%
-% (c) The AQUA Project, Glasgow University, 1993-1996
+% (c) The AQUA Project, Glasgow University, 1993-1998
%
\section[SimplMonad]{The simplifier Monad}
\begin{code}
-#include "HsVersions.h"
-
module SimplMonad (
- SmplM(..),
+ InId, InBind, InExpr, InAlt, InArg, InType, InBinder,
+ OutId, OutTyVar, OutBind, OutExpr, OutAlt, OutArg, OutType, OutBinder,
+ FloatsWith, FloatsWithExpr,
+
+ -- The monad
+ SimplM,
initSmpl, returnSmpl, thenSmpl, thenSmpl_,
- mapSmpl, mapAndUnzipSmpl,
+ mapSmpl, mapAndUnzipSmpl, mapAccumLSmpl,
+ getDOptsSmpl,
+
+ -- The simplifier mode
+ setMode, getMode,
+
+ -- Unique supply
+ getUniqueSmpl, getUniquesSmpl, getUniqSupplySmpl,
-- Counting
- SimplCount{-abstract-}, TickType(..), tick, tickN,
- simplCount, detailedSimplCount,
- zeroSimplCount, showSimplCount, combineSimplCounts,
+ SimplCount, Tick(..),
+ tick, freeTick,
+ getSimplCount, zeroSimplCount, pprSimplCount,
+ plusSimplCount, isZeroSimplCount,
- -- Cloning
- cloneId, cloneIds, cloneTyVarSmpl, newIds, newId
+ -- Switch checker
+ SwitchChecker, SwitchResult(..), getSwitchChecker, getSimplIntSwitch,
+ isAmongSimpl, intSwitchSet, switchIsOn,
- -- and to make the interface self-sufficient...
- ) where
+ -- Cost centres
+ getEnclosingCC, setEnclosingCC,
+
+ -- Environments
+ SimplEnv, emptySimplEnv, getSubst, setSubst,
+ getSubstEnv, extendSubst, extendSubstList,
+ getInScope, setInScope, modifyInScope, addNewInScopeIds,
+ setSubstEnv, zapSubstEnv,
-import Ubiq{-uitous-}
+ -- Floats
+ Floats, emptyFloats, isEmptyFloats, unitFloat, addFloats, flattenFloats,
+ allLifted, wrapFloats, floatBinds,
+ addAuxiliaryBind,
-import SmplLoop -- well, cheating sort of
+ -- Inlining,
+ preInlineUnconditionally, postInlineUnconditionally, activeInline, activeRule,
+ inlineMode
+ ) where
+
+#include "HsVersions.h"
-import Id ( mkSysLocal )
-import SimplEnv
-import SrcLoc ( mkUnknownSrcLoc )
-import UniqSupply ( getUnique, getUniques, splitUniqSupply,
+import Id ( Id, idType, idOccInfo, idInlinePragma )
+import CoreSyn
+import CoreUtils ( needsCaseBinding, exprIsTrivial )
+import PprCore () -- Instances
+import CostCentre ( CostCentreStack, subsumedCCS )
+import Var
+import VarEnv
+import VarSet
+import OrdList
+import qualified Subst
+import Subst ( Subst, mkSubst, substEnv,
+ InScopeSet, mkInScopeSet, substInScope,
+ isInScope
+ )
+import Type ( Type, isUnLiftedType )
+import UniqSupply ( uniqsFromSupply, uniqFromSupply, splitUniqSupply,
UniqSupply
)
-import Util ( zipWithEqual, panic )
+import FiniteMap
+import BasicTypes ( TopLevelFlag, isTopLevel,
+ Activation, isActive, isAlwaysActive,
+ OccInfo(..), isOneOcc
+ )
+import CmdLineOpts ( SimplifierSwitch(..), SimplifierMode(..),
+ DynFlags, DynFlag(..), dopt,
+ opt_PprStyle_Debug, opt_HistorySize, opt_SimplNoPreInlining,
+ )
+import Unique ( Unique )
+import Maybes ( expectJust )
+import Outputable
+import Array ( array, (//) )
+import FastTypes
+import GlaExts ( indexArray# )
+
+#if __GLASGOW_HASKELL__ < 503
+import PrelArr ( Array(..) )
+#else
+import GHC.Arr ( Array(..) )
+#endif
+
+infixr 0 `thenSmpl`, `thenSmpl_`
+\end{code}
+
+%************************************************************************
+%* *
+\subsection[Simplify-types]{Type declarations}
+%* *
+%************************************************************************
+
+\begin{code}
+type InBinder = CoreBndr
+type InId = Id -- Not yet cloned
+type InType = Type -- Ditto
+type InBind = CoreBind
+type InExpr = CoreExpr
+type InAlt = CoreAlt
+type InArg = CoreArg
+
+type OutBinder = CoreBndr
+type OutId = Id -- Cloned
+type OutTyVar = TyVar -- Cloned
+type OutType = Type -- Cloned
+type OutBind = CoreBind
+type OutExpr = CoreExpr
+type OutAlt = CoreAlt
+type OutArg = CoreArg
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Floats}
+%* *
+%************************************************************************
+
+\begin{code}
+type FloatsWithExpr = FloatsWith OutExpr
+type FloatsWith a = (Floats, a)
+ -- We return something equivalent to (let b in e), but
+ -- in pieces to avoid the quadratic blowup when floating
+ -- incrementally. Comments just before simplExprB in Simplify.lhs
+
+data Floats = Floats (OrdList OutBind)
+ InScopeSet -- Environment "inside" all the floats
+ Bool -- True <=> All bindings are lifted
+
+allLifted :: Floats -> Bool
+allLifted (Floats _ _ is_lifted) = is_lifted
+
+wrapFloats :: Floats -> OutExpr -> OutExpr
+wrapFloats (Floats bs _ _) body = foldrOL Let body bs
+
+isEmptyFloats :: Floats -> Bool
+isEmptyFloats (Floats bs _ _) = isNilOL bs
+
+floatBinds :: Floats -> [OutBind]
+floatBinds (Floats bs _ _) = fromOL bs
+
+flattenFloats :: Floats -> Floats
+-- Flattens into a single Rec group
+flattenFloats (Floats bs is is_lifted)
+ = ASSERT2( is_lifted, ppr (fromOL bs) )
+ Floats (unitOL (Rec (flattenBinds (fromOL bs)))) is is_lifted
+\end{code}
+
+\begin{code}
+emptyFloats :: SimplEnv -> Floats
+emptyFloats env = Floats nilOL (getInScope env) True
+
+unitFloat :: SimplEnv -> OutId -> OutExpr -> Floats
+-- A single non-rec float; extend the in-scope set
+unitFloat env var rhs = Floats (unitOL (NonRec var rhs))
+ (Subst.extendInScopeSet (getInScope env) var)
+ (not (isUnLiftedType (idType var)))
+
+addFloats :: SimplEnv -> Floats
+ -> (SimplEnv -> SimplM (FloatsWith a))
+ -> SimplM (FloatsWith a)
+addFloats env (Floats b1 is1 l1) thing_inside
+ | isNilOL b1
+ = thing_inside env
+ | otherwise
+ = thing_inside (setInScopeSet env is1) `thenSmpl` \ (Floats b2 is2 l2, res) ->
+ returnSmpl (Floats (b1 `appOL` b2) is2 (l1 && l2), res)
+
+addLetBind :: OutBind -> Floats -> Floats
+addLetBind bind (Floats binds in_scope lifted)
+ = Floats (bind `consOL` binds) in_scope (lifted && is_lifted_bind bind)
-infixr 9 `thenSmpl`, `thenSmpl_`
+is_lifted_bind (Rec _) = True
+is_lifted_bind (NonRec b r) = not (isUnLiftedType (idType b))
-cloneTyVar = panic "cloneTyVar (SimplMonad)"
-mkIdWithNewUniq = panic "mkIdWithNewUniq (SimplMonad)"
+-- addAuxiliaryBind * takes already-simplified things (bndr and rhs)
+-- * extends the in-scope env
+-- * assumes it's a let-bindable thing
+addAuxiliaryBind :: SimplEnv -> OutBind
+ -> (SimplEnv -> SimplM (FloatsWith a))
+ -> SimplM (FloatsWith a)
+ -- Extends the in-scope environment as well as wrapping the bindings
+addAuxiliaryBind env bind thing_inside
+ = ASSERT( case bind of { NonRec b r -> not (needsCaseBinding (idType b) r) ; Rec _ -> True } )
+ thing_inside (addNewInScopeIds env (bindersOf bind)) `thenSmpl` \ (floats, x) ->
+ returnSmpl (addLetBind bind floats, x)
\end{code}
+
%************************************************************************
%* *
\subsection{Monad plumbing}
(Command-line switches move around through the explicitly-passed SimplEnv.)
\begin{code}
-type SmplM result
- = UniqSupply
- -> SimplCount -- things being threaded
- -> (result, SimplCount)
+type SimplM result
+ = DynFlags -- We thread the unique supply because
+ -> UniqSupply -- constantly splitting it is rather expensive
+ -> SimplCount
+ -> (result, UniqSupply, SimplCount)
\end{code}
\begin{code}
-initSmpl :: UniqSupply -- no init count; set to 0
- -> SmplM a
- -> (a, SimplCount)
+initSmpl :: DynFlags
+ -> UniqSupply -- No init count; set to 0
+ -> SimplM a
+ -> (a, SimplCount)
+
+initSmpl dflags us m
+ = case m dflags us (zeroSimplCount dflags) of
+ (result, _, count) -> (result, count)
-initSmpl us m = m us zeroSimplCount
{-# INLINE thenSmpl #-}
{-# INLINE thenSmpl_ #-}
{-# INLINE returnSmpl #-}
-returnSmpl :: a -> SmplM a
-returnSmpl e us sc = (e, sc)
+returnSmpl :: a -> SimplM a
+returnSmpl e dflags us sc = (e, us, sc)
+
+thenSmpl :: SimplM a -> (a -> SimplM b) -> SimplM b
+thenSmpl_ :: SimplM a -> SimplM b -> SimplM b
-thenSmpl :: SmplM a -> (a -> SmplM b) -> SmplM b
-thenSmpl_ :: SmplM a -> SmplM b -> SmplM b
+thenSmpl m k dflags us0 sc0
+ = case (m dflags us0 sc0) of
+ (m_result, us1, sc1) -> k m_result dflags us1 sc1
-thenSmpl m k us sc0
- = case splitUniqSupply us of { (s1, s2) ->
- case (m s1 sc0) of { (m_result, sc1) ->
- k m_result s2 sc1 }}
+thenSmpl_ m k dflags us0 sc0
+ = case (m dflags us0 sc0) of
+ (_, us1, sc1) -> k dflags us1 sc1
+\end{code}
-thenSmpl_ m k us sc0
- = case splitUniqSupply us of { (s1, s2) ->
- case (m s1 sc0) of { (_, sc1) ->
- k s2 sc1 }}
-mapSmpl :: (a -> SmplM b) -> [a] -> SmplM [b]
-mapAndUnzipSmpl :: (a -> SmplM (b, c)) -> [a] -> SmplM ([b],[c])
+\begin{code}
+mapSmpl :: (a -> SimplM b) -> [a] -> SimplM [b]
+mapAndUnzipSmpl :: (a -> SimplM (b, c)) -> [a] -> SimplM ([b],[c])
mapSmpl f [] = returnSmpl []
mapSmpl f (x:xs)
= f x `thenSmpl` \ (r1, r2) ->
mapAndUnzipSmpl f xs `thenSmpl` \ (rs1, rs2) ->
returnSmpl (r1:rs1, r2:rs2)
+
+mapAccumLSmpl f acc [] = returnSmpl (acc, [])
+mapAccumLSmpl f acc (x:xs) = f acc x `thenSmpl` \ (acc', x') ->
+ mapAccumLSmpl f acc' xs `thenSmpl` \ (acc'', xs') ->
+ returnSmpl (acc'', x':xs')
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{The unique supply}
+%* *
+%************************************************************************
+
+\begin{code}
+getUniqSupplySmpl :: SimplM UniqSupply
+getUniqSupplySmpl dflags us sc
+ = case splitUniqSupply us of
+ (us1, us2) -> (us1, us2, sc)
+
+getUniqueSmpl :: SimplM Unique
+getUniqueSmpl dflags us sc
+ = case splitUniqSupply us of
+ (us1, us2) -> (uniqFromSupply us1, us2, sc)
+
+getUniquesSmpl :: SimplM [Unique]
+getUniquesSmpl dflags us sc
+ = case splitUniqSupply us of
+ (us1, us2) -> (uniqsFromSupply us1, us2, sc)
+
+getDOptsSmpl :: SimplM DynFlags
+getDOptsSmpl dflags us sc
+ = (dflags, us, sc)
\end{code}
%* *
%************************************************************************
-The assoc list isn't particularly costly, because we only use
-the number of ticks in ``real life.''
+\begin{code}
+getSimplCount :: SimplM SimplCount
+getSimplCount dflags us sc = (sc, us, sc)
+
+tick :: Tick -> SimplM ()
+tick t dflags us sc
+ = sc' `seq` ((), us, sc')
+ where
+ sc' = doTick t sc
-The right thing to do, if you want that to go fast, is thread
-a mutable array through @SimplM@.
+freeTick :: Tick -> SimplM ()
+-- Record a tick, but don't add to the total tick count, which is
+-- used to decide when nothing further has happened
+freeTick t dflags us sc
+ = sc' `seq` ((), us, sc')
+ where
+ sc' = doFreeTick t sc
+\end{code}
\begin{code}
-data SimplCount
- = SimplCount FAST_INT -- number of ticks
- [(TickType, Int)] -- assoc list of all diff kinds of ticks
-
-data TickType
- = UnfoldingDone | MagicUnfold | ConReused
- | CaseFloatFromLet | CaseOfCase
- | LetFloatFromLet | LetFloatFromCase
- | KnownBranch | Let2Case
- | CaseMerge | CaseElim
- | CaseIdentity
- | AtomicRhs -- Rhs of a let-expression was an atom
- | EtaExpansion
- | CaseOfError
- | TyBetaReduction
- | BetaReduction
- {- BEGIN F/B ENTRIES -}
- -- the 8 rules
- | FoldrBuild -- foldr f z (build g) ==>
- | FoldrAugment -- foldr f z (augment g z) ==>
- | Foldr_Nil -- foldr f z [] ==>
- | Foldr_List -- foldr f z (x:...) ==>
-
- | FoldlBuild -- foldl f z (build g) ==>
- | FoldlAugment -- foldl f z (augment g z) ==>
- | Foldl_Nil -- foldl f z [] ==>
- | Foldl_List -- foldl f z (x:...) ==>
-
- | Foldr_Cons_Nil -- foldr (:) [] => id
- | Foldr_Cons -- foldr (:) => flip (++)
-
- | Str_FoldrStr -- foldr f z "hello" => unpackFoldrPS# f z "hello"
- | Str_UnpackCons -- unpackFoldrPS# (:) z "hello" => unpackAppendPS# z "hello"
- | Str_UnpackNil -- unpackAppendPS# [] "hello" => "hello"
- {- END F/B ENTRIES -}
- deriving (Eq, Ord, Ix)
-
-instance Text TickType where
- showsPrec p UnfoldingDone = showString "UnfoldingDone "
- showsPrec p MagicUnfold = showString "MagicUnfold "
- showsPrec p ConReused = showString "ConReused "
- showsPrec p CaseFloatFromLet= showString "CaseFloatFromLet "
- showsPrec p CaseOfCase = showString "CaseOfCase "
- showsPrec p LetFloatFromLet = showString "LetFloatFromLet "
- showsPrec p LetFloatFromCase= showString "LetFloatFromCase "
- showsPrec p KnownBranch = showString "KnownBranch "
- showsPrec p Let2Case = showString "Let2Case "
- showsPrec p CaseMerge = showString "CaseMerge "
- showsPrec p CaseElim = showString "CaseElim "
- showsPrec p CaseIdentity = showString "CaseIdentity "
- showsPrec p AtomicRhs = showString "AtomicRhs "
- showsPrec p EtaExpansion = showString "EtaExpansion "
- showsPrec p CaseOfError = showString "CaseOfError "
- showsPrec p TyBetaReduction = showString "TyBetaReduction "
- showsPrec p BetaReduction = showString "BetaReduction "
- -- Foldr/Build Stuff:
- showsPrec p FoldrBuild = showString "FoldrBuild "
- showsPrec p FoldrAugment = showString "FoldrAugment "
- showsPrec p Foldr_Nil = showString "Foldr_Nil "
- showsPrec p Foldr_List = showString "Foldr_List "
-
- showsPrec p FoldlBuild = showString "FoldlBuild "
- showsPrec p FoldlAugment = showString "FoldlAugment "
- showsPrec p Foldl_Nil = showString "Foldl_Nil "
- showsPrec p Foldl_List = showString "Foldl_List "
-
- showsPrec p Foldr_Cons_Nil = showString "Foldr_Cons_Nil "
- showsPrec p Foldr_Cons = showString "Foldr_Cons "
-
- showsPrec p Str_FoldrStr = showString "Str_FoldrStr "
- showsPrec p Str_UnpackCons = showString "Str_UnpackCons "
- showsPrec p Str_UnpackNil = showString "Str_UnpackNil "
-
-showSimplCount :: SimplCount -> String
-
-showSimplCount (SimplCount _ stuff)
- = shw stuff
- where
- shw [] = ""
- shw ((t,n):tns) | n /= 0 = show t ++ ('\t' : show n) ++ ('\n' : shw tns)
- | otherwise = shw tns
-
-zeroSimplCount :: SimplCount
-zeroSimplCount
- = SimplCount ILIT(0)
- [ (UnfoldingDone, 0),
- (MagicUnfold, 0),
- (ConReused, 0),
- (CaseFloatFromLet, 0),
- (CaseOfCase, 0),
- (LetFloatFromLet, 0),
- (LetFloatFromCase, 0),
- (KnownBranch, 0),
- (Let2Case, 0),
- (CaseMerge, 0),
- (CaseElim, 0),
- (CaseIdentity, 0),
- (AtomicRhs, 0),
- (EtaExpansion, 0),
- (CaseOfError, 0),
- (TyBetaReduction,0),
- (BetaReduction,0),
- -- Foldr/Build Stuff:
- (FoldrBuild, 0),
- (FoldrAugment, 0),
- (Foldr_Nil, 0),
- (Foldr_List, 0),
- (FoldlBuild, 0),
- (FoldlAugment, 0),
- (Foldl_Nil, 0),
- (Foldl_List, 0),
- (Foldr_Cons_Nil, 0),
- (Foldr_Cons, 0),
-
- (Str_FoldrStr, 0),
- (Str_UnpackCons, 0),
- (Str_UnpackNil, 0) ]
---
---= array (con2tag_TickType UnfoldingDone, con2tag_TickType FoldrInline)
--- [ i := 0 | i <- indices zeroSimplCount ]
+verboseSimplStats = opt_PprStyle_Debug -- For now, anyway
+
+zeroSimplCount :: DynFlags -> SimplCount
+isZeroSimplCount :: SimplCount -> Bool
+pprSimplCount :: SimplCount -> SDoc
+doTick, doFreeTick :: Tick -> SimplCount -> SimplCount
+plusSimplCount :: SimplCount -> SimplCount -> SimplCount
\end{code}
-Counting-related monad functions:
\begin{code}
-tick :: TickType -> SmplM ()
+data SimplCount = VerySimplZero -- These two are used when
+ | VerySimplNonZero -- we are only interested in
+ -- termination info
-tick tick_type us (SimplCount n stuff)
- = ((), SimplCount (n _ADD_ ILIT(1))
-#ifdef OMIT_SIMPL_COUNTS
- stuff -- don't change anything
-#else
- (inc_tick stuff)
-#endif
- )
+ | SimplCount {
+ ticks :: !Int, -- Total ticks
+ details :: !TickCounts, -- How many of each type
+ n_log :: !Int, -- N
+ log1 :: [Tick], -- Last N events; <= opt_HistorySize
+ log2 :: [Tick] -- Last opt_HistorySize events before that
+ }
+
+type TickCounts = FiniteMap Tick Int
+
+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 = emptyFM,
+ n_log = 0, log1 = [], log2 = []}
+ | otherwise
+ = VerySimplZero
+
+isZeroSimplCount VerySimplZero = True
+isZeroSimplCount (SimplCount { ticks = 0 }) = True
+isZeroSimplCount other = False
+
+doFreeTick tick sc@SimplCount { details = dts }
+ = dts' `seqFM` sc { details = dts' }
where
- inc_tick [] = panic "couldn't inc_tick!"
- inc_tick (x@(ttype, cnt) : xs)
- = if ttype == tick_type then
- let
- incd = cnt + 1
- in
- (ttype, incd) : xs
- else
- x : inc_tick xs
-
-tickN :: TickType -> Int -> SmplM ()
-
-tickN tick_type IBOX(increment) us (SimplCount n stuff)
- = ((), SimplCount (n _ADD_ increment)
-#ifdef OMIT_SIMPL_COUNTS
- stuff -- don't change anything
-#else
- (inc_tick stuff)
-#endif
- )
+ dts' = dts `addTick` tick
+doFreeTick tick sc = sc
+
+-- Gross hack to persuade GHC 3.03 to do this important seq
+seqFM fm x | isEmptyFM fm = x
+ | otherwise = x
+
+doTick tick sc@SimplCount { ticks = tks, details = dts, n_log = nl, log1 = l1, log2 = l2 }
+ | nl >= opt_HistorySize = sc1 { n_log = 1, log1 = [tick], log2 = l1 }
+ | otherwise = sc1 { n_log = nl+1, log1 = tick : l1 }
where
- inc_tick [] = panic "couldn't inc_tick!"
- inc_tick (x@(ttype, cnt) : xs)
- = if ttype == tick_type then
- let
- incd = cnt + IBOX(increment)
- in
- (ttype, incd) : xs
- else
- x : inc_tick xs
-
-simplCount :: SmplM Int
-simplCount us sc@(SimplCount n _) = (IBOX(n), sc)
-
-detailedSimplCount :: SmplM SimplCount
-detailedSimplCount us sc = (sc, sc)
-
-combineSimplCounts :: SimplCount -> SimplCount -> SimplCount
-
-#ifdef OMIT_SIMPL_COUNTS
-combineSimplCounts (SimplCount n1 stuff1) (SimplCount n2 stuff2)
- = SimplCount (n1 _ADD_ n2)
- stuff1 -- just pick one
-#else
-combineSimplCounts (SimplCount n1 stuff1) (SimplCount n2 stuff2)
- = SimplCount (n1 _ADD_ n2)
- (zipWithEqual (\ (t1,c1) (t2,c2) -> (t1,c1+c2)) stuff1 stuff2)
-#endif
+ sc1 = sc { ticks = tks+1, details = dts `addTick` tick }
+
+doTick tick sc = VerySimplNonZero -- The very simple case
+
+
+-- Don't use plusFM_C because that's lazy, and we want to
+-- be pretty strict here!
+addTick :: TickCounts -> Tick -> TickCounts
+addTick fm tick = case lookupFM fm tick of
+ Nothing -> addToFM fm tick 1
+ Just n -> n1 `seq` addToFM fm tick n1
+ where
+ n1 = n+1
+
+
+plusSimplCount sc1@(SimplCount { ticks = tks1, details = dts1 })
+ sc2@(SimplCount { ticks = tks2, details = dts2 })
+ = log_base { ticks = tks1 + tks2, details = plusFM_C (+) 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 VerySimplZero VerySimplZero = VerySimplZero
+plusSimplCount sc1 sc2 = VerySimplNonZero
+
+pprSimplCount VerySimplZero = ptext SLIT("Total ticks: ZERO!")
+pprSimplCount VerySimplNonZero = ptext SLIT("Total ticks: NON-ZERO!")
+pprSimplCount (SimplCount { ticks = tks, details = dts, log1 = l1, log2 = l2 })
+ = vcat [ptext SLIT("Total ticks: ") <+> int tks,
+ text "",
+ pprTickCounts (fmToList dts),
+ if verboseSimplStats then
+ vcat [text "",
+ 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 ticks@((tick,_):_)
+ | verboseSimplStats || isRuleFired tick
+ = nest 4 (vcat [int n <+> pprTickCts tick | (tick,n) <- ticks])
+ | otherwise
+ = empty
\end{code}
%************************************************************************
%* *
-\subsection{Monad primitives}
+\subsection{Ticks}
%* *
%************************************************************************
\begin{code}
-newId :: Type -> SmplM Id
-newId ty us sc
- = (mkSysLocal SLIT("s") uniq ty mkUnknownSrcLoc, sc)
+data Tick
+ = PreInlineUnconditionally Id
+ | PostInlineUnconditionally Id
+
+ | UnfoldingDone Id
+ | RuleFired FAST_STRING -- 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
+
+isRuleFired (RuleFired _) = True
+isRuleFired other = False
+
+instance Outputable Tick where
+ ppr tick = text (tickString tick) <+> pprTickCts tick
+
+instance Eq Tick where
+ a == b = case a `cmpTick` b of { EQ -> True; other -> 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 other = empty
+
+cmpTick :: Tick -> Tick -> Ordering
+cmpTick a b = case (tickToTag a `compare` tickToTag b) of
+ GT -> GT
+ EQ | isRuleFired a || verboseSimplStats -> cmpEqTick a b
+ | otherwise -> EQ
+ LT -> LT
+ -- Always distinguish RuleFired, so that the stats
+ -- can report them even in non-verbose mode
+
+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 other1 other2 = EQ
+\end{code}
+
+
+
+%************************************************************************
+%* *
+\subsubsection{The @SimplEnv@ type}
+%* *
+%************************************************************************
+
+
+\begin{code}
+data SimplEnv
+ = SimplEnv {
+ seMode :: SimplifierMode,
+ seChkr :: SwitchChecker,
+ seCC :: CostCentreStack, -- The enclosing CCS (when profiling)
+ seSubst :: Subst -- The current substitution
+ }
+ -- The range of the substitution is OutType and OutExpr resp
+ --
+ -- The substitution is idempotent
+ -- It *must* be applied; things in its domain simply aren't
+ -- bound in the result.
+ --
+ -- The substitution usually maps an Id to its clone,
+ -- but if the orig defn is a let-binding, and
+ -- the RHS of the let simplifies to an atom,
+ -- we just add the binding to the substitution and elide the let.
+
+ -- The in-scope part of Subst includes *all* in-scope TyVars and Ids
+ -- The elements of the set may have better IdInfo than the
+ -- occurrences of in-scope Ids, and (more important) they will
+ -- have a correctly-substituted type. So we use a lookup in this
+ -- set to replace occurrences
+
+emptySimplEnv :: SimplifierMode -> [SimplifierSwitch] -> VarSet -> SimplEnv
+emptySimplEnv mode switches in_scope
+ = SimplEnv { seChkr = isAmongSimpl switches, seCC = subsumedCCS, seMode = mode,
+ seSubst = mkSubst (mkInScopeSet in_scope) emptySubstEnv }
+ -- The top level "enclosing CC" is "SUBSUMED".
+
+---------------------
+getSwitchChecker :: SimplEnv -> SwitchChecker
+getSwitchChecker env = seChkr env
+
+---------------------
+getMode :: SimplEnv -> SimplifierMode
+getMode env = seMode env
+
+setMode :: SimplifierMode -> SimplEnv -> SimplEnv
+setMode mode env = env { seMode = mode }
+
+---------------------
+getEnclosingCC :: SimplEnv -> CostCentreStack
+getEnclosingCC env = seCC env
+
+setEnclosingCC :: SimplEnv -> CostCentreStack -> SimplEnv
+setEnclosingCC env cc = env {seCC = cc}
+
+---------------------
+getSubst :: SimplEnv -> Subst
+getSubst env = seSubst env
+
+setSubst :: SimplEnv -> Subst -> SimplEnv
+setSubst env subst = env {seSubst = subst}
+
+extendSubst :: SimplEnv -> CoreBndr -> SubstResult -> SimplEnv
+extendSubst env@(SimplEnv {seSubst = subst}) var res
+ = env {seSubst = Subst.extendSubst subst var res}
+
+extendSubstList :: SimplEnv -> [CoreBndr] -> [SubstResult] -> SimplEnv
+extendSubstList env@(SimplEnv {seSubst = subst}) vars ress
+ = env {seSubst = Subst.extendSubstList subst vars ress}
+
+---------------------
+getInScope :: SimplEnv -> InScopeSet
+getInScope env = substInScope (seSubst env)
+
+setInScope :: SimplEnv -> SimplEnv -> SimplEnv
+setInScope env env_with_in_scope = setInScopeSet env (getInScope env_with_in_scope)
+
+setInScopeSet :: SimplEnv -> InScopeSet -> SimplEnv
+setInScopeSet env@(SimplEnv {seSubst = subst}) in_scope
+ = env {seSubst = Subst.setInScope subst in_scope}
+
+addNewInScopeIds :: SimplEnv -> [CoreBndr] -> SimplEnv
+ -- The new Ids are guaranteed to be freshly allocated
+addNewInScopeIds env@(SimplEnv {seSubst = subst}) vs
+ = env {seSubst = Subst.extendNewInScopeList subst vs}
+
+modifyInScope :: SimplEnv -> CoreBndr -> CoreBndr -> SimplEnv
+modifyInScope env@(SimplEnv {seSubst = subst}) v v'
+ = env {seSubst = Subst.modifyInScope subst v v'}
+
+---------------------
+getSubstEnv :: SimplEnv -> SubstEnv
+getSubstEnv env = substEnv (seSubst env)
+
+setSubstEnv :: SimplEnv -> SubstEnv -> SimplEnv
+setSubstEnv env@(SimplEnv {seSubst = subst}) senv
+ = env {seSubst = Subst.setSubstEnv subst senv}
+
+zapSubstEnv :: SimplEnv -> SimplEnv
+zapSubstEnv env@(SimplEnv {seSubst = subst})
+ = env {seSubst = Subst.zapSubstEnv subst}
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Decisions about inlining}
+%* *
+%************************************************************************
+
+Inlining is controlled partly by the SimplifierMode switch. This has two
+settings:
+
+ SimplGently (a) Simplifying before specialiser/full laziness
+ (b) Simplifiying inside INLINE pragma
+ (c) Simplifying the LHS of a rule
+
+ SimplPhase n Used at all other times
+
+The key thing about SimplGently is that it does no call-site inlining.
+Before full laziness we must be careful not to inline wrappers,
+because doing so inhibits floating
+ e.g. ...(case f x of ...)...
+ ==> ...(case (case x of I# x# -> fw x#) of ...)...
+ ==> ...(case x of I# x# -> case fw x# of ...)...
+and now the redex (f x) isn't floatable any more.
+
+INLINE pragmas
+~~~~~~~~~~~~~~
+SimplGently is also used as the mode to simplify inside an InlineMe note.
+
+\begin{code}
+inlineMode :: SimplifierMode
+inlineMode = SimplGently
+\end{code}
+
+It really is important to switch off inlinings inside such
+expressions. Consider the following example
+
+ let f = \pq -> BIG
+ in
+ let g = \y -> f y y
+ {-# INLINE g #-}
+ in ...g...g...g...g...g...
+
+Now, if that's the ONLY occurrence of f, it will be inlined inside g,
+and thence copied multiple times when g is inlined.
+
+
+This function may be inlinined in other modules, so we
+don't want to remove (by inlining) calls to functions that have
+specialisations, or that may have transformation rules in an importing
+scope.
+
+E.g. {-# INLINE f #-}
+ f x = ...g...
+
+and suppose that g is strict *and* has specialisations. If we inline
+g's wrapper, we deny f the chance of getting the specialised version
+of g when f is inlined at some call site (perhaps in some other
+module).
+
+It's also important not to inline a worker back into a wrapper.
+A wrapper looks like
+ wraper = inline_me (\x -> ...worker... )
+Normally, the inline_me prevents the worker getting inlined into
+the wrapper (initially, the worker's only call site!). But,
+if the wrapper is sure to be called, the strictness analyser will
+mark it 'demanded', so when the RHS is simplified, it'll get an ArgOf
+continuation. That's why the keep_inline predicate returns True for
+ArgOf continuations. It shouldn't do any harm not to dissolve the
+inline-me note under these circumstances.
+
+Note that the result is that we do very little simplification
+inside an InlineMe.
+
+ all xs = foldr (&&) True xs
+ any p = all . map p {-# INLINE any #-}
+
+Problem: any won't get deforested, and so if it's exported and the
+importer doesn't use the inlining, (eg passes it as an arg) then we
+won't get deforestation at all. We havn't solved this problem yet!
+
+
+preInlineUnconditionally
+~~~~~~~~~~~~~~~~~~~~~~~~
+@preInlineUnconditionally@ examines a bndr to see if it is used just
+once in a completely safe way, so that it is safe to discard the
+binding inline its RHS at the (unique) usage site, REGARDLESS of how
+big the RHS might be. If this is the case we don't simplify the RHS
+first, but just inline it un-simplified.
+
+This is much better than first simplifying a perhaps-huge RHS and then
+inlining and re-simplifying it. Indeed, it can be at least quadratically
+better. Consider
+
+ x1 = e1
+ x2 = e2[x1]
+ x3 = e3[x2]
+ ...etc...
+ xN = eN[xN-1]
+
+We may end up simplifying e1 N times, e2 N-1 times, e3 N-3 times etc.
+
+NB: we don't even look at the RHS to see if it's trivial
+We might have
+ x = y
+where x is used many times, but this is the unique occurrence of y.
+We should NOT inline x at all its uses, because then we'd do the same
+for y -- aargh! So we must base this pre-rhs-simplification decision
+solely on x's occurrences, not on its rhs.
+
+Evne RHSs labelled InlineMe aren't caught here, because there might be
+no benefit from inlining at the call site.
+
+[Sept 01] Don't unconditionally inline a top-level thing, because that
+can simply make a static thing into something built dynamically. E.g.
+ x = (a,b)
+ main = \s -> h x
+
+[Remember that we treat \s as a one-shot lambda.] No point in
+inlining x unless there is something interesting about the call site.
+
+But watch out: if you aren't careful, some useful foldr/build fusion
+can be lost (most notably in spectral/hartel/parstof) because the
+foldr didn't see the build. Doing the dynamic allocation isn't a big
+deal, in fact, but losing the fusion can be. But the right thing here
+seems to be to do a callSiteInline based on the fact that there is
+something interesting about the call site (it's strict). Hmm. That
+seems a bit fragile.
+
+Conclusion: inline top level things gaily until Phase 0 (the last
+phase), at which point don't.
+
+\begin{code}
+preInlineUnconditionally :: SimplEnv -> TopLevelFlag -> InId -> Bool
+preInlineUnconditionally env top_lvl bndr
+ | isTopLevel top_lvl, SimplPhase 0 <- phase = False
+-- If we don't have this test, consider
+-- x = length [1,2,3]
+-- The full laziness pass carefully floats all the cons cells to
+-- top level, and preInlineUnconditionally floats them all back in.
+-- Result is (a) static allocation replaced by dynamic allocation
+-- (b) many simplifier iterations because this tickles
+-- a related problem; only one inlining per pass
+--
+-- On the other hand, I have seen cases where top-level fusion is
+-- lost if we don't inline top level thing (e.g. string constants)
+-- Hence the test for phase zero (which is the phase for all the final
+-- simplifications). Until phase zero we take no special notice of
+-- top level things, but then we become more leery about inlining
+-- them.
+
+ | not active = False
+ | opt_SimplNoPreInlining = False
+ | otherwise = case idOccInfo bndr of
+ IAmDead -> True -- Happens in ((\x.1) v)
+ OneOcc in_lam once -> not in_lam && once
+ -- Not inside a lambda, one occurrence ==> safe!
+ other -> False
where
- uniq = getUnique us
+ phase = getMode env
+ active = case phase of
+ SimplGently -> isAlwaysActive prag
+ SimplPhase n -> isActive n prag
+ prag = idInlinePragma bndr
+\end{code}
+
+postInlineUnconditionally
+~~~~~~~~~~~~~~~~~~~~~~~~~
+@postInlineUnconditionally@ decides whether to unconditionally inline
+a thing based on the form of its RHS; in particular if it has a
+trivial RHS. If so, we can inline and discard the binding altogether.
+
+NB: a loop breaker has must_keep_binding = True and non-loop-breakers
+only have *forward* references Hence, it's safe to discard the binding
+
+NOTE: This isn't our last opportunity to inline. We're at the binding
+site right now, and we'll get another opportunity when we get to the
+ocurrence(s)
+
+Note that we do this unconditional inlining only for trival RHSs.
+Don't inline even WHNFs inside lambdas; doing so may simply increase
+allocation when the function is called. This isn't the last chance; see
+NOTE above.
+
+NB: Even inline pragmas (e.g. IMustBeINLINEd) are ignored here Why?
+Because we don't even want to inline them into the RHS of constructor
+arguments. See NOTE above
+
+NB: At one time even NOINLINE was ignored here: if the rhs is trivial
+it's best to inline it anyway. We often get a=E; b=a from desugaring,
+with both a and b marked NOINLINE. But that seems incompatible with
+our new view that inlining is like a RULE, so I'm sticking to the 'active'
+story for now.
-newIds :: [Type] -> SmplM [Id]
-newIds tys us sc
- = (zipWithEqual mk_id tys uniqs, sc)
+\begin{code}
+postInlineUnconditionally :: SimplEnv -> OutId -> OccInfo -> OutExpr -> Bool
+postInlineUnconditionally env bndr occ_info rhs
+ = exprIsTrivial rhs && active && isOneOcc occ_info
+ -- We used to have (not loop_breaker && not (isExportedId bndr))
+ -- instead of (isOneOcc occ_info). Indeed, you might suppose that
+ -- there is nothing wrong with substituting for a trivial RHS, even
+ -- if it occurs many times. But consider
+ -- x = y
+ -- h = _inline_me_ (...x...)
+ -- Here we do *not* want to have x inlined, even though the RHS is
+ -- trivial, becuase the contract for an INLINE pragma is "no inlining".
+ -- This is important in the rules for the Prelude (e.g. PrelEnum.eftInt).
where
- uniqs = getUniques (length tys) us
- mk_id ty uniq = mkSysLocal SLIT("s") uniq ty mkUnknownSrcLoc
+ active = case getMode env of
+ SimplGently -> isAlwaysActive prag
+ SimplPhase n -> isActive n prag
+ prag = idInlinePragma bndr
+\end{code}
-cloneTyVarSmpl :: TyVar -> SmplM TyVar
+blackListInline tells if we must not inline at a call site because the
+Id's inline pragma says not to do so.
-cloneTyVarSmpl tyvar us sc
- = (new_tyvar, sc)
+However, blackListInline is ignored for things with with Compulsory inlinings,
+because they don't have bindings, so we must inline them no matter how
+gentle we are being.
+
+\begin{code}
+activeInline :: SimplEnv -> OutId -> OccInfo -> Bool
+activeInline env id occ
+ = case getMode env of
+ SimplGently -> isAlwaysActive prag && isOneOcc occ
+ -- No inlining at all when doing gentle stuff,
+ -- except for things that occur once
+ -- The reason is that too little clean-up happens if you
+ -- don't inline use-once things. Also a bit of inlining is *good* for
+ -- full laziness; it can expose constant sub-expressions.
+ -- Example in spectral/mandel/Mandel.hs, where the mandelset
+ -- function gets a useful let-float if you inline windowToViewport
+
+ -- NB: we used to have a second exception, for data con wrappers.
+ -- On the grounds that we use gentle mode for rule LHSs, and
+ -- they match better when data con wrappers are inlined.
+ -- But that only really applies to the trivial wrappers (like (:)),
+ -- and they are now constructed as Compulsory unfoldings (in MkId)
+ -- so they'll happen anyway.
+
+ SimplPhase n -> isActive n prag
where
- uniq = getUnique us
- new_tyvar = cloneTyVar tyvar uniq
+ prag = idInlinePragma id
+
+activeRule :: SimplEnv -> Maybe (Activation -> Bool)
+-- Nothing => No rules at all
+activeRule env
+ = case getMode env of
+ SimplGently -> Nothing -- No rules in gentle mode
+ SimplPhase n -> Just (isActive n)
+\end{code}
-cloneId :: SimplEnv -> InBinder -> SmplM OutId
-cloneId env (id,_) us sc
- = (mkIdWithNewUniq id_with_new_ty uniq, sc)
+
+%************************************************************************
+%* *
+\subsubsection{Command-line switches}
+%* *
+%************************************************************************
+
+\begin{code}
+getSimplIntSwitch :: SwitchChecker -> (Int-> SimplifierSwitch) -> Int
+getSimplIntSwitch chkr switch
+ = expectJust "getSimplIntSwitch" (intSwitchSet chkr switch)
+
+switchIsOn :: (switch -> SwitchResult) -> switch -> Bool
+
+switchIsOn lookup_fn switch
+ = case (lookup_fn switch) of
+ SwBool False -> False
+ _ -> True
+
+intSwitchSet :: (switch -> SwitchResult)
+ -> (Int -> switch)
+ -> Maybe Int
+
+intSwitchSet lookup_fn switch
+ = case (lookup_fn (switch (panic "intSwitchSet"))) of
+ SwInt int -> Just int
+ _ -> Nothing
+\end{code}
+
+
+\begin{code}
+type SwitchChecker = SimplifierSwitch -> SwitchResult
+
+data SwitchResult
+ = SwBool Bool -- on/off
+ | SwString FAST_STRING -- nothing or a String
+ | SwInt Int -- nothing or an Int
+
+isAmongSimpl :: [SimplifierSwitch] -> SimplifierSwitch -> SwitchResult
+isAmongSimpl on_switches -- Switches mentioned later occur *earlier*
+ -- in the list; defaults right at the end.
+ = let
+ tidied_on_switches = foldl rm_dups [] on_switches
+ -- The fold*l* ensures that we keep the latest switches;
+ -- ie the ones that occur earliest in the list.
+
+ sw_tbl :: Array Int SwitchResult
+ sw_tbl = (array (0, lAST_SIMPL_SWITCH_TAG) -- bounds...
+ all_undefined)
+ // defined_elems
+
+ all_undefined = [ (i, SwBool False) | i <- [0 .. lAST_SIMPL_SWITCH_TAG ] ]
+
+ defined_elems = map mk_assoc_elem tidied_on_switches
+ in
+ -- (avoid some unboxing, bounds checking, and other horrible things:)
+#if __GLASGOW_HASKELL__ < 405
+ case sw_tbl of { Array bounds_who_needs_'em stuff ->
+#else
+ case sw_tbl of { Array _ _ stuff ->
+#endif
+ \ switch ->
+ case (indexArray# stuff (tagOf_SimplSwitch switch)) of
+#if __GLASGOW_HASKELL__ < 400
+ Lift v -> v
+#elif __GLASGOW_HASKELL__ < 403
+ (# _, v #) -> v
+#else
+ (# v #) -> v
+#endif
+ }
where
- id_with_new_ty = simplTyInId env id
- uniq = getUnique us
+ mk_assoc_elem k@(MaxSimplifierIterations lvl)
+ = (iBox (tagOf_SimplSwitch k), SwInt lvl)
+ mk_assoc_elem k
+ = (iBox (tagOf_SimplSwitch k), SwBool True) -- I'm here, Mom!
-cloneIds :: SimplEnv -> [InBinder] -> SmplM [OutId]
-cloneIds env binders = mapSmpl (cloneId env) binders
+ -- cannot have duplicates if we are going to use the array thing
+ rm_dups switches_so_far switch
+ = if switch `is_elem` switches_so_far
+ then switches_so_far
+ else switch : switches_so_far
+ where
+ sw `is_elem` [] = False
+ sw `is_elem` (s:ss) = (tagOf_SimplSwitch sw) ==# (tagOf_SimplSwitch s)
+ || sw `is_elem` ss
\end{code}
+
+These things behave just like enumeration types.
+
+\begin{code}
+instance Eq SimplifierSwitch where
+ a == b = tagOf_SimplSwitch a ==# tagOf_SimplSwitch b
+
+instance Ord SimplifierSwitch where
+ a < b = tagOf_SimplSwitch a <# tagOf_SimplSwitch b
+ a <= b = tagOf_SimplSwitch a <=# tagOf_SimplSwitch b
+
+
+tagOf_SimplSwitch (MaxSimplifierIterations _) = _ILIT(1)
+tagOf_SimplSwitch NoCaseOfCase = _ILIT(2)
+
+-- If you add anything here, be sure to change lAST_SIMPL_SWITCH_TAG, too!
+
+lAST_SIMPL_SWITCH_TAG = 2
+\end{code}
+
projects / ghc-hetmet.git / blobdiff