X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=7b9ae306d82ffea3a5d2906ca98a7c5da9d41ef8;hb=f23ba2b294429ccbdeb80f0344ec08f6abf61bb7;hp=2ada37315e570b49f2120efe3f038f70d280dac8;hpb=0596517a9b4b2b32e5d375a986351102ac4540fc;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index 2ada373..7b9ae30 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -1,579 +1,421 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995 +% (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" -module SimplCore ( - core2core - ) where - -import Type ( getTyConDataCons ) ---SAVE:import ArityAnal ( arityAnalProgram ) -import Bag -import BinderInfo ( BinderInfo) -- instances only -import CgCompInfo ( uNFOLDING_CREATION_THRESHOLD, - uNFOLDING_USE_THRESHOLD, - uNFOLDING_OVERRIDE_THRESHOLD, - uNFOLDING_CON_DISCOUNT_WEIGHT +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SwitchResult(..), intSwitchSet, + opt_UsageSPOn, + DynFlags, DynFlag(..), dopt, dopt_CoreToDo ) -import CmdLineOpts -import CoreLint ( lintCoreBindings ) +import CoreLint ( showPass, endPass ) +import CoreSyn +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 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 Id ( getIdUnfolding, - idType, toplevelishId, - idWantsToBeINLINEd, - unfoldingUnfriendlyId, isWrapperId, - mkTemplateLocals - ) -import IdInfo +import Id ( Id, isDataConWrapId, setIdNoDiscard ) +import VarSet import LiberateCase ( liberateCase ) -import MainMonad -import Maybes import SAT ( doStaticArgs ) -import SCCauto ---ANDY: ---import SimplHaskell ( coreToHaskell ) -import SimplMonad ( zeroSimplCount, showSimplCount, TickType, SimplCount ) -import SimplPgm ( simplifyPgm ) -import SimplVar ( leastItCouldCost ) -import Specialise -import SpecUtils ( pprSpecErrs ) -import StrictAnal ( saWwTopBinds ) -import FoldrBuildWW -import AnalFBWW -#if ! OMIT_DEFORESTER -import Deforest ( deforestProgram ) -import DefUtils ( deforestable ) -#endif -import UniqSupply -import Util +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 - -> (GlobalSwitch->SwitchResult)-- "global" command-line info lookup fn - -> 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... - -> MainIO - ([CoreBinding], -- results: program, plus... - IdEnv UnfoldingDetails, -- unfoldings to be exported from here - SpecialiseData) -- specialisation data - -core2core core_todos sw_chkr module_name ppr_style us local_tycons tycon_specs binds - = BSCC("Core2Core") - if null core_todos then -- very rare, I suspect... - -- well, we still must do some renumbering - returnMn ( - (snd (instCoreBindings (mkUniqueSupplyGrimily us) binds), nullIdEnv, init_specdata) - ) - else - (if do_verbose_core2core then - writeMn stderr "VERBOSE CORE-TO-CORE:\n" - else returnMn ()) `thenMn_` - - -- better do the main business - foldl_mn do_core_pass - (binds, us, nullIdEnv, init_specdata, zeroSimplCount) - core_todos - `thenMn` \ (processed_binds, _, inline_env, spec_data, simpl_stats) -> - - (if switch_is_on D_simplifier_stats - then writeMn stderr ("\nSimplifier Stats:\n") - `thenMn_` - writeMn stderr (showSimplCount simpl_stats) - `thenMn_` - writeMn stderr "\n" - else returnMn () - ) `thenMn_` - - returnMn (processed_binds, inline_env, spec_data) - ESCC - where - init_specdata = initSpecData local_tycons tycon_specs - - switch_is_on = switchIsOn sw_chkr - - do_verbose_core2core = switch_is_on D_verbose_core2core - - lib_case_threshold -- ToDo: HACK HACK HACK : FIX ME FIX ME FIX ME - -- Use 4x a known threshold - = case (intSwitchSet sw_chkr UnfoldingOverrideThreshold) of - Nothing -> 4 * uNFOLDING_USE_THRESHOLD - Just xx -> 4 * xx - - ------------- - core_linter = if switch_is_on DoCoreLinting - then lintCoreBindings ppr_style - else ( \ whodunnit spec_done binds -> binds ) - - -------------- - do_core_pass info@(binds, us, inline_env, spec_data, simpl_stats) to_do - = let - (us1, us2) = splitUniqSupply us - in - case to_do of - CoreDoSimplify simpl_sw_chkr - -> BSCC("CoreSimplify") - begin_pass ("Simplify" ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild - then " (foldr/build)" else "") `thenMn_` - case (simplifyPgm binds sw_chkr simpl_sw_chkr simpl_stats us1) of - (p, it_cnt, simpl_stats2) - -> end_pass False us2 p inline_env spec_data simpl_stats2 - ("Simplify (" ++ show it_cnt ++ ")" - ++ if switchIsOn simpl_sw_chkr SimplDoFoldrBuild - then " foldr/build" else "") - ESCC - - CoreDoFoldrBuildWorkerWrapper - -> BSCC("CoreDoFoldrBuildWorkerWrapper") - begin_pass "FBWW" `thenMn_` - case (mkFoldrBuildWW switch_is_on us1 binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "FBWW" - } ESCC - - CoreDoFoldrBuildWWAnal - -> BSCC("CoreDoFoldrBuildWWAnal") - begin_pass "AnalFBWW" `thenMn_` - case (analFBWW switch_is_on binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "AnalFBWW" - } ESCC - - CoreLiberateCase - -> BSCC("LiberateCase") - begin_pass "LiberateCase" `thenMn_` - case (liberateCase lib_case_threshold binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "LiberateCase" - } ESCC - - CoreDoCalcInlinings1 -- avoid inlinings w/ cost-centres - -> BSCC("CoreInlinings1") - begin_pass "CalcInlinings" `thenMn_` - case (calcInlinings False sw_chkr inline_env binds) of { inline_env2 -> - end_pass False us2 binds inline_env2 spec_data simpl_stats "CalcInlinings" - } ESCC - - CoreDoCalcInlinings2 -- allow inlinings w/ cost-centres - -> BSCC("CoreInlinings2") - begin_pass "CalcInlinings" `thenMn_` - case (calcInlinings True sw_chkr inline_env binds) of { inline_env2 -> - end_pass False us2 binds inline_env2 spec_data simpl_stats "CalcInlinings" - } ESCC - - CoreDoFloatInwards - -> BSCC("FloatInwards") - begin_pass "FloatIn" `thenMn_` - case (floatInwards binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "FloatIn" - } ESCC - - CoreDoFullLaziness - -> BSCC("CoreFloating") - begin_pass "FloatOut" `thenMn_` - case (floatOutwards switch_is_on us1 binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "FloatOut" - } ESCC - - CoreDoStaticArgs - -> BSCC("CoreStaticArgs") - begin_pass "StaticArgs" `thenMn_` - case (doStaticArgs binds us1) of { binds2 -> - end_pass False us2 binds2 inline_env 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]) - } ESCC - - CoreDoStrictness - -> BSCC("CoreStranal") - begin_pass "StrAnal" `thenMn_` - case (saWwTopBinds us1 switch_is_on binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "StrAnal" - } ESCC - - CoreDoSpecialising - -> BSCC("Specialise") - begin_pass "Specialise" `thenMn_` - case (specProgram switch_is_on 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 || - (switch_is_on ShowImportSpecs && not (isEmptyBag spec_warn)) then - writeMn stderr (ppShow 1000 {-pprCols-} - (pprSpecErrs module_name spec_errs spec_warn spec_tyerrs)) - `thenMn_` writeMn stderr "\n" - else - returnMn ()) `thenMn_` - - (if not spec_noerrs then -- Stop here if specialisation errors occured - exitMn 1 - else - returnMn ()) `thenMn_` - - end_pass False us2 p inline_env spec_data2 simpl_stats "Specialise" - } - ESCC - - CoreDoDeforest -#if OMIT_DEFORESTER - -> error "ERROR: CoreDoDeforest: not built into compiler\n" -#else - -> BSCC("Deforestation") - begin_pass "Deforestation" `thenMn_` - case (deforestProgram sw_chkr binds us1) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "Deforestation" - } - ESCC -#endif +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ - CoreDoAutoCostCentres - -> BSCC("AutoSCCs") - begin_pass "AutoSCCs" `thenMn_` - case (addAutoCostCentres sw_chkr module_name binds) of { binds2 -> - end_pass False us2 binds2 inline_env spec_data simpl_stats "AutoSCCs" - } - ESCC - - CoreDoPrintCore -- print result of last pass - -> end_pass True us2 binds inline_env spec_data simpl_stats "Print" - - - ------------------------------------------------- - - begin_pass - = if switch_is_on D_show_passes - then \ what -> writeMn stderr ("*** Core2Core: "++what++"\n") - else \ what -> returnMn () - - end_pass print us2 binds2 inline_env2 - spec_data2@(SpecData spec_done _ _ _ _ _ _ _) - simpl_stats2 what - = -- report verbosely, if required - (if (do_verbose_core2core && not print) || - (print && not do_verbose_core2core) - then - writeMn stderr ("\n*** "++what++":\n") - `thenMn_` - writeMn stderr (ppShow 1000 - (ppAboves (map (pprPlainCoreBinding ppr_style) binds2))) - `thenMn_` - writeMn stderr "\n" - else - returnMn ()) `thenMn_` - let - linted_binds = core_linter what spec_done binds2 - in - returnMn - (linted_binds, -- processed binds, possibly run thru CoreLint - us2, -- UniqueSupply for the next guy - inline_env2, -- possibly-updated inline env - spec_data2, -- possibly-updated specialisation info - simpl_stats2 -- accumulated simplifier stats - ) - --- here so it can be inlined... -foldl_mn f z [] = returnMn z -foldl_mn f z (x:xs) = f z x `thenMn` \ 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} ---- ToDo: maybe move elsewhere --- -For top-level, exported binders that either (a)~have been INLINEd by -the programmer or (b)~are sufficiently ``simple'' that they should be -inlined, we want to record this info in a suitable IdEnv. -But: if something has a ``wrapper unfolding,'' we do NOT automatically -give it a regular unfolding (exception below). We usually assume its -worker will get a ``regular'' unfolding. We can then treat these two -levels of unfolding separately (we tend to be very friendly towards -wrapper unfoldings, for example), giving more fine-tuned control. +%************************************************************************ +%* * +\subsection{Dealing with rules} +%* * +%************************************************************************ -The exception is: If the ``regular unfolding'' mentions no other -global Ids (i.e., it's all PrimOps and cases and local Ids) then we -assume it must be really good and we take it anyway. +-- 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. -We also need to check that everything in the RHS (values and types) -will be visible on the other side of an interface, too. +-- 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} -calcInlinings :: Bool -- True => inlinings with _scc_s are OK - -> (GlobalSwitch -> SwitchResult) - -> IdEnv UnfoldingDetails - -> [CoreBinding] - -> IdEnv UnfoldingDetails - -calcInlinings scc_s_OK sw_chkr inline_env_so_far top_binds - = let - result = foldl calci inline_env_so_far top_binds - in - --pprTrace "inline env:\n" (ppAboves (map pp_item (getIdEnvMapping result))) - result +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 - pp_item (binder, details) - = ppCat [ppr PprDebug binder, ppStr "=>", pp_det details] - where - pp_det NoUnfoldingDetails = ppStr "_N_" - pp_det (IWantToBeINLINEd _) = ppStr "INLINE" - pp_det (GenForm _ _ expr guide) - = ppAbove (ppr PprDebug guide) (ppr PprDebug expr) - pp_det other = ppStr "???" - - ------------ - switch_is_on = switchIsOn sw_chkr - - my_trace = if (switch_is_on ReportWhyUnfoldingsDisallowed) - then trace - else \ msg stuff -> stuff - - (unfolding_creation_threshold, explicit_creation_threshold) - = case (intSwitchSet sw_chkr UnfoldingCreationThreshold) of - Nothing -> (uNFOLDING_CREATION_THRESHOLD, False) - Just xx -> (xx, True) - - unfold_use_threshold - = case (intSwitchSet sw_chkr UnfoldingUseThreshold) of - Nothing -> uNFOLDING_USE_THRESHOLD - Just xx -> xx - - unfold_override_threshold - = case (intSwitchSet sw_chkr UnfoldingOverrideThreshold) of - Nothing -> uNFOLDING_OVERRIDE_THRESHOLD - Just xx -> xx - - con_discount_weight = uNFOLDING_CON_DISCOUNT_WEIGHT - - calci inline_env (Rec pairs) - = foldl (calc True{-recursive-}) inline_env pairs - - calci inline_env bind@(NonRec binder rhs) - = calc False{-not recursive-} inline_env (binder, rhs) - - --------------------------------------- - - calc is_recursive inline_env (binder, rhs) - | not (toplevelishId binder) - = --pprTrace "giving up on not top-level:" (ppr PprDebug binder) - ignominious_defeat - - | rhs_mentions_an_unmentionable - || (not explicit_INLINE_requested - && (rhs_looks_like_a_caf || guidance_says_don't || guidance_size_too_big)) - = let - my_my_trace - = if explicit_INLINE_requested - && not (isWrapperId binder) -- these always claim to be INLINEd - && not have_inlining_already - then trace -- we'd better have a look... - else my_trace - - which = if scc_s_OK then " (late):" else " (early):" - in - --pprTrace "giving up on size:" (ppCat [ppr PprDebug binder, ppr PprDebug - -- [rhs_mentions_an_unmentionable, explicit_INLINE_requested, - -- rhs_looks_like_a_caf, guidance_says_don't, guidance_size_too_big]]) ( - my_my_trace ("unfolding disallowed for"++which++(ppShow 80 (ppr PprDebug binder))) ( - ignominious_defeat - ) - --) - - | rhs `isWrapperFor` binder - -- Don't add an explicit "unfolding"; let the worker/wrapper - -- stuff do its thing. INLINE things don't get w/w'd, so - -- they will be OK. - = --pprTrace "giving up on isWrapperFor:" (ppr PprDebug binder) - ignominious_defeat - -#if ! OMIT_DEFORESTER - -- For the deforester: bypass the barbed wire for recursive - -- functions that want to be inlined and are tagged deforestable - -- by the user, allowing these things to be communicated - -- across module boundaries. - - | is_recursive && - explicit_INLINE_requested && - deforestable binder && - scc_s_OK -- hack, only get them in - -- calc_inlinings2 - = glorious_success UnfoldAlways -#endif + 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 + -- rule_fvs is the set of all variables mentioned in this module's rules + rule_fvs = unionVarSets [ ruleSomeFreeVars isId rule | (_,rule) <- local_rules ] - | is_recursive && not rhs_looks_like_a_data_val - -- The only recursive defns we are prepared to tolerate at the - -- moment is top-level very-obviously-a-data-value ones. - -- We *need* these for dictionaries to be exported! - = --pprTrace "giving up on rec:" (ppr PprDebug binder) - ignominious_defeat + rule_base = extendRuleBaseList emptyRuleBase local_rules + rule_lhs_fvs = ruleBaseFVs rule_base + rule_ids = ruleBaseIds rule_base - -- Not really interested unless it's exported, but doing it - -- this way (not worrying about export-ness) gets us all the - -- workers/specs, etc., too; which we will need for generating - -- interfaces. We are also not interested if this binder is - -- in the environment we already have (perhaps from a previous - -- run of calcInlinings -- "earlier" is presumed to mean - -- "better"). + zap_bind (NonRec b r) = NonRec (zap_bndr b) r + zap_bind (Rec prs) = Rec [(zap_bndr b, r) | (b,r) <- prs] - | explicit_INLINE_requested - = glorious_success UnfoldAlways + zap_bndr bndr = case lookupVarSet rule_ids bndr of + Just bndr' -> setIdNoDiscard bndr' + Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr + | otherwise -> bndr +\end{code} - | otherwise - = glorious_success guidance - where - guidance - = calcUnfoldingGuidance scc_s_OK max_out_threshold rhs - where - max_out_threshold = if explicit_INLINE_requested - then 100000 -- you asked for it, you got it - else unfolding_creation_threshold - - guidance_size - = case guidance of - UnfoldAlways -> 0 -- *extremely* small - EssentialUnfolding -> 0 -- ditto - UnfoldIfGoodArgs _ _ _ size -> size - - guidance_says_don't = case guidance of { UnfoldNever -> True; _ -> False } - - guidance_size_too_big - -- Does the guidance suggest that this unfolding will - -- be of no use *no matter* the arguments given to it? - -- Could be more sophisticated... - = case guidance of - UnfoldAlways -> False - EssentialUnfolding -> False - UnfoldIfGoodArgs _ no_val_args arg_info_vec size - - -> if explicit_creation_threshold then - False -- user set threshold; don't second-guess... - - else if no_val_args == 0 && rhs_looks_like_a_data_val then - False -- we'd like a top-level data constr to be - -- visible even if it is never unfolded - else - let - cost - = leastItCouldCost con_discount_weight size no_val_args - arg_info_vec rhs_arg_tys - in --- (if (unfold_use_threshold < cost) then (pprTrace "cost:" (ppInt cost)) else \x->x ) ( - unfold_use_threshold < cost --- ) - - - rhs_looks_like_a_caf = not (manifestlyWHNF rhs) - - rhs_looks_like_a_data_val - = case (collectBinders rhs) of - (_, _, [], Con _ _ _) -> True - other -> False - - rhs_arg_tys - = case (collectBinders rhs) of - (_, _, val_binders, _) -> map idType val_binders - - (mentioned_ids, _, _, mentions_litlit) - = mentionedInUnfolding (\x -> x) rhs - - rhs_mentions_an_unmentionable - = --pprTrace "mentions:" (ppCat [ppr PprDebug binder, ppr PprDebug [(i,unfoldingUnfriendlyId i) | i <- mentioned_ids ]]) ( - any unfoldingUnfriendlyId mentioned_ids - || mentions_litlit - --) - -- ToDo: probably need to chk tycons/classes... - - mentions_no_other_ids = null mentioned_ids - - explicit_INLINE_requested - -- did it come from a user {-# INLINE ... #-}? - -- (Warning: must avoid including wrappers.) - = idWantsToBeINLINEd binder - && not (rhs `isWrapperFor` binder) - - have_inlining_already = maybeToBool (lookupIdEnv inline_env binder) - - ignominious_defeat = inline_env -- just give back what we got - - {- - "glorious_success" is ours if we've found a suitable unfolding. - - But we check for a couple of fine points. - - (1) If this Id already has an inlining in the inline_env, - we don't automatically take it -- the earlier one is - "likely" to be better. - - But if the new one doesn't mention any other global - Ids, and it's pretty small (< UnfoldingOverrideThreshold), - then we take the chance that the new one *is* better. - - (2) If we have an Id w/ a worker/wrapper split (with - an unfolding for the wrapper), we tend to want to keep - it -- and *nuke* any inlining that we conjured up - earlier. - - But, again, if this unfolding doesn't mention any - other global Ids (and small enough), then it is - probably better than the worker/wrappery, so we take - it. - -} - glorious_success guidance - = let - new_env = addOneToIdEnv inline_env binder (mkUnfolding guidance rhs) - - foldr_building = switch_is_on FoldrBuildOn - in - if (not have_inlining_already) then - -- Not in env: we take it no matter what - -- NB: we could check for worker/wrapper-ness, - -- but the truth is we probably haven't run - -- the strictness analyser yet. - new_env - - else if explicit_INLINE_requested then - -- If it was a user INLINE, then we know it's already - -- in the inline_env; we stick with what we already - -- have. - --pprTrace "giving up on INLINE:" (ppr PprDebug binder) - ignominious_defeat - - else if isWrapperId binder then - -- It's in the env, but we have since worker-wrapperised; - -- we either take this new one (because it's so good), - -- or we *undo* the one in the inline_env, so the - -- wrapper-inlining will take over. - - if mentions_no_other_ids {- *** && size <= unfold_override_threshold -} then - new_env - else - delOneFromIdEnv inline_env binder - - else - -- It's in the env, nothing to do w/ worker wrapper; - -- we'll take it if it is better. - - if not foldr_building -- ANDY hates us... (see below) - && mentions_no_other_ids - && guidance_size <= unfold_override_threshold then - new_env - else - --pprTrace "giving up on final hurdle:" (ppCat [ppr PprDebug binder, ppInt guidance_size, ppInt unfold_override_threshold]) - ignominious_defeat -- and at the last hurdle, too! +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} +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{Glomming} +%* * +%************************************************************************ + +\begin{code} +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} -ANDY, on the hatred of the check above; why obliterate it? Consider - head xs = foldr (\ x _ -> x) (_|_) xs +%************************************************************************ +%* * +\subsection{The driver for the simplifier} +%* * +%************************************************************************ -This then is exported via a pragma. However, -*if* you include the extra code above, you will -export the non-foldr/build version. +\begin{code} +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 + 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}