X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FstgSyn%2FCoreToStg.lhs;h=824cabaacbd51c1468cf5ea6d56c8143c3a5edfc;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=abcd7dddd615e0826d6f9418d919299ae58ec787;hpb=b854aa77127e57c29ef859c05046adbe30e314f6;p=ghc-hetmet.git diff --git a/ghc/compiler/stgSyn/CoreToStg.lhs b/ghc/compiler/stgSyn/CoreToStg.lhs index abcd7dd..824caba 100644 --- a/ghc/compiler/stgSyn/CoreToStg.lhs +++ b/ghc/compiler/stgSyn/CoreToStg.lhs @@ -1,469 +1,1107 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998 % -%************************************************************************ -%* * -\section[CoreToStg]{Converting core syntax to STG syntax} -%* * -%************************************************************************ +\section[CoreToStg]{Converts Core to STG Syntax} -Convert a @CoreSyntax@ program to a @StgSyntax@ program. +And, as we have the info in hand, we may convert some lets to +let-no-escapes. \begin{code} -module CoreToStg ( topCoreBindsToStg ) where +module CoreToStg ( coreToStg, coreExprToStg ) where #include "HsVersions.h" -import CoreSyn -- input -import StgSyn -- output - -import Bag ( emptyBag, unitBag, unionBags, unionManyBags, bagToList ) -import CoreUtils ( coreExprType ) -import CostCentre ( noCostCentre ) -import Id ( mkSysLocal, idType, isBottomingId, - externallyVisibleId, mkIdWithNewUniq, - - nullIdEnv, addOneToIdEnv, lookupIdEnv, growIdEnvList, - IdEnv, GenId{-instance NamedThing-}, Id - ) -import Literal ( mkMachInt, Literal(..) ) -import PrelVals ( unpackCStringId, unpackCString2Id, - integerZeroId, integerPlusOneId, - integerPlusTwoId, integerMinusOneId - ) -import PrimOp ( PrimOp(..) ) -import SrcLoc ( noSrcLoc ) -import TyCon ( TyCon{-instance Uniquable-} ) -import Type ( splitAlgTyConApp, Type ) -import TysWiredIn ( stringTy ) -import Unique ( integerTyConKey, ratioTyConKey, Unique{-instance Eq-} ) -import UniqSupply -- all of it, really -import Util ( zipLazy ) +import CoreSyn +import CoreUtils ( rhsIsStatic, manifestArity, exprType, findDefault ) +import StgSyn + +import Type +import TyCon ( isAlgTyCon ) +import Id +import Var ( Var, globalIdDetails, idType ) +import TyCon ( isUnboxedTupleTyCon, isPrimTyCon, isFunTyCon, isHiBootTyCon ) +#ifdef ILX +import MkId ( unsafeCoerceId ) +#endif +import IdInfo +import DataCon +import CostCentre ( noCCS ) +import VarSet +import VarEnv +import Maybes ( maybeToBool ) +import Name ( getOccName, isExternalName, nameOccName ) +import OccName ( occNameString, occNameFS ) +import BasicTypes ( Arity ) +import Packages ( HomeModules ) +import StaticFlags ( opt_RuntimeTypes ) import Outputable -import Ratio ( numerator, denominator ) -isLeakFreeType x y = False -- safe option; ToDo +infixr 9 `thenLne` \end{code} +%************************************************************************ +%* * +\subsection[live-vs-free-doc]{Documentation} +%* * +%************************************************************************ - *************** OVERVIEW ********************* +(There is other relevant documentation in codeGen/CgLetNoEscape.) + +The actual Stg datatype is decorated with {\em live variable} +information, as well as {\em free variable} information. The two are +{\em not} the same. Liveness is an operational property rather than a +semantic one. A variable is live at a particular execution point if +it can be referred to {\em directly} again. In particular, a dead +variable's stack slot (if it has one): +\begin{enumerate} +\item +should be stubbed to avoid space leaks, and +\item +may be reused for something else. +\end{enumerate} + +There ought to be a better way to say this. Here are some examples: +\begin{verbatim} + let v = [q] \[x] -> e + in + ...v... (but no q's) +\end{verbatim} + +Just after the `in', v is live, but q is dead. If the whole of that +let expression was enclosed in a case expression, thus: +\begin{verbatim} + case (let v = [q] \[x] -> e in ...v...) of + alts[...q...] +\end{verbatim} +(ie @alts@ mention @q@), then @q@ is live even after the `in'; because +we'll return later to the @alts@ and need it. + +Let-no-escapes make this a bit more interesting: +\begin{verbatim} + let-no-escape v = [q] \ [x] -> e + in + ...v... +\end{verbatim} +Here, @q@ is still live at the `in', because @v@ is represented not by +a closure but by the current stack state. In other words, if @v@ is +live then so is @q@. Furthermore, if @e@ mentions an enclosing +let-no-escaped variable, then {\em its} free variables are also live +if @v@ is. +%************************************************************************ +%* * +\subsection[caf-info]{Collecting live CAF info} +%* * +%************************************************************************ + +In this pass we also collect information on which CAFs are live for +constructing SRTs (see SRT.lhs). + +A top-level Id has CafInfo, which is + + - MayHaveCafRefs, if it may refer indirectly to + one or more CAFs, or + - NoCafRefs if it definitely doesn't + +The CafInfo has already been calculated during the CoreTidy pass. -The business of this pass is to convert Core to Stg. On the way: +During CoreToStg, we then pin onto each binding and case expression, a +list of Ids which represents the "live" CAFs at that point. The meaning +of "live" here is the same as for live variables, see above (which is +why it's convenient to collect CAF information here rather than elsewhere). -* We discard type lambdas and applications. In so doing we discard - "trivial" bindings such as - x = y t1 t2 - where t1, t2 are types +The later SRT pass takes these lists of Ids and uses them to construct +the actual nested SRTs, and replaces the lists of Ids with (offset,length) +pairs. -* We don't pin on correct arities any more, because they can be mucked up - by the lambda lifter. In particular, the lambda lifter can take a local - letrec-bound variable and make it a lambda argument, which shouldn't have - an arity. So SetStgVarInfo sets arities now. -* We do *not* pin on the correct free/live var info; that's done later. - Instead we use bOGUS_LVS and _FVS as a placeholder. +Interaction of let-no-escape with SRTs [Sept 01] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider -[Quite a bit of stuff that used to be here has moved - to tidyCorePgm (SimplCore.lhs) SLPJ Nov 96] + let-no-escape x = ...caf1...caf2... + in + ...x...x...x... + +where caf1,caf2 are CAFs. Since x doesn't have a closure, we +build SRTs just as if x's defn was inlined at each call site, and +that means that x's CAF refs get duplicated in the overall SRT. + +This is unlike ordinary lets, in which the CAF refs are not duplicated. + +We could fix this loss of (static) sharing by making a sort of pseudo-closure +for x, solely to put in the SRTs lower down. %************************************************************************ %* * -\subsection[coreToStg-programs]{Converting a core program and core bindings} +\subsection[binds-StgVarInfo]{Setting variable info: top-level, binds, RHSs} %* * %************************************************************************ -Because we're going to come across ``boring'' bindings like -\tr{let x = /\ tyvars -> y in ...}, we want to keep a small -environment, so we can just replace all occurrences of \tr{x} -with \tr{y}. +\begin{code} +coreToStg :: HomeModules -> [CoreBind] -> IO [StgBinding] +coreToStg hmods pgm + = return pgm' + where (_, _, pgm') = coreTopBindsToStg hmods emptyVarEnv pgm -March 98: We also use this environment to give all locally bound -Names new unique ids, since the code generator assumes that binders -are unique across a module. (Simplifier doesn't maintain this -invariant any longer.) +coreExprToStg :: CoreExpr -> StgExpr +coreExprToStg expr + = new_expr where (new_expr,_,_) = initLne emptyVarEnv (coreToStgExpr expr) -\begin{code} -type StgEnv = IdEnv StgArg -\end{code} -No free/live variable information is pinned on in this pass; it's added -later. For this pass -we use @bOGUS_LVs@ and @bOGUS_FVs@ as placeholders. +coreTopBindsToStg + :: HomeModules + -> IdEnv HowBound -- environment for the bindings + -> [CoreBind] + -> (IdEnv HowBound, FreeVarsInfo, [StgBinding]) -\begin{code} -bOGUS_LVs :: StgLiveVars -bOGUS_LVs = panic "bOGUS_LVs" -- emptyUniqSet (used when pprTracing) +coreTopBindsToStg hmods env [] = (env, emptyFVInfo, []) +coreTopBindsToStg hmods env (b:bs) + = (env2, fvs2, b':bs') + where + -- env accumulates down the list of binds, fvs accumulates upwards + (env1, fvs2, b' ) = coreTopBindToStg hmods env fvs1 b + (env2, fvs1, bs') = coreTopBindsToStg hmods env1 bs + + +coreTopBindToStg + :: HomeModules + -> IdEnv HowBound + -> FreeVarsInfo -- Info about the body + -> CoreBind + -> (IdEnv HowBound, FreeVarsInfo, StgBinding) + +coreTopBindToStg hmods env body_fvs (NonRec id rhs) + = let + env' = extendVarEnv env id how_bound + how_bound = LetBound TopLet $! manifestArity rhs + + (stg_rhs, fvs') = + initLne env ( + coreToTopStgRhs hmods body_fvs (id,rhs) `thenLne` \ (stg_rhs, fvs') -> + returnLne (stg_rhs, fvs') + ) + + bind = StgNonRec id stg_rhs + in + ASSERT2(manifestArity rhs == stgRhsArity stg_rhs, ppr id) + ASSERT2(consistentCafInfo id bind, ppr id) +-- WARN(not (consistent caf_info bind), ppr id <+> ppr cafs <+> ppCafInfo caf_info) + (env', fvs' `unionFVInfo` body_fvs, bind) + +coreTopBindToStg hmods env body_fvs (Rec pairs) + = let + (binders, rhss) = unzip pairs -bOGUS_FVs :: [Id] -bOGUS_FVs = panic "bOGUS_FVs" -- [] (ditto) + extra_env' = [ (b, LetBound TopLet $! manifestArity rhs) + | (b, rhs) <- pairs ] + env' = extendVarEnvList env extra_env' + + (stg_rhss, fvs') + = initLne env' ( + mapAndUnzipLne (coreToTopStgRhs hmods body_fvs) pairs + `thenLne` \ (stg_rhss, fvss') -> + let fvs' = unionFVInfos fvss' in + returnLne (stg_rhss, fvs') + ) + + bind = StgRec (zip binders stg_rhss) + in + ASSERT2(and [manifestArity rhs == stgRhsArity stg_rhs | (rhs,stg_rhs) <- rhss `zip` stg_rhss], ppr binders) + ASSERT2(consistentCafInfo (head binders) bind, ppr binders) + (env', fvs' `unionFVInfo` body_fvs, bind) + +#ifdef DEBUG +-- Assertion helper: this checks that the CafInfo on the Id matches +-- what CoreToStg has figured out about the binding's SRT. The +-- CafInfo will be exact in all cases except when CorePrep has +-- floated out a binding, in which case it will be approximate. +consistentCafInfo id bind + | occNameFS (nameOccName (idName id)) == FSLIT("sat") + = safe + | otherwise + = WARN (not exact, ppr id) safe + where + safe = id_marked_caffy || not binding_is_caffy + exact = id_marked_caffy == binding_is_caffy + id_marked_caffy = mayHaveCafRefs (idCafInfo id) + binding_is_caffy = stgBindHasCafRefs bind +#endif \end{code} \begin{code} -topCoreBindsToStg :: UniqSupply -- name supply - -> [CoreBinding] -- input - -> [StgBinding] -- output - -topCoreBindsToStg us core_binds - = initUs us (coreBindsToStg nullIdEnv core_binds) +coreToTopStgRhs + :: HomeModules + -> FreeVarsInfo -- Free var info for the scope of the binding + -> (Id,CoreExpr) + -> LneM (StgRhs, FreeVarsInfo) + +coreToTopStgRhs hmods scope_fv_info (bndr, rhs) + = coreToStgExpr rhs `thenLne` \ (new_rhs, rhs_fvs, _) -> + freeVarsToLiveVars rhs_fvs `thenLne` \ lv_info -> + returnLne (mkTopStgRhs is_static rhs_fvs (mkSRT lv_info) bndr_info new_rhs, rhs_fvs) where - coreBindsToStg :: StgEnv -> [CoreBinding] -> UniqSM [StgBinding] + bndr_info = lookupFVInfo scope_fv_info bndr + is_static = rhsIsStatic hmods rhs + +mkTopStgRhs :: Bool -> FreeVarsInfo -> SRT -> StgBinderInfo -> StgExpr + -> StgRhs + +mkTopStgRhs is_static rhs_fvs srt binder_info (StgLam _ bndrs body) + = ASSERT( is_static ) + StgRhsClosure noCCS binder_info + (getFVs rhs_fvs) + ReEntrant + srt + bndrs body + +mkTopStgRhs is_static rhs_fvs srt binder_info (StgConApp con args) + | is_static -- StgConApps can be updatable (see isCrossDllConApp) + = StgRhsCon noCCS con args + +mkTopStgRhs is_static rhs_fvs srt binder_info rhs + = ASSERT2( not is_static, ppr rhs ) + StgRhsClosure noCCS binder_info + (getFVs rhs_fvs) + Updatable + srt + [] rhs +\end{code} + + +-- --------------------------------------------------------------------------- +-- Expressions +-- --------------------------------------------------------------------------- - coreBindsToStg env [] = returnUs [] - coreBindsToStg env (b:bs) - = coreBindToStg env b `thenUs` \ (new_b, new_env) -> - coreBindsToStg new_env bs `thenUs` \ new_bs -> - returnUs (new_b ++ new_bs) +\begin{code} +coreToStgExpr + :: CoreExpr + -> LneM (StgExpr, -- Decorated STG expr + FreeVarsInfo, -- Its free vars (NB free, not live) + EscVarsSet) -- Its escapees, a subset of its free vars; + -- also a subset of the domain of the envt + -- because we are only interested in the escapees + -- for vars which might be turned into + -- let-no-escaped ones. \end{code} -%************************************************************************ -%* * -\subsection[coreToStg-binds]{Converting bindings} -%* * -%************************************************************************ +The second and third components can be derived in a simple bottom up pass, not +dependent on any decisions about which variables will be let-no-escaped or +not. The first component, that is, the decorated expression, may then depend +on these components, but it in turn is not scrutinised as the basis for any +decisions. Hence no black holes. \begin{code} -coreBindToStg :: StgEnv - -> CoreBinding - -> UniqSM ([StgBinding], -- Empty or singleton - StgEnv) -- Floats +coreToStgExpr (Lit l) = returnLne (StgLit l, emptyFVInfo, emptyVarSet) +coreToStgExpr (Var v) = coreToStgApp Nothing v [] + +coreToStgExpr expr@(App _ _) + = coreToStgApp Nothing f args + where + (f, args) = myCollectArgs expr -coreBindToStg env (NonRec binder rhs) - = coreRhsToStg env rhs `thenUs` \ stg_rhs -> +coreToStgExpr expr@(Lam _ _) + = let + (args, body) = myCollectBinders expr + args' = filterStgBinders args + in + extendVarEnvLne [ (a, LambdaBound) | a <- args' ] $ + coreToStgExpr body `thenLne` \ (body, body_fvs, body_escs) -> let - -- Binds to return if RHS is trivial - triv_binds | externallyVisibleId binder = [StgNonRec binder stg_rhs] -- Retain it - | otherwise = [] -- Discard it + fvs = args' `minusFVBinders` body_fvs + escs = body_escs `delVarSetList` args' + result_expr | null args' = body + | otherwise = StgLam (exprType expr) args' body in - case stg_rhs of - StgRhsClosure cc bi fvs upd [] (StgApp atom [] lvs) -> - -- Trivial RHS, so augment envt, and ditch the binding - returnUs (triv_binds, new_env) - where - new_env = addOneToIdEnv env binder atom - - StgRhsCon cc con_id [] -> - -- Trivial RHS, so augment envt, and ditch the binding - returnUs (triv_binds, new_env) - where - new_env = addOneToIdEnv env binder (StgConArg con_id) - - other -> -- Non-trivial RHS - mkUniqueBinder env binder `thenUs` \ (new_env, new_binder) -> - returnUs ([StgNonRec new_binder stg_rhs], new_env) - where - mkUniqueBinder env binder - | externallyVisibleId binder = returnUs (env, binder) - | otherwise = - -- local binder, give it a new unique Id. - newUniqueLocalId binder `thenUs` \ binder' -> - let - new_env = addOneToIdEnv env binder (StgVarArg binder') - in - returnUs (new_env, binder') - - -coreBindToStg env (Rec pairs) - = -- NB: *** WE DO NOT CHECK FOR TRIV_BINDS in REC BIND **** - -- (possibly ToDo) + returnLne (result_expr, fvs, escs) + +coreToStgExpr (Note (SCC cc) expr) + = coreToStgExpr expr `thenLne` ( \ (expr2, fvs, escs) -> + returnLne (StgSCC cc expr2, fvs, escs) ) + +#ifdef ILX +-- For ILX, convert (__coerce__ to_ty from_ty e) +-- into (coerce to_ty from_ty e) +-- where coerce is real function +coreToStgExpr (Note (Coerce to_ty from_ty) expr) + = coreToStgExpr (mkApps (Var unsafeCoerceId) + [Type from_ty, Type to_ty, expr]) +#endif + +coreToStgExpr (Note other_note expr) + = coreToStgExpr expr + +-- Cases require a little more real work. + +coreToStgExpr (Case scrut bndr _ alts) + = extendVarEnvLne [(bndr, LambdaBound)] ( + mapAndUnzip3Lne vars_alt alts `thenLne` \ (alts2, fvs_s, escs_s) -> + returnLne ( alts2, + unionFVInfos fvs_s, + unionVarSets escs_s ) + ) `thenLne` \ (alts2, alts_fvs, alts_escs) -> let - (binders, rhss) = unzip pairs + -- Determine whether the default binder is dead or not + -- This helps the code generator to avoid generating an assignment + -- for the case binder (is extremely rare cases) ToDo: remove. + bndr' | bndr `elementOfFVInfo` alts_fvs = bndr + | otherwise = bndr `setIdOccInfo` IAmDead + + -- Don't consider the default binder as being 'live in alts', + -- since this is from the point of view of the case expr, where + -- the default binder is not free. + alts_fvs_wo_bndr = bndr `minusFVBinder` alts_fvs + alts_escs_wo_bndr = alts_escs `delVarSet` bndr in - newLocalIds env True{-maybe externally visible-} binders `thenUs` \ (binders', env') -> - mapUs (coreRhsToStg env') rhss `thenUs` \ stg_rhss -> - returnUs ([StgRec (binders' `zip` stg_rhss)], env') + + freeVarsToLiveVars alts_fvs_wo_bndr `thenLne` \ alts_lv_info -> + + -- We tell the scrutinee that everything + -- live in the alts is live in it, too. + setVarsLiveInCont alts_lv_info ( + coreToStgExpr scrut `thenLne` \ (scrut2, scrut_fvs, scrut_escs) -> + freeVarsToLiveVars scrut_fvs `thenLne` \ scrut_lv_info -> + returnLne (scrut2, scrut_fvs, scrut_escs, scrut_lv_info) + ) + `thenLne` \ (scrut2, scrut_fvs, scrut_escs, scrut_lv_info) -> + + returnLne ( + StgCase scrut2 (getLiveVars scrut_lv_info) + (getLiveVars alts_lv_info) + bndr' + (mkSRT alts_lv_info) + (mkStgAltType (idType bndr) alts) + alts2, + scrut_fvs `unionFVInfo` alts_fvs_wo_bndr, + alts_escs_wo_bndr `unionVarSet` getFVSet scrut_fvs + -- You might think we should have scrut_escs, not + -- (getFVSet scrut_fvs), but actually we can't call, and + -- then return from, a let-no-escape thing. + ) + where + vars_alt (con, binders, rhs) + = let -- Remove type variables + binders' = filterStgBinders binders + in + extendVarEnvLne [(b, LambdaBound) | b <- binders'] $ + coreToStgExpr rhs `thenLne` \ (rhs2, rhs_fvs, rhs_escs) -> + let + -- Records whether each param is used in the RHS + good_use_mask = [ b `elementOfFVInfo` rhs_fvs | b <- binders' ] + in + returnLne ( (con, binders', good_use_mask, rhs2), + binders' `minusFVBinders` rhs_fvs, + rhs_escs `delVarSetList` binders' ) + -- ToDo: remove the delVarSet; + -- since escs won't include any of these binders \end{code} +Lets not only take quite a bit of work, but this is where we convert +then to let-no-escapes, if we wish. -%************************************************************************ -%* * -\subsection[coreToStg-rhss]{Converting right hand sides} -%* * -%************************************************************************ - +(Meanwhile, we don't expect to see let-no-escapes...) \begin{code} -coreRhsToStg :: StgEnv -> CoreExpr -> UniqSM StgRhs - -coreRhsToStg env core_rhs - = coreExprToStg env core_rhs `thenUs` \ stg_expr -> - - let stg_rhs = case stg_expr of - StgLet (StgNonRec var1 rhs) (StgApp (StgVarArg var2) [] _) - | var1 == var2 -> rhs - -- This curious stuff is to unravel what a lambda turns into - -- We have to do it this way, rather than spot a lambda in the - -- incoming rhs. Why? Because trivial bindings might conceal - -- what the rhs is actually like. - - StgCon con args _ -> StgRhsCon noCostCentre con args - - other -> StgRhsClosure noCostCentre -- No cost centre (ToDo?) - stgArgOcc -- safe - bOGUS_FVs - Updatable -- Be pessimistic - [] - stg_expr - in - returnUs stg_rhs -\end{code} - +coreToStgExpr (Let bind body) + = fixLne (\ ~(_, _, _, no_binder_escapes) -> + coreToStgLet no_binder_escapes bind body + ) `thenLne` \ (new_let, fvs, escs, _) -> -%************************************************************************ -%* * -\subsection[coreToStg-atoms{Converting atoms} -%* * -%************************************************************************ + returnLne (new_let, fvs, escs) +\end{code} \begin{code} -coreArgsToStg :: StgEnv -> [CoreArg] -> ([Type], [StgArg]) - -coreArgsToStg env [] = ([], []) -coreArgsToStg env (a:as) - = case a of - TyArg t -> (t:trest, vrest) - VarArg v -> (trest, stgLookup env v : vrest) - LitArg l -> (trest, StgLitArg l : vrest) +mkStgAltType scrut_ty alts + = case splitTyConApp_maybe (repType scrut_ty) of + Just (tc,_) | isUnboxedTupleTyCon tc -> UbxTupAlt tc + | isPrimTyCon tc -> PrimAlt tc + | isHiBootTyCon tc -> look_for_better_tycon + | isAlgTyCon tc -> AlgAlt tc + | isFunTyCon tc -> PolyAlt + | otherwise -> pprPanic "mkStgAlts" (ppr tc) + Nothing -> PolyAlt + where - (trest,vrest) = coreArgsToStg env as + -- Sometimes, the TyCon in the type of the scrutinee is an HiBootTyCon, + -- which may not have any constructors inside it. If so, then we + -- can get a better TyCon by grabbing the one from a constructor alternative + -- if one exists. + look_for_better_tycon + | ((DataAlt con, _, _) : _) <- data_alts = + AlgAlt (dataConTyCon con) + | otherwise = + ASSERT(null data_alts) + PolyAlt + where + (data_alts, _deflt) = findDefault alts \end{code} -%************************************************************************ -%* * -\subsection[coreToStg-exprs]{Converting core expressions} -%* * -%************************************************************************ +-- --------------------------------------------------------------------------- +-- Applications +-- --------------------------------------------------------------------------- \begin{code} -coreExprToStg :: StgEnv -> CoreExpr -> UniqSM StgExpr - -coreExprToStg env (Lit lit) - = returnUs (StgApp (StgLitArg lit) [] bOGUS_LVs) +coreToStgApp + :: Maybe UpdateFlag -- Just upd <=> this application is + -- the rhs of a thunk binding + -- x = [...] \upd [] -> the_app + -- with specified update flag + -> Id -- Function + -> [CoreArg] -- Arguments + -> LneM (StgExpr, FreeVarsInfo, EscVarsSet) + +coreToStgApp maybe_thunk_body f args + = coreToStgArgs args `thenLne` \ (args', args_fvs) -> + lookupVarLne f `thenLne` \ how_bound -> -coreExprToStg env (Var var) - = returnUs (mk_app (stgLookup env var) []) + let + n_val_args = valArgCount args + not_letrec_bound = not (isLetBound how_bound) + fun_fvs + = let fvs = singletonFVInfo f how_bound fun_occ in + -- e.g. (f :: a -> int) (x :: a) + -- Here the free variables are "f", "x" AND the type variable "a" + -- coreToStgArgs will deal with the arguments recursively + if opt_RuntimeTypes then + fvs `unionFVInfo` tyvarFVInfo (tyVarsOfType (idType f)) + else fvs + + -- Mostly, the arity info of a function is in the fn's IdInfo + -- But new bindings introduced by CoreSat may not have no + -- arity info; it would do us no good anyway. For example: + -- let f = \ab -> e in f + -- No point in having correct arity info for f! + -- Hence the hasArity stuff below. + -- NB: f_arity is only consulted for LetBound things + f_arity = stgArity f how_bound + saturated = f_arity <= n_val_args + + fun_occ + | not_letrec_bound = noBinderInfo -- Uninteresting variable + | f_arity > 0 && saturated = stgSatOcc -- Saturated or over-saturated function call + | otherwise = stgUnsatOcc -- Unsaturated function or thunk + + fun_escs + | not_letrec_bound = emptyVarSet -- Only letrec-bound escapees are interesting + | f_arity == n_val_args = emptyVarSet -- A function *or thunk* with an exactly + -- saturated call doesn't escape + -- (let-no-escape applies to 'thunks' too) + + | otherwise = unitVarSet f -- Inexact application; it does escape + + -- At the moment of the call: + + -- either the function is *not* let-no-escaped, in which case + -- nothing is live except live_in_cont + -- or the function *is* let-no-escaped in which case the + -- variables it uses are live, but still the function + -- itself is not. PS. In this case, the function's + -- live vars should already include those of the + -- continuation, but it does no harm to just union the + -- two regardless. + + res_ty = exprType (mkApps (Var f) args) + app = case globalIdDetails f of + DataConWorkId dc | saturated -> StgConApp dc args' + PrimOpId op -> ASSERT( saturated ) + StgOpApp (StgPrimOp op) args' res_ty + FCallId call -> ASSERT( saturated ) + StgOpApp (StgFCallOp call (idUnique f)) args' res_ty + _other -> StgApp f args' -coreExprToStg env (Con con args) - = let - (types, stg_atoms) = coreArgsToStg env args in - returnUs (StgCon con stg_atoms bOGUS_LVs) + returnLne ( + app, + fun_fvs `unionFVInfo` args_fvs, + fun_escs `unionVarSet` (getFVSet args_fvs) + -- All the free vars of the args are disqualified + -- from being let-no-escaped. + ) -coreExprToStg env (Prim op args) - = let - (types, stg_atoms) = coreArgsToStg env args - in - returnUs (StgPrim op stg_atoms bOGUS_LVs) -\end{code} -%************************************************************************ -%* * -\subsubsection[coreToStg-lambdas]{Lambda abstractions} -%* * -%************************************************************************ -\begin{code} -coreExprToStg env expr@(Lam _ _) - = let - (_, binders, body) = collectBinders expr - in - newLocalIds env False{-all local-} binders `thenUs` \ (binders', env') -> - coreExprToStg env' body `thenUs` \ stg_body -> +-- --------------------------------------------------------------------------- +-- Argument lists +-- This is the guy that turns applications into A-normal form +-- --------------------------------------------------------------------------- + +coreToStgArgs :: [CoreArg] -> LneM ([StgArg], FreeVarsInfo) +coreToStgArgs [] + = returnLne ([], emptyFVInfo) - if null binders then -- it was all type/usage binders; tossed - returnUs stg_body +coreToStgArgs (Type ty : args) -- Type argument + = coreToStgArgs args `thenLne` \ (args', fvs) -> + if opt_RuntimeTypes then + returnLne (StgTypeArg ty : args', fvs `unionFVInfo` tyvarFVInfo (tyVarsOfType ty)) else - newStgVar (coreExprType expr) `thenUs` \ var -> - returnUs - (StgLet (StgNonRec var - (StgRhsClosure noCostCentre - stgArgOcc - bOGUS_FVs - ReEntrant -- binders is non-empty - binders' - stg_body)) - (StgApp (StgVarArg var) [] bOGUS_LVs)) -\end{code} + returnLne (args', fvs) -%************************************************************************ -%* * -\subsubsection[coreToStg-applications]{Applications} -%* * -%************************************************************************ +coreToStgArgs (arg : args) -- Non-type argument + = coreToStgArgs args `thenLne` \ (stg_args, args_fvs) -> + coreToStgExpr arg `thenLne` \ (arg', arg_fvs, escs) -> + let + fvs = args_fvs `unionFVInfo` arg_fvs + stg_arg = case arg' of + StgApp v [] -> StgVarArg v + StgConApp con [] -> StgVarArg (dataConWorkId con) + StgLit lit -> StgLitArg lit + _ -> pprPanic "coreToStgArgs" (ppr arg) + in + returnLne (stg_arg : stg_args, fvs) -\begin{code} -coreExprToStg env expr@(App _ _) - = let - (fun,args) = collect_args expr [] - (_, stg_args) = coreArgsToStg env args + +-- --------------------------------------------------------------------------- +-- The magic for lets: +-- --------------------------------------------------------------------------- + +coreToStgLet + :: Bool -- True <=> yes, we are let-no-escaping this let + -> CoreBind -- bindings + -> CoreExpr -- body + -> LneM (StgExpr, -- new let + FreeVarsInfo, -- variables free in the whole let + EscVarsSet, -- variables that escape from the whole let + Bool) -- True <=> none of the binders in the bindings + -- is among the escaping vars + +coreToStgLet let_no_escape bind body + = fixLne (\ ~(_, _, _, _, _, rec_body_fvs, _, _) -> + + -- Do the bindings, setting live_in_cont to empty if + -- we ain't in a let-no-escape world + getVarsLiveInCont `thenLne` \ live_in_cont -> + setVarsLiveInCont (if let_no_escape + then live_in_cont + else emptyLiveInfo) + (vars_bind rec_body_fvs bind) + `thenLne` \ ( bind2, bind_fvs, bind_escs, bind_lv_info, env_ext) -> + + -- Do the body + extendVarEnvLne env_ext ( + coreToStgExpr body `thenLne` \(body2, body_fvs, body_escs) -> + freeVarsToLiveVars body_fvs `thenLne` \ body_lv_info -> + + returnLne (bind2, bind_fvs, bind_escs, getLiveVars bind_lv_info, + body2, body_fvs, body_escs, getLiveVars body_lv_info) + ) + + ) `thenLne` (\ (bind2, bind_fvs, bind_escs, bind_lvs, + body2, body_fvs, body_escs, body_lvs) -> + + + -- Compute the new let-expression + let + new_let | let_no_escape = StgLetNoEscape live_in_whole_let bind_lvs bind2 body2 + | otherwise = StgLet bind2 body2 + + free_in_whole_let + = binders `minusFVBinders` (bind_fvs `unionFVInfo` body_fvs) + + live_in_whole_let + = bind_lvs `unionVarSet` (body_lvs `delVarSetList` binders) + + real_bind_escs = if let_no_escape then + bind_escs + else + getFVSet bind_fvs + -- Everything escapes which is free in the bindings + + let_escs = (real_bind_escs `unionVarSet` body_escs) `delVarSetList` binders + + all_escs = bind_escs `unionVarSet` body_escs -- Still includes binders of + -- this let(rec) + + no_binder_escapes = isEmptyVarSet (set_of_binders `intersectVarSet` all_escs) + +#ifdef DEBUG + -- Debugging code as requested by Andrew Kennedy + checked_no_binder_escapes + | not no_binder_escapes && any is_join_var binders + = pprTrace "Interesting! A join var that isn't let-no-escaped" (ppr binders) + False + | otherwise = no_binder_escapes +#else + checked_no_binder_escapes = no_binder_escapes +#endif + + -- Mustn't depend on the passed-in let_no_escape flag, since + -- no_binder_escapes is used by the caller to derive the flag! in - -- Now deal with the function - case (fun, args) of - (Var fun_id, _) -> -- A function Id, so do an StgApp; it's ok if - -- there are no arguments. - returnUs (mk_app (stgLookup env fun_id) stg_args) - - (non_var_fun, []) -> -- No value args, so recurse into the function - coreExprToStg env non_var_fun - - other -> -- A non-variable applied to things; better let-bind it. - newStgVar (coreExprType fun) `thenUs` \ fun_id -> - coreExprToStg env fun `thenUs` \ (stg_fun) -> - let - fun_rhs = StgRhsClosure noCostCentre -- No cost centre (ToDo?) - stgArgOcc - bOGUS_FVs - SingleEntry -- Only entered once - [] - stg_fun - in - returnUs (StgLet (StgNonRec fun_id fun_rhs) - (StgApp (StgVarArg fun_id) stg_args bOGUS_LVs)) + returnLne ( + new_let, + free_in_whole_let, + let_escs, + checked_no_binder_escapes + )) where - -- Collect arguments, discarding type/usage applications - collect_args (App e (TyArg _)) args = collect_args e args - collect_args (App fun arg) args = collect_args fun (arg:args) - collect_args (Coerce _ _ expr) args = collect_args expr args - collect_args fun args = (fun, args) + set_of_binders = mkVarSet binders + binders = bindersOf bind + + mk_binding bind_lv_info binder rhs + = (binder, LetBound (NestedLet live_vars) (manifestArity rhs)) + where + live_vars | let_no_escape = addLiveVar bind_lv_info binder + | otherwise = unitLiveVar binder + -- c.f. the invariant on NestedLet + + vars_bind :: FreeVarsInfo -- Free var info for body of binding + -> CoreBind + -> LneM (StgBinding, + FreeVarsInfo, + EscVarsSet, -- free vars; escapee vars + LiveInfo, -- Vars and CAFs live in binding + [(Id, HowBound)]) -- extension to environment + + + vars_bind body_fvs (NonRec binder rhs) + = coreToStgRhs body_fvs [] (binder,rhs) + `thenLne` \ (rhs2, bind_fvs, bind_lv_info, escs) -> + let + env_ext_item = mk_binding bind_lv_info binder rhs + in + returnLne (StgNonRec binder rhs2, + bind_fvs, escs, bind_lv_info, [env_ext_item]) + + + vars_bind body_fvs (Rec pairs) + = fixLne (\ ~(_, rec_rhs_fvs, _, bind_lv_info, _) -> + let + rec_scope_fvs = unionFVInfo body_fvs rec_rhs_fvs + binders = map fst pairs + env_ext = [ mk_binding bind_lv_info b rhs + | (b,rhs) <- pairs ] + in + extendVarEnvLne env_ext ( + mapAndUnzip4Lne (coreToStgRhs rec_scope_fvs binders) pairs + `thenLne` \ (rhss2, fvss, lv_infos, escss) -> + let + bind_fvs = unionFVInfos fvss + bind_lv_info = foldr unionLiveInfo emptyLiveInfo lv_infos + escs = unionVarSets escss + in + returnLne (StgRec (binders `zip` rhss2), + bind_fvs, escs, bind_lv_info, env_ext) + ) + ) + +is_join_var :: Id -> Bool +-- A hack (used only for compiler debuggging) to tell if +-- a variable started life as a join point ($j) +is_join_var j = occNameString (getOccName j) == "$j" \end{code} -%************************************************************************ -%* * -\subsubsection[coreToStg-cases]{Case expressions} -%* * -%************************************************************************ - \begin{code} -coreExprToStg env (Case discrim alts) - = coreExprToStg env discrim `thenUs` \ stg_discrim -> - alts_to_stg discrim alts `thenUs` \ stg_alts -> - getUnique `thenUs` \ uniq -> - returnUs ( - StgCase stg_discrim - bOGUS_LVs - bOGUS_LVs - uniq - stg_alts - ) +coreToStgRhs :: FreeVarsInfo -- Free var info for the scope of the binding + -> [Id] + -> (Id,CoreExpr) + -> LneM (StgRhs, FreeVarsInfo, LiveInfo, EscVarsSet) + +coreToStgRhs scope_fv_info binders (bndr, rhs) + = coreToStgExpr rhs `thenLne` \ (new_rhs, rhs_fvs, rhs_escs) -> + getEnvLne `thenLne` \ env -> + freeVarsToLiveVars (binders `minusFVBinders` rhs_fvs) `thenLne` \ lv_info -> + returnLne (mkStgRhs rhs_fvs (mkSRT lv_info) bndr_info new_rhs, + rhs_fvs, lv_info, rhs_escs) + where + bndr_info = lookupFVInfo scope_fv_info bndr + +mkStgRhs :: FreeVarsInfo -> SRT -> StgBinderInfo -> StgExpr -> StgRhs + +mkStgRhs rhs_fvs srt binder_info (StgConApp con args) + = StgRhsCon noCCS con args + +mkStgRhs rhs_fvs srt binder_info (StgLam _ bndrs body) + = StgRhsClosure noCCS binder_info + (getFVs rhs_fvs) + ReEntrant + srt bndrs body + +mkStgRhs rhs_fvs srt binder_info rhs + = StgRhsClosure noCCS binder_info + (getFVs rhs_fvs) + upd_flag srt [] rhs where - discrim_ty = coreExprType discrim - (_, discrim_ty_args, _) = splitAlgTyConApp discrim_ty - - alts_to_stg discrim (AlgAlts alts deflt) - = default_to_stg discrim deflt `thenUs` \ stg_deflt -> - mapUs boxed_alt_to_stg alts `thenUs` \ stg_alts -> - returnUs (StgAlgAlts discrim_ty stg_alts stg_deflt) - where - boxed_alt_to_stg (con, bs, rhs) - = coreExprToStg env rhs `thenUs` \ stg_rhs -> - returnUs (con, bs, [ True | b <- bs ]{-bogus use mask-}, stg_rhs) - - alts_to_stg discrim (PrimAlts alts deflt) - = default_to_stg discrim deflt `thenUs` \ stg_deflt -> - mapUs unboxed_alt_to_stg alts `thenUs` \ stg_alts -> - returnUs (StgPrimAlts discrim_ty stg_alts stg_deflt) - where - unboxed_alt_to_stg (lit, rhs) - = coreExprToStg env rhs `thenUs` \ stg_rhs -> - returnUs (lit, stg_rhs) - - default_to_stg discrim NoDefault - = returnUs StgNoDefault - - default_to_stg discrim (BindDefault binder rhs) - = coreExprToStg env rhs `thenUs` \ stg_rhs -> - returnUs (StgBindDefault binder True{-used? no it is lying-} stg_rhs) + upd_flag = Updatable + {- + SDM: disabled. Eval/Apply can't handle functions with arity zero very + well; and making these into simple non-updatable thunks breaks other + assumptions (namely that they will be entered only once). + + upd_flag | isPAP env rhs = ReEntrant + | otherwise = Updatable + -} + +{- ToDo: + upd = if isOnceDem dem + then (if isNotTop toplev + then SingleEntry -- HA! Paydirt for "dem" + else +#ifdef DEBUG + trace "WARNING: SE CAFs unsupported, forcing UPD instead" $ +#endif + Updatable) + else Updatable + -- For now we forbid SingleEntry CAFs; they tickle the + -- ASSERT in rts/Storage.c line 215 at newCAF() re mut_link, + -- and I don't understand why. There's only one SE_CAF (well, + -- only one that tickled a great gaping bug in an earlier attempt + -- at ClosureInfo.getEntryConvention) in the whole of nofib, + -- specifically Main.lvl6 in spectral/cryptarithm2. + -- So no great loss. KSW 2000-07. +-} \end{code} +Detect thunks which will reduce immediately to PAPs, and make them +non-updatable. This has several advantages: + + - the non-updatable thunk behaves exactly like the PAP, + + - the thunk is more efficient to enter, because it is + specialised to the task. + + - we save one update frame, one stg_update_PAP, one update + and lots of PAP_enters. + + - in the case where the thunk is top-level, we save building + a black hole and futhermore the thunk isn't considered to + be a CAF any more, so it doesn't appear in any SRTs. + +We do it here, because the arity information is accurate, and we need +to do it before the SRT pass to save the SRT entries associated with +any top-level PAPs. + +isPAP env (StgApp f args) = listLengthCmp args arity == LT -- idArity f > length args + where + arity = stgArity f (lookupBinding env f) +isPAP env _ = False + + %************************************************************************ %* * -\subsubsection[coreToStg-let(rec)]{Let and letrec expressions} +\subsection[LNE-monad]{A little monad for this let-no-escaping pass} %* * %************************************************************************ +There's a lot of stuff to pass around, so we use this @LneM@ monad to +help. All the stuff here is only passed *down*. + \begin{code} -coreExprToStg env (Let bind body) - = coreBindToStg env bind `thenUs` \ (stg_binds, new_env) -> - coreExprToStg new_env body `thenUs` \ stg_body -> - returnUs (mkStgLets stg_binds stg_body) +type LneM a = IdEnv HowBound + -> LiveInfo -- Vars and CAFs live in continuation + -> a + +type LiveInfo = (StgLiveVars, -- Dynamic live variables; + -- i.e. ones with a nested (non-top-level) binding + CafSet) -- Static live variables; + -- i.e. top-level variables that are CAFs or refer to them + +type EscVarsSet = IdSet +type CafSet = IdSet + +data HowBound + = ImportBound -- Used only as a response to lookupBinding; never + -- exists in the range of the (IdEnv HowBound) + + | LetBound -- A let(rec) in this module + LetInfo -- Whether top level or nested + Arity -- Its arity (local Ids don't have arity info at this point) + + | LambdaBound -- Used for both lambda and case + +data LetInfo + = TopLet -- top level things + | NestedLet LiveInfo -- For nested things, what is live if this + -- thing is live? Invariant: the binder + -- itself is always a member of + -- the dynamic set of its own LiveInfo + +isLetBound (LetBound _ _) = True +isLetBound other = False + +topLevelBound ImportBound = True +topLevelBound (LetBound TopLet _) = True +topLevelBound other = False \end{code} +For a let(rec)-bound variable, x, we record LiveInfo, the set of +variables that are live if x is live. This LiveInfo comprises + (a) dynamic live variables (ones with a non-top-level binding) + (b) static live variabes (CAFs or things that refer to CAFs) -%************************************************************************ -%* * -\subsubsection[coreToStg-scc]{SCC expressions} -%* * -%************************************************************************ +For "normal" variables (a) is just x alone. If x is a let-no-escaped +variable then x is represented by a code pointer and a stack pointer +(well, one for each stack). So all of the variables needed in the +execution of x are live if x is, and are therefore recorded in the +LetBound constructor; x itself *is* included. + +The set of dynamic live variables is guaranteed ot have no further let-no-escaped +variables in it. -Covert core @scc@ expression directly to STG @scc@ expression. \begin{code} -coreExprToStg env (SCC cc expr) - = coreExprToStg env expr `thenUs` \ stg_expr -> - returnUs (StgSCC (coreExprType expr) cc stg_expr) +emptyLiveInfo :: LiveInfo +emptyLiveInfo = (emptyVarSet,emptyVarSet) + +unitLiveVar :: Id -> LiveInfo +unitLiveVar lv = (unitVarSet lv, emptyVarSet) + +unitLiveCaf :: Id -> LiveInfo +unitLiveCaf caf = (emptyVarSet, unitVarSet caf) + +addLiveVar :: LiveInfo -> Id -> LiveInfo +addLiveVar (lvs, cafs) id = (lvs `extendVarSet` id, cafs) + +unionLiveInfo :: LiveInfo -> LiveInfo -> LiveInfo +unionLiveInfo (lv1,caf1) (lv2,caf2) = (lv1 `unionVarSet` lv2, caf1 `unionVarSet` caf2) + +mkSRT :: LiveInfo -> SRT +mkSRT (_, cafs) = SRTEntries cafs + +getLiveVars :: LiveInfo -> StgLiveVars +getLiveVars (lvs, _) = lvs \end{code} + +The std monad functions: \begin{code} -coreExprToStg env (Coerce c ty expr) = coreExprToStg env expr +initLne :: IdEnv HowBound -> LneM a -> a +initLne env m = m env emptyLiveInfo + + + +{-# INLINE thenLne #-} +{-# INLINE returnLne #-} + +returnLne :: a -> LneM a +returnLne e env lvs_cont = e + +thenLne :: LneM a -> (a -> LneM b) -> LneM b +thenLne m k env lvs_cont + = k (m env lvs_cont) env lvs_cont + +mapAndUnzipLne :: (a -> LneM (b,c)) -> [a] -> LneM ([b],[c]) +mapAndUnzipLne f [] = returnLne ([],[]) +mapAndUnzipLne f (x:xs) + = f x `thenLne` \ (r1, r2) -> + mapAndUnzipLne f xs `thenLne` \ (rs1, rs2) -> + returnLne (r1:rs1, r2:rs2) + +mapAndUnzip3Lne :: (a -> LneM (b,c,d)) -> [a] -> LneM ([b],[c],[d]) +mapAndUnzip3Lne f [] = returnLne ([],[],[]) +mapAndUnzip3Lne f (x:xs) + = f x `thenLne` \ (r1, r2, r3) -> + mapAndUnzip3Lne f xs `thenLne` \ (rs1, rs2, rs3) -> + returnLne (r1:rs1, r2:rs2, r3:rs3) + +mapAndUnzip4Lne :: (a -> LneM (b,c,d,e)) -> [a] -> LneM ([b],[c],[d],[e]) +mapAndUnzip4Lne f [] = returnLne ([],[],[],[]) +mapAndUnzip4Lne f (x:xs) + = f x `thenLne` \ (r1, r2, r3, r4) -> + mapAndUnzip4Lne f xs `thenLne` \ (rs1, rs2, rs3, rs4) -> + returnLne (r1:rs1, r2:rs2, r3:rs3, r4:rs4) + +fixLne :: (a -> LneM a) -> LneM a +fixLne expr env lvs_cont + = result + where + result = expr result env lvs_cont \end{code} +Functions specific to this monad: + +\begin{code} +getVarsLiveInCont :: LneM LiveInfo +getVarsLiveInCont env lvs_cont = lvs_cont + +setVarsLiveInCont :: LiveInfo -> LneM a -> LneM a +setVarsLiveInCont new_lvs_cont expr env lvs_cont + = expr env new_lvs_cont + +extendVarEnvLne :: [(Id, HowBound)] -> LneM a -> LneM a +extendVarEnvLne ids_w_howbound expr env lvs_cont + = expr (extendVarEnvList env ids_w_howbound) lvs_cont + +lookupVarLne :: Id -> LneM HowBound +lookupVarLne v env lvs_cont = returnLne (lookupBinding env v) env lvs_cont + +getEnvLne :: LneM (IdEnv HowBound) +getEnvLne env lvs_cont = returnLne env env lvs_cont + +lookupBinding :: IdEnv HowBound -> Id -> HowBound +lookupBinding env v = case lookupVarEnv env v of + Just xx -> xx + Nothing -> ASSERT2( isGlobalId v, ppr v ) ImportBound + + +-- The result of lookupLiveVarsForSet, a set of live variables, is +-- only ever tacked onto a decorated expression. It is never used as +-- the basis of a control decision, which might give a black hole. + +freeVarsToLiveVars :: FreeVarsInfo -> LneM LiveInfo +freeVarsToLiveVars fvs env live_in_cont + = returnLne live_info env live_in_cont + where + live_info = foldr unionLiveInfo live_in_cont lvs_from_fvs + lvs_from_fvs = map do_one (allFreeIds fvs) + + do_one (v, how_bound) + = case how_bound of + ImportBound -> unitLiveCaf v -- Only CAF imports are + -- recorded in fvs + LetBound TopLet _ + | mayHaveCafRefs (idCafInfo v) -> unitLiveCaf v + | otherwise -> emptyLiveInfo + + LetBound (NestedLet lvs) _ -> lvs -- lvs already contains v + -- (see the invariant on NestedLet) + + _lambda_or_case_binding -> unitLiveVar v -- Bound by lambda or case +\end{code} %************************************************************************ %* * -\subsection[coreToStg-misc]{Miscellaneous helping functions} +\subsection[Free-var info]{Free variable information} %* * %************************************************************************ -There's not anything interesting we can ASSERT about \tr{var} if it -isn't in the StgEnv. (WDP 94/06) - \begin{code} -stgLookup :: StgEnv -> Id -> StgArg -stgLookup env var = case (lookupIdEnv env var) of - Nothing -> StgVarArg var - Just atom -> atom +type FreeVarsInfo = VarEnv (Var, HowBound, StgBinderInfo) + -- The Var is so we can gather up the free variables + -- as a set. + -- + -- The HowBound info just saves repeated lookups; + -- we look up just once when we encounter the occurrence. + -- INVARIANT: Any ImportBound Ids are HaveCafRef Ids + -- Imported Ids without CAF refs are simply + -- not put in the FreeVarsInfo for an expression. + -- See singletonFVInfo and freeVarsToLiveVars + -- + -- StgBinderInfo records how it occurs; notably, we + -- are interested in whether it only occurs in saturated + -- applications, because then we don't need to build a + -- curried version. + -- If f is mapped to noBinderInfo, that means + -- that f *is* mentioned (else it wouldn't be in the + -- IdEnv at all), but perhaps in an unsaturated applications. + -- + -- All case/lambda-bound things are also mapped to + -- noBinderInfo, since we aren't interested in their + -- occurence info. + -- + -- For ILX we track free var info for type variables too; + -- hence VarEnv not IdEnv \end{code} -Invent a fresh @Id@: \begin{code} -newStgVar :: Type -> UniqSM Id -newStgVar ty - = getUnique `thenUs` \ uniq -> - returnUs (mkSysLocal SLIT("stg") uniq ty noSrcLoc) +emptyFVInfo :: FreeVarsInfo +emptyFVInfo = emptyVarEnv + +singletonFVInfo :: Id -> HowBound -> StgBinderInfo -> FreeVarsInfo +-- Don't record non-CAF imports at all, to keep free-var sets small +singletonFVInfo id ImportBound info + | mayHaveCafRefs (idCafInfo id) = unitVarEnv id (id, ImportBound, info) + | otherwise = emptyVarEnv +singletonFVInfo id how_bound info = unitVarEnv id (id, how_bound, info) + +tyvarFVInfo :: TyVarSet -> FreeVarsInfo +tyvarFVInfo tvs = foldVarSet add emptyFVInfo tvs + where + add tv fvs = extendVarEnv fvs tv (tv, LambdaBound, noBinderInfo) + -- Type variables must be lambda-bound + +unionFVInfo :: FreeVarsInfo -> FreeVarsInfo -> FreeVarsInfo +unionFVInfo fv1 fv2 = plusVarEnv_C plusFVInfo fv1 fv2 + +unionFVInfos :: [FreeVarsInfo] -> FreeVarsInfo +unionFVInfos fvs = foldr unionFVInfo emptyFVInfo fvs + +minusFVBinders :: [Id] -> FreeVarsInfo -> FreeVarsInfo +minusFVBinders vs fv = foldr minusFVBinder fv vs + +minusFVBinder :: Id -> FreeVarsInfo -> FreeVarsInfo +minusFVBinder v fv | isId v && opt_RuntimeTypes + = (fv `delVarEnv` v) `unionFVInfo` + tyvarFVInfo (tyVarsOfType (idType v)) + | otherwise = fv `delVarEnv` v + -- When removing a binder, remember to add its type variables + -- c.f. CoreFVs.delBinderFV + +elementOfFVInfo :: Id -> FreeVarsInfo -> Bool +elementOfFVInfo id fvs = maybeToBool (lookupVarEnv fvs id) + +lookupFVInfo :: FreeVarsInfo -> Id -> StgBinderInfo +-- Find how the given Id is used. +-- Externally visible things may be used any old how +lookupFVInfo fvs id + | isExternalName (idName id) = noBinderInfo + | otherwise = case lookupVarEnv fvs id of + Nothing -> noBinderInfo + Just (_,_,info) -> info + +allFreeIds :: FreeVarsInfo -> [(Id,HowBound)] -- Both top level and non-top-level Ids +allFreeIds fvs = [(id,how_bound) | (id,how_bound,_) <- varEnvElts fvs, isId id] + +-- Non-top-level things only, both type variables and ids +-- (type variables only if opt_RuntimeTypes) +getFVs :: FreeVarsInfo -> [Var] +getFVs fvs = [id | (id, how_bound, _) <- varEnvElts fvs, + not (topLevelBound how_bound) ] + +getFVSet :: FreeVarsInfo -> VarSet +getFVSet fvs = mkVarSet (getFVs fvs) + +plusFVInfo (id1,hb1,info1) (id2,hb2,info2) + = ASSERT (id1 == id2 && hb1 `check_eq_how_bound` hb2) + (id1, hb1, combineStgBinderInfo info1 info2) + +#ifdef DEBUG +-- The HowBound info for a variable in the FVInfo should be consistent +check_eq_how_bound ImportBound ImportBound = True +check_eq_how_bound LambdaBound LambdaBound = True +check_eq_how_bound (LetBound li1 ar1) (LetBound li2 ar2) = ar1 == ar2 && check_eq_li li1 li2 +check_eq_how_bound hb1 hb2 = False + +check_eq_li (NestedLet _) (NestedLet _) = True +check_eq_li TopLet TopLet = True +check_eq_li li1 li2 = False +#endif \end{code} +Misc. \begin{code} -newUniqueLocalId :: Id -> UniqSM Id -newUniqueLocalId i = - getUnique `thenUs` \ uniq -> - returnUs (mkIdWithNewUniq i uniq) - -newLocalIds :: StgEnv -> Bool -> [Id] -> UniqSM ([Id], StgEnv) -newLocalIds env maybe_visible [] = returnUs ([], env) -newLocalIds env maybe_visible (i:is) - | maybe_visible && externallyVisibleId i = - newLocalIds env maybe_visible is `thenUs` \ (is', env') -> - returnUs (i:is', env') - | otherwise = - newUniqueLocalId i `thenUs` \ i' -> - let - new_env = addOneToIdEnv env i (StgVarArg i') - in - newLocalIds new_env maybe_visible is `thenUs` \ (is', env') -> - returnUs (i':is', env') +filterStgBinders :: [Var] -> [Var] +filterStgBinders bndrs + | opt_RuntimeTypes = bndrs + | otherwise = filter isId bndrs \end{code} \begin{code} -mkStgLets :: [StgBinding] - -> StgExpr -- body of let - -> StgExpr - -mkStgLets binds body = foldr StgLet body binds + -- Ignore all notes except SCC +myCollectBinders expr + = go [] expr + where + go bs (Lam b e) = go (b:bs) e + go bs e@(Note (SCC _) _) = (reverse bs, e) + go bs (Note _ e) = go bs e + go bs e = (reverse bs, e) + +myCollectArgs :: CoreExpr -> (Id, [CoreArg]) + -- We assume that we only have variables + -- in the function position by now +myCollectArgs expr + = go expr [] + where + go (Var v) as = (v, as) + go (App f a) as = go f (a:as) + go (Note (SCC _) e) as = pprPanic "CoreToStg.myCollectArgs" (ppr expr) + go (Note n e) as = go e as + go _ as = pprPanic "CoreToStg.myCollectArgs" (ppr expr) +\end{code} --- mk_app spots an StgCon in a function position, --- and turns it into an StgCon. See notes with --- getArgAmode in CgBindery. -mk_app (StgConArg con) args = StgCon con args bOGUS_LVs -mk_app other_fun args = StgApp other_fun args bOGUS_LVs +\begin{code} +stgArity :: Id -> HowBound -> Arity +stgArity f (LetBound _ arity) = arity +stgArity f ImportBound = idArity f +stgArity f LambdaBound = 0 \end{code}