X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplCore.lhs;h=8b2118a443439b3e467f52118c23429fe897d813;hb=36d22a1cb608e8572776ab6d402fd0c1a9287dc5;hp=e3447f04bdaa9f15f370ed99fbf7829c092b0637;hpb=a20c26e871de939c9708892839787404420554ca;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplCore.lhs b/ghc/compiler/simplCore/SimplCore.lhs index e3447f0..8b2118a 100644 --- a/ghc/compiler/simplCore/SimplCore.lhs +++ b/ghc/compiler/simplCore/SimplCore.lhs @@ -4,119 +4,59 @@ \section[SimplCore]{Driver for simplifying @Core@ programs} \begin{code} -module SimplCore ( core2core ) where +module SimplCore ( core2core, simplifyExpr ) where #include "HsVersions.h" -import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), - SwitchResult, switchIsOn, - opt_D_dump_occur_anal, - opt_D_dump_simpl_iterations, - opt_D_simplifier_stats, - opt_D_dump_simpl, - opt_D_verbose_core2core, - opt_D_dump_occur_anal +import CmdLineOpts ( CoreToDo(..), SimplifierSwitch(..), + SimplifierMode(..), DynFlags, DynFlag(..), dopt, + dopt_CoreToDo, buildCoreToDo ) -import CoreLint ( beginPass, endPass ) import CoreSyn -import PprCore ( pprCoreBindings ) -import OccurAnal ( occurAnalyseBinds ) -import CoreUtils ( exprIsTrivial, coreExprType ) -import Simplify ( simplBind ) -import SimplUtils ( etaCoreExpr, findDefault ) +import TcIface ( loadImportedRules ) +import HscTypes ( HscEnv(..), ModGuts(..), ExternalPackageState(..), + Dependencies( dep_mods ), + hscEPS, hptRules ) +import CSE ( cseProgram ) +import Rules ( RuleBase, ruleBaseIds, emptyRuleBase, + extendRuleBaseList, pprRuleBase, ruleCheckProgram ) +import PprCore ( pprCoreBindings, pprCoreExpr, pprIdRules ) +import OccurAnal ( occurAnalysePgm, occurAnalyseGlobalExpr ) +import IdInfo ( setNewStrictnessInfo, newStrictnessInfo, + setWorkerInfo, workerInfo, + setSpecInfo, specInfo ) +import CoreUtils ( coreBindsSize ) +import Simplify ( simplTopBinds, simplExpr ) +import SimplEnv ( SimplEnv, simplBinders, mkSimplEnv, setInScopeSet ) import SimplMonad -import CoreUnfold -import Const ( Con(..), Literal(..), literalType, mkMachInt ) -import ErrUtils ( dumpIfSet ) +import ErrUtils ( dumpIfSet, dumpIfSet_dyn, showPass ) +import CoreLint ( endPass ) +import VarEnv ( mkInScopeSet ) import FloatIn ( floatInwards ) import FloatOut ( floatOutwards ) -import Id ( Id, mkSysLocal, mkUserId, isBottomingId, - idType, setIdType, idName, idInfo, idDetails - ) -import IdInfo ( InlinePragInfo(..), specInfo, setSpecInfo, - inlinePragInfo, setInlinePragInfo, - setUnfoldingInfo - ) -import VarEnv +import Id ( Id, modifyIdInfo, idInfo, idIsFrom, isExportedId, isLocalId, + idSpecialisation, setIdSpecialisation ) +import Rules ( addRules ) import VarSet -import Module ( Module ) -import Name ( mkLocalName, tidyOccName, tidyTopName, initTidyOccEnv, isExported, - NamedThing(..), OccName - ) -import TyCon ( TyCon, isDataTyCon ) -import PrimOp ( PrimOp(..) ) -import PrelInfo ( unpackCStringId, unpackCString2Id, addr2IntegerId ) -import Type ( Type, splitAlgTyConApp_maybe, - isUnLiftedType, - tidyType, tidyTypes, tidyTopType, tidyTyVar, tidyTyVars, - Type - ) -import Class ( Class, classSelIds ) -import TysWiredIn ( smallIntegerDataCon, isIntegerTy ) +import VarEnv import LiberateCase ( liberateCase ) import SAT ( doStaticArgs ) import Specialise ( specProgram) -import SpecEnv ( specEnvToList, specEnvFromList ) -import StrictAnal ( saWwTopBinds ) -import Var ( TyVar, mkId ) -import Unique ( Unique, Uniquable(..), - ratioTyConKey, mkUnique, incrUnique, initTidyUniques - ) -import UniqSupply ( UniqSupply, splitUniqSupply, uniqFromSupply ) -import Constants ( tARGET_MIN_INT, tARGET_MAX_INT ) -import Util ( mapAccumL ) -import SrcLoc ( noSrcLoc ) -import Bag -import Maybes +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 Ratio ( numerator, denominator ) +import List ( partition ) +import Maybes ( orElse ) \end{code} -\begin{code} -core2core :: [CoreToDo] -- Spec of what core-to-core passes to do - -> Module -- Module name (profiling only) - -> [Class] -- Local classes - -> UniqSupply -- A name supply - -> [CoreBind] -- Input - -> IO [CoreBind] -- Result - -core2core core_todos module_name classes us binds - = do - let (us1, us2) = splitUniqSupply us - - -- Do the main business - processed_binds <- doCorePasses us1 binds core_todos - - -- Do the post-simplification business - post_simpl_binds <- doPostSimplification us2 processed_binds - - -- Do the final tidy-up - final_binds <- tidyCorePgm module_name classes post_simpl_binds - - -- Return results - return final_binds - -doCorePasses us binds [] - = return binds - -doCorePasses us binds (to_do : to_dos) - = do - let (us1, us2) = splitUniqSupply us - binds1 <- doCorePass us1 binds to_do - doCorePasses us2 binds1 to_dos - -doCorePass us binds (CoreDoSimplify sw_chkr) = _scc_ "Simplify" simplifyPgm sw_chkr us binds -doCorePass us binds CoreLiberateCase = _scc_ "LiberateCase" liberateCase binds -doCorePass us binds CoreDoFloatInwards = _scc_ "FloatInwards" floatInwards binds -doCorePass us binds CoreDoFullLaziness = _scc_ "CoreFloating" floatOutwards us binds -doCorePass us binds CoreDoStaticArgs = _scc_ "CoreStaticArgs" doStaticArgs us binds -doCorePass us binds CoreDoStrictness = _scc_ "CoreStranal" saWwTopBinds us binds -doCorePass us binds CoreDoSpecialising = _scc_ "Specialise" specProgram us binds -\end{code} - - %************************************************************************ %* * \subsection{The driver for the simplifier} @@ -124,591 +64,645 @@ doCorePass us binds CoreDoSpecialising = _scc_ "Specialise" specProgram %************************************************************************ \begin{code} -simplifyPgm :: (SimplifierSwitch -> SwitchResult) - -> UniqSupply - -> [CoreBind] -- Input - -> IO [CoreBind] -- New bindings +core2core :: HscEnv + -> ModGuts + -> IO ModGuts -simplifyPgm sw_chkr us binds - = do { - beginPass "Simplify"; +core2core hsc_env guts + = do + let dflags = hsc_dflags hsc_env + core_todos + | Just todo <- dopt_CoreToDo dflags = todo + | otherwise = buildCoreToDo dflags - (termination_msg, it_count, counts, binds') <- iteration us 1 zeroSimplCount binds; + us <- mkSplitUniqSupply 's' + let (cp_us, ru_us) = splitUniqSupply us - dumpIfSet opt_D_simplifier_stats "Simplifier statistics" - (vcat [text termination_msg <+> text "after" <+> ppr it_count <+> text "iterations", - text "", - pprSimplCount counts]); + -- COMPUTE THE RULE BASE TO USE + (imp_rule_base, guts') <- prepareRules hsc_env guts ru_us - endPass "Simplify" - (opt_D_verbose_core2core && not opt_D_dump_simpl_iterations) - binds' - } - where - max_iterations = getSimplIntSwitch sw_chkr MaxSimplifierIterations - simpl_switch_is_on = switchIsOn sw_chkr + -- DO THE BUSINESS + (stats, guts'') <- doCorePasses hsc_env cp_us + (zeroSimplCount dflags) + imp_rule_base guts' core_todos - core_iter_dump binds | opt_D_verbose_core2core = pprCoreBindings binds - | otherwise = empty + dumpIfSet_dyn dflags Opt_D_dump_simpl_stats + "Grand total simplifier statistics" + (pprSimplCount stats) - iteration us iteration_no counts binds - = do { - -- Occurrence analysis - let { tagged_binds = _scc_ "OccAnal" occurAnalyseBinds simpl_switch_is_on binds }; - dumpIfSet opt_D_dump_occur_anal "Occurrence analysis" - (pprCoreBindings tagged_binds); + return guts'' - -- Simplify - let { (binds', counts') = initSmpl sw_chkr us1 (simplTopBinds tagged_binds); - all_counts = counts `plusSimplCount` counts' - } ; - -- Stop if nothing happened; don't dump output - if isZeroSimplCount counts' then - return ("Simplifier reached fixed point", iteration_no, all_counts, binds') - else do { +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" - -- Dump the result of this iteration - dumpIfSet opt_D_dump_simpl_iterations - ("Simplifier iteration " ++ show iteration_no - ++ " out of " ++ show max_iterations) - (vcat[pprSimplCount counts', - text "", - core_iter_dump binds']) ; - - -- Stop if we've run out of iterations - if iteration_no == max_iterations then - do { - if max_iterations > 1 then - hPutStr stderr ("NOTE: Simplifier still going after " ++ - show max_iterations ++ - " iterations; bailing out.\n") - else return (); - - return ("Simplifier baled out", iteration_no, all_counts, binds') - } - - -- Else loop - else iteration us2 (iteration_no + 1) all_counts binds' - } } - where - (us1, us2) = splitUniqSupply us + ; us <- mkSplitUniqSupply 's' + ; let (expr', _counts) = initSmpl dflags us $ + simplExprGently gentleSimplEnv expr -simplTopBinds binds = go binds `thenSmpl` \ (binds', _) -> - returnSmpl binds' - where - go [] = returnSmpl ([], ()) - go (bind1 : binds) = simplBind bind1 (go binds) -\end{code} + ; dumpIfSet_dyn dflags Opt_D_dump_simpl "Simplified expression" + (pprCoreExpr expr') + ; return expr' + } -%************************************************************************ -%* * -\subsection{Tidying core} -%* * -%************************************************************************ - -Several tasks are done by @tidyCorePgm@ - -1. Make certain top-level bindings into Globals. The point is that - Global things get externally-visible labels at code generation - time +gentleSimplEnv :: SimplEnv +gentleSimplEnv = mkSimplEnv SimplGently + (isAmongSimpl []) + emptyRuleBase +doCorePasses :: HscEnv + -> UniqSupply -- uniques + -> SimplCount -- simplifier stats + -> RuleBase -- the main rule base + -> ModGuts -- local binds in (with rules attached) + -> [CoreToDo] -- which passes to do + -> IO (SimplCount, ModGuts) -2. 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.] +doCorePasses hsc_env us stats rb guts [] + = return (stats, guts) - -\begin{code} -tidyCorePgm :: Module -> [Class] -> [CoreBind] -> IO [CoreBind] -tidyCorePgm mod local_classes binds_in +doCorePasses hsc_env us stats rb guts (to_do : to_dos) = do - beginPass "Tidy Core" - let (_, binds_out) = mapAccumL (tidyBind (Just mod)) init_tidy_env binds_in - endPass "Tidy Core" (opt_D_dump_simpl || opt_D_verbose_core2core) binds_out + let (us1, us2) = splitUniqSupply us + (stats1, rb1, guts1) <- doCorePass to_do hsc_env us1 rb guts + doCorePasses hsc_env us2 (stats `plusSimplCount` stats1) rb1 guts1 to_dos + +doCorePass (CoreDoSimplify mode sws) = _scc_ "Simplify" simplifyPgm mode sws +doCorePass CoreCSE = _scc_ "CommonSubExpr" trBinds cseProgram +doCorePass CoreLiberateCase = _scc_ "LiberateCase" trBinds liberateCase +doCorePass CoreDoFloatInwards = _scc_ "FloatInwards" trBinds floatInwards +doCorePass (CoreDoFloatOutwards f) = _scc_ "FloatOutwards" trBindsU (floatOutwards f) +doCorePass CoreDoStaticArgs = _scc_ "StaticArgs" trBinds doStaticArgs +doCorePass CoreDoStrictness = _scc_ "Stranal" trBinds dmdAnalPgm +doCorePass CoreDoWorkerWrapper = _scc_ "WorkWrap" trBindsU wwTopBinds +doCorePass CoreDoSpecialising = _scc_ "Specialise" trBindsU specProgram +doCorePass CoreDoSpecConstr = _scc_ "SpecConstr" trBindsU specConstrProgram +doCorePass CoreDoGlomBinds = trBinds glomBinds +doCorePass CoreDoPrintCore = observe printCore +doCorePass (CoreDoRuleCheck phase pat) = observe (ruleCheck phase pat) +doCorePass CoreDoNothing = observe (\ _ _ -> return ()) +#ifdef OLD_STRICTNESS +doCorePass CoreDoOldStrictness = _scc_ "OldStrictness" trBinds doOldStrictness +#endif + +#ifdef OLD_STRICTNESS +doOldStrictness dfs binds + = do binds1 <- saBinds dfs binds + binds2 <- cprAnalyse dfs binds1 + return binds2 +#endif + +printCore _ binds = dumpIfSet True "Print Core" (pprCoreBindings binds) + +ruleCheck phase pat dflags binds = do showPass dflags "RuleCheck" + printDump (ruleCheckProgram phase pat binds) + +-- Most passes return no stats and don't change rules +trBinds :: (DynFlags -> [CoreBind] -> IO [CoreBind]) + -> HscEnv -> UniqSupply -> RuleBase -> ModGuts + -> IO (SimplCount, RuleBase, ModGuts) +trBinds do_pass hsc_env us rb guts + = do { binds' <- do_pass dflags (mg_binds guts) + ; return (zeroSimplCount dflags, rb, guts { mg_binds = binds' }) } where - -- Make sure to avoid the names of class operations - -- They don't have top-level bindings, so we won't see them - -- in binds_in; so we must initialise the tidy_env appropriately - -- - -- We also make sure to avoid any exported binders. Consider - -- f{-u1-} = 1 -- Local decl - -- ... - -- f{-u2-} = 2 -- Exported decl - -- - -- The second exported decl must 'get' the name 'f', so we - -- have to put 'f' in the avoids list before we get to the first - -- decl. Name.tidyName then does a no-op on exported binders. - init_tidy_env = (initTidyOccEnv avoids, emptyVarEnv) - avoids = [getOccName sel_id | cls <- local_classes, - sel_id <- classSelIds cls] - ++ - [getOccName bndr | bind <- binds_in, - bndr <- bindersOf bind, - isExported bndr] - -tidyBind :: Maybe Module -- (Just m) for top level, Nothing for nested - -> TidyEnv - -> CoreBind - -> (TidyEnv, CoreBind) -tidyBind maybe_mod env (NonRec bndr rhs) - = let - (env', bndr') = tidyBndr maybe_mod env bndr - rhs' = tidyExpr env rhs - in - (env', NonRec bndr' rhs') - -tidyBind maybe_mod env (Rec pairs) - = let - -- We use env' when tidying the rhss - -- When tidying the binder itself we may tidy it's - -- specialisations; if any of these mention other binders - -- in the group we should really feed env' to them too; - -- but that seems (a) unlikely and (b) a bit tiresome. - -- So I left it out for now - - (bndrs, rhss) = unzip pairs - (env', bndrs') = mapAccumL (tidyBndr maybe_mod) env bndrs - rhss' = map (tidyExpr env') rhss - in - (env', Rec (zip bndrs' rhss')) - -tidyExpr env (Type ty) = Type (tidyType env ty) -tidyExpr env (Con con args) = Con con (map (tidyExpr env) args) -tidyExpr env (App f a) = App (tidyExpr env f) (tidyExpr env a) -tidyExpr env (Note n e) = Note (tidyNote env n) (tidyExpr env e) - -tidyExpr env (Let b e) = Let b' (tidyExpr env' e) - where - (env', b') = tidyBind Nothing env b - -tidyExpr env (Case e b alts) = Case (tidyExpr env e) b' (map (tidyAlt env') alts) - where - (env', b') = tidyNestedBndr env b - -tidyExpr env (Var v) = case lookupVarEnv var_env v of - Just v' -> Var v' - Nothing -> Var v - where - (_, var_env) = env - -tidyExpr env (Lam b e) = Lam b' (tidyExpr env' e) - where - (env', b') = tidyNestedBndr env b - -tidyAlt env (con, vs, rhs) = (con, vs', tidyExpr env' rhs) - where - (env', vs') = mapAccumL tidyNestedBndr env vs - -tidyNote env (Coerce t1 t2) = Coerce (tidyType env t1) (tidyType env t2) - -tidyNote env note = note -\end{code} - -\begin{code} -tidyBndr (Just mod) env id = tidyTopBndr mod env id -tidyBndr Nothing env var = tidyNestedBndr env var - -tidyNestedBndr env tyvar - | isTyVar tyvar - = tidyTyVar env tyvar - -tidyNestedBndr env@(tidy_env, var_env) id - = -- Non-top-level variables - let - -- Give the Id a fresh print-name, *and* rename its type - -- The SrcLoc isn't important now, though we could extract it from the Id - name' = mkLocalName (getUnique id) occ' noSrcLoc - (tidy_env', occ') = tidyOccName tidy_env (getOccName id) - ty' = tidyType env (idType id) - id' = mkUserId name' ty' - -- NB: This throws away the IdInfo of the Id, which we - -- no longer need. That means we don't need to - -- run over it with env, nor renumber it. - var_env' = extendVarEnv var_env id id' - in - ((tidy_env', var_env'), id') - -tidyTopBndr mod env@(tidy_env, var_env) id - = -- Top level variables - let - (tidy_env', name') = tidyTopName mod tidy_env (idName id) - ty' = tidyTopType (idType id) - idinfo' = tidyIdInfo env (idInfo id) - id' = mkId name' ty' (idDetails id) idinfo' - var_env' = extendVarEnv var_env id id' - in - ((tidy_env', var_env'), id') - --- tidyIdInfo does these things: --- a) tidy the specialisation info (if any) --- b) zap a complicated ICanSafelyBeINLINEd pragma, --- c) zap the unfolding --- The latter two are to avoid space leaks - -tidyIdInfo env info - = info3 + dflags = hsc_dflags hsc_env + +trBindsU :: (DynFlags -> UniqSupply -> [CoreBind] -> IO [CoreBind]) + -> HscEnv -> UniqSupply -> RuleBase -> ModGuts + -> IO (SimplCount, RuleBase, ModGuts) +trBindsU do_pass hsc_env us rb guts + = do { binds' <- do_pass dflags us (mg_binds guts) + ; return (zeroSimplCount dflags, rb, guts { mg_binds = binds' }) } + where + dflags = hsc_dflags hsc_env + +-- Observer passes just peek; don't modify the bindings at all +observe :: (DynFlags -> [CoreBind] -> IO a) + -> HscEnv -> UniqSupply -> RuleBase -> ModGuts + -> IO (SimplCount, RuleBase, ModGuts) +observe do_pass hsc_env us rb guts + = do { binds <- do_pass dflags (mg_binds guts) + ; return (zeroSimplCount dflags, rb, guts) } where - spec_items = specEnvToList (specInfo info) - spec_env' = specEnvFromList (map tidy_item spec_items) - info1 | null spec_items = info - | otherwise = spec_env' `setSpecInfo` info - - info2 = case inlinePragInfo info of - ICanSafelyBeINLINEd _ _ -> NoInlinePragInfo `setInlinePragInfo` info1 - other -> info1 - - info3 = noUnfolding `setUnfoldingInfo` info2 - - tidy_item (tyvars, tys, rhs) - = (tyvars', tidyTypes env' tys, tidyExpr env' rhs) - where - (env', tyvars') = tidyTyVars env tyvars + dflags = hsc_dflags hsc_env \end{code} %************************************************************************ %* * -\subsection{PostSimplification} +\subsection{Dealing with rules} %* * %************************************************************************ -Several tasks are performed by the post-simplification pass - -1. Make the representation of NoRep literals explicit, and - float their bindings to the top level. We only do the floating - part for NoRep lits inside a lambda (else no gain). We need to - take care with let x = "foo" in e - that we don't end up with a silly binding - let x = y in e - with a floated "foo". What a bore. - -2. *Mangle* cases involving par# in the discriminant. The unfolding - for par in PrelConc.lhs include case expressions with integer - results solely to fool the strictness analyzer, the simplifier, - and anyone else who might want to fool with the evaluation order. - At this point in the compiler our evaluation order is safe. - Therefore, we convert expressions of the form: - - case par# e of - 0# -> rhs - _ -> parError# - ==> - case par# e of - _ -> rhs - - fork# isn't handled like this - it's an explicit IO operation now. - The reason is that fork# returns a ThreadId#, which gets in the - way of the above scheme. And anyway, IO is the only guaranteed - way to enforce ordering --SDM. - -3. Mangle cases involving seq# in the discriminant. Up to this - point, seq# will appear like this: - - case seq# e of - 0# -> seqError# - _ -> ... - - where the 0# branch is purely to bamboozle the strictness analyser - (see case 4 above). This code comes from an unfolding for 'seq' - in Prelude.hs. We translate this into - - case e of - _ -> ... - - Now that the evaluation order is safe. - -4. Do eta reduction for lambda abstractions appearing in: - - the RHS of case alternatives - - the body of a let - - These will otherwise turn into local bindings during Core->STG; - better to nuke them if possible. (In general the simplifier does - eta expansion not eta reduction, up to this point. It does eta - on the RHSs of bindings but not the RHSs of case alternatives and - let bodies) - - -------------------- NOT DONE ANY MORE ------------------------ -[March 98] Indirections are now elimianted by the occurrence analyser -1. Eliminate indirections. The point here is to transform - x_local = E - x_exported = x_local - ==> - x_exported = E - -[Dec 98] [Not now done because there is no penalty in the code - generator for using the former form] -2. Convert - case x of {...; x' -> ...x'...} - ==> - case x of {...; _ -> ...x... } - See notes in SimplCase.lhs, near simplDefault for the reasoning here. --------------------------------------------------------------- +-- 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. -Special case -~~~~~~~~~~~~ - -NOT ENABLED AT THE MOMENT (because the floated Ids are global-ish -things, and we need local Ids for non-floated stuff): - - Don't float stuff out of a binder that's marked as a bottoming Id. - Reason: it doesn't do any good, and creates more CAFs that increase - the size of SRTs. - -eg. - - f = error "string" - -is translated to - - f' = unpackCString# "string" - f = error f' +\begin{code} +prepareRules :: HscEnv + -> ModGuts + -> UniqSupply + -> IO (RuleBase, -- Rule base for imported things, incl + -- (a) rules defined in this module (orphans) + -- (b) rules from other packages + -- (c) rules from other modules in home package + ModGuts) -- Modified fields are + -- (a) Bindings have rules attached, + -- (b) Rules are now just orphan rules + +prepareRules hsc_env@(HscEnv { hsc_dflags = dflags, hsc_HPT = hpt }) + guts@(ModGuts { mg_binds = binds, mg_deps = deps, mg_rules = local_rules }) + us + = do { eps <- hscEPS hsc_env + + ; let -- Simplify the local rules; boringly, we need to make an in-scope set + -- from the local binders, to avoid warnings from Simplify.simplVar + local_ids = mkInScopeSet (mkVarSet (bindersOfBinds binds)) + env = setInScopeSet gentleSimplEnv local_ids + (better_rules,_) = initSmpl dflags us (mapSmpl (simplRule env) local_rules) + home_pkg_rules = hptRules hsc_env (dep_mods deps) + + (orphan_rules, rules_for_locals) = partition isOrphanRule better_rules + -- Get the rules for locally-defined Ids out of the RuleBase + -- 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 (hackily) the + -- same as the non-local-rule-id set, so the Id looks as if it's in scope + -- and hence should be cloned), 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 #-} + + -- NB: we assume that the imported rules dont include + -- rules for Ids in this module; if there is, the above bad things may happen + + pkg_rule_base = eps_rule_base eps + hpt_rule_base = extendRuleBaseList pkg_rule_base home_pkg_rules + imp_rule_base = extendRuleBaseList hpt_rule_base orphan_rules + + -- Update the binders in the local bindings with the lcoal rules + -- Update the binders of top-level bindings by + -- attaching the rules for each locally-defined Id to that Id. + -- + -- Reason + -- - 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 + -- - The imported rules are carried in the in-scope set + -- which is extended on each iteration by the new wave of + -- local binders; any rules which aren't on the binding will + -- thereby get dropped + local_rule_base = extendRuleBaseList emptyRuleBase rules_for_locals + binds_w_rules = updateBinders local_rule_base binds + + ; dumpIfSet_dyn dflags Opt_D_dump_rules "Transformation rules" + (vcat [text "Local rules", pprIdRules better_rules, + text "", + text "Imported rules", pprRuleBase imp_rule_base]) + +#ifdef DEBUG + ; let bad_rules = filter (idIsFrom (mg_module guts)) + (varSetElems (ruleBaseIds imp_rule_base)) + ; WARN( not (null bad_rules), ppr bad_rules ) return () +#endif + ; return (imp_rule_base, guts { mg_binds = binds_w_rules, mg_rules = orphan_rules }) + } -hence f' and f become CAFs. Instead, the special case for -tidyTopBinding below makes sure this comes out as +updateBinders :: RuleBase -> [CoreBind] -> [CoreBind] +updateBinders rule_base binds + = map update_bndrs binds + where + rule_ids = ruleBaseIds rule_base - f = let f' = unpackCString# "string" in error f' + update_bndrs (NonRec b r) = NonRec (update_bndr b) r + update_bndrs (Rec prs) = Rec [(update_bndr b, r) | (b,r) <- prs] -and we can safely ignore f as a CAF, since it can only ever be entered once. + update_bndr bndr = case lookupVarSet rule_ids bndr of + Nothing -> bndr + Just id -> bndr `setIdSpecialisation` idSpecialisation id +\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. \begin{code} -doPostSimplification :: UniqSupply -> [CoreBind] -> IO [CoreBind] -doPostSimplification us binds_in - = do - beginPass "Post-simplification pass" - let binds_out = initPM us (postSimplTopBinds binds_in) - endPass "Post-simplification pass" opt_D_verbose_core2core binds_out - -postSimplTopBinds :: [CoreBind] -> PostM [CoreBind] -postSimplTopBinds binds - = mapPM postSimplTopBind binds `thenPM` \ binds' -> - returnPM (bagToList (unionManyBags binds')) - -postSimplTopBind :: CoreBind -> PostM (Bag CoreBind) -postSimplTopBind (NonRec bndr rhs) - | isBottomingId bndr -- Don't lift out floats for bottoming Ids - -- See notes above - = getFloatsPM (postSimplExpr rhs) `thenPM` \ (rhs', floats) -> - returnPM (unitBag (NonRec bndr (foldrBag Let rhs' floats))) - -postSimplTopBind bind - = getFloatsPM (postSimplBind bind) `thenPM` \ (bind', floats) -> - returnPM (floats `snocBag` bind') - -postSimplBind (NonRec bndr rhs) - = postSimplExpr rhs `thenPM` \ rhs' -> - returnPM (NonRec bndr rhs') - -postSimplBind (Rec pairs) - = mapPM postSimplExpr rhss `thenPM` \ rhss' -> - returnPM (Rec (bndrs `zip` rhss')) - where - (bndrs, rhss) = unzip pairs +simplRule env rule@(IdCoreRule id _ (BuiltinRule _ _)) + = returnSmpl rule +simplRule env (IdCoreRule id is_orph (Rule act name bndrs args rhs)) + = simplBinders env bndrs `thenSmpl` \ (env, bndrs') -> + mapSmpl (simplExprGently env) args `thenSmpl` \ args' -> + simplExprGently env rhs `thenSmpl` \ rhs' -> + returnSmpl (IdCoreRule id is_orph (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} - -Expressions -~~~~~~~~~~~ \begin{code} -postSimplExpr (Var v) = returnPM (Var v) -postSimplExpr (Type ty) = returnPM (Type ty) - -postSimplExpr (App fun arg) - = postSimplExpr fun `thenPM` \ fun' -> - postSimplExpr arg `thenPM` \ arg' -> - returnPM (App fun' arg') - -postSimplExpr (Con (Literal lit) args) - = ASSERT( null args ) - litToRep lit `thenPM` \ (lit_ty, lit_expr) -> - getInsideLambda `thenPM` \ in_lam -> - if in_lam && not (exprIsTrivial lit_expr) then - -- It must have been a no-rep literal with a - -- non-trivial representation; and we're inside a lambda; - -- so float it to the top - addTopFloat lit_ty lit_expr `thenPM` \ v -> - returnPM (Var v) - else - returnPM lit_expr - -postSimplExpr (Con con args) - = mapPM postSimplExpr args `thenPM` \ args' -> - returnPM (Con con args') - -postSimplExpr (Lam bndr body) - = insideLambda bndr $ - postSimplExpr body `thenPM` \ body' -> - returnPM (Lam bndr body') - -postSimplExpr (Let bind body) - = postSimplBind bind `thenPM` \ bind' -> - postSimplExprEta body `thenPM` \ body' -> - returnPM (Let bind' body') - -postSimplExpr (Note note body) - = postSimplExprEta body `thenPM` \ body' -> - returnPM (Note note body') - --- seq#: see notes above. --- NB: seq# :: forall a. a -> Int# -postSimplExpr (Case scrut@(Con (PrimOp SeqOp) [Type ty, e]) bndr alts) - = postSimplExpr e `thenPM` \ e' -> - let - -- The old binder can't have been used, so we - -- can gaily re-use it (yuk!) - new_bndr = setIdType bndr ty - in - postSimplExprEta default_rhs `thenPM` \ rhs' -> - returnPM (Case e' new_bndr [(DEFAULT,[],rhs')]) - where - (other_alts, maybe_default) = findDefault alts - Just default_rhs = maybe_default - --- par#: see notes above. -postSimplExpr (Case scrut@(Con (PrimOp op) args) bndr alts) - | funnyParallelOp op && maybeToBool maybe_default - = postSimplExpr scrut `thenPM` \ scrut' -> - postSimplExprEta default_rhs `thenPM` \ rhs' -> - returnPM (Case scrut' bndr [(DEFAULT,[],rhs')]) - where - (other_alts, maybe_default) = findDefault alts - Just default_rhs = maybe_default +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} -postSimplExpr (Case scrut case_bndr alts) - = postSimplExpr scrut `thenPM` \ scrut' -> - mapPM ps_alt alts `thenPM` \ alts' -> - returnPM (Case scrut' case_bndr alts') - where - ps_alt (con,bndrs,rhs) = postSimplExprEta rhs `thenPM` \ rhs' -> - returnPM (con, bndrs, rhs') -postSimplExprEta e = postSimplExpr e `thenPM` \ e' -> - returnPM (etaCoreExpr e') -\end{code} +%************************************************************************ +%* * +\subsection{Glomming} +%* * +%************************************************************************ \begin{code} -funnyParallelOp ParOp = True -funnyParallelOp _ = False -\end{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} %************************************************************************ %* * -\subsection[coreToStg-lits]{Converting literals} +\subsection{The driver for the simplifier} %* * %************************************************************************ -Literals: the NoRep kind need to be de-no-rep'd. -We always replace them with a simple variable, and float a suitable -binding out to the top level. - \begin{code} -litToRep :: Literal -> PostM (Type, CoreExpr) +simplifyPgm :: SimplifierMode + -> [SimplifierSwitch] + -> HscEnv + -> UniqSupply + -> RuleBase + -> ModGuts + -> IO (SimplCount, RuleBase, ModGuts) -- New bindings + +simplifyPgm mode switches hsc_env us rule_base guts + = do { + showPass dflags "Simplify"; + + (termination_msg, it_count, counts_out, rule_base', guts') + <- do_iteration us rule_base 1 (zeroSimplCount dflags) guts; -litToRep (NoRepStr s ty) - = returnPM (ty, rhs) + 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 (mg_binds guts'); + + return (counts_out, rule_base', guts') + } where - rhs = if (any is_NUL (_UNPK_ s)) + dflags = hsc_dflags hsc_env + phase_info = case mode of + SimplGently -> "gentle" + SimplPhase n -> show n + + sw_chkr = isAmongSimpl switches + max_iterations = intSwitchSet sw_chkr MaxSimplifierIterations `orElse` 2 + + do_iteration us rule_base iteration_no counts guts + -- iteration_no is the number of the iteration we are + -- about to begin, with '1' for the first + | iteration_no > max_iterations -- Stop if we've run out of iterations + = do { +#ifdef DEBUG + if max_iterations > 2 then + hPutStr stderr ("NOTE: Simplifier still going after " ++ + show max_iterations ++ + " iterations; bailing out.\n") + else + return (); +#endif + -- Subtract 1 from iteration_no to get the + -- number of iterations we actually completed + return ("Simplifier baled out", iteration_no - 1, counts, rule_base, guts) + } + + -- Try and force thunks off the binds; significantly reduces + -- space usage, especially with -O. JRS, 000620. + | let sz = coreBindsSize (mg_binds guts) in sz == sz + = do { + -- Occurrence analysis + let { short_inds = _scc_ "ZapInd" shortOutIndirections (mg_binds guts) ; + tagged_binds = _scc_ "OccAnal" occurAnalysePgm short_inds } ; - then -- Must cater for NULs in literal string - mkApps (Var unpackCString2Id) - [mkLit (MachStr s), - mkLit (mkMachInt (toInteger (_LENGTH_ s)))] + dumpIfSet_dyn dflags Opt_D_dump_occur_anal "Short indirections" + (pprCoreBindings short_inds); - else -- No NULs in the string - App (Var unpackCStringId) (mkLit (MachStr s)) + dumpIfSet_dyn dflags Opt_D_dump_occur_anal "Occurrence analysis" + (pprCoreBindings tagged_binds); - is_NUL c = c == '\0' -\end{code} + -- Get any new rules, and extend the rule base + -- (on the side this extends the package rule base in the + -- ExternalPackageTable, ready for the next complation + -- in --make mode) + -- We need to do this regularly, because simplification can + -- poke on IdInfo thunks, which in turn brings in new rules + -- behind the scenes. Otherwise there's a danger we'll simply + -- miss the rules for Ids hidden inside imported inlinings + new_rules <- loadImportedRules hsc_env guts ; + let { rule_base' = extendRuleBaseList rule_base new_rules + ; simpl_env = mkSimplEnv mode sw_chkr rule_base' } ; + -- The new rule base Ids are used 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. + + -- Simplify the program + -- 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 (_scc_ "SimplTopBinds" simplTopBinds simpl_env tagged_binds) of { + (binds', counts') -> do { + + let { guts' = guts { mg_binds = binds' } + ; all_counts = counts `plusSimplCount` counts' + ; herald = "Simplifier phase " ++ phase_info ++ + ", iteration " ++ show iteration_no ++ + " out of " ++ show max_iterations + } ; -If an Integer is small enough (Haskell implementations must support -Ints in the range $[-2^29+1, 2^29-1]$), wrap it up in @int2Integer@; -otherwise, wrap with @addr2Integer@. + -- Stop if nothing happened; don't dump output + if isZeroSimplCount counts' then + return ("Simplifier reached fixed point", iteration_no, + all_counts, rule_base', guts') + else do { -\begin{code} -litToRep (NoRepInteger i integer_ty) - = returnPM (integer_ty, rhs) - where - rhs | i > tARGET_MIN_INT && -- Small enough, so start from an Int - i < tARGET_MAX_INT - = Con (DataCon smallIntegerDataCon) [Con (Literal (mkMachInt i)) []] - - | otherwise -- Big, so start from a string - = App (Var addr2IntegerId) (Con (Literal (MachStr (_PK_ (show i)))) []) - - -litToRep (NoRepRational r rational_ty) - = postSimplExpr (mkLit (NoRepInteger (numerator r) integer_ty)) `thenPM` \ num_arg -> - postSimplExpr (mkLit (NoRepInteger (denominator r) integer_ty)) `thenPM` \ denom_arg -> - returnPM (rational_ty, mkConApp ratio_data_con [Type integer_ty, num_arg, denom_arg]) - where - (ratio_data_con, integer_ty) - = case (splitAlgTyConApp_maybe rational_ty) of - Just (tycon, [i_ty], [con]) - -> ASSERT(isIntegerTy i_ty && getUnique tycon == ratioTyConKey) - (con, i_ty) + -- Dump the result of this iteration + dumpIfSet_dyn dflags Opt_D_dump_simpl_iterations herald + (pprSimplCount counts') ; - _ -> (panic "ratio_data_con", panic "integer_ty") + endPass dflags herald Opt_D_dump_simpl_iterations binds' ; -litToRep other_lit = returnPM (literalType other_lit, mkLit other_lit) + -- Loop + do_iteration us2 rule_base' (iteration_no + 1) all_counts guts' + } } } } + where + (us1, us2) = splitUniqSupply us \end{code} %************************************************************************ %* * -\subsection{The monad} + Top-level occurrence analysis + [In here, not OccurAnal, because it uses + Rules.lhs, which depends on OccurAnal] %* * %************************************************************************ +In @occAnalPgm@ we do indirection-shorting. That is, if we have this: + + x_local = + ...bindings... + x_exported = x_local + +where x_exported is exported, and x_local is not, then we replace it with this: + + x_exported = + x_local = x_exported + ...bindings... + +Without this we never get rid of the x_exported = x_local thing. This +save a gratuitous jump (from \tr{x_exported} to \tr{x_local}), and +makes strictness information propagate better. This used to happen in +the final phase, but it's tidier to do it here. + +STRICTNESS: if we have done strictness analysis, we want the strictness info on +x_local to transfer to x_exported. Hence the copyIdInfo call. + +RULES: we want to *add* any RULES for x_local to x_exported. + +Note [Rules and indirection-zapping] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Problem: what if x_exported has a RULE that mentions something in ...bindings...? +Then the things mentioned can be out of scope! Solution + a) Make sure that in this pass the usage-info from x_exported is + available for ...bindings... + b) If there are any such RULES, rec-ify the entire top-level. + It'll get sorted out next time round + +Messing up the rules +~~~~~~~~~~~~~~~~~~~~ +The example that went bad on me at one stage was this one: + + iterate :: (a -> a) -> a -> [a] + [Exported] + iterate = iterateList + + iterateFB c f x = x `c` iterateFB c f (f x) + iterateList f x = x : iterateList f (f x) + [Not exported] + + {-# RULES + "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x) + "iterateFB" iterateFB (:) = iterateList + #-} + +This got shorted out to: + + iterateList :: (a -> a) -> a -> [a] + iterateList = iterate + + iterateFB c f x = x `c` iterateFB c f (f x) + iterate f x = x : iterate f (f x) + + {-# RULES + "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x) + "iterateFB" iterateFB (:) = iterate + #-} + +And now we get an infinite loop in the rule system + iterate f x -> build (\cn -> iterateFB c f x) + -> iterateFB (:) f x + -> iterate f x + +Tiresome old solution: + don't do shorting out if f has rewrite rules (see shortableIdInfo) + +New solution (I think): + use rule switching-off pragmas to get rid + of iterateList in the first place + + +Other remarks +~~~~~~~~~~~~~ +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} + +We rely on prior eta reduction to simplify things like +\begin{verbatim} + x_exported = /\ tyvars -> x_local tyvars +==> + x_exported = x_local +\end{verbatim} +Hence,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. + \begin{code} -type PostM a = Bool -- True <=> inside a *value* lambda - -> (UniqSupply, Bag CoreBind) -- Unique supply and Floats in - -> (a, (UniqSupply, Bag CoreBind)) - -initPM :: UniqSupply -> PostM a -> a -initPM us m - = case m False {- not inside lambda -} (us, emptyBag) of - (result, _) -> result - -returnPM v in_lam usf = (v, usf) -thenPM m k in_lam usf = case m in_lam usf of - (r, usf') -> k r in_lam usf' - -mapPM f [] = returnPM [] -mapPM f (x:xs) = f x `thenPM` \ r -> - mapPM f xs `thenPM` \ rs -> - returnPM (r:rs) - -insideLambda :: CoreBndr -> PostM a -> PostM a -insideLambda bndr m in_lam usf | isId bndr = m True usf - | otherwise = m in_lam usf - -getInsideLambda :: PostM Bool -getInsideLambda in_lam usf = (in_lam, usf) - -getFloatsPM :: PostM a -> PostM (a, Bag CoreBind) -getFloatsPM m in_lam (us, floats) - = let - (a, (us', floats')) = m in_lam (us, emptyBag) - in - ((a, floats'), (us', floats)) - -addTopFloat :: Type -> CoreExpr -> PostM Id -addTopFloat lit_ty lit_rhs in_lam (us, floats) - = let - (us1, us2) = splitUniqSupply us - uniq = uniqFromSupply us1 - lit_id = mkSysLocal SLIT("lf") uniq lit_ty - in - (lit_id, (us2, floats `snocBag` NonRec lit_id lit_rhs)) -\end{code} +type IndEnv = IdEnv Id -- Maps local_id -> exported_id +shortOutIndirections :: [CoreBind] -> [CoreBind] +shortOutIndirections binds + | isEmptyVarEnv ind_env = binds + | no_need_to_flatten = binds' + | otherwise = [Rec (flattenBinds binds')] -- See Note [Rules and indirect-zapping] + where + ind_env = makeIndEnv binds + exp_ids = varSetElems ind_env + exp_id_set = mkVarSet exp_ids + no_need_to_flatten = all (null . rulesRules . idSpecialisation) exp_ids + binds' = concatMap zap binds + + zap (NonRec bndr rhs) = [NonRec b r | (b,r) <- zapPair (bndr,rhs)] + zap (Rec pairs) = [Rec (concatMap zapPair pairs)] + + zapPair (bndr, rhs) + | bndr `elemVarSet` exp_id_set = [] + | Just exp_id <- lookupVarEnv ind_env bndr = [(transferIdInfo exp_id bndr, rhs), + (bndr, Var exp_id)] + | otherwise = [(bndr,rhs)] + +makeIndEnv :: [CoreBind] -> IndEnv +makeIndEnv binds + = foldr add_bind emptyVarEnv binds + where + add_bind :: CoreBind -> IndEnv -> IndEnv + add_bind (NonRec exported_id rhs) env = add_pair (exported_id, rhs) env + add_bind (Rec pairs) env = foldr add_pair env pairs + + add_pair :: (Id,CoreExpr) -> IndEnv -> IndEnv + add_pair (exported_id, Var local_id) env + | shortMeOut env exported_id local_id = extendVarEnv env local_id exported_id + add_pair (exported_id, rhs) env + = env + +shortMeOut ind_env exported_id local_id +-- The if-then-else stuff is just so I can get a pprTrace to see +-- how often I don't get shorting out becuase of IdInfo stuff + = if isExportedId exported_id && -- Only if this is exported + + isLocalId local_id && -- Only if this one is defined in this + -- module, so that we *can* change its + -- binding to be the exported thing! + + not (isExportedId local_id) && -- Only if this one is not itself exported, + -- since the transformation will nuke it + + not (local_id `elemVarEnv` ind_env) -- Only if not already substituted for + then + True + +{- No longer needed + if isEmptyCoreRules (specInfo (idInfo exported_id)) -- Only if no rules + then True -- See note on "Messing up rules" + else +#ifdef DEBUG + pprTrace "shortMeOut:" (ppr exported_id) +#endif + False +-} + else + False + +----------------- +transferIdInfo :: Id -> Id -> Id +transferIdInfo exported_id local_id + = modifyIdInfo transfer exported_id + where + local_info = idInfo local_id + transfer exp_info = exp_info `setNewStrictnessInfo` newStrictnessInfo local_info + `setWorkerInfo` workerInfo local_info + `setSpecInfo` addRules exported_id (specInfo exp_info) + (rulesRules (specInfo local_info)) +\end{code}