simplCore/CoreMonad.lhs

% % (c) The AQUA Project, Glasgow University, 1993-1998 % \section[CoreMonad]{The core pipeline monad} \begin{code}

    {-# 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

\end{code} %************************************************************************ %* * Debug output %* * %************************************************************************ These functions are not CoreM monad stuff, but they probably ought to be, and it makes a conveneint place. place for them. They print out stuff before and after core passes, and do Core Lint when necessary. \begin{code}

    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)

\end{code} %************************************************************************ %* * The CoreToDo type and related types Abstraction of core-to-core passes to run. %* * %************************************************************************ \begin{code}

    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

\end{code} \begin{code}

    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

\end{code} \begin{code}

    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

\end{code} \begin{code}

    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

\end{code} 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 %* * %************************************************************************ \begin{code}

    -- | 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' }) }

\end{code} %************************************************************************ %* * Counting and logging %* * %************************************************************************ \begin{code}

    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

\end{code} \begin{code}

    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"

\end{code} \begin{code}

    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

\end{code} %************************************************************************ %* * Monad and carried data structure definitions %* * %************************************************************************ \begin{code}

    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)

\end{code} %************************************************************************ %* * Core combinators, not exported %* * %************************************************************************ \begin{code}

    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))

\end{code} \subsection{Lifting IO into the monad} \begin{code}

    -- | 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)

\end{code} %************************************************************************ %* * Reader, writer and state accessors %* * %************************************************************************ \begin{code}

    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

\end{code} %************************************************************************ %* * 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 exeecutable 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. \begin{code}

    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

\end{code} %************************************************************************ %* * Dealing with annotations %* * %************************************************************************ \begin{code}

    -- | 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

\end{code} 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 %* * %************************************************************************ \begin{code}

    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)

\end{code} %************************************************************************ %* * Finding TyThings %* * %************************************************************************ \begin{code}

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

\end{code} %************************************************************************ %* * Template Haskell interoperability %* * %************************************************************************ \begin{code}

    #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

\end{code}