{-
(c) The University of Glasgow 2006
(c) The AQUA Project, Glasgow University, 1996-1998


This module contains "tidying" code for *nested* expressions, bindings, rules.
The code for *top-level* bindings is in GHC.Iface.Tidy.
-}

{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -Wno-incomplete-record-updates #-}
module GHC.Core.Tidy (
        tidyExpr, tidyRules, tidyUnfolding
    ) where

#include "HsVersions.h"

import GHC.Prelude

import GHC.Core
import GHC.Core.Seq ( seqUnfolding )
import GHC.Types.Id
import GHC.Types.Id.Info
import GHC.Types.Demand ( zapDmdEnvSig )
import GHC.Core.Type     ( tidyType, tidyVarBndr )
import GHC.Core.Coercion ( tidyCo )
import GHC.Types.Var
import GHC.Types.Var.Env
import GHC.Types.Unique (getUnique)
import GHC.Types.Unique.FM
import GHC.Types.Name hiding (tidyNameOcc)
import GHC.Types.SrcLoc
import GHC.Types.Tickish
import GHC.Data.Maybe
import Data.List (mapAccumL)

{-
************************************************************************
*                                                                      *
\subsection{Tidying expressions, rules}
*                                                                      *
************************************************************************
-}

tidyBind :: TidyEnv
         -> CoreBind
         ->  (TidyEnv, CoreBind)

tidyBind :: TidyEnv -> CoreBind -> (TidyEnv, CoreBind)
tidyBind TidyEnv
env (NonRec Id
bndr Expr Id
rhs)
  = TidyEnv -> TidyEnv -> Id -> (TidyEnv, Id)
tidyLetBndr TidyEnv
env TidyEnv
env Id
bndr forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', Id
bndr') ->
    (TidyEnv
env', forall b. b -> Expr b -> Bind b
NonRec Id
bndr' (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env' Expr Id
rhs))

tidyBind TidyEnv
env (Rec [(Id, Expr Id)]
prs)
  = let
       ([Id]
bndrs, [Expr Id]
rhss)  = forall a b. [(a, b)] -> ([a], [b])
unzip [(Id, Expr Id)]
prs
       (TidyEnv
env', [Id]
bndrs') = forall (t :: * -> *) s a b.
Traversable t =>
(s -> a -> (s, b)) -> s -> t a -> (s, t b)
mapAccumL (TidyEnv -> TidyEnv -> Id -> (TidyEnv, Id)
tidyLetBndr TidyEnv
env') TidyEnv
env [Id]
bndrs
    in
    forall a b. (a -> b) -> [a] -> [b]
map (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env') [Expr Id]
rhss forall a b. a -> (a -> b) -> b
=: \ [Expr Id]
rhss' ->
    (TidyEnv
env', forall b. [(b, Expr b)] -> Bind b
Rec (forall a b. [a] -> [b] -> [(a, b)]
zip [Id]
bndrs' [Expr Id]
rhss'))


------------  Expressions  --------------
tidyExpr :: TidyEnv -> CoreExpr -> CoreExpr
tidyExpr :: TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env (Var Id
v)       = forall b. Id -> Expr b
Var (TidyEnv -> Id -> Id
tidyVarOcc TidyEnv
env Id
v)
tidyExpr TidyEnv
env (Type Type
ty)     = forall b. Type -> Expr b
Type (TidyEnv -> Type -> Type
tidyType TidyEnv
env Type
ty)
tidyExpr TidyEnv
env (Coercion Coercion
co) = forall b. Coercion -> Expr b
Coercion (TidyEnv -> Coercion -> Coercion
tidyCo TidyEnv
env Coercion
co)
tidyExpr TidyEnv
_   (Lit Literal
lit)     = forall b. Literal -> Expr b
Lit Literal
lit
tidyExpr TidyEnv
env (App Expr Id
f Expr Id
a)     = forall b. Expr b -> Expr b -> Expr b
App (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env Expr Id
f) (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env Expr Id
a)
tidyExpr TidyEnv
env (Tick CoreTickish
t Expr Id
e)    = forall b. CoreTickish -> Expr b -> Expr b
Tick (TidyEnv -> CoreTickish -> CoreTickish
tidyTickish TidyEnv
env CoreTickish
t) (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env Expr Id
e)
tidyExpr TidyEnv
env (Cast Expr Id
e Coercion
co)   = forall b. Expr b -> Coercion -> Expr b
Cast (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env Expr Id
e) (TidyEnv -> Coercion -> Coercion
tidyCo TidyEnv
env Coercion
co)

tidyExpr TidyEnv
env (Let CoreBind
b Expr Id
e)
  = TidyEnv -> CoreBind -> (TidyEnv, CoreBind)
tidyBind TidyEnv
env CoreBind
b      forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', CoreBind
b') ->
    forall b. Bind b -> Expr b -> Expr b
Let CoreBind
b' (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env' Expr Id
e)

tidyExpr TidyEnv
env (Case Expr Id
e Id
b Type
ty [Alt Id]
alts)
  = TidyEnv -> Id -> (TidyEnv, Id)
tidyBndr TidyEnv
env Id
b  forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', Id
b) ->
    forall b. Expr b -> b -> Type -> [Alt b] -> Expr b
Case (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env Expr Id
e) Id
b (TidyEnv -> Type -> Type
tidyType TidyEnv
env Type
ty)
         (forall a b. (a -> b) -> [a] -> [b]
map (TidyEnv -> Alt Id -> Alt Id
tidyAlt TidyEnv
env') [Alt Id]
alts)

tidyExpr TidyEnv
env (Lam Id
b Expr Id
e)
  = TidyEnv -> Id -> (TidyEnv, Id)
tidyBndr TidyEnv
env Id
b      forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', Id
b) ->
    forall b. b -> Expr b -> Expr b
Lam Id
b (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env' Expr Id
e)

------------  Case alternatives  --------------
tidyAlt :: TidyEnv -> CoreAlt -> CoreAlt
tidyAlt :: TidyEnv -> Alt Id -> Alt Id
tidyAlt TidyEnv
env (Alt AltCon
con [Id]
vs Expr Id
rhs)
  = TidyEnv -> [Id] -> (TidyEnv, [Id])
tidyBndrs TidyEnv
env [Id]
vs    forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', [Id]
vs) ->
    (forall b. AltCon -> [b] -> Expr b -> Alt b
Alt AltCon
con [Id]
vs (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env' Expr Id
rhs))

------------  Tickish  --------------
tidyTickish :: TidyEnv -> CoreTickish -> CoreTickish
tidyTickish :: TidyEnv -> CoreTickish -> CoreTickish
tidyTickish TidyEnv
env (Breakpoint XBreakpoint 'TickishPassCore
ext Int
ix [XTickishId 'TickishPassCore]
ids)
  = forall (pass :: TickishPass).
XBreakpoint pass -> Int -> [XTickishId pass] -> GenTickish pass
Breakpoint XBreakpoint 'TickishPassCore
ext Int
ix (forall a b. (a -> b) -> [a] -> [b]
map (TidyEnv -> Id -> Id
tidyVarOcc TidyEnv
env) [XTickishId 'TickishPassCore]
ids)
tidyTickish TidyEnv
_   CoreTickish
other_tickish       = CoreTickish
other_tickish

------------  Rules  --------------
tidyRules :: TidyEnv -> [CoreRule] -> [CoreRule]
tidyRules :: TidyEnv -> [CoreRule] -> [CoreRule]
tidyRules TidyEnv
_   [] = []
tidyRules TidyEnv
env (CoreRule
rule : [CoreRule]
rules)
  = TidyEnv -> CoreRule -> CoreRule
tidyRule TidyEnv
env CoreRule
rule           forall a b. a -> (a -> b) -> b
=: \ CoreRule
rule ->
    TidyEnv -> [CoreRule] -> [CoreRule]
tidyRules TidyEnv
env [CoreRule]
rules         forall a b. a -> (a -> b) -> b
=: \ [CoreRule]
rules ->
    (CoreRule
rule forall a. a -> [a] -> [a]
: [CoreRule]
rules)

tidyRule :: TidyEnv -> CoreRule -> CoreRule
tidyRule :: TidyEnv -> CoreRule -> CoreRule
tidyRule TidyEnv
_   rule :: CoreRule
rule@(BuiltinRule {}) = CoreRule
rule
tidyRule TidyEnv
env rule :: CoreRule
rule@(Rule { ru_bndrs :: CoreRule -> [Id]
ru_bndrs = [Id]
bndrs, ru_args :: CoreRule -> [Expr Id]
ru_args = [Expr Id]
args, ru_rhs :: CoreRule -> Expr Id
ru_rhs = Expr Id
rhs,
                          ru_fn :: CoreRule -> Name
ru_fn = Name
fn, ru_rough :: CoreRule -> [Maybe Name]
ru_rough = [Maybe Name]
mb_ns })
  = TidyEnv -> [Id] -> (TidyEnv, [Id])
tidyBndrs TidyEnv
env [Id]
bndrs         forall a b. a -> (a -> b) -> b
=: \ (TidyEnv
env', [Id]
bndrs) ->
    forall a b. (a -> b) -> [a] -> [b]
map (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env') [Expr Id]
args    forall a b. a -> (a -> b) -> b
=: \ [Expr Id]
args ->
    CoreRule
rule { ru_bndrs :: [Id]
ru_bndrs = [Id]
bndrs, ru_args :: [Expr Id]
ru_args = [Expr Id]
args,
           ru_rhs :: Expr Id
ru_rhs   = TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
env' Expr Id
rhs,
           ru_fn :: Name
ru_fn    = TidyEnv -> Name -> Name
tidyNameOcc TidyEnv
env Name
fn,
           ru_rough :: [Maybe Name]
ru_rough = forall a b. (a -> b) -> [a] -> [b]
map (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (TidyEnv -> Name -> Name
tidyNameOcc TidyEnv
env')) [Maybe Name]
mb_ns }

{-
************************************************************************
*                                                                      *
\subsection{Tidying non-top-level binders}
*                                                                      *
************************************************************************
-}

tidyNameOcc :: TidyEnv -> Name -> Name
-- In rules and instances, we have Names, and we must tidy them too
-- Fortunately, we can lookup in the VarEnv with a name
tidyNameOcc :: TidyEnv -> Name -> Name
tidyNameOcc (TidyOccEnv
_, VarEnv Id
var_env) Name
n = case forall key elt. UniqFM key elt -> Unique -> Maybe elt
lookupUFM_Directly VarEnv Id
var_env (forall a. Uniquable a => a -> Unique
getUnique Name
n) of
                                Maybe Id
Nothing -> Name
n
                                Just Id
v  -> Id -> Name
idName Id
v

tidyVarOcc :: TidyEnv -> Var -> Var
tidyVarOcc :: TidyEnv -> Id -> Id
tidyVarOcc (TidyOccEnv
_, VarEnv Id
var_env) Id
v = forall a. VarEnv a -> Id -> Maybe a
lookupVarEnv VarEnv Id
var_env Id
v forall a. Maybe a -> a -> a
`orElse` Id
v

-- tidyBndr is used for lambda and case binders
tidyBndr :: TidyEnv -> Var -> (TidyEnv, Var)
tidyBndr :: TidyEnv -> Id -> (TidyEnv, Id)
tidyBndr TidyEnv
env Id
var
  | Id -> Bool
isTyCoVar Id
var = TidyEnv -> Id -> (TidyEnv, Id)
tidyVarBndr TidyEnv
env Id
var
  | Bool
otherwise     = TidyEnv -> Id -> (TidyEnv, Id)
tidyIdBndr TidyEnv
env Id
var

tidyBndrs :: TidyEnv -> [Var] -> (TidyEnv, [Var])
tidyBndrs :: TidyEnv -> [Id] -> (TidyEnv, [Id])
tidyBndrs TidyEnv
env [Id]
vars = forall (t :: * -> *) s a b.
Traversable t =>
(s -> a -> (s, b)) -> s -> t a -> (s, t b)
mapAccumL TidyEnv -> Id -> (TidyEnv, Id)
tidyBndr TidyEnv
env [Id]
vars

-- Non-top-level variables, not covars
tidyIdBndr :: TidyEnv -> Id -> (TidyEnv, Id)
tidyIdBndr :: TidyEnv -> Id -> (TidyEnv, Id)
tidyIdBndr env :: TidyEnv
env@(TidyOccEnv
tidy_env, VarEnv Id
var_env) Id
id
  = -- Do this pattern match strictly, otherwise we end up holding on to
    -- stuff in the OccName.
    case TidyOccEnv -> OccName -> (TidyOccEnv, OccName)
tidyOccName TidyOccEnv
tidy_env (forall a. NamedThing a => a -> OccName
getOccName Id
id) of { (TidyOccEnv
tidy_env', OccName
occ') ->
    let
        -- Give the Id a fresh print-name, *and* rename its type
        -- The SrcLoc isn't important now,
        -- though we could extract it from the Id
        --
        ty' :: Type
ty'      = TidyEnv -> Type -> Type
tidyType TidyEnv
env (Id -> Type
idType Id
id)
        mult' :: Type
mult'    = TidyEnv -> Type -> Type
tidyType TidyEnv
env (Id -> Type
idMult Id
id)
        name' :: Name
name'    = Unique -> OccName -> SrcSpan -> Name
mkInternalName (Id -> Unique
idUnique Id
id) OccName
occ' SrcSpan
noSrcSpan
        id' :: Id
id'      = HasDebugCallStack => Name -> Type -> Type -> IdInfo -> Id
mkLocalIdWithInfo Name
name' Type
mult' Type
ty' IdInfo
new_info
        var_env' :: VarEnv Id
var_env' = forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv VarEnv Id
var_env Id
id Id
id'

        -- Note [Tidy IdInfo]
        new_info :: IdInfo
new_info = IdInfo
vanillaIdInfo IdInfo -> OccInfo -> IdInfo
`setOccInfo` IdInfo -> OccInfo
occInfo IdInfo
old_info
                                 IdInfo -> Unfolding -> IdInfo
`setUnfoldingInfo` Unfolding
new_unf
                                  -- see Note [Preserve OneShotInfo]
                                 IdInfo -> OneShotInfo -> IdInfo
`setOneShotInfo` IdInfo -> OneShotInfo
oneShotInfo IdInfo
old_info
        old_info :: IdInfo
old_info = HasDebugCallStack => Id -> IdInfo
idInfo Id
id
        old_unf :: Unfolding
old_unf  = IdInfo -> Unfolding
unfoldingInfo IdInfo
old_info
        new_unf :: Unfolding
new_unf  = Unfolding -> Unfolding
zapUnfolding Unfolding
old_unf  -- See Note [Preserve evaluatedness]
    in
    ((TidyOccEnv
tidy_env', VarEnv Id
var_env'), Id
id')
   }

tidyLetBndr :: TidyEnv         -- Knot-tied version for unfoldings
            -> TidyEnv         -- The one to extend
            -> Id -> (TidyEnv, Id)
-- Used for local (non-top-level) let(rec)s
-- Just like tidyIdBndr above, but with more IdInfo
tidyLetBndr :: TidyEnv -> TidyEnv -> Id -> (TidyEnv, Id)
tidyLetBndr TidyEnv
rec_tidy_env env :: TidyEnv
env@(TidyOccEnv
tidy_env, VarEnv Id
var_env) Id
id
  = case TidyOccEnv -> OccName -> (TidyOccEnv, OccName)
tidyOccName TidyOccEnv
tidy_env (forall a. NamedThing a => a -> OccName
getOccName Id
id) of { (TidyOccEnv
tidy_env', OccName
occ') ->
    let
        ty' :: Type
ty'      = TidyEnv -> Type -> Type
tidyType TidyEnv
env (Id -> Type
idType Id
id)
        mult' :: Type
mult'    = TidyEnv -> Type -> Type
tidyType TidyEnv
env (Id -> Type
idMult Id
id)
        name' :: Name
name'    = Unique -> OccName -> SrcSpan -> Name
mkInternalName (Id -> Unique
idUnique Id
id) OccName
occ' SrcSpan
noSrcSpan
        details :: IdDetails
details  = Id -> IdDetails
idDetails Id
id
        id' :: Id
id'      = IdDetails -> Name -> Type -> Type -> IdInfo -> Id
mkLocalVar IdDetails
details Name
name' Type
mult' Type
ty' IdInfo
new_info
        var_env' :: VarEnv Id
var_env' = forall a. VarEnv a -> Id -> a -> VarEnv a
extendVarEnv VarEnv Id
var_env Id
id Id
id'

        -- Note [Tidy IdInfo]
        -- We need to keep around any interesting strictness and
        -- demand info because later on we may need to use it when
        -- converting to A-normal form.
        -- eg.
        --      f (g x),  where f is strict in its argument, will be converted
        --      into  case (g x) of z -> f z  by CorePrep, but only if f still
        --      has its strictness info.
        --
        -- Similarly for the demand info - on a let binder, this tells
        -- CorePrep to turn the let into a case.
        -- But: Remove the usage demand here
        --      (See Note [Zapping DmdEnv after Demand Analyzer] in GHC.Core.Opt.WorkWrap)
        --
        -- Similarly arity info for eta expansion in CorePrep
        -- Don't attempt to recompute arity here; this is just tidying!
        -- Trying to do so led to #17294
        --
        -- Set inline-prag info so that we preserve it across
        -- separate compilation boundaries
        old_info :: IdInfo
old_info = HasDebugCallStack => Id -> IdInfo
idInfo Id
id
        new_info :: IdInfo
new_info = IdInfo
vanillaIdInfo
                    IdInfo -> OccInfo -> IdInfo
`setOccInfo`        IdInfo -> OccInfo
occInfo IdInfo
old_info
                    IdInfo -> Int -> IdInfo
`setArityInfo`      IdInfo -> Int
arityInfo IdInfo
old_info
                    IdInfo -> StrictSig -> IdInfo
`setStrictnessInfo` StrictSig -> StrictSig
zapDmdEnvSig (IdInfo -> StrictSig
strictnessInfo IdInfo
old_info)
                    IdInfo -> Demand -> IdInfo
`setDemandInfo`     IdInfo -> Demand
demandInfo IdInfo
old_info
                    IdInfo -> InlinePragma -> IdInfo
`setInlinePragInfo` IdInfo -> InlinePragma
inlinePragInfo IdInfo
old_info
                    IdInfo -> Unfolding -> IdInfo
`setUnfoldingInfo`  Unfolding
new_unf

        old_unf :: Unfolding
old_unf = IdInfo -> Unfolding
unfoldingInfo IdInfo
old_info
        new_unf :: Unfolding
new_unf | Unfolding -> Bool
isStableUnfolding Unfolding
old_unf = TidyEnv -> Unfolding -> Unfolding -> Unfolding
tidyUnfolding TidyEnv
rec_tidy_env Unfolding
old_unf Unfolding
old_unf
                | Bool
otherwise                 = Unfolding -> Unfolding
zapUnfolding Unfolding
old_unf
                                              -- See Note [Preserve evaluatedness]

    in
    ((TidyOccEnv
tidy_env', VarEnv Id
var_env'), Id
id') }

------------ Unfolding  --------------
tidyUnfolding :: TidyEnv -> Unfolding -> Unfolding -> Unfolding
tidyUnfolding :: TidyEnv -> Unfolding -> Unfolding -> Unfolding
tidyUnfolding TidyEnv
tidy_env df :: Unfolding
df@(DFunUnfolding { df_bndrs :: Unfolding -> [Id]
df_bndrs = [Id]
bndrs, df_args :: Unfolding -> [Expr Id]
df_args = [Expr Id]
args }) Unfolding
_
  = Unfolding
df { df_bndrs :: [Id]
df_bndrs = [Id]
bndrs', df_args :: [Expr Id]
df_args = forall a b. (a -> b) -> [a] -> [b]
map (TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
tidy_env') [Expr Id]
args }
  where
    (TidyEnv
tidy_env', [Id]
bndrs') = TidyEnv -> [Id] -> (TidyEnv, [Id])
tidyBndrs TidyEnv
tidy_env [Id]
bndrs

tidyUnfolding TidyEnv
tidy_env
              unf :: Unfolding
unf@(CoreUnfolding { uf_tmpl :: Unfolding -> Expr Id
uf_tmpl = Expr Id
unf_rhs, uf_src :: Unfolding -> UnfoldingSource
uf_src = UnfoldingSource
src })
              Unfolding
unf_from_rhs
  | UnfoldingSource -> Bool
isStableSource UnfoldingSource
src
  = Unfolding -> Unfolding
seqIt forall a b. (a -> b) -> a -> b
$ Unfolding
unf { uf_tmpl :: Expr Id
uf_tmpl = TidyEnv -> Expr Id -> Expr Id
tidyExpr TidyEnv
tidy_env Expr Id
unf_rhs }    -- Preserves OccInfo
    -- This seqIt avoids a space leak: otherwise the uf_is_value,
    -- uf_is_conlike, ... fields may retain a reference to the
    -- pre-tidied expression forever (GHC.CoreToIface doesn't look at them)

  | Bool
otherwise
  = Unfolding
unf_from_rhs
  where seqIt :: Unfolding -> Unfolding
seqIt Unfolding
unf = Unfolding -> ()
seqUnfolding Unfolding
unf seq :: forall a b. a -> b -> b
`seq` Unfolding
unf
tidyUnfolding TidyEnv
_ Unfolding
unf Unfolding
_ = Unfolding
unf     -- NoUnfolding or OtherCon

{-
Note [Tidy IdInfo]
~~~~~~~~~~~~~~~~~~
All nested Ids now have the same IdInfo, namely vanillaIdInfo, which
should save some space; except that we preserve occurrence info for
two reasons:

  (a) To make printing tidy core nicer

  (b) Because we tidy RULES and InlineRules, which may then propagate
      via --make into the compilation of the next module, and we want
      the benefit of that occurrence analysis when we use the rule or
      or inline the function.  In particular, it's vital not to lose
      loop-breaker info, else we get an infinite inlining loop

Note that tidyLetBndr puts more IdInfo back.

Note [Preserve evaluatedness]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  data T = MkT !Bool
  ....(case v of MkT y ->
       let z# = case y of
                  True -> 1#
                  False -> 2#
       in ...)

The z# binding is ok because the RHS is ok-for-speculation,
but Lint will complain unless it can *see* that.  So we
preserve the evaluated-ness on 'y' in tidyBndr.

(Another alternative would be to tidy unboxed lets into cases,
but that seems more indirect and surprising.)

Note [Preserve OneShotInfo]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
We keep the OneShotInfo because we want it to propagate into the interface.
Not all OneShotInfo is determined by a compiler analysis; some is added by a
call of GHC.Exts.oneShot, which is then discarded before the end of the
optimisation pipeline, leaving only the OneShotInfo on the lambda. Hence we
must preserve this info in inlinings. See Note [The oneShot function] in GHC.Types.Id.Make.

This applies to lambda binders only, hence it is stored in IfaceLamBndr.
-}

(=:) :: a -> (a -> b) -> b
a
m =: :: forall a b. a -> (a -> b) -> b
=: a -> b
k = a
m seq :: forall a b. a -> b -> b
`seq` a -> b
k a
m