{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}

-----------------------------------------------------------------------------
--
-- Stg to C-- code generation:
--
-- The types   LambdaFormInfo
--             ClosureInfo
--
-- Nothing monadic in here!
--
-----------------------------------------------------------------------------

module GHC.StgToCmm.Closure (
        DynTag,  tagForCon, isSmallFamily,

        idPrimRep, isVoidRep, isGcPtrRep, addIdReps, addArgReps,
        argPrimRep,

        NonVoid(..), fromNonVoid, nonVoidIds, nonVoidStgArgs,
        assertNonVoidIds, assertNonVoidStgArgs,

        -- * LambdaFormInfo
        LambdaFormInfo,         -- Abstract
        StandardFormInfo,        -- ...ditto...
        mkLFThunk, mkLFReEntrant, mkConLFInfo, mkSelectorLFInfo,
        mkApLFInfo, mkLFImported, mkLFArgument, mkLFLetNoEscape,
        mkLFStringLit,
        lfDynTag,
        isLFThunk, isLFReEntrant, lfUpdatable,

        -- * Used by other modules
        CgLoc(..), CallMethod(..),
        nodeMustPointToIt, isKnownFun, funTag, tagForArity,
        getCallMethod,

        -- * ClosureInfo
        ClosureInfo,
        mkClosureInfo,
        mkCmmInfo,

        -- ** Inspection
        closureLFInfo, closureName,

        -- ** Labels
        -- These just need the info table label
        closureInfoLabel, staticClosureLabel,
        closureSlowEntryLabel, closureLocalEntryLabel,

        -- ** Predicates
        -- These are really just functions on LambdaFormInfo
        closureUpdReqd,
        closureReEntrant, closureFunInfo,
        isToplevClosure,

        blackHoleOnEntry,  -- Needs LambdaFormInfo and SMRep
        isStaticClosure,   -- Needs SMPre

        -- * InfoTables
        mkDataConInfoTable,
        cafBlackHoleInfoTable,
        indStaticInfoTable,
        staticClosureNeedsLink,
        mkClosureInfoTableLabel
    ) where

import GHC.Prelude
import GHC.Platform
import GHC.Platform.Profile

import GHC.Stg.Syntax
import GHC.Runtime.Heap.Layout
import GHC.Cmm
import GHC.Cmm.Utils
import GHC.Cmm.Ppr.Expr() -- For Outputable instances
import GHC.StgToCmm.Types
import GHC.StgToCmm.Sequel

import GHC.Types.CostCentre
import GHC.Cmm.BlockId
import GHC.Cmm.CLabel
import GHC.Types.Id
import GHC.Types.Id.Info
import GHC.Core.DataCon
import GHC.Types.Name
import GHC.Core.Type
import GHC.Core.TyCo.Rep
import GHC.Tc.Utils.TcType
import GHC.Core.TyCon
import GHC.Types.RepType
import GHC.Types.Basic
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Panic.Plain
import GHC.Utils.Misc

import Data.Coerce (coerce)
import qualified Data.ByteString.Char8 as BS8
import GHC.StgToCmm.Config
import GHC.Stg.InferTags.TagSig (isTaggedSig)

-----------------------------------------------------------------------------
--                Data types and synonyms
-----------------------------------------------------------------------------

-- These data types are mostly used by other modules, especially
-- GHC.StgToCmm.Monad, but we define them here because some functions in this
-- module need to have access to them as well

data CgLoc
  = CmmLoc CmmExpr      -- A stable CmmExpr; that is, one not mentioning
                        -- Hp, so that it remains valid across calls

  | LneLoc BlockId [LocalReg]             -- A join point
        -- A join point (= let-no-escape) should only
        -- be tail-called, and in a saturated way.
        -- To tail-call it, assign to these locals,
        -- and branch to the block id

instance OutputableP Platform CgLoc where
   pdoc :: Platform -> CgLoc -> SDoc
pdoc = Platform -> CgLoc -> SDoc
pprCgLoc

pprCgLoc :: Platform -> CgLoc -> SDoc
pprCgLoc :: Platform -> CgLoc -> SDoc
pprCgLoc Platform
platform = \case
   CmmLoc CmmExpr
e    -> String -> SDoc
text String
"cmm" SDoc -> SDoc -> SDoc
<+> Platform -> CmmExpr -> SDoc
forall env a. OutputableP env a => env -> a -> SDoc
pdoc Platform
platform CmmExpr
e
   LneLoc BlockId
b [LocalReg]
rs -> String -> SDoc
text String
"lne" SDoc -> SDoc -> SDoc
<+> BlockId -> SDoc
forall a. Outputable a => a -> SDoc
ppr BlockId
b SDoc -> SDoc -> SDoc
<+> [LocalReg] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [LocalReg]
rs

-- used by ticky profiling
isKnownFun :: LambdaFormInfo -> Bool
isKnownFun :: LambdaFormInfo -> Bool
isKnownFun LFReEntrant{} = Bool
True
isKnownFun LambdaFormInfo
LFLetNoEscape = Bool
True
isKnownFun LambdaFormInfo
_             = Bool
False


-------------------------------------
--        Non-void types
-------------------------------------
-- We frequently need the invariant that an Id or a an argument
-- is of a non-void type. This type is a witness to the invariant.

newtype NonVoid a = NonVoid a
  deriving (NonVoid a -> NonVoid a -> Bool
(NonVoid a -> NonVoid a -> Bool)
-> (NonVoid a -> NonVoid a -> Bool) -> Eq (NonVoid a)
forall a. Eq a => NonVoid a -> NonVoid a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
$c== :: forall a. Eq a => NonVoid a -> NonVoid a -> Bool
== :: NonVoid a -> NonVoid a -> Bool
$c/= :: forall a. Eq a => NonVoid a -> NonVoid a -> Bool
/= :: NonVoid a -> NonVoid a -> Bool
Eq, Int -> NonVoid a -> ShowS
[NonVoid a] -> ShowS
NonVoid a -> String
(Int -> NonVoid a -> ShowS)
-> (NonVoid a -> String)
-> ([NonVoid a] -> ShowS)
-> Show (NonVoid a)
forall a. Show a => Int -> NonVoid a -> ShowS
forall a. Show a => [NonVoid a] -> ShowS
forall a. Show a => NonVoid a -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
$cshowsPrec :: forall a. Show a => Int -> NonVoid a -> ShowS
showsPrec :: Int -> NonVoid a -> ShowS
$cshow :: forall a. Show a => NonVoid a -> String
show :: NonVoid a -> String
$cshowList :: forall a. Show a => [NonVoid a] -> ShowS
showList :: [NonVoid a] -> ShowS
Show)

fromNonVoid :: NonVoid a -> a
fromNonVoid :: forall a. NonVoid a -> a
fromNonVoid (NonVoid a
a) = a
a

instance (Outputable a) => Outputable (NonVoid a) where
  ppr :: NonVoid a -> SDoc
ppr (NonVoid a
a) = a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
a

nonVoidIds :: [Id] -> [NonVoid Id]
nonVoidIds :: [Id] -> [NonVoid Id]
nonVoidIds [Id]
ids = [Id -> NonVoid Id
forall a. a -> NonVoid a
NonVoid Id
id | Id
id <- [Id]
ids, Bool -> Bool
not ((() :: Constraint) => Type -> Bool
Type -> Bool
isZeroBitTy (Id -> Type
idType Id
id))]

-- | Used in places where some invariant ensures that all these Ids are
-- non-void; e.g. constructor field binders in case expressions.
-- See Note [Post-unarisation invariants] in "GHC.Stg.Unarise".
assertNonVoidIds :: [Id] -> [NonVoid Id]
assertNonVoidIds :: [Id] -> [NonVoid Id]
assertNonVoidIds [Id]
ids = Bool -> [NonVoid Id] -> [NonVoid Id]
forall a. HasCallStack => Bool -> a -> a
assert (Bool -> Bool
not ((Id -> Bool) -> [Id] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any ((() :: Constraint) => Type -> Bool
Type -> Bool
isZeroBitTy (Type -> Bool) -> (Id -> Type) -> Id -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Id -> Type
idType) [Id]
ids)) ([NonVoid Id] -> [NonVoid Id]) -> [NonVoid Id] -> [NonVoid Id]
forall a b. (a -> b) -> a -> b
$
                       [Id] -> [NonVoid Id]
forall a b. Coercible a b => a -> b
coerce [Id]
ids

nonVoidStgArgs :: [StgArg] -> [NonVoid StgArg]
nonVoidStgArgs :: [StgArg] -> [NonVoid StgArg]
nonVoidStgArgs [StgArg]
args = [StgArg -> NonVoid StgArg
forall a. a -> NonVoid a
NonVoid StgArg
arg | StgArg
arg <- [StgArg]
args, Bool -> Bool
not ((() :: Constraint) => Type -> Bool
Type -> Bool
isZeroBitTy (StgArg -> Type
stgArgType StgArg
arg))]

-- | Used in places where some invariant ensures that all these arguments are
-- non-void; e.g. constructor arguments.
-- See Note [Post-unarisation invariants] in "GHC.Stg.Unarise".
assertNonVoidStgArgs :: [StgArg] -> [NonVoid StgArg]
assertNonVoidStgArgs :: [StgArg] -> [NonVoid StgArg]
assertNonVoidStgArgs [StgArg]
args = Bool -> [NonVoid StgArg] -> [NonVoid StgArg]
forall a. HasCallStack => Bool -> a -> a
assert (Bool -> Bool
not ((StgArg -> Bool) -> [StgArg] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any ((() :: Constraint) => Type -> Bool
Type -> Bool
isZeroBitTy (Type -> Bool) -> (StgArg -> Type) -> StgArg -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. StgArg -> Type
stgArgType) [StgArg]
args)) ([NonVoid StgArg] -> [NonVoid StgArg])
-> [NonVoid StgArg] -> [NonVoid StgArg]
forall a b. (a -> b) -> a -> b
$
                            [StgArg] -> [NonVoid StgArg]
forall a b. Coercible a b => a -> b
coerce [StgArg]
args


-----------------------------------------------------------------------------
--                Representations
-----------------------------------------------------------------------------

-- Why are these here?

-- | Assumes that there is precisely one 'PrimRep' of the type. This assumption
-- holds after unarise.
-- See Note [Post-unarisation invariants]
idPrimRep :: Id -> PrimRep
idPrimRep :: Id -> PrimRep
idPrimRep Id
id = (() :: Constraint) => Type -> PrimRep
Type -> PrimRep
typePrimRep1 (Id -> Type
idType Id
id)
    -- See also Note [VoidRep] in GHC.Types.RepType

-- | Assumes that Ids have one PrimRep, which holds after unarisation.
-- See Note [Post-unarisation invariants]
addIdReps :: [NonVoid Id] -> [NonVoid (PrimRep, Id)]
addIdReps :: [NonVoid Id] -> [NonVoid (PrimRep, Id)]
addIdReps = (NonVoid Id -> NonVoid (PrimRep, Id))
-> [NonVoid Id] -> [NonVoid (PrimRep, Id)]
forall a b. (a -> b) -> [a] -> [b]
map (\NonVoid Id
id -> let id' :: Id
id' = NonVoid Id -> Id
forall a. NonVoid a -> a
fromNonVoid NonVoid Id
id
                         in (PrimRep, Id) -> NonVoid (PrimRep, Id)
forall a. a -> NonVoid a
NonVoid (Id -> PrimRep
idPrimRep Id
id', Id
id'))

-- | Assumes that arguments have one PrimRep, which holds after unarisation.
-- See Note [Post-unarisation invariants]
addArgReps :: [NonVoid StgArg] -> [NonVoid (PrimRep, StgArg)]
addArgReps :: [NonVoid StgArg] -> [NonVoid (PrimRep, StgArg)]
addArgReps = (NonVoid StgArg -> NonVoid (PrimRep, StgArg))
-> [NonVoid StgArg] -> [NonVoid (PrimRep, StgArg)]
forall a b. (a -> b) -> [a] -> [b]
map (\NonVoid StgArg
arg -> let arg' :: StgArg
arg' = NonVoid StgArg -> StgArg
forall a. NonVoid a -> a
fromNonVoid NonVoid StgArg
arg
                           in (PrimRep, StgArg) -> NonVoid (PrimRep, StgArg)
forall a. a -> NonVoid a
NonVoid (StgArg -> PrimRep
argPrimRep StgArg
arg', StgArg
arg'))

-- | Assumes that the argument has one PrimRep, which holds after unarisation.
-- See Note [Post-unarisation invariants]
argPrimRep :: StgArg -> PrimRep
argPrimRep :: StgArg -> PrimRep
argPrimRep StgArg
arg = (() :: Constraint) => Type -> PrimRep
Type -> PrimRep
typePrimRep1 (StgArg -> Type
stgArgType StgArg
arg)

------------------------------------------------------
--                Building LambdaFormInfo
------------------------------------------------------

mkLFArgument :: Id -> LambdaFormInfo
mkLFArgument :: Id -> LambdaFormInfo
mkLFArgument Id
id
  | (() :: Constraint) => Type -> Bool
Type -> Bool
isUnliftedType Type
ty      = LambdaFormInfo
LFUnlifted
  | Type -> Bool
might_be_a_function Type
ty = Bool -> LambdaFormInfo
LFUnknown Bool
True
  | Bool
otherwise              = Bool -> LambdaFormInfo
LFUnknown Bool
False
  where
    ty :: Type
ty = Id -> Type
idType Id
id

-------------
mkLFLetNoEscape :: LambdaFormInfo
mkLFLetNoEscape :: LambdaFormInfo
mkLFLetNoEscape = LambdaFormInfo
LFLetNoEscape

-------------
mkLFReEntrant :: TopLevelFlag    -- True of top level
              -> [Id]            -- Free vars
              -> [Id]            -- Args
              -> ArgDescr        -- Argument descriptor
              -> LambdaFormInfo

mkLFReEntrant :: TopLevelFlag -> [Id] -> [Id] -> ArgDescr -> LambdaFormInfo
mkLFReEntrant TopLevelFlag
_ [Id]
_ [] ArgDescr
_
  = String -> SDoc -> LambdaFormInfo
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"mkLFReEntrant" SDoc
empty
mkLFReEntrant TopLevelFlag
top [Id]
fvs [Id]
args ArgDescr
arg_descr
  = TopLevelFlag -> Int -> Bool -> ArgDescr -> LambdaFormInfo
LFReEntrant TopLevelFlag
top ([Id] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Id]
args) ([Id] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Id]
fvs) ArgDescr
arg_descr

-------------
mkLFThunk :: Type -> TopLevelFlag -> [Id] -> UpdateFlag -> LambdaFormInfo
mkLFThunk :: Type -> TopLevelFlag -> [Id] -> UpdateFlag -> LambdaFormInfo
mkLFThunk Type
thunk_ty TopLevelFlag
top [Id]
fvs UpdateFlag
upd_flag
  = Bool -> LambdaFormInfo -> LambdaFormInfo
forall a. HasCallStack => Bool -> a -> a
assert (Bool -> Bool
not (UpdateFlag -> Bool
isUpdatable UpdateFlag
upd_flag) Bool -> Bool -> Bool
|| Bool -> Bool
not ((() :: Constraint) => Type -> Bool
Type -> Bool
isUnliftedType Type
thunk_ty)) (LambdaFormInfo -> LambdaFormInfo)
-> LambdaFormInfo -> LambdaFormInfo
forall a b. (a -> b) -> a -> b
$
    TopLevelFlag
-> Bool -> Bool -> StandardFormInfo -> Bool -> LambdaFormInfo
LFThunk TopLevelFlag
top ([Id] -> Bool
forall a. [a] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Id]
fvs)
            (UpdateFlag -> Bool
isUpdatable UpdateFlag
upd_flag)
            StandardFormInfo
NonStandardThunk
            (Type -> Bool
might_be_a_function Type
thunk_ty)

--------------
might_be_a_function :: Type -> Bool
-- Return False only if we are *sure* it's a data type
-- Look through newtypes etc as much as poss
might_be_a_function :: Type -> Bool
might_be_a_function Type
ty
  | [PrimRep
LiftedRep] <- (() :: Constraint) => Type -> [PrimRep]
Type -> [PrimRep]
typePrimRep Type
ty
  , Just TyCon
tc <- Type -> Maybe TyCon
tyConAppTyCon_maybe (Type -> Type
unwrapType Type
ty)
  , TyCon -> Bool
isDataTyCon TyCon
tc
  = Bool
False
  | Bool
otherwise
  = Bool
True

-------------
mkConLFInfo :: DataCon -> LambdaFormInfo
mkConLFInfo :: DataCon -> LambdaFormInfo
mkConLFInfo DataCon
con = DataCon -> LambdaFormInfo
LFCon DataCon
con

-------------
mkSelectorLFInfo :: Id -> Int -> Bool -> LambdaFormInfo
mkSelectorLFInfo :: Id -> Int -> Bool -> LambdaFormInfo
mkSelectorLFInfo Id
id Int
offset Bool
updatable
  = TopLevelFlag
-> Bool -> Bool -> StandardFormInfo -> Bool -> LambdaFormInfo
LFThunk TopLevelFlag
NotTopLevel Bool
False Bool
updatable (Int -> StandardFormInfo
SelectorThunk Int
offset)
        (Type -> Bool
might_be_a_function (Id -> Type
idType Id
id))

-------------
mkApLFInfo :: Id -> UpdateFlag -> Arity -> LambdaFormInfo
mkApLFInfo :: Id -> UpdateFlag -> Int -> LambdaFormInfo
mkApLFInfo Id
id UpdateFlag
upd_flag Int
arity
  = TopLevelFlag
-> Bool -> Bool -> StandardFormInfo -> Bool -> LambdaFormInfo
LFThunk TopLevelFlag
NotTopLevel (Int
arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) (UpdateFlag -> Bool
isUpdatable UpdateFlag
upd_flag) (Int -> StandardFormInfo
ApThunk Int
arity)
        (Type -> Bool
might_be_a_function (Id -> Type
idType Id
id))

-------------
mkLFImported :: Id -> LambdaFormInfo
mkLFImported :: Id -> LambdaFormInfo
mkLFImported Id
id =
    -- See Note [Conveying CAF-info and LFInfo between modules] in
    -- GHC.StgToCmm.Types
    case Id -> Maybe LambdaFormInfo
idLFInfo_maybe Id
id of
      Just LambdaFormInfo
lf_info ->
        -- Use the LambdaFormInfo from the interface
        LambdaFormInfo
lf_info
      Maybe LambdaFormInfo
Nothing
        -- Interface doesn't have a LambdaFormInfo, make a conservative one from
        -- the type.
        | Just DataCon
con <- Id -> Maybe DataCon
isDataConWorkId_maybe Id
id
        , DataCon -> Bool
isNullaryRepDataCon DataCon
con
        -> DataCon -> LambdaFormInfo
LFCon DataCon
con   -- An imported nullary constructor
                       -- We assume that the constructor is evaluated so that
                       -- the id really does point directly to the constructor

        | Int
arity Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
> Int
0
        -> TopLevelFlag -> Int -> Bool -> ArgDescr -> LambdaFormInfo
LFReEntrant TopLevelFlag
TopLevel Int
arity Bool
True ArgDescr
ArgUnknown

        | Bool
otherwise
        -> Id -> LambdaFormInfo
mkLFArgument Id
id -- Not sure of exact arity
  where
    arity :: Int
arity = Id -> Int
idFunRepArity Id
id

-------------
mkLFStringLit :: LambdaFormInfo
mkLFStringLit :: LambdaFormInfo
mkLFStringLit = LambdaFormInfo
LFUnlifted

-----------------------------------------------------
--                Dynamic pointer tagging
-----------------------------------------------------

type DynTag = Int       -- The tag on a *pointer*
                        -- (from the dynamic-tagging paper)

-- Note [Data constructor dynamic tags]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- The family size of a data type (the number of constructors
-- or the arity of a function) can be either:
--    * small, if the family size < 2**tag_bits
--    * big, otherwise.
--
-- Small families can have the constructor tag in the tag bits.
-- Big families always use the tag values 1..mAX_PTR_TAG to represent
-- evaluatedness, the last one lumping together all overflowing ones.
-- We don't have very many tag bits: for example, we have 2 bits on
-- x86-32 and 3 bits on x86-64.
--
-- Also see Note [Tagging big families] in GHC.StgToCmm.Expr
--
-- The interpreter also needs to be updated if we change the
-- tagging strategy. See Note [Data constructor dynamic tags] in
-- rts/Interpreter.c

isSmallFamily :: Platform -> Int -> Bool
isSmallFamily :: Platform -> Int -> Bool
isSmallFamily Platform
platform Int
fam_size = Int
fam_size Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
<= Platform -> Int
mAX_PTR_TAG Platform
platform

tagForCon :: Platform -> DataCon -> DynTag
tagForCon :: Platform -> DataCon -> Int
tagForCon Platform
platform DataCon
con = Int -> Int -> Int
forall a. Ord a => a -> a -> a
min (DataCon -> Int
dataConTag DataCon
con) (Platform -> Int
mAX_PTR_TAG Platform
platform)
-- NB: 1-indexed

tagForArity :: Platform -> RepArity -> DynTag
tagForArity :: Platform -> Int -> Int
tagForArity Platform
platform Int
arity
 | Platform -> Int -> Bool
isSmallFamily Platform
platform Int
arity = Int
arity
 | Bool
otherwise                    = Int
0

-- | Return the tag in the low order bits of a variable bound
-- to this LambdaForm
lfDynTag :: Platform -> LambdaFormInfo -> DynTag
lfDynTag :: Platform -> LambdaFormInfo -> Int
lfDynTag Platform
platform LambdaFormInfo
lf = case LambdaFormInfo
lf of
   LFCon DataCon
con               -> Platform -> DataCon -> Int
tagForCon   Platform
platform DataCon
con
   LFReEntrant TopLevelFlag
_ Int
arity Bool
_ ArgDescr
_ -> Platform -> Int -> Int
tagForArity Platform
platform Int
arity
   LambdaFormInfo
_other                  -> Int
0


-----------------------------------------------------------------------------
--                Observing LambdaFormInfo
-----------------------------------------------------------------------------

------------
isLFThunk :: LambdaFormInfo -> Bool
isLFThunk :: LambdaFormInfo -> Bool
isLFThunk (LFThunk {})  = Bool
True
isLFThunk LambdaFormInfo
_ = Bool
False

isLFReEntrant :: LambdaFormInfo -> Bool
isLFReEntrant :: LambdaFormInfo -> Bool
isLFReEntrant (LFReEntrant {}) = Bool
True
isLFReEntrant LambdaFormInfo
_                = Bool
False

-----------------------------------------------------------------------------
--                Choosing SM reps
-----------------------------------------------------------------------------

lfClosureType :: LambdaFormInfo -> ClosureTypeInfo
lfClosureType :: LambdaFormInfo -> ClosureTypeInfo
lfClosureType (LFReEntrant TopLevelFlag
_ Int
arity Bool
_ ArgDescr
argd) = Int -> ArgDescr -> ClosureTypeInfo
Fun Int
arity ArgDescr
argd
lfClosureType (LFCon DataCon
con)                  = Int -> ConstrDescription -> ClosureTypeInfo
Constr (DataCon -> Int
dataConTagZ DataCon
con)
                                                    (DataCon -> ConstrDescription
dataConIdentity DataCon
con)
lfClosureType (LFThunk TopLevelFlag
_ Bool
_ Bool
_ StandardFormInfo
is_sel Bool
_)     = StandardFormInfo -> ClosureTypeInfo
thunkClosureType StandardFormInfo
is_sel
lfClosureType LambdaFormInfo
_                            = String -> ClosureTypeInfo
forall a. String -> a
panic String
"lfClosureType"

thunkClosureType :: StandardFormInfo -> ClosureTypeInfo
thunkClosureType :: StandardFormInfo -> ClosureTypeInfo
thunkClosureType (SelectorThunk Int
off) = Int -> ClosureTypeInfo
ThunkSelector Int
off
thunkClosureType StandardFormInfo
_                   = ClosureTypeInfo
Thunk

-- We *do* get non-updatable top-level thunks sometimes.  eg. f = g
-- gets compiled to a jump to g (if g has non-zero arity), instead of
-- messing around with update frames and PAPs.  We set the closure type
-- to FUN_STATIC in this case.

-----------------------------------------------------------------------------
--                nodeMustPointToIt
-----------------------------------------------------------------------------

nodeMustPointToIt :: Profile -> LambdaFormInfo -> Bool
-- If nodeMustPointToIt is true, then the entry convention for
-- this closure has R1 (the "Node" register) pointing to the
-- closure itself --- the "self" argument

nodeMustPointToIt :: Profile -> LambdaFormInfo -> Bool
nodeMustPointToIt Profile
_ (LFReEntrant TopLevelFlag
top Int
_ Bool
no_fvs ArgDescr
_)
  =  Bool -> Bool
not Bool
no_fvs          -- Certainly if it has fvs we need to point to it
  Bool -> Bool -> Bool
|| TopLevelFlag -> Bool
isNotTopLevel TopLevelFlag
top   -- See Note [GC recovery]
        -- For lex_profiling we also access the cost centre for a
        -- non-inherited (i.e. non-top-level) function.
        -- The isNotTopLevel test above ensures this is ok.

nodeMustPointToIt Profile
profile (LFThunk TopLevelFlag
top Bool
no_fvs Bool
updatable StandardFormInfo
NonStandardThunk Bool
_)
  =  Bool -> Bool
not Bool
no_fvs            -- Self parameter
  Bool -> Bool -> Bool
|| TopLevelFlag -> Bool
isNotTopLevel TopLevelFlag
top     -- Note [GC recovery]
  Bool -> Bool -> Bool
|| Bool
updatable             -- Need to push update frame
  Bool -> Bool -> Bool
|| Profile -> Bool
profileIsProfiling Profile
profile
          -- For the non-updatable (single-entry case):
          --
          -- True if has fvs (in which case we need access to them, and we
          --                    should black-hole it)
          -- or profiling (in which case we need to recover the cost centre
          --                 from inside it)  ToDo: do we need this even for
          --                                    top-level thunks? If not,
          --                                    isNotTopLevel subsumes this

nodeMustPointToIt Profile
_ (LFThunk {})        -- Node must point to a standard-form thunk
  = Bool
True

nodeMustPointToIt Profile
_ (LFCon DataCon
_) = Bool
True

        -- Strictly speaking, the above two don't need Node to point
        -- to it if the arity = 0.  But this is a *really* unlikely
        -- situation.  If we know it's nil (say) and we are entering
        -- it. Eg: let x = [] in x then we will certainly have inlined
        -- x, since nil is a simple atom.  So we gain little by not
        -- having Node point to known zero-arity things.  On the other
        -- hand, we do lose something; Patrick's code for figuring out
        -- when something has been updated but not entered relies on
        -- having Node point to the result of an update.  SLPJ
        -- 27/11/92.

nodeMustPointToIt Profile
_ (LFUnknown Bool
_)   = Bool
True
nodeMustPointToIt Profile
_ LambdaFormInfo
LFUnlifted      = Bool
False
nodeMustPointToIt Profile
_ LambdaFormInfo
LFLetNoEscape   = Bool
False

{- Note [GC recovery]
~~~~~~~~~~~~~~~~~~~~~
If we a have a local let-binding (function or thunk)
   let f = <body> in ...
AND <body> allocates, then the heap-overflow check needs to know how
to re-start the evaluation.  It uses the "self" pointer to do this.
So even if there are no free variables in <body>, we still make
nodeMustPointToIt be True for non-top-level bindings.

Why do any such bindings exist?  After all, let-floating should have
floated them out.  Well, a clever optimiser might leave one there to
avoid a space leak, deliberately recomputing a thunk.  Also (and this
really does happen occasionally) let-floating may make a function f smaller
so it can be inlined, so now (f True) may generate a local no-fv closure.
This actually happened during bootstrapping GHC itself, with f=mkRdrFunBind
in GHC.Tc.Deriv.Generate.) -}

-----------------------------------------------------------------------------
--                getCallMethod
-----------------------------------------------------------------------------

{- The entry conventions depend on the type of closure being entered,
whether or not it has free variables, and whether we're running
sequentially or in parallel.

Closure                           Node   Argument   Enter
Characteristics              Par   Req'd  Passing    Via
---------------------------------------------------------------------------
Unknown                     & no  & yes & stack     & node
Known fun (>1 arg), no fvs  & no  & no  & registers & fast entry (enough args)
                                                    & slow entry (otherwise)
Known fun (>1 arg), fvs     & no  & yes & registers & fast entry (enough args)
0 arg, no fvs \r,\s         & no  & no  & n/a       & direct entry
0 arg, no fvs \u            & no  & yes & n/a       & node
0 arg, fvs \r,\s,selector   & no  & yes & n/a       & node
0 arg, fvs \r,\s            & no  & yes & n/a       & direct entry
0 arg, fvs \u               & no  & yes & n/a       & node
Unknown                     & yes & yes & stack     & node
Known fun (>1 arg), no fvs  & yes & no  & registers & fast entry (enough args)
                                                    & slow entry (otherwise)
Known fun (>1 arg), fvs     & yes & yes & registers & node
0 arg, fvs \r,\s,selector   & yes & yes & n/a       & node
0 arg, no fvs \r,\s         & yes & no  & n/a       & direct entry
0 arg, no fvs \u            & yes & yes & n/a       & node
0 arg, fvs \r,\s            & yes & yes & n/a       & node
0 arg, fvs \u               & yes & yes & n/a       & node

When black-holing, single-entry closures could also be entered via node
(rather than directly) to catch double-entry. -}

data CallMethod
  = EnterIt             -- ^ No args, not a function

  | JumpToIt BlockId [LocalReg] -- A join point or a header of a local loop

  | ReturnIt            -- It's a value (function, unboxed value,
                        -- or constructor), so just return it.

  | InferedReturnIt     -- A properly tagged value, as determined by tag inference.
                        -- See Note [Tag Inference] and Note [Tag inference passes] in
                        -- GHC.Stg.InferTags.
                        -- It behaves /precisely/ like `ReturnIt`, except that when debugging is
                        -- enabled we emit an extra assertion to check that the returned value is
                        -- properly tagged.  We can use this as a check that tag inference is working
                        -- correctly.
                        -- TODO: SPJ suggested we could combine this with EnterIt, but for now I decided
                        -- not to do so.

  | SlowCall            -- Unknown fun, or known fun with
                        -- too few args.

  | DirectEntry         -- Jump directly, with args in regs
        CLabel          --   The code label
        RepArity        --   Its arity

instance Outputable CallMethod where
  ppr :: CallMethod -> SDoc
ppr (CallMethod
EnterIt) = String -> SDoc
text String
"Enter"
  ppr (JumpToIt {}) = String -> SDoc
text String
"JumpToIt"
  ppr (CallMethod
ReturnIt ) = String -> SDoc
text String
"ReturnIt"
  ppr (CallMethod
InferedReturnIt) = String -> SDoc
text String
"InferedReturnIt"
  ppr (CallMethod
SlowCall ) = String -> SDoc
text String
"SlowCall"
  ppr (DirectEntry {}) = String -> SDoc
text String
"DirectEntry"

getCallMethod :: StgToCmmConfig
              -> Name           -- Function being applied
              -> Id             -- Function Id used to chech if it can refer to
                                -- CAF's and whether the function is tail-calling
                                -- itself
              -> LambdaFormInfo -- Its info
              -> RepArity       -- Number of available arguments
              -> RepArity       -- Number of them being void arguments
              -> CgLoc          -- Passed in from cgIdApp so that we can
                                -- handle let-no-escape bindings and self-recursive
                                -- tail calls using the same data constructor,
                                -- JumpToIt. This saves us one case branch in
                                -- cgIdApp
              -> Maybe SelfLoopInfo -- can we perform a self-recursive tail-call
              -> CallMethod

getCallMethod :: StgToCmmConfig
-> Name
-> Id
-> LambdaFormInfo
-> Int
-> Int
-> CgLoc
-> Maybe SelfLoopInfo
-> CallMethod
getCallMethod StgToCmmConfig
cfg Name
_ Id
id LambdaFormInfo
_  Int
n_args Int
v_args CgLoc
_cg_loc (Just (Id
self_loop_id, BlockId
block_id, [LocalReg]
args))
  | StgToCmmConfig -> Bool
stgToCmmLoopification StgToCmmConfig
cfg
  , Id
id Id -> Id -> Bool
forall a. Eq a => a -> a -> Bool
== Id
self_loop_id
  , [LocalReg]
args [LocalReg] -> Int -> Bool
forall a. [a] -> Int -> Bool
`lengthIs` (Int
n_args Int -> Int -> Int
forall a. Num a => a -> a -> a
- Int
v_args)
  -- If these patterns match then we know that:
  --   * loopification optimisation is turned on
  --   * function is performing a self-recursive call in a tail position
  --   * number of non-void parameters of the function matches functions arity.
  -- See Note [Self-recursive tail calls] and Note [Void arguments in
  -- self-recursive tail calls] in GHC.StgToCmm.Expr for more details
  = BlockId -> [LocalReg] -> CallMethod
JumpToIt BlockId
block_id [LocalReg]
args

getCallMethod StgToCmmConfig
cfg Name
name Id
id (LFReEntrant TopLevelFlag
_ Int
arity Bool
_ ArgDescr
_) Int
n_args Int
_v_args CgLoc
_cg_loc Maybe SelfLoopInfo
_self_loop_info
  | Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0 -- No args at all
  Bool -> Bool -> Bool
&& Bool -> Bool
not (Profile -> Bool
profileIsProfiling (StgToCmmConfig -> Profile
stgToCmmProfile StgToCmmConfig
cfg))
     -- See Note [Evaluating functions with profiling] in rts/Apply.cmm
  = Bool -> CallMethod -> CallMethod
forall a. HasCallStack => Bool -> a -> a
assert (Int
arity Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
/= Int
0) CallMethod
ReturnIt
  | Int
n_args Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
< Int
arity = CallMethod
SlowCall        -- Not enough args
  | Bool
otherwise      = CLabel -> Int -> CallMethod
DirectEntry (Platform -> Name -> CafInfo -> CLabel
enterIdLabel (StgToCmmConfig -> Platform
stgToCmmPlatform StgToCmmConfig
cfg) Name
name (Id -> CafInfo
idCafInfo Id
id)) Int
arity

getCallMethod StgToCmmConfig
_ Name
_name Id
_ LambdaFormInfo
LFUnlifted Int
n_args Int
_v_args CgLoc
_cg_loc Maybe SelfLoopInfo
_self_loop_info
  = Bool -> CallMethod -> CallMethod
forall a. HasCallStack => Bool -> a -> a
assert (Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) CallMethod
ReturnIt

getCallMethod StgToCmmConfig
_ Name
_name Id
_ (LFCon DataCon
_) Int
n_args Int
_v_args CgLoc
_cg_loc Maybe SelfLoopInfo
_self_loop_info
  = Bool -> CallMethod -> CallMethod
forall a. HasCallStack => Bool -> a -> a
assert (Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) CallMethod
ReturnIt
    -- n_args=0 because it'd be ill-typed to apply a saturated
    --          constructor application to anything

getCallMethod StgToCmmConfig
cfg Name
name Id
id (LFThunk TopLevelFlag
_ Bool
_ Bool
updatable StandardFormInfo
std_form_info Bool
is_fun)
              Int
n_args Int
_v_args CgLoc
_cg_loc Maybe SelfLoopInfo
_self_loop_info

  | Just TagSig
sig <- Id -> Maybe TagSig
idTagSig_maybe Id
id
  , TagSig -> Bool
isTaggedSig TagSig
sig -- Infered to be already evaluated by Tag Inference
  , Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0     -- See Note [Tag Inference]
  = CallMethod
InferedReturnIt

  | Bool
is_fun      -- it *might* be a function, so we must "call" it (which is always safe)
  = CallMethod
SlowCall    -- We cannot just enter it [in eval/apply, the entry code
                -- is the fast-entry code]

  -- Since is_fun is False, we are *definitely* looking at a data value
  | Bool
updatable Bool -> Bool -> Bool
|| StgToCmmConfig -> Bool
stgToCmmDoTicky StgToCmmConfig
cfg -- to catch double entry
      {- OLD: || opt_SMP
         I decided to remove this, because in SMP mode it doesn't matter
         if we enter the same thunk multiple times, so the optimisation
         of jumping directly to the entry code is still valid.  --SDM
        -}
  = CallMethod
EnterIt

  -- even a non-updatable selector thunk can be updated by the garbage
  -- collector, so we must enter it. (#8817)
  | SelectorThunk{} <- StandardFormInfo
std_form_info
  = CallMethod
EnterIt

    -- We used to have assert (n_args == 0 ), but actually it is
    -- possible for the optimiser to generate
    --   let bot :: Int = error Int "urk"
    --   in (bot `cast` unsafeCoerce Int (Int -> Int)) 3
    -- This happens as a result of the case-of-error transformation
    -- So the right thing to do is just to enter the thing

  | Bool
otherwise        -- Jump direct to code for single-entry thunks
  = Bool -> CallMethod -> CallMethod
forall a. HasCallStack => Bool -> a -> a
assert (Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) (CallMethod -> CallMethod) -> CallMethod -> CallMethod
forall a b. (a -> b) -> a -> b
$
    CLabel -> Int -> CallMethod
DirectEntry (Platform -> Name -> CafInfo -> StandardFormInfo -> Bool -> CLabel
thunkEntryLabel (StgToCmmConfig -> Platform
stgToCmmPlatform StgToCmmConfig
cfg) Name
name (Id -> CafInfo
idCafInfo Id
id) StandardFormInfo
std_form_info
                Bool
updatable) Int
0

-- Imported(Unknown) Ids
getCallMethod StgToCmmConfig
cfg Name
name Id
id (LFUnknown Bool
might_be_a_function) Int
n_args Int
_v_args CgLoc
_cg_locs Maybe SelfLoopInfo
_self_loop_info
  | Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0
  , Just TagSig
sig <- Id -> Maybe TagSig
idTagSig_maybe Id
id
  , TagSig -> Bool
isTaggedSig TagSig
sig -- Infered to be already evaluated by Tag Inference
  -- When profiling we enter functions to update the SCC so we
  -- can't use the infered enterInfo here.
  -- See Note [Evaluating functions with profiling] in rts/Apply.cmm
  , Bool -> Bool
not (Profile -> Bool
profileIsProfiling (StgToCmmConfig -> Profile
stgToCmmProfile StgToCmmConfig
cfg) Bool -> Bool -> Bool
&& Bool
might_be_a_function)
  = CallMethod
InferedReturnIt -- See Note [Tag Inference]

  | Bool
might_be_a_function = CallMethod
SlowCall

  | Bool
otherwise =
      Bool -> SDoc -> CallMethod -> CallMethod
forall a. HasCallStack => Bool -> SDoc -> a -> a
assertPpr ( Int
n_args Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== Int
0) ( Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
<+> Int -> SDoc
forall a. Outputable a => a -> SDoc
ppr Int
n_args )
      CallMethod
EnterIt   -- Not a function

-- TODO: Redundant with above match?
-- getCallMethod _ name _ (LFUnknown False) n_args _v_args _cg_loc _self_loop_info
--   = assertPpr (n_args == 0) (ppr name <+> ppr n_args)
--     EnterIt -- Not a function

getCallMethod StgToCmmConfig
_ Name
_name Id
_ LambdaFormInfo
LFLetNoEscape Int
_n_args Int
_v_args (LneLoc BlockId
blk_id [LocalReg]
lne_regs) Maybe SelfLoopInfo
_self_loop_info
  = BlockId -> [LocalReg] -> CallMethod
JumpToIt BlockId
blk_id [LocalReg]
lne_regs

getCallMethod StgToCmmConfig
_ Name
_ Id
_ LambdaFormInfo
_ Int
_ Int
_ CgLoc
_ Maybe SelfLoopInfo
_ = String -> CallMethod
forall a. String -> a
panic String
"Unknown call method"

-----------------------------------------------------------------------------
--              Data types for closure information
-----------------------------------------------------------------------------


{- ClosureInfo: information about a binding

   We make a ClosureInfo for each let binding (both top level and not),
   but not bindings for data constructors: for those we build a CmmInfoTable
   directly (see mkDataConInfoTable).

   To a first approximation:
       ClosureInfo = (LambdaFormInfo, CmmInfoTable)

   A ClosureInfo has enough information
     a) to construct the info table itself, and build other things
        related to the binding (e.g. slow entry points for a function)
     b) to allocate a closure containing that info pointer (i.e.
           it knows the info table label)
-}

data ClosureInfo
  = ClosureInfo {
        ClosureInfo -> Id
closureName :: !Id,           -- The thing bound to this closure
           -- we don't really need this field: it's only used in generating
           -- code for ticky and profiling, and we could pass the information
           -- around separately, but it doesn't do much harm to keep it here.

        ClosureInfo -> LambdaFormInfo
closureLFInfo :: !LambdaFormInfo, -- NOTE: not an LFCon
          -- this tells us about what the closure contains: it's right-hand-side.

          -- the rest is just an unpacked CmmInfoTable.
        ClosureInfo -> CLabel
closureInfoLabel :: !CLabel,
        ClosureInfo -> SMRep
closureSMRep     :: !SMRep,          -- representation used by storage mgr
        ClosureInfo -> ProfilingInfo
closureProf      :: !ProfilingInfo
    }

-- | Convert from 'ClosureInfo' to 'CmmInfoTable'.
mkCmmInfo :: ClosureInfo -> Id -> CostCentreStack -> CmmInfoTable
mkCmmInfo :: ClosureInfo -> Id -> CostCentreStack -> CmmInfoTable
mkCmmInfo ClosureInfo {Id
CLabel
SMRep
LambdaFormInfo
ProfilingInfo
closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureName :: ClosureInfo -> Id
closureInfoLabel :: ClosureInfo -> CLabel
closureSMRep :: ClosureInfo -> SMRep
closureProf :: ClosureInfo -> ProfilingInfo
closureName :: Id
closureLFInfo :: LambdaFormInfo
closureInfoLabel :: CLabel
closureSMRep :: SMRep
closureProf :: ProfilingInfo
..} Id
id CostCentreStack
ccs
  = CmmInfoTable { cit_lbl :: CLabel
cit_lbl  = CLabel
closureInfoLabel
                 , cit_rep :: SMRep
cit_rep  = SMRep
closureSMRep
                 , cit_prof :: ProfilingInfo
cit_prof = ProfilingInfo
closureProf
                 , cit_srt :: Maybe CLabel
cit_srt  = Maybe CLabel
forall a. Maybe a
Nothing
                 , cit_clo :: Maybe (Id, CostCentreStack)
cit_clo  = if SMRep -> Bool
isStaticRep SMRep
closureSMRep
                                then (Id, CostCentreStack) -> Maybe (Id, CostCentreStack)
forall a. a -> Maybe a
Just (Id
id,CostCentreStack
ccs)
                                else Maybe (Id, CostCentreStack)
forall a. Maybe a
Nothing }

--------------------------------------
--        Building ClosureInfos
--------------------------------------

mkClosureInfo :: Profile
              -> Bool                -- Is static
              -> Id
              -> LambdaFormInfo
              -> Int -> Int        -- Total and pointer words
              -> String         -- String descriptor
              -> ClosureInfo
mkClosureInfo :: Profile
-> Bool
-> Id
-> LambdaFormInfo
-> Int
-> Int
-> String
-> ClosureInfo
mkClosureInfo Profile
profile Bool
is_static Id
id LambdaFormInfo
lf_info Int
tot_wds Int
ptr_wds String
val_descr
  = ClosureInfo { closureName :: Id
closureName      = Id
id
                , closureLFInfo :: LambdaFormInfo
closureLFInfo    = LambdaFormInfo
lf_info
                , closureInfoLabel :: CLabel
closureInfoLabel = CLabel
info_lbl   -- These three fields are
                , closureSMRep :: SMRep
closureSMRep     = SMRep
sm_rep     -- (almost) an info table
                , closureProf :: ProfilingInfo
closureProf      = ProfilingInfo
prof }     -- (we don't have an SRT yet)
  where
    sm_rep :: SMRep
sm_rep     = Profile -> Bool -> Int -> Int -> ClosureTypeInfo -> SMRep
mkHeapRep Profile
profile Bool
is_static Int
ptr_wds Int
nonptr_wds (LambdaFormInfo -> ClosureTypeInfo
lfClosureType LambdaFormInfo
lf_info)
    prof :: ProfilingInfo
prof       = Profile -> Id -> String -> ProfilingInfo
mkProfilingInfo Profile
profile Id
id String
val_descr
    nonptr_wds :: Int
nonptr_wds = Int
tot_wds Int -> Int -> Int
forall a. Num a => a -> a -> a
- Int
ptr_wds

    info_lbl :: CLabel
info_lbl = Platform -> Id -> LambdaFormInfo -> CLabel
mkClosureInfoTableLabel (Profile -> Platform
profilePlatform Profile
profile) Id
id LambdaFormInfo
lf_info

--------------------------------------
--   Other functions over ClosureInfo
--------------------------------------

-- Eager blackholing is normally disabled, but can be turned on with
-- -feager-blackholing.  When it is on, we replace the info pointer of
-- the thunk with stg_EAGER_BLACKHOLE_info on entry.

-- If we wanted to do eager blackholing with slop filling,
-- we'd need to do it at the *end* of a basic block, otherwise
-- we overwrite the free variables in the thunk that we still
-- need.  We have a patch for this from Andy Cheadle, but not
-- incorporated yet. --SDM [6/2004]
--
-- Previously, eager blackholing was enabled when ticky-ticky
-- was on. But it didn't work, and it wasn't strictly necessary
-- to bring back minimal ticky-ticky, so now EAGER_BLACKHOLING
-- is unconditionally disabled. -- krc 1/2007
--
-- Static closures are never themselves black-holed.

blackHoleOnEntry :: ClosureInfo -> Bool
blackHoleOnEntry :: ClosureInfo -> Bool
blackHoleOnEntry ClosureInfo
cl_info
  | SMRep -> Bool
isStaticRep (ClosureInfo -> SMRep
closureSMRep ClosureInfo
cl_info)
  = Bool
False        -- Never black-hole a static closure

  | Bool
otherwise
  = case ClosureInfo -> LambdaFormInfo
closureLFInfo ClosureInfo
cl_info of
      LFReEntrant {}            -> Bool
False
      LambdaFormInfo
LFLetNoEscape             -> Bool
False
      LFThunk TopLevelFlag
_ Bool
_no_fvs Bool
upd StandardFormInfo
_ Bool
_ -> Bool
upd   -- See Note [Black-holing non-updatable thunks]
      LambdaFormInfo
_other -> String -> Bool
forall a. String -> a
panic String
"blackHoleOnEntry"

{- Note [Black-holing non-updatable thunks]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We must not black-hole non-updatable (single-entry) thunks otherwise
we run into issues like #10414. Specifically:

  * There is no reason to black-hole a non-updatable thunk: it should
    not be competed for by multiple threads

  * It could, conceivably, cause a space leak if we don't black-hole
    it, if there was a live but never-followed pointer pointing to it.
    Let's hope that doesn't happen.

  * It is dangerous to black-hole a non-updatable thunk because
     - is not updated (of course)
     - hence, if it is black-holed and another thread tries to evaluate
       it, that thread will block forever
    This actually happened in #10414.  So we do not black-hole
    non-updatable thunks.

  * How could two threads evaluate the same non-updatable (single-entry)
    thunk?  See Reid Barton's example below.

  * Only eager blackholing could possibly black-hole a non-updatable
    thunk, because lazy black-holing only affects thunks with an
    update frame on the stack.

Here is and example due to Reid Barton (#10414):
    x = \u []  concat [[1], []]
with the following definitions,

    concat x = case x of
        []       -> []
        (:) x xs -> (++) x (concat xs)

    (++) xs ys = case xs of
        []         -> ys
        (:) x rest -> (:) x ((++) rest ys)

Where we use the syntax @\u []@ to denote an updatable thunk and @\s []@ to
denote a single-entry (i.e. non-updatable) thunk. After a thread evaluates @x@
to WHNF and calls @(++)@ the heap will contain the following thunks,

    x = 1 : y
    y = \u []  (++) [] z
    z = \s []  concat []

Now that the stage is set, consider the follow evaluations by two racing threads
A and B,

  1. Both threads enter @y@ before either is able to replace it with an
     indirection

  2. Thread A does the case analysis in @(++)@ and consequently enters @z@,
     replacing it with a black-hole

  3. At some later point thread B does the same case analysis and also attempts
     to enter @z@. However, it finds that it has been replaced with a black-hole
     so it blocks.

  4. Thread A eventually finishes evaluating @z@ (to @[]@) and updates @y@
     accordingly. It does *not* update @z@, however, as it is single-entry. This
     leaves Thread B blocked forever on a black-hole which will never be
     updated.

To avoid this sort of condition we never black-hole non-updatable thunks.
-}

isStaticClosure :: ClosureInfo -> Bool
isStaticClosure :: ClosureInfo -> Bool
isStaticClosure ClosureInfo
cl_info = SMRep -> Bool
isStaticRep (ClosureInfo -> SMRep
closureSMRep ClosureInfo
cl_info)

closureUpdReqd :: ClosureInfo -> Bool
closureUpdReqd :: ClosureInfo -> Bool
closureUpdReqd ClosureInfo{ closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureLFInfo = LambdaFormInfo
lf_info } = LambdaFormInfo -> Bool
lfUpdatable LambdaFormInfo
lf_info

lfUpdatable :: LambdaFormInfo -> Bool
lfUpdatable :: LambdaFormInfo -> Bool
lfUpdatable (LFThunk TopLevelFlag
_ Bool
_ Bool
upd StandardFormInfo
_ Bool
_)  = Bool
upd
lfUpdatable LambdaFormInfo
_ = Bool
False

closureReEntrant :: ClosureInfo -> Bool
closureReEntrant :: ClosureInfo -> Bool
closureReEntrant (ClosureInfo { closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureLFInfo = LFReEntrant {} }) = Bool
True
closureReEntrant ClosureInfo
_ = Bool
False

closureFunInfo :: ClosureInfo -> Maybe (RepArity, ArgDescr)
closureFunInfo :: ClosureInfo -> Maybe (Int, ArgDescr)
closureFunInfo (ClosureInfo { closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureLFInfo = LambdaFormInfo
lf_info }) = LambdaFormInfo -> Maybe (Int, ArgDescr)
lfFunInfo LambdaFormInfo
lf_info

lfFunInfo :: LambdaFormInfo ->  Maybe (RepArity, ArgDescr)
lfFunInfo :: LambdaFormInfo -> Maybe (Int, ArgDescr)
lfFunInfo (LFReEntrant TopLevelFlag
_ Int
arity Bool
_ ArgDescr
arg_desc)  = (Int, ArgDescr) -> Maybe (Int, ArgDescr)
forall a. a -> Maybe a
Just (Int
arity, ArgDescr
arg_desc)
lfFunInfo LambdaFormInfo
_                                 = Maybe (Int, ArgDescr)
forall a. Maybe a
Nothing

funTag :: Platform -> ClosureInfo -> DynTag
funTag :: Platform -> ClosureInfo -> Int
funTag Platform
platform (ClosureInfo { closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureLFInfo = LambdaFormInfo
lf_info })
    = Platform -> LambdaFormInfo -> Int
lfDynTag Platform
platform LambdaFormInfo
lf_info

isToplevClosure :: ClosureInfo -> Bool
isToplevClosure :: ClosureInfo -> Bool
isToplevClosure (ClosureInfo { closureLFInfo :: ClosureInfo -> LambdaFormInfo
closureLFInfo = LambdaFormInfo
lf_info })
  = case LambdaFormInfo
lf_info of
      LFReEntrant TopLevelFlag
TopLevel Int
_ Bool
_ ArgDescr
_ -> Bool
True
      LFThunk TopLevelFlag
TopLevel Bool
_ Bool
_ StandardFormInfo
_ Bool
_   -> Bool
True
      LambdaFormInfo
_other                     -> Bool
False

--------------------------------------
--   Label generation
--------------------------------------

staticClosureLabel :: Platform -> ClosureInfo -> CLabel
staticClosureLabel :: Platform -> ClosureInfo -> CLabel
staticClosureLabel Platform
platform = Platform -> CLabel -> CLabel
toClosureLbl Platform
platform (CLabel -> CLabel)
-> (ClosureInfo -> CLabel) -> ClosureInfo -> CLabel
forall b c a. (b -> c) -> (a -> b) -> a -> c
.  ClosureInfo -> CLabel
closureInfoLabel

closureSlowEntryLabel :: Platform -> ClosureInfo -> CLabel
closureSlowEntryLabel :: Platform -> ClosureInfo -> CLabel
closureSlowEntryLabel Platform
platform = Platform -> CLabel -> CLabel
toSlowEntryLbl Platform
platform (CLabel -> CLabel)
-> (ClosureInfo -> CLabel) -> ClosureInfo -> CLabel
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ClosureInfo -> CLabel
closureInfoLabel

closureLocalEntryLabel :: Platform -> ClosureInfo -> CLabel
closureLocalEntryLabel :: Platform -> ClosureInfo -> CLabel
closureLocalEntryLabel Platform
platform
  | Platform -> Bool
platformTablesNextToCode Platform
platform = Platform -> CLabel -> CLabel
toInfoLbl  Platform
platform (CLabel -> CLabel)
-> (ClosureInfo -> CLabel) -> ClosureInfo -> CLabel
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ClosureInfo -> CLabel
closureInfoLabel
  | Bool
otherwise                         = Platform -> CLabel -> CLabel
toEntryLbl Platform
platform (CLabel -> CLabel)
-> (ClosureInfo -> CLabel) -> ClosureInfo -> CLabel
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ClosureInfo -> CLabel
closureInfoLabel

-- | Get the info table label for a *thunk*.
mkClosureInfoTableLabel :: Platform -> Id -> LambdaFormInfo -> CLabel
mkClosureInfoTableLabel :: Platform -> Id -> LambdaFormInfo -> CLabel
mkClosureInfoTableLabel Platform
platform Id
id LambdaFormInfo
lf_info
  = case LambdaFormInfo
lf_info of
        LFThunk TopLevelFlag
_ Bool
_ Bool
upd_flag (SelectorThunk Int
offset) Bool
_
                      -> Platform -> Bool -> Int -> CLabel
mkSelectorInfoLabel Platform
platform Bool
upd_flag Int
offset

        LFThunk TopLevelFlag
_ Bool
_ Bool
upd_flag (ApThunk Int
arity) Bool
_
                      -> Platform -> Bool -> Int -> CLabel
mkApInfoTableLabel Platform
platform Bool
upd_flag Int
arity

        LFThunk{}     -> Name -> CafInfo -> CLabel
mkInfoTableLabel Name
name CafInfo
cafs
        LFReEntrant{} -> Name -> CafInfo -> CLabel
mkInfoTableLabel Name
name CafInfo
cafs
        LambdaFormInfo
_other        -> String -> CLabel
forall a. String -> a
panic String
"closureInfoTableLabel"

  where
    name :: Name
name = Id -> Name
idName Id
id

    cafs :: CafInfo
cafs     = Id -> CafInfo
idCafInfo Id
id

-- | thunkEntryLabel is a local help function, not exported.  It's used from
-- getCallMethod.
thunkEntryLabel :: Platform -> Name -> CafInfo -> StandardFormInfo -> Bool -> CLabel
thunkEntryLabel :: Platform -> Name -> CafInfo -> StandardFormInfo -> Bool -> CLabel
thunkEntryLabel Platform
platform Name
thunk_id CafInfo
caf_info StandardFormInfo
sfi Bool
upd_flag = case StandardFormInfo
sfi of
   ApThunk Int
arity        -> Platform -> Bool -> Int -> CLabel
enterApLabel       Platform
platform Bool
upd_flag Int
arity
   SelectorThunk Int
offset -> Platform -> Bool -> Int -> CLabel
enterSelectorLabel Platform
platform Bool
upd_flag Int
offset
   StandardFormInfo
_                    -> Platform -> Name -> CafInfo -> CLabel
enterIdLabel       Platform
platform Name
thunk_id CafInfo
caf_info

enterApLabel :: Platform -> Bool -> Arity -> CLabel
enterApLabel :: Platform -> Bool -> Int -> CLabel
enterApLabel Platform
platform Bool
is_updatable Int
arity
  | Platform -> Bool
platformTablesNextToCode Platform
platform = Platform -> Bool -> Int -> CLabel
mkApInfoTableLabel Platform
platform Bool
is_updatable Int
arity
  | Bool
otherwise                         = Platform -> Bool -> Int -> CLabel
mkApEntryLabel     Platform
platform Bool
is_updatable Int
arity

enterSelectorLabel :: Platform -> Bool -> WordOff -> CLabel
enterSelectorLabel :: Platform -> Bool -> Int -> CLabel
enterSelectorLabel Platform
platform Bool
upd_flag Int
offset
  | Platform -> Bool
platformTablesNextToCode Platform
platform = Platform -> Bool -> Int -> CLabel
mkSelectorInfoLabel  Platform
platform Bool
upd_flag Int
offset
  | Bool
otherwise                         = Platform -> Bool -> Int -> CLabel
mkSelectorEntryLabel Platform
platform Bool
upd_flag Int
offset

enterIdLabel :: Platform -> Name -> CafInfo -> CLabel
enterIdLabel :: Platform -> Name -> CafInfo -> CLabel
enterIdLabel Platform
platform Name
id CafInfo
c
  | Platform -> Bool
platformTablesNextToCode Platform
platform = Name -> CafInfo -> CLabel
mkInfoTableLabel Name
id CafInfo
c
  | Bool
otherwise                         = Name -> CafInfo -> CLabel
mkEntryLabel Name
id CafInfo
c


--------------------------------------
--   Profiling
--------------------------------------

-- Profiling requires two pieces of information to be determined for
-- each closure's info table --- description and type.

-- The description is stored directly in the @CClosureInfoTable@ when the
-- info table is built.

-- The type is determined from the type information stored with the @Id@
-- in the closure info using @closureTypeDescr@.

mkProfilingInfo :: Profile -> Id -> String -> ProfilingInfo
mkProfilingInfo :: Profile -> Id -> String -> ProfilingInfo
mkProfilingInfo Profile
profile Id
id String
val_descr
  | Bool -> Bool
not (Profile -> Bool
profileIsProfiling Profile
profile) = ProfilingInfo
NoProfilingInfo
  | Bool
otherwise                        = ConstrDescription -> ConstrDescription -> ProfilingInfo
ProfilingInfo ConstrDescription
ty_descr_w8 (String -> ConstrDescription
BS8.pack String
val_descr)
  where
    ty_descr_w8 :: ConstrDescription
ty_descr_w8  = String -> ConstrDescription
BS8.pack (Type -> String
getTyDescription (Id -> Type
idType Id
id))

getTyDescription :: Type -> String
getTyDescription :: Type -> String
getTyDescription Type
ty
  = case (Type -> ([Id], ThetaType, Type)
tcSplitSigmaTy Type
ty) of { ([Id]
_, ThetaType
_, Type
tau_ty) ->
    case Type
tau_ty of
      TyVarTy Id
_              -> String
"*"
      AppTy Type
fun Type
_            -> Type -> String
getTyDescription Type
fun
      TyConApp TyCon
tycon ThetaType
_       -> TyCon -> String
forall a. NamedThing a => a -> String
getOccString TyCon
tycon
      FunTy {}              -> Char
'-' Char -> ShowS
forall a. a -> [a] -> [a]
: Type -> String
fun_result Type
tau_ty
      ForAllTy TyCoVarBinder
_  Type
ty         -> Type -> String
getTyDescription Type
ty
      LitTy TyLit
n                -> TyLit -> String
getTyLitDescription TyLit
n
      CastTy Type
ty Coercion
_            -> Type -> String
getTyDescription Type
ty
      CoercionTy Coercion
co          -> String -> SDoc -> String
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"getTyDescription" (Coercion -> SDoc
forall a. Outputable a => a -> SDoc
ppr Coercion
co)
    }
  where
    fun_result :: Type -> String
fun_result (FunTy { ft_res :: Type -> Type
ft_res = Type
res }) = Char
'>' Char -> ShowS
forall a. a -> [a] -> [a]
: Type -> String
fun_result Type
res
    fun_result Type
other                    = Type -> String
getTyDescription Type
other

getTyLitDescription :: TyLit -> String
getTyLitDescription :: TyLit -> String
getTyLitDescription TyLit
l =
  case TyLit
l of
    NumTyLit Integer
n -> Integer -> String
forall a. Show a => a -> String
show Integer
n
    StrTyLit FastString
n -> FastString -> String
forall a. Show a => a -> String
show FastString
n
    CharTyLit Char
n -> Char -> String
forall a. Show a => a -> String
show Char
n

--------------------------------------
--   CmmInfoTable-related things
--------------------------------------

mkDataConInfoTable :: Profile -> DataCon -> ConInfoTableLocation -> Bool -> Int -> Int -> CmmInfoTable
mkDataConInfoTable :: Profile
-> DataCon
-> ConInfoTableLocation
-> Bool
-> Int
-> Int
-> CmmInfoTable
mkDataConInfoTable Profile
profile DataCon
data_con ConInfoTableLocation
mn Bool
is_static Int
ptr_wds Int
nonptr_wds
 = CmmInfoTable { cit_lbl :: CLabel
cit_lbl  = CLabel
info_lbl
                , cit_rep :: SMRep
cit_rep  = SMRep
sm_rep
                , cit_prof :: ProfilingInfo
cit_prof = ProfilingInfo
prof
                , cit_srt :: Maybe CLabel
cit_srt  = Maybe CLabel
forall a. Maybe a
Nothing
                , cit_clo :: Maybe (Id, CostCentreStack)
cit_clo  = Maybe (Id, CostCentreStack)
forall a. Maybe a
Nothing }
 where
   name :: Name
name = DataCon -> Name
dataConName DataCon
data_con
   info_lbl :: CLabel
info_lbl = Name -> ConInfoTableLocation -> CLabel
mkConInfoTableLabel Name
name ConInfoTableLocation
mn -- NoCAFRefs
   sm_rep :: SMRep
sm_rep = Profile -> Bool -> Int -> Int -> ClosureTypeInfo -> SMRep
mkHeapRep Profile
profile Bool
is_static Int
ptr_wds Int
nonptr_wds ClosureTypeInfo
cl_type
   cl_type :: ClosureTypeInfo
cl_type = Int -> ConstrDescription -> ClosureTypeInfo
Constr (DataCon -> Int
dataConTagZ DataCon
data_con) (DataCon -> ConstrDescription
dataConIdentity DataCon
data_con)
                  -- We keep the *zero-indexed* tag in the srt_len field
                  -- of the info table of a data constructor.

   prof :: ProfilingInfo
prof | Bool -> Bool
not (Profile -> Bool
profileIsProfiling Profile
profile) = ProfilingInfo
NoProfilingInfo
        | Bool
otherwise                        = ConstrDescription -> ConstrDescription -> ProfilingInfo
ProfilingInfo ConstrDescription
ty_descr ConstrDescription
val_descr

   ty_descr :: ConstrDescription
ty_descr  = String -> ConstrDescription
BS8.pack (String -> ConstrDescription) -> String -> ConstrDescription
forall a b. (a -> b) -> a -> b
$ OccName -> String
occNameString (OccName -> String) -> OccName -> String
forall a b. (a -> b) -> a -> b
$ TyCon -> OccName
forall a. NamedThing a => a -> OccName
getOccName (TyCon -> OccName) -> TyCon -> OccName
forall a b. (a -> b) -> a -> b
$ DataCon -> TyCon
dataConTyCon DataCon
data_con
   val_descr :: ConstrDescription
val_descr = String -> ConstrDescription
BS8.pack (String -> ConstrDescription) -> String -> ConstrDescription
forall a b. (a -> b) -> a -> b
$ OccName -> String
occNameString (OccName -> String) -> OccName -> String
forall a b. (a -> b) -> a -> b
$ DataCon -> OccName
forall a. NamedThing a => a -> OccName
getOccName DataCon
data_con

-- We need a black-hole closure info to pass to @allocDynClosure@ when we
-- want to allocate the black hole on entry to a CAF.

cafBlackHoleInfoTable :: CmmInfoTable
cafBlackHoleInfoTable :: CmmInfoTable
cafBlackHoleInfoTable
  = CmmInfoTable { cit_lbl :: CLabel
cit_lbl  = CLabel
mkCAFBlackHoleInfoTableLabel
                 , cit_rep :: SMRep
cit_rep  = SMRep
blackHoleRep
                 , cit_prof :: ProfilingInfo
cit_prof = ProfilingInfo
NoProfilingInfo
                 , cit_srt :: Maybe CLabel
cit_srt  = Maybe CLabel
forall a. Maybe a
Nothing
                 , cit_clo :: Maybe (Id, CostCentreStack)
cit_clo  = Maybe (Id, CostCentreStack)
forall a. Maybe a
Nothing }

indStaticInfoTable :: CmmInfoTable
indStaticInfoTable :: CmmInfoTable
indStaticInfoTable
  = CmmInfoTable { cit_lbl :: CLabel
cit_lbl  = CLabel
mkIndStaticInfoLabel
                 , cit_rep :: SMRep
cit_rep  = SMRep
indStaticRep
                 , cit_prof :: ProfilingInfo
cit_prof = ProfilingInfo
NoProfilingInfo
                 , cit_srt :: Maybe CLabel
cit_srt  = Maybe CLabel
forall a. Maybe a
Nothing
                 , cit_clo :: Maybe (Id, CostCentreStack)
cit_clo  = Maybe (Id, CostCentreStack)
forall a. Maybe a
Nothing }

staticClosureNeedsLink :: Bool -> CmmInfoTable -> Bool
-- A static closure needs a link field to aid the GC when traversing
-- the static closure graph.  But it only needs such a field if either
--        a) it has an SRT
--        b) it's a constructor with one or more pointer fields
-- In case (b), the constructor's fields themselves play the role
-- of the SRT.
staticClosureNeedsLink :: Bool -> CmmInfoTable -> Bool
staticClosureNeedsLink Bool
has_srt CmmInfoTable{ cit_rep :: CmmInfoTable -> SMRep
cit_rep = SMRep
smrep }
  | SMRep -> Bool
isConRep SMRep
smrep         = Bool -> Bool
not (SMRep -> Bool
isStaticNoCafCon SMRep
smrep)
  | Bool
otherwise              = Bool
has_srt