{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
--     http://ghc.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

{-# LANGUAGE UndecidableInstances #-}

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

    -- * Plugins
    PluginPass, Plugin(..), CommandLineOption, 
    defaultPlugin, 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,
    
    -- ** Writing to the monad
    addSimplCount,
    
    -- ** Lifting into the monad
    liftIO, liftIOWithCount,
    liftIO1, liftIO2, liftIO3, liftIO4,
    
    -- ** Global initialization
    reinitializeGlobals,
    
    -- ** Dealing with annotations
    getAnnotations, getFirstAnnotations,
    
    -- ** Debug output
    showPass, endPass, dumpPassResult, lintPassResult, 
    lintInteractiveExpr, dumpIfSet,

    -- ** 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 PprCore
import CoreUtils
import CoreLint		( lintCoreBindings, lintExpr )
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 InstEnv          ( instanceDFunId )
import Type             ( tyVarsOfType )
import Id               ( idType )
import Var
import VarSet

import Outputable
import FastString
import qualified ErrUtils as Err
import Bag
import Maybes
import SrcLoc
import UniqSupply
import UniqFM       ( UniqFM, mapUFM, filterUFM )
import MonadUtils

import Util ( split )
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

showPass :: DynFlags -> CoreToDo -> IO ()
showPass dflags pass = Err.showPass dflags (showPpr dflags pass)

endPass :: HscEnv -> CoreToDo -> CoreProgram -> [CoreRule] -> IO ()
endPass hsc_env pass binds rules
  = do { dumpPassResult dflags mb_flag (ppr pass) (pprPassDetails pass) binds rules
       ; lintPassResult hsc_env pass binds }      
  where
    dflags = hsc_dflags hsc_env 
    mb_flag = case coreDumpFlag pass of
                Just flag | dopt flag dflags                    -> Just flag
                          | dopt Opt_D_verbose_core2core dflags -> Just flag
                _ -> Nothing

dumpIfSet :: DynFlags -> Bool -> CoreToDo -> SDoc -> SDoc -> IO ()
dumpIfSet dflags dump_me pass extra_info doc
  = Err.dumpIfSet dflags dump_me (showSDoc dflags (ppr pass <+> extra_info)) doc

dumpPassResult :: DynFlags 
               -> Maybe DumpFlag		-- Just df => show details in a file whose
	       	  			--            name is specified by df
               -> SDoc 			-- Header
               -> SDoc 			-- Extra info to appear after header
               -> CoreProgram -> [CoreRule] 
               -> IO ()
dumpPassResult dflags mb_flag hdr extra_info binds rules
  | Just flag <- mb_flag
  = Err.dumpSDoc dflags flag (showSDoc dflags hdr) dump_doc

  | otherwise
  = Err.debugTraceMsg dflags 2 size_doc
          -- Report result size 
	  -- This has the side effect of forcing the intermediate to be evaluated

  where
    size_doc = sep [text "Result size of" <+> hdr, nest 2 (equals <+> ppr (coreBindsStats binds))]

    dump_doc  = vcat [ nest 2 extra_info
		     , size_doc
                     , blankLine
                     , pprCoreBindings binds 
                     , ppUnless (null rules) pp_rules ]
    pp_rules = vcat [ blankLine
                    , ptext (sLit "------ Local rules for imported ids --------")
                    , pprRules rules ]

lintPassResult :: HscEnv -> CoreToDo -> CoreProgram -> IO ()
lintPassResult hsc_env pass binds
  | not (gopt Opt_DoCoreLinting dflags)
  = return ()
  | otherwise
  = do { let (warns, errs) = lintCoreBindings (interactiveInScope hsc_env) binds
       ; Err.showPass dflags ("Core Linted result of " ++ showPpr dflags pass)
       ; displayLintResults dflags pass warns errs binds  }
  where 
    dflags = hsc_dflags hsc_env

displayLintResults :: DynFlags -> CoreToDo
                   -> Bag Err.MsgDoc -> Bag Err.MsgDoc -> CoreProgram
                   -> IO ()
displayLintResults dflags pass warns errs binds
  | not (isEmptyBag errs)
  = do { log_action dflags dflags Err.SevDump noSrcSpan defaultDumpStyle
           (vcat [ lint_banner "errors" (ppr pass), Err.pprMessageBag errs
                 , ptext (sLit "*** Offending Program ***")
                 , pprCoreBindings binds
                 , ptext (sLit "*** End of Offense ***") ])
       ; Err.ghcExit dflags 1 }

  | not (isEmptyBag warns)
  , not (case pass of { CoreDesugar -> True; _ -> False })
    	-- Suppress warnings after desugaring pass because some
	-- are legitimate. Notably, the desugarer generates instance
	-- methods with INLINE pragmas that form a mutually recursive
	-- group.  Only afer a round of simplification are they unravelled.
  , not opt_NoDebugOutput
  , showLintWarnings pass
  = log_action dflags dflags Err.SevDump noSrcSpan defaultDumpStyle
        (lint_banner "warnings" (ppr pass) $$ Err.pprMessageBag warns)

  | otherwise = return ()
  where

lint_banner :: String -> SDoc -> SDoc
lint_banner string pass = ptext (sLit "*** Core Lint")      <+> text string 
                          <+> ptext (sLit ": in result of") <+> pass
                          <+> ptext (sLit "***")

showLintWarnings :: CoreToDo -> Bool
-- Disable Lint warnings on the first simplifier pass, because
-- there may be some INLINE knots still tied, which is tiresomely noisy
showLintWarnings (CoreDoSimplify _ (SimplMode { sm_phase = InitialPhase })) = False
showLintWarnings _ = True

lintInteractiveExpr :: String -> HscEnv -> CoreExpr -> IO ()
lintInteractiveExpr what hsc_env expr
  | not (gopt Opt_DoCoreLinting dflags)
  = return ()
  | Just err <- lintExpr (interactiveInScope hsc_env) expr 
  = do { display_lint_err err
       ; Err.ghcExit dflags 1 }
  | otherwise
  = return ()
  where
    dflags = hsc_dflags hsc_env

    display_lint_err err
      = do { log_action dflags dflags Err.SevDump noSrcSpan defaultDumpStyle
               (vcat [ lint_banner "errors" (text what) 
                     , err
                     , ptext (sLit "*** Offending Program ***")
                     , pprCoreExpr expr
                     , ptext (sLit "*** End of Offense ***") ])
           ; Err.ghcExit dflags 1 }

interactiveInScope :: HscEnv -> [Var]
-- In GHCi we may lint expressions, or bindings arising from 'deriving'
-- clauses, that mention variables bound in the interactive context.
-- These are Local things (see Note [Interactively-bound Ids in GHCi] in HscTypes).
-- So we have to tell Lint about them, lest it reports them as out of scope.
-- 
-- We do this by find local-named things that may appear free in interactive
-- context.  This function is pretty revolting and quite possibly not quite right.
-- When we are not in GHCi, the interactive context (hsc_IC hsc_env) is empty
-- so this is a (cheap) no-op.
-- 
-- See Trac #8215 for an example
interactiveInScope hsc_env 
  = varSetElems tyvars ++ ids
  where
    -- C.f. TcRnDriver.setInteractiveContext, Desugar.deSugarExpr
    ictxt                   = hsc_IC hsc_env
    (cls_insts, _fam_insts) = ic_instances ictxt
    te1    = mkTypeEnvWithImplicits (ic_tythings ictxt)
    te     = extendTypeEnvWithIds te1 (map instanceDFunId cls_insts)
    ids    = typeEnvIds te
    tyvars = foldr (unionVarSet . tyVarsOfType . idType) emptyVarSet ids
              -- Why the type variables?  How can the top level envt have free tyvars?
              -- I think it's because of the GHCi debugger, which can bind variables
              --   f :: [t] -> [t]
              -- where t is a RuntimeUnk (see TcType)

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
  | 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

coreDumpFlag :: CoreToDo -> Maybe DumpFlag
coreDumpFlag (CoreDoSimplify {})      = Just Opt_D_dump_simpl_phases
coreDumpFlag (CoreDoPluginPass {})    = Just Opt_D_dump_core_pipeline
coreDumpFlag CoreDoFloatInwards       = Just Opt_D_verbose_core2core
coreDumpFlag (CoreDoFloatOutwards {}) = Just Opt_D_verbose_core2core
coreDumpFlag CoreLiberateCase         = Just Opt_D_verbose_core2core
coreDumpFlag CoreDoStaticArgs 	      = Just Opt_D_verbose_core2core
coreDumpFlag CoreDoStrictness 	      = Just Opt_D_dump_stranal
coreDumpFlag CoreDoWorkerWrapper      = Just Opt_D_dump_worker_wrapper
coreDumpFlag CoreDoSpecialising       = Just Opt_D_dump_spec
coreDumpFlag CoreDoSpecConstr         = Just Opt_D_dump_spec
coreDumpFlag CoreCSE                  = Just Opt_D_dump_cse 
coreDumpFlag CoreDoVectorisation      = Just Opt_D_dump_vect
coreDumpFlag CoreDesugar              = Just Opt_D_dump_ds 
coreDumpFlag CoreDesugarOpt           = Just Opt_D_dump_ds 
coreDumpFlag CoreTidy                 = Just Opt_D_dump_simpl
coreDumpFlag CorePrep                 = Just Opt_D_dump_prep

coreDumpFlag CoreDoPrintCore         = Nothing
coreDumpFlag (CoreDoRuleCheck {})    = Nothing
coreDumpFlag CoreDoNothing           = Nothing
coreDumpFlag (CoreDoPasses {})       = Nothing

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 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 _ = 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
  floatOutPartialApplications :: Bool -- ^ True <=> float out partial applications
                                            --            based on arity information.
  }
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 "PAPs =")   <+> ppr (floatOutPartialApplications 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


dumpSimplPhase :: DynFlags -> SimplifierMode -> Bool
dumpSimplPhase dflags mode
   | Just spec_string <- shouldDumpSimplPhase dflags
   = match_spec spec_string
   | otherwise
   = dopt Opt_D_verbose_core2core dflags

  where
    match_spec :: String -> Bool
    match_spec spec_string 
      = or $ map (and . map match . split ':') 
           $ split ',' spec_string

    match :: String -> Bool
    match "" = True
    match s  = case reads s of
                [(n,"")] -> phase_num  n
                _        -> phase_name s

    phase_num :: Int -> Bool
    phase_num n = case sm_phase mode of
                    Phase k -> n == k
                    _       -> False

    phase_name :: String -> Bool
    phase_name s = s `elem` sm_names mode

-- | Command line options gathered from the -PModule.Name:stuff syntax are given to you as this type
type CommandLineOption = String

-- | 'Plugin' is the core compiler plugin data type. Try to avoid
-- constructing one of these directly, and just modify some fields of
-- 'defaultPlugin' instead: this is to try and preserve source-code
-- compatability when we add fields to this.
--
-- Nonetheless, this API is preliminary and highly likely to change in the future.
data Plugin = Plugin { 
        installCoreToDos :: [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo]
                -- ^ Modify the Core pipeline that will be used for compilation. 
                -- This is called as the Core pipeline is built for every module
                --  being compiled, and plugins get the opportunity to modify 
                -- the pipeline in a nondeterministic order.
     }

-- | Default plugin: does nothing at all! For compatability reasons you should base all your
-- plugin definitions on this default value.
defaultPlugin :: Plugin
defaultPlugin = Plugin {
        installCoreToDos = const return
    }

-- | 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' }) }

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 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		= 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 _    			= 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

newtype CoreState = CoreState {
        cs_uniq_supply :: UniqSupply
}

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

data CoreWriter = CoreWriter {
        cw_simpl_count :: !SimplCount  
        -- Making this strict fixes a nasty space leak
        -- See Trac #7702
}

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 -- forcing w before returning avoids a space leak (Trac #7702)
            return $ seq w (y, s'', w)

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
         -> CoreM a
         -> IO (a, SimplCount)
runCoreM hsc_env rule_base us mod 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
        }
    state = CoreState { 
            cs_uniq_supply = us
        }

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

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))

-- | 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)

getHscEnv :: CoreM HscEnv
getHscEnv = read cr_hsc_env

getRuleBase :: CoreM RuleBase
getRuleBase = read cr_rule_base

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

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

-- | 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
  

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)

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

#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