X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=7b9ae306d82ffea3a5d2906ca98a7c5da9d41ef8;hb=f23ba2b294429ccbdeb80f0344ec08f6abf61bb7;hp=c96b21d78c7a50b2d212e6249743394c9628db4f;hpb=d2a5d528fb77bd370791b1a1dc7306a77e8e8889;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index c96b21d..7b9ae30 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -1,768 +1,421 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[SimplCore]{Driver for simplifying @Core@ programs} \begin{code} -#include "HsVersions.h" - module SimplCore ( core2core ) where -IMP_Ubiq(){-uitous-} -IMPORT_1_3(IO(hPutStr,stderr)) - -import AnalFBWW ( analFBWW ) -import Bag ( isEmptyBag, foldBag ) -import BinderInfo ( BinderInfo{-instance Outputable-} ) -import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), switchIsOn, - opt_D_show_passes, - opt_D_simplifier_stats, - opt_D_verbose_core2core, - opt_DoCoreLinting, - opt_FoldrBuildOn, - opt_ReportWhyUnfoldingsDisallowed, - opt_ShowImportSpecs, - opt_LiberateCaseThreshold +#include "HsVersions.h" + +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SwitchResult(..), intSwitchSet, + opt_UsageSPOn, + DynFlags, DynFlag(..), dopt, dopt_CoreToDo ) -import CoreLint ( lintCoreBindings ) +import CoreLint ( showPass, endPass ) import CoreSyn -import CoreUtils ( coreExprType ) -import SimplUtils ( etaCoreExpr, typeOkForCase ) +import CoreFVs ( ruleSomeFreeVars ) +import HscTypes ( PackageRuleBase, HomeSymbolTable, ModDetails(..) ) +import CSE ( cseProgram ) +import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds, + extendRuleBaseList, addRuleBaseFVs ) +import Module ( moduleEnvElts ) import CoreUnfold -import Literal ( Literal(..), literalType, mkMachInt ) -import ErrUtils ( ghcExit ) -import FiniteMap ( FiniteMap ) +import PprCore ( pprCoreBindings, pprIdCoreRule ) +import OccurAnal ( occurAnalyseBinds ) +import CoreUtils ( etaReduceExpr, coreBindsSize ) +import Simplify ( simplTopBinds, simplExpr ) +import SimplUtils ( simplBinders ) +import SimplMonad +import ErrUtils ( dumpIfSet, dumpIfSet_dyn ) import FloatIn ( floatInwards ) import FloatOut ( floatOutwards ) -import FoldrBuildWW ( mkFoldrBuildWW ) -import Id ( mkSysLocal, setIdVisibility, replaceIdInfo, replacePragmaInfo, getIdDemandInfo, idType, - getIdInfo, getPragmaInfo, - nullIdEnv, addOneToIdEnv, delOneFromIdEnv, - lookupIdEnv, SYN_IE(IdEnv), omitIfaceSigForId, - GenId{-instance Outputable-}, SYN_IE(Id) - ) -import IdInfo ( willBeDemanded, DemandInfo ) -import Name ( isExported, isLocallyDefined, SYN_IE(Module), NamedThing(..) ) -import TyCon ( TyCon ) -import PrimOp ( PrimOp(..) ) -import PrelVals ( unpackCStringId, unpackCString2Id, - integerZeroId, integerPlusOneId, - integerPlusTwoId, integerMinusOneId - ) -import Type ( maybeAppDataTyCon, isPrimType, SYN_IE(Type) ) -import TysWiredIn ( stringTy ) +import Id ( Id, isDataConWrapId, setIdNoDiscard ) +import VarSet import LiberateCase ( liberateCase ) -import MagicUFs ( MagicUnfoldingFun ) -import Outputable ( PprStyle(..), Outputable(..){-instance * (,) -} ) -import PprCore -import PprType ( GenType{-instance Outputable-}, GenTyVar{-ditto-} ) -import Pretty ( Doc, vcat, ($$), hsep ) import SAT ( doStaticArgs ) -import SimplMonad ( zeroSimplCount, showSimplCount, SimplCount ) -import SimplPgm ( simplifyPgm ) -import Specialise -import SpecUtils ( pprSpecErrs ) -import StrictAnal ( saWwTopBinds ) -import TyVar ( nullTyVarEnv, GenTyVar{-instance Eq-} ) -import Unique ( integerTyConKey, ratioTyConKey, Unique{-instance Eq-} ) -import UniqFM ( Uniquable(..) ) -import UniqSupply ( splitUniqSupply, getUnique, UniqSupply ) -import Util ( mapAccumL, assertPanic, panic{-ToDo:rm-}, pprTrace, pprPanic ) -import SrcLoc ( noSrcLoc ) -import Constants ( tARGET_MIN_INT, tARGET_MAX_INT ) -import Bag -import Maybes - - -#ifndef OMIT_DEFORESTER -import Deforest ( deforestProgram ) -import DefUtils ( deforestable ) -#endif +import Specialise ( specProgram) +import UsageSPInf ( doUsageSPInf ) +import StrictAnal ( saBinds ) +import WorkWrap ( wwTopBinds ) +import CprAnalyse ( cprAnalyse ) + +import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply ) +import IO ( hPutStr, stderr ) +import Outputable +import List ( partition ) \end{code} -\begin{code} -core2core :: [CoreToDo] -- spec of what core-to-core passes to do - -> FAST_STRING -- module name (profiling only) - -> PprStyle -- printing style (for debugging only) - -> UniqSupply -- a name supply - -> [TyCon] -- local data tycons and tycon specialisations - -> FiniteMap TyCon [(Bool, [Maybe Type])] - -> [CoreBinding] -- input... - -> IO - ([CoreBinding], -- results: program, plus... - SpecialiseData) -- specialisation data - -core2core core_todos module_name ppr_style us local_tycons tycon_specs binds - = -- Print heading - (if opt_D_verbose_core2core then - hPutStr stderr "VERBOSE CORE-TO-CORE:\n" - else return ()) >> - - -- Do the main business - --case (splitUniqSupply us) of { (us1,us2) -> - foldl_mn do_core_pass - (binds, us, init_specdata, zeroSimplCount) - core_todos - >>= \ (processed_binds, us', spec_data, simpl_stats) -> - - -- Do the final tidy-up - let - final_binds = core_linter "TidyCorePgm" True $ - tidyCorePgm module_name us' processed_binds - in - - -- Report statistics - (if opt_D_simplifier_stats then - hPutStr stderr ("\nSimplifier Stats:\n") >> - hPutStr stderr (showSimplCount simpl_stats) >> - hPutStr stderr "\n" - else return ()) >> - - -- - return (final_binds, spec_data) --} - where --- (us1, us2) = splitUniqSupply us - init_specdata = initSpecData local_tycons tycon_specs - - ------------- - core_linter what spec_done - = if opt_DoCoreLinting - then (if opt_D_show_passes then - trace ("\n*** Core Lint result of " ++ what) - else id - ) - lintCoreBindings ppr_style what spec_done - else id - - -------------- - do_core_pass info@(binds, us, spec_data, simpl_stats) to_do = --- let --- (us1, us2) = splitUniqSupply us --- in - case (splitUniqSupply us) of - (us1,us2) -> - case to_do of - CoreDoSimplify simpl_sw_chkr - -> _scc_ "CoreSimplify" - begin_pass ("Simplify" ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild - then " (foldr/build)" else "") >> - case (simplifyPgm binds simpl_sw_chkr simpl_stats us1) of - (p, it_cnt, simpl_stats2) - -> end_pass False us2 p spec_data simpl_stats2 - ("Simplify (" ++ show it_cnt ++ ")" - ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild - then " foldr/build" else "") - - CoreDoFoldrBuildWorkerWrapper - -> _scc_ "CoreDoFoldrBuildWorkerWrapper" - begin_pass "FBWW" >> - case (mkFoldrBuildWW us1 binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "FBWW" } - - CoreDoFoldrBuildWWAnal - -> _scc_ "CoreDoFoldrBuildWWAnal" - begin_pass "AnalFBWW" >> - case (analFBWW binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "AnalFBWW" } - - CoreLiberateCase - -> _scc_ "LiberateCase" - begin_pass "LiberateCase" >> - case (liberateCase opt_LiberateCaseThreshold binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "LiberateCase" } - - CoreDoFloatInwards - -> _scc_ "FloatInwards" - begin_pass "FloatIn" >> - case (floatInwards binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "FloatIn" } - - CoreDoFullLaziness - -> _scc_ "CoreFloating" - begin_pass "FloatOut" >> - case (floatOutwards us1 binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "FloatOut" } - - CoreDoStaticArgs - -> _scc_ "CoreStaticArgs" - begin_pass "StaticArgs" >> - case (doStaticArgs binds us1) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "StaticArgs" } - -- Binds really should be dependency-analysed for static- - -- arg transformation... Not to worry, they probably are. - -- (I don't think it *dies* if they aren't [WDP 94/04/15]) - - CoreDoStrictness - -> _scc_ "CoreStranal" - begin_pass "StrAnal" >> - case (saWwTopBinds us1 binds) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "StrAnal" } - - CoreDoSpecialising - -> _scc_ "Specialise" - begin_pass "Specialise" >> - case (specProgram us1 binds spec_data) of { - (p, spec_data2@(SpecData _ spec_noerrs _ _ _ - spec_errs spec_warn spec_tyerrs)) -> - - -- if we got errors, we die straight away - (if not spec_noerrs || - (opt_ShowImportSpecs && not (isEmptyBag spec_warn)) then - hPutStr stderr (show - (pprSpecErrs module_name spec_errs spec_warn spec_tyerrs)) - >> hPutStr stderr "\n" - else - return ()) >> - - (if not spec_noerrs then -- Stop here if specialisation errors occured - ghcExit 1 - else - return ()) >> - - end_pass False us2 p spec_data2 simpl_stats "Specialise" - } - - CoreDoDeforest -#if OMIT_DEFORESTER - -> error "ERROR: CoreDoDeforest: not built into compiler\n" -#else - -> _scc_ "Deforestation" - begin_pass "Deforestation" >> - case (deforestProgram binds us1) of { binds2 -> - end_pass False us2 binds2 spec_data simpl_stats "Deforestation" } -#endif +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ - CoreDoPrintCore -- print result of last pass - -> end_pass True us2 binds spec_data simpl_stats "Print" - - ------------------------------------------------- - - begin_pass - = if opt_D_show_passes - then \ what -> hPutStr stderr ("*** Core2Core: "++what++"\n") - else \ what -> return () - - end_pass print us2 binds2 - spec_data2@(SpecData spec_done _ _ _ _ _ _ _) - simpl_stats2 what - = -- report verbosely, if required - (if (opt_D_verbose_core2core && not print) || - (print && not opt_D_verbose_core2core) - then - hPutStr stderr ("\n*** "++what++":\n") - >> - hPutStr stderr (show - (vcat (map (pprCoreBinding ppr_style) binds2))) - >> - hPutStr stderr "\n" - else - return ()) >> - let - linted_binds = core_linter what spec_done binds2 - in - return - (linted_binds, -- processed binds, possibly run thru CoreLint - us2, -- UniqueSupply for the next guy - spec_data2, -- possibly-updated specialisation info - simpl_stats2 -- accumulated simplifier stats - ) - --- here so it can be inlined... -foldl_mn f z [] = return z -foldl_mn f z (x:xs) = f z x >>= \ zz -> - foldl_mn f zz xs +\begin{code} +core2core :: DynFlags -- includes spec of what core-to-core passes to do + -> PackageRuleBase -- Rule-base accumulated from imported packages + -> HomeSymbolTable + -> [CoreBind] -- Binds in + -> [IdCoreRule] -- Rules in + -> IO ([CoreBind], [IdCoreRule]) -- binds, local orphan rules out + +core2core dflags pkg_rule_base hst binds rules + = do + let core_todos = dopt_CoreToDo dflags + us <- mkSplitUniqSupply 's' + let (cp_us, ru_us) = splitUniqSupply us + + -- COMPUTE THE RULE BASE TO USE + (rule_base, binds1, orphan_rules) + <- prepareRules dflags pkg_rule_base hst ru_us binds rules + + + -- DO THE BUSINESS + (stats, processed_binds) + <- doCorePasses dflags rule_base (zeroSimplCount dflags) cp_us binds1 core_todos + + dumpIfSet_dyn dflags Opt_D_dump_simpl_stats + "Grand total simplifier statistics" + (pprSimplCount stats) + + -- Return results + -- We only return local orphan rules, i.e., local rules not attached to an Id + -- The bindings cotain more rules, embedded in the Ids + return (processed_binds, orphan_rules) + + +doCorePasses :: DynFlags + -> RuleBase -- the main rule base + -> SimplCount -- simplifier stats + -> UniqSupply -- uniques + -> [CoreBind] -- local binds in (with rules attached) + -> [CoreToDo] -- which passes to do + -> IO (SimplCount, [CoreBind]) -- stats, binds, local orphan rules + +doCorePasses dflags rb stats us binds [] + = return (stats, binds) + +doCorePasses dflags rb stats us binds (to_do : to_dos) + = do + let (us1, us2) = splitUniqSupply us + + (stats1, binds1) <- doCorePass dflags rb us1 binds to_do + + doCorePasses dflags rb (stats `plusSimplCount` stats1) us2 binds1 to_dos + +doCorePass dfs rb us binds (CoreDoSimplify sw_chkr) + = _scc_ "Simplify" simplifyPgm dfs rb sw_chkr us binds +doCorePass dfs rb us binds CoreCSE + = _scc_ "CommonSubExpr" noStats dfs (cseProgram dfs binds) +doCorePass dfs rb us binds CoreLiberateCase + = _scc_ "LiberateCase" noStats dfs (liberateCase dfs binds) +doCorePass dfs rb us binds CoreDoFloatInwards + = _scc_ "FloatInwards" noStats dfs (floatInwards dfs binds) +doCorePass dfs rb us binds (CoreDoFloatOutwards f) + = _scc_ "FloatOutwards" noStats dfs (floatOutwards dfs f us binds) +doCorePass dfs rb us binds CoreDoStaticArgs + = _scc_ "StaticArgs" noStats dfs (doStaticArgs us binds) +doCorePass dfs rb us binds CoreDoStrictness + = _scc_ "Stranal" noStats dfs (saBinds dfs binds) +doCorePass dfs rb us binds CoreDoWorkerWrapper + = _scc_ "WorkWrap" noStats dfs (wwTopBinds dfs us binds) +doCorePass dfs rb us binds CoreDoSpecialising + = _scc_ "Specialise" noStats dfs (specProgram dfs us binds) +doCorePass dfs rb us binds CoreDoCPResult + = _scc_ "CPResult" noStats dfs (cprAnalyse dfs binds) +doCorePass dfs rb us binds CoreDoPrintCore + = _scc_ "PrintCore" noStats dfs (printCore binds) +doCorePass dfs rb us binds CoreDoUSPInf + = _scc_ "CoreUsageSPInf" noStats dfs (doUsageSPInf dfs us binds) +doCorePass dfs rb us binds CoreDoGlomBinds + = noStats dfs (glomBinds dfs binds) +doCorePass dfs rb us binds CoreDoNothing + = noStats dfs (return binds) + +printCore binds = do dumpIfSet True "Print Core" + (pprCoreBindings binds) + return binds + +-- most passes return no stats and don't change rules +noStats dfs thing = do { binds <- thing; return (zeroSimplCount dfs, binds) } \end{code} %************************************************************************ %* * -\subsection[SimplCore-indirections]{Eliminating indirections in Core code, and globalising} +\subsection{Dealing with rules} %* * %************************************************************************ -Several tasks are done by @tidyCorePgm@ - -1. Eliminate indirections. The point here is to transform - x_local = E - x_exported = x_local - ==> - x_exported = E - -2. Make certain top-level bindings into Globals. The point is that - Global things get externally-visible labels at code generation - time - -3. Make the representation of NoRep literals explicit, and - float their bindings to the top level - -4. Convert - case x of {...; x' -> ...x'...} - ==> - case x of {...; _ -> ...x... } - See notes in SimplCase.lhs, near simplDefault for the reasoning here. - -5. *Mangle* cases involving fork# and par# in the discriminant. The - original templates for these primops (see @PrelVals.lhs@) constructed - case expressions with boolean 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 - True -> rhs - False -> parError# - ==> - case par# e of - _ -> rhs - -6. Eliminate polymorphic case expressions. We can't generate code for them yet. - -7. 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.) - -8. Do let-to-case. See notes in Simplify.lhs for why we defer let-to-case - for multi-constructor types. - - -Eliminate indirections -~~~~~~~~~~~~~~~~~~~~~~ -In @elimIndirections@, we look for things at the top-level of the form... -\begin{verbatim} - x_local = .... - x_exported = x_local -\end{verbatim} -In cases we find like this, we go {\em backwards} and replace -\tr{x_local} with \tr{x_exported}. This save a gratuitous jump -(from \tr{x_exported} to \tr{x_local}), and makes strictness -information propagate better. - -We rely on prior eta reduction to simplify things like -\begin{verbatim} - x_exported = /\ tyvars -> x_local tyvars -==> - x_exported = x_local -\end{verbatim} - -If more than one exported thing is equal to a local thing (i.e., the -local thing really is shared), then we do one only: -\begin{verbatim} - x_local = .... - x_exported1 = x_local - x_exported2 = x_local -==> - x_exported1 = .... - - x_exported2 = x_exported1 -\end{verbatim} - -There's a possibility of leaving unchanged something like this: -\begin{verbatim} - x_local = .... - x_exported1 = x_local Int -\end{verbatim} -By the time we've thrown away the types in STG land this -could be eliminated. But I don't think it's very common -and it's dangerous to do this fiddling in STG land -because we might elminate a binding that's mentioned in the -unfolding for something. - -General Strategy: first collect the info; then make a \tr{Id -> Id} mapping. -Then blast the whole program (LHSs as well as RHSs) with it. - +-- prepareLocalRuleBase takes the CoreBinds and rules defined in this module. +-- It attaches those rules that are for local Ids to their binders, and +-- returns the remainder attached to Ids in an IdSet. It also returns +-- Ids mentioned on LHS of some rule; these should be blacklisted. +-- The rule Ids and LHS Ids are black-listed; that is, they aren't inlined +-- so that the opportunity to apply the rule isn't lost too soon \begin{code} -tidyCorePgm :: Module -> UniqSupply -> [CoreBinding] -> [CoreBinding] - -tidyCorePgm mod us binds_in - = initTM mod indirection_env us $ - tidyTopBindings (catMaybes reduced_binds) `thenTM` \ binds -> - returnTM (bagToList binds) +prepareRules :: DynFlags -> PackageRuleBase -> HomeSymbolTable + -> UniqSupply + -> [CoreBind] -> [IdCoreRule] -- Local bindings and rules + -> IO (RuleBase, -- Full rule base + [CoreBind], -- Bindings augmented with rules + [IdCoreRule]) -- Orphan rules + +prepareRules dflags pkg_rule_base hst us binds rules + = do { let (better_rules,_) = initSmpl dflags sw_chkr us local_ids black_list_all + (mapSmpl simplRule rules) + + ; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules" + (vcat (map pprIdCoreRule better_rules)) + + ; let (local_id_rules, orphan_rules) = partition ((`elemVarSet` local_ids) . fst) better_rules + (binds1, local_rule_fvs) = addRulesToBinds binds local_id_rules + imp_rule_base = foldl add_rules pkg_rule_base (moduleEnvElts hst) + rule_base = extendRuleBaseList imp_rule_base orphan_rules + final_rule_base = addRuleBaseFVs rule_base local_rule_fvs + -- The last step black-lists the free vars of local rules too + + ; return (final_rule_base, binds1, orphan_rules) + } where - (indirection_env, reduced_binds) = mapAccumL try_bind nullIdEnv binds_in - - try_bind :: IdEnv Id -> CoreBinding -> (IdEnv Id, Maybe CoreBinding) - try_bind env_so_far (NonRec exported_binder rhs) - | isExported exported_binder && -- Only if this is exported - maybeToBool maybe_rhs_id && -- and the RHS is a simple Id - - isLocallyDefined rhs_id && -- Only if this one is defined in this - -- module, so that we *can* change its - -- binding to be the exported thing! - - not (isExported rhs_id) && -- Only if this one is not itself exported, - -- since the transformation will nuke it - - not (omitIfaceSigForId rhs_id) && -- Don't do the transformation if rhs_id is - -- something like a constructor, whose - -- definition is implicitly exported and - -- which must not vanish. - -- To illustrate the preceding check consider - -- data T = MkT Int - -- mkT = MkT - -- f x = MkT (x+1) - -- Here, we'll make a local, non-exported, defn for MkT, and without the - -- above condition we'll transform it to: - -- mkT = \x. MkT [x] - -- f = \y. mkT (y+1) - -- This is bad because mkT will get the IdDetails of MkT, and won't - -- be exported. Also the code generator won't make a definition for - -- the MkT constructor. - -- Slightly gruesome, this. - - not (maybeToBool (lookupIdEnv env_so_far rhs_id)) - -- Only if not already substituted for - - = (addOneToIdEnv env_so_far rhs_id new_rhs_id, Nothing) - where - maybe_rhs_id = case etaCoreExpr rhs of - Var rhs_id -> Just rhs_id - other -> Nothing - Just rhs_id = maybe_rhs_id - new_rhs_id = exported_binder `replaceIdInfo` getIdInfo rhs_id - `replacePragmaInfo` getPragmaInfo rhs_id - -- NB: we keep the Pragmas and IdInfo for the old rhs_id! - -- This is important; it might be marked "no-inline" by - -- the occurrence analyser (because it's recursive), and - -- we must not lose that information. - - try_bind env_so_far bind - = (env_so_far, Just bind) -\end{code} - -Top level bindings -~~~~~~~~~~~~~~~~~~ -\begin{code} -tidyTopBindings [] = returnTM emptyBag -tidyTopBindings (b:bs) - = tidyTopBinding b $ - tidyTopBindings bs - -tidyTopBinding :: CoreBinding - -> TidyM (Bag CoreBinding) - -> TidyM (Bag CoreBinding) - -tidyTopBinding (NonRec bndr rhs) thing_inside - = getFloats (tidyCoreExpr rhs) `thenTM` \ (rhs',floats) -> - mungeTopBinder bndr $ \ bndr' -> - thing_inside `thenTM` \ binds -> - returnTM ((floats `snocBag` NonRec bndr' rhs') `unionBags` binds) - -tidyTopBinding (Rec pairs) thing_inside - = mungeTopBinders binders $ \ binders' -> - getFloats (mapTM tidyCoreExpr rhss) `thenTM` \ (rhss', floats) -> - thing_inside `thenTM` \ binds_inside -> - returnTM ((floats `snocBag` Rec (binders' `zip` rhss')) `unionBags` binds_inside) + sw_chkr any = SwBool False -- A bit bogus + black_list_all v = not (isDataConWrapId v) + -- This stops all inlining except the + -- wrappers for data constructors + + add_rules rule_base mds = extendRuleBaseList rule_base (md_rules mds) + + -- Boringly, we need to gather the in-scope set. + -- Typically this thunk won't even be forced, but the test in + -- simpVar fails if it isn't right, and it might conceiveably matter + local_ids = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds + +addRulesToBinds :: [CoreBind] -> [(Id,CoreRule)] -> ([CoreBind], IdSet) + -- A horrible function + + -- Attach the rules for each locally-defined Id to that Id. + -- - This makes the rules easier to look up + -- - It means that transformation rules and specialisations for + -- locally defined Ids are handled uniformly + -- - It keeps alive things that are referred to only from a rule + -- (the occurrence analyser knows about rules attached to Ids) + -- - It makes sure that, when we apply a rule, the free vars + -- of the RHS are more likely to be in scope + -- + -- Both the LHS and RHS Ids are marked 'no-discard'. + -- This means that the binding won't be discarded EVEN if the binding + -- ends up being trivial (v = w) -- the simplifier would usually just + -- substitute w for v throughout, but we don't apply the substitution to + -- the rules (maybe we should?), so this substitution would make the rule + -- bogus. + +addRulesToBinds binds local_rules + = (map zap_bind binds, rule_lhs_fvs) where - (binders, rhss) = unzip pairs -\end{code} - + -- rule_fvs is the set of all variables mentioned in this module's rules + rule_fvs = unionVarSets [ ruleSomeFreeVars isId rule | (_,rule) <- local_rules ] -Local Bindings -~~~~~~~~~~~~~~ -\begin{code} -tidyCoreBinding (NonRec bndr rhs) - = tidyCoreExpr rhs `thenTM` \ rhs' -> - returnTM (NonRec bndr rhs') + rule_base = extendRuleBaseList emptyRuleBase local_rules + rule_lhs_fvs = ruleBaseFVs rule_base + rule_ids = ruleBaseIds rule_base -tidyCoreBinding (Rec pairs) - = mapTM do_one pairs `thenTM` \ pairs' -> - returnTM (Rec pairs') - where - do_one (bndr,rhs) = tidyCoreExpr rhs `thenTM` \ rhs' -> - returnTM (bndr, rhs') + zap_bind (NonRec b r) = NonRec (zap_bndr b) r + zap_bind (Rec prs) = Rec [(zap_bndr b, r) | (b,r) <- prs] + zap_bndr bndr = case lookupVarSet rule_ids bndr of + Just bndr' -> setIdNoDiscard bndr' + Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr + | otherwise -> bndr \end{code} -Expressions -~~~~~~~~~~~ -\begin{code} -tidyCoreExpr (Var v) = lookupTM v `thenTM` \ v' -> - returnTM (Var v') - -tidyCoreExpr (Lit lit) - = litToRep lit `thenTM` \ (_, lit_expr) -> - returnTM lit_expr - -tidyCoreExpr (App fun arg) - = tidyCoreExpr fun `thenTM` \ fun' -> - tidyCoreArg arg `thenTM` \ arg' -> - returnTM (App fun' arg') - -tidyCoreExpr (Con con args) - = mapTM tidyCoreArg args `thenTM` \ args' -> - returnTM (Con con args') - -tidyCoreExpr (Prim prim args) - = mapTM tidyCoreArg args `thenTM` \ args' -> - returnTM (Prim prim args') - -tidyCoreExpr (Lam bndr body) - = tidyCoreExpr body `thenTM` \ body' -> - returnTM (Lam bndr body') - - -- Try for let-to-case (see notes in Simplify.lhs for why - -- some let-to-case stuff is deferred to now). -tidyCoreExpr (Let (NonRec bndr rhs) body) - | willBeDemanded (getIdDemandInfo bndr) && - typeOkForCase (idType bndr) - = ASSERT( not (isPrimType (idType bndr)) ) - tidyCoreExpr (Case rhs (AlgAlts [] (BindDefault bndr body))) - -tidyCoreExpr (Let bind body) - = tidyCoreBinding bind `thenTM` \ bind' -> - tidyCoreExprEta body `thenTM` \ body' -> - returnTM (Let bind' body') - -tidyCoreExpr (SCC cc body) - = tidyCoreExprEta body `thenTM` \ body' -> - returnTM (SCC cc body') - -tidyCoreExpr (Coerce coercion ty body) - = tidyCoreExprEta body `thenTM` \ body' -> - returnTM (Coerce coercion ty body') - --- Wierd case for par, seq, fork etc. See notes above. -tidyCoreExpr (Case scrut@(Prim op args) (PrimAlts _ (BindDefault binder rhs))) - | funnyParallelOp op - = tidyCoreExpr scrut `thenTM` \ scrut' -> - tidyCoreExprEta rhs `thenTM` \ rhs' -> - returnTM (Case scrut' (PrimAlts [] (BindDefault binder rhs'))) - --- Eliminate polymorphic case, for which we can't generate code just yet -tidyCoreExpr (Case scrut (AlgAlts [] (BindDefault deflt_bndr rhs))) - | not (typeOkForCase (idType deflt_bndr)) - = pprTrace "Warning: discarding polymorphic case:" (ppr PprDebug scrut) $ - case scrut of - Var v -> extendEnvTM deflt_bndr v (tidyCoreExpr rhs) - other -> tidyCoreExpr (Let (NonRec deflt_bndr scrut) rhs) - -tidyCoreExpr (Case scrut alts) - = tidyCoreExpr scrut `thenTM` \ scrut' -> - tidy_alts scrut' alts `thenTM` \ alts' -> - returnTM (Case scrut' alts') - where - tidy_alts scrut (AlgAlts alts deflt) - = mapTM tidy_alg_alt alts `thenTM` \ alts' -> - tidy_deflt scrut deflt `thenTM` \ deflt' -> - returnTM (AlgAlts alts' deflt') - - tidy_alts scrut (PrimAlts alts deflt) - = mapTM tidy_prim_alt alts `thenTM` \ alts' -> - tidy_deflt scrut deflt `thenTM` \ deflt' -> - returnTM (PrimAlts alts' deflt') - - tidy_alg_alt (con,bndrs,rhs) = tidyCoreExprEta rhs `thenTM` \ rhs' -> - returnTM (con,bndrs,rhs') - - tidy_prim_alt (lit,rhs) = tidyCoreExprEta rhs `thenTM` \ rhs' -> - returnTM (lit,rhs') - - -- We convert case x of {...; x' -> ...x'...} - -- to - -- case x of {...; _ -> ...x... } - -- - -- See notes in SimplCase.lhs, near simplDefault for the reasoning. - -- It's quite easily done: simply extend the environment to bind the - -- default binder to the scrutinee. - - tidy_deflt scrut NoDefault = returnTM NoDefault - tidy_deflt scrut (BindDefault bndr rhs) - = extend_env (tidyCoreExprEta rhs) `thenTM` \ rhs' -> - returnTM (BindDefault bndr rhs') - where - extend_env = case scrut of - Var v -> extendEnvTM bndr v - other -> \x -> x - -tidyCoreExprEta e = tidyCoreExpr e `thenTM` \ e' -> - returnTM (etaCoreExpr e') -\end{code} +We must do some gentle simplification 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. -Arguments -~~~~~~~~~ \begin{code} -tidyCoreArg :: CoreArg -> TidyM CoreArg - -tidyCoreArg (VarArg v) - = lookupTM v `thenTM` \ v' -> - returnTM (VarArg v') - -tidyCoreArg (LitArg lit) - = litToRep lit `thenTM` \ (lit_ty, lit_expr) -> - case lit_expr of - Var v -> returnTM (VarArg v) - Lit l -> returnTM (LitArg l) - other -> addTopFloat lit_ty lit_expr `thenTM` \ v -> - returnTM (VarArg v) - -tidyCoreArg (TyArg ty) = returnTM (TyArg ty) -tidyCoreArg (UsageArg u) = returnTM (UsageArg u) +simplRule rule@(id, BuiltinRule _) + = returnSmpl rule +simplRule rule@(id, Rule name bndrs args rhs) + = simplBinders bndrs $ \ bndrs' -> + mapSmpl simpl_arg args `thenSmpl` \ args' -> + simplExpr rhs `thenSmpl` \ rhs' -> + returnSmpl (id, Rule name bndrs' args' rhs') + +simpl_arg e +-- I've seen rules in which a LHS like +-- augment g (build h) +-- turns into +-- augment (\a. g a) (build h) +-- So it's a help to eta-reduce the args as we simplify them. +-- Otherwise we don't match when given an argument like +-- (\a. h a a) + = simplExpr e `thenSmpl` \ e' -> + returnSmpl (etaReduceExpr e') \end{code} %************************************************************************ %* * -\subsection[coreToStg-lits]{Converting literals} +\subsection{Glomming} %* * %************************************************************************ -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 -> TidyM (Type, CoreExpr) - -litToRep (NoRepStr s) - = returnTM (stringTy, rhs) - where - rhs = if (any is_NUL (_UNPK_ s)) - - then -- Must cater for NULs in literal string - mkGenApp (Var unpackCString2Id) - [LitArg (MachStr s), - LitArg (mkMachInt (toInteger (_LENGTH_ s)))] - - else -- No NULs in the string - App (Var unpackCStringId) (LitArg (MachStr s)) - - is_NUL c = c == '\0' +glomBinds :: DynFlags -> [CoreBind] -> IO [CoreBind] +-- Glom all binds together in one Rec, in case any +-- transformations have introduced any new dependencies +-- +-- NB: the global invariant is this: +-- *** the top level bindings are never cloned, and are always unique *** +-- +-- We sort them into dependency order, but applying transformation rules may +-- make something at the top refer to something at the bottom: +-- f = \x -> p (q x) +-- h = \y -> 3 +-- +-- RULE: p (q x) = h x +-- +-- Applying this rule makes f refer to h, +-- although it doesn't appear to in the source program. +-- This pass lets us control where it happens. +-- +-- NOTICE that this cannot happen for rules whose head is a locally-defined +-- function. It only happens for rules whose head is an imported function +-- (p in the example above). So, for example, the rule had been +-- RULE: f (p x) = h x +-- then the rule for f would be attached to f itself (in its IdInfo) +-- by prepareLocalRuleBase and h would be regarded by the occurrency +-- analyser as free in f. + +glomBinds dflags binds + = do { showPass dflags "GlomBinds" ; + let { recd_binds = [Rec (flattenBinds binds)] } ; + return recd_binds } + -- Not much point in printing the result... + -- just consumes output bandwidth \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 @litString2Integer@. - -\begin{code} -litToRep (NoRepInteger i integer_ty) - = returnTM (integer_ty, rhs) - where - rhs | i == 0 = Var integerZeroId -- Extremely convenient to look out for - | i == 1 = Var integerPlusOneId -- a few very common Integer literals! - | i == 2 = Var integerPlusTwoId - | i == (-1) = Var integerMinusOneId - - | i > tARGET_MIN_INT && -- Small enough, so start from an Int - i < tARGET_MAX_INT - = Prim Int2IntegerOp [LitArg (mkMachInt i)] - - | otherwise -- Big, so start from a string - = Prim Addr2IntegerOp [LitArg (MachStr (_PK_ (show i)))] - - -litToRep (NoRepRational r rational_ty) - = tidyCoreArg (LitArg (NoRepInteger (numerator r) integer_ty)) `thenTM` \ num_arg -> - tidyCoreArg (LitArg (NoRepInteger (denominator r) integer_ty)) `thenTM` \ denom_arg -> - returnTM (rational_ty, Con ratio_data_con [TyArg integer_ty, num_arg, denom_arg]) - where - (ratio_data_con, integer_ty) - = case (maybeAppDataTyCon rational_ty) of - Just (tycon, [i_ty], [con]) - -> ASSERT(is_integer_ty i_ty && uniqueOf tycon == ratioTyConKey) - (con, i_ty) - - _ -> (panic "ratio_data_con", panic "integer_ty") - - is_integer_ty ty - = case (maybeAppDataTyCon ty) of - Just (tycon, [], _) -> uniqueOf tycon == integerTyConKey - _ -> False - -litToRep other_lit = returnTM (literalType other_lit, Lit other_lit) -\end{code} - -\begin{code} -funnyParallelOp SeqOp = True -funnyParallelOp ParOp = True -funnyParallelOp ForkOp = True -funnyParallelOp _ = False -\end{code} - %************************************************************************ %* * -\subsection{The monad} +\subsection{The driver for the simplifier} %* * %************************************************************************ \begin{code} -type TidyM a = Module - -> IdEnv Id - -> (UniqSupply, Bag CoreBinding) - -> (a, (UniqSupply, Bag CoreBinding)) - -initTM mod env us m - = case m mod env (us,emptyBag) of - (result, (us',floats)) -> result - -returnTM v mod env usf = (v, usf) -thenTM m k mod env usf = case m mod env usf of - (r, usf') -> k r mod env usf' - -mapTM f [] = returnTM [] -mapTM f (x:xs) = f x `thenTM` \ r -> - mapTM f xs `thenTM` \ rs -> - returnTM (r:rs) -\end{code} - - -\begin{code} -getFloats :: TidyM a -> TidyM (a, Bag CoreBinding) -getFloats m mod env (us,floats) - = case m mod env (us,emptyBag) of - (r, (us',floats')) -> ((r, floats'), (us',floats)) - - --- Need to extend the environment when we munge a binder, so that occurrences --- of the binder will print the correct way (i.e. as a global not a local) -mungeTopBinder :: Id -> (Id -> TidyM a) -> TidyM a -mungeTopBinder id thing_inside mod env usf - = case lookupIdEnv env id of - Just global -> thing_inside global mod env usf - Nothing -> thing_inside new_global mod new_env usf - where - new_env = addOneToIdEnv env id new_global - new_global = setIdVisibility mod id - -mungeTopBinders [] k = k [] -mungeTopBinders (b:bs) k = mungeTopBinder b $ \ b' -> - mungeTopBinders bs $ \ bs' -> - k (b' : bs') - -addTopFloat :: Type -> CoreExpr -> TidyM Id -addTopFloat lit_ty lit_rhs mod env (us, floats) - = case splitUniqSupply us of - (us',us1) -> - let - lit_local = mkSysLocal SLIT("nrlit") uniq lit_ty noSrcLoc - lit_id = setIdVisibility mod lit_local - --(us', us1) = splitUniqSupply us - uniq = getUnique us1 - in - (lit_id, (us', floats `snocBag` NonRec lit_id lit_rhs)) -{- +simplifyPgm :: DynFlags + -> RuleBase + -> (SimplifierSwitch -> SwitchResult) + -> UniqSupply + -> [CoreBind] -- Input + -> IO (SimplCount, [CoreBind]) -- New bindings + +simplifyPgm dflags rule_base + sw_chkr us binds + = do { + showPass dflags "Simplify"; + + (termination_msg, it_count, counts_out, binds') + <- iteration us 1 (zeroSimplCount dflags) binds; + + dumpIfSet (dopt Opt_D_verbose_core2core dflags + && dopt Opt_D_dump_simpl_stats dflags) + "Simplifier statistics" + (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations", + text "", + pprSimplCount counts_out]); + + endPass dflags "Simplify" + (dopt Opt_D_verbose_core2core dflags + && not (dopt Opt_D_dump_simpl_iterations dflags)) + binds' ; + + return (counts_out, binds') + } where - lit_local = mkSysLocal SLIT("nrlit") uniq lit_ty noSrcLoc - lit_id = setIdVisibility mod lit_local - (us', us1) = splitUniqSupply us - uniq = getUnique us1 --} -lookupTM v mod env usf - = case lookupIdEnv env v of - Nothing -> (v, usf) - Just v' -> (v', usf) - -extendEnvTM v v' m mod env usf - = m mod (addOneToIdEnv env v v') usf -\end{code} + max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations + black_list_fn = blackListed rule_lhs_fvs (intSwitchSet sw_chkr SimplInlinePhase) + imported_rule_ids = ruleBaseIds rule_base + rule_lhs_fvs = ruleBaseFVs rule_base + + iteration us iteration_no counts binds + -- Try and force thunks off the binds; significantly reduces + -- space usage, especially with -O. JRS, 000620. + | let sz = coreBindsSize binds in sz == sz + = do { + -- Occurrence analysis + let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds binds } ; + + dumpIfSet_dyn dflags Opt_D_dump_occur_anal "Occurrence analysis" + (pprCoreBindings tagged_binds); + + -- SIMPLIFY + -- We do this with a *case* not a *let* because lazy pattern + -- matching bit us with bad space leak! + -- With a let, we ended up with + -- let + -- t = initSmpl ... + -- counts' = snd t + -- in + -- case t of {(_,counts') -> if counts'=0 then ... + -- So the conditional didn't force counts', because the + -- selection got duplicated. Sigh! + case initSmpl dflags sw_chkr us1 imported_rule_ids black_list_fn + (simplTopBinds tagged_binds) + of { (binds', counts') -> do { + -- The imported_rule_ids are used by initSmpl to initialise + -- the in-scope set. That way, the simplifier will change any + -- occurrences of the imported id to the one in the imported_rule_ids + -- set, which are decorated with their rules. + + let { 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_dyn dflags Opt_D_dump_simpl_iterations + ("Simplifier iteration " ++ show iteration_no + ++ " out of " ++ show max_iterations) + (pprSimplCount counts') ; + + if dopt Opt_D_dump_simpl_iterations dflags then + endPass dflags + ("Simplifier iteration " ++ show iteration_no ++ " result") + (dopt Opt_D_verbose_core2core dflags) + binds' + else + return [] ; + + -- Stop if we've run out of iterations + if iteration_no == max_iterations then + do { +#ifdef DEBUG + if max_iterations > 2 then + hPutStr stderr ("NOTE: Simplifier still going after " ++ + show max_iterations ++ + " iterations; bailing out.\n") + else +#endif + 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}