoreBndr
forall a. a -> Maybe a
Just CoreBndr
id
  getDoneId (DoneEx (Var CoreBndr
id) JoinPointHood
_) = CoreBndr -> Maybe CoreBndr
forall a. a -> Maybe a
Just CoreBndr
id
  getDoneId (DoneEx CoreExpr
e JoinPointHood
_) = CoreExpr -> Maybe CoreBndr
getIdFromTrivialExpr_maybe CoreExpr
e -- Note [substTickish] in GHC.Core.Subst
  getDoneId SimplSR
other = String -> SDoc -> Maybe CoreBndr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"getDoneId" (SimplSR -> SDoc
forall a. Outputable a => a -> SDoc
ppr SimplSR
other)

-- Note [case-of-scc-of-case]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~
-- It's pretty important to be able to transform case-of-case when
-- there's an SCC in the way.  For example, the following comes up
-- in nofib/real/compress/Encode.hs:
--
--        case scctick<code_string.r1>
--             case $wcode_string_r13s wild_XC w1_s137 w2_s138 l_aje
--             of _ { (# ww1_s13f, ww2_s13g, ww3_s13h #) ->
--             (ww1_s13f, ww2_s13g, ww3_s13h)
--             }
--        of _ { (ww_s12Y, ww1_s12Z, ww2_s130) ->
--        tick<code_string.f1>
--        (ww_s12Y,
--         ww1_s12Z,
--         PTTrees.PT
--           @ GHC.Types.Char @ GHC.Types.Int wild2_Xj ww2_s130 r_ajf)
--        }
--
-- We really want this case-of-case to fire, because then the 3-tuple
-- will go away (indeed, the CPR optimisation is relying on this
-- happening).  But the scctick is in the way - we need to push it
-- inside to expose the case-of-case.  So we perform this
-- transformation on the inner case:
--
--   scctick c (case e of { p1 -> e1; ...; pn -> en })
--    ==>
--   case (scctick c e) of { p1 -> scc c e1; ...; pn -> scc c en }
--
-- So we've moved a constant amount of work out of the scc to expose
-- the case.  We only do this when the continuation is interesting: in
-- for now, it has to be another Case (maybe generalise this later).

{-
************************************************************************
*                                                                      *
\subsection{The main rebuilder}
*                                                                      *
************************************************************************
-}

rebuild :: SimplEnv -> OutExpr -> SimplCont -> SimplM (SimplFloats, OutExpr)
-- At this point the substitution in the SimplEnv should be irrelevant;
-- only the in-scope set matters
rebuild :: SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env CoreExpr
expr SimplCont
cont
  = case SimplCont
cont of
      Stop {}          -> (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, CoreExpr
expr)
      TickIt CoreTickish
t SimplCont
cont    -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (CoreTickish -> CoreExpr -> CoreExpr
mkTick CoreTickish
t CoreExpr
expr) SimplCont
cont
      CastIt { sc_co :: SimplCont -> CoercionR
sc_co = CoercionR
co, sc_opt :: SimplCont -> Bool
sc_opt = Bool
opt, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont }
        -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (HasDebugCallStack => CoreExpr -> CoercionR -> CoreExpr
CoreExpr -> CoercionR -> CoreExpr
mkCast CoreExpr
expr CoercionR
co') SimplCont
cont
           -- NB: mkCast implements the (Coercion co |> g) optimisation
        where
          co' :: CoercionR
co' = SimplEnv -> CoercionR -> Bool -> CoercionR
optOutCoercion SimplEnv
env CoercionR
co Bool
opt

      Select { sc_bndr :: SimplCont -> CoreBndr
sc_bndr = CoreBndr
bndr, sc_alts :: SimplCont -> [Alt CoreBndr]
sc_alts = [Alt CoreBndr]
alts, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
se, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont }
        -> SimplEnv
-> CoreExpr
-> CoreBndr
-> [Alt CoreBndr]
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
rebuildCase (SimplEnv
se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env) CoreExpr
expr CoreBndr
bndr [Alt CoreBndr]
alts SimplCont
cont

      StrictArg { sc_fun :: SimplCont -> ArgInfo
sc_fun = ArgInfo
fun, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont, sc_fun_ty :: SimplCont -> Kind
sc_fun_ty = Kind
fun_ty }
        -> SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo -> CoreExpr -> Kind -> ArgInfo
addValArgTo ArgInfo
fun CoreExpr
expr Kind
fun_ty ) SimplCont
cont

      StrictBind { sc_bndr :: SimplCont -> CoreBndr
sc_bndr = CoreBndr
b, sc_body :: SimplCont -> CoreExpr
sc_body = CoreExpr
body, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
se
                 , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont, sc_from :: SimplCont -> FromWhat
sc_from = FromWhat
from_what }
        -> SimplEnv
-> FromWhat
-> CoreBndr
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
completeBindX (SimplEnv
se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env) FromWhat
from_what CoreBndr
b CoreExpr
expr CoreExpr
body SimplCont
cont

      ApplyToTy  { sc_arg_ty :: SimplCont -> Kind
sc_arg_ty = Kind
ty, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont}
        -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (CoreExpr -> CoreExpr -> CoreExpr
forall b. Expr b -> Expr b -> Expr b
App CoreExpr
expr (Kind -> CoreExpr
forall b. Kind -> Expr b
Type Kind
ty)) SimplCont
cont

      ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
se, sc_dup :: SimplCont -> DupFlag
sc_dup = DupFlag
dup_flag
                 , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont, sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
fun_ty }
        -- See Note [Avoid redundant simplification]
        -> do { (_, _, arg') <- SimplEnv
-> DupFlag
-> Kind
-> Maybe ArgInfo
-> SimplEnv
-> CoreExpr
-> SimplM (DupFlag, SimplEnv, CoreExpr)
simplLazyArg SimplEnv
env DupFlag
dup_flag Kind
fun_ty Maybe ArgInfo
forall a. Maybe a
Nothing SimplEnv
se CoreExpr
arg
              ; rebuild env (App expr arg') cont }

completeBindX :: SimplEnv
              -> FromWhat
              -> InId -> OutExpr   -- Non-recursively bind this Id to this (simplified) expression
                                   -- (the let-can-float invariant may not be satisfied)
              -> InExpr            -- In this body
              -> SimplCont         -- Consumed by this continuation
              -> SimplM (SimplFloats, OutExpr)
completeBindX :: SimplEnv
-> FromWhat
-> CoreBndr
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
completeBindX SimplEnv
env FromWhat
from_what CoreBndr
bndr CoreExpr
rhs CoreExpr
body SimplCont
cont
  | FromBeta Levity
arg_levity <- FromWhat
from_what
  , Levity -> CoreExpr -> Bool
needsCaseBindingL Levity
arg_levity CoreExpr
rhs -- Enforcing the let-can-float-invariant
  = do { (env1, bndr1)   <- SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplNonRecBndr SimplEnv
env CoreBndr
bndr  -- Lambda binders don't have rules
       ; (floats, expr') <- simplNonRecBody env1 from_what body cont
       -- Do not float floats past the Case binder below
       ; let expr'' = SimplFloats -> CoreExpr -> CoreExpr
wrapFloats SimplFloats
floats CoreExpr
expr'
             case_expr = CoreExpr -> CoreBndr -> Kind -> [Alt CoreBndr] -> CoreExpr
forall b. Expr b -> b -> Kind -> [Alt b] -> Expr b
Case CoreExpr
rhs CoreBndr
bndr1 (SimplCont -> Kind
contResultType SimplCont
cont) [AltCon -> [CoreBndr] -> CoreExpr -> Alt CoreBndr
forall b. AltCon -> [b] -> Expr b -> Alt b
Alt AltCon
DEFAULT [] CoreExpr
expr'']
       ; return (emptyFloats env, case_expr) }

  | Bool
otherwise -- Make a let-binding
  = do  { (env1, bndr1) <- SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplNonRecBndr SimplEnv
env CoreBndr
bndr
        ; (env2, bndr2) <- addBndrRules env1 bndr bndr1 (BC_Let NotTopLevel NonRecursive)

        ; let is_strict = CoreBndr -> Bool
isStrictId CoreBndr
bndr2
              -- isStrictId: use simplified binder because the InId bndr might not have
              -- a fixed runtime representation, which isStrictId doesn't expect
              -- c.f. Note [Dark corner with representation polymorphism]

        ; (rhs_floats, rhs1) <- prepareBinding env NotTopLevel NonRecursive is_strict
                                               bndr2 (emptyFloats env) rhs
              -- NB: it makes a surprisingly big difference (5% in compiler allocation
              -- in T9630) to pass 'env' rather than 'env1'.  It's fine to pass 'env',
              -- because this is completeBindX, so bndr is not in scope in the RHS.

        ; let env3 = SimplEnv
env2 SimplEnv -> SimplFloats -> SimplEnv
`setInScopeFromF` SimplFloats
rhs_floats
        ; (bind_float, env4) <- completeBind (BC_Let NotTopLevel NonRecursive)
                                             (bndr,env) (bndr2, rhs1, env3)
              -- Must pass env1 to completeBind in case simplBinder had to clone,
              -- and extended the substitution with [bndr :-> new_bndr]

        -- Simplify the body
        ; (body_floats, body') <- simplNonRecBody env4 from_what body cont

        ; let all_floats = SimplFloats
rhs_floats SimplFloats -> SimplFloats -> SimplFloats
`addFloats` SimplFloats
bind_float SimplFloats -> SimplFloats -> SimplFloats
`addFloats` SimplFloats
body_floats
        ; return ( all_floats, body' ) }

{-
************************************************************************
*                                                                      *
\subsection{Lambdas}
*                                                                      *
************************************************************************
-}

{- Note [Optimising reflexivity]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's important (for compiler performance) to get rid of reflexivity as soon
as it appears.  See #11735, #14737, and #15019.

In particular, we want to behave well on

 *  e |> co1 |> co2
    where the two happen to cancel out entirely. That is quite common;
    e.g. a newtype wrapping and unwrapping cancel.


 * (f |> co) @t1 @t2 ... @tn x1 .. xm
   Here we will use pushCoTyArg and pushCoValArg successively, which
   build up SelCo stacks.  Silly to do that if co is reflexive.

However, we don't want to call isReflexiveCo too much, because it uses
type equality which is expensive on big types (#14737 comment:7).

A good compromise (determined experimentally) seems to be to call
isReflexiveCo
 * when composing casts, and
 * at the end

In investigating this I saw missed opportunities for on-the-fly
coercion shrinkage. See #15090.

Note [Avoid re-simplifying coercions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In some benchmarks (with deeply nested cases) we successively push
casts onto the SimplCont.  We don't want to call the coercion optimiser
on each successive composition -- that's at least quadratic.  So:

* The CastIt constructor in SimplCont has a `sc_opt :: Bool` flag to
  record whether the coercion optimiser has been applied to the coercion.

* In `simplCast`, when we see (Cast e co), we simplify `co` to get
  an OutCoercion, and built a CastIt with sc_opt=True.

  Actually not quite: if we are simplifying the result of inlining an
  unfolding (seInlineDepth > 0), then instead of /optimising/ it again,
  just /substitute/ which is cheaper.  See `simplCoercion`.

* In `addCoerce` (in `simplCast`) if we combine this new coercion with
  an existing once, we build a CastIt for (co1 ; co2) with sc_opt=False.

* When unpacking a CastIt, in `rebuildCall` and `rebuild`, we optimise
  the (presumably composed) coercion if sc_opt=False; this is done
  by `optOutCoercion`.

* When duplicating a continuation in `mkDupableContWithDmds`, before
  duplicating a CastIt, optimise the coercion. Otherwise we'll end up
  optimising it separately in the duplicate copies.
-}


optOutCoercion :: SimplEnv -> OutCoercion -> Bool -> OutCoercion
-- See Note [Avoid re-simplifying coercions]
optOutCoercion :: SimplEnv -> CoercionR -> Bool -> CoercionR
optOutCoercion SimplEnv
env CoercionR
co Bool
already_optimised
  | Bool
already_optimised = CoercionR
co  -- See Note [Avoid re-simplifying coercions]
  | Bool
otherwise         = OptCoercionOpts -> Subst -> CoercionR -> CoercionR
optCoercion OptCoercionOpts
opts Subst
empty_subst CoercionR
co
  where
    empty_subst :: Subst
empty_subst = InScopeSet -> Subst
mkEmptySubst (SimplEnv -> InScopeSet
seInScope SimplEnv
env)
    opts :: OptCoercionOpts
opts = SimplEnv -> OptCoercionOpts
seOptCoercionOpts SimplEnv
env

simplCast :: SimplEnv -> InExpr -> InCoercion -> SimplCont
          -> SimplM (SimplFloats, OutExpr)
simplCast :: SimplEnv
-> CoreExpr
-> CoercionR
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplCast SimplEnv
env CoreExpr
body CoercionR
co0 SimplCont
cont0
  = do  { co1   <- {-#SCC "simplCast-simplCoercion" #-} SimplEnv -> CoercionR -> SimplM CoercionR
simplCoercion SimplEnv
env CoercionR
co0
        ; cont1 <- {-#SCC "simplCast-addCoerce" #-}
                   if isReflCo co1
                   then return cont0  -- See Note [Optimising reflexivity]
                   else addCoerce co1 True cont0
                        -- True <=> co1 is optimised
        ; {-#SCC "simplCast-simplExprF" #-} simplExprF env body cont1 }
  where

        -- If the first parameter is MRefl, then simplifying revealed a
        -- reflexive coercion. Omit.
        addCoerceM :: MOutCoercion -> Bool -> SimplCont -> SimplM SimplCont
        addCoerceM :: MOutCoercion -> Bool -> SimplCont -> SimplM SimplCont
addCoerceM MOutCoercion
MRefl    Bool
_   SimplCont
cont = SimplCont -> SimplM SimplCont
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return SimplCont
cont
        addCoerceM (MCo CoercionR
co) Bool
opt SimplCont
cont = CoercionR -> Bool -> SimplCont -> SimplM SimplCont
addCoerce CoercionR
co Bool
opt SimplCont
cont

        addCoerce :: OutCoercion -> Bool -> SimplCont -> SimplM SimplCont
        addCoerce :: CoercionR -> Bool -> SimplCont -> SimplM SimplCont
addCoerce CoercionR
co1 Bool
_ (CastIt { sc_co :: SimplCont -> CoercionR
sc_co = CoercionR
co2, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })  -- See Note [Optimising reflexivity]
          = CoercionR -> Bool -> SimplCont -> SimplM SimplCont
addCoerce (CoercionR -> CoercionR -> CoercionR
mkTransCo CoercionR
co1 CoercionR
co2) Bool
False SimplCont
cont
                      -- False: (mkTransCo co1 co2) is not fully optimised
                      -- See Note [Avoid re-simplifying coercions]

        addCoerce CoercionR
co Bool
opt (ApplyToTy { sc_arg_ty :: SimplCont -> Kind
sc_arg_ty = Kind
arg_ty, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
tail })
          | Just (Kind
arg_ty', MOutCoercion
m_co') <- CoercionR -> Kind -> Maybe (Kind, MOutCoercion)
pushCoTyArg CoercionR
co Kind
arg_ty
          = {-#SCC "addCoerce-pushCoTyArg" #-}
            do { tail' <- MOutCoercion -> Bool -> SimplCont -> SimplM SimplCont
addCoerceM MOutCoercion
m_co' Bool
opt SimplCont
tail
               ; return (ApplyToTy { sc_arg_ty  = arg_ty'
                                   , sc_cont    = tail'
                                   , sc_hole_ty = coercionLKind co }) }
                                        -- NB!  As the cast goes past, the
                                        -- type of the hole changes (#16312)
        -- (f |> co) e   ===>   (f (e |> co1)) |> co2
        -- where   co :: (s1->s2) ~ (t1->t2)
        --         co1 :: t1 ~ s1
        --         co2 :: s2 ~ t2
        addCoerce CoercionR
co Bool
opt cont :: SimplCont
cont@(ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
arg_se
                                          , sc_dup :: SimplCont -> DupFlag
sc_dup = DupFlag
dup, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
tail
                                          , sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
fun_ty })
          | Bool -> Bool
not Bool
opt  -- pushCoValArg duplicates the coercion, so optimise first
          = CoercionR -> Bool -> SimplCont -> SimplM SimplCont
addCoerce (SimplEnv -> CoercionR -> Bool -> CoercionR
optOutCoercion SimplEnv
env CoercionR
co Bool
opt) Bool
True SimplCont
cont

          | Just (MOutCoercion
m_co1, MOutCoercion
m_co2) <- CoercionR -> Maybe (MOutCoercion, MOutCoercion)
pushCoValArg CoercionR
co
          , MOutCoercion -> Bool
fixed_rep MOutCoercion
m_co1
          = {-#SCC "addCoerce-pushCoValArg" #-}
            do { tail' <- MOutCoercion -> Bool -> SimplCont -> SimplM SimplCont
addCoerceM MOutCoercion
m_co2 Bool
opt SimplCont
tail
               ; case m_co1 of {
                   MOutCoercion
MRefl -> SimplCont -> SimplM SimplCont
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplCont
cont { sc_cont = tail'
                                         , sc_hole_ty = coercionLKind co }) ;
                      -- See Note [Avoiding simplifying repeatedly]

                   MCo CoercionR
co1 ->
            do { (dup', arg_se', arg') <- SimplEnv
-> DupFlag
-> Kind
-> Maybe ArgInfo
-> SimplEnv
-> CoreExpr
-> SimplM (DupFlag, SimplEnv, CoreExpr)
simplLazyArg SimplEnv
env DupFlag
dup Kind
fun_ty Maybe ArgInfo
forall a. Maybe a
Nothing SimplEnv
arg_se CoreExpr
arg
                    -- When we build the ApplyTo we can't mix the OutCoercion
                    -- 'co' with the InExpr 'arg', so we simplify
                    -- to make it all consistent.  It's a bit messy.
                    -- But it isn't a common case.
                    -- Example of use: #995
               ; return (ApplyToVal { sc_arg  = mkCast arg' co1
                                    , sc_env  = arg_se'
                                    , sc_dup  = dup'
                                    , sc_cont = tail'
                                    , sc_hole_ty = coercionLKind co }) } } }

        addCoerce CoercionR
co Bool
opt SimplCont
cont
          | CoercionR -> Bool
isReflCo CoercionR
co = SimplCont -> SimplM SimplCont
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return SimplCont
cont  -- Having this at the end makes a huge
                                       -- difference in T12227, for some reason
                                       -- See Note [Optimising reflexivity]
          | Bool
otherwise = SimplCont -> SimplM SimplCont
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (CastIt { sc_co :: CoercionR
sc_co = CoercionR
co, sc_opt :: Bool
sc_opt = Bool
opt, sc_cont :: SimplCont
sc_cont = SimplCont
cont })

        fixed_rep :: MCoercionR -> Bool
        fixed_rep :: MOutCoercion -> Bool
fixed_rep MOutCoercion
MRefl    = Bool
True
        fixed_rep (MCo CoercionR
co) = HasDebugCallStack => Kind -> Bool
Kind -> Bool
typeHasFixedRuntimeRep (Kind -> Bool) -> Kind -> Bool
forall a b. (a -> b) -> a -> b
$ CoercionR -> Kind
coercionRKind CoercionR
co
          -- Without this check, we can get an argument which does not
          -- have a fixed runtime representation.
          -- See Note [Representation polymorphism invariants] in GHC.Core
          -- test: typecheck/should_run/EtaExpandLevPoly

simplLazyArg :: SimplEnv -> DupFlag
             -> OutType                 -- ^ Type of the function applied to this arg
             -> Maybe ArgInfo           -- ^ Just <=> This arg `ai` occurs in an app
                                        --   `f a1 ... an` where we have ArgInfo on
                                        --   how `f` uses `ai`, affecting the Stop
                                        --   continuation passed to 'simplExprC'
             -> StaticEnv -> CoreExpr   -- ^ Expression with its static envt
             -> SimplM (DupFlag, StaticEnv, OutExpr)
simplLazyArg :: SimplEnv
-> DupFlag
-> Kind
-> Maybe ArgInfo
-> SimplEnv
-> CoreExpr
-> SimplM (DupFlag, SimplEnv, CoreExpr)
simplLazyArg SimplEnv
env DupFlag
dup_flag Kind
fun_ty Maybe ArgInfo
mb_arg_info SimplEnv
arg_env CoreExpr
arg
  | DupFlag -> Bool
isSimplified DupFlag
dup_flag
  = (DupFlag, SimplEnv, CoreExpr)
-> SimplM (DupFlag, SimplEnv, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (DupFlag
dup_flag, SimplEnv
arg_env, CoreExpr
arg)
  | Bool
otherwise
  = do { let arg_env' :: SimplEnv
arg_env' = SimplEnv
arg_env SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env
       ; let arg_ty :: Kind
arg_ty = HasDebugCallStack => Kind -> Kind
Kind -> Kind
funArgTy Kind
fun_ty
       ; let stop :: SimplCont
stop = case Maybe ArgInfo
mb_arg_info of
               Maybe ArgInfo
Nothing -> Kind -> SimplCont
mkBoringStop Kind
arg_ty
               Just ArgInfo
ai -> Kind -> ArgInfo -> SimplCont
mkLazyArgStop Kind
arg_ty ArgInfo
ai
       ; arg' <- SimplEnv -> CoreExpr -> SimplCont -> SimplM CoreExpr
simplExprC SimplEnv
arg_env' CoreExpr
arg SimplCont
stop
       ; return (Simplified, zapSubstEnv arg_env', arg') }
         -- Return a StaticEnv that includes the in-scope set from 'env',
         -- because arg' may well mention those variables (#20639)

{-
************************************************************************
*                                                                      *
\subsection{Lambdas}
*                                                                      *
************************************************************************
-}

simplNonRecBody :: SimplEnv -> FromWhat
                -> InExpr -> SimplCont
                -> SimplM (SimplFloats, OutExpr)
simplNonRecBody :: SimplEnv
-> FromWhat
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecBody SimplEnv
env FromWhat
from_what CoreExpr
body SimplCont
cont
  = case FromWhat
from_what of
      FromWhat
FromLet     -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
body SimplCont
cont
      FromBeta {} -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam   SimplEnv
env CoreExpr
body SimplCont
cont

simplLam :: SimplEnv -> InExpr -> SimplCont
         -> SimplM (SimplFloats, OutExpr)

simplLam :: SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam SimplEnv
env (Lam CoreBndr
bndr CoreExpr
body) SimplCont
cont = HasDebugCallStack =>
SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body SimplCont
cont
simplLam SimplEnv
env CoreExpr
expr            SimplCont
cont = SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env CoreExpr
expr SimplCont
cont

simpl_lam :: HasDebugCallStack
          => SimplEnv -> InBndr -> InExpr -> SimplCont
          -> SimplM (SimplFloats, OutExpr)

-- Type beta-reduction
simpl_lam :: HasDebugCallStack =>
SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body (ApplyToTy { sc_arg_ty :: SimplCont -> Kind
sc_arg_ty = Kind
arg_ty, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })
  = do { Tick -> SimplM ()
tick (CoreBndr -> Tick
BetaReduction CoreBndr
bndr)
       ; SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam (SimplEnv -> CoreBndr -> Kind -> SimplEnv
extendTvSubst SimplEnv
env CoreBndr
bndr Kind
arg_ty) CoreExpr
body SimplCont
cont }

-- Coercion beta-reduction
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body (ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = Coercion CoercionR
arg_co, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
arg_se
                                    , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })
  = Bool
-> SDoc
-> SimplM (SimplFloats, CoreExpr)
-> SimplM (SimplFloats, CoreExpr)
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (CoreBndr -> Bool
isCoVar CoreBndr
bndr) (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr) (SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$
    do { Tick -> SimplM ()
tick (CoreBndr -> Tick
BetaReduction CoreBndr
bndr)
       ; let arg_co' :: CoercionR
arg_co' = SimplEnv -> CoercionR -> CoercionR
substCo (SimplEnv
arg_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env) CoercionR
arg_co
       ; SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam (SimplEnv -> CoreBndr -> CoercionR -> SimplEnv
extendCvSubst SimplEnv
env CoreBndr
bndr CoercionR
arg_co') CoreExpr
body SimplCont
cont }

-- Value beta-reduction
-- This works for /coercion/ lambdas too
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body (ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
arg_se
                                    , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont, sc_dup :: SimplCont -> DupFlag
sc_dup = DupFlag
dup
                                    , sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
fun_ty})
  = do { Tick -> SimplM ()
tick (CoreBndr -> Tick
BetaReduction CoreBndr
bndr)
       ; let from_what :: FromWhat
from_what = Levity -> FromWhat
FromBeta Levity
arg_levity
             arg_levity :: Levity
arg_levity
               | Kind -> Bool
isForAllTy Kind
fun_ty = Bool -> SDoc -> Levity -> Levity
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr (CoreBndr -> Bool
isCoVar CoreBndr
bndr) (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
bndr) Levity
Unlifted
               | Bool
otherwise         = HasDebugCallStack => Kind -> Levity
Kind -> Levity
typeLevity (HasDebugCallStack => Kind -> Kind
Kind -> Kind
funArgTy Kind
fun_ty)
             -- Example:  (\(cv::a ~# b). blah) co
             -- The type of (\cv.blah) can be (forall cv. ty); see GHC.Core.Utils.mkLamType

             -- Using fun_ty: see Note [Dark corner with representation polymorphism]
             -- e.g  (\r \(a::TYPE r) \(x::a). blah) @LiftedRep @Int arg
             --      When we come to `x=arg` we must choose lazy/strict correctly
             --      It's wrong to err in either direction
             --      But fun_ty is an OutType, so is fully substituted

       ; if | DupFlag -> Bool
isSimplified DupFlag
dup  -- Don't re-simplify if we've simplified it once
                                -- Including don't preInlineUnconditionally
                                -- See Note [Avoiding simplifying repeatedly]
            -> SimplEnv
-> FromWhat
-> CoreBndr
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
completeBindX SimplEnv
env FromWhat
from_what CoreBndr
bndr CoreExpr
arg CoreExpr
body SimplCont
cont

            | Just SimplEnv
env' <- SimplEnv
-> TopLevelFlag
-> CoreBndr
-> CoreExpr
-> SimplEnv
-> Maybe SimplEnv
preInlineUnconditionally SimplEnv
env TopLevelFlag
NotTopLevel CoreBndr
bndr CoreExpr
arg SimplEnv
arg_se
            , Bool -> Bool
not (Levity -> CoreExpr -> Bool
needsCaseBindingL Levity
arg_levity CoreExpr
arg)
              -- Ok to test arg::InExpr in needsCaseBinding because
              -- exprOkForSpeculation is stable under simplification
            -> do { Tick -> SimplM ()
tick (CoreBndr -> Tick
PreInlineUnconditionally CoreBndr
bndr)
                  ; SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplLam SimplEnv
env' CoreExpr
body SimplCont
cont }

            | Bool
otherwise
            -> HasDebugCallStack =>
SimplEnv
-> FromWhat
-> CoreBndr
-> (CoreExpr, SimplEnv)
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
SimplEnv
-> FromWhat
-> CoreBndr
-> (CoreExpr, SimplEnv)
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecE SimplEnv
env FromWhat
from_what CoreBndr
bndr (CoreExpr
arg, SimplEnv
arg_se) CoreExpr
body SimplCont
cont }

-- Discard a non-counting tick on a lambda.  This may change the
-- cost attribution slightly (moving the allocation of the
-- lambda elsewhere), but we don't care: optimisation changes
-- cost attribution all the time.
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body (TickIt CoreTickish
tickish SimplCont
cont)
  | Bool -> Bool
not (CoreTickish -> Bool
forall (pass :: TickishPass). GenTickish pass -> Bool
tickishCounts CoreTickish
tickish)
  = HasDebugCallStack =>
SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
SimplEnv
-> CoreBndr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body SimplCont
cont

-- Not enough args, so there are real lambdas left to put in the result
simpl_lam SimplEnv
env CoreBndr
bndr CoreExpr
body SimplCont
cont
  = do  { let ([CoreBndr]
inner_bndrs, CoreExpr
inner_body) = CoreExpr -> ([CoreBndr], CoreExpr)
forall b. Expr b -> ([b], Expr b)
collectBinders CoreExpr
body
        ; (env', bndrs') <- SimplEnv -> [CoreBndr] -> SimplM (SimplEnv, [CoreBndr])
simplLamBndrs SimplEnv
env (CoreBndr
bndrCoreBndr -> [CoreBndr] -> [CoreBndr]
forall a. a -> [a] -> [a]
:[CoreBndr]
inner_bndrs)
        ; body'   <- simplExpr env' inner_body
        ; new_lam <- rebuildLam env' bndrs' body' cont
        ; rebuild env' new_lam cont }

-------------
simplLamBndr :: SimplEnv -> InBndr -> SimplM (SimplEnv, OutBndr)
-- Historically this had a special case for when a lambda-binder
-- could have a stable unfolding;
-- see Historical Note [Case binders and join points]
-- But now it is much simpler! We now only remove unfoldings.
-- See Note [Never put `OtherCon` unfoldings on lambda binders]
simplLamBndr :: SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplLamBndr SimplEnv
env CoreBndr
bndr = SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplBinder SimplEnv
env (CoreBndr -> CoreBndr
zapIdUnfolding CoreBndr
bndr)

simplLamBndrs :: SimplEnv -> [InBndr] -> SimplM (SimplEnv, [OutBndr])
simplLamBndrs :: SimplEnv -> [CoreBndr] -> SimplM (SimplEnv, [CoreBndr])
simplLamBndrs SimplEnv
env [CoreBndr]
bndrs = (SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr))
-> SimplEnv -> [CoreBndr] -> SimplM (SimplEnv, [CoreBndr])
forall (m :: * -> *) (t :: * -> *) acc x y.
(Monad m, Traversable t) =>
(acc -> x -> m (acc, y)) -> acc -> t x -> m (acc, t y)
mapAccumLM SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplLamBndr SimplEnv
env [CoreBndr]
bndrs

------------------
simplNonRecE :: HasDebugCallStack
             => SimplEnv
             -> FromWhat
             -> InId               -- The binder, always an Id
                                   -- Never a join point
                                   -- The static env for its unfolding (if any) is the first parameter
             -> (InExpr, SimplEnv) -- Rhs of binding (or arg of lambda)
             -> InExpr             -- Body of the let/lambda
             -> SimplCont
             -> SimplM (SimplFloats, OutExpr)

-- simplNonRecE is used for
--  * from=FromLet:  a non-top-level non-recursive non-join-point let-expression
--  * from=FromBeta: a binding arising from a beta reduction
--
-- simplNonRecE env b (rhs, rhs_se) body k
--   = let env in
--     cont< let b = rhs_se(rhs) in body >
--
-- It deals with strict bindings, via the StrictBind continuation,
-- which may abort the whole process.
--
-- from_what=FromLet => the RHS satisfies the let-can-float invariant
-- Otherwise it may or may not satisfy it.

simplNonRecE :: HasDebugCallStack =>
SimplEnv
-> FromWhat
-> CoreBndr
-> (CoreExpr, SimplEnv)
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecE SimplEnv
env FromWhat
from_what CoreBndr
bndr (CoreExpr
rhs, SimplEnv
rhs_se) CoreExpr
body SimplCont
cont
  | Bool -> Bool -> Bool
forall a. HasCallStack => Bool -> a -> a
assert (CoreBndr -> Bool
isId CoreBndr
bndr Bool -> Bool -> Bool
&& Bool -> Bool
not (CoreBndr -> Bool
isJoinId CoreBndr
bndr) ) (Bool -> Bool) -> Bool -> Bool
forall a b. (a -> b) -> a -> b
$
    Bool
is_strict_bind
  = -- Evaluate RHS strictly
    SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF (SimplEnv
rhs_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env) CoreExpr
rhs
               (StrictBind { sc_bndr :: CoreBndr
sc_bndr = CoreBndr
bndr, sc_body :: CoreExpr
sc_body = CoreExpr
body, sc_from :: FromWhat
sc_from = FromWhat
from_what
                           , sc_env :: SimplEnv
sc_env = SimplEnv
env, sc_cont :: SimplCont
sc_cont = SimplCont
cont, sc_dup :: DupFlag
sc_dup = DupFlag
NoDup })

  | Bool
otherwise  -- Evaluate RHS lazily
  = do { (env1, bndr1)    <- SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplNonRecBndr SimplEnv
env CoreBndr
bndr
       ; (env2, bndr2)    <- addBndrRules env1 bndr bndr1 (BC_Let NotTopLevel NonRecursive)
       ; (floats1, env3)  <- simplLazyBind NotTopLevel NonRecursive
                                           (bndr,env) (bndr2,env2) (rhs,rhs_se)
       ; (floats2, expr') <- simplNonRecBody env3 from_what body cont
       ; return (floats1 `addFloats` floats2, expr') }

  where
    is_strict_bind :: Bool
is_strict_bind = case FromWhat
from_what of
       FromBeta Levity
Unlifted -> Bool
True
       -- If we are coming from a beta-reduction (FromBeta) we must
       -- establish the let-can-float invariant, so go via StrictBind
       -- If not, the invariant holds already, and it's optional.

       -- (FromBeta Lifted) or FromLet: look at the demand info
       FromWhat
_ -> SimplEnv -> Bool
seCaseCase SimplEnv
env Bool -> Bool -> Bool
&& Demand -> Bool
isStrUsedDmd (CoreBndr -> Demand
idDemandInfo CoreBndr
bndr)


------------------
simplRecE :: SimplEnv
          -> [(InId, InExpr)]
          -> InExpr
          -> SimplCont
          -> SimplM (SimplFloats, OutExpr)

-- simplRecE is used for
--  * non-top-level recursive lets in expressions
-- Precondition: not a join-point binding
simplRecE :: SimplEnv
-> [(CoreBndr, CoreExpr)]
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplRecE SimplEnv
env [(CoreBndr, CoreExpr)]
pairs CoreExpr
body SimplCont
cont
  = do  { let bndrs :: [CoreBndr]
bndrs = ((CoreBndr, CoreExpr) -> CoreBndr)
-> [(CoreBndr, CoreExpr)] -> [CoreBndr]
forall a b. (a -> b) -> [a] -> [b]
map (CoreBndr, CoreExpr) -> CoreBndr
forall a b. (a, b) -> a
fst [(CoreBndr, CoreExpr)]
pairs
        ; Bool -> SimplM ()
forall (m :: * -> *). (HasCallStack, Applicative m) => Bool -> m ()
massert ((CoreBndr -> Bool) -> [CoreBndr] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Bool -> Bool
not (Bool -> Bool) -> (CoreBndr -> Bool) -> CoreBndr -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. CoreBndr -> Bool
isJoinId) [CoreBndr]
bndrs)
        ; env1 <- SimplEnv -> [CoreBndr] -> SimplM SimplEnv
simplRecBndrs SimplEnv
env [CoreBndr]
bndrs
                -- NB: bndrs' don't have unfoldings or rules
                -- We add them as we go down
        ; (floats1, env2)  <- simplRecBind env1 (BC_Let NotTopLevel Recursive) pairs
        ; (floats2, expr') <- simplExprF env2 body cont
        ; return (floats1 `addFloats` floats2, expr') }

{- Note [Dark corner with representation polymorphism]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In `simplNonRecE`, the call to `needsCaseBinding` or to `isStrictId` will fail
if the binder does not have a fixed runtime representation, e.g. if it is of kind (TYPE r).
So we are careful to call `isStrictId` on the OutId, not the InId, in case we have
     ((\(r::RuntimeRep) \(x::TYPE r). blah) Lifted arg)
That will lead to `simplNonRecE env (x::TYPE r) arg`, and we can't tell
if x is lifted or unlifted from that.

We only get such redexes from the compulsory inlining of a wired-in,
representation-polymorphic function like `rightSection` (see
GHC.Types.Id.Make).  Mind you, SimpleOpt should probably have inlined
such compulsory inlinings already, but belt and braces does no harm.

Plus, it turns out that GHC.Driver.Main.hscCompileCoreExpr calls the
Simplifier without first calling SimpleOpt, so anything involving
GHCi or TH and operator sections will fall over if we don't take
care here.

Note [Avoiding simplifying repeatedly]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One way in which we can get exponential behaviour is if we simplify a
big expression, and then re-simplify it -- and then this happens in a
deeply-nested way.  So we must be jolly careful about re-simplifying
an expression (#13379).

Example:
  f BIG, where f has a RULE
Then
 * We simplify BIG before trying the rule; but the rule does not fire
   (forcing this simplification is why we have the RULE in this example)
 * We inline f = \x. g x, in `simpl_lam`
 * So if `simpl_lam` did preInlineUnconditionally we get (g BIG)
 * Now if g has a RULE we'll simplify BIG again, and this whole thing can
   iterate.
 * However, if `f` did not have a RULE, so that BIG has /not/ already been
   simplified, we /want/ to do preInlineUnconditionally in simpl_lam.

So we go to some effort to avoid repeatedly simplifying the same thing:

* ApplyToVal has a (sc_dup :: DupFlag) field which records if the argument
  has been evaluated.

* simplArg checks this flag to avoid re-simplifying.

* simpl_lam has:
    - a case for (isSimplified dup), which goes via completeBindX, and
    - a case for an un-simplified argument, which tries preInlineUnconditionally

* We go to some efforts to avoid unnecessarily simplifying ApplyToVal,
  in at least two places
    - In simplCast/addCoerce, where we check for isReflCo
    - In rebuildCall we avoid simplifying arguments before we have to
      (see Note [Trying rewrite rules])

All that said /postInlineUnconditionally/ (called in `completeBind`) does
fire in the above (f BIG) situation.  See Note [Post-inline for single-use
things] in Simplify.Utils.  This certainly risks repeated simplification, but
in practice seems to be a small win.


************************************************************************
*                                                                      *
                     Join points
*                                                                      *
********************************************************************* -}

{- Note [Rules and unfolding for join points]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppose we have

   simplExpr (join j x = rhs                         ) cont
             (      {- RULE j (p:ps) = blah -}       )
             (      {- StableUnfolding j = blah -}   )
             (in blah                                )

Then we will push 'cont' into the rhs of 'j'.  But we should *also* push
'cont' into the RHS of
  * Any RULEs for j, e.g. generated by SpecConstr
  * Any stable unfolding for j, e.g. the result of an INLINE pragma

Simplifying rules and stable-unfoldings happens a bit after
simplifying the right-hand side, so we remember whether or not it
is a join point, and what 'cont' is, in a value of type MaybeJoinCont

#13900 was caused by forgetting to push 'cont' into the RHS
of a SpecConstr-generated RULE for a join point.
-}

simplNonRecJoinPoint :: SimplEnv -> InId -> InExpr
                     -> InExpr -> SimplCont
                     -> SimplM (SimplFloats, OutExpr)
simplNonRecJoinPoint :: SimplEnv
-> CoreBndr
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplNonRecJoinPoint SimplEnv
env CoreBndr
bndr CoreExpr
rhs CoreExpr
body SimplCont
cont
   = Bool
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a. HasCallStack => Bool -> a -> a
assert (CoreBndr -> Bool
isJoinId CoreBndr
bndr ) (SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$
     SimplEnv
-> SimplCont
-> (SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr)
wrapJoinCont SimplEnv
env SimplCont
cont ((SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
 -> SimplM (SimplFloats, CoreExpr))
-> (SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$ \ SimplEnv
env SimplCont
cont ->
     do { -- We push join_cont into the join RHS and the body;
          -- and wrap wrap_cont around the whole thing
        ; let mult :: Kind
mult   = SimplCont -> Kind
contHoleScaling SimplCont
cont
              res_ty :: Kind
res_ty = SimplCont -> Kind
contResultType SimplCont
cont
        ; (env1, bndr1)    <- SimplEnv -> CoreBndr -> Kind -> Kind -> SimplM (SimplEnv, CoreBndr)
simplNonRecJoinBndr SimplEnv
env CoreBndr
bndr Kind
mult Kind
res_ty
        ; (env2, bndr2)    <- addBndrRules env1 bndr bndr1 (BC_Join NonRecursive cont)
        ; (floats1, env3)  <- simplJoinBind NonRecursive cont (bndr,env) (bndr2,env2) (rhs,env)
        ; (floats2, body') <- simplExprF env3 body cont
        ; return (floats1 `addFloats` floats2, body') }


------------------
simplRecJoinPoint :: SimplEnv -> [(InId, InExpr)]
                  -> InExpr -> SimplCont
                  -> SimplM (SimplFloats, OutExpr)
simplRecJoinPoint :: SimplEnv
-> [(CoreBndr, CoreExpr)]
-> CoreExpr
-> SimplCont
-> SimplM (SimplFloats, CoreExpr)
simplRecJoinPoint SimplEnv
env [(CoreBndr, CoreExpr)]
pairs CoreExpr
body SimplCont
cont
  = SimplEnv
-> SimplCont
-> (SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr)
wrapJoinCont SimplEnv
env SimplCont
cont ((SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
 -> SimplM (SimplFloats, CoreExpr))
-> (SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr)
forall a b. (a -> b) -> a -> b
$ \ SimplEnv
env SimplCont
cont ->
    do { let bndrs :: [CoreBndr]
bndrs  = ((CoreBndr, CoreExpr) -> CoreBndr)
-> [(CoreBndr, CoreExpr)] -> [CoreBndr]
forall a b. (a -> b) -> [a] -> [b]
map (CoreBndr, CoreExpr) -> CoreBndr
forall a b. (a, b) -> a
fst [(CoreBndr, CoreExpr)]
pairs
             mult :: Kind
mult   = SimplCont -> Kind
contHoleScaling SimplCont
cont
             res_ty :: Kind
res_ty = SimplCont -> Kind
contResultType SimplCont
cont
       ; env1 <- SimplEnv -> [CoreBndr] -> Kind -> Kind -> SimplM SimplEnv
simplRecJoinBndrs SimplEnv
env [CoreBndr]
bndrs Kind
mult Kind
res_ty
               -- NB: bndrs' don't have unfoldings or rules
               -- We add them as we go down
       ; (floats1, env2)  <- simplRecBind env1 (BC_Join Recursive cont) pairs
       ; (floats2, body') <- simplExprF env2 body cont
       ; return (floats1 `addFloats` floats2, body') }

--------------------
wrapJoinCont :: SimplEnv -> SimplCont
             -> (SimplEnv -> SimplCont -> SimplM (SimplFloats, OutExpr))
             -> SimplM (SimplFloats, OutExpr)
-- Deal with making the continuation duplicable if necessary,
-- and with the no-case-of-case situation.
wrapJoinCont :: SimplEnv
-> SimplCont
-> (SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr))
-> SimplM (SimplFloats, CoreExpr)
wrapJoinCont SimplEnv
env SimplCont
cont SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr)
thing_inside
  | SimplCont -> Bool
contIsStop SimplCont
cont        -- Common case; no need for fancy footwork
  = SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr)
thing_inside SimplEnv
env SimplCont
cont

  | Bool -> Bool
not (SimplEnv -> Bool
seCaseCase SimplEnv
env)
    -- See Note [Join points with -fno-case-of-case]
  = do { (floats1, expr1) <- SimplEnv -> SimplCont -> SimplM (SimplFloats, CoreExpr)
thing_inside SimplEnv
env (Kind -> SimplCont
mkBoringStop (SimplCont -> Kind
contHoleType SimplCont
cont))
       ; let (floats2, expr2) = wrapJoinFloatsX floats1 expr1
       ; (floats3, expr3) <- rebuild (env `setInScopeFromF` floats2) expr2 cont
       ; return (floats2 `addFloats` floats3, expr3) }

  | Bool
otherwise
    -- Normal case; see Note [Join points and case-of-case]
  = do { (floats1, cont')  <- SimplEnv -> SimplCont -> SimplM (SimplFloats, SimplCont)
mkDupableCont SimplEnv
env SimplCont
cont
       ; (floats2, result) <- thing_inside (env `setInScopeFromF` floats1) cont'
       ; return (floats1 `addFloats` floats2, result) }


--------------------
trimJoinCont :: Id         -- Used only in error message
             -> JoinPointHood
             -> SimplCont -> SimplCont
-- Drop outer context from join point invocation (jump)
-- See Note [Join points and case-of-case]

trimJoinCont :: CoreBndr -> JoinPointHood -> SimplCont -> SimplCont
trimJoinCont CoreBndr
_ JoinPointHood
NotJoinPoint SimplCont
cont
  = SimplCont
cont -- Not a jump
trimJoinCont CoreBndr
var (JoinPoint Int
arity) SimplCont
cont
  = Int -> SimplCont -> SimplCont
trim Int
arity SimplCont
cont
  where
    trim :: Int -> SimplCont -> SimplCont
trim Int
0 cont :: SimplCont
cont@(Stop {})
      = SimplCont
cont
    trim Int
0 SimplCont
cont
      = Kind -> SimplCont
mkBoringStop (SimplCont -> Kind
contResultType SimplCont
cont)
    trim Int
n cont :: SimplCont
cont@(ApplyToVal { sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
k })
      = SimplCont
cont { sc_cont = trim (n-1) k }
    trim Int
n cont :: SimplCont
cont@(ApplyToTy { sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
k })
      = SimplCont
cont { sc_cont = trim (n-1) k } -- join arity counts types!
    trim Int
_ SimplCont
cont
      = String -> SDoc -> SimplCont
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"completeCall" (SDoc -> SimplCont) -> SDoc -> SimplCont
forall a b. (a -> b) -> a -> b
$ CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
var SDoc -> SDoc -> SDoc
forall doc. IsDoc doc => doc -> doc -> doc
$$ SimplCont -> SDoc
forall a. Outputable a => a -> SDoc
ppr SimplCont
cont


{- Note [Join points and case-of-case]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we perform the case-of-case transform (or otherwise push continuations
inward), we want to treat join points specially. Since they're always
tail-called and we want to maintain this invariant, we can do this (for any
evaluation context E):

  E[join j = e
    in case ... of
         A -> jump j 1
         B -> jump j 2
         C -> f 3]

    -->

  join j = E[e]
  in case ... of
       A -> jump j 1
       B -> jump j 2
       C -> E[f 3]

As is evident from the example, there are two components to this behavior:

  1. When entering the RHS of a join point, copy the context inside.
  2. When a join point is invoked, discard the outer context.

We need to be very careful here to remain consistent---neither part is
optional!

We need do make the continuation E duplicable (since we are duplicating it)
with mkDupableCont.


Note [Join points with -fno-case-of-case]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Supose case-of-case is switched off, and we are simplifying

    case (join j x = <j-rhs> in
          case y of
             A -> j 1
             B -> j 2
             C -> e) of <outer-alts>

Usually, we'd push the outer continuation (case . of <outer-alts>) into
both the RHS and the body of the join point j.  But since we aren't doing
case-of-case we may then end up with this totally bogus result

    join x = case <j-rhs> of <outer-alts> in
    case (case y of
             A -> j 1
             B -> j 2
             C -> e) of <outer-alts>

This would be OK in the language of the paper, but not in GHC: j is no longer
a join point.  We can only do the "push continuation into the RHS of the
join point j" if we also push the continuation right down to the /jumps/ to
j, so that it can evaporate there.  If we are doing case-of-case, we'll get to

    join x = case <j-rhs> of <outer-alts> in
    case y of
      A -> j 1
      B -> j 2
      C -> case e of <outer-alts>

which is great.

Bottom line: if case-of-case is off, we must stop pushing the continuation
inwards altogether at any join point.  Instead simplify the (join ... in ...)
with a Stop continuation, and wrap the original continuation around the
outside.  Surprisingly tricky!


************************************************************************
*                                                                      *
                     Variables
*                                                                      *
************************************************************************

Note [zapSubstEnv]
~~~~~~~~~~~~~~~~~~
When simplifying something that has already been simplified, be sure to
zap the SubstEnv.  This is VITAL.  Consider
     let x = e in
     let y = \z -> ...x... in
     \ x -> ...y...

We'll clone the inner \x, adding x->x' in the id_subst Then when we
inline y, we must *not* replace x by x' in the inlined copy!!

Note [Fast path for data constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For applications of a data constructor worker, the full glory of
rebuildCall is a waste of effort;
* They never inline, obviously
* They have no rewrite rules
* They are not strict (see Note [Data-con worker strictness]
  in GHC.Core.DataCon)
So it's fine to zoom straight to `rebuild` which just rebuilds the
call in a very straightforward way.

Some programs have a /lot/ of data constructors in the source program
(compiler/perf/T9961 is an example), so this fast path can be very
valuable.
-}

simplVar :: SimplEnv -> InVar -> SimplM OutExpr
-- Look up an InVar in the environment
simplVar :: SimplEnv -> CoreBndr -> SimplM CoreExpr
simplVar SimplEnv
env CoreBndr
var
  -- Why $! ? See Note [Bangs in the Simplifier]
  | CoreBndr -> Bool
isTyVar CoreBndr
var = CoreExpr -> SimplM CoreExpr
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> SimplM CoreExpr) -> CoreExpr -> SimplM CoreExpr
forall a b. (a -> b) -> a -> b
$! Kind -> CoreExpr
forall b. Kind -> Expr b
Type (Kind -> CoreExpr) -> Kind -> CoreExpr
forall a b. (a -> b) -> a -> b
$! (SimplEnv -> CoreBndr -> Kind
substTyVar SimplEnv
env CoreBndr
var)
  | CoreBndr -> Bool
isCoVar CoreBndr
var = CoreExpr -> SimplM CoreExpr
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> SimplM CoreExpr) -> CoreExpr -> SimplM CoreExpr
forall a b. (a -> b) -> a -> b
$! CoercionR -> CoreExpr
forall b. CoercionR -> Expr b
Coercion (CoercionR -> CoreExpr) -> CoercionR -> CoreExpr
forall a b. (a -> b) -> a -> b
$! (SimplEnv -> CoreBndr -> CoercionR
substCoVar SimplEnv
env CoreBndr
var)
  | Bool
otherwise
  = case SimplEnv -> CoreBndr -> SimplSR
substId SimplEnv
env CoreBndr
var of
        ContEx TvSubstEnv
tvs CvSubstEnv
cvs SimplIdSubst
ids CoreExpr
e -> let env' :: SimplEnv
env' = SimplEnv -> TvSubstEnv -> CvSubstEnv -> SimplIdSubst -> SimplEnv
setSubstEnv SimplEnv
env TvSubstEnv
tvs CvSubstEnv
cvs SimplIdSubst
ids
                                in SimplEnv -> CoreExpr -> SimplM CoreExpr
simplExpr SimplEnv
env' CoreExpr
e
        DoneId CoreBndr
var1          -> CoreExpr -> SimplM CoreExpr
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
var1)
        DoneEx CoreExpr
e JoinPointHood
_           -> CoreExpr -> SimplM CoreExpr
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
e

simplIdF :: SimplEnv -> InId -> SimplCont -> SimplM (SimplFloats, OutExpr)
simplIdF :: SimplEnv -> CoreBndr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplIdF SimplEnv
env CoreBndr
var SimplCont
cont
  | CoreBndr -> Bool
isDataConWorkId CoreBndr
var         -- See Note [Fast path for data constructors]
  = SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
var) SimplCont
cont
  | Bool
otherwise
  = case SimplEnv -> CoreBndr -> SimplSR
substId SimplEnv
env CoreBndr
var of
      ContEx TvSubstEnv
tvs CvSubstEnv
cvs SimplIdSubst
ids CoreExpr
e -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env' CoreExpr
e SimplCont
cont
        -- Don't trimJoinCont; haven't already simplified e,
        -- so the cont is not embodied in e
        where
          env' :: SimplEnv
env' = SimplEnv -> TvSubstEnv -> CvSubstEnv -> SimplIdSubst -> SimplEnv
setSubstEnv SimplEnv
env TvSubstEnv
tvs CvSubstEnv
cvs SimplIdSubst
ids

      DoneId CoreBndr
var1 ->
        do { rule_base <- SimplM RuleEnv
getSimplRules
           ; let cont' = CoreBndr -> JoinPointHood -> SimplCont -> SimplCont
trimJoinCont CoreBndr
var1 (CoreBndr -> JoinPointHood
idJoinPointHood CoreBndr
var1) SimplCont
cont
                 info  = SimplEnv -> RuleEnv -> CoreBndr -> SimplCont -> ArgInfo
mkArgInfo SimplEnv
env RuleEnv
rule_base CoreBndr
var1 SimplCont
cont'
           ; rebuildCall env info cont' }

      DoneEx CoreExpr
e JoinPointHood
mb_join -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env' CoreExpr
e SimplCont
cont'
        where
          cont' :: SimplCont
cont' = CoreBndr -> JoinPointHood -> SimplCont -> SimplCont
trimJoinCont CoreBndr
var JoinPointHood
mb_join SimplCont
cont
          env' :: SimplEnv
env'  = SimplEnv -> SimplEnv
zapSubstEnv SimplEnv
env  -- See Note [zapSubstEnv]

---------------------------------------------------------
--      Dealing with a call site

rebuildCall :: SimplEnv -> ArgInfo -> SimplCont
            -> SimplM (SimplFloats, OutExpr)

---------- Bottoming applications --------------
rebuildCall :: SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo { ai_fun :: ArgInfo -> CoreBndr
ai_fun = CoreBndr
fun, ai_args :: ArgInfo -> [ArgSpec]
ai_args = [ArgSpec]
rev_args, ai_dmds :: ArgInfo -> [Demand]
ai_dmds = [] }) SimplCont
cont
  -- When we run out of strictness args, it means
  -- that the call is definitely bottom; see GHC.Core.Opt.Simplify.Utils.mkArgInfo
  -- Then we want to discard the entire strict continuation.  E.g.
  --    * case (error "hello") of { ... }
  --    * (error "Hello") arg
  --    * f (error "Hello") where f is strict
  --    etc
  -- Then, especially in the first of these cases, we'd like to discard
  -- the continuation, leaving just the bottoming expression.  But the
  -- type might not be right, so we may have to add a coerce.
  | Bool -> Bool
not (SimplCont -> Bool
contIsTrivial SimplCont
cont)     -- Only do this if there is a non-trivial
                                 -- continuation to discard, else we do it
                                 -- again and again!
  = Kind -> ()
seqType Kind
cont_ty ()
-> SimplM (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a b. a -> b -> b
`seq`        -- See Note [Avoiding space leaks in OutType]
    (SimplFloats, CoreExpr) -> SimplM (SimplFloats, CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (SimplEnv -> SimplFloats
emptyFloats SimplEnv
env, CoreExpr -> Kind -> CoreExpr
castBottomExpr CoreExpr
res Kind
cont_ty)
  where
    res :: CoreExpr
res     = CoreBndr -> [ArgSpec] -> CoreExpr
argInfoExpr CoreBndr
fun [ArgSpec]
rev_args
    cont_ty :: Kind
cont_ty = SimplCont -> Kind
contResultType SimplCont
cont

---------- Try inlining, if ai_rewrite = TryInlining --------
-- In the TryInlining case we try inlining immediately, before simplifying
-- any (more) arguments. Why?  See Note [Rewrite rules and inlining].
--
-- If there are rewrite rules we'll skip this case until we have
-- simplified enough args to satisfy nr_wanted==0 in the TryRules case below
-- Then we'll try the rules, and if that fails, we'll do TryInlining
rebuildCall SimplEnv
env info :: ArgInfo
info@(ArgInfo { ai_fun :: ArgInfo -> CoreBndr
ai_fun = CoreBndr
fun, ai_args :: ArgInfo -> [ArgSpec]
ai_args = [ArgSpec]
rev_args
                              , ai_rewrite :: ArgInfo -> RewriteCall
ai_rewrite = RewriteCall
TryInlining }) SimplCont
cont
  = do { logger <- SimplM Logger
forall (m :: * -> *). HasLogger m => m Logger
getLogger
       ; let full_cont = SimplEnv -> [ArgSpec] -> SimplCont -> SimplCont
pushSimplifiedRevArgs SimplEnv
env [ArgSpec]
rev_args SimplCont
cont
       ; mb_inline <- tryInlining env logger fun full_cont
       ; case mb_inline of
            Just CoreExpr
expr -> do { Tick -> SimplM ()
checkedTick (CoreBndr -> Tick
UnfoldingDone CoreBndr
fun)
                            ; let env1 :: SimplEnv
env1 = SimplEnv -> SimplEnv
zapSubstEnv SimplEnv
env
                            ; SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env1 CoreExpr
expr SimplCont
full_cont }
            Maybe CoreExpr
Nothing -> SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo
info { ai_rewrite = TryNothing }) SimplCont
cont
       }

---------- Try rewrite RULES, if ai_rewrite = TryRules --------------
-- See Note [Rewrite rules and inlining]
-- See also Note [Trying rewrite rules]
rebuildCall SimplEnv
env info :: ArgInfo
info@(ArgInfo { ai_fun :: ArgInfo -> CoreBndr
ai_fun = CoreBndr
fun, ai_args :: ArgInfo -> [ArgSpec]
ai_args = [ArgSpec]
rev_args
                              , ai_rewrite :: ArgInfo -> RewriteCall
ai_rewrite = TryRules Int
nr_wanted [CoreRule]
rules }) SimplCont
cont
  | Int
nr_wanted Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0 Bool -> Bool -> Bool
|| Bool
no_more_args
  = -- We've accumulated a simplified call in <fun,rev_args>
    -- so try rewrite rules; see Note [RULES apply to simplified arguments]
    -- See also Note [Rules for recursive functions]
    do { mb_match <- SimplEnv
-> [CoreRule]
-> CoreBndr
-> [ArgSpec]
-> SimplCont
-> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))
tryRules SimplEnv
env [CoreRule]
rules CoreBndr
fun ([ArgSpec] -> [ArgSpec]
forall a. [a] -> [a]
reverse [ArgSpec]
rev_args) SimplCont
cont
       ; case mb_match of
             Just (SimplEnv
env', CoreExpr
rhs, SimplCont
cont') -> SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF SimplEnv
env' CoreExpr
rhs SimplCont
cont'
             Maybe (SimplEnv, CoreExpr, SimplCont)
Nothing -> SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo
info { ai_rewrite = TryInlining }) SimplCont
cont }
  where
    -- If we have run out of arguments, just try the rules; there might
    -- be some with lower arity.  Casts get in the way -- they aren't
    -- allowed on rule LHSs
    no_more_args :: Bool
no_more_args = case SimplCont
cont of
                      ApplyToTy  {} -> Bool
False
                      ApplyToVal {} -> Bool
False
                      SimplCont
_             -> Bool
True

---------- Simplify type applications and casts --------------
rebuildCall SimplEnv
env ArgInfo
info (CastIt { sc_co :: SimplCont -> CoercionR
sc_co = CoercionR
co, sc_opt :: SimplCont -> Bool
sc_opt = Bool
opt, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })
  = SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo -> CoercionR -> ArgInfo
addCastTo ArgInfo
info CoercionR
co') SimplCont
cont
  where
    co' :: CoercionR
co' = SimplEnv -> CoercionR -> Bool -> CoercionR
optOutCoercion SimplEnv
env CoercionR
co Bool
opt

rebuildCall SimplEnv
env ArgInfo
info (ApplyToTy { sc_arg_ty :: SimplCont -> Kind
sc_arg_ty = Kind
arg_ty, sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
hole_ty, sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })
  = SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo -> Kind -> Kind -> ArgInfo
addTyArgTo ArgInfo
info Kind
arg_ty Kind
hole_ty) SimplCont
cont

---------- The runRW# rule. Do this after absorbing all arguments ------
-- See Note [Simplification of runRW#] in GHC.CoreToSTG.Prep.
--
-- runRW# :: forall (r :: RuntimeRep) (o :: TYPE r). (State# RealWorld -> o) -> o
-- K[ runRW# rr ty body ]   -->   runRW rr' ty' (\s. K[ body s ])
rebuildCall SimplEnv
env (ArgInfo { ai_fun :: ArgInfo -> CoreBndr
ai_fun = CoreBndr
fun_id, ai_args :: ArgInfo -> [ArgSpec]
ai_args = [ArgSpec]
rev_args })
            (ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
arg_se
                        , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont, sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
fun_ty })
  | CoreBndr
fun_id CoreBndr -> Unique -> Bool
forall a. Uniquable a => a -> Unique -> Bool
`hasKey` Unique
runRWKey
  , [ TyArg { as_arg_ty :: ArgSpec -> Kind
as_arg_ty = Kind
hole_ty }, TyArg {} ] <- [ArgSpec]
rev_args
  -- Do this even if (contIsStop cont), or if seCaseCase is off.
  -- See Note [No eta-expansion in runRW#]
  = do { let arg_env :: SimplEnv
arg_env = SimplEnv
arg_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env

             overall_res_ty :: Kind
overall_res_ty  = SimplCont -> Kind
contResultType SimplCont
cont
             -- hole_ty is the type of the current runRW# application
             (SimplCont
outer_cont, Kind
new_runrw_res_ty, SimplCont
inner_cont)
                | SimplEnv -> Bool
seCaseCase SimplEnv
env = (Kind -> SimplCont
mkBoringStop Kind
overall_res_ty, Kind
overall_res_ty, SimplCont
cont)
                | Bool
otherwise      = (SimplCont
cont, Kind
hole_ty, Kind -> SimplCont
mkBoringStop Kind
hole_ty)
                -- Only when case-of-case is on. See GHC.Driver.Config.Core.Opt.Simplify
                --    Note [Case-of-case and full laziness]

       -- If the argument is a literal lambda already, take a short cut
       -- This isn't just efficiency:
       --    * If we don't do this we get a beta-redex every time, so the
       --      simplifier keeps doing more iterations.
       --    * Even more important: see Note [No eta-expansion in runRW#]
       ; arg' <- case CoreExpr
arg of
           Lam CoreBndr
s CoreExpr
body -> do { (env', s') <- SimplEnv -> CoreBndr -> SimplM (SimplEnv, CoreBndr)
simplBinder SimplEnv
arg_env CoreBndr
s
                            ; body' <- simplExprC env' body inner_cont
                            ; return (Lam s' body') }
                            -- Important: do not try to eta-expand this lambda
                            -- See Note [No eta-expansion in runRW#]

           CoreExpr
_ -> do { s' <- FastString -> Kind -> Kind -> SimplM CoreBndr
newId (String -> FastString
fsLit String
"s") Kind
ManyTy Kind
realWorldStatePrimTy
                   ; let (m,_,_) = splitFunTy fun_ty
                         env'  = SimplEnv
arg_env SimplEnv -> [CoreBndr] -> SimplEnv
`addNewInScopeIds` [CoreBndr
s']
                         cont' = ApplyToVal { sc_dup :: DupFlag
sc_dup = DupFlag
Simplified, sc_arg :: CoreExpr
sc_arg = CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
s'
                                            , sc_env :: SimplEnv
sc_env = SimplEnv
env', sc_cont :: SimplCont
sc_cont = SimplCont
inner_cont
                                            , sc_hole_ty :: Kind
sc_hole_ty = HasDebugCallStack => Kind -> Kind -> Kind -> Kind
Kind -> Kind -> Kind -> Kind
mkVisFunTy Kind
m Kind
realWorldStatePrimTy Kind
new_runrw_res_ty }
                                -- cont' applies to s', then K
                   ; body' <- simplExprC env' arg cont'
                   ; return (Lam s' body') }

       ; let rr'   = HasDebugCallStack => Kind -> Kind
Kind -> Kind
getRuntimeRep Kind
new_runrw_res_ty
             call' = CoreExpr -> [CoreExpr] -> CoreExpr
forall b. Expr b -> [Expr b] -> Expr b
mkApps (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
fun_id) [Kind -> CoreExpr
forall b. Kind -> Expr b
mkTyArg Kind
rr', Kind -> CoreExpr
forall b. Kind -> Expr b
mkTyArg Kind
new_runrw_res_ty, CoreExpr
arg']
       ; rebuild env call' outer_cont }

---------- Simplify value arguments --------------------
rebuildCall SimplEnv
env ArgInfo
fun_info
            (ApplyToVal { sc_arg :: SimplCont -> CoreExpr
sc_arg = CoreExpr
arg, sc_env :: SimplCont -> SimplEnv
sc_env = SimplEnv
arg_se
                        , sc_dup :: SimplCont -> DupFlag
sc_dup = DupFlag
dup_flag, sc_hole_ty :: SimplCont -> Kind
sc_hole_ty = Kind
fun_ty
                        , sc_cont :: SimplCont -> SimplCont
sc_cont = SimplCont
cont })
  -- Argument is already simplified
  | DupFlag -> Bool
isSimplified DupFlag
dup_flag     -- See Note [Avoid redundant simplification]
  = SimplEnv -> ArgInfo -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuildCall SimplEnv
env (ArgInfo -> CoreExpr -> Kind -> ArgInfo
addValArgTo ArgInfo
fun_info CoreExpr
arg Kind
fun_ty) SimplCont
cont

  -- Strict arguments
  | ArgInfo -> Bool
isStrictArgInfo ArgInfo
fun_info
  , SimplEnv -> Bool
seCaseCase SimplEnv
env    -- Only when case-of-case is on. See GHC.Driver.Config.Core.Opt.Simplify
                      --    Note [Case-of-case and full laziness]
  = -- pprTrace "Strict Arg" (ppr arg $$ ppr (seIdSubst env) $$ ppr (seInScope env)) $
    SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
simplExprF (SimplEnv
arg_se SimplEnv -> SimplEnv -> SimplEnv
`setInScopeFromE` SimplEnv
env) CoreExpr
arg
               (StrictArg { sc_fun :: ArgInfo
sc_fun = ArgInfo
fun_info, sc_fun_ty :: Kind
sc_fun_ty = Kind
fun_ty
                          , sc_dup :: DupFlag
sc_dup = DupFlag
Simplified
                          , sc_cont :: SimplCont
sc_cont = SimplCont
cont })
                -- Note [Shadowing in the Simplifier]

  -- Lazy arguments
  | Bool
otherwise
        -- DO NOT float anything outside, hence simplExprC
        -- There is no benefit (unlike in a let-binding), and we'd
        -- have to be very careful about bogus strictness through
        -- floating a demanded let.
  = do  { (_, _, arg') <- SimplEnv
-> DupFlag
-> Kind
-> Maybe ArgInfo
-> SimplEnv
-> CoreExpr
-> SimplM (DupFlag, SimplEnv, CoreExpr)
simplLazyArg SimplEnv
env DupFlag
dup_flag Kind
fun_ty (ArgInfo -> Maybe ArgInfo
forall a. a -> Maybe a
Just ArgInfo
fun_info) SimplEnv
arg_se CoreExpr
arg
        ; rebuildCall env (addValArgTo fun_info  arg' fun_ty) cont }

---------- No further useful info, revert to generic rebuild ------------
rebuildCall SimplEnv
env (ArgInfo { ai_fun :: ArgInfo -> CoreBndr
ai_fun = CoreBndr
fun, ai_args :: ArgInfo -> [ArgSpec]
ai_args = [ArgSpec]
rev_args }) SimplCont
cont
  = SimplEnv -> CoreExpr -> SimplCont -> SimplM (SimplFloats, CoreExpr)
rebuild SimplEnv
env (CoreBndr -> [ArgSpec] -> CoreExpr
argInfoExpr CoreBndr
fun [ArgSpec]
rev_args) SimplCont
cont

-----------------------------------
tryInlining :: SimplEnv -> Logger -> OutId -> SimplCont -> SimplM (Maybe OutExpr)
tryInlining :: SimplEnv
-> Logger -> CoreBndr -> SimplCont -> SimplM (Maybe CoreExpr)
tryInlining SimplEnv
env Logger
logger CoreBndr
var SimplCont
cont
  | Just CoreExpr
expr <- SimplEnv
-> Logger
-> CoreBndr
-> Bool
-> [ArgSummary]
-> CallCtxt
-> Maybe CoreExpr
callSiteInline SimplEnv
env Logger
logger CoreBndr
var Bool
lone_variable [ArgSummary]
arg_infos CallCtxt
interesting_cont
  = do { CoreExpr -> SimplCont -> SimplM ()
dump_inline CoreExpr
expr SimplCont
cont
       ; Maybe CoreExpr -> SimplM (Maybe CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> Maybe CoreExpr
forall a. a -> Maybe a
Just CoreExpr
expr) }

  | Bool
otherwise
  = Maybe CoreExpr -> SimplM (Maybe CoreExpr)
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe CoreExpr
forall a. Maybe a
Nothing

  where
    (Bool
lone_variable, [ArgSummary]
arg_infos, SimplCont
call_cont) = SimplCont -> (Bool, [ArgSummary], SimplCont)
contArgs SimplCont
cont
    interesting_cont :: CallCtxt
interesting_cont = SimplEnv -> SimplCont -> CallCtxt
interestingCallContext SimplEnv
env SimplCont
call_cont

    log_inlining :: SDoc -> SimplM ()
log_inlining SDoc
doc
      = IO () -> SimplM ()
forall a. IO a -> SimplM a
forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO (IO () -> SimplM ()) -> IO () -> SimplM ()
forall a b. (a -> b) -> a -> b
$ Logger
-> PprStyle -> DumpFlag -> String -> DumpFormat -> SDoc -> IO ()
logDumpFile Logger
logger (NamePprCtx -> PprStyle
mkDumpStyle NamePprCtx
alwaysQualify)
           DumpFlag
Opt_D_dump_inlinings
           String
"" DumpFormat
FormatText SDoc
doc

    dump_inline :: CoreExpr -> SimplCont -> SimplM ()
dump_inline CoreExpr
unfolding SimplCont
cont
      | Bool -> Bool
not (Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_dump_inlinings) = () -> SimplM ()
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
      | Bool -> Bool
not (Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_verbose_core2core)
      = Bool -> SimplM () -> SimplM ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Name -> Bool
isExternalName (CoreBndr -> Name
idName CoreBndr
var)) (SimplM () -> SimplM ()) -> SimplM () -> SimplM ()
forall a b. (a -> b) -> a -> b
$
            SDoc -> SimplM ()
log_inlining (SDoc -> SimplM ()) -> SDoc -> SimplM ()
forall a b. (a -> b) -> a -> b
$
                [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Inlining done:", Int -> SDoc -> SDoc
nest Int
4 (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
var)]
      | Bool
otherwise
      = SDoc -> SimplM ()
log_inlining (SDoc -> SimplM ()) -> SDoc -> SimplM ()
forall a b. (a -> b) -> a -> b
$
           [SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep [String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Inlining done: " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<> CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
var,
                Int -> SDoc -> SDoc
nest Int
4 ([SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat [String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Inlined fn: " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> Int -> SDoc -> SDoc
nest Int
2 (CoreExpr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreExpr
unfolding),
                              String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Cont:  " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SimplCont -> SDoc
forall a. Outputable a => a -> SDoc
ppr SimplCont
cont])]


{- Note [Trying rewrite rules]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider an application (f e1 e2 e3) where the e1,e2,e3 are not yet
simplified.  We want to simplify enough arguments to allow the rules
to apply, but it's more efficient to avoid simplifying e2,e3 if e1 alone
is sufficient.  Example: class ops
   (+) dNumInt e2 e3
If we rewrite ((+) dNumInt) to plusInt, we can take advantage of the
latter's strictness when simplifying e2, e3.  Moreover, suppose we have
  RULE  f Int = \x. x True

Then given (f Int e1) we rewrite to
   (\x. x True) e1
without simplifying e1.  Now we can inline x into its unique call site,
and absorb the True into it all in the same pass.  If we simplified
e1 first, we couldn't do that; see Note [Avoiding simplifying repeatedly].

So we try to apply rules if either
  (a) no_more_args: we've run out of argument that the rules can "see"
  (b) nr_wanted: none of the rules wants any more arguments


Note [RULES apply to simplified arguments]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's very desirable to try RULES once the arguments have been simplified, because
doing so ensures that rule cascades work in one pass.  Consider
   {-# RULES g (h x) = k x
             f (k x) = x #-}
   ...f (g (h x))...
Then we want to rewrite (g (h x)) to (k x) and only then try f's rules. If
we match f's rules against the un-simplified RHS, it won't match.  This
makes a particularly big difference when superclass selectors are involved:
        op ($p1 ($p2 (df d)))
We want all this to unravel in one sweep.

Note [Rewrite rules and inlining]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In general we try to arrange that inlining is disabled (via a pragma) if
a rewrite rule should apply, so that the rule has a decent chance to fire
before we inline the function.

But it turns out that (especially when type-class specialisation or
SpecConstr is involved) it is very helpful for the the rewrite rule to
"win" over inlining when both are active at once: see #21851, #22097.

The simplifier arranges to do this, as follows. In effect, the ai_rewrite
field of the ArgInfo record is the state of a little state-machine:

* mkArgInfo sets the ai_rewrite field to TryRules if there are any rewrite
  rules avaialable for that function.

* rebuildCall simplifies arguments until enough are simplified to match the
  rule with greatest arity.  See Note [RULES apply to simplified arguments]
  and the first field of `TryRules`.

  But no more! As soon as we have simplified enough arguments to satisfy the
  maximum-arity rules, we try the rules; see Note [Trying rewrite rules].

* Once we have tried rules (or immediately if there are no rules) set
  ai_rewrite to TryInlining, and the Simplifier will try to inline the
  function.  We want to try this immediately (before simplifying any (more)
  arguments). Why? Consider
      f BIG      where   f = \x{OneOcc}. ...x...
  If we inline `f` before simplifying `BIG` well use preInlineUnconditionally,
  and we'll simplify BIG once, at x's occurrence, rather than twice.

* GHC.Core.Opt.Simplify.Utils. mkRewriteCall: if there are no rules, and no
  unfolding, we can skip both TryRules and TryInlining, which saves work.

Note [Avoid redundant simplification]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Because RULES apply to simplified arguments, there's a danger of repeatedly
simplifying already-simplified arguments.  An important example is that of
        (>>=) d e1 e2
Here e1, e2 are simplified before the rule is applied, but don't really
participate in the rule firing. So we mark them as Simplified to avoid
re-simplifying them.

Note [Shadowing in the Simplifier]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This part of the simplifier may return an expression that has shadowing.
(See Note [Shadowing in Core] in GHC.Core.hs.) Consider
        f (...(\a -> e)...) (case y of (a,b) -> e')
where f is strict in its second arg
If we simplify the innermost one first we get (...(\a -> e)...)
Simplifying the second arg makes us float the case out, so we end up with
        case y of (a,b) -> f (...(\a -> e)...) e'
So the output does not have the no-shadowing invariant.  However, there is
no danger of getting name-capture, because when the first arg was simplified
we used an in-scope set that at least mentioned all the variables free in its
static environment, and that is enough.

We can't just do innermost first, or we'd end up with a dual problem:
        case x of (a,b) -> f e (...(\a -> e')...)

I spent hours trying to recover the no-shadowing invariant, but I just could
not think of an elegant way to do it.  The simplifier is already knee-deep in
continuations.  We have to keep the right in-scope set around; AND we have
to get the effect that finding (error "foo") in a strict arg position will
discard the entire application and replace it with (error "foo").  Getting
all this at once is TOO HARD!

See also Note [Shadowing in prepareAlts] in GHC.Core.Opt.Simplify.Utils.

Note [No eta-expansion in runRW#]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we see `runRW# (\s. blah)` we must not attempt to eta-expand that
lambda.  Why not?  Because
* `blah` can mention join points bound outside the runRW#
* eta-expansion uses arityType, and
* `arityType` cannot cope with free join Ids:

So the simplifier spots the literal lambda, and simplifies inside it.
It's a very special lambda, because it is the one the OccAnal spots and
allows join points bound /outside/ to be called /inside/.

See Note [No free join points in arityType] in GHC.Core.Opt.Arity

************************************************************************
*                                                                      *
                Rewrite rules
*                                                                      *
************************************************************************
-}

tryRules :: SimplEnv -> [CoreRule]
         -> Id
         -> [ArgSpec]   -- In /normal, forward/ order
         -> SimplCont
         -> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))

tryRules :: SimplEnv
-> [CoreRule]
-> CoreBndr
-> [ArgSpec]
-> SimplCont
-> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))
tryRules SimplEnv
env [CoreRule]
rules CoreBndr
fn [ArgSpec]
args SimplCont
call_cont
  | [CoreRule] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [CoreRule]
rules
  = Maybe (SimplEnv, CoreExpr, SimplCont)
-> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe (SimplEnv, CoreExpr, SimplCont)
forall a. Maybe a
Nothing

  | Just (CoreRule
rule, CoreExpr
rule_rhs) <- RuleOpts
-> InScopeEnv
-> (Activation -> Bool)
-> CoreBndr
-> [CoreExpr]
-> [CoreRule]
-> Maybe (CoreRule, CoreExpr)
lookupRule RuleOpts
ropts (SimplEnv -> InScopeEnv
getUnfoldingInRuleMatch SimplEnv
env)
                                        (SimplMode -> Activation -> Bool
activeRule (SimplEnv -> SimplMode
seMode SimplEnv
env)) CoreBndr
fn
                                        ([ArgSpec] -> [CoreExpr]
argInfoAppArgs [ArgSpec]
args) [CoreRule]
rules
  -- Fire a rule for the function
  = do { logger <- SimplM Logger
forall (m :: * -> *). HasLogger m => m Logger
getLogger
       ; checkedTick (RuleFired (ruleName rule))
       ; let cont' = SimplEnv -> [ArgSpec] -> SimplCont -> SimplCont
pushSimplifiedArgs SimplEnv
zapped_env
                                        (Int -> [ArgSpec] -> [ArgSpec]
forall a. Int -> [a] -> [a]
drop (CoreRule -> Int
ruleArity CoreRule
rule) [ArgSpec]
args)
                                        SimplCont
call_cont
                     -- (ruleArity rule) says how
                     -- many args the rule consumed

             occ_anald_rhs = CoreExpr -> CoreExpr
occurAnalyseExpr CoreExpr
rule_rhs
                 -- See Note [Occurrence-analyse after rule firing]
       ; dump logger rule rule_rhs
       ; return (Just (zapped_env, occ_anald_rhs, cont')) }
            -- The occ_anald_rhs and cont' are all Out things
            -- hence zapping the environment

  | Bool
otherwise  -- No rule fires
  = do { logger <- SimplM Logger
forall (m :: * -> *). HasLogger m => m Logger
getLogger
       ; nodump logger  -- This ensures that an empty file is written
       ; return Nothing }

  where
    ropts :: RuleOpts
ropts      = SimplEnv -> RuleOpts
seRuleOpts SimplEnv
env
    zapped_env :: SimplEnv
zapped_env = SimplEnv -> SimplEnv
zapSubstEnv SimplEnv
env  -- See Note [zapSubstEnv]

    printRuleModule :: CoreRule -> doc
printRuleModule CoreRule
rule
      = doc -> doc
forall doc. IsLine doc => doc -> doc
parens (doc -> (Module -> doc) -> Maybe Module -> doc
forall b a. b -> (a -> b) -> Maybe a -> b
maybe (String -> doc
forall doc. IsLine doc => String -> doc
text String
"BUILTIN")
                      (ModuleName -> doc
forall doc. IsLine doc => ModuleName -> doc
pprModuleName (ModuleName -> doc) -> (Module -> ModuleName) -> Module -> doc
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Module -> ModuleName
forall unit. GenModule unit -> ModuleName
moduleName)
                      (CoreRule -> Maybe Module
ruleModule CoreRule
rule))

    dump :: Logger -> CoreRule -> CoreExpr -> SimplM ()
dump Logger
logger CoreRule
rule CoreExpr
rule_rhs
      | Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_dump_rule_rewrites
      = DumpFlag -> String -> SDoc -> SimplM ()
forall {m :: * -> *}.
(HasLogger m, MonadIO m) =>
DumpFlag -> String -> SDoc -> m ()
log_rule DumpFlag
Opt_D_dump_rule_rewrites String
"Rule fired" (SDoc -> SimplM ()) -> SDoc -> SimplM ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
forall doc. IsDoc doc => [doc] -> doc
vcat
          [ String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Rule:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> FastString -> SDoc
forall doc. IsLine doc => FastString -> doc
ftext (CoreRule -> FastString
ruleName CoreRule
rule)
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Module:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+>  CoreRule -> SDoc
forall {doc}. IsLine doc => CoreRule -> doc
printRuleModule CoreRule
rule
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Before:" SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> Int -> SDoc -> SDoc
hang (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
fn) Int
2 ([SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep ((ArgSpec -> SDoc) -> [ArgSpec] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map ArgSpec -> SDoc
forall a. Outputable a => a -> SDoc
ppr [ArgSpec]
args))
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"After: " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SDoc -> Int -> SDoc -> SDoc
hang (CoreExpr -> SDoc
forall b. OutputableBndr b => Expr b -> SDoc
pprCoreExpr CoreExpr
rule_rhs) Int
2
                               ([SDoc] -> SDoc
forall doc. IsLine doc => [doc] -> doc
sep ([SDoc] -> SDoc) -> [SDoc] -> SDoc
forall a b. (a -> b) -> a -> b
$ (ArgSpec -> SDoc) -> [ArgSpec] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map ArgSpec -> SDoc
forall a. Outputable a => a -> SDoc
ppr ([ArgSpec] -> [SDoc]) -> [ArgSpec] -> [SDoc]
forall a b. (a -> b) -> a -> b
$ Int -> [ArgSpec] -> [ArgSpec]
forall a. Int -> [a] -> [a]
drop (CoreRule -> Int
ruleArity CoreRule
rule) [ArgSpec]
args)
          , String -> SDoc
forall doc. IsLine doc => String -> doc
text String
"Cont:  " SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> SimplCont -> SDoc
forall a. Outputable a => a -> SDoc
ppr SimplCont
call_cont ]

      | Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_dump_rule_firings
      = DumpFlag -> String -> SDoc -> SimplM ()
forall {m :: * -> *}.
(HasLogger m, MonadIO m) =>
DumpFlag -> String -> SDoc -> m ()
log_rule DumpFlag
Opt_D_dump_rule_firings String
"Rule fired:" (SDoc -> SimplM ()) -> SDoc -> SimplM ()
forall a b. (a -> b) -> a -> b
$
          FastString -> SDoc
forall doc. IsLine doc => FastString -> doc
ftext (CoreRule -> FastString
ruleName CoreRule
rule)
            SDoc -> SDoc -> SDoc
forall doc. IsLine doc => doc -> doc -> doc
<+> CoreRule -> SDoc
forall {doc}. IsLine doc => CoreRule -> doc
printRuleModule CoreRule
rule

      | Bool
otherwise
      = () -> SimplM ()
forall a. a -> SimplM a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    nodump :: Logger -> m ()
nodump Logger
logger
      | Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_dump_rule_rewrites
      = IO () -> m ()
forall a. IO a -> m a
forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO (IO () -> m ()) -> IO () -> m ()
forall a b. (a -> b) -> a -> b
$
          Logger -> DumpFlag -> IO ()
touchDumpFile Logger
logger DumpFlag
Opt_D_dump_rule_rewrites

      | Logger -> DumpFlag -> Bool
logHasDumpFlag Logger
logger DumpFlag
Opt_D_dump_rule_firings
      = IO () -> m ()
forall a. IO a -> m a
forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO (IO () -> m ()) -> IO () -> m ()
forall a b. (a -> b) -> a -> b
$
          Logger -> DumpFlag -> IO ()
touchDumpFile Logger
logger DumpFlag
Opt_D_dump_rule_firings

      | Bool
otherwise
      = () -> m ()
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return ()

    log_rule :: DumpFlag -> String -> SDoc -> m ()
log_rule DumpFlag
flag String
hdr SDoc
details
      = do
      { logger <- m Logger
forall (m :: * -> *). HasLogger m => m Logger
getLogger
      ; liftIO $ logDumpFile logger (mkDumpStyle alwaysQualify) flag "" FormatText
               $ sep [text hdr, nest 4 details]
      }

trySeqRules :: SimplEnv
            -> OutExpr -> InExpr   -- Scrutinee and RHS
            -> SimplCont
            -> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))
-- See Note [User-defined RULES for seq]
trySeqRules :: SimplEnv
-> CoreExpr
-> CoreExpr
-> SimplCont
-> SimplM (Maybe (SimplEnv, CoreExpr, SimplCont))
trySeqRules SimplEnv
in_env CoreExpr
scrut CoreExpr
rhs SimplCont
cont
  = do { rule_base <- SimplM RuleEnv
getSimplRules
       ; tryRules in_env (getRules rule_base seqId) seqId out_args rule_cont }
  where
    no_cast_scrut :: CoreExpr
no_cast_scrut = CoreExpr -> CoreExpr
forall {b}. Expr b -> Expr b
drop_casts CoreExpr
scrut
    scrut_ty :: Kind
scrut_ty  = HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
no_cast_scrut
    seq_id_ty :: Kind
seq_id_ty = CoreBndr -> Kind
idType CoreBndr
seqId                    -- forall r a (b::TYPE r). a -> b -> b
    res1_ty :: Kind
res1_ty   = HasDebugCallStack => Kind -> Kind -> Kind
Kind -> Kind -> Kind
piResultTy Kind
seq_id_ty Kind
rhs_rep    -- forall a (b::TYPE rhs_rep). a -> b -> b
    res2_ty :: Kind
res2_ty   = HasDebugCallStack => Kind -> Kind -> Kind
Kind -> Kind -> Kind
piResultTy Kind
res1_ty   Kind
scrut_ty   -- forall (b::TYPE rhs_rep). scrut_ty -> b -> b
    res3_ty :: Kind
res3_ty   = HasDebugCallStack => Kind -> Kind -> Kind
Kind -> Kind -> Kind
piResultTy Kind
res2_ty   Kind
rhs_ty     -- scrut_ty -> rhs_ty -> rhs_ty
    res4_ty :: Kind
res4_ty   = HasDebugCallStack => Kind -> Kind
Kind -> Kind
funResultTy Kind
res3_ty             -- rhs_ty -> rhs_ty
    rhs_ty :: Kind
rhs_ty    = HasDebugCallStack => SimplEnv -> Kind -> Kind
SimplEnv -> Kind -> Kind
substTy SimplEnv
in_env (HasDebugCallStack => CoreExpr -> Kind
CoreExpr -> Kind
exprType CoreExpr
rhs)
    rhs_rep :: Kind
rhs_rep   = HasDebugCallStack => Kind -> Kind
Kind -> Kind
getRuntimeRep Kind
rhs_ty
    out_args :: [ArgSpec]
out_args  = [ TyArg { as_arg_ty :: Kind
as_arg_ty  = Kind
rhs_rep
                        , as_hole_ty :: Kind
as_hole_ty = Kind
seq_id_ty }
                , TyArg { as_arg_ty :: Kind
as_arg_ty  = Kind
scrut_ty
                        , as_hole_ty :: Kind
as_hole_ty = Kind
res1_ty }
                , TyArg { as_arg_ty :: Kind
as_arg_ty  = Kind
rhs_ty
                        , as_hole_ty :: Kind
as_hole_ty = Kind
res2_ty }
                , ValArg { as_arg :: CoreExpr
as_arg = CoreExpr
no_cast_scrut
                         , as_dmd :: Demand
as_dmd = Demand
seqDmd
                         , as_hole_ty :: Kind
as_hole_ty = Kind
res3_ty } ]
    rule_cont :: SimplCont
rule_cont = ApplyToVal { sc_dup :: DupFlag
sc_dup = DupFlag
NoDup, sc_arg :: CoreExpr
sc_arg = CoreExpr
rhs
                           , sc_env :: SimplEnv
sc_env = SimplEnv
in_env, sc_cont :: SimplCont
sc_cont = SimplCont
cont
                           , sc_hole_ty :: Kind
sc_hole_ty = Kind
res4_ty }

    -- Lazily evaluated, so we don't do most of this

    drop_casts :: Expr b -> Expr b