path: root/compiler/simplCore/CoreMonad.lhs

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

\begin{code}
{-# LANGUAGE UndecidableInstances #-}

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

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

    -- * The monad
    CoreM, runCoreM,
    
    -- ** Reading from the monad
    getHscEnv, getRuleBase, getModule,
    getDynFlags, getOrigNameCache,
    
    -- ** Writing to the monad
    addSimplCount,
    
    -- ** Lifting into the monad
    liftIO, liftIOWithCount,
    liftIO1, liftIO2, liftIO3, liftIO4,
    
    -- ** Dealing with annotations
    getAnnotations, getFirstAnnotations,
    
    -- ** Debug output
    showPass, endPass, endIteration, 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 )
import PrelNames        ( iNTERACTIVE )
import HscTypes
import Module           ( Module )
import DynFlags
import StaticFlags	
import Rules            ( RuleBase )
import BasicTypes       ( CompilerPhase(..) )
import Annotations
import Id		( Id )

import IOEnv hiding     ( liftIO, failM, failWithM )
import qualified IOEnv  ( liftIO )
import TcEnv            ( tcLookupGlobal )
import TcRnMonad        ( TcM, initTc )

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

import Util		( split )
import Data.List	( intersperse )
import Data.Dynamic
import Data.IORef
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Word
import Control.Monad

import Prelude hiding   ( read )

#ifdef GHCI
import {-# SOURCE #-} TcSplice ( lookupThName_maybe )
import qualified Language.Haskell.TH as TH
#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 (showSDoc (ppr pass))

endPass :: DynFlags -> CoreToDo -> [CoreBind] -> [CoreRule] -> IO ()
endPass dflags pass = dumpAndLint dflags True pass empty (coreDumpFlag pass)

-- Same as endPass but doesn't dump Core even with -dverbose-core2core
endIteration :: DynFlags -> CoreToDo -> Int -> [CoreBind] -> [CoreRule] -> IO ()
endIteration dflags pass n
  = dumpAndLint dflags False pass (ptext (sLit "iteration=") <> int n)
                (Just Opt_D_dump_simpl_iterations)

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

dumpAndLint :: DynFlags -> Bool -> CoreToDo -> SDoc -> Maybe DynFlag
            -> [CoreBind] -> [CoreRule] -> IO ()
-- The "show_all" parameter says to print dump if -dverbose-core2core is on
dumpAndLint dflags show_all pass extra_info mb_dump_flag binds rules
  = do {  -- Report result size if required
	  -- This has the side effect of forcing the intermediate to be evaluated
       ; Err.debugTraceMsg dflags 2 $
		(text "    Result size =" <+> int (coreBindsSize binds))

	-- Report verbosely, if required
       ; let pass_name = showSDoc (ppr pass <+> extra_info)
             dump_doc  = pprCoreBindings binds 
                         $$ ppUnless (null rules) pp_rules

       ; case mb_dump_flag of
            Nothing        -> return ()
            Just dump_flag -> Err.dumpIfSet_dyn_or dflags dump_flags pass_name dump_doc
               where
                 dump_flags | show_all  = [dump_flag, Opt_D_verbose_core2core]
		 	    | otherwise = [dump_flag] 

	-- Type check
       ; when (dopt Opt_DoCoreLinting dflags) $
         do { let (warns, errs) = lintCoreBindings binds
            ; Err.showPass dflags ("Core Linted result of " ++ pass_name)
            ; displayLintResults dflags pass warns errs binds  } }
  where
    pp_rules = vcat [ blankLine
                    , ptext (sLit "------ Local rules for imported ids --------")
                    , pprRules rules ]

displayLintResults :: DynFlags -> CoreToDo
                   -> Bag Err.Message -> Bag Err.Message -> [CoreBind]
                   -> IO ()
displayLintResults dflags pass warns errs binds
  | not (isEmptyBag errs)
  = do { printDump (vcat [ banner "errors", 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
  = printDump (banner "warnings" $$ Err.pprMessageBag warns)

  | otherwise = return ()
  where
    banner string = ptext (sLit "*** Core Lint")      <+> text string 
                    <+> ptext (sLit ": in result of") <+> ppr 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
\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

  | CoreDoFloatInwards
  | CoreDoFloatOutwards FloatOutSwitches
  | CoreLiberateCase
  | CoreDoPrintCore
  | CoreDoStaticArgs
  | CoreDoStrictness
  | CoreDoWorkerWrapper
  | CoreDoSpecialising
  | CoreDoSpecConstr
  | CoreDoGlomBinds
  | 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	 -- Not strictly a core-to-core pass, but produces
                 -- Core output, and hence useful to pass to endPass

  | CoreTidy
  | CorePrep

coreDumpFlag :: CoreToDo -> Maybe DynFlag
coreDumpFlag (CoreDoSimplify {})      = Just Opt_D_dump_simpl_phases
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 CoreTidy                 = Just Opt_D_dump_simpl
coreDumpFlag CorePrep                 = Just Opt_D_dump_prep

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

instance Outputable CoreToDo where
  ppr (CoreDoSimplify n md)  = ptext (sLit "Simplifier")
                               <+> ppr md
                                 <+> ptext (sLit "max-iterations=") <> int n
  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")
  ppr CoreTidy                 = ptext (sLit "Tidy Core")
  ppr CorePrep 		       = ptext (sLit "CorePrep")
  ppr CoreDoPrintCore          = ptext (sLit "Print core")
  ppr (CoreDoRuleCheck {})     = ptext (sLit "Rule check")
  ppr CoreDoGlomBinds          = ptext (sLit "Glom binds")
  ppr CoreDoNothing            = ptext (sLit "CoreDoNothing")
  ppr (CoreDoPasses {})        = ptext (sLit "CoreDoPasses")
\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) ])
\end{code}


%************************************************************************
%*									*
           Generating the main optimisation pipeline
%*									*
%************************************************************************

\begin{code}
getCoreToDo :: DynFlags -> [CoreToDo]
getCoreToDo dflags
  = core_todo
  where
    opt_level     = optLevel           dflags
    phases        = simplPhases        dflags
    max_iter      = maxSimplIterations dflags
    rule_check    = ruleCheck          dflags
    strictness    = dopt Opt_Strictness   		  dflags
    full_laziness = dopt Opt_FullLaziness 		  dflags
    do_specialise = dopt Opt_Specialise   		  dflags
    do_float_in   = dopt Opt_FloatIn      		  dflags          
    cse           = dopt Opt_CSE                          dflags
    spec_constr   = dopt Opt_SpecConstr                   dflags
    liberate_case = dopt Opt_LiberateCase                 dflags
    static_args   = dopt Opt_StaticArgumentTransformation dflags
    rules_on      = dopt Opt_EnableRewriteRules           dflags
    eta_expand_on = dopt Opt_DoLambdaEtaExpansion         dflags

    maybe_rule_check phase = runMaybe rule_check (CoreDoRuleCheck phase)

    maybe_strictness_before phase
      = runWhen (phase `elem` strictnessBefore dflags) CoreDoStrictness

    base_mode = SimplMode { sm_phase      = panic "base_mode"
                          , sm_names      = []
                          , sm_rules      = rules_on
                          , sm_eta_expand = eta_expand_on
                          , sm_inline     = True
                          , sm_case_case  = True }

    simpl_phase phase names iter
      = CoreDoPasses
      $   [ maybe_strictness_before phase
          , CoreDoSimplify iter
                (base_mode { sm_phase = Phase phase
                           , sm_names = names })

          , maybe_rule_check (Phase phase) ]

          -- Vectorisation can introduce a fair few common sub expressions involving 
          --  DPH primitives. For example, see the Reverse test from dph-examples.
          --  We need to eliminate these common sub expressions before their definitions
          --  are inlined in phase 2. The CSE introduces lots of  v1 = v2 bindings, 
          --  so we also run simpl_gently to inline them.
      ++  (if dopt Opt_Vectorise dflags && phase == 3
	    then [CoreCSE, simpl_gently]
	    else [])

    vectorisation
      = runWhen (dopt Opt_Vectorise dflags) $
          CoreDoPasses [ simpl_gently, CoreDoVectorisation ]

                -- By default, we have 2 phases before phase 0.

                -- Want to run with inline phase 2 after the specialiser to give
                -- maximum chance for fusion to work before we inline build/augment
                -- in phase 1.  This made a difference in 'ansi' where an
                -- overloaded function wasn't inlined till too late.

                -- Need phase 1 so that build/augment get
                -- inlined.  I found that spectral/hartel/genfft lost some useful
                -- strictness in the function sumcode' if augment is not inlined
                -- before strictness analysis runs
    simpl_phases = CoreDoPasses [ simpl_phase phase ["main"] max_iter
                                | phase <- [phases, phases-1 .. 1] ]


        -- initial simplify: mk specialiser happy: minimum effort please
    simpl_gently = CoreDoSimplify max_iter
                       (base_mode { sm_phase = InitialPhase
                                  , sm_names = ["Gentle"]
                                  , sm_rules = rules_on   -- Note [RULEs enabled in SimplGently]
                                  , sm_inline = False
                                  , sm_case_case = False })
                          -- Don't do case-of-case transformations.
                          -- This makes full laziness work better

    core_todo =
     if opt_level == 0 then
       [vectorisation,
        simpl_phase 0 ["final"] max_iter]
     else {- opt_level >= 1 -} [

    -- We want to do the static argument transform before full laziness as it
    -- may expose extra opportunities to float things outwards. However, to fix
    -- up the output of the transformation we need at do at least one simplify
    -- after this before anything else
        runWhen static_args (CoreDoPasses [ simpl_gently, CoreDoStaticArgs ]),

        -- We run vectorisation here for now, but we might also try to run
        -- it later
        vectorisation,

        -- initial simplify: mk specialiser happy: minimum effort please
        simpl_gently,

        -- Specialisation is best done before full laziness
        -- so that overloaded functions have all their dictionary lambdas manifest
        runWhen do_specialise CoreDoSpecialising,

        runWhen full_laziness $
           CoreDoFloatOutwards FloatOutSwitches {
                                 floatOutLambdas   = Just 0,
                                 floatOutConstants = True,
                                 floatOutPartialApplications = False },
      		-- Was: gentleFloatOutSwitches	
                --
		-- I have no idea why, but not floating constants to
		-- top level is very bad in some cases.
                --
		-- Notably: p_ident in spectral/rewrite
		-- 	    Changing from "gentle" to "constantsOnly"
		-- 	    improved rewrite's allocation by 19%, and
		-- 	    made 0.0% difference to any other nofib
		-- 	    benchmark
                --
                -- Not doing floatOutPartialApplications yet, we'll do
                -- that later on when we've had a chance to get more
                -- accurate arity information.  In fact it makes no
                -- difference at all to performance if we do it here,
                -- but maybe we save some unnecessary to-and-fro in
                -- the simplifier.

        runWhen do_float_in CoreDoFloatInwards,

        simpl_phases,

                -- Phase 0: allow all Ids to be inlined now
                -- This gets foldr inlined before strictness analysis

                -- At least 3 iterations because otherwise we land up with
                -- huge dead expressions because of an infelicity in the
                -- simpifier.
                --      let k = BIG in foldr k z xs
                -- ==>  let k = BIG in letrec go = \xs -> ...(k x).... in go xs
                -- ==>  let k = BIG in letrec go = \xs -> ...(BIG x).... in go xs
                -- Don't stop now!
        simpl_phase 0 ["main"] (max max_iter 3),

        runWhen strictness (CoreDoPasses [
                CoreDoStrictness,
                CoreDoWorkerWrapper,
                CoreDoGlomBinds,
                simpl_phase 0 ["post-worker-wrapper"] max_iter
                ]),

        runWhen full_laziness $
           CoreDoFloatOutwards FloatOutSwitches {
                                 floatOutLambdas   = floatLamArgs dflags,
                                 floatOutConstants = True,
                                 floatOutPartialApplications = True },
                -- nofib/spectral/hartel/wang doubles in speed if you
                -- do full laziness late in the day.  It only happens
                -- after fusion and other stuff, so the early pass doesn't
                -- catch it.  For the record, the redex is
                --        f_el22 (f_el21 r_midblock)


        runWhen cse CoreCSE,
                -- We want CSE to follow the final full-laziness pass, because it may
                -- succeed in commoning up things floated out by full laziness.
                -- CSE used to rely on the no-shadowing invariant, but it doesn't any more

        runWhen do_float_in CoreDoFloatInwards,

        maybe_rule_check (Phase 0),

                -- Case-liberation for -O2.  This should be after
                -- strictness analysis and the simplification which follows it.
        runWhen liberate_case (CoreDoPasses [
            CoreLiberateCase,
            simpl_phase 0 ["post-liberate-case"] max_iter
            ]),         -- Run the simplifier after LiberateCase to vastly
                        -- reduce the possiblility of shadowing
                        -- Reason: see Note [Shadowing] in SpecConstr.lhs

        runWhen spec_constr CoreDoSpecConstr,

        maybe_rule_check (Phase 0),

        -- Final clean-up simplification:
        simpl_phase 0 ["final"] max_iter
     ]

-- 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.


%************************************************************************
%*									*
             Counting and logging
%*									*
%************************************************************************

\begin{code}
verboseSimplStats :: Bool
verboseSimplStats = opt_PprStyle_Debug		-- For now, anyway

zeroSimplCount	   :: DynFlags -> SimplCount
isZeroSimplCount   :: SimplCount -> Bool
pprSimplCount	   :: SimplCount -> SDoc
doSimplTick, 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

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

doSimplTick tick sc@SimplCount { ticks = tks, details = dts, n_log = nl, log1 = l1 }
  | nl >= opt_HistorySize = 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 (Map.toList 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 :: [(Tick,Int)] -> SDoc
pprTickCounts [] = empty
pprTickCounts ((tick1,n1):ticks)
  = vcat [int tot_n <+> text (tickString tick1),
	  pprTCDetails real_these,
	  pprTickCounts others
    ]
  where
    tick1_tag		= tickToTag tick1
    (these, others)	= span same_tick ticks
    real_these		= (tick1,n1):these
    same_tick (tick2,_) = tickToTag tick2 == tick1_tag
    tot_n		= sum [n | (_,n) <- real_these]

pprTCDetails :: [(Tick, Int)] -> SDoc
pprTCDetails ticks
  = nest 4 (vcat [int n <+> pprTickCts tick | (tick,n) <- ticks])
\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
}

data 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'
            return (y, s'', w1 `plusWriter` w2)

instance Applicative CoreM where
    pure = return
    (<*>) = ap

-- 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

runCoreM :: HscEnv
         -> RuleBase
         -> UniqSupply
         -> Module
         -> CoreM a
         -> IO (a, SimplCount)
runCoreM hsc_env rule_base us mod m =
        liftM extract $ runIOEnv reader $ unCoreM m state
  where
    reader = CoreReader {
            cr_hsc_env = hsc_env,
            cr_rule_base = rule_base,
            cr_module = mod
        }
    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

getModule :: CoreM Module
getModule = read cr_module

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

-- Convenience accessors for useful fields of HscEnv

getDynFlags :: CoreM DynFlags
getDynFlags = fmap hsc_dflags getHscEnv

-- | 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

\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 :: DynFlag -> String -> SDoc -> CoreM ()
dumpIfSet_dyn flag str = msg (\dflags -> Err.dumpIfSet_dyn dflags flag str)
\end{code}

\begin{code}

initTcForLookup :: HscEnv -> TcM a -> IO a
initTcForLookup hsc_env = liftM (expectJust "initTcInteractive" . snd) . initTc hsc_env HsSrcFile False iNTERACTIVE

\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}