X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=c7e484fc99aa1d5d575d4955b35bbf5bbd94ea0b;hb=957bf3756ffd56f5329a2aabe1022d6f996dd641;hp=8a122ef9ba2259b4e2713f673cfa1380aaa52e9d;hpb=a6c7e7dc8d0c5626ea29c71c3fc957d33064697b;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index 8a122ef..c7e484f 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -1,836 +1,525 @@ % -% (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} +module SimplCore ( core2core, simplifyExpr ) where + #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_dump_simpl, - opt_D_verbose_core2core, - opt_DoCoreLinting, - opt_FoldrBuildOn, - opt_ReportWhyUnfoldingsDisallowed, - opt_ShowImportSpecs, - opt_LiberateCaseThreshold +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SimplifierMode(..), DynFlags, DynFlag(..), dopt, + dopt_CoreToDo ) -import CoreLint ( lintCoreBindings ) import CoreSyn -import CoreUtils ( coreExprType ) -import SimplUtils ( etaCoreExpr, typeOkForCase ) -import CoreUnfold -import Literal ( Literal(..), literalType, mkMachInt ) -import ErrUtils ( ghcExit, dumpIfSet, doIfSet ) -import FiniteMap ( FiniteMap ) +import CoreFVs ( ruleRhsFreeVars ) +import HscTypes ( PersistentCompilerState(..), ExternalPackageState(..), + HscEnv(..), GhciMode(..), + ModGuts(..), ModGuts, Avails, availsToNameSet, + PackageRuleBase, HomePackageTable, ModDetails(..), + HomeModInfo(..) + ) +import CSE ( cseProgram ) +import Rules ( RuleBase, emptyRuleBase, ruleBaseFVs, ruleBaseIds, + extendRuleBaseList, addRuleBaseFVs, pprRuleBase, + ruleCheckProgram ) +import Module ( moduleEnvElts ) +import Name ( Name, isExternalName ) +import NameSet ( elemNameSet ) +import PprCore ( pprCoreBindings, pprCoreExpr ) +import OccurAnal ( occurAnalyseBinds, occurAnalyseGlobalExpr ) +import CoreUtils ( coreBindsSize ) +import Simplify ( simplTopBinds, simplExpr ) +import SimplUtils ( simplBinders ) +import SimplMonad +import ErrUtils ( dumpIfSet, dumpIfSet_dyn, showPass ) +import CoreLint ( endPass ) import FloatIn ( floatInwards ) import FloatOut ( floatOutwards ) -import FoldrBuildWW ( mkFoldrBuildWW ) -import Id ( mkSysLocal, setIdVisibility, replaceIdInfo, - replacePragmaInfo, getIdDemandInfo, idType, - getIdInfo, getPragmaInfo, mkIdWithNewUniq, - nullIdEnv, addOneToIdEnv, delOneFromIdEnv, - lookupIdEnv, SYN_IE(IdEnv), omitIfaceSigForId, - apply_to_Id, - GenId{-instance Outputable-}, SYN_IE(Id) - ) -import IdInfo ( willBeDemanded, DemandInfo ) -import Name ( isExported, isLocallyDefined, - isLocalName, uniqToOccName, - SYN_IE(Module), NamedThing(..), OccName(..) - ) -import TyCon ( TyCon ) -import PrimOp ( PrimOp(..) ) -import PrelVals ( unpackCStringId, unpackCString2Id, - integerZeroId, integerPlusOneId, - integerPlusTwoId, integerMinusOneId - ) -import Type ( maybeAppDataTyCon, isPrimType, SYN_IE(Type) ) -import TysWiredIn ( stringTy, isIntegerTy ) +import Id ( idName, setIdLocalExported ) +import VarSet import LiberateCase ( liberateCase ) -import MagicUFs ( MagicUnfoldingFun ) -import Outputable ( pprDumpStyle, printErrs, - PprStyle(..), Outputable(..){-instance * (,) -} - ) -import PprCore -import PprType ( GenType{-instance Outputable-}, GenTyVar{-ditto-}, - nmbrType - ) -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 ( SYN_IE(TyVar), nullTyVarEnv, GenTyVar{-instance Eq-}, - nameTyVar - ) -import Unique ( Unique{-instance Eq-}, Uniquable(..), - integerTyConKey, ratioTyConKey, - mkUnique, incrUnique, - initTidyUniques - ) -import UniqSupply ( UniqSupply, mkSplitUniqSupply, - splitUniqSupply, getUnique - ) -import UniqFM ( UniqFM, lookupUFM, addToUFM ) -import Usage ( SYN_IE(UVar), cloneUVar ) -import Util ( mapAccumL, assertPanic, panic{-ToDo:rm-}, pprTrace, pprPanic ) -import SrcLoc ( noSrcLoc ) -import Constants ( tARGET_MIN_INT, tARGET_MAX_INT ) -import Bag -import Maybes - +import Specialise ( specProgram) +import SpecConstr ( specConstrProgram) +import DmdAnal ( dmdAnalPgm ) +import WorkWrap ( wwTopBinds ) +#ifdef OLD_STRICTNESS +import StrictAnal ( saBinds ) +import CprAnalyse ( cprAnalyse ) +#endif + +import UniqSupply ( UniqSupply, mkSplitUniqSupply, splitUniqSupply ) +import IO ( hPutStr, stderr ) +import Outputable + +import Maybes ( orElse ) +import List ( partition ) \end{code} +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ + \begin{code} -core2core :: [CoreToDo] -- spec of what core-to-core passes to do - -> FAST_STRING -- module name (profiling 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 us local_tycons tycon_specs binds - = -- Do the main business - 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 = tidyCorePgm module_name processed_binds - in - lintCoreBindings "TidyCorePgm" True final_binds >> - - - -- Dump output - dumpIfSet (opt_D_dump_simpl || opt_D_verbose_core2core) - "Core transformations" - (pprCoreBindings pprDumpStyle final_binds) >> - - -- Report statistics - doIfSet opt_D_simplifier_stats - (hPutStr stderr ("\nSimplifier Stats:\n") >> - hPutStr stderr (showSimplCount simpl_stats) >> - hPutStr stderr "\n") >> +core2core :: HscEnv + -> PersistentCompilerState + -> ModGuts + -> IO ModGuts + +core2core hsc_env pcs + mod_impl@(ModGuts { mg_exports = exports, + mg_binds = binds_in, + mg_rules = rules_in }) + = do + let dflags = hsc_dflags hsc_env + hpt = hsc_HPT hsc_env + ghci_mode = hsc_mode hsc_env + core_todos = dopt_CoreToDo dflags + pkg_rule_base = eps_rule_base (pcs_EPS pcs) -- Rule-base accumulated from imported packages + + us <- mkSplitUniqSupply 's' + let (cp_us, ru_us) = splitUniqSupply us + + -- COMPUTE THE RULE BASE TO USE + (rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs) + <- prepareRules dflags pkg_rule_base hpt ru_us binds_in rules_in + + -- PREPARE THE BINDINGS + let binds1 = updateBinders ghci_mode local_rule_ids + rule_rhs_fvs exports binds_in + + -- 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 - return (final_binds, spec_data) - where - init_specdata = initSpecData local_tycons tycon_specs - - -------------- - do_core_pass info@(binds, us, spec_data, simpl_stats) to_do = - 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 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 us2 binds2 spec_data simpl_stats "FBWW" } - - CoreDoFoldrBuildWWAnal - -> _scc_ "CoreDoFoldrBuildWWAnal" - begin_pass "AnalFBWW" >> - case (analFBWW binds) of { binds2 -> - end_pass us2 binds2 spec_data simpl_stats "AnalFBWW" } - - CoreLiberateCase - -> _scc_ "LiberateCase" - begin_pass "LiberateCase" >> - case (liberateCase opt_LiberateCaseThreshold binds) of { binds2 -> - end_pass us2 binds2 spec_data simpl_stats "LiberateCase" } - - CoreDoFloatInwards - -> _scc_ "FloatInwards" - begin_pass "FloatIn" >> - case (floatInwards binds) of { binds2 -> - end_pass us2 binds2 spec_data simpl_stats "FloatIn" } - - CoreDoFullLaziness - -> _scc_ "CoreFloating" - begin_pass "FloatOut" >> - case (floatOutwards us1 binds) of { binds2 -> - end_pass us2 binds2 spec_data simpl_stats "FloatOut" } - - CoreDoStaticArgs - -> _scc_ "CoreStaticArgs" - begin_pass "StaticArgs" >> - case (doStaticArgs binds us1) of { binds2 -> - end_pass 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 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 - doIfSet ((not spec_noerrs) || - (opt_ShowImportSpecs && not (isEmptyBag spec_warn))) - (printErrs - (pprSpecErrs module_name spec_errs spec_warn spec_tyerrs)) - >> - - doIfSet (not spec_noerrs) -- Stop here if specialisation errors occured - (ghcExit 1) >> - - end_pass us2 p spec_data2 simpl_stats "Specialise" - } - - CoreDoPrintCore -- print result of last pass - -> dumpIfSet (not opt_D_verbose_core2core) "Print Core" - (pprCoreBindings pprDumpStyle binds) >> - return (binds, us1, spec_data, simpl_stats) - - ------------------------------------------------- - - begin_pass what - = if opt_D_show_passes - then hPutStr stderr ("*** Core2Core: "++what++"\n") - else return () - - end_pass us2 binds2 - spec_data2@(SpecData spec_done _ _ _ _ _ _ _) - simpl_stats2 what - = -- Report verbosely, if required - dumpIfSet opt_D_verbose_core2core what - (pprCoreBindings pprDumpStyle binds2) >> - - lintCoreBindings what spec_done binds2 >> - - return - (binds2, -- processed binds, possibly run thru CoreLint - us2, -- UniqSupply 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 + -- 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 (mod_impl { mg_binds = processed_binds, mg_rules = orphan_rules}) + + +simplifyExpr :: DynFlags -- includes spec of what core-to-core passes to do + -> CoreExpr + -> IO CoreExpr +-- simplifyExpr is called by the driver to simplify an +-- expression typed in at the interactive prompt +simplifyExpr dflags expr + = do { + ; showPass dflags "Simplify" + + ; us <- mkSplitUniqSupply 's' + + ; let env = emptySimplEnv SimplGently [] emptyVarSet + (expr', _counts) = initSmpl dflags us (simplExprGently env expr) + + ; dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression" + (pprCoreExpr expr') + + ; return expr' + } + + +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 mode switches) + = _scc_ "Simplify" simplifyPgm dfs rb mode switches 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 (dmdAnalPgm 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 CoreDoSpecConstr + = _scc_ "SpecConstr" noStats dfs (specConstrProgram dfs us binds) +#ifdef OLD_STRICTNESS +doCorePass dfs rb us binds CoreDoOldStrictness + = _scc_ "OldStrictness" noStats dfs (doOldStrictness dfs binds) +#endif +doCorePass dfs rb us binds CoreDoPrintCore + = _scc_ "PrintCore" noStats dfs (printCore binds) +doCorePass dfs rb us binds CoreDoGlomBinds + = noStats dfs (glomBinds dfs binds) +doCorePass dfs rb us binds (CoreDoRuleCheck phase pat) + = noStats dfs (ruleCheck dfs phase pat binds) +doCorePass dfs rb us binds CoreDoNothing + = noStats dfs (return binds) + +#ifdef OLD_STRICTNESS +doOldStrictness dfs binds + = do binds1 <- saBinds dfs binds + binds2 <- cprAnalyse dfs binds1 + return binds2 +#endif + +printCore binds = do dumpIfSet True "Print Core" + (pprCoreBindings binds) + return binds + +ruleCheck dflags phase pat binds = do showPass dflags "RuleCheck" + printDump (ruleCheckProgram phase pat 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. - -9. Give all binders a nice print-name. Their uniques aren't changed; rather we give - them lexically unique occ-names, so that we can safely print the OccNae only - in the interface file. [Bad idea to change the uniques, because the code - generator makes global labels from the uniques for local thunks etc.] - - -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 -> [CoreBinding] -> [CoreBinding] - -tidyCorePgm mod binds_in - = initTM mod indirection_env $ - tidyTopBindings (catMaybes reduced_binds) `thenTM` \ binds -> - returnTM (bagToList binds) +prepareRules :: DynFlags -> PackageRuleBase -> HomePackageTable + -> UniqSupply + -> [CoreBind] + -> [IdCoreRule] -- Local rules + -> IO (RuleBase, -- Full rule base + IdSet, -- Local rule Ids + [IdCoreRule], -- Orphan rules + IdSet) -- RHS free vars of all rules + +prepareRules dflags pkg_rule_base hpt us binds local_rules + = do { let env = emptySimplEnv SimplGently [] local_ids + (better_rules,_) = initSmpl dflags us (mapSmpl (simplRule env) local_rules) + + ; let (local_rules, orphan_rules) = partition ((`elemVarSet` local_ids) . fst) better_rules + -- We use (`elemVarSet` local_ids) rather than isLocalId because + -- isLocalId isn't true of class methods. + -- If we miss any rules for Ids defined here, then we end up + -- giving the local decl a new Unique (because the in-scope-set is the + -- same as the rule-id set), and now the binding for the class method + -- doesn't have the same Unique as the one in the Class and the tc-env + -- Example: class Foo a where + -- op :: a -> a + -- {-# RULES "op" op x = x #-} + + rule_rhs_fvs = unionVarSets (map (ruleRhsFreeVars . snd) better_rules) + local_rule_base = extendRuleBaseList emptyRuleBase local_rules + local_rule_ids = ruleBaseIds local_rule_base -- Local Ids with rules attached + imp_rule_base = foldl add_rules pkg_rule_base (moduleEnvElts hpt) + rule_base = extendRuleBaseList imp_rule_base orphan_rules + final_rule_base = addRuleBaseFVs rule_base (ruleBaseFVs local_rule_base) + -- The last step black-lists the free vars of local rules too + + ; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules" + (vcat [text "Local rules", pprRuleBase local_rule_base, + text "", + text "Imported rules", pprRuleBase final_rule_base]) + + ; return (final_rule_base, local_rule_ids, orphan_rules, rule_rhs_fvs) + } where - (indirection_env, reduced_binds) = mapAccumL try_bind nullIdEnv binds_in - - try_bind :: IdEnv CoreBinder -> CoreBinding -> (IdEnv CoreBinder, 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 (ValBinder 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 - -> TopTidyM (Bag CoreBinding) - -> TopTidyM (Bag CoreBinding) - -tidyTopBinding (NonRec bndr rhs) thing_inside - = initNestedTM (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' -> - initNestedTM (mapTM tidyCoreExpr rhss) `thenTM` \ (rhss', floats) -> - thing_inside `thenTM` \ binds_inside -> - returnTM ((floats `snocBag` Rec (binders' `zip` rhss')) `unionBags` binds_inside) + add_rules rule_base mod_info = extendRuleBaseList rule_base (md_rules (hm_details mod_info)) + + -- Boringly, we need to gather the in-scope set. + local_ids = foldr (unionVarSet . mkVarSet . bindersOf) emptyVarSet binds + + +updateBinders :: GhciMode + -> IdSet -- Locally defined ids with their Rules attached + -> IdSet -- Ids free in the RHS of local rules + -> Avails -- What is exported + -> [CoreBind] -> [CoreBind] + -- A horrible function + +-- Update the binders of top-level bindings as follows +-- a) Attach the rules for each locally-defined Id to that Id. +-- b) Set the no-discard flag if either the Id is exported, +-- or it's mentioned in the RHS of a rule +-- +-- You might wonder why exported Ids aren't already marked as such; +-- it's just because the type checker is rather busy already and +-- I didn't want to pass in yet another mapping. +-- +-- Reason for (a) +-- - It 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 +-- +-- Reason for (b) +-- It 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. + +updateBinders ghci_mode rule_ids rule_rhs_fvs exports binds + = map update_bndrs binds where - (binders, rhss) = unzip pairs -\end{code} + update_bndrs (NonRec b r) = NonRec (update_bndr b) r + update_bndrs (Rec prs) = Rec [(update_bndr b, r) | (b,r) <- prs] + update_bndr bndr + | dont_discard bndr = setIdLocalExported bndr_with_rules + | otherwise = bndr_with_rules + where + bndr_with_rules = lookupVarSet rule_ids bndr `orElse` bndr + dont_discard bndr = is_exported (idName bndr) + || bndr `elemVarSet` rule_rhs_fvs -Expressions -~~~~~~~~~~~ -\begin{code} -tidyCoreExpr (Var v) = lookupId 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) - = tidyPrimOp prim `thenTM` \ prim' -> - mapTM tidyCoreArg args `thenTM` \ args' -> - returnTM (Prim prim' args') - -tidyCoreExpr (Lam (ValBinder v) body) - = newId v $ \ v' -> - tidyCoreExpr body `thenTM` \ body' -> - returnTM (Lam (ValBinder v') body') - -tidyCoreExpr (Lam (TyBinder tv) body) - = newTyVar tv $ \ tv' -> - tidyCoreExpr body `thenTM` \ body' -> - returnTM (Lam (TyBinder tv') body') - -tidyCoreExpr (Lam (UsageBinder uv) body) - = newUVar uv $ \ uv' -> - tidyCoreExpr body `thenTM` \ body' -> - returnTM (Lam (UsageBinder uv') 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 (NonRec bndr rhs) body) - = tidyCoreExpr rhs `thenTM` \ rhs' -> - newId bndr $ \ bndr' -> - tidyCoreExprEta body `thenTM` \ body' -> - returnTM (Let (NonRec bndr' rhs') body') - -tidyCoreExpr (Let (Rec pairs) body) - = newIds bndrs $ \ bndrs' -> - mapTM tidyCoreExpr rhss `thenTM` \ rhss' -> - tidyCoreExprEta body `thenTM` \ body' -> - returnTM (Let (Rec (bndrs' `zip` rhss')) body') - where - (bndrs, rhss) = unzip pairs - -tidyCoreExpr (SCC cc body) - = tidyCoreExprEta body `thenTM` \ body' -> - returnTM (SCC cc body') - -tidyCoreExpr (Coerce coercion ty body) - = tidyCoreExprEta body `thenTM` \ body' -> - tidyTy ty `thenTM` \ ty' -> - 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' -> - newId binder $ \ binder' -> - 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 -> lookupId v `thenTM` \ 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) = newIds bndrs $ \ bndrs' -> - 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... } + -- In interactive mode, we don't want to discard any top-level + -- entities at all (eg. do not inline them away during + -- simplification), and retain them all in the TypeEnv so they are + -- available from the command line. -- - -- 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) - = newId bndr $ \ bndr' -> - extend_env (tidyCoreExprEta rhs) `thenTM` \ rhs' -> - returnTM (BindDefault bndr' rhs') - where - extend_env = case scrut of - Var v -> extendEnvTM bndr v - other -> \x -> x + -- isExternalName separates the user-defined top-level names from those + -- introduced by the type checker. + is_exported :: Name -> Bool + is_exported | ghci_mode == Interactive = isExternalName + | otherwise = (`elemNameSet` export_fvs) -tidyCoreExprEta e = tidyCoreExpr e `thenTM` \ e' -> - returnTM (etaCoreExpr e') + export_fvs = availsToNameSet exports \end{code} -Arguments -~~~~~~~~~ + +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. + \begin{code} -tidyCoreArg :: CoreArg -> NestTidyM CoreArg - -tidyCoreArg (VarArg v) - = lookupId 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) = tidyTy ty `thenTM` \ ty' -> - returnTM (TyArg ty') -tidyCoreArg (UsageArg u) = returnTM (UsageArg u) +simplRule env rule@(id, BuiltinRule _ _) + = returnSmpl rule +simplRule env rule@(id, Rule act name bndrs args rhs) + = simplBinders env bndrs `thenSmpl` \ (env, bndrs') -> + mapSmpl (simplExprGently env) args `thenSmpl` \ args' -> + simplExprGently env rhs `thenSmpl` \ rhs' -> + returnSmpl (id, Rule act name bndrs' args' rhs') + +-- It's important that simplExprGently does eta reduction. +-- For example, in a rule like: +-- augment g (build h) +-- we do not want to get +-- augment (\a. g a) (build h) +-- otherwise we don't match when given an argument like +-- (\a. h a a) +-- +-- The simplifier does indeed do eta reduction (it's in +-- Simplify.completeLam) but only if -O is on. \end{code} \begin{code} -tidyPrimOp (CCallOp fn casm gc tys ty) - = mapTM tidyTy tys `thenTM` \ tys' -> - tidyTy ty `thenTM` \ ty' -> - returnTM (CCallOp fn casm gc tys' ty') - -tidyPrimOp other_prim_op = returnTM other_prim_op -\end{code} +simplExprGently :: SimplEnv -> CoreExpr -> SimplM CoreExpr +-- Simplifies an expression +-- does occurrence analysis, then simplification +-- and repeats (twice currently) because one pass +-- alone leaves tons of crud. +-- Used (a) for user expressions typed in at the interactive prompt +-- (b) the LHS and RHS of a RULE +-- +-- The name 'Gently' suggests that the SimplifierMode is SimplGently, +-- and in fact that is so.... but the 'Gently' in simplExprGently doesn't +-- enforce that; it just simplifies the expression twice + +simplExprGently env expr + = simplExpr env (occurAnalyseGlobalExpr expr) `thenSmpl` \ expr1 -> + simplExpr env (occurAnalyseGlobalExpr expr1) +\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 -> NestTidyM (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(isIntegerTy i_ty && uniqueOf tycon == ratioTyConKey) - (con, i_ty) - - _ -> (panic "ratio_data_con", panic "integer_ty") - -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 state = Module - -> UniqFM CoreBinder -- Maps Ids to Ids, TyVars to TyVars etc - -> state - -> (a, state) - -type TopTidyM a = TidyM a Unique -type NestTidyM a = TidyM a (Unique, -- Global names - Unique, -- Local names - Bag CoreBinding) -- Floats - - -(initialTopTidyUnique, initialNestedTidyUnique) = initTidyUniques - -initTM :: Module -> UniqFM CoreBinder -> TopTidyM a -> a -initTM mod env m - = case m mod env initialTopTidyUnique of - (result, _) -> result - -initNestedTM :: NestTidyM a -> TopTidyM (a, Bag CoreBinding) -initNestedTM m mod env global_us - = case m mod env (global_us, initialNestedTidyUnique, emptyBag) of - (result, (global_us', _, floats)) -> ((result, floats), global_us') - -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} --- 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 -> TopTidyM a) -> TopTidyM a -mungeTopBinder id thing_inside mod env us - = case lookupIdEnv env id of - Just (ValBinder global) -> thing_inside global mod env us -- Already bound - - other -> -- Give it a new print-name unless it's an exported thing - -- setNameVisibility also does the local/global thing - let - (id', us') | isExported id = (id, us) - | otherwise - = (setIdVisibility (Just mod) us id, - incrUnique us) - - new_env = addToUFM env id (ValBinder id') - in - thing_inside id' mod new_env us' - -mungeTopBinders [] k = k [] -mungeTopBinders (b:bs) k = mungeTopBinder b $ \ b' -> - mungeTopBinders bs $ \ bs' -> - k (b' : bs') - -addTopFloat :: Type -> CoreExpr -> NestTidyM Id -addTopFloat lit_ty lit_rhs mod env (gus, lus, floats) - = let - gus' = incrUnique gus - lit_local = mkSysLocal SLIT("lit") gus lit_ty noSrcLoc - lit_id = setIdVisibility (Just mod) gus lit_local - in - (lit_id, (gus', lus, floats `snocBag` NonRec lit_id lit_rhs)) - -lookupId :: Id -> TidyM Id state -lookupId v mod env usf - = case lookupUFM env v of - Nothing -> (v, usf) - Just (ValBinder v') -> (v', usf) - -extendEnvTM :: Id -> Id -> (TidyM a state) -> TidyM a state -extendEnvTM v v' m mod env usf - = m mod (addOneToIdEnv env v (ValBinder v')) usf -\end{code} - - -Making new local binders -~~~~~~~~~~~~~~~~~~~~~~~~ -\begin{code} -newId id thing_inside mod env (gus, local_uniq, floats) - = let - -- Give the Id a fresh print-name, *and* rename its type - local_uniq' = incrUnique local_uniq - rn_id = setIdVisibility Nothing local_uniq id - id' = apply_to_Id (nmbr_ty env local_uniq') rn_id - env' = addToUFM env id (ValBinder id') - in - thing_inside id' mod env' (gus, local_uniq', floats) - -newIds [] thing_inside - = thing_inside [] -newIds (bndr:bndrs) thing_inside - = newId bndr $ \ bndr' -> - newIds bndrs $ \ bndrs' -> - thing_inside (bndr' : bndrs') - - -newTyVar tyvar thing_inside mod env (gus, local_uniq, floats) - = let - local_uniq' = incrUnique local_uniq - tyvar' = nameTyVar tyvar (uniqToOccName local_uniq) - env' = addToUFM env tyvar (TyBinder tyvar') - in - thing_inside tyvar' mod env' (gus, local_uniq', floats) - -newUVar uvar thing_inside mod env (gus, local_uniq, floats) - = let - local_uniq' = incrUnique local_uniq - uvar' = cloneUVar uvar local_uniq - env' = addToUFM env uvar (UsageBinder uvar') - in - thing_inside uvar' mod env' (gus, local_uniq', floats) -\end{code} - -Re-numbering types -~~~~~~~~~~~~~~~~~~ -\begin{code} -tidyTy ty mod env usf@(_, local_uniq, _) - = (nmbr_ty env local_uniq ty, usf) - -- We can use local_uniq as a base for renaming forall'd variables - -- in the type; we don't need to know how many are consumed. - --- This little impedance-matcher calls nmbrType with the right arguments -nmbr_ty env uniq ty - = nmbrType tv_env u_env uniq ty +simplifyPgm :: DynFlags + -> RuleBase + -> SimplifierMode + -> [SimplifierSwitch] + -> UniqSupply + -> [CoreBind] -- Input + -> IO (SimplCount, [CoreBind]) -- New bindings + +simplifyPgm dflags rule_base + mode switches 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" Opt_D_verbose_core2core binds'; + + return (counts_out, binds') + } where - tv_env :: TyVar -> TyVar - tv_env tyvar = case lookupUFM env tyvar of - Just (TyBinder tyvar') -> tyvar' - other -> tyvar - - u_env :: UVar -> UVar - u_env uvar = case lookupUFM env uvar of - Just (UsageBinder uvar') -> uvar' - other -> uvar + phase_info = case mode of + SimplGently -> "gentle" + SimplPhase n -> show n + + imported_rule_ids = ruleBaseIds rule_base + simpl_env = emptySimplEnv mode switches imported_rule_ids + sw_chkr = getSwitchChecker simpl_env + max_iterations = intSwitchSet sw_chkr MaxSimplifierIterations `orElse` 2 + + 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 us1 (simplTopBinds simpl_env 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' ; + herald = "Simplifier phase " ++ phase_info ++ + ", iteration " ++ show iteration_no ++ + " out of " ++ show max_iterations + } ; + + -- 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 herald + (pprSimplCount counts') ; + + endPass dflags herald Opt_D_dump_simpl_iterations binds' ; + + -- 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} - -