X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreTidy.lhs;h=bb7992d32ad55327ddc7d64a98ff46c18e73b688;hb=bcd00882317241e2ae8c83e806aa05091c6d53a3;hp=abe5c73e4270aa1e550e6f7041cc89ae7ed5b303;hpb=db95d6e8d319b0c5cee1ccc23751e8190152ade3;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreTidy.lhs b/ghc/compiler/coreSyn/CoreTidy.lhs index abe5c73..bb7992d 100644 --- a/ghc/compiler/coreSyn/CoreTidy.lhs +++ b/ghc/compiler/coreSyn/CoreTidy.lhs @@ -11,84 +11,133 @@ module CoreTidy ( #include "HsVersions.h" -import CmdLineOpts ( DynFlags, DynFlag(..), opt_UsageSPOn, dopt ) +import CmdLineOpts ( DynFlags, DynFlag(..), opt_OmitInterfacePragmas ) import CoreSyn -import CoreUnfold ( noUnfolding ) +import CoreUnfold ( noUnfolding, mkTopUnfolding, okToUnfoldInHiFile ) +import CoreUtils ( exprArity, exprIsValue ) +import CoreFVs ( ruleSomeFreeVars, exprSomeFreeVars ) import CoreLint ( showPass, endPass ) -import UsageSPInf ( doUsageSPInf ) import VarEnv import VarSet import Var ( Id, Var ) -import Id ( idType, idInfo, idName, - mkVanillaId, mkId, exportWithOrigOccName, - idStrictness, setIdStrictness, - idDemandInfo, setIdDemandInfo, +import Id ( idType, idInfo, idName, isExportedId, + idCafInfo, mkId, isLocalId, isImplicitId, + idFlavour, modifyIdInfo ) -import IdInfo ( specInfo, setSpecInfo, - setUnfoldingInfo, setDemandInfo, - workerInfo, setWorkerInfo, WorkerInfo(..) +import IdInfo {- loads of stuff -} +import Name ( getOccName, nameOccName, globaliseName, setNameOcc, + localiseName, mkLocalName, isGlobalName ) -import Demand ( wwLazy ) -import Name ( getOccName, tidyTopName, mkLocalName ) -import OccName ( initTidyOccEnv, tidyOccName ) +import OccName ( TidyOccEnv, initTidyOccEnv, tidyOccName ) import Type ( tidyTopType, tidyType, tidyTyVar ) -import Module ( Module ) -import UniqSupply ( mkSplitUniqSupply ) -import Unique ( Uniquable(..) ) +import Module ( Module, moduleName ) +import PrimOp ( PrimOp(..), setCCallUnique ) +import HscTypes ( PersistentCompilerState( pcs_PRS ), + PersistentRenamerState( prsOrig ), + NameSupply( nsNames ), OrigNameCache + ) +import UniqSupply +import FiniteMap ( lookupFM, addToFM ) +import Maybes ( maybeToBool, orElse ) import ErrUtils ( showPass ) import SrcLoc ( noSrcLoc ) +import UniqFM ( mapUFM ) +import Outputable +import FastTypes +import List ( partition ) import Util ( mapAccumL ) \end{code} %************************************************************************ -%* * -\subsection{Tidying core} -%* * +%* * +\subsection{What goes on} +%* * %************************************************************************ -Several tasks are done by @tidyCorePgm@ - -1. If @opt_UsageSPOn@ then compute usage information (which is - needed by Core2Stg). ** NOTE _scc_ HERE ** - Do this first, because it may introduce new binders. - -2. Make certain top-level bindings into Globals. The point is that - Global things get externally-visible labels at code generation - time - +[SLPJ: 19 Nov 00] + +The plan is this. + +Step 1: Figure out external Ids +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +First we figure out which Ids are "external" Ids. An +"external" Id is one that is visible from outside the compilation +unit. These are + a) the user exported ones + b) ones mentioned in the unfoldings, workers, + or rules of externally-visible ones +This exercise takes a sweep of the bindings bottom to top. Actually, +in Step 2 we're also going to need to know which Ids should be +exported with their unfoldings, so we produce not an IdSet but an +IdEnv Bool + + +Step 2: Tidy the program +~~~~~~~~~~~~~~~~~~~~~~~~ +Next we traverse the bindings top to bottom. For each top-level +binder + + - Make all external Ids have Global names and vice versa + This is used by the code generator to decide whether + to make the label externally visible + + - Give external ids a "tidy" occurrence name. This means + we can print them in interface files without confusing + "x" (unique 5) with "x" (unique 10). + + - Give external Ids the same Unique as they had before + if the name is in the renamer's name cache + + - Clone all local Ids. This means that Tidy Core has the property + that all Ids are unique, rather than the weaker guarantee of + no clashes which the simplifier provides. + + - Give each dynamic CCall occurrence a fresh unique; this is + rather like the cloning step above. + + - Give the Id its UTTERLY FINAL IdInfo; in ptic, + * Its flavour becomes ConstantId, reflecting the fact that + from now on we regard it as a constant, not local, Id + + * its unfolding, if it should have one + + * its arity, computed from the number of visible lambdas + + * its CAF info, computed from what is free in its RHS -3. 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.] + +Finally, substitute these new top-level binders consistently +throughout, including in unfoldings. We also tidy binders in +RHSs, so that they print nicely in interfaces. \begin{code} tidyCorePgm :: DynFlags -> Module + -> PersistentCompilerState -> [CoreBind] -> [IdCoreRule] - -> IO ([CoreBind], [IdCoreRule]) -tidyCorePgm dflags module_name binds_in orphans_in - = do - us <- mkSplitUniqSupply 'u' + -> IO (PersistentCompilerState, [CoreBind], [IdCoreRule]) +tidyCorePgm dflags mod pcs binds_in orphans_in + = do { showPass dflags "Tidy Core" + + ; let ext_ids = findExternalSet binds_in orphans_in + + ; us <- mkSplitUniqSupply 't' -- for "tidy" - showPass dflags "Tidy Core" + ; let ((us1, orig_env', occ_env, subst_env), binds_out) + = mapAccumL (tidyTopBind mod ext_ids) + (init_tidy_env us) binds_in - binds_in1 <- if opt_UsageSPOn - then _scc_ "CoreUsageSPInf" - doUsageSPInf dflags us binds_in - else return binds_in + ; let (orphans_out, _) + = initUs us1 (tidyIdRules (occ_env,subst_env) orphans_in) - let (tidy_env1, binds_out) = mapAccumL (tidyBind (Just module_name)) - init_tidy_env binds_in1 - orphans_out = tidyIdRules tidy_env1 orphans_in + ; let prs' = prs { prsOrig = orig { nsNames = orig_env' } } + pcs' = pcs { pcs_PRS = prs' } - endPass dflags "Tidy Core" (dopt Opt_D_dump_simpl dflags || - dopt Opt_D_verbose_core2core dflags) - binds_out + ; endPass dflags "Tidy Core" Opt_D_dump_simpl binds_out - return (binds_out, orphans_out) + ; return (pcs', binds_out, orphans_out) + } where -- We also make sure to avoid any exported binders. Consider -- f{-u1-} = 1 -- Local decl @@ -98,169 +147,520 @@ tidyCorePgm dflags module_name binds_in orphans_in -- 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. tidyTopId then does a no-op on exported binders. - init_tidy_env = (initTidyOccEnv avoids, emptyVarEnv) - avoids = [getOccName bndr | bndr <- bindersOfBinds binds_in, - exportWithOrigOccName 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') = tidy_bndr maybe_mod env' env bndr - rhs' = tidyExpr env' rhs - -- We use env' when tidying the RHS even though it's not - -- strictly necessary; it makes the code pretty hard to read - -- if we don't! - 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 (tidy_bndr maybe_mod env') env bndrs - rhss' = map (tidyExpr env') rhss - in - (env', Rec (zip bndrs' rhss')) - -tidyExpr env (Type ty) = Type (tidyType env ty) -tidyExpr env (Lit lit) = Lit lit -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') = tidyBndr env b - -tidyExpr env (Var v) = Var (tidyVarOcc env v) - -tidyExpr env (Lam b e) = Lam b' (tidyExpr env' e) - where - (env', b') = tidyBndr env b - -tidyAlt env (con, vs, rhs) = (con, vs', tidyExpr env' rhs) - where - (env', vs') = tidyBndrs env vs + prs = pcs_PRS pcs + orig = prsOrig prs + orig_env = nsNames orig -tidyNote env (Coerce t1 t2) = Coerce (tidyType env t1) (tidyType env t2) + init_tidy_env us = (us, orig_env, initTidyOccEnv avoids, emptyVarEnv) + avoids = [getOccName bndr | bndr <- bindersOfBinds binds_in, + isGlobalName (idName bndr)] +\end{code} -tidyNote env note = note -tidyVarOcc (_, var_env) v = case lookupVarEnv var_env v of - Just v' -> v' - Nothing -> v -\end{code} +%************************************************************************ +%* * +\subsection{Step 1: finding externals} +%* * +%************************************************************************ \begin{code} -tidy_bndr (Just mod) env_idinfo env var = tidyTopId mod env env_idinfo var -tidy_bndr Nothing env_idinfo env var = tidyBndr env var +findExternalSet :: [CoreBind] -> [IdCoreRule] + -> IdEnv Bool -- True <=> show unfolding + -- Step 1 from the notes above +findExternalSet binds orphan_rules + = foldr find init_needed binds + where + orphan_rule_ids :: IdSet + orphan_rule_ids = unionVarSets [ ruleSomeFreeVars isIdAndLocal rule + | (_, rule) <- orphan_rules] + init_needed :: IdEnv Bool + init_needed = mapUFM (\_ -> False) orphan_rule_ids + -- The mapUFM is a bit cheesy. It is a cheap way + -- to turn the set of orphan_rule_ids, which we use to initialise + -- the sweep, into a mapping saying 'don't expose unfolding' + -- (When we come to the binding site we may change our mind, of course.) + + find (NonRec id rhs) needed + | need_id needed id = addExternal (id,rhs) needed + | otherwise = needed + find (Rec prs) needed = find_prs prs needed + + -- For a recursive group we have to look for a fixed point + find_prs prs needed + | null needed_prs = needed + | otherwise = find_prs other_prs new_needed + where + (needed_prs, other_prs) = partition (need_pr needed) prs + new_needed = foldr addExternal needed needed_prs + + -- The 'needed' set contains the Ids that are needed by earlier + -- interface file emissions. If the Id isn't in this set, and isn't + -- exported, there's no need to emit anything + need_id needed_set id = id `elemVarEnv` needed_set || isExportedId id + need_pr needed_set (id,rhs) = need_id needed_set id + +isIdAndLocal id = isId id && isLocalId id + +addExternal :: (Id,CoreExpr) -> IdEnv Bool -> IdEnv Bool +-- The Id is needed; extend the needed set +-- with it and its dependents (free vars etc) +addExternal (id,rhs) needed + = extendVarEnv (foldVarSet add_occ needed new_needed_ids) + id show_unfold + where + add_occ id needed = extendVarEnv needed id False + -- "False" because we don't know we need the Id's unfolding + -- We'll override it later when we find the binding site + + new_needed_ids | opt_OmitInterfacePragmas = emptyVarSet + | otherwise = worker_ids `unionVarSet` + unfold_ids `unionVarSet` + spec_ids + + idinfo = idInfo id + dont_inline = isNeverInlinePrag (inlinePragInfo idinfo) + loop_breaker = isLoopBreaker (occInfo idinfo) + bottoming_fn = isBottomingStrictness (strictnessInfo idinfo) + spec_ids = rulesRhsFreeVars (specInfo idinfo) + worker_info = workerInfo idinfo + + -- Stuff to do with the Id's unfolding + -- The simplifier has put an up-to-date unfolding + -- in the IdInfo, but the RHS will do just as well + unfolding = unfoldingInfo idinfo + rhs_is_small = not (neverUnfold unfolding) + + -- We leave the unfolding there even if there is a worker + -- In GHCI the unfolding is used by importers + -- When writing an interface file, we omit the unfolding + -- if there is a worker + show_unfold = not bottoming_fn && -- Not necessary + not dont_inline && + not loop_breaker && + rhs_is_small && -- Small enough + okToUnfoldInHiFile rhs -- No casms etc + + unfold_ids | show_unfold = exprSomeFreeVars isIdAndLocal rhs + | otherwise = emptyVarSet + + worker_ids = case worker_info of + HasWorker work_id _ -> unitVarSet work_id + otherwise -> emptyVarSet \end{code} - %************************************************************************ %* * -\subsection{Tidying up a binder} +\subsection{Step 2: top-level tidying} %* * %************************************************************************ -\begin{code} -tidyBndr :: TidyEnv -> Var -> (TidyEnv, Var) -tidyBndr env var | isTyVar var = tidyTyVar env var - | otherwise = tidyId env var -tidyBndrs :: TidyEnv -> [Var] -> (TidyEnv, [Var]) -tidyBndrs env vars = mapAccumL tidyBndr env vars +\begin{code} +type TopTidyEnv = (UniqSupply, OrigNameCache, TidyOccEnv, VarEnv Var) + +-- TopTidyEnv: when tidying we need to know +-- * orig_env: Any pre-ordained Names. These may have arisen because the +-- renamer read in an interface file mentioning M.$wf, say, +-- and assigned it unique r77. If, on this compilation, we've +-- invented an Id whose name is $wf (but with a different unique) +-- we want to rename it to have unique r77, so that we can do easy +-- comparisons with stuff from the interface file +-- +-- * occ_env: The TidyOccEnv, which tells us which local occurrences +-- are 'used' +-- +-- * subst_env: A Var->Var mapping that substitutes the new Var for the old +-- +-- * uniqsuppy: so we can clone any Ids with non-preordained names. +-- +\end{code} -tidyId :: TidyEnv -> Id -> (TidyEnv, Id) -tidyId 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' = mkVanillaId name' ty' - `setIdStrictness` idStrictness id - `setIdDemandInfo` idDemandInfo id - -- 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. - -- - -- The exception is strictness and demand info, which - -- is used to decide whether to use let or case for - -- function arguments and let bindings - var_env' = extendVarEnv var_env id id' - in - ((tidy_env', var_env'), id') - -tidyTopId :: Module -> TidyEnv -> TidyEnv -> Id -> (TidyEnv, Id) +\begin{code} +tidyTopBind :: Module + -> IdEnv Bool -- Domain = Ids that should be external + -- True <=> their unfolding is external too + -> TopTidyEnv -> CoreBind + -> (TopTidyEnv, CoreBind) + +tidyTopBind mod ext_ids env (NonRec bndr rhs) + = ((us2,orig,occ,subst) , NonRec bndr' rhs') + where + ((us1,orig,occ,subst), bndr') + = tidyTopBinder mod ext_ids tidy_env rhs' caf_info env bndr + tidy_env = (occ,subst) + caf_info = hasCafRefs (const True) rhs' + (rhs',us2) = initUs us1 (tidyExpr tidy_env rhs) + +tidyTopBind mod ext_ids env (Rec prs) + = (final_env, Rec prs') + where + (final_env@(_,_,occ,subst), prs') = mapAccumL do_one env prs + final_tidy_env = (occ,subst) + + do_one env (bndr,rhs) + = ((us',orig,occ,subst), (bndr',rhs')) + where + ((us,orig,occ,subst), bndr') + = tidyTopBinder mod ext_ids final_tidy_env rhs' caf_info env bndr + (rhs', us') = initUs us (tidyExpr final_tidy_env rhs) + + -- the CafInfo for a recursive group says whether *any* rhs in + -- the group may refer indirectly to a CAF (because then, they all do). + (bndrs, rhss) = unzip prs' + caf_info = hasCafRefss pred rhss + pred v = v `notElem` bndrs + + +tidyTopBinder :: Module -> IdEnv Bool + -> TidyEnv -> CoreExpr -> CafInfo + -- The TidyEnv is used to tidy the IdInfo + -- The expr is the already-tided RHS + -- Both are knot-tied: don't look at them! + -> TopTidyEnv -> Id -> (TopTidyEnv, Id) + +tidyTopBinder mod ext_ids tidy_env rhs caf_info + env@(us, orig_env2, occ_env2, subst_env2) id + + | isImplicitId id -- Don't mess with constructors, + = (env, id) -- record selectors, and the like + + | otherwise + -- This function is the heart of Step 2 -- The second env is the one to use for the IdInfo -- It's necessary because when we are dealing with a recursive -- group, a variable late in the group might be mentioned -- in the IdInfo of one early in the group -tidyTopId mod env@(tidy_env, var_env) env_idinfo id - = -- Top level variables - let - (tidy_env', name') = tidyTopName mod tidy_env (idIsExported id) (idName id) - ty' = tidyTopType (idType id) - idinfo' = tidyIdInfo env_idinfo (idInfo id) - id' = mkId name' ty' idinfo' - var_env' = extendVarEnv var_env id id' - in - ((tidy_env', var_env'), id') + + -- The rhs is already tidied + + = ((us_r, orig_env', occ_env', subst_env'), id') + where + (us_l, us_r) = splitUniqSupply us + + (orig_env', occ_env', name') = tidyTopName mod orig_env2 occ_env2 + is_external + (idName id) + ty' = tidyTopType (idType id) + idinfo' = tidyIdInfo us_l tidy_env + is_external unfold_info arity_info caf_info id + + id' = mkId name' ty' idinfo' + subst_env' = extendVarEnv subst_env2 id id' + + maybe_external = lookupVarEnv ext_ids id + is_external = maybeToBool maybe_external + + -- Expose an unfolding if ext_ids tells us to + show_unfold = maybe_external `orElse` False + unfold_info | show_unfold = mkTopUnfolding rhs + | otherwise = noUnfolding + + arity_info = exprArity rhs + + +tidyIdInfo us tidy_env is_external unfold_info arity_info caf_info id + | opt_OmitInterfacePragmas || not is_external + -- No IdInfo if the Id isn't external, or if we don't have -O + = mkIdInfo new_flavour caf_info + `setStrictnessInfo` strictnessInfo core_idinfo + `setArityInfo` ArityExactly arity_info + -- Keep strictness, arity and CAF info; it's used by the code generator + + | otherwise + = let (rules', _) = initUs us (tidyRules tidy_env (specInfo core_idinfo)) + in + mkIdInfo new_flavour caf_info + `setCprInfo` cprInfo core_idinfo + `setStrictnessInfo` strictnessInfo core_idinfo + `setInlinePragInfo` inlinePragInfo core_idinfo + `setUnfoldingInfo` unfold_info + `setWorkerInfo` tidyWorker tidy_env arity_info (workerInfo core_idinfo) + `setSpecInfo` rules' + `setArityInfo` ArityExactly arity_info + -- this is the final IdInfo, it must agree with the + -- code finally generated (i.e. NO more transformations + -- after this!). + where + core_idinfo = idInfo id + + -- A DFunId must stay a DFunId, so that we can gather the + -- DFunIds up later. Other local things become ConstantIds. + new_flavour = case flavourInfo core_idinfo of + VanillaId -> ConstantId + ExportedId -> ConstantId + ConstantId -> ConstantId -- e.g. Default methods + DictFunId -> DictFunId + flavour -> pprTrace "tidyIdInfo" (ppr id <+> ppFlavourInfo flavour) + flavour + + +-- This is where we set names to local/global based on whether they really are +-- externally visible (see comment at the top of this module). If the name +-- was previously local, we have to give it a unique occurrence name if +-- we intend to globalise it. +tidyTopName mod orig_env occ_env external name + | global && internal = (orig_env, occ_env, localiseName name) + + | local && internal = (orig_env, occ_env', setNameOcc name occ') + -- Even local, internal names must get a unique occurrence, because + -- if we do -split-objs we globalise the name later, n the code generator + + | global && external = (orig_env, occ_env, name) + -- Global names are assumed to have been allocated by the renamer, + -- so they already have the "right" unique + + | local && external = case lookupFM orig_env key of + Just orig -> (orig_env, occ_env', orig) + Nothing -> (addToFM orig_env key global_name, occ_env', global_name) + -- If we want to globalise a currently-local name, check + -- whether we have already assigned a unique for it. + -- If so, use it; if not, extend the table + + where + (occ_env', occ') = tidyOccName occ_env (nameOccName name) + key = (moduleName mod, occ') + global_name = globaliseName (setNameOcc name occ') mod + global = isGlobalName name + local = not global + internal = not external + +------------ Worker -------------- +-- We only treat a function as having a worker if +-- the exported arity (which is now the number of visible lambdas) +-- is the same as the arity at the moment of the w/w split +-- If so, we can safely omit the unfolding inside the wrapper, and +-- instead re-generate it from the type/arity/strictness info +-- But if the arity has changed, we just take the simple path and +-- put the unfolding into the interface file, forgetting the fact +-- that it's a wrapper. +-- +-- How can this happen? Sometimes we get +-- f = coerce t (\x y -> $wf x y) +-- at the moment of w/w split; but the eta reducer turns it into +-- f = coerce t $wf +-- which is perfectly fine except that the exposed arity so far as +-- the code generator is concerned (zero) differs from the arity +-- when we did the split (2). +-- +-- All this arises because we use 'arity' to mean "exactly how many +-- top level lambdas are there" in interface files; but during the +-- compilation of this module it means "how many things can I apply +-- this to". +tidyWorker tidy_env real_arity (HasWorker work_id wrap_arity) + | real_arity == wrap_arity + = HasWorker (tidyVarOcc tidy_env work_id) wrap_arity +tidyWorker tidy_env real_arity other + = NoWorker + +------------ Rules -------------- +tidyIdRules :: TidyEnv -> [IdCoreRule] -> UniqSM [IdCoreRule] +tidyIdRules env [] = returnUs [] +tidyIdRules env ((fn,rule) : rules) + = tidyRule env rule `thenUs` \ rule -> + tidyIdRules env rules `thenUs` \ rules -> + returnUs ((tidyVarOcc env fn, rule) : rules) + +tidyRules :: TidyEnv -> CoreRules -> UniqSM CoreRules +tidyRules env (Rules rules fvs) + = mapUs (tidyRule env) rules `thenUs` \ rules -> + returnUs (Rules rules (foldVarSet tidy_set_elem emptyVarSet fvs)) + where + tidy_set_elem var new_set = extendVarSet new_set (tidyVarOcc env var) + +tidyRule :: TidyEnv -> CoreRule -> UniqSM CoreRule +tidyRule env rule@(BuiltinRule _) = returnUs rule +tidyRule env (Rule name vars tpl_args rhs) + = tidyBndrs env vars `thenUs` \ (env', vars) -> + mapUs (tidyExpr env') tpl_args `thenUs` \ tpl_args -> + tidyExpr env' rhs `thenUs` \ rhs -> + returnUs (Rule name vars tpl_args rhs) \end{code} +%************************************************************************ +%* * +\subsection{Step 2: inner tidying +%* * +%************************************************************************ + \begin{code} --- tidyIdInfo does these things: --- a) tidy the specialisation info and worker info (if any) --- b) zap the unfolding and demand info --- The latter two are to avoid space leaks +tidyBind :: TidyEnv + -> CoreBind + -> UniqSM (TidyEnv, CoreBind) +tidyBind env (NonRec bndr rhs) + = tidyBndrWithRhs env (bndr,rhs) `thenUs` \ (env', bndr') -> + tidyExpr env' rhs `thenUs` \ rhs' -> + returnUs (env', NonRec bndr' rhs') + +tidyBind env (Rec prs) + = mapAccumLUs tidyBndrWithRhs env prs `thenUs` \ (env', bndrs') -> + mapUs (tidyExpr env') (map snd prs) `thenUs` \ rhss' -> + returnUs (env', Rec (zip bndrs' rhss')) + +tidyExpr env (Var v) + = fiddleCCall v `thenUs` \ v -> + returnUs (Var (tidyVarOcc env v)) + +tidyExpr env (Type ty) = returnUs (Type (tidyType env ty)) +tidyExpr env (Lit lit) = returnUs (Lit lit) + +tidyExpr env (App f a) + = tidyExpr env f `thenUs` \ f -> + tidyExpr env a `thenUs` \ a -> + returnUs (App f a) + +tidyExpr env (Note n e) + = tidyExpr env e `thenUs` \ e -> + returnUs (Note (tidyNote env n) e) + +tidyExpr env (Let b e) + = tidyBind env b `thenUs` \ (env', b') -> + tidyExpr env' e `thenUs` \ e -> + returnUs (Let b' e) + +tidyExpr env (Case e b alts) + = tidyExpr env e `thenUs` \ e -> + tidyBndr env b `thenUs` \ (env', b) -> + mapUs (tidyAlt env') alts `thenUs` \ alts -> + returnUs (Case e b alts) + +tidyExpr env (Lam b e) + = tidyBndr env b `thenUs` \ (env', b) -> + tidyExpr env' e `thenUs` \ e -> + returnUs (Lam b e) + + +tidyAlt env (con, vs, rhs) + = tidyBndrs env vs `thenUs` \ (env', vs) -> + tidyExpr env' rhs `thenUs` \ rhs -> + returnUs (con, vs, rhs) -tidyIdInfo env info - = info5 - where - rules = specInfo info +tidyNote env (Coerce t1 t2) = Coerce (tidyType env t1) (tidyType env t2) +tidyNote env note = note +\end{code} - info2 | isEmptyCoreRules rules = info - | otherwise = info `setSpecInfo` tidyRules env rules - - info3 = info2 `setUnfoldingInfo` noUnfolding - info4 = info3 `setDemandInfo` wwLazy - info5 = case workerInfo info of - NoWorker -> info4 - HasWorker w a -> info4 `setWorkerInfo` HasWorker (tidyVarOcc env w) a +%************************************************************************ +%* * +\subsection{Tidying up non-top-level binders} +%* * +%************************************************************************ + +\begin{code} +tidyVarOcc (_, var_env) v = case lookupVarEnv var_env v of + Just v' -> v' + Nothing -> v + +-- tidyBndr is used for lambda and case binders +tidyBndr :: TidyEnv -> Var -> UniqSM (TidyEnv, Var) +tidyBndr env var + | isTyVar var = returnUs (tidyTyVar env var) + | otherwise = tidyId env var vanillaIdInfo + +tidyBndrs :: TidyEnv -> [Var] -> UniqSM (TidyEnv, [Var]) +tidyBndrs env vars = mapAccumLUs tidyBndr env vars + +-- tidyBndrWithRhs is used for let binders +tidyBndrWithRhs :: TidyEnv -> (Var, CoreExpr) -> UniqSM (TidyEnv, Var) +tidyBndrWithRhs env (id,rhs) + = tidyId env id idinfo + where + idinfo = vanillaIdInfo `setArityInfo` ArityExactly (exprArity rhs) + -- 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. -tidyIdRules :: TidyEnv -> [IdCoreRule] -> [IdCoreRule] -tidyIdRules env rules - = [ (tidyVarOcc env fn, tidyRule env rule) | (fn,rule) <- rules ] +tidyId :: TidyEnv -> Id -> IdInfo -> UniqSM (TidyEnv, Id) +tidyId env@(tidy_env, var_env) id idinfo + = -- Non-top-level variables + getUniqueUs `thenUs` \ uniq -> + 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 uniq occ' noSrcLoc + (tidy_env', occ') = tidyOccName tidy_env (getOccName id) + ty' = tidyType (tidy_env,var_env) (idType id) + id' = mkId name' ty' idinfo + var_env' = extendVarEnv var_env id id' + in + returnUs ((tidy_env', var_env'), id') + + +fiddleCCall id + = case idFlavour id of + PrimOpId (CCallOp ccall) -> + -- Make a guaranteed unique name for a dynamic ccall. + getUniqueUs `thenUs` \ uniq -> + returnUs (modifyIdInfo (`setFlavourInfo` + PrimOpId (CCallOp (setCCallUnique ccall uniq))) id) + other_flavour -> + returnUs id +\end{code} -tidyRules :: TidyEnv -> CoreRules -> CoreRules -tidyRules env (Rules rules fvs) - = Rules (map (tidyRule env) rules) - (foldVarSet tidy_set_elem emptyVarSet fvs) - where - tidy_set_elem var new_set = extendVarSet new_set (tidyVarOcc env var) +%************************************************************************ +%* * +\subsection{Figuring out CafInfo for an expression} +%* * +%************************************************************************ -tidyRule :: TidyEnv -> CoreRule -> CoreRule -tidyRule env rule@(BuiltinRule _) = rule -tidyRule env (Rule name vars tpl_args rhs) - = (Rule name vars' (map (tidyExpr env') tpl_args) (tidyExpr env' rhs)) - where - (env', vars') = tidyBndrs env vars +\begin{code} +hasCafRefs :: (Id -> Bool) -> CoreExpr -> CafInfo +hasCafRefss :: (Id -> Bool) -> [CoreExpr] -> CafInfo + -- predicate returns True for a given Id if we look at this Id when + -- calculating the result. Used to *avoid* looking at the CafInfo + -- field for an Id that is part of the current recursive group. + +hasCafRefs p expr = if isCAF expr || isFastTrue (cafRefs p expr) + then MayHaveCafRefs + else NoCafRefs + + -- used for recursive groups. The whole group is set to + -- "MayHaveCafRefs" if at least one of the group is a CAF or + -- refers to any CAFs. +hasCafRefss p exprs = if any isCAF exprs || isFastTrue (cafRefss p exprs) + then MayHaveCafRefs + else NoCafRefs + +cafRefs p (Var id) + | p id + = case idCafInfo id of + NoCafRefs -> fastBool False + MayHaveCafRefs -> fastBool True + | otherwise + = fastBool False + +cafRefs p (Lit l) = fastBool False +cafRefs p (App f a) = cafRefs p f `fastOr` cafRefs p a +cafRefs p (Lam x e) = cafRefs p e +cafRefs p (Let b e) = cafRefss p (rhssOfBind b) `fastOr` cafRefs p e +cafRefs p (Case e bndr alts) = cafRefs p e `fastOr` cafRefss p (rhssOfAlts alts) +cafRefs p (Note n e) = cafRefs p e +cafRefs p (Type t) = fastBool False + +cafRefss p [] = fastBool False +cafRefss p (e:es) = cafRefs p e `fastOr` cafRefss p es + +-- Decide whether a closure looks like a CAF or not. In an effort to +-- keep the number of CAFs (and hence the size of the SRTs) down, we +-- would also like to look at the expression and decide whether it +-- requires a small bounded amount of heap, so we can ignore it as a +-- CAF. In these cases however, we would need to use an additional +-- CAF list to keep track of non-collectable CAFs. + +-- We mark real CAFs as `MayHaveCafRefs' because this information is +-- used to decide whether a particular closure needs to be referenced +-- in an SRT or not. + +isCAF :: CoreExpr -> Bool +isCAF e + | exprIsValue e = False + | otherwise = True + {- ToDo: check type for onceness, i.e. non-updatable thunks? -} + +-- we're assuming here that anything for which exprIsValue is True +-- will be non-updatable. This is true for functions and +-- constructors, but we must make sure that partial applications are +-- compiled as non-updatable closures (which CoreToStg does). \end{code}