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

\section[CoreMonad]{The core pipeline monad}
-}

{-# LANGUAGE CPP, UndecidableInstances #-}

module CoreMonad (
    -- * Configuration of the core-to-core passes
    CoreToDo(..), runWhen, runMaybe,
    SimplifierMode(..),
    FloatOutSwitches(..),
    pprPassDetails,

    -- * Plugins
    PluginPass, bindsOnlyPass,

    -- * Counting
    SimplCount, doSimplTick, doFreeSimplTick, simplCountN,
    pprSimplCount, plusSimplCount, zeroSimplCount,
    isZeroSimplCount, hasDetailedCounts, Tick(..),

    -- * The monad
    CoreM, runCoreM,

    -- ** Reading from the monad
    getHscEnv, getRuleBase, getModule,
    getDynFlags, getOrigNameCache, getPackageFamInstEnv,
    getPrintUnqualified,

    -- ** Writing to the monad
    addSimplCount,

    -- ** Lifting into the monad
    liftIO, liftIOWithCount,
    liftIO1, liftIO2, liftIO3, liftIO4,

    -- ** Global initialization
    reinitializeGlobals,

    -- ** Dealing with annotations
    getAnnotations, getFirstAnnotations,

    -- ** Screen output
    putMsg, putMsgS, errorMsg, errorMsgS,
    fatalErrorMsg, fatalErrorMsgS,
    debugTraceMsg, debugTraceMsgS,
    dumpIfSet_dyn,

#ifdef GHCI
    -- * Getting 'Name's
    thNameToGhcName
#endif
  ) where

#ifdef GHCI
import Name( Name )
#endif
import CoreSyn
import HscTypes
import Module
import DynFlags
import StaticFlags
import Rules            ( RuleBase )
import BasicTypes       ( CompilerPhase(..) )
import Annotations

import IOEnv hiding     ( liftIO, failM, failWithM )
import qualified IOEnv  ( liftIO )
import TcEnv            ( tcLookupGlobal )
import TcRnMonad        ( initTcForLookup )
import Var
import Outputable
import FastString
import qualified ErrUtils as Err
import Maybes
import UniqSupply
import UniqFM       ( UniqFM, mapUFM, filterUFM )
import MonadUtils

import ListSetOps       ( runs )
import Data.List
import Data.Ord
import Data.Dynamic
import Data.IORef
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Word
import qualified Control.Applicative as A
import Control.Monad

import Prelude hiding   ( read )

#ifdef GHCI
import Control.Concurrent.MVar (MVar)
import Linker ( PersistentLinkerState, saveLinkerGlobals, restoreLinkerGlobals )
import {-# SOURCE #-} TcSplice ( lookupThName_maybe )
import qualified Language.Haskell.TH as TH
#else
saveLinkerGlobals :: IO ()
saveLinkerGlobals = return ()

restoreLinkerGlobals :: () -> IO ()
restoreLinkerGlobals () = return ()
#endif


{-
************************************************************************
*                                                                      *
              The CoreToDo type and related types
          Abstraction of core-to-core passes to run.
*                                                                      *
************************************************************************
-}

data CoreToDo           -- These are diff core-to-core passes,
                        -- which may be invoked in any order,
                        -- as many times as you like.

  = CoreDoSimplify      -- The core-to-core simplifier.
        Int                    -- Max iterations
        SimplifierMode
  | CoreDoPluginPass String PluginPass
  | CoreDoFloatInwards
  | CoreDoFloatOutwards FloatOutSwitches
  | CoreLiberateCase
  | CoreDoPrintCore
  | CoreDoStaticArgs
  | CoreDoCallArity
  | CoreDoStrictness
  | CoreDoWorkerWrapper
  | CoreDoSpecialising
  | CoreDoSpecConstr
  | CoreCSE
  | CoreDoRuleCheck CompilerPhase String   -- Check for non-application of rules
                                           -- matching this string
  | CoreDoVectorisation
  | CoreDoNothing                -- Useful when building up
  | CoreDoPasses [CoreToDo]      -- lists of these things

  | CoreDesugar    -- Right after desugaring, no simple optimisation yet!
  | CoreDesugarOpt -- CoreDesugarXXX: Not strictly a core-to-core pass, but produces
                       --                 Core output, and hence useful to pass to endPass

  | CoreTidy
  | CorePrep

instance Outputable CoreToDo where
  ppr (CoreDoSimplify _ _)     = ptext (sLit "Simplifier")
  ppr (CoreDoPluginPass s _)   = ptext (sLit "Core plugin: ") <+> text s
  ppr CoreDoFloatInwards       = ptext (sLit "Float inwards")
  ppr (CoreDoFloatOutwards f)  = ptext (sLit "Float out") <> parens (ppr f)
  ppr CoreLiberateCase         = ptext (sLit "Liberate case")
  ppr CoreDoStaticArgs         = ptext (sLit "Static argument")
  ppr CoreDoCallArity          = ptext (sLit "Called arity analysis")
  ppr CoreDoStrictness         = ptext (sLit "Demand analysis")
  ppr CoreDoWorkerWrapper      = ptext (sLit "Worker Wrapper binds")
  ppr CoreDoSpecialising       = ptext (sLit "Specialise")
  ppr CoreDoSpecConstr         = ptext (sLit "SpecConstr")
  ppr CoreCSE                  = ptext (sLit "Common sub-expression")
  ppr CoreDoVectorisation      = ptext (sLit "Vectorisation")
  ppr CoreDesugar              = ptext (sLit "Desugar (before optimization)")
  ppr CoreDesugarOpt           = ptext (sLit "Desugar (after optimization)")
  ppr CoreTidy                 = ptext (sLit "Tidy Core")
  ppr CorePrep                 = ptext (sLit "CorePrep")
  ppr CoreDoPrintCore          = ptext (sLit "Print core")
  ppr (CoreDoRuleCheck {})     = ptext (sLit "Rule check")
  ppr CoreDoNothing            = ptext (sLit "CoreDoNothing")
  ppr (CoreDoPasses {})        = ptext (sLit "CoreDoPasses")

pprPassDetails :: CoreToDo -> SDoc
pprPassDetails (CoreDoSimplify n md) = vcat [ ptext (sLit "Max iterations =") <+> int n
                                            , ppr md ]
pprPassDetails _ = Outputable.empty

data SimplifierMode             -- See comments in SimplMonad
  = SimplMode
        { sm_names      :: [String] -- Name(s) of the phase
        , sm_phase      :: CompilerPhase
        , sm_rules      :: Bool     -- Whether RULES are enabled
        , sm_inline     :: Bool     -- Whether inlining is enabled
        , sm_case_case  :: Bool     -- Whether case-of-case is enabled
        , sm_eta_expand :: Bool     -- Whether eta-expansion is enabled
        }

instance Outputable SimplifierMode where
    ppr (SimplMode { sm_phase = p, sm_names = ss
                   , sm_rules = r, sm_inline = i
                   , sm_eta_expand = eta, sm_case_case = cc })
       = ptext (sLit "SimplMode") <+> braces (
         sep [ ptext (sLit "Phase =") <+> ppr p <+>
               brackets (text (concat $ intersperse "," ss)) <> comma
             , pp_flag i   (sLit "inline") <> comma
             , pp_flag r   (sLit "rules") <> comma
             , pp_flag eta (sLit "eta-expand") <> comma
             , pp_flag cc  (sLit "case-of-case") ])
         where
           pp_flag f s = ppUnless f (ptext (sLit "no")) <+> ptext s

data FloatOutSwitches = FloatOutSwitches {
  floatOutLambdas   :: Maybe Int,  -- ^ Just n <=> float lambdas to top level, if
                                   -- doing so will abstract over n or fewer
                                   -- value variables
                                   -- Nothing <=> float all lambdas to top level,
                                   --             regardless of how many free variables
                                   -- Just 0 is the vanilla case: float a lambda
                                   --    iff it has no free vars

  floatOutConstants :: Bool,       -- ^ True <=> float constants to top level,
                                   --            even if they do not escape a lambda
  floatOutOverSatApps :: Bool      -- ^ True <=> float out over-saturated applications
                                   --            based on arity information.
                                   -- See Note [Floating over-saturated applications]
                                   -- in SetLevels
  }
instance Outputable FloatOutSwitches where
    ppr = pprFloatOutSwitches

pprFloatOutSwitches :: FloatOutSwitches -> SDoc
pprFloatOutSwitches sw
  = ptext (sLit "FOS") <+> (braces $
     sep $ punctuate comma $
     [ ptext (sLit "Lam =")    <+> ppr (floatOutLambdas sw)
     , ptext (sLit "Consts =") <+> ppr (floatOutConstants sw)
     , ptext (sLit "OverSatApps =")   <+> ppr (floatOutOverSatApps sw) ])

-- The core-to-core pass ordering is derived from the DynFlags:
runWhen :: Bool -> CoreToDo -> CoreToDo
runWhen True  do_this = do_this
runWhen False _       = CoreDoNothing

runMaybe :: Maybe a -> (a -> CoreToDo) -> CoreToDo
runMaybe (Just x) f = f x
runMaybe Nothing  _ = CoreDoNothing

{-
Note [RULEs enabled in SimplGently]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RULES are enabled when doing "gentle" simplification.  Two reasons:

  * We really want the class-op cancellation to happen:
        op (df d1 d2) --> $cop3 d1 d2
    because this breaks the mutual recursion between 'op' and 'df'

  * I wanted the RULE
        lift String ===> ...
    to work in Template Haskell when simplifying
    splices, so we get simpler code for literal strings

But watch out: list fusion can prevent floating.  So use phase control
to switch off those rules until after floating.


************************************************************************
*                                                                      *
             Types for Plugins
*                                                                      *
************************************************************************
-}

-- | A description of the plugin pass itself
type PluginPass = ModGuts -> CoreM ModGuts

bindsOnlyPass :: (CoreProgram -> CoreM CoreProgram) -> ModGuts -> CoreM ModGuts
bindsOnlyPass pass guts
  = do { binds' <- pass (mg_binds guts)
       ; return (guts { mg_binds = binds' }) }

{-
************************************************************************
*                                                                      *
             Counting and logging
*                                                                      *
************************************************************************
-}

verboseSimplStats :: Bool
verboseSimplStats = opt_PprStyle_Debug          -- For now, anyway

zeroSimplCount     :: DynFlags -> SimplCount
isZeroSimplCount   :: SimplCount -> Bool
hasDetailedCounts  :: SimplCount -> Bool
pprSimplCount      :: SimplCount -> SDoc
doSimplTick        :: DynFlags -> Tick -> SimplCount -> SimplCount
doFreeSimplTick    ::             Tick -> SimplCount -> SimplCount
plusSimplCount     :: SimplCount -> SimplCount -> SimplCount

data SimplCount
   = VerySimplCount !Int        -- Used when don't want detailed stats

   | SimplCount {
        ticks   :: !Int,        -- Total ticks
        details :: !TickCounts, -- How many of each type

        n_log   :: !Int,        -- N
        log1    :: [Tick],      -- Last N events; <= opt_HistorySize,
                                --   most recent first
        log2    :: [Tick]       -- Last opt_HistorySize events before that
                                -- Having log1, log2 lets us accumulate the
                                -- recent history reasonably efficiently
     }

type TickCounts = Map Tick Int

simplCountN :: SimplCount -> Int
simplCountN (VerySimplCount n)         = n
simplCountN (SimplCount { ticks = n }) = n

zeroSimplCount dflags
                -- This is where we decide whether to do
                -- the VerySimpl version or the full-stats version
  | dopt Opt_D_dump_simpl_stats dflags
  = SimplCount {ticks = 0, details = Map.empty,
                n_log = 0, log1 = [], log2 = []}
  | otherwise
  = VerySimplCount 0

isZeroSimplCount (VerySimplCount n)         = n==0
isZeroSimplCount (SimplCount { ticks = n }) = n==0

hasDetailedCounts (VerySimplCount {}) = False
hasDetailedCounts (SimplCount {})     = True

doFreeSimplTick tick sc@SimplCount { details = dts }
  = sc { details = dts `addTick` tick }
doFreeSimplTick _ sc = sc

doSimplTick dflags tick
    sc@(SimplCount { ticks = tks, details = dts, n_log = nl, log1 = l1 })
  | nl >= historySize dflags = sc1 { n_log = 1, log1 = [tick], log2 = l1 }
  | otherwise                = sc1 { n_log = nl+1, log1 = tick : l1 }
  where
    sc1 = sc { ticks = tks+1, details = dts `addTick` tick }

doSimplTick _ _ (VerySimplCount n) = VerySimplCount (n+1)


-- Don't use Map.unionWith because that's lazy, and we want to
-- be pretty strict here!
addTick :: TickCounts -> Tick -> TickCounts
addTick fm tick = case Map.lookup tick fm of
                        Nothing -> Map.insert tick 1 fm
                        Just n  -> n1 `seq` Map.insert tick n1 fm
                                where
                                   n1 = n+1


plusSimplCount sc1@(SimplCount { ticks = tks1, details = dts1 })
               sc2@(SimplCount { ticks = tks2, details = dts2 })
  = log_base { ticks = tks1 + tks2, details = Map.unionWith (+) dts1 dts2 }
  where
        -- A hackish way of getting recent log info
    log_base | null (log1 sc2) = sc1    -- Nothing at all in sc2
             | null (log2 sc2) = sc2 { log2 = log1 sc1 }
             | otherwise       = sc2

plusSimplCount (VerySimplCount n) (VerySimplCount m) = VerySimplCount (n+m)
plusSimplCount _                  _                  = panic "plusSimplCount"
       -- We use one or the other consistently

pprSimplCount (VerySimplCount n) = ptext (sLit "Total ticks:") <+> int n
pprSimplCount (SimplCount { ticks = tks, details = dts, log1 = l1, log2 = l2 })
  = vcat [ptext (sLit "Total ticks:    ") <+> int tks,
          blankLine,
          pprTickCounts dts,
          if verboseSimplStats then
                vcat [blankLine,
                      ptext (sLit "Log (most recent first)"),
                      nest 4 (vcat (map ppr l1) $$ vcat (map ppr l2))]
          else Outputable.empty
    ]

pprTickCounts :: Map Tick Int -> SDoc
pprTickCounts counts
  = vcat (map pprTickGroup groups)
  where
    groups :: [[(Tick,Int)]]    -- Each group shares a comon tag
                                -- toList returns common tags adjacent
    groups = runs same_tag (Map.toList counts)
    same_tag (tick1,_) (tick2,_) = tickToTag tick1 == tickToTag tick2

pprTickGroup :: [(Tick, Int)] -> SDoc
pprTickGroup group@((tick1,_):_)
  = hang (int (sum [n | (_,n) <- group]) <+> text (tickString tick1))
       2 (vcat [ int n <+> pprTickCts tick
                                    -- flip as we want largest first
               | (tick,n) <- sortBy (flip (comparing snd)) group])
pprTickGroup [] = panic "pprTickGroup"

data Tick
  = PreInlineUnconditionally    Id
  | PostInlineUnconditionally   Id

  | UnfoldingDone               Id
  | RuleFired                   FastString      -- Rule name

  | LetFloatFromLet
  | EtaExpansion                Id      -- LHS binder
  | EtaReduction                Id      -- Binder on outer lambda
  | BetaReduction               Id      -- Lambda binder


  | CaseOfCase                  Id      -- Bndr on *inner* case
  | KnownBranch                 Id      -- Case binder
  | CaseMerge                   Id      -- Binder on outer case
  | AltMerge                    Id      -- Case binder
  | CaseElim                    Id      -- Case binder
  | CaseIdentity                Id      -- Case binder
  | FillInCaseDefault           Id      -- Case binder

  | BottomFound
  | SimplifierDone              -- Ticked at each iteration of the simplifier

instance Outputable Tick where
  ppr tick = text (tickString tick) <+> pprTickCts tick

instance Eq Tick where
  a == b = case a `cmpTick` b of
           EQ -> True
           _ -> False

instance Ord Tick where
  compare = cmpTick

tickToTag :: Tick -> Int
tickToTag (PreInlineUnconditionally _)  = 0
tickToTag (PostInlineUnconditionally _) = 1
tickToTag (UnfoldingDone _)             = 2
tickToTag (RuleFired _)                 = 3
tickToTag LetFloatFromLet               = 4
tickToTag (EtaExpansion _)              = 5
tickToTag (EtaReduction _)              = 6
tickToTag (BetaReduction _)             = 7
tickToTag (CaseOfCase _)                = 8
tickToTag (KnownBranch _)               = 9
tickToTag (CaseMerge _)                 = 10
tickToTag (CaseElim _)                  = 11
tickToTag (CaseIdentity _)              = 12
tickToTag (FillInCaseDefault _)         = 13
tickToTag BottomFound                   = 14
tickToTag SimplifierDone                = 16
tickToTag (AltMerge _)                  = 17

tickString :: Tick -> String
tickString (PreInlineUnconditionally _) = "PreInlineUnconditionally"
tickString (PostInlineUnconditionally _)= "PostInlineUnconditionally"
tickString (UnfoldingDone _)            = "UnfoldingDone"
tickString (RuleFired _)                = "RuleFired"
tickString LetFloatFromLet              = "LetFloatFromLet"
tickString (EtaExpansion _)             = "EtaExpansion"
tickString (EtaReduction _)             = "EtaReduction"
tickString (BetaReduction _)            = "BetaReduction"
tickString (CaseOfCase _)               = "CaseOfCase"
tickString (KnownBranch _)              = "KnownBranch"
tickString (CaseMerge _)                = "CaseMerge"
tickString (AltMerge _)                 = "AltMerge"
tickString (CaseElim _)                 = "CaseElim"
tickString (CaseIdentity _)             = "CaseIdentity"
tickString (FillInCaseDefault _)        = "FillInCaseDefault"
tickString BottomFound                  = "BottomFound"
tickString SimplifierDone               = "SimplifierDone"

pprTickCts :: Tick -> SDoc
pprTickCts (PreInlineUnconditionally v) = ppr v
pprTickCts (PostInlineUnconditionally v)= ppr v
pprTickCts (UnfoldingDone v)            = ppr v
pprTickCts (RuleFired v)                = ppr v
pprTickCts LetFloatFromLet              = Outputable.empty
pprTickCts (EtaExpansion v)             = ppr v
pprTickCts (EtaReduction v)             = ppr v
pprTickCts (BetaReduction v)            = ppr v
pprTickCts (CaseOfCase v)               = ppr v
pprTickCts (KnownBranch v)              = ppr v
pprTickCts (CaseMerge v)                = ppr v
pprTickCts (AltMerge v)                 = ppr v
pprTickCts (CaseElim v)                 = ppr v
pprTickCts (CaseIdentity v)             = ppr v
pprTickCts (FillInCaseDefault v)        = ppr v
pprTickCts _                            = Outputable.empty

cmpTick :: Tick -> Tick -> Ordering
cmpTick a b = case (tickToTag a `compare` tickToTag b) of
                GT -> GT
                EQ -> cmpEqTick a b
                LT -> LT

cmpEqTick :: Tick -> Tick -> Ordering
cmpEqTick (PreInlineUnconditionally a)  (PreInlineUnconditionally b)    = a `compare` b
cmpEqTick (PostInlineUnconditionally a) (PostInlineUnconditionally b)   = a `compare` b
cmpEqTick (UnfoldingDone a)             (UnfoldingDone b)               = a `compare` b
cmpEqTick (RuleFired a)                 (RuleFired b)                   = a `compare` b
cmpEqTick (EtaExpansion a)              (EtaExpansion b)                = a `compare` b
cmpEqTick (EtaReduction a)              (EtaReduction b)                = a `compare` b
cmpEqTick (BetaReduction a)             (BetaReduction b)               = a `compare` b
cmpEqTick (CaseOfCase a)                (CaseOfCase b)                  = a `compare` b
cmpEqTick (KnownBranch a)               (KnownBranch b)                 = a `compare` b
cmpEqTick (CaseMerge a)                 (CaseMerge b)                   = a `compare` b
cmpEqTick (AltMerge a)                  (AltMerge b)                    = a `compare` b
cmpEqTick (CaseElim a)                  (CaseElim b)                    = a `compare` b
cmpEqTick (CaseIdentity a)              (CaseIdentity b)                = a `compare` b
cmpEqTick (FillInCaseDefault a)         (FillInCaseDefault b)           = a `compare` b
cmpEqTick _                             _                               = EQ

{-
************************************************************************
*                                                                      *
             Monad and carried data structure definitions
*                                                                      *
************************************************************************
-}

newtype CoreState = CoreState {
        cs_uniq_supply :: UniqSupply
}

data CoreReader = CoreReader {
        cr_hsc_env :: HscEnv,
        cr_rule_base :: RuleBase,
        cr_module :: Module,
        cr_print_unqual :: PrintUnqualified,
#ifdef GHCI
        cr_globals :: (MVar PersistentLinkerState, Bool)
#else
        cr_globals :: ()
#endif
}

-- Note: CoreWriter used to be defined with data, rather than newtype.  If it
-- is defined that way again, the cw_simpl_count field, at least, must be
-- strict to avoid a space leak (Trac #7702).
newtype CoreWriter = CoreWriter {
        cw_simpl_count :: SimplCount
}

emptyWriter :: DynFlags -> CoreWriter
emptyWriter dflags = CoreWriter {
        cw_simpl_count = zeroSimplCount dflags
    }

plusWriter :: CoreWriter -> CoreWriter -> CoreWriter
plusWriter w1 w2 = CoreWriter {
        cw_simpl_count = (cw_simpl_count w1) `plusSimplCount` (cw_simpl_count w2)
    }

type CoreIOEnv = IOEnv CoreReader

-- | The monad used by Core-to-Core passes to access common state, register simplification
-- statistics and so on
newtype CoreM a = CoreM { unCoreM :: CoreState -> CoreIOEnv (a, CoreState, CoreWriter) }

instance Functor CoreM where
    fmap f ma = do
        a <- ma
        return (f a)

instance Monad CoreM where
    return x = CoreM (\s -> nop s x)
    mx >>= f = CoreM $ \s -> do
            (x, s', w1) <- unCoreM mx s
            (y, s'', w2) <- unCoreM (f x) s'
            let w = w1 `plusWriter` w2
            return $ seq w (y, s'', w)
            -- forcing w before building the tuple avoids a space leak
            -- (Trac #7702)
instance A.Applicative CoreM where
    pure = return
    (<*>) = ap
    (*>) = (>>)

instance MonadPlus IO => A.Alternative CoreM where
    empty = mzero
    (<|>) = mplus

-- For use if the user has imported Control.Monad.Error from MTL
-- Requires UndecidableInstances
instance MonadPlus IO => MonadPlus CoreM where
    mzero = CoreM (const mzero)
    m `mplus` n = CoreM (\rs -> unCoreM m rs `mplus` unCoreM n rs)

instance MonadUnique CoreM where
    getUniqueSupplyM = do
        us <- getS cs_uniq_supply
        let (us1, us2) = splitUniqSupply us
        modifyS (\s -> s { cs_uniq_supply = us2 })
        return us1

    getUniqueM = do
        us <- getS cs_uniq_supply
        let (u,us') = takeUniqFromSupply us
        modifyS (\s -> s { cs_uniq_supply = us' })
        return u

runCoreM :: HscEnv
         -> RuleBase
         -> UniqSupply
         -> Module
         -> PrintUnqualified
         -> CoreM a
         -> IO (a, SimplCount)
runCoreM hsc_env rule_base us mod print_unqual m = do
        glbls <- saveLinkerGlobals
        liftM extract $ runIOEnv (reader glbls) $ unCoreM m state
  where
    reader glbls = CoreReader {
            cr_hsc_env = hsc_env,
            cr_rule_base = rule_base,
            cr_module = mod,
            cr_globals = glbls,
            cr_print_unqual = print_unqual
        }
    state = CoreState {
            cs_uniq_supply = us
        }

    extract :: (a, CoreState, CoreWriter) -> (a, SimplCount)
    extract (value, _, writer) = (value, cw_simpl_count writer)

{-
************************************************************************
*                                                                      *
             Core combinators, not exported
*                                                                      *
************************************************************************
-}

nop :: CoreState -> a -> CoreIOEnv (a, CoreState, CoreWriter)
nop s x = do
    r <- getEnv
    return (x, s, emptyWriter $ (hsc_dflags . cr_hsc_env) r)

read :: (CoreReader -> a) -> CoreM a
read f = CoreM (\s -> getEnv >>= (\r -> nop s (f r)))

getS :: (CoreState -> a) -> CoreM a
getS f = CoreM (\s -> nop s (f s))

modifyS :: (CoreState -> CoreState) -> CoreM ()
modifyS f = CoreM (\s -> nop (f s) ())

write :: CoreWriter -> CoreM ()
write w = CoreM (\s -> return ((), s, w))

-- \subsection{Lifting IO into the monad}

-- | Lift an 'IOEnv' operation into 'CoreM'
liftIOEnv :: CoreIOEnv a -> CoreM a
liftIOEnv mx = CoreM (\s -> mx >>= (\x -> nop s x))

instance MonadIO CoreM where
    liftIO = liftIOEnv . IOEnv.liftIO

-- | Lift an 'IO' operation into 'CoreM' while consuming its 'SimplCount'
liftIOWithCount :: IO (SimplCount, a) -> CoreM a
liftIOWithCount what = liftIO what >>= (\(count, x) -> addSimplCount count >> return x)

{-
************************************************************************
*                                                                      *
             Reader, writer and state accessors
*                                                                      *
************************************************************************
-}

getHscEnv :: CoreM HscEnv
getHscEnv = read cr_hsc_env

getRuleBase :: CoreM RuleBase
getRuleBase = read cr_rule_base

getPrintUnqualified :: CoreM PrintUnqualified
getPrintUnqualified = read cr_print_unqual

addSimplCount :: SimplCount -> CoreM ()
addSimplCount count = write (CoreWriter { cw_simpl_count = count })

-- Convenience accessors for useful fields of HscEnv

instance HasDynFlags CoreM where
    getDynFlags = fmap hsc_dflags getHscEnv

instance HasModule CoreM where
    getModule = read cr_module

-- | The original name cache is the current mapping from 'Module' and
-- 'OccName' to a compiler-wide unique 'Name'
getOrigNameCache :: CoreM OrigNameCache
getOrigNameCache = do
    nameCacheRef <- fmap hsc_NC getHscEnv
    liftIO $ fmap nsNames $ readIORef nameCacheRef

getPackageFamInstEnv :: CoreM PackageFamInstEnv
getPackageFamInstEnv = do
    hsc_env <- getHscEnv
    eps <- liftIO $ hscEPS hsc_env
    return $ eps_fam_inst_env eps

{-
************************************************************************
*                                                                      *
             Initializing globals
*                                                                      *
************************************************************************

This is a rather annoying function. When a plugin is loaded, it currently
gets linked against a *newly loaded* copy of the GHC package. This would
not be a problem, except that the new copy has its own mutable state
that is not shared with that state that has already been initialized by
the original GHC package.

(NB This mechanism is sufficient for granting plugins read-only access to
globals that are guaranteed to be initialized before the plugin is loaded.  If
any further synchronization is necessary, I would suggest using the more
sophisticated mechanism involving GHC.Conc.Sync.sharedCAF and rts/Globals.c to
share a single instance of the global variable among the compiler and the
plugins.  Perhaps we should migrate all global variables to use that mechanism,
for robustness... -- NSF July 2013)

This leads to loaded plugins calling GHC code which pokes the static flags,
and then dying with a panic because the static flags *it* sees are uninitialized.

There are two possible solutions:
  1. Export the symbols from the GHC executable from the GHC library and link
     against this existing copy rather than a new copy of the GHC library
  2. Carefully ensure that the global state in the two copies of the GHC
     library matches

I tried 1. and it *almost* works (and speeds up plugin load times!) except
on Windows. On Windows the GHC library tends to export more than 65536 symbols
(see #5292) which overflows the limit of what we can export from the EXE and
causes breakage.

(Note that if the GHC executable was dynamically linked this wouldn't be a
problem, because we could share the GHC library it links to.)

We are going to try 2. instead. Unfortunately, this means that every plugin
will have to say `reinitializeGlobals` before it does anything, but never mind.

I've threaded the cr_globals through CoreM rather than giving them as an
argument to the plugin function so that we can turn this function into
(return ()) without breaking any plugins when we eventually get 1. working.
-}

reinitializeGlobals :: CoreM ()
reinitializeGlobals = do
    linker_globals <- read cr_globals
    hsc_env <- getHscEnv
    let dflags = hsc_dflags hsc_env
    liftIO $ restoreLinkerGlobals linker_globals
    liftIO $ setUnsafeGlobalDynFlags dflags

{-
************************************************************************
*                                                                      *
             Dealing with annotations
*                                                                      *
************************************************************************
-}

-- | Get all annotations of a given type. This happens lazily, that is
-- no deserialization will take place until the [a] is actually demanded and
-- the [a] can also be empty (the UniqFM is not filtered).
--
-- This should be done once at the start of a Core-to-Core pass that uses
-- annotations.
--
-- See Note [Annotations]
getAnnotations :: Typeable a => ([Word8] -> a) -> ModGuts -> CoreM (UniqFM [a])
getAnnotations deserialize guts = do
     hsc_env <- getHscEnv
     ann_env <- liftIO $ prepareAnnotations hsc_env (Just guts)
     return (deserializeAnns deserialize ann_env)

-- | Get at most one annotation of a given type per Unique.
getFirstAnnotations :: Typeable a => ([Word8] -> a) -> ModGuts -> CoreM (UniqFM a)
getFirstAnnotations deserialize guts
  = liftM (mapUFM head . filterUFM (not . null))
  $ getAnnotations deserialize guts

{-
Note [Annotations]
~~~~~~~~~~~~~~~~~~
A Core-to-Core pass that wants to make use of annotations calls
getAnnotations or getFirstAnnotations at the beginning to obtain a UniqFM with
annotations of a specific type. This produces all annotations from interface
files read so far. However, annotations from interface files read during the
pass will not be visible until getAnnotations is called again. This is similar
to how rules work and probably isn't too bad.

The current implementation could be optimised a bit: when looking up
annotations for a thing from the HomePackageTable, we could search directly in
the module where the thing is defined rather than building one UniqFM which
contains all annotations we know of. This would work because annotations can
only be given to things defined in the same module. However, since we would
only want to deserialise every annotation once, we would have to build a cache
for every module in the HTP. In the end, it's probably not worth it as long as
we aren't using annotations heavily.

************************************************************************
*                                                                      *
                Direct screen output
*                                                                      *
************************************************************************
-}

msg :: (DynFlags -> SDoc -> IO ()) -> SDoc -> CoreM ()
msg how doc = do
        dflags <- getDynFlags
        liftIO $ how dflags doc

-- | Output a String message to the screen
putMsgS :: String -> CoreM ()
putMsgS = putMsg . text

-- | Output a message to the screen
putMsg :: SDoc -> CoreM ()
putMsg = msg Err.putMsg

-- | Output a string error to the screen
errorMsgS :: String -> CoreM ()
errorMsgS = errorMsg . text

-- | Output an error to the screen
errorMsg :: SDoc -> CoreM ()
errorMsg = msg Err.errorMsg

-- | Output a fatal string error to the screen. Note this does not by itself cause the compiler to die
fatalErrorMsgS :: String -> CoreM ()
fatalErrorMsgS = fatalErrorMsg . text

-- | Output a fatal error to the screen. Note this does not by itself cause the compiler to die
fatalErrorMsg :: SDoc -> CoreM ()
fatalErrorMsg = msg Err.fatalErrorMsg

-- | Output a string debugging message at verbosity level of @-v@ or higher
debugTraceMsgS :: String -> CoreM ()
debugTraceMsgS = debugTraceMsg . text

-- | Outputs a debugging message at verbosity level of @-v@ or higher
debugTraceMsg :: SDoc -> CoreM ()
debugTraceMsg = msg (flip Err.debugTraceMsg 3)

-- | Show some labelled 'SDoc' if a particular flag is set or at a verbosity level of @-v -ddump-most@ or higher
dumpIfSet_dyn :: DumpFlag -> String -> SDoc -> CoreM ()
dumpIfSet_dyn flag str = msg (\dflags -> Err.dumpIfSet_dyn dflags flag str)

{-
************************************************************************
*                                                                      *
               Finding TyThings
*                                                                      *
************************************************************************
-}

instance MonadThings CoreM where
    lookupThing name = do
        hsc_env <- getHscEnv
        liftIO $ initTcForLookup hsc_env (tcLookupGlobal name)

{-
************************************************************************
*                                                                      *
               Template Haskell interoperability
*                                                                      *
************************************************************************
-}

#ifdef GHCI
-- | Attempt to convert a Template Haskell name to one that GHC can
-- understand. Original TH names such as those you get when you use
-- the @'foo@ syntax will be translated to their equivalent GHC name
-- exactly. Qualified or unqualifed TH names will be dynamically bound
-- to names in the module being compiled, if possible. Exact TH names
-- will be bound to the name they represent, exactly.
thNameToGhcName :: TH.Name -> CoreM (Maybe Name)
thNameToGhcName th_name = do
    hsc_env <- getHscEnv
    liftIO $ initTcForLookup hsc_env (lookupThName_maybe th_name)
#endif
