{-# LANGUAGE CPP #-}
{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE TypeFamilies #-}

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

--------------------------------------------------------------
-- Converting Core to STG Syntax
--------------------------------------------------------------

-- And, as we have the info in hand, we may convert some lets to
-- let-no-escapes.

module GHC.CoreToStg ( coreToStg ) where

#include "HsVersions.h"

import GHC.Prelude

import GHC.Core
import GHC.Core.Utils   ( exprType, findDefault, isJoinBind
                        , exprIsTickedString_maybe )
import GHC.Core.Opt.Arity   ( manifestArity )
import GHC.Stg.Syntax
import GHC.Stg.Debug

import GHC.Core.Type
import GHC.Types.RepType
import GHC.Core.TyCon
import GHC.Types.Id.Make ( coercionTokenId )
import GHC.Types.Id
import GHC.Types.Id.Info
import GHC.Core.DataCon
import GHC.Types.CostCentre
import GHC.Types.Tickish
import GHC.Types.Var.Env
import GHC.Unit.Module
import GHC.Types.Name   ( isExternalName, nameModule_maybe )
import GHC.Types.Basic  ( Arity )
import GHC.Builtin.Types ( unboxedUnitDataCon, unitDataConId )
import GHC.Types.Literal
import GHC.Utils.Outputable
import GHC.Utils.Monad
import GHC.Data.FastString
import GHC.Utils.Misc
import GHC.Utils.Panic
import GHC.Driver.Session
import GHC.Platform.Ways
import GHC.Driver.Ppr
import GHC.Types.ForeignCall
import GHC.Types.IPE
import GHC.Types.Demand    ( isUsedOnceDmd )
import GHC.Builtin.PrimOps ( PrimCall(..) )
import GHC.Types.SrcLoc    ( mkGeneralSrcSpan )

import Control.Monad (ap)
import Data.Maybe (fromMaybe)
import Data.Tuple (swap)
import qualified Data.Set as Set

-- Note [Live vs free]
-- ~~~~~~~~~~~~~~~~~~~
--
-- The two are not the same. Liveness is an operational property rather
-- than a semantic one. A variable is live at a particular execution
-- point if it can be referred to directly again. In particular, a dead
-- variable's stack slot (if it has one):
--
--           - should be stubbed to avoid space leaks, and
--           - may be reused for something else.
--
-- There ought to be a better way to say this. Here are some examples:
--
--         let v = [q] \[x] -> e
--         in
--         ...v...  (but no q's)
--
-- Just after the `in', v is live, but q is dead. If the whole of that
-- let expression was enclosed in a case expression, thus:
--
--         case (let v = [q] \[x] -> e in ...v...) of
--                 alts[...q...]
--
-- (ie `alts' mention `q'), then `q' is live even after the `in'; because
-- we'll return later to the `alts' and need it.
--
-- Let-no-escapes make this a bit more interesting:
--
--         let-no-escape v = [q] \ [x] -> e
--         in
--         ...v...
--
-- Here, `q' is still live at the `in', because `v' is represented not by
-- a closure but by the current stack state.  In other words, if `v' is
-- live then so is `q'. Furthermore, if `e' mentions an enclosing
-- let-no-escaped variable, then its free variables are also live if `v' is.

-- Note [What are these SRTs all about?]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- Consider the Core program,
--
--     fibs = go 1 1
--       where go a b = let c = a + c
--                      in c : go b c
--     add x = map (\y -> x*y) fibs
--
-- In this case we have a CAF, 'fibs', which is quite large after evaluation and
-- has only one possible user, 'add'. Consequently, we want to ensure that when
-- all references to 'add' die we can garbage collect any bit of 'fibs' that we
-- have evaluated.
--
-- However, how do we know whether there are any references to 'fibs' still
-- around? Afterall, the only reference to it is buried in the code generated
-- for 'add'. The answer is that we record the CAFs referred to by a definition
-- in its info table, namely a part of it known as the Static Reference Table
-- (SRT).
--
-- Since SRTs are so common, we use a special compact encoding for them in: we
-- produce one table containing a list of CAFs in a module and then include a
-- bitmap in each info table describing which entries of this table the closure
-- references.
--
-- See also: commentary/rts/storage/gc/CAFs on the GHC Wiki.

-- Note [What is a non-escaping let]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- NB: Nowadays this is recognized by the occurrence analyser by turning a
-- "non-escaping let" into a join point. The following is then an operational
-- account of join points.
--
-- Consider:
--
--     let x = fvs \ args -> e
--     in
--         if ... then x else
--            if ... then x else ...
--
-- `x' is used twice (so we probably can't unfold it), but when it is
-- entered, the stack is deeper than it was when the definition of `x'
-- happened.  Specifically, if instead of allocating a closure for `x',
-- we saved all `x's fvs on the stack, and remembered the stack depth at
-- that moment, then whenever we enter `x' we can simply set the stack
-- pointer(s) to these remembered (compile-time-fixed) values, and jump
-- to the code for `x'.
--
-- All of this is provided x is:
--   1. non-updatable;
--   2. guaranteed to be entered before the stack retreats -- ie x is not
--      buried in a heap-allocated closure, or passed as an argument to
--      something;
--   3. all the enters have exactly the right number of arguments,
--      no more no less;
--   4. all the enters are tail calls; that is, they return to the
--      caller enclosing the definition of `x'.
--
-- Under these circumstances we say that `x' is non-escaping.
--
-- An example of when (4) does not hold:
--
--     let x = ...
--     in case x of ...alts...
--
-- Here, `x' is certainly entered only when the stack is deeper than when
-- `x' is defined, but here it must return to ...alts... So we can't just
-- adjust the stack down to `x''s recalled points, because that would lost
-- alts' context.
--
-- Things can get a little more complicated.  Consider:
--
--     let y = ...
--     in let x = fvs \ args -> ...y...
--     in ...x...
--
-- Now, if `x' is used in a non-escaping way in ...x..., and `y' is used in a
-- non-escaping way in ...y..., then `y' is non-escaping.
--
-- `x' can even be recursive!  Eg:
--
--     letrec x = [y] \ [v] -> if v then x True else ...
--     in
--         ...(x b)...

-- Note [Cost-centre initialization plan]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- Previously `coreToStg` was initializing cost-centre stack fields as `noCCS`,
-- and the fields were then fixed by a separate pass `stgMassageForProfiling`.
-- We now initialize these correctly. The initialization works like this:
--
--   - For non-top level bindings always use `currentCCS`.
--
--   - For top-level bindings, check if the binding is a CAF
--
--     - CAF:      If -fcaf-all is enabled, create a new CAF just for this CAF
--                 and use it. Note that these new cost centres need to be
--                 collected to be able to generate cost centre initialization
--                 code, so `coreToTopStgRhs` now returns `CollectedCCs`.
--
--                 If -fcaf-all is not enabled, use "all CAFs" cost centre.
--
--     - Non-CAF:  Top-level (static) data is not counted in heap profiles; nor
--                 do we set CCCS from it; so we just slam in
--                 dontCareCostCentre.

-- Note [Coercion tokens]
-- ~~~~~~~~~~~~~~~~~~~~~~
-- In coreToStgArgs, we drop type arguments completely, but we replace
-- coercions with a special coercionToken# placeholder. Why? Consider:
--
--   f :: forall a. Int ~# Bool -> a
--   f = /\a. \(co :: Int ~# Bool) -> error "impossible"
--
-- If we erased the coercion argument completely, we’d end up with just
-- f = error "impossible", but then f `seq` () would be ⊥!
--
-- This is an artificial example, but back in the day we *did* treat
-- coercion lambdas like type lambdas, and we had bug reports as a
-- result. So now we treat coercion lambdas like value lambdas, but we
-- treat coercions themselves as zero-width arguments — coercionToken#
-- has representation VoidRep — which gets the best of both worlds.
--
-- (For the gory details, see also the (unpublished) paper, “Practical
-- aspects of evidence-based compilation in System FC.”)

-- --------------------------------------------------------------
-- Setting variable info: top-level, binds, RHSs
-- --------------------------------------------------------------


coreToStg :: DynFlags -> Module -> ModLocation -> CoreProgram
          -> ([StgTopBinding], InfoTableProvMap, CollectedCCs)
coreToStg :: DynFlags
-> Module
-> ModLocation
-> CoreProgram
-> ([StgTopBinding], InfoTableProvMap, CollectedCCs)
coreToStg DynFlags
dflags Module
this_mod ModLocation
ml CoreProgram
pgm
  = ([StgTopBinding]
pgm'', InfoTableProvMap
denv, CollectedCCs
final_ccs)
  where
    (IdEnv HowBound
_, ([CostCentre]
local_ccs, [CostCentreStack]
local_cc_stacks), [StgTopBinding]
pgm')
      = DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreProgram
-> (IdEnv HowBound, CollectedCCs, [StgTopBinding])
coreTopBindsToStg DynFlags
dflags Module
this_mod forall a. VarEnv a
emptyVarEnv CollectedCCs
emptyCollectedCCs CoreProgram
pgm

    -- See Note [Mapping Info Tables to Source Positions]
    (![StgTopBinding]
pgm'', !InfoTableProvMap
denv) =
        if GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_InfoTableMap DynFlags
dflags
          then DynFlags
-> ModLocation
-> [StgTopBinding]
-> ([StgTopBinding], InfoTableProvMap)
collectDebugInformation DynFlags
dflags ModLocation
ml [StgTopBinding]
pgm'
          else ([StgTopBinding]
pgm', InfoTableProvMap
emptyInfoTableProvMap)

    prof :: Bool
prof = Way
WayProf forall a. Ord a => a -> Set a -> Bool
`Set.member` DynFlags -> Ways
ways DynFlags
dflags

    final_ccs :: CollectedCCs
final_ccs
      | Bool
prof Bool -> Bool -> Bool
&& GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_AutoSccsOnIndividualCafs DynFlags
dflags
      = ([CostCentre]
local_ccs,[CostCentreStack]
local_cc_stacks)  -- don't need "all CAFs" CC
      | Bool
prof
      = (CostCentre
all_cafs_ccforall a. a -> [a] -> [a]
:[CostCentre]
local_ccs, CostCentreStack
all_cafs_ccsforall a. a -> [a] -> [a]
:[CostCentreStack]
local_cc_stacks)
      | Bool
otherwise
      = CollectedCCs
emptyCollectedCCs

    (CostCentre
all_cafs_cc, CostCentreStack
all_cafs_ccs) = Module -> (CostCentre, CostCentreStack)
getAllCAFsCC Module
this_mod

coreTopBindsToStg
    :: DynFlags
    -> Module
    -> IdEnv HowBound           -- environment for the bindings
    -> CollectedCCs
    -> CoreProgram
    -> (IdEnv HowBound, CollectedCCs, [StgTopBinding])

coreTopBindsToStg :: DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreProgram
-> (IdEnv HowBound, CollectedCCs, [StgTopBinding])
coreTopBindsToStg DynFlags
_      Module
_        IdEnv HowBound
env CollectedCCs
ccs []
  = (IdEnv HowBound
env, CollectedCCs
ccs, [])
coreTopBindsToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env CollectedCCs
ccs (CoreBind
b:CoreProgram
bs)
  | NonRec Var
_ Expr Var
rhs <- CoreBind
b, forall b. Expr b -> Bool
isTyCoArg Expr Var
rhs
  = DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreProgram
-> (IdEnv HowBound, CollectedCCs, [StgTopBinding])
coreTopBindsToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env1 CollectedCCs
ccs1 CoreProgram
bs
  | Bool
otherwise
  = (IdEnv HowBound
env2, CollectedCCs
ccs2, StgTopBinding
b'forall a. a -> [a] -> [a]
:[StgTopBinding]
bs')
  where
    (IdEnv HowBound
env1, CollectedCCs
ccs1, StgTopBinding
b' ) = DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreBind
-> (IdEnv HowBound, CollectedCCs, StgTopBinding)
coreTopBindToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env CollectedCCs
ccs CoreBind
b
    (IdEnv HowBound
env2, CollectedCCs
ccs2, [StgTopBinding]
bs') = DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreProgram
-> (IdEnv HowBound, CollectedCCs, [StgTopBinding])
coreTopBindsToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env1 CollectedCCs
ccs1 CoreProgram
bs

coreTopBindToStg
        :: DynFlags
        -> Module
        -> IdEnv HowBound
        -> CollectedCCs
        -> CoreBind
        -> (IdEnv HowBound, CollectedCCs, StgTopBinding)

coreTopBindToStg :: DynFlags
-> Module
-> IdEnv HowBound
-> CollectedCCs
-> CoreBind
-> (IdEnv HowBound, CollectedCCs, StgTopBinding)
coreTopBindToStg DynFlags
_ Module
_ IdEnv HowBound
env CollectedCCs
ccs (NonRec Var
id Expr Var
e)
  | Just ByteString
str <- Expr Var -> Maybe ByteString
exprIsTickedString_maybe Expr Var
e
  -- top-level string literal
  -- See Note [Core top-level string literals] in GHC.Core
  = let
        env' :: IdEnv HowBound
env' = forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv IdEnv HowBound
env Var
id HowBound
how_bound
        how_bound :: HowBound
how_bound = LetInfo -> JoinArity -> HowBound
LetBound LetInfo
TopLet JoinArity
0
    in (IdEnv HowBound
env', CollectedCCs
ccs, forall (pass :: StgPass).
Var -> ByteString -> GenStgTopBinding pass
StgTopStringLit Var
id ByteString
str)

coreTopBindToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env CollectedCCs
ccs (NonRec Var
id Expr Var
rhs)
  = let
        env' :: IdEnv HowBound
env'      = forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv IdEnv HowBound
env Var
id HowBound
how_bound
        how_bound :: HowBound
how_bound = LetInfo -> JoinArity -> HowBound
LetBound LetInfo
TopLet forall a b. (a -> b) -> a -> b
$! Expr Var -> JoinArity
manifestArity Expr Var
rhs

        (StgRhs
stg_rhs, CollectedCCs
ccs') =
            forall a. DynFlags -> IdEnv HowBound -> CtsM a -> a
initCts DynFlags
dflags IdEnv HowBound
env forall a b. (a -> b) -> a -> b
$
              DynFlags
-> CollectedCCs
-> Module
-> (Var, Expr Var)
-> CtsM (StgRhs, CollectedCCs)
coreToTopStgRhs DynFlags
dflags CollectedCCs
ccs Module
this_mod (Var
id,Expr Var
rhs)

        bind :: StgTopBinding
bind = forall (pass :: StgPass).
GenStgBinding pass -> GenStgTopBinding pass
StgTopLifted forall a b. (a -> b) -> a -> b
$ forall (pass :: StgPass).
BinderP pass -> GenStgRhs pass -> GenStgBinding pass
StgNonRec Var
id StgRhs
stg_rhs
    in
      -- NB: previously the assertion printed 'rhs' and 'bind'
      --     as well as 'id', but that led to a black hole
      --     where printing the assertion error tripped the
      --     assertion again!
    (IdEnv HowBound
env', CollectedCCs
ccs', StgTopBinding
bind)

coreTopBindToStg DynFlags
dflags Module
this_mod IdEnv HowBound
env CollectedCCs
ccs (Rec [(Var, Expr Var)]
pairs)
  = ASSERT( not (null pairs) )
    let
        binders :: [Var]
binders = forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> a
fst [(Var, Expr Var)]
pairs

        extra_env' :: [(Var, HowBound)]
extra_env' = [ (Var
b, LetInfo -> JoinArity -> HowBound
LetBound LetInfo
TopLet forall a b. (a -> b) -> a -> b
$! Expr Var -> JoinArity
manifestArity Expr Var
rhs)
                     | (Var
b, Expr Var
rhs) <- [(Var, Expr Var)]
pairs ]
        env' :: IdEnv HowBound
env' = forall a. VarEnv a -> [(Var, a)] -> VarEnv a
extendVarEnvList IdEnv HowBound
env [(Var, HowBound)]
extra_env'

        -- generate StgTopBindings and CAF cost centres created for CAFs
        (CollectedCCs
ccs', [StgRhs]
stg_rhss)
          = forall a. DynFlags -> IdEnv HowBound -> CtsM a -> a
initCts DynFlags
dflags IdEnv HowBound
env' forall a b. (a -> b) -> a -> b
$
              forall (m :: * -> *) acc x y.
Monad m =>
(acc -> x -> m (acc, y)) -> acc -> [x] -> m (acc, [y])
mapAccumLM (\CollectedCCs
ccs (Var, Expr Var)
rhs -> forall a b. (a, b) -> (b, a)
swap forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> DynFlags
-> CollectedCCs
-> Module
-> (Var, Expr Var)
-> CtsM (StgRhs, CollectedCCs)
coreToTopStgRhs DynFlags
dflags CollectedCCs
ccs Module
this_mod (Var, Expr Var)
rhs)
                         CollectedCCs
ccs
                         [(Var, Expr Var)]
pairs
        bind :: StgTopBinding
bind = forall (pass :: StgPass).
GenStgBinding pass -> GenStgTopBinding pass
StgTopLifted forall a b. (a -> b) -> a -> b
$ forall (pass :: StgPass).
[(BinderP pass, GenStgRhs pass)] -> GenStgBinding pass
StgRec (forall a b. [a] -> [b] -> [(a, b)]
zip [Var]
binders [StgRhs]
stg_rhss)
    in
    (IdEnv HowBound
env', CollectedCCs
ccs', StgTopBinding
bind)

coreToTopStgRhs
        :: DynFlags
        -> CollectedCCs
        -> Module
        -> (Id,CoreExpr)
        -> CtsM (StgRhs, CollectedCCs)

coreToTopStgRhs :: DynFlags
-> CollectedCCs
-> Module
-> (Var, Expr Var)
-> CtsM (StgRhs, CollectedCCs)
coreToTopStgRhs DynFlags
dflags CollectedCCs
ccs Module
this_mod (Var
bndr, Expr Var
rhs)
  = do { PreStgRhs
new_rhs <- Expr Var -> CtsM PreStgRhs
coreToPreStgRhs Expr Var
rhs

       ; let (StgRhs
stg_rhs, CollectedCCs
ccs') =
               DynFlags
-> Module
-> CollectedCCs
-> Var
-> PreStgRhs
-> (StgRhs, CollectedCCs)
mkTopStgRhs DynFlags
dflags Module
this_mod CollectedCCs
ccs Var
bndr PreStgRhs
new_rhs
             stg_arity :: JoinArity
stg_arity =
               StgRhs -> JoinArity
stgRhsArity StgRhs
stg_rhs

       ; forall (m :: * -> *) a. Monad m => a -> m a
return (ASSERT2( arity_ok stg_arity, mk_arity_msg stg_arity) stg_rhs,
                 CollectedCCs
ccs') }
  where
        -- It's vital that the arity on a top-level Id matches
        -- the arity of the generated STG binding, else an importing
        -- module will use the wrong calling convention
        --      (#2844 was an example where this happened)
        -- NB1: we can't move the assertion further out without
        --      blocking the "knot" tied in coreTopBindsToStg
        -- NB2: the arity check is only needed for Ids with External
        --      Names, because they are externally visible.  The CorePrep
        --      pass introduces "sat" things with Local Names and does
        --      not bother to set their Arity info, so don't fail for those
    arity_ok :: JoinArity -> Bool
arity_ok JoinArity
stg_arity
       | Name -> Bool
isExternalName (Var -> Name
idName Var
bndr) = JoinArity
id_arity forall a. Eq a => a -> a -> Bool
== JoinArity
stg_arity
       | Bool
otherwise                    = Bool
True
    id_arity :: JoinArity
id_arity  = Var -> JoinArity
idArity Var
bndr
    mk_arity_msg :: JoinArity -> SDoc
mk_arity_msg JoinArity
stg_arity
        = [SDoc] -> SDoc
vcat [forall a. Outputable a => a -> SDoc
ppr Var
bndr,
                String -> SDoc
text String
"Id arity:" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr JoinArity
id_arity,
                String -> SDoc
text String
"STG arity:" SDoc -> SDoc -> SDoc
<+> forall a. Outputable a => a -> SDoc
ppr JoinArity
stg_arity]

-- ---------------------------------------------------------------------------
-- Expressions
-- ---------------------------------------------------------------------------

-- coreToStgExpr panics if the input expression is a value lambda. CorePrep
-- ensures that value lambdas only exist as the RHS of bindings, which we
-- handle with the function coreToPreStgRhs.

coreToStgExpr
        :: CoreExpr
        -> CtsM StgExpr

-- The second and third components can be derived in a simple bottom up pass, not
-- dependent on any decisions about which variables will be let-no-escaped or
-- not.  The first component, that is, the decorated expression, may then depend
-- on these components, but it in turn is not scrutinised as the basis for any
-- decisions.  Hence no black holes.

-- No LitInteger's or LitNatural's should be left by the time this is called.
-- CorePrep should have converted them all to a real core representation.
coreToStgExpr :: Expr Var -> CtsM StgExpr
coreToStgExpr (Lit (LitNumber LitNumType
LitNumInteger Integer
_)) = forall a. String -> a
panic String
"coreToStgExpr: LitInteger"
coreToStgExpr (Lit (LitNumber LitNumType
LitNumNatural Integer
_)) = forall a. String -> a
panic String
"coreToStgExpr: LitNatural"
coreToStgExpr (Lit Literal
l)      = forall (m :: * -> *) a. Monad m => a -> m a
return (forall (pass :: StgPass). Literal -> GenStgExpr pass
StgLit Literal
l)
coreToStgExpr (App (Lit Literal
lit) Expr Var
_some_boxed_type)
  | Literal -> Bool
isRubbishLit Literal
lit
  -- We lower 'LitRubbish' to @()@ here, which is much easier than doing it in
  -- a STG to Cmm pass. Doesn't matter whether it is lifted or unlifted
  = Expr Var -> CtsM StgExpr
coreToStgExpr (forall b. Var -> Expr b
Var Var
unitDataConId)
coreToStgExpr (Var Var
v) = Var -> [Expr Var] -> [CoreTickish] -> CtsM StgExpr
coreToStgApp Var
v [] []
coreToStgExpr (Coercion Coercion
_)
  -- See Note [Coercion tokens]
  = Var -> [Expr Var] -> [CoreTickish] -> CtsM StgExpr
coreToStgApp Var
coercionTokenId [] []

coreToStgExpr expr :: Expr Var
expr@(App Expr Var
_ Expr Var
_)
  = Var -> [Expr Var] -> [CoreTickish] -> CtsM StgExpr
coreToStgApp Var
f [Expr Var]
args [CoreTickish]
ticks
  where
    (Var
f, [Expr Var]
args, [CoreTickish]
ticks) = Expr Var -> (Var, [Expr Var], [CoreTickish])
myCollectArgs Expr Var
expr

coreToStgExpr expr :: Expr Var
expr@(Lam Var
_ Expr Var
_)
  = let
        ([Var]
args, Expr Var
body) = Expr Var -> ([Var], Expr Var)
myCollectBinders Expr Var
expr
    in
    case [Var] -> [Var]
filterStgBinders [Var]
args of

      [] -> Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
body

      [Var]
_ -> forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"coretoStgExpr" forall a b. (a -> b) -> a -> b
$
        String -> SDoc
text String
"Unexpected value lambda:" SDoc -> SDoc -> SDoc
$$ forall a. Outputable a => a -> SDoc
ppr Expr Var
expr

coreToStgExpr (Tick CoreTickish
tick Expr Var
expr)
  = do
       let !stg_tick :: StgTickish
stg_tick = Type -> CoreTickish -> StgTickish
coreToStgTick (Expr Var -> Type
exprType Expr Var
expr) CoreTickish
tick
       !StgExpr
expr2 <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
expr
       forall (m :: * -> *) a. Monad m => a -> m a
return (forall (pass :: StgPass).
StgTickish -> GenStgExpr pass -> GenStgExpr pass
StgTick StgTickish
stg_tick StgExpr
expr2)

coreToStgExpr (Cast Expr Var
expr Coercion
_)
  = Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
expr

-- Cases require a little more real work.

{-
coreToStgExpr (Case scrut _ _ [])
  = coreToStgExpr scrut
    -- See Note [Empty case alternatives] in GHC.Core If the case
    -- alternatives are empty, the scrutinee must diverge or raise an
    -- exception, so we can just dive into it.
    --
    -- Of course this may seg-fault if the scrutinee *does* return.  A
    -- belt-and-braces approach would be to move this case into the
    -- code generator, and put a return point anyway that calls a
    -- runtime system error function.

coreToStgExpr e0@(Case scrut bndr _ [alt]) = do
  | isUnsafeEqualityProof scrut
  , isDeadBinder bndr -- We can only discard the case if the case-binder is dead
                      -- It usually is, but see #18227
  , (_,_,rhs) <- alt
  = coreToStgExpr rhs
    -- See (U2) in Note [Implementing unsafeCoerce] in base:Unsafe.Coerce
-}

-- The normal case for case-expressions
coreToStgExpr (Case Expr Var
scrut Var
bndr Type
_ [Alt Var]
alts)
  = do { StgExpr
scrut2 <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
scrut
       ; [(AltCon, [Var], StgExpr)]
alts2 <- forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [(Var
bndr, HowBound
LambdaBound)] (forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Alt Var -> CtsM (AltCon, [Var], StgExpr)
vars_alt [Alt Var]
alts)
       ; forall (m :: * -> *) a. Monad m => a -> m a
return (forall (pass :: StgPass).
GenStgExpr pass
-> BinderP pass -> AltType -> [GenStgAlt pass] -> GenStgExpr pass
StgCase StgExpr
scrut2 Var
bndr (Var -> [Alt Var] -> AltType
mkStgAltType Var
bndr [Alt Var]
alts) [(AltCon, [Var], StgExpr)]
alts2) }
  where
    vars_alt :: CoreAlt -> CtsM (AltCon, [Var], StgExpr)
    vars_alt :: Alt Var -> CtsM (AltCon, [Var], StgExpr)
vars_alt (Alt AltCon
con [Var]
binders Expr Var
rhs)
      | DataAlt DataCon
c <- AltCon
con, DataCon
c forall a. Eq a => a -> a -> Bool
== DataCon
unboxedUnitDataCon
      = -- This case is a bit smelly.
        -- See Note [Nullary unboxed tuple] in GHC.Core.Type
        -- where a nullary tuple is mapped to (State# World#)
        ASSERT( null binders )
        do { StgExpr
rhs2 <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
rhs
           ; forall (m :: * -> *) a. Monad m => a -> m a
return (AltCon
DEFAULT, [], StgExpr
rhs2)  }
      | Bool
otherwise
      = let     -- Remove type variables
            binders' :: [Var]
binders' = [Var] -> [Var]
filterStgBinders [Var]
binders
        in
        forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [(Var
b, HowBound
LambdaBound) | Var
b <- [Var]
binders'] forall a b. (a -> b) -> a -> b
$ do
        StgExpr
rhs2 <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
rhs
        forall (m :: * -> *) a. Monad m => a -> m a
return (AltCon
con, [Var]
binders', StgExpr
rhs2)

coreToStgExpr (Let CoreBind
bind Expr Var
body) = CoreBind -> Expr Var -> CtsM StgExpr
coreToStgLet CoreBind
bind Expr Var
body
coreToStgExpr Expr Var
e               = forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"coreToStgExpr" (forall a. Outputable a => a -> SDoc
ppr Expr Var
e)

mkStgAltType :: Id -> [CoreAlt] -> AltType
mkStgAltType :: Var -> [Alt Var] -> AltType
mkStgAltType Var
bndr [Alt Var]
alts
  | Type -> Bool
isUnboxedTupleType Type
bndr_ty Bool -> Bool -> Bool
|| Type -> Bool
isUnboxedSumType Type
bndr_ty
  = JoinArity -> AltType
MultiValAlt (forall (t :: * -> *) a. Foldable t => t a -> JoinArity
length [PrimRep]
prim_reps)  -- always use MultiValAlt for unboxed tuples

  | Bool
otherwise
  = case [PrimRep]
prim_reps of
      [PrimRep
rep] | PrimRep -> Bool
isGcPtrRep PrimRep
rep ->
        case Type -> Maybe TyCon
tyConAppTyCon_maybe (Type -> Type
unwrapType Type
bndr_ty) of
          Just TyCon
tc
            | TyCon -> Bool
isAbstractTyCon TyCon
tc -> AltType
look_for_better_tycon
            | TyCon -> Bool
isAlgTyCon TyCon
tc      -> TyCon -> AltType
AlgAlt TyCon
tc
            | Bool
otherwise          -> ASSERT2( _is_poly_alt_tycon tc, ppr tc )
                                    AltType
PolyAlt
          Maybe TyCon
Nothing                -> AltType
PolyAlt
      [PrimRep
non_gcd] -> PrimRep -> AltType
PrimAlt PrimRep
non_gcd
      [PrimRep]
not_unary -> JoinArity -> AltType
MultiValAlt (forall (t :: * -> *) a. Foldable t => t a -> JoinArity
length [PrimRep]
not_unary)
  where
   bndr_ty :: Type
bndr_ty   = Var -> Type
idType Var
bndr
   prim_reps :: [PrimRep]
prim_reps = HasDebugCallStack => Type -> [PrimRep]
typePrimRep Type
bndr_ty

   _is_poly_alt_tycon :: TyCon -> Bool
_is_poly_alt_tycon TyCon
tc
        =  TyCon -> Bool
isFunTyCon TyCon
tc
        Bool -> Bool -> Bool
|| TyCon -> Bool
isPrimTyCon TyCon
tc   -- "Any" is lifted but primitive
        Bool -> Bool -> Bool
|| TyCon -> Bool
isFamilyTyCon TyCon
tc -- Type family; e.g. Any, or arising from strict
                            -- function application where argument has a
                            -- type-family type

   -- Sometimes, the TyCon is a AbstractTyCon which may not have any
   -- constructors inside it.  Then we may get a better TyCon by
   -- grabbing the one from a constructor alternative
   -- if one exists.
   look_for_better_tycon :: AltType
look_for_better_tycon
        | ((Alt (DataAlt DataCon
con) [Var]
_ Expr Var
_) : [Alt Var]
_) <- [Alt Var]
data_alts =
                TyCon -> AltType
AlgAlt (DataCon -> TyCon
dataConTyCon DataCon
con)
        | Bool
otherwise =
                ASSERT(null data_alts)
                AltType
PolyAlt
        where
                ([Alt Var]
data_alts, Maybe (Expr Var)
_deflt) = forall b. [Alt b] -> ([Alt b], Maybe (Expr b))
findDefault [Alt Var]
alts

-- ---------------------------------------------------------------------------
-- Applications
-- ---------------------------------------------------------------------------

coreToStgApp :: Id            -- Function
             -> [CoreArg]     -- Arguments
             -> [CoreTickish] -- Debug ticks
             -> CtsM StgExpr
coreToStgApp :: Var -> [Expr Var] -> [CoreTickish] -> CtsM StgExpr
coreToStgApp Var
f [Expr Var]
args [CoreTickish]
ticks = do
    ([StgArg]
args', [StgTickish]
ticks') <- [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs [Expr Var]
args
    HowBound
how_bound <- Var -> CtsM HowBound
lookupVarCts Var
f

    let
        n_val_args :: JoinArity
n_val_args       = forall b. [Arg b] -> JoinArity
valArgCount [Expr Var]
args

        -- Mostly, the arity info of a function is in the fn's IdInfo
        -- But new bindings introduced by CoreSat may not have no
        -- arity info; it would do us no good anyway.  For example:
        --      let f = \ab -> e in f
        -- No point in having correct arity info for f!
        -- Hence the hasArity stuff below.
        -- NB: f_arity is only consulted for LetBound things
        f_arity :: JoinArity
f_arity   = Var -> HowBound -> JoinArity
stgArity Var
f HowBound
how_bound
        saturated :: Bool
saturated = JoinArity
f_arity forall a. Ord a => a -> a -> Bool
<= JoinArity
n_val_args

        res_ty :: Type
res_ty = Expr Var -> Type
exprType (forall b. Expr b -> [Expr b] -> Expr b
mkApps (forall b. Var -> Expr b
Var Var
f) [Expr Var]
args)
        app :: StgExpr
app = case Var -> IdDetails
idDetails Var
f of
                DataConWorkId DataCon
dc
                  | Bool
saturated    -> forall (pass :: StgPass).
DataCon -> XConApp pass -> [StgArg] -> [Type] -> GenStgExpr pass
StgConApp DataCon
dc ConstructorNumber
NoNumber [StgArg]
args'
                                      ([Type] -> [Type]
dropRuntimeRepArgs (forall a. a -> Maybe a -> a
fromMaybe [] (Type -> Maybe [Type]
tyConAppArgs_maybe Type
res_ty)))

                -- Some primitive operator that might be implemented as a library call.
                -- As noted by Note [Eta expanding primops] in GHC.Builtin.PrimOps
                -- we require that primop applications be saturated.
                PrimOpId PrimOp
op      -> ASSERT( saturated )
                                    forall (pass :: StgPass).
StgOp -> [StgArg] -> Type -> GenStgExpr pass
StgOpApp (PrimOp -> StgOp
StgPrimOp PrimOp
op) [StgArg]
args' Type
res_ty

                -- A call to some primitive Cmm function.
                FCallId (CCall (CCallSpec (StaticTarget SourceText
_ CLabelString
lbl (Just Unit
pkgId) Bool
True)
                                          CCallConv
PrimCallConv Safety
_))
                                 -> ASSERT( saturated )
                                    forall (pass :: StgPass).
StgOp -> [StgArg] -> Type -> GenStgExpr pass
StgOpApp (PrimCall -> StgOp
StgPrimCallOp (CLabelString -> Unit -> PrimCall
PrimCall CLabelString
lbl Unit
pkgId)) [StgArg]
args' Type
res_ty

                -- A regular foreign call.
                FCallId ForeignCall
call     -> ASSERT( saturated )
                                    forall (pass :: StgPass).
StgOp -> [StgArg] -> Type -> GenStgExpr pass
StgOpApp (ForeignCall -> Type -> StgOp
StgFCallOp ForeignCall
call (Var -> Type
idType Var
f)) [StgArg]
args' Type
res_ty

                TickBoxOpId {}   -> forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"coreToStg TickBox" forall a b. (a -> b) -> a -> b
$ forall a. Outputable a => a -> SDoc
ppr (Var
f,[StgArg]
args')
                IdDetails
_other           -> forall (pass :: StgPass). Var -> [StgArg] -> GenStgExpr pass
StgApp Var
f [StgArg]
args'

        add_tick :: StgTickish -> GenStgExpr pass -> GenStgExpr pass
add_tick !StgTickish
t !GenStgExpr pass
e = forall (pass :: StgPass).
StgTickish -> GenStgExpr pass -> GenStgExpr pass
StgTick StgTickish
t GenStgExpr pass
e
        tapp :: StgExpr
tapp = forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr forall (pass :: StgPass).
StgTickish -> GenStgExpr pass -> GenStgExpr pass
add_tick StgExpr
app (forall a b. (a -> b) -> [a] -> [b]
map (Type -> CoreTickish -> StgTickish
coreToStgTick Type
res_ty) [CoreTickish]
ticks forall a. [a] -> [a] -> [a]
++ [StgTickish]
ticks')

    -- Forcing these fixes a leak in the code generator, noticed while
    -- profiling for trac #4367
    StgExpr
app seq :: forall a b. a -> b -> b
`seq` forall (m :: * -> *) a. Monad m => a -> m a
return StgExpr
tapp

-- ---------------------------------------------------------------------------
-- Argument lists
-- This is the guy that turns applications into A-normal form
-- ---------------------------------------------------------------------------

coreToStgArgs :: [CoreArg] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs :: [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs []
  = forall (m :: * -> *) a. Monad m => a -> m a
return ([], [])

coreToStgArgs (Type Type
_ : [Expr Var]
args) = do     -- Type argument
    ([StgArg]
args', [StgTickish]
ts) <- [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs [Expr Var]
args
    forall (m :: * -> *) a. Monad m => a -> m a
return ([StgArg]
args', [StgTickish]
ts)

coreToStgArgs (Coercion Coercion
_ : [Expr Var]
args) -- Coercion argument; See Note [Coercion tokens]
  = do { ([StgArg]
args', [StgTickish]
ts) <- [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs [Expr Var]
args
       ; forall (m :: * -> *) a. Monad m => a -> m a
return (Var -> StgArg
StgVarArg Var
coercionTokenId forall a. a -> [a] -> [a]
: [StgArg]
args', [StgTickish]
ts) }

coreToStgArgs (Tick CoreTickish
t Expr Var
e : [Expr Var]
args)
  = ASSERT( not (tickishIsCode t) )
    do { ([StgArg]
args', [StgTickish]
ts) <- [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs (Expr Var
e forall a. a -> [a] -> [a]
: [Expr Var]
args)
       ; let !t' :: StgTickish
t' = Type -> CoreTickish -> StgTickish
coreToStgTick (Expr Var -> Type
exprType Expr Var
e) CoreTickish
t
       ; forall (m :: * -> *) a. Monad m => a -> m a
return ([StgArg]
args', StgTickish
t'forall a. a -> [a] -> [a]
:[StgTickish]
ts) }

coreToStgArgs (Expr Var
arg : [Expr Var]
args) = do         -- Non-type argument
    ([StgArg]
stg_args, [StgTickish]
ticks) <- [Expr Var] -> CtsM ([StgArg], [StgTickish])
coreToStgArgs [Expr Var]
args
    StgExpr
arg' <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
arg
    let
        ([StgTickish]
aticks, StgExpr
arg'') = forall (p :: StgPass).
(StgTickish -> Bool)
-> GenStgExpr p -> ([StgTickish], GenStgExpr p)
stripStgTicksTop forall (pass :: TickishPass). GenTickish pass -> Bool
tickishFloatable StgExpr
arg'
        stg_arg :: StgArg
stg_arg = case StgExpr
arg'' of
                       StgApp Var
v []        -> Var -> StgArg
StgVarArg Var
v
                       StgConApp DataCon
con XConApp 'Vanilla
_ [] [Type]
_ -> Var -> StgArg
StgVarArg (DataCon -> Var
dataConWorkId DataCon
con)
                       StgLit Literal
lit         -> Literal -> StgArg
StgLitArg Literal
lit
                       StgExpr
_                  -> forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"coreToStgArgs" (forall a. Outputable a => a -> SDoc
ppr Expr Var
arg)

        -- WARNING: what if we have an argument like (v `cast` co)
        --          where 'co' changes the representation type?
        --          (This really only happens if co is unsafe.)
        -- Then all the getArgAmode stuff in CgBindery will set the
        -- cg_rep of the CgIdInfo based on the type of v, rather
        -- than the type of 'co'.
        -- This matters particularly when the function is a primop
        -- or foreign call.
        -- Wanted: a better solution than this hacky warning

    Platform
platform <- DynFlags -> Platform
targetPlatform forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
    let
        arg_rep :: [PrimRep]
arg_rep = HasDebugCallStack => Type -> [PrimRep]
typePrimRep (Expr Var -> Type
exprType Expr Var
arg)
        stg_arg_rep :: [PrimRep]
stg_arg_rep = HasDebugCallStack => Type -> [PrimRep]
typePrimRep (StgArg -> Type
stgArgType StgArg
stg_arg)
        bad_args :: Bool
bad_args = Bool -> Bool
not (Platform -> [PrimRep] -> [PrimRep] -> Bool
primRepsCompatible Platform
platform [PrimRep]
arg_rep [PrimRep]
stg_arg_rep)

    WARN( bad_args, text "Dangerous-looking argument. Probable cause: bad unsafeCoerce#" $$ ppr arg )
     forall (m :: * -> *) a. Monad m => a -> m a
return (StgArg
stg_arg forall a. a -> [a] -> [a]
: [StgArg]
stg_args, [StgTickish]
ticks forall a. [a] -> [a] -> [a]
++ [StgTickish]
aticks)

coreToStgTick :: Type -- type of the ticked expression
              -> CoreTickish
              -> StgTickish
coreToStgTick :: Type -> CoreTickish -> StgTickish
coreToStgTick Type
_ty (HpcTick Module
m JoinArity
i)           = forall (pass :: TickishPass).
Module -> JoinArity -> GenTickish pass
HpcTick Module
m JoinArity
i
coreToStgTick Type
_ty (SourceNote RealSrcSpan
span String
nm)    = forall (pass :: TickishPass).
RealSrcSpan -> String -> GenTickish pass
SourceNote RealSrcSpan
span String
nm
coreToStgTick Type
_ty (ProfNote CostCentre
cc Bool
cnt Bool
scope) = forall (pass :: TickishPass).
CostCentre -> Bool -> Bool -> GenTickish pass
ProfNote CostCentre
cc Bool
cnt Bool
scope
coreToStgTick !Type
ty (Breakpoint XBreakpoint 'TickishPassCore
_ JoinArity
bid [XTickishId 'TickishPassCore]
fvs)  = forall (pass :: TickishPass).
XBreakpoint pass
-> JoinArity -> [XTickishId pass] -> GenTickish pass
Breakpoint Type
ty JoinArity
bid [XTickishId 'TickishPassCore]
fvs

-- ---------------------------------------------------------------------------
-- The magic for lets:
-- ---------------------------------------------------------------------------

coreToStgLet
         :: CoreBind     -- bindings
         -> CoreExpr     -- body
         -> CtsM StgExpr -- new let

coreToStgLet :: CoreBind -> Expr Var -> CtsM StgExpr
coreToStgLet CoreBind
bind Expr Var
body
  | NonRec Var
_ Expr Var
rhs <- CoreBind
bind, forall b. Expr b -> Bool
isTyCoArg Expr Var
rhs
  = Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
body

  | Bool
otherwise
  = do { (StgBinding
bind2, [(Var, HowBound)]
env_ext) <- CoreBind -> CtsM (StgBinding, [(Var, HowBound)])
vars_bind CoreBind
bind

          -- Do the body
         ; StgExpr
body2 <- forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [(Var, HowBound)]
env_ext forall a b. (a -> b) -> a -> b
$
                    Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
body

        -- Compute the new let-expression
        ; let new_let :: StgExpr
new_let | CoreBind -> Bool
isJoinBind CoreBind
bind
                      = forall (pass :: StgPass).
XLetNoEscape pass
-> GenStgBinding pass -> GenStgExpr pass -> GenStgExpr pass
StgLetNoEscape NoExtFieldSilent
noExtFieldSilent StgBinding
bind2 StgExpr
body2
                      | Bool
otherwise
                      = forall (pass :: StgPass).
XLet pass
-> GenStgBinding pass -> GenStgExpr pass -> GenStgExpr pass
StgLet NoExtFieldSilent
noExtFieldSilent StgBinding
bind2 StgExpr
body2

        ; forall (m :: * -> *) a. Monad m => a -> m a
return StgExpr
new_let }
  where
    mk_binding :: a -> Expr Var -> (a, HowBound)
mk_binding a
binder Expr Var
rhs
        = (a
binder, LetInfo -> JoinArity -> HowBound
LetBound LetInfo
NestedLet (Expr Var -> JoinArity
manifestArity Expr Var
rhs))

    vars_bind :: CoreBind
              -> CtsM (StgBinding,
                       [(Id, HowBound)])  -- extension to environment

    vars_bind :: CoreBind -> CtsM (StgBinding, [(Var, HowBound)])
vars_bind (NonRec Var
binder Expr Var
rhs) = do
        StgRhs
rhs2 <- (Var, Expr Var) -> CtsM StgRhs
coreToStgRhs (Var
binder,Expr Var
rhs)
        let
            env_ext_item :: (Var, HowBound)
env_ext_item = forall {a}. a -> Expr Var -> (a, HowBound)
mk_binding Var
binder Expr Var
rhs

        forall (m :: * -> *) a. Monad m => a -> m a
return (forall (pass :: StgPass).
BinderP pass -> GenStgRhs pass -> GenStgBinding pass
StgNonRec Var
binder StgRhs
rhs2, [(Var, HowBound)
env_ext_item])

    vars_bind (Rec [(Var, Expr Var)]
pairs)
      =    let
                binders :: [Var]
binders = forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> a
fst [(Var, Expr Var)]
pairs
                env_ext :: [(Var, HowBound)]
env_ext = [ forall {a}. a -> Expr Var -> (a, HowBound)
mk_binding Var
b Expr Var
rhs
                          | (Var
b,Expr Var
rhs) <- [(Var, Expr Var)]
pairs ]
           in
           forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [(Var, HowBound)]
env_ext forall a b. (a -> b) -> a -> b
$ do
              [StgRhs]
rhss2 <- forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Var, Expr Var) -> CtsM StgRhs
coreToStgRhs [(Var, Expr Var)]
pairs
              forall (m :: * -> *) a. Monad m => a -> m a
return (forall (pass :: StgPass).
[(BinderP pass, GenStgRhs pass)] -> GenStgBinding pass
StgRec ([Var]
binders forall a b. [a] -> [b] -> [(a, b)]
`zip` [StgRhs]
rhss2), [(Var, HowBound)]
env_ext)

coreToStgRhs :: (Id,CoreExpr)
             -> CtsM StgRhs

coreToStgRhs :: (Var, Expr Var) -> CtsM StgRhs
coreToStgRhs (Var
bndr, Expr Var
rhs) = do
    PreStgRhs
new_rhs <- Expr Var -> CtsM PreStgRhs
coreToPreStgRhs Expr Var
rhs
    forall (m :: * -> *) a. Monad m => a -> m a
return (Var -> PreStgRhs -> StgRhs
mkStgRhs Var
bndr PreStgRhs
new_rhs)

-- Represents the RHS of a binding for use with mk(Top)StgRhs.
data PreStgRhs = PreStgRhs [Id] StgExpr -- The [Id] is empty for thunks

-- Convert the RHS of a binding from Core to STG. This is a wrapper around
-- coreToStgExpr that can handle value lambdas.
coreToPreStgRhs :: CoreExpr -> CtsM PreStgRhs
coreToPreStgRhs :: Expr Var -> CtsM PreStgRhs
coreToPreStgRhs (Cast Expr Var
expr Coercion
_) = Expr Var -> CtsM PreStgRhs
coreToPreStgRhs Expr Var
expr
coreToPreStgRhs expr :: Expr Var
expr@(Lam Var
_ Expr Var
_) =
    let
        ([Var]
args, Expr Var
body) = Expr Var -> ([Var], Expr Var)
myCollectBinders Expr Var
expr
        args' :: [Var]
args'        = [Var] -> [Var]
filterStgBinders [Var]
args
    in
        forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [ (Var
a, HowBound
LambdaBound) | Var
a <- [Var]
args' ] forall a b. (a -> b) -> a -> b
$ do
          StgExpr
body' <- Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
body
          forall (m :: * -> *) a. Monad m => a -> m a
return ([Var] -> StgExpr -> PreStgRhs
PreStgRhs [Var]
args' StgExpr
body')
coreToPreStgRhs Expr Var
expr = [Var] -> StgExpr -> PreStgRhs
PreStgRhs [] forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Expr Var -> CtsM StgExpr
coreToStgExpr Expr Var
expr

-- Generate a top-level RHS. Any new cost centres generated for CAFs will be
-- appended to `CollectedCCs` argument.
mkTopStgRhs :: DynFlags -> Module -> CollectedCCs
            -> Id -> PreStgRhs -> (StgRhs, CollectedCCs)

mkTopStgRhs :: DynFlags
-> Module
-> CollectedCCs
-> Var
-> PreStgRhs
-> (StgRhs, CollectedCCs)
mkTopStgRhs DynFlags
dflags Module
this_mod CollectedCCs
ccs Var
bndr (PreStgRhs [Var]
bndrs StgExpr
rhs)
  | Bool -> Bool
not (forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Var]
bndrs)
  = -- The list of arguments is non-empty, so not CAF
    ( forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                    CostCentreStack
dontCareCCS
                    UpdateFlag
ReEntrant
                    [Var]
bndrs StgExpr
rhs
    , CollectedCCs
ccs )

  -- After this point we know that `bndrs` is empty,
  -- so this is not a function binding
  | StgConApp DataCon
con XConApp 'Vanilla
mn [StgArg]
args [Type]
_ <- StgExpr
unticked_rhs
  , -- Dynamic StgConApps are updatable
    Bool -> Bool
not (DynFlags -> Module -> DataCon -> [StgArg] -> Bool
isDllConApp DynFlags
dflags Module
this_mod DataCon
con [StgArg]
args)
  = -- CorePrep does this right, but just to make sure
    ASSERT2( not (isUnboxedTupleDataCon con || isUnboxedSumDataCon con)
           , ppr bndr $$ ppr con $$ ppr args)
    ( forall (pass :: StgPass).
CostCentreStack
-> DataCon
-> ConstructorNumber
-> [StgTickish]
-> [StgArg]
-> GenStgRhs pass
StgRhsCon CostCentreStack
dontCareCCS DataCon
con XConApp 'Vanilla
mn [StgTickish]
ticks [StgArg]
args, CollectedCCs
ccs )

  -- Otherwise it's a CAF, see Note [Cost-centre initialization plan].
  | GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_AutoSccsOnIndividualCafs DynFlags
dflags
  = ( forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                    CostCentreStack
caf_ccs
                    UpdateFlag
upd_flag [] StgExpr
rhs
    , CostCentre -> CostCentreStack -> CollectedCCs -> CollectedCCs
collectCC CostCentre
caf_cc CostCentreStack
caf_ccs CollectedCCs
ccs )

  | Bool
otherwise
  = ( forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                    CostCentreStack
all_cafs_ccs
                    UpdateFlag
upd_flag [] StgExpr
rhs
    , CollectedCCs
ccs )

  where
    ([StgTickish]
ticks, StgExpr
unticked_rhs) = forall (p :: StgPass).
(StgTickish -> Bool)
-> GenStgExpr p -> ([StgTickish], GenStgExpr p)
stripStgTicksTop (Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (pass :: TickishPass). GenTickish pass -> Bool
tickishIsCode) StgExpr
rhs

    upd_flag :: UpdateFlag
upd_flag | Demand -> Bool
isUsedOnceDmd (Var -> Demand
idDemandInfo Var
bndr) = UpdateFlag
SingleEntry
             | Bool
otherwise                         = UpdateFlag
Updatable

    -- CAF cost centres generated for -fcaf-all
    caf_cc :: CostCentre
caf_cc = Var -> Module -> CostCentre
mkAutoCC Var
bndr Module
modl
    caf_ccs :: CostCentreStack
caf_ccs = CostCentre -> CostCentreStack
mkSingletonCCS CostCentre
caf_cc
           -- careful: the binder might be :Main.main,
           -- which doesn't belong to module mod_name.
           -- bug #249, tests prof001, prof002
    modl :: Module
modl | Just Module
m <- Name -> Maybe Module
nameModule_maybe (Var -> Name
idName Var
bndr) = Module
m
         | Bool
otherwise = Module
this_mod

    -- default CAF cost centre
    (CostCentre
_, CostCentreStack
all_cafs_ccs) = Module -> (CostCentre, CostCentreStack)
getAllCAFsCC Module
this_mod

-- Generate a non-top-level RHS. Cost-centre is always currentCCS,
-- see Note [Cost-centre initialization plan].
mkStgRhs :: Id -> PreStgRhs -> StgRhs
mkStgRhs :: Var -> PreStgRhs -> StgRhs
mkStgRhs Var
bndr (PreStgRhs [Var]
bndrs StgExpr
rhs)
  | Bool -> Bool
not (forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Var]
bndrs)
  = forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                  CostCentreStack
currentCCS
                  UpdateFlag
ReEntrant
                  [Var]
bndrs StgExpr
rhs

  -- After this point we know that `bndrs` is empty,
  -- so this is not a function binding
  | Var -> Bool
isJoinId Var
bndr -- must be a nullary join point
  = ASSERT(idJoinArity bndr == 0)
    forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                  CostCentreStack
currentCCS
                  UpdateFlag
ReEntrant -- ignored for LNE
                  [] StgExpr
rhs

  | StgConApp DataCon
con XConApp 'Vanilla
mn [StgArg]
args [Type]
_ <- StgExpr
unticked_rhs
  = forall (pass :: StgPass).
CostCentreStack
-> DataCon
-> ConstructorNumber
-> [StgTickish]
-> [StgArg]
-> GenStgRhs pass
StgRhsCon CostCentreStack
currentCCS DataCon
con XConApp 'Vanilla
mn [StgTickish]
ticks [StgArg]
args

  | Bool
otherwise
  = forall (pass :: StgPass).
XRhsClosure pass
-> CostCentreStack
-> UpdateFlag
-> [BinderP pass]
-> GenStgExpr pass
-> GenStgRhs pass
StgRhsClosure NoExtFieldSilent
noExtFieldSilent
                  CostCentreStack
currentCCS
                  UpdateFlag
upd_flag [] StgExpr
rhs
  where
    ([StgTickish]
ticks, StgExpr
unticked_rhs) = forall (p :: StgPass).
(StgTickish -> Bool)
-> GenStgExpr p -> ([StgTickish], GenStgExpr p)
stripStgTicksTop (Bool -> Bool
not forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (pass :: TickishPass). GenTickish pass -> Bool
tickishIsCode) StgExpr
rhs

    upd_flag :: UpdateFlag
upd_flag | Demand -> Bool
isUsedOnceDmd (Var -> Demand
idDemandInfo Var
bndr) = UpdateFlag
SingleEntry
             | Bool
otherwise                         = UpdateFlag
Updatable

  {-
    SDM: disabled.  Eval/Apply can't handle functions with arity zero very
    well; and making these into simple non-updatable thunks breaks other
    assumptions (namely that they will be entered only once).

    upd_flag | isPAP env rhs  = ReEntrant
             | otherwise      = Updatable

-- Detect thunks which will reduce immediately to PAPs, and make them
-- non-updatable.  This has several advantages:
--
--         - the non-updatable thunk behaves exactly like the PAP,
--
--         - the thunk is more efficient to enter, because it is
--           specialised to the task.
--
--         - we save one update frame, one stg_update_PAP, one update
--           and lots of PAP_enters.
--
--         - in the case where the thunk is top-level, we save building
--           a black hole and furthermore the thunk isn't considered to
--           be a CAF any more, so it doesn't appear in any SRTs.
--
-- We do it here, because the arity information is accurate, and we need
-- to do it before the SRT pass to save the SRT entries associated with
-- any top-level PAPs.

isPAP env (StgApp f args) = listLengthCmp args arity == LT -- idArity f > length args
                              where
                                 arity = stgArity f (lookupBinding env f)
isPAP env _               = False

-}

{- ToDo:
          upd = if isOnceDem dem
                    then (if isNotTop toplev
                            then SingleEntry    -- HA!  Paydirt for "dem"
                            else
                     (if debugIsOn then trace "WARNING: SE CAFs unsupported, forcing UPD instead" else id) $
                     Updatable)
                else Updatable
        -- For now we forbid SingleEntry CAFs; they tickle the
        -- ASSERT in rts/Storage.c line 215 at newCAF() re mut_link,
        -- and I don't understand why.  There's only one SE_CAF (well,
        -- only one that tickled a great gaping bug in an earlier attempt
        -- at ClosureInfo.getEntryConvention) in the whole of nofib,
        -- specifically Main.lvl6 in spectral/cryptarithm2.
        -- So no great loss.  KSW 2000-07.
-}

-- ---------------------------------------------------------------------------
-- A monad for the core-to-STG pass
-- ---------------------------------------------------------------------------

-- There's a lot of stuff to pass around, so we use this CtsM
-- ("core-to-STG monad") monad to help.  All the stuff here is only passed
-- *down*.

newtype CtsM a = CtsM
    { forall a. CtsM a -> DynFlags -> IdEnv HowBound -> a
unCtsM :: DynFlags -- Needed for checking for bad coercions in coreToStgArgs
             -> IdEnv HowBound
             -> a
    }
    deriving (forall a b. a -> CtsM b -> CtsM a
forall a b. (a -> b) -> CtsM a -> CtsM b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
<$ :: forall a b. a -> CtsM b -> CtsM a
$c<$ :: forall a b. a -> CtsM b -> CtsM a
fmap :: forall a b. (a -> b) -> CtsM a -> CtsM b
$cfmap :: forall a b. (a -> b) -> CtsM a -> CtsM b
Functor)

data HowBound
  = ImportBound         -- Used only as a response to lookupBinding; never
                        -- exists in the range of the (IdEnv HowBound)

  | LetBound            -- A let(rec) in this module
        LetInfo         -- Whether top level or nested
        Arity           -- Its arity (local Ids don't have arity info at this point)

  | LambdaBound         -- Used for both lambda and case
  deriving (HowBound -> HowBound -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: HowBound -> HowBound -> Bool
$c/= :: HowBound -> HowBound -> Bool
== :: HowBound -> HowBound -> Bool
$c== :: HowBound -> HowBound -> Bool
Eq)

data LetInfo
  = TopLet              -- top level things
  | NestedLet
  deriving (LetInfo -> LetInfo -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: LetInfo -> LetInfo -> Bool
$c/= :: LetInfo -> LetInfo -> Bool
== :: LetInfo -> LetInfo -> Bool
$c== :: LetInfo -> LetInfo -> Bool
Eq)

-- For a let(rec)-bound variable, x, we record LiveInfo, the set of
-- variables that are live if x is live.  This LiveInfo comprises
--         (a) dynamic live variables (ones with a non-top-level binding)
--         (b) static live variables (CAFs or things that refer to CAFs)
--
-- For "normal" variables (a) is just x alone.  If x is a let-no-escaped
-- variable then x is represented by a code pointer and a stack pointer
-- (well, one for each stack).  So all of the variables needed in the
-- execution of x are live if x is, and are therefore recorded in the
-- LetBound constructor; x itself *is* included.
--
-- The set of dynamic live variables is guaranteed ot have no further
-- let-no-escaped variables in it.

-- The std monad functions:

initCts :: DynFlags -> IdEnv HowBound -> CtsM a -> a
initCts :: forall a. DynFlags -> IdEnv HowBound -> CtsM a -> a
initCts DynFlags
dflags IdEnv HowBound
env CtsM a
m = forall a. CtsM a -> DynFlags -> IdEnv HowBound -> a
unCtsM CtsM a
m DynFlags
dflags IdEnv HowBound
env



{-# INLINE thenCts #-}
{-# INLINE returnCts #-}

returnCts :: a -> CtsM a
returnCts :: forall a. a -> CtsM a
returnCts a
e = forall a. (DynFlags -> IdEnv HowBound -> a) -> CtsM a
CtsM forall a b. (a -> b) -> a -> b
$ \DynFlags
_ IdEnv HowBound
_ -> a
e

thenCts :: CtsM a -> (a -> CtsM b) -> CtsM b
thenCts :: forall a b. CtsM a -> (a -> CtsM b) -> CtsM b
thenCts CtsM a
m a -> CtsM b
k = forall a. (DynFlags -> IdEnv HowBound -> a) -> CtsM a
CtsM forall a b. (a -> b) -> a -> b
$ \DynFlags
dflags IdEnv HowBound
env
  -> forall a. CtsM a -> DynFlags -> IdEnv HowBound -> a
unCtsM (a -> CtsM b
k (forall a. CtsM a -> DynFlags -> IdEnv HowBound -> a
unCtsM CtsM a
m DynFlags
dflags IdEnv HowBound
env)) DynFlags
dflags IdEnv HowBound
env

instance Applicative CtsM where
    pure :: forall a. a -> CtsM a
pure = forall a. a -> CtsM a
returnCts
    <*> :: forall a b. CtsM (a -> b) -> CtsM a -> CtsM b
(<*>) = forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap

instance Monad CtsM where
    >>= :: forall a b. CtsM a -> (a -> CtsM b) -> CtsM b
(>>=)  = forall a b. CtsM a -> (a -> CtsM b) -> CtsM b
thenCts

instance HasDynFlags CtsM where
    getDynFlags :: CtsM DynFlags
getDynFlags = forall a. (DynFlags -> IdEnv HowBound -> a) -> CtsM a
CtsM forall a b. (a -> b) -> a -> b
$ \DynFlags
dflags IdEnv HowBound
_ -> DynFlags
dflags

-- Functions specific to this monad:

extendVarEnvCts :: [(Id, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts :: forall a. [(Var, HowBound)] -> CtsM a -> CtsM a
extendVarEnvCts [(Var, HowBound)]
ids_w_howbound CtsM a
expr
   =    forall a. (DynFlags -> IdEnv HowBound -> a) -> CtsM a
CtsM forall a b. (a -> b) -> a -> b
$   \DynFlags
dflags IdEnv HowBound
env
   -> forall a. CtsM a -> DynFlags -> IdEnv HowBound -> a
unCtsM CtsM a
expr DynFlags
dflags (forall a. VarEnv a -> [(Var, a)] -> VarEnv a
extendVarEnvList IdEnv HowBound
env [(Var, HowBound)]
ids_w_howbound)

lookupVarCts :: Id -> CtsM HowBound
lookupVarCts :: Var -> CtsM HowBound
lookupVarCts Var
v = forall a. (DynFlags -> IdEnv HowBound -> a) -> CtsM a
CtsM forall a b. (a -> b) -> a -> b
$ \DynFlags
_ IdEnv HowBound
env -> IdEnv HowBound -> Var -> HowBound
lookupBinding IdEnv HowBound
env Var
v

lookupBinding :: IdEnv HowBound -> Id -> HowBound
lookupBinding :: IdEnv HowBound -> Var -> HowBound
lookupBinding IdEnv HowBound
env Var
v = case forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv IdEnv HowBound
env Var
v of
                        Just HowBound
xx -> HowBound
xx
                        Maybe HowBound
Nothing -> ASSERT2( isGlobalId v, ppr v ) ImportBound

getAllCAFsCC :: Module -> (CostCentre, CostCentreStack)
getAllCAFsCC :: Module -> (CostCentre, CostCentreStack)
getAllCAFsCC Module
this_mod =
    let
      span :: SrcSpan
span = CLabelString -> SrcSpan
mkGeneralSrcSpan (String -> CLabelString
mkFastString String
"<entire-module>") -- XXX do better
      all_cafs_cc :: CostCentre
all_cafs_cc  = Module -> SrcSpan -> CostCentre
mkAllCafsCC Module
this_mod SrcSpan
span
      all_cafs_ccs :: CostCentreStack
all_cafs_ccs = CostCentre -> CostCentreStack
mkSingletonCCS CostCentre
all_cafs_cc
    in
      (CostCentre
all_cafs_cc, CostCentreStack
all_cafs_ccs)

-- Misc.

filterStgBinders :: [Var] -> [Var]
filterStgBinders :: [Var] -> [Var]
filterStgBinders [Var]
bndrs = forall a. (a -> Bool) -> [a] -> [a]
filter Var -> Bool
isId [Var]
bndrs

myCollectBinders :: Expr Var -> ([Var], Expr Var)
myCollectBinders :: Expr Var -> ([Var], Expr Var)
myCollectBinders Expr Var
expr
  = forall {a}. [a] -> Expr a -> ([a], Expr a)
go [] Expr Var
expr
  where
    go :: [a] -> Expr a -> ([a], Expr a)
go [a]
bs (Lam a
b Expr a
e)          = [a] -> Expr a -> ([a], Expr a)
go (a
bforall a. a -> [a] -> [a]
:[a]
bs) Expr a
e
    go [a]
bs (Cast Expr a
e Coercion
_)         = [a] -> Expr a -> ([a], Expr a)
go [a]
bs Expr a
e
    go [a]
bs Expr a
e                  = (forall a. [a] -> [a]
reverse [a]
bs, Expr a
e)

-- | Precondition: argument expression is an 'App', and there is a 'Var' at the
-- head of the 'App' chain.
myCollectArgs :: CoreExpr -> (Id, [CoreArg], [CoreTickish])
myCollectArgs :: Expr Var -> (Var, [Expr Var], [CoreTickish])
myCollectArgs Expr Var
expr
  = Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go Expr Var
expr [] []
  where
    go :: Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go (Var Var
v)          [Expr Var]
as [CoreTickish]
ts = (Var
v, [Expr Var]
as, [CoreTickish]
ts)
    go (App Expr Var
f Expr Var
a)        [Expr Var]
as [CoreTickish]
ts = Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go Expr Var
f (Expr Var
aforall a. a -> [a] -> [a]
:[Expr Var]
as) [CoreTickish]
ts
    go (Tick CoreTickish
t Expr Var
e)       [Expr Var]
as [CoreTickish]
ts = ASSERT2( not (tickishIsCode t) || all isTypeArg as
                                       , ppr e $$ ppr as $$ ppr ts )
                                -- See Note [Ticks in applications]
                                Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go Expr Var
e [Expr Var]
as (CoreTickish
tforall a. a -> [a] -> [a]
:[CoreTickish]
ts) -- ticks can appear in type apps
    go (Cast Expr Var
e Coercion
_)       [Expr Var]
as [CoreTickish]
ts = Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go Expr Var
e [Expr Var]
as [CoreTickish]
ts
    go (Lam Var
b Expr Var
e)        [Expr Var]
as [CoreTickish]
ts
       | Var -> Bool
isTyVar Var
b            = Expr Var
-> [Expr Var] -> [CoreTickish] -> (Var, [Expr Var], [CoreTickish])
go Expr Var
e [Expr Var]
as [CoreTickish]
ts -- Note [Collect args]
    go Expr Var
_                [Expr Var]
_  [CoreTickish]
_  = forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"CoreToStg.myCollectArgs" (forall a. Outputable a => a -> SDoc
ppr Expr Var
expr)

{- Note [Collect args]
~~~~~~~~~~~~~~~~~~~~~~
This big-lambda case occurred following a rather obscure eta expansion.
It all seems a bit yukky to me.

Note [Ticks in applications]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We can get an application like
   (tick t f) True False
via inlining in the CorePrep pass; see Note [Inlining in CorePrep]
in GHC.CoreToStg.Prep.  The tick does not satisfy tickishIsCode;
the inlining-in-CorePrep happens for cpExprIsTrivial which tests
tickishIsCode.

So we test the same thing here, pushing any non-code ticks to
the top (they don't generate any code, after all).  This showed
up in the fallout from fixing #19360.
-}

stgArity :: Id -> HowBound -> Arity
stgArity :: Var -> HowBound -> JoinArity
stgArity Var
_ (LetBound LetInfo
_ JoinArity
arity) = JoinArity
arity
stgArity Var
f HowBound
ImportBound        = Var -> JoinArity
idArity Var
f
stgArity Var
_ HowBound
LambdaBound        = JoinArity
0