X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=7e17ed1266d573b3954a24f235b7a828ce3db439;hb=f016a43fcbcca53a284e8d6206705ed468a97736;hp=2a305073f7e06fa80e27ef86dcba97def6105e60;hpb=29ad936c0443b6af87c26e19d61d1352ac5e7f3e;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index 2a30507..7e17ed1 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -1,600 +1,561 @@ -% -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 -% -\section[SimplCore]{Driver for simplifying @Core@ programs} - -\begin{code} -module SimplCore ( core2core ) where - -#include "HsVersions.h" - -import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), - SwitchResult(..), switchIsOn, intSwitchSet, - opt_D_dump_occur_anal, opt_D_dump_rules, - opt_D_dump_simpl_iterations, - opt_D_dump_simpl_stats, - opt_D_dump_simpl, opt_D_dump_rules, - opt_D_verbose_core2core, - opt_D_dump_occur_anal, - opt_UsageSPOn, - ) -import CoreLint ( beginPass, endPass ) -import CoreTidy ( tidyCorePgm ) -import CoreSyn -import Rules ( RuleBase, ProtoCoreRule(..), pprProtoCoreRule, prepareRuleBase, orphanRule ) -import CoreUnfold -import PprCore ( pprCoreBindings ) -import OccurAnal ( occurAnalyseBinds ) -import CoreUtils ( exprIsTrivial, coreExprType ) -import Simplify ( simplTopBinds, simplExpr ) -import SimplUtils ( etaCoreExpr, findDefault, simplBinders ) -import SimplMonad -import Const ( Con(..), Literal(..), literalType, mkMachInt ) -import ErrUtils ( dumpIfSet ) -import FloatIn ( floatInwards ) -import FloatOut ( floatOutwards ) -import Id ( Id, mkSysLocal, mkVanillaId, isBottomingId, - idType, setIdType, idName, idInfo, setIdNoDiscard - ) -import IdInfo ( InlinePragInfo(..), specInfo, setSpecInfo, - inlinePragInfo, setInlinePragInfo, - setUnfoldingInfo, setDemandInfo - ) -import Demand ( wwLazy ) -import VarEnv -import VarSet -import Module ( Module ) -import Name ( mkLocalName, tidyOccName, tidyTopName, - NamedThing(..), OccName - ) -import TyCon ( TyCon, isDataTyCon ) -import PrimOp ( PrimOp(..) ) -import PrelInfo ( unpackCStringId, unpackCString2Id, addr2IntegerId ) -import Type ( Type, splitAlgTyConApp_maybe, - isUnLiftedType, - tidyType, tidyTypes, tidyTopType, tidyTyVar, tidyTyVars, - Type - ) -import TysWiredIn ( smallIntegerDataCon, isIntegerTy ) -import LiberateCase ( liberateCase ) -import SAT ( doStaticArgs ) -import Specialise ( specProgram) -import UsageSPInf ( doUsageSPInf ) -import StrictAnal ( saBinds ) -import WorkWrap ( wwTopBinds ) -import CprAnalyse ( cprAnalyse ) - -import Unique ( Unique, Uniquable(..), - ratioTyConKey - ) -import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply, uniqFromSupply ) -import Constants ( tARGET_MIN_INT, tARGET_MAX_INT ) -import Util ( mapAccumL ) -import SrcLoc ( noSrcLoc ) -import Bag -import Maybes -import IO ( hPutStr, stderr ) -import Outputable - -import Ratio ( numerator, denominator ) -\end{code} - -%************************************************************************ -%* * -\subsection{The driver for the simplifier} -%* * -%************************************************************************ - -\begin{code} -core2core :: [CoreToDo] -- Spec of what core-to-core passes to do - -> [CoreBind] -- Binds in - -> [ProtoCoreRule] -- Rules - -> IO ([CoreBind], [ProtoCoreRule]) - -core2core core_todos binds rules - = do - us <- mkSplitUniqSupply 's' - let (cp_us, us1) = splitUniqSupply us - (ru_us, ps_us) = splitUniqSupply us1 - - better_rules <- simplRules ru_us rules binds - - let (binds1, rule_base) = prepareRuleBase binds better_rules - - -- Do the main business - (stats, processed_binds) <- doCorePasses zeroSimplCount cp_us binds1 - rule_base core_todos - - dumpIfSet opt_D_dump_simpl_stats - "Grand total simplifier statistics" - (pprSimplCount stats) - - -- Do the post-simplification business - post_simpl_binds <- doPostSimplification ps_us processed_binds - - -- Return results - return (post_simpl_binds, filter orphanRule better_rules) - - -doCorePasses stats us binds irs [] - = return (stats, binds) - -doCorePasses stats us binds irs (to_do : to_dos) - = do - let (us1, us2) = splitUniqSupply us - (stats1, binds1) <- doCorePass us1 binds irs to_do - doCorePasses (stats `plusSimplCount` stats1) us2 binds1 irs to_dos - -doCorePass us binds rb (CoreDoSimplify sw_chkr) = _scc_ "Simplify" simplifyPgm rb sw_chkr us binds -doCorePass us binds rb CoreLiberateCase = _scc_ "LiberateCase" noStats (liberateCase binds) -doCorePass us binds rb CoreDoFloatInwards = _scc_ "FloatInwards" noStats (floatInwards binds) -doCorePass us binds rb CoreDoFullLaziness = _scc_ "FloatOutwards" noStats (floatOutwards us binds) -doCorePass us binds rb CoreDoStaticArgs = _scc_ "StaticArgs" noStats (doStaticArgs us binds) -doCorePass us binds rb CoreDoStrictness = _scc_ "Stranal" noStats (saBinds binds) -doCorePass us binds rb CoreDoWorkerWrapper = _scc_ "WorkWrap" noStats (wwTopBinds us binds) -doCorePass us binds rb CoreDoSpecialising = _scc_ "Specialise" noStats (specProgram us binds) -doCorePass us binds rb CoreDoCPResult = _scc_ "CPResult" noStats (cprAnalyse binds) -doCorePass us binds rb CoreDoPrintCore = _scc_ "PrintCore" noStats (printCore binds) -doCorePass us binds rb CoreDoUSPInf - = _scc_ "CoreUsageSPInf" - if opt_UsageSPOn then - noStats (doUsageSPInf us binds) - else - trace "WARNING: ignoring requested -fusagesp pass; requires -fusagesp-on" $ - noStats (return binds) - -printCore binds = do dumpIfSet True "Print Core" - (pprCoreBindings binds) - return binds - -noStats thing = do { result <- thing; return (zeroSimplCount, result) } -\end{code} - - -%************************************************************************ -%* * -\subsection{Dealing with rules} -%* * -%************************************************************************ - -We must do some gentle simplifiation on the template (but not the RHS) -of each rule. The case that forced me to add this was the fold/build rule, -which without simplification looked like: - fold k z (build (/\a. g a)) ==> ... -This doesn't match unless you do eta reduction on the build argument. - -\begin{code} -simplRules :: UniqSupply -> [ProtoCoreRule] -> [CoreBind] -> IO [ProtoCoreRule] -simplRules us rules binds - = do let (better_rules,_) = initSmpl sw_chkr us bind_vars black_list_all (mapSmpl simplRule rules) - - dumpIfSet opt_D_dump_rules - "Transformation rules" - (vcat (map pprProtoCoreRule better_rules)) - - return better_rules - where - black_list_all v = True -- This stops all inlining - sw_chkr any = SwBool False -- A bit bogus - - -- Boringly, we need to gather the in-scope set. - -- Typically this thunk won't even be force, but the test in - -- simpVar fails if it isn't right, and it might conceivably matter - bind_vars = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds - - -simplRule rule@(ProtoCoreRule is_local id (Rule name bndrs args rhs)) - | not is_local - = returnSmpl rule -- No need to fiddle with imported rules - | otherwise - = simplBinders bndrs $ \ bndrs' -> - mapSmpl simplExpr args `thenSmpl` \ args' -> - simplExpr rhs `thenSmpl` \ rhs' -> - returnSmpl (ProtoCoreRule is_local id (Rule name bndrs' args' rhs')) -\end{code} - -%************************************************************************ -%* * -\subsection{The driver for the simplifier} -%* * -%************************************************************************ - -\begin{code} -simplifyPgm :: RuleBase - -> (SimplifierSwitch -> SwitchResult) - -> UniqSupply - -> [CoreBind] -- Input - -> IO (SimplCount, [CoreBind]) -- New bindings - -simplifyPgm (imported_rule_ids, rule_lhs_fvs) - sw_chkr us binds - = do { - beginPass "Simplify"; - - -- Glom all binds together in one Rec, in case any - -- transformations have introduced any new dependencies - let { recd_binds = [Rec (flattenBinds binds)] }; - - (termination_msg, it_count, counts_out, binds') <- iteration us 1 zeroSimplCount recd_binds; - - dumpIfSet (opt_D_verbose_core2core && opt_D_dump_simpl_stats) - "Simplifier statistics" - (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations", - text "", - pprSimplCount counts_out]); - - endPass "Simplify" - (opt_D_verbose_core2core && not opt_D_dump_simpl_iterations) - binds' ; - - return (counts_out, binds') - } - where - max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations - black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase) - - core_iter_dump binds | opt_D_verbose_core2core = pprCoreBindings binds - | otherwise = empty - - iteration us iteration_no counts binds - = do { - -- Occurrence analysis - let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ; - - dumpIfSet opt_D_dump_occur_anal "Occurrence analysis" - (pprCoreBindings tagged_binds); - - -- Simplify - let { (binds', counts') = initSmpl sw_chkr us1 imported_rule_ids - black_list_fn - (simplTopBinds tagged_binds); - all_counts = counts `plusSimplCount` counts' - } ; - - -- Stop if nothing happened; don't dump output - if isZeroSimplCount counts' then - return ("Simplifier reached fixed point", iteration_no, all_counts, binds') - else do { - - -- Dump the result of this iteration - dumpIfSet opt_D_dump_simpl_iterations - ("Simplifier iteration " ++ show iteration_no - ++ " out of " ++ show max_iterations) - (pprSimplCount counts') ; - - if opt_D_dump_simpl_iterations then - endPass ("Simplifier iteration " ++ show iteration_no ++ " result") - opt_D_verbose_core2core - binds' - else - return [] ; - - -- Stop if we've run out of iterations - if iteration_no == max_iterations then - do { - if max_iterations > 2 then - hPutStr stderr ("NOTE: Simplifier still going after " ++ - show max_iterations ++ - " iterations; bailing out.\n") - else return (); - - return ("Simplifier baled out", iteration_no, all_counts, binds') - } - - -- Else loop - else iteration us2 (iteration_no + 1) all_counts binds' - } } - where - (us1, us2) = splitUniqSupply us -\end{code} - - -%************************************************************************ -%* * -\subsection{PostSimplification} -%* * -%************************************************************************ - -Several tasks are performed by the post-simplification pass - -1. Make the representation of NoRep literals explicit, and - float their bindings to the top level. We only do the floating - part for NoRep lits inside a lambda (else no gain). We need to - take care with let x = "foo" in e - that we don't end up with a silly binding - let x = y in e - with a floated "foo". What a bore. - -2. *Mangle* cases involving par# in the discriminant. The unfolding - for par in PrelConc.lhs include case expressions with integer - results solely to fool the strictness analyzer, the simplifier, - and anyone else who might want to fool with the evaluation order. - At this point in the compiler our evaluation order is safe. - Therefore, we convert expressions of the form: - - case par# e of - 0# -> rhs - _ -> parError# - ==> - case par# e of - _ -> rhs - - fork# isn't handled like this - it's an explicit IO operation now. - The reason is that fork# returns a ThreadId#, which gets in the - way of the above scheme. And anyway, IO is the only guaranteed - way to enforce ordering --SDM. - -4. Do eta reduction for lambda abstractions appearing in: - - the RHS of case alternatives - - the body of a let - - These will otherwise turn into local bindings during Core->STG; - better to nuke them if possible. (In general the simplifier does - eta expansion not eta reduction, up to this point. It does eta - on the RHSs of bindings but not the RHSs of case alternatives and - let bodies) - - -------------------- NOT DONE ANY MORE ------------------------ -[March 98] Indirections are now elimianted by the occurrence analyser -1. Eliminate indirections. The point here is to transform - x_local = E - x_exported = x_local - ==> - x_exported = E - -[Dec 98] [Not now done because there is no penalty in the code - generator for using the former form] -2. Convert - case x of {...; x' -> ...x'...} - ==> - case x of {...; _ -> ...x... } - See notes in SimplCase.lhs, near simplDefault for the reasoning here. --------------------------------------------------------------- - -Special case -~~~~~~~~~~~~ - -NOT ENABLED AT THE MOMENT (because the floated Ids are global-ish -things, and we need local Ids for non-floated stuff): - - Don't float stuff out of a binder that's marked as a bottoming Id. - Reason: it doesn't do any good, and creates more CAFs that increase - the size of SRTs. - -eg. - - f = error "string" - -is translated to - - f' = unpackCString# "string" - f = error f' - -hence f' and f become CAFs. Instead, the special case for -tidyTopBinding below makes sure this comes out as - - f = let f' = unpackCString# "string" in error f' - -and we can safely ignore f as a CAF, since it can only ever be entered once. - - - -\begin{code} -doPostSimplification :: UniqSupply -> [CoreBind] -> IO [CoreBind] -doPostSimplification us binds_in - = do - beginPass "Post-simplification pass" - let binds_out = initPM us (postSimplTopBinds binds_in) - endPass "Post-simplification pass" opt_D_verbose_core2core binds_out - -postSimplTopBinds :: [CoreBind] -> PostM [CoreBind] -postSimplTopBinds binds - = mapPM postSimplTopBind binds `thenPM` \ binds' -> - returnPM (bagToList (unionManyBags binds')) - -postSimplTopBind :: CoreBind -> PostM (Bag CoreBind) -postSimplTopBind (NonRec bndr rhs) - | isBottomingId bndr -- Don't lift out floats for bottoming Ids - -- See notes above - = getFloatsPM (postSimplExpr rhs) `thenPM` \ (rhs', floats) -> - returnPM (unitBag (NonRec bndr (foldrBag Let rhs' floats))) - -postSimplTopBind bind - = getFloatsPM (postSimplBind bind) `thenPM` \ (bind', floats) -> - returnPM (floats `snocBag` bind') - -postSimplBind (NonRec bndr rhs) - = postSimplExpr rhs `thenPM` \ rhs' -> - returnPM (NonRec bndr rhs') - -postSimplBind (Rec pairs) - = mapPM postSimplExpr rhss `thenPM` \ rhss' -> - returnPM (Rec (bndrs `zip` rhss')) - where - (bndrs, rhss) = unzip pairs -\end{code} - - -Expressions -~~~~~~~~~~~ -\begin{code} -postSimplExpr (Var v) = returnPM (Var v) -postSimplExpr (Type ty) = returnPM (Type ty) - -postSimplExpr (App fun arg) - = postSimplExpr fun `thenPM` \ fun' -> - postSimplExpr arg `thenPM` \ arg' -> - returnPM (App fun' arg') - -postSimplExpr (Con (Literal lit) args) - = ASSERT( null args ) - litToRep lit `thenPM` \ (lit_ty, lit_expr) -> - getInsideLambda `thenPM` \ in_lam -> - if in_lam && not (exprIsTrivial lit_expr) then - -- It must have been a no-rep literal with a - -- non-trivial representation; and we're inside a lambda; - -- so float it to the top - addTopFloat lit_ty lit_expr `thenPM` \ v -> - returnPM (Var v) - else - returnPM lit_expr - -postSimplExpr (Con con args) - = mapPM postSimplExpr args `thenPM` \ args' -> - returnPM (Con con args') - -postSimplExpr (Lam bndr body) - = insideLambda bndr $ - postSimplExpr body `thenPM` \ body' -> - returnPM (Lam bndr body') - -postSimplExpr (Let bind body) - = postSimplBind bind `thenPM` \ bind' -> - postSimplExprEta body `thenPM` \ body' -> - returnPM (Let bind' body') - -postSimplExpr (Note note body) - = postSimplExprEta body `thenPM` \ body' -> - returnPM (Note note body') - --- par#: see notes above. -postSimplExpr (Case scrut@(Con (PrimOp op) args) bndr alts) - | funnyParallelOp op && maybeToBool maybe_default - = postSimplExpr scrut `thenPM` \ scrut' -> - postSimplExprEta default_rhs `thenPM` \ rhs' -> - returnPM (Case scrut' bndr [(DEFAULT,[],rhs')]) - where - (other_alts, maybe_default) = findDefault alts - Just default_rhs = maybe_default - -postSimplExpr (Case scrut case_bndr alts) - = postSimplExpr scrut `thenPM` \ scrut' -> - mapPM ps_alt alts `thenPM` \ alts' -> - returnPM (Case scrut' case_bndr alts') - where - ps_alt (con,bndrs,rhs) = postSimplExprEta rhs `thenPM` \ rhs' -> - returnPM (con, bndrs, rhs') - -postSimplExprEta e = postSimplExpr e `thenPM` \ e' -> - returnPM (etaCoreExpr e') -\end{code} - -\begin{code} -funnyParallelOp ParOp = True -funnyParallelOp _ = False -\end{code} - - -%************************************************************************ -%* * -\subsection[coreToStg-lits]{Converting literals} -%* * -%************************************************************************ - -Literals: the NoRep kind need to be de-no-rep'd. -We always replace them with a simple variable, and float a suitable -binding out to the top level. - -\begin{code} -litToRep :: Literal -> PostM (Type, CoreExpr) - -litToRep (NoRepStr s ty) - = returnPM (ty, rhs) - where - rhs = if (any is_NUL (_UNPK_ s)) - - then -- Must cater for NULs in literal string - mkApps (Var unpackCString2Id) - [mkLit (MachStr s), - mkLit (mkMachInt (toInteger (_LENGTH_ s)))] - - else -- No NULs in the string - App (Var unpackCStringId) (mkLit (MachStr s)) - - is_NUL c = c == '\0' -\end{code} - -If an Integer is small enough (Haskell implementations must support -Ints in the range $[-2^29+1, 2^29-1]$), wrap it up in @int2Integer@; -otherwise, wrap with @addr2Integer@. - -\begin{code} -litToRep (NoRepInteger i integer_ty) - = returnPM (integer_ty, rhs) - where - rhs | i > tARGET_MIN_INT && -- Small enough, so start from an Int - i < tARGET_MAX_INT - = Con (DataCon smallIntegerDataCon) [Con (Literal (mkMachInt i)) []] - - | otherwise -- Big, so start from a string - = App (Var addr2IntegerId) (Con (Literal (MachStr (_PK_ (show i)))) []) - - -litToRep (NoRepRational r rational_ty) - = postSimplExpr (mkLit (NoRepInteger (numerator r) integer_ty)) `thenPM` \ num_arg -> - postSimplExpr (mkLit (NoRepInteger (denominator r) integer_ty)) `thenPM` \ denom_arg -> - returnPM (rational_ty, mkConApp ratio_data_con [Type integer_ty, num_arg, denom_arg]) - where - (ratio_data_con, integer_ty) - = case (splitAlgTyConApp_maybe rational_ty) of - Just (tycon, [i_ty], [con]) - -> ASSERT(isIntegerTy i_ty && getUnique tycon == ratioTyConKey) - (con, i_ty) - - _ -> (panic "ratio_data_con", panic "integer_ty") - -litToRep other_lit = returnPM (literalType other_lit, mkLit other_lit) -\end{code} - - -%************************************************************************ -%* * -\subsection{The monad} -%* * -%************************************************************************ - -\begin{code} -type PostM a = Bool -- True <=> inside a *value* lambda - -> (UniqSupply, Bag CoreBind) -- Unique supply and Floats in - -> (a, (UniqSupply, Bag CoreBind)) - -initPM :: UniqSupply -> PostM a -> a -initPM us m - = case m False {- not inside lambda -} (us, emptyBag) of - (result, _) -> result - -returnPM v in_lam usf = (v, usf) -thenPM m k in_lam usf = case m in_lam usf of - (r, usf') -> k r in_lam usf' - -mapPM f [] = returnPM [] -mapPM f (x:xs) = f x `thenPM` \ r -> - mapPM f xs `thenPM` \ rs -> - returnPM (r:rs) - -insideLambda :: CoreBndr -> PostM a -> PostM a -insideLambda bndr m in_lam usf | isId bndr = m True usf - | otherwise = m in_lam usf - -getInsideLambda :: PostM Bool -getInsideLambda in_lam usf = (in_lam, usf) - -getFloatsPM :: PostM a -> PostM (a, Bag CoreBind) -getFloatsPM m in_lam (us, floats) - = let - (a, (us', floats')) = m in_lam (us, emptyBag) - in - ((a, floats'), (us', floats)) - -addTopFloat :: Type -> CoreExpr -> PostM Id -addTopFloat lit_ty lit_rhs in_lam (us, floats) - = let - (us1, us2) = splitUniqSupply us - uniq = uniqFromSupply us1 - lit_id = mkSysLocal SLIT("lf") uniq lit_ty - in - (lit_id, (us2, floats `snocBag` NonRec lit_id lit_rhs)) -\end{code} - - +% +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% +\section[SimplCore]{Driver for simplifying @Core@ programs} + +\begin{code} +module SimplCore ( core2core ) where + +#include "HsVersions.h" + +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SwitchResult(..), switchIsOn, intSwitchSet, + opt_D_dump_occur_anal, opt_D_dump_rules, + opt_D_dump_simpl_iterations, + opt_D_dump_simpl_stats, + opt_D_dump_simpl, opt_D_dump_rules, + opt_D_verbose_core2core, + opt_D_dump_occur_anal, + opt_UsageSPOn, + ) +import CoreLint ( beginPass, endPass ) +import CoreTidy ( tidyCorePgm ) +import CoreSyn +import Rules ( RuleBase, ProtoCoreRule(..), pprProtoCoreRule, prepareRuleBase, orphanRule ) +import CoreUnfold +import PprCore ( pprCoreBindings ) +import OccurAnal ( occurAnalyseBinds ) +import CoreUtils ( exprIsTrivial, coreExprType ) +import Simplify ( simplTopBinds, simplExpr ) +import SimplUtils ( etaCoreExpr, findDefault, simplBinders ) +import SimplMonad +import Const ( Con(..), Literal(..), literalType, mkMachInt ) +import ErrUtils ( dumpIfSet ) +import FloatIn ( floatInwards ) +import FloatOut ( floatOutwards ) +import Id ( Id, mkSysLocal, mkVanillaId, isBottomingId, + idType, setIdType, idName, idInfo, setIdNoDiscard + ) +import VarEnv +import VarSet +import Module ( Module ) +import Name ( mkLocalName, tidyOccName, tidyTopName, + NamedThing(..), OccName + ) +import TyCon ( TyCon, isDataTyCon ) +import PrimOp ( PrimOp(..) ) +import PrelInfo ( unpackCStringId, unpackCString2Id, addr2IntegerId ) +import Type ( Type, splitAlgTyConApp_maybe, + isUnLiftedType, + tidyType, tidyTypes, tidyTopType, tidyTyVar, tidyTyVars, + Type + ) +import TysWiredIn ( smallIntegerDataCon, isIntegerTy ) +import LiberateCase ( liberateCase ) +import SAT ( doStaticArgs ) +import Specialise ( specProgram) +import UsageSPInf ( doUsageSPInf ) +import StrictAnal ( saBinds ) +import WorkWrap ( wwTopBinds ) +import CprAnalyse ( cprAnalyse ) + +import Unique ( Unique, Uniquable(..), + ratioTyConKey + ) +import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply, uniqFromSupply ) +import Constants ( tARGET_MIN_INT, tARGET_MAX_INT ) +import Util ( mapAccumL ) +import SrcLoc ( noSrcLoc ) +import Bag +import Maybes +import IO ( hPutStr, stderr ) +import Outputable + +import Ratio ( numerator, denominator ) +\end{code} + +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ + +\begin{code} +core2core :: [CoreToDo] -- Spec of what core-to-core passes to do + -> [CoreBind] -- Binds in + -> [ProtoCoreRule] -- Rules + -> IO ([CoreBind], [ProtoCoreRule]) + +core2core core_todos binds rules + = do + us <- mkSplitUniqSupply 's' + let (cp_us, us1) = splitUniqSupply us + (ru_us, ps_us) = splitUniqSupply us1 + + better_rules <- simplRules ru_us rules binds + + let (binds1, rule_base) = prepareRuleBase binds better_rules + + -- Do the main business + (stats, processed_binds) <- doCorePasses zeroSimplCount cp_us binds1 + rule_base core_todos + + dumpIfSet opt_D_dump_simpl_stats + "Grand total simplifier statistics" + (pprSimplCount stats) + + -- Do the post-simplification business + post_simpl_binds <- doPostSimplification ps_us processed_binds + + -- Return results + return (post_simpl_binds, filter orphanRule better_rules) + + +doCorePasses stats us binds irs [] + = return (stats, binds) + +doCorePasses stats us binds irs (to_do : to_dos) + = do + let (us1, us2) = splitUniqSupply us + (stats1, binds1) <- doCorePass us1 binds irs to_do + doCorePasses (stats `plusSimplCount` stats1) us2 binds1 irs to_dos + +doCorePass us binds rb (CoreDoSimplify sw_chkr) = _scc_ "Simplify" simplifyPgm rb sw_chkr us binds +doCorePass us binds rb CoreLiberateCase = _scc_ "LiberateCase" noStats (liberateCase binds) +doCorePass us binds rb CoreDoFloatInwards = _scc_ "FloatInwards" noStats (floatInwards binds) +doCorePass us binds rb CoreDoFullLaziness = _scc_ "FloatOutwards" noStats (floatOutwards us binds) +doCorePass us binds rb CoreDoStaticArgs = _scc_ "StaticArgs" noStats (doStaticArgs us binds) +doCorePass us binds rb CoreDoStrictness = _scc_ "Stranal" noStats (saBinds binds) +doCorePass us binds rb CoreDoWorkerWrapper = _scc_ "WorkWrap" noStats (wwTopBinds us binds) +doCorePass us binds rb CoreDoSpecialising = _scc_ "Specialise" noStats (specProgram us binds) +doCorePass us binds rb CoreDoCPResult = _scc_ "CPResult" noStats (cprAnalyse binds) +doCorePass us binds rb CoreDoPrintCore = _scc_ "PrintCore" noStats (printCore binds) +doCorePass us binds rb CoreDoUSPInf + = _scc_ "CoreUsageSPInf" + if opt_UsageSPOn then + noStats (doUsageSPInf us binds) + else + trace "WARNING: ignoring requested -fusagesp pass; requires -fusagesp-on" $ + noStats (return binds) + +printCore binds = do dumpIfSet True "Print Core" + (pprCoreBindings binds) + return binds + +noStats thing = do { result <- thing; return (zeroSimplCount, result) } +\end{code} + + +%************************************************************************ +%* * +\subsection{Dealing with rules} +%* * +%************************************************************************ + +We must do some gentle simplifiation on the template (but not the RHS) +of each rule. The case that forced me to add this was the fold/build rule, +which without simplification looked like: + fold k z (build (/\a. g a)) ==> ... +This doesn't match unless you do eta reduction on the build argument. + +\begin{code} +simplRules :: UniqSupply -> [ProtoCoreRule] -> [CoreBind] -> IO [ProtoCoreRule] +simplRules us rules binds + = do let (better_rules,_) = initSmpl sw_chkr us bind_vars black_list_all (mapSmpl simplRule rules) + + dumpIfSet opt_D_dump_rules + "Transformation rules" + (vcat (map pprProtoCoreRule better_rules)) + + return better_rules + where + black_list_all v = True -- This stops all inlining + sw_chkr any = SwBool False -- A bit bogus + + -- Boringly, we need to gather the in-scope set. + -- Typically this thunk won't even be force, but the test in + -- simpVar fails if it isn't right, and it might conceivably matter + bind_vars = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds + + +simplRule rule@(ProtoCoreRule is_local id (Rule name bndrs args rhs)) + | not is_local + = returnSmpl rule -- No need to fiddle with imported rules + | otherwise + = simplBinders bndrs $ \ bndrs' -> + mapSmpl simplExpr args `thenSmpl` \ args' -> + simplExpr rhs `thenSmpl` \ rhs' -> + returnSmpl (ProtoCoreRule is_local id (Rule name bndrs' args' rhs')) +\end{code} + +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ + +\begin{code} +simplifyPgm :: RuleBase + -> (SimplifierSwitch -> SwitchResult) + -> UniqSupply + -> [CoreBind] -- Input + -> IO (SimplCount, [CoreBind]) -- New bindings + +simplifyPgm (imported_rule_ids, rule_lhs_fvs) + sw_chkr us binds + = do { + beginPass "Simplify"; + + -- Glom all binds together in one Rec, in case any + -- transformations have introduced any new dependencies + let { recd_binds = [Rec (flattenBinds binds)] }; + + (termination_msg, it_count, counts_out, binds') <- iteration us 1 zeroSimplCount recd_binds; + + dumpIfSet (opt_D_verbose_core2core && opt_D_dump_simpl_stats) + "Simplifier statistics" + (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations", + text "", + pprSimplCount counts_out]); + + endPass "Simplify" + (opt_D_verbose_core2core && not opt_D_dump_simpl_iterations) + binds' ; + + return (counts_out, binds') + } + where + max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations + black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase) + + core_iter_dump binds | opt_D_verbose_core2core = pprCoreBindings binds + | otherwise = empty + + iteration us iteration_no counts binds + = do { + -- Occurrence analysis + let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ; + + dumpIfSet opt_D_dump_occur_anal "Occurrence analysis" + (pprCoreBindings tagged_binds); + + -- Simplify + let { (binds', counts') = initSmpl sw_chkr us1 imported_rule_ids + black_list_fn + (simplTopBinds tagged_binds); + all_counts = counts `plusSimplCount` counts' + } ; + + -- Stop if nothing happened; don't dump output + if isZeroSimplCount counts' then + return ("Simplifier reached fixed point", iteration_no, all_counts, binds') + else do { + + -- Dump the result of this iteration + dumpIfSet opt_D_dump_simpl_iterations + ("Simplifier iteration " ++ show iteration_no + ++ " out of " ++ show max_iterations) + (pprSimplCount counts') ; + + if opt_D_dump_simpl_iterations then + endPass ("Simplifier iteration " ++ show iteration_no ++ " result") + opt_D_verbose_core2core + binds' + else + return [] ; + + -- Stop if we've run out of iterations + if iteration_no == max_iterations then + do { + if max_iterations > 2 then + hPutStr stderr ("NOTE: Simplifier still going after " ++ + show max_iterations ++ + " iterations; bailing out.\n") + else return (); + + return ("Simplifier baled out", iteration_no, all_counts, binds') + } + + -- Else loop + else iteration us2 (iteration_no + 1) all_counts binds' + } } + where + (us1, us2) = splitUniqSupply us +\end{code} + + +%************************************************************************ +%* * +\subsection{PostSimplification} +%* * +%************************************************************************ + +Several tasks are performed by the post-simplification pass + +1. Make the representation of NoRep literals explicit, and + float their bindings to the top level. We only do the floating + part for NoRep lits inside a lambda (else no gain). We need to + take care with let x = "foo" in e + that we don't end up with a silly binding + let x = y in e + with a floated "foo". What a bore. + +4. Do eta reduction for lambda abstractions appearing in: + - the RHS of case alternatives + - the body of a let + + These will otherwise turn into local bindings during Core->STG; + better to nuke them if possible. (In general the simplifier does + eta expansion not eta reduction, up to this point. It does eta + on the RHSs of bindings but not the RHSs of case alternatives and + let bodies) + + +------------------- NOT DONE ANY MORE ------------------------ +[March 98] Indirections are now elimianted by the occurrence analyser +1. Eliminate indirections. The point here is to transform + x_local = E + x_exported = x_local + ==> + x_exported = E + +[Dec 98] [Not now done because there is no penalty in the code + generator for using the former form] +2. Convert + case x of {...; x' -> ...x'...} + ==> + case x of {...; _ -> ...x... } + See notes in SimplCase.lhs, near simplDefault for the reasoning here. +-------------------------------------------------------------- + +Special case +~~~~~~~~~~~~ + +NOT ENABLED AT THE MOMENT (because the floated Ids are global-ish +things, and we need local Ids for non-floated stuff): + + Don't float stuff out of a binder that's marked as a bottoming Id. + Reason: it doesn't do any good, and creates more CAFs that increase + the size of SRTs. + +eg. + + f = error "string" + +is translated to + + f' = unpackCString# "string" + f = error f' + +hence f' and f become CAFs. Instead, the special case for +tidyTopBinding below makes sure this comes out as + + f = let f' = unpackCString# "string" in error f' + +and we can safely ignore f as a CAF, since it can only ever be entered once. + + + +\begin{code} +doPostSimplification :: UniqSupply -> [CoreBind] -> IO [CoreBind] +doPostSimplification us binds_in + = do + beginPass "Post-simplification pass" + let binds_out = initPM us (postSimplTopBinds binds_in) + endPass "Post-simplification pass" opt_D_verbose_core2core binds_out + +postSimplTopBinds :: [CoreBind] -> PostM [CoreBind] +postSimplTopBinds binds + = mapPM postSimplTopBind binds `thenPM` \ binds' -> + returnPM (bagToList (unionManyBags binds')) + +postSimplTopBind :: CoreBind -> PostM (Bag CoreBind) +postSimplTopBind (NonRec bndr rhs) + | isBottomingId bndr -- Don't lift out floats for bottoming Ids + -- See notes above + = getFloatsPM (postSimplExpr rhs) `thenPM` \ (rhs', floats) -> + returnPM (unitBag (NonRec bndr (foldrBag Let rhs' floats))) + +postSimplTopBind bind + = getFloatsPM (postSimplBind bind) `thenPM` \ (bind', floats) -> + returnPM (floats `snocBag` bind') + +postSimplBind (NonRec bndr rhs) + = postSimplExpr rhs `thenPM` \ rhs' -> + returnPM (NonRec bndr rhs') + +postSimplBind (Rec pairs) + = mapPM postSimplExpr rhss `thenPM` \ rhss' -> + returnPM (Rec (bndrs `zip` rhss')) + where + (bndrs, rhss) = unzip pairs +\end{code} + + +Expressions +~~~~~~~~~~~ +\begin{code} +postSimplExpr (Var v) = returnPM (Var v) +postSimplExpr (Type ty) = returnPM (Type ty) + +postSimplExpr (App fun arg) + = postSimplExpr fun `thenPM` \ fun' -> + postSimplExpr arg `thenPM` \ arg' -> + returnPM (App fun' arg') + +postSimplExpr (Con (Literal lit) args) + = ASSERT( null args ) + litToRep lit `thenPM` \ (lit_ty, lit_expr) -> + getInsideLambda `thenPM` \ in_lam -> + if in_lam && not (exprIsTrivial lit_expr) then + -- It must have been a no-rep literal with a + -- non-trivial representation; and we're inside a lambda; + -- so float it to the top + addTopFloat lit_ty lit_expr `thenPM` \ v -> + returnPM (Var v) + else + returnPM lit_expr + +postSimplExpr (Con con args) + = mapPM postSimplExpr args `thenPM` \ args' -> + returnPM (Con con args') + +postSimplExpr (Lam bndr body) + = insideLambda bndr $ + postSimplExpr body `thenPM` \ body' -> + returnPM (Lam bndr body') + +postSimplExpr (Let bind body) + = postSimplBind bind `thenPM` \ bind' -> + postSimplExprEta body `thenPM` \ body' -> + returnPM (Let bind' body') + +postSimplExpr (Note note body) + = postSimplExprEta body `thenPM` \ body' -> + returnPM (Note note body') + +postSimplExpr (Case scrut case_bndr alts) + = postSimplExpr scrut `thenPM` \ scrut' -> + mapPM ps_alt alts `thenPM` \ alts' -> + returnPM (Case scrut' case_bndr alts') + where + ps_alt (con,bndrs,rhs) = postSimplExprEta rhs `thenPM` \ rhs' -> + returnPM (con, bndrs, rhs') + +postSimplExprEta e = postSimplExpr e `thenPM` \ e' -> + returnPM (etaCoreExpr e') +\end{code} + + +%************************************************************************ +%* * +\subsection[coreToStg-lits]{Converting literals} +%* * +%************************************************************************ + +Literals: the NoRep kind need to be de-no-rep'd. +We always replace them with a simple variable, and float a suitable +binding out to the top level. + +\begin{code} +litToRep :: Literal -> PostM (Type, CoreExpr) + +litToRep (NoRepStr s ty) + = returnPM (ty, rhs) + where + rhs = if (any is_NUL (_UNPK_ s)) + + then -- Must cater for NULs in literal string + mkApps (Var unpackCString2Id) + [mkLit (MachStr s), + mkLit (mkMachInt (toInteger (_LENGTH_ s)))] + + else -- No NULs in the string + App (Var unpackCStringId) (mkLit (MachStr s)) + + is_NUL c = c == '\0' +\end{code} + +If an Integer is small enough (Haskell implementations must support +Ints in the range $[-2^29+1, 2^29-1]$), wrap it up in @int2Integer@; +otherwise, wrap with @addr2Integer@. + +\begin{code} +litToRep (NoRepInteger i integer_ty) + = returnPM (integer_ty, rhs) + where + rhs | i > tARGET_MIN_INT && -- Small enough, so start from an Int + i < tARGET_MAX_INT + = Con (DataCon smallIntegerDataCon) [Con (Literal (mkMachInt i)) []] + + | otherwise -- Big, so start from a string + = App (Var addr2IntegerId) (Con (Literal (MachStr (_PK_ (show i)))) []) + + +litToRep (NoRepRational r rational_ty) + = postSimplExpr (mkLit (NoRepInteger (numerator r) integer_ty)) `thenPM` \ num_arg -> + postSimplExpr (mkLit (NoRepInteger (denominator r) integer_ty)) `thenPM` \ denom_arg -> + returnPM (rational_ty, mkConApp ratio_data_con [Type integer_ty, num_arg, denom_arg]) + where + (ratio_data_con, integer_ty) + = case (splitAlgTyConApp_maybe rational_ty) of + Just (tycon, [i_ty], [con]) + -> ASSERT(isIntegerTy i_ty && getUnique tycon == ratioTyConKey) + (con, i_ty) + + _ -> (panic "ratio_data_con", panic "integer_ty") + +litToRep other_lit = returnPM (literalType other_lit, mkLit other_lit) +\end{code} + + +%************************************************************************ +%* * +\subsection{The monad} +%* * +%************************************************************************ + +\begin{code} +type PostM a = Bool -- True <=> inside a *value* lambda + -> (UniqSupply, Bag CoreBind) -- Unique supply and Floats in + -> (a, (UniqSupply, Bag CoreBind)) + +initPM :: UniqSupply -> PostM a -> a +initPM us m + = case m False {- not inside lambda -} (us, emptyBag) of + (result, _) -> result + +returnPM v in_lam usf = (v, usf) +thenPM m k in_lam usf = case m in_lam usf of + (r, usf') -> k r in_lam usf' + +mapPM f [] = returnPM [] +mapPM f (x:xs) = f x `thenPM` \ r -> + mapPM f xs `thenPM` \ rs -> + returnPM (r:rs) + +insideLambda :: CoreBndr -> PostM a -> PostM a +insideLambda bndr m in_lam usf | isId bndr = m True usf + | otherwise = m in_lam usf + +getInsideLambda :: PostM Bool +getInsideLambda in_lam usf = (in_lam, usf) + +getFloatsPM :: PostM a -> PostM (a, Bag CoreBind) +getFloatsPM m in_lam (us, floats) + = let + (a, (us', floats')) = m in_lam (us, emptyBag) + in + ((a, floats'), (us', floats)) + +addTopFloat :: Type -> CoreExpr -> PostM Id +addTopFloat lit_ty lit_rhs in_lam (us, floats) + = let + (us1, us2) = splitUniqSupply us + uniq = uniqFromSupply us1 + lit_id = mkSysLocal SLIT("lf") uniq lit_ty + in + (lit_id, (us2, floats `snocBag` NonRec lit_id lit_rhs)) +\end{code} + +