%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
+% (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 CoreUtils ( exprType )
-import SimplUtils ( findDefault )
+import CoreSyn
+import CoreUtils ( rhsIsStatic, manifestArity, exprType )
+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 Id ( Id, mkSysLocal, idType, idStrictness, idUnique, isExportedId, mkVanillaId,
- externallyVisibleId, setIdUnique, idName,
- idDemandInfo, idArity, setIdType, idFlavour
- )
-import Var ( Var, varType, modifyIdInfo )
-import IdInfo ( setDemandInfo, StrictnessInfo(..), IdFlavour(..) )
-import UsageSPUtils ( primOpUsgTys )
-import DataCon ( DataCon, dataConName, isDynDataCon, dataConWrapId )
-import Demand ( Demand, isStrict, wwStrict, wwLazy )
-import Name ( Name, nameModule, isLocallyDefinedName, setNameUnique )
-import Module ( isDynamicModule )
-import Literal ( Literal(..) )
+import VarSet
import VarEnv
-import PrimOp ( PrimOp(..), CCall(..), CCallTarget(..), primOpUsg )
-import Type ( isUnLiftedType, isUnboxedTupleType, Type, splitFunTy_maybe,
- UsageAnn(..), tyUsg, applyTy, mkUsgTy, repType, seqType,
- splitRepFunTys, mkFunTys
- )
-import TysPrim ( intPrimTy )
-import UniqSupply -- all of it, really
-import Util ( lengthExceeds )
-import BasicTypes ( TopLevelFlag(..), isNotTopLevel, Arity )
-import CmdLineOpts ( opt_D_verbose_stg2stg, opt_UsageSPOn )
-import UniqSet ( emptyUniqSet )
-import Maybes
+import Maybes ( maybeToBool )
+import Name ( getOccName, isExternalName, nameOccName )
+import OccName ( occNameUserString, occNameFS )
+import BasicTypes ( Arity )
+import CmdLineOpts ( DynFlags, opt_RuntimeTypes )
import Outputable
+
+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}
+%* *
+%************************************************************************
-The business of this pass is to convert Core to Stg. On the way it
-does some important transformations:
+In this pass we also collect information on which CAFs are live for
+constructing SRTs (see SRT.lhs).
-1. We discard type lambdas and applications. In so doing we discard
- "trivial" bindings such as
- x = y t1 t2
- where t1, t2 are types
+A top-level Id has CafInfo, which is
-2. We get the program into "A-normal form". In particular:
+ - MayHaveCafRefs, if it may refer indirectly to
+ one or more CAFs, or
+ - NoCafRefs if it definitely doesn't
- f E ==> let x = E in f x
- OR ==> case E of x -> f x
+The CafInfo has already been calculated during the CoreTidy pass.
- where E is a non-trivial expression.
- Which transformation is used depends on whether f is strict or not.
- [Previously the transformation to case used to be done by the
- simplifier, but it's better done here. It does mean that f needs
- to have its strictness info correct!.]
+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).
- Similarly, convert any unboxed let's into cases.
- [I'm experimenting with leaving 'ok-for-speculation' rhss in let-form
- right up to this point.]
+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.
-3. We clone all local binders. The code generator uses the uniques to
- name chunks of code for thunks, so it's important that the names used
- are globally unique, not simply not-in-scope, which is all that
- the simplifier ensures.
+Interaction of let-no-escape with SRTs [Sept 01]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
-NOTE THAT:
+ let-no-escape x = ...caf1...caf2...
+ in
+ ...x...x...x...
-* 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.
+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.
-* 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.
+This is unlike ordinary lets, in which the CAF refs are not duplicated.
-[Quite a bit of stuff that used to be here has moved
- to tidyCorePgm (SimplCore.lhs) SLPJ Nov 96]
+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}
%* *
%************************************************************************
-March 98: We keep a small 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.)
-
-A binder to be floated out becomes an @StgFloatBind@.
-
\begin{code}
-type StgEnv = IdEnv Id
-
-data StgFloatBind = NoBindF
- | RecF [(Id, StgRhs)]
- | NonRecF
- Id
- StgExpr -- *Can* be a StgLam
- RhsDemand
- [StgFloatBind]
-
--- The interesting one is the NonRecF
--- NonRecF x rhs demand binds
--- means
--- x = let binds in rhs
--- (or possibly case etc if x demand is strict)
--- The binds are kept separate so they can be floated futher
--- if appropriate
-\end{code}
+coreToStg :: DynFlags -> [CoreBind] -> IO [StgBinding]
+coreToStg dflags pgm
+ = return pgm'
+ where (_, _, pgm') = coreTopBindsToStg emptyVarEnv pgm
-A @RhsDemand@ gives the demand on an RHS: strict (@isStrictDem@) and
-thus case-bound, or if let-bound, at most once (@isOnceDem@) or
-otherwise.
+coreExprToStg :: CoreExpr -> StgExpr
+coreExprToStg expr
+ = new_expr where (new_expr,_,_) = initLne emptyVarEnv (coreToStgExpr expr)
-\begin{code}
-data RhsDemand = RhsDemand { isStrictDem :: Bool, -- True => used at least once
- isOnceDem :: Bool -- True => used at most once
- }
-mkDem :: Demand -> Bool -> RhsDemand
-mkDem strict once = RhsDemand (isStrict strict) once
+coreTopBindsToStg
+ :: IdEnv HowBound -- environment for the bindings
+ -> [CoreBind]
+ -> (IdEnv HowBound, FreeVarsInfo, [StgBinding])
-mkDemTy :: Demand -> Type -> RhsDemand
-mkDemTy strict ty = RhsDemand (isStrict strict) (isOnceTy ty)
+coreTopBindsToStg env [] = (env, emptyFVInfo, [])
+coreTopBindsToStg env (b:bs)
+ = (env2, fvs2, b':bs')
+ where
+ -- env accumulates down the list of binds, fvs accumulates upwards
+ (env1, fvs2, b' ) = coreTopBindToStg env fvs1 b
+ (env2, fvs1, bs') = coreTopBindsToStg env1 bs
+
+
+coreTopBindToStg
+ :: IdEnv HowBound
+ -> FreeVarsInfo -- Info about the body
+ -> CoreBind
+ -> (IdEnv HowBound, FreeVarsInfo, StgBinding)
+
+coreTopBindToStg 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 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 env body_fvs (Rec pairs)
+ = let
+ (binders, rhss) = unzip pairs
+
+ extra_env' = [ (b, LetBound TopLet (manifestArity rhs))
+ | (b, rhs) <- pairs ]
+ env' = extendVarEnvList env extra_env'
+
+ (stg_rhss, fvs')
+ = initLne env' (
+ mapAndUnzipLne (coreToTopStgRhs 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)
-isOnceTy :: Type -> Bool
-isOnceTy ty
- =
-#ifdef USMANY
- opt_UsageSPOn && -- can't expect annotations if -fusagesp is off
+#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
- case tyUsg ty of
- UsOnce -> True
- UsMany -> False
- UsVar uv -> pprPanic "CoreToStg: unexpected uvar annot:" (ppr uv)
+\end{code}
-bdrDem :: Id -> RhsDemand
-bdrDem id = mkDem (idDemandInfo id) (isOnceTy (idType id))
+\begin{code}
+coreToTopStgRhs
+ :: FreeVarsInfo -- Free var info for the scope of the binding
+ -> (Id,CoreExpr)
+ -> LneM (StgRhs, FreeVarsInfo)
+
+coreToTopStgRhs 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
+ bndr_info = lookupFVInfo scope_fv_info bndr
+ is_static = rhsIsStatic 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
-safeDem, onceDem :: RhsDemand
-safeDem = RhsDemand False False -- always safe to use this
-onceDem = RhsDemand False True -- used at most once
+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}
-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.
-When printing out the Stg we need non-bottom values in these
-locations.
+-- ---------------------------------------------------------------------------
+-- Expressions
+-- ---------------------------------------------------------------------------
\begin{code}
-bOGUS_LVs :: StgLiveVars
-bOGUS_LVs | opt_D_verbose_stg2stg = emptyUniqSet
- | otherwise =panic "bOGUS_LVs"
-
-bOGUS_FVs :: [Id]
-bOGUS_FVs | opt_D_verbose_stg2stg = []
- | otherwise = panic "bOGUS_FVs"
+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}
+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}
-topCoreBindsToStg :: UniqSupply -- name supply
- -> [CoreBind] -- input
- -> [StgBinding] -- output
+coreToStgExpr (Lit l) = returnLne (StgLit l, emptyFVInfo, emptyVarSet)
+coreToStgExpr (Var v) = coreToStgApp Nothing v []
-topCoreBindsToStg us core_binds
- = initUs_ us (coreBindsToStg emptyVarEnv core_binds)
+coreToStgExpr expr@(App _ _)
+ = coreToStgApp Nothing f args
where
- coreBindsToStg :: StgEnv -> [CoreBind] -> UniqSM [StgBinding]
-
- coreBindsToStg env [] = returnUs []
- coreBindsToStg env (b:bs)
- = coreBindToStg TopLevel env b `thenUs` \ (bind_spec, new_env) ->
- coreBindsToStg new_env bs `thenUs` \ new_bs ->
- case bind_spec of
- NonRecF bndr rhs dem floats
- -> ASSERT2( not (isStrictDem dem) &&
- not (isUnLiftedType (idType bndr)),
- ppr b ) -- No top-level cases!
-
- mkStgBinds floats rhs `thenUs` \ new_rhs ->
- returnUs (StgNonRec bndr (exprToRhs dem TopLevel new_rhs)
- : new_bs)
- -- Keep all the floats inside...
- -- Some might be cases etc
- -- We might want to revisit this decision
-
- RecF prs -> returnUs (StgRec prs : new_bs)
- NoBindF -> pprTrace "topCoreBindsToStg" (ppr b) $
- returnUs new_bs
-\end{code}
+ (f, args) = myCollectArgs expr
+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
+ fvs = args' `minusFVBinders` body_fvs
+ escs = body_escs `delVarSetList` args'
+ result_expr | null args' = body
+ | otherwise = StgLam (exprType expr) args' body
+ in
+ 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
-%************************************************************************
-%* *
-\subsection[coreToStg-binds]{Converting bindings}
-%* *
-%************************************************************************
+coreToStgExpr (Note other_note expr)
+ = coreToStgExpr expr
-\begin{code}
-coreBindToStg :: TopLevelFlag -> StgEnv -> CoreBind -> UniqSM (StgFloatBind, StgEnv)
-
-coreBindToStg top_lev env (NonRec binder rhs)
- = coreExprToStgFloat env rhs `thenUs` \ (floats, stg_rhs) ->
- case (floats, stg_rhs) of
- ([], StgApp var []) | not (isExportedId binder)
- -> returnUs (NoBindF, extendVarEnv env binder var)
- -- A trivial binding let x = y in ...
- -- can arise if postSimplExpr floats a NoRep literal out
- -- so it seems sensible to deal with it well.
- -- But we don't want to discard exported things. They can
- -- occur; e.g. an exported user binding f = g
-
- other -> newLocalId top_lev env binder `thenUs` \ (new_env, new_binder) ->
- returnUs (NonRecF new_binder stg_rhs dem floats, new_env)
- where
- dem = bdrDem binder
+-- 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
+ -- 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
-coreBindToStg top_lev env (Rec pairs)
- = newLocalIds top_lev env binders `thenUs` \ (env', binders') ->
- mapUs (do_rhs env') pairs `thenUs` \ stg_rhss ->
- returnUs (RecF (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))
+ 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
- binders = map fst pairs
- do_rhs env (bndr,rhs) = coreExprToStgFloat env rhs `thenUs` \ (floats, stg_expr) ->
- mkStgBinds floats stg_expr `thenUs` \ stg_expr' ->
- -- NB: stg_expr' might still be a StgLam (and we want that)
- returnUs (exprToRhs (bdrDem bndr) top_lev stg_expr')
+ 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}
+coreToStgExpr (Let bind body)
+ = fixLne (\ ~(_, _, _, no_binder_escapes) ->
+ coreToStgLet no_binder_escapes bind body
+ ) `thenLne` \ (new_let, fvs, escs, _) ->
+
+ returnLne (new_let, fvs, escs)
+\end{code}
\begin{code}
-exprToRhs :: RhsDemand -> TopLevelFlag -> StgExpr -> StgRhs
-exprToRhs dem _ (StgLam _ bndrs body)
- = ASSERT( not (null bndrs) )
- StgRhsClosure noCCS
- stgArgOcc
- noSRT
- bOGUS_FVs
- ReEntrant -- binders is non-empty
- bndrs
- body
-
-{-
- We reject the following candidates for 'static constructor'dom:
-
- - any dcon that takes a lit-lit as an arg.
- - [Win32 DLLs only]: any dcon that resides in a DLL
- (or takes as arg something that is.)
-
- These constraints are necessary to ensure that the code
- generated in the end for the static constructors, which
- live in the data segment, remain valid - i.e., it has to
- be constant. For obvious reasons, that's hard to guarantee
- with lit-lits. The second case of a constructor referring
- to static closures hiding out in some DLL is an artifact
- of the way Win32 DLLs handle global DLL variables. A (data)
- symbol exported from a DLL has to be accessed through a
- level of indirection at the site of use, so whereas
-
- extern StgClosure y_closure;
- extern StgClosure z_closure;
- x = { ..., &y_closure, &z_closure };
-
- is legal when the symbols are in scope at link-time, it is
- not when y_closure is in a DLL. So, any potential static
- closures that refers to stuff that's residing in a DLL
- will be put in an (updateable) thunk instead.
-
- An alternative strategy is to support the generation of
- constructors (ala C++ static class constructors) which will
- then be run at load time to fix up static closures.
--}
-exprToRhs dem toplev (StgConApp con args)
- | isNotTopLevel toplev ||
- (not is_dynamic &&
- all (not . isLitLitArg) args)
- = StgRhsCon noCCS con args
- where
- is_dynamic = isDynDataCon con || any (isDynArg) args
-
-exprToRhs dem _ expr
- = upd `seq`
- StgRhsClosure noCCS -- No cost centre (ToDo?)
- stgArgOcc -- safe
- noSRT -- figure out later
- bOGUS_FVs
- upd
- []
- expr
- where
- upd = if isOnceDem dem then SingleEntry else Updatable
- -- HA! Paydirt for "dem"
+mkStgAltType scrut_ty
+ = case splitTyConApp_maybe (repType scrut_ty) of
+ Just (tc,_) | isUnboxedTupleTyCon tc -> UbxTupAlt tc
+ | isPrimTyCon tc -> PrimAlt tc
+ | isHiBootTyCon tc -> PolyAlt -- Algebraic, but no constructors visible
+ | isAlgTyCon tc -> AlgAlt tc
+ | isFunTyCon tc -> PolyAlt
+ | otherwise -> pprPanic "mkStgAlts" (ppr tc)
+ Nothing -> PolyAlt
\end{code}
-%************************************************************************
-%* *
-\subsection[coreToStg-atoms{Converting atoms}
-%* *
-%************************************************************************
+-- ---------------------------------------------------------------------------
+-- Applications
+-- ---------------------------------------------------------------------------
\begin{code}
-coreArgsToStg :: StgEnv -> [(CoreArg,RhsDemand)] -> UniqSM ([StgFloatBind], [StgArg])
--- Arguments are all value arguments (tyargs already removed), paired with their demand
+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 ->
-coreArgsToStg env []
- = returnUs ([], [])
+ 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'
-coreArgsToStg env (ad:ads)
- = coreArgToStg env ad `thenUs` \ (bs1, a') ->
- coreArgsToStg env ads `thenUs` \ (bs2, as') ->
- returnUs (bs1 ++ bs2, a' : as')
+ in
+ 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.
+ )
-coreArgToStg :: StgEnv -> (CoreArg,RhsDemand) -> UniqSM ([StgFloatBind], StgArg)
--- This is where we arrange that a non-trivial argument is let-bound
-coreArgToStg env (arg,dem)
- = coreExprToStgFloat env arg `thenUs` \ (floats, arg') ->
- case arg' of
- StgApp v [] -> returnUs (floats, StgVarArg v)
- StgLit lit -> returnUs (floats, StgLitArg lit)
+-- ---------------------------------------------------------------------------
+-- Argument lists
+-- This is the guy that turns applications into A-normal form
+-- ---------------------------------------------------------------------------
- StgConApp con [] -> returnUs (floats, StgVarArg (dataConWrapId con))
- -- A nullary constructor can be replaced with
- -- a ``call'' to its wrapper
+coreToStgArgs :: [CoreArg] -> LneM ([StgArg], FreeVarsInfo)
+coreToStgArgs []
+ = returnLne ([], emptyFVInfo)
- other -> newStgVar arg_ty `thenUs` \ v ->
- returnUs ([NonRecF v arg' dem floats], StgVarArg v)
- where
- arg_ty = exprType arg
-\end{code}
+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
+ returnLne (args', fvs)
+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)
-%************************************************************************
-%* *
-\subsection[coreToStg-exprs]{Converting core expressions}
-%* *
-%************************************************************************
-\begin{code}
-coreExprToStg :: StgEnv -> CoreExpr -> UniqSM StgExpr
-coreExprToStg env expr
- = coreExprToStgFloat env expr `thenUs` \ (binds,stg_expr) ->
- mkStgBinds binds stg_expr `thenUs` \ stg_expr' ->
- deStgLam stg_expr'
-\end{code}
+-- ---------------------------------------------------------------------------
+-- The magic for lets:
+-- ---------------------------------------------------------------------------
-%************************************************************************
-%* *
-\subsubsection[coreToStg-let(rec)]{Let and letrec expressions}
-%* *
-%************************************************************************
+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
-\begin{code}
-coreExprToStgFloat :: StgEnv -> CoreExpr
- -> UniqSM ([StgFloatBind], StgExpr)
--- Transform an expression to STG. The 'floats' are
--- any bindings we had to create for function arguments.
-\end{code}
+coreToStgLet let_no_escape bind body
+ = fixLne (\ ~(_, _, _, _, _, rec_body_fvs, _, _) ->
-Simple cases first
+ -- 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) ->
-\begin{code}
-coreExprToStgFloat env (Var var)
- = mkStgApp env var [] (idType var) `thenUs` \ app ->
- returnUs ([], app)
+ -- Do the body
+ extendVarEnvLne env_ext (
+ coreToStgExpr body `thenLne` \(body2, body_fvs, body_escs) ->
+ freeVarsToLiveVars body_fvs `thenLne` \ body_lv_info ->
-coreExprToStgFloat env (Lit lit)
- = returnUs ([], StgLit lit)
+ returnLne (bind2, bind_fvs, bind_escs, getLiveVars bind_lv_info,
+ body2, body_fvs, body_escs, getLiveVars body_lv_info)
+ )
-coreExprToStgFloat env (Let bind body)
- = coreBindToStg NotTopLevel env bind `thenUs` \ (new_bind, new_env) ->
- coreExprToStgFloat new_env body `thenUs` \ (floats, stg_body) ->
- returnUs (new_bind:floats, stg_body)
-\end{code}
+ ) `thenLne` (\ (bind2, bind_fvs, bind_escs, bind_lvs,
+ body2, body_fvs, body_escs, body_lvs) ->
-Convert core @scc@ expression directly to STG @scc@ expression.
-\begin{code}
-coreExprToStgFloat env (Note (SCC cc) expr)
- = coreExprToStg env expr `thenUs` \ stg_expr ->
- returnUs ([], StgSCC cc stg_expr)
+ -- Compute the new let-expression
+ let
+ new_let | let_no_escape = StgLetNoEscape live_in_whole_let bind_lvs bind2 body2
+ | otherwise = StgLet bind2 body2
-coreExprToStgFloat env (Note other_note expr)
- = coreExprToStgFloat env expr
-\end{code}
+ free_in_whole_let
+ = binders `minusFVBinders` (bind_fvs `unionFVInfo` body_fvs)
-\begin{code}
-coreExprToStgFloat env expr@(Type _)
- = pprPanic "coreExprToStgFloat: tyarg unexpected:" $ ppr expr
-\end{code}
+ 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
-%************************************************************************
-%* *
-\subsubsection[coreToStg-lambdas]{Lambda abstractions}
-%* *
-%************************************************************************
+ let_escs = (real_bind_escs `unionVarSet` body_escs) `delVarSetList` binders
-\begin{code}
-coreExprToStgFloat env expr@(Lam _ _)
- = let
- expr_ty = exprType expr
- (binders, body) = collectBinders expr
- id_binders = filter isId 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
- if null id_binders then -- It was all type/usage binders; tossed
- coreExprToStgFloat env body
- else
- -- At least some value binders
- newLocalIds NotTopLevel env id_binders `thenUs` \ (env', binders') ->
- coreExprToStgFloat env' body `thenUs` \ (floats, stg_body) ->
- mkStgBinds floats stg_body `thenUs` \ stg_body' ->
-
- case stg_body' of
- StgLam ty lam_bndrs lam_body ->
- -- If the body reduced to a lambda too, join them up
- returnUs ([], mkStgLam expr_ty (binders' ++ lam_bndrs) lam_body)
-
- other ->
- -- Body didn't reduce to a lambda, so return one
- returnUs ([], mkStgLam expr_ty binders' stg_body')
+ returnLne (
+ new_let,
+ free_in_whole_let,
+ let_escs,
+ checked_no_binder_escapes
+ ))
+ where
+ 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 ($j)
+is_join_var j = occNameUserString (getOccName j) == "$j"
\end{code}
+\begin{code}
+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
-%************************************************************************
-%* *
-\subsubsection[coreToStg-applications]{Applications}
-%* *
-%************************************************************************
+mkStgRhs :: FreeVarsInfo -> SRT -> StgBinderInfo -> StgExpr -> StgRhs
-\begin{code}
-coreExprToStgFloat env expr@(App _ _)
- = let
- (fun,rads,ty,ss) = collect_args expr
- ads = reverse rads
- final_ads | null ss = ads
- | otherwise = zap ads -- Too few args to satisfy strictness info
- -- so we have to ignore all the strictness info
- -- e.g. + (error "urk")
- -- Here, we can't evaluate the arg strictly,
- -- because this partial application might be seq'd
- in
- coreArgsToStg env final_ads `thenUs` \ (arg_floats, stg_args) ->
-
- -- Now deal with the function
- case (fun, stg_args) of
- (Var fn_id, _) -> -- A function Id, so do an StgApp; it's ok if
- -- there are no arguments.
- mkStgApp env fn_id stg_args ty `thenUs` \ app ->
- returnUs (arg_floats, app)
-
- (non_var_fun, []) -> -- No value args, so recurse into the function
- ASSERT( null arg_floats )
- coreExprToStgFloat env non_var_fun
-
- other -> -- A non-variable applied to things; better let-bind it.
- newStgVar (exprType fun) `thenUs` \ fn_id ->
- coreExprToStgFloat env fun `thenUs` \ (fun_floats, stg_fun) ->
- mkStgApp env fn_id stg_args ty `thenUs` \ app ->
- returnUs (NonRecF fn_id stg_fun onceDem fun_floats : arg_floats,
- app)
+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
- -- Collect arguments and demands (*in reverse order*)
- -- collect_args e = (f, args_w_demands, ty, stricts)
- -- => e = f tys args, (i.e. args are just the value args)
- -- e :: ty
- -- stricts is the leftover demands of e on its further args
- -- If stricts runs out, we zap all the demands in args_w_demands
- -- because partial applications are lazy
-
- collect_args :: CoreExpr -> (CoreExpr, [(CoreExpr,RhsDemand)], Type, [Demand])
-
- collect_args (Note (Coerce ty _) e) = let (the_fun,ads,_,ss) = collect_args e
- in (the_fun,ads,ty,ss)
- collect_args (Note InlineCall e) = collect_args e
- collect_args (Note (TermUsg _) e) = collect_args e
-
- collect_args (App fun (Type tyarg)) = let (the_fun,ads,fun_ty,ss) = collect_args fun
- in (the_fun,ads,applyTy fun_ty tyarg,ss)
- collect_args (App fun arg)
- = (the_fun, (arg, mkDemTy ss1 arg_ty) : ads, res_ty, ss_rest)
- where
- (ss1, ss_rest) = case ss of
- (ss1:ss_rest) -> (ss1, ss_rest)
- [] -> (wwLazy, [])
- (the_fun, ads, fun_ty, ss) = collect_args fun
- (arg_ty, res_ty) = expectJust "coreExprToStgFloat:collect_args" $
- splitFunTy_maybe fun_ty
-
- collect_args (Var v)
- = (Var v, [], idType v, stricts)
- where
- stricts = case idStrictness v of
- StrictnessInfo demands _ -> demands
- other -> repeat wwLazy
+ 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}
- collect_args fun = (fun, [], exprType fun, repeat wwLazy)
+Detect thunks which will reduce immediately to PAPs, and make them
+non-updatable. This has several advantages:
- -- "zap" nukes the strictness info for a partial application
- zap ads = [(arg, RhsDemand False once) | (arg, RhsDemand _ once) <- ads]
-\end{code}
+ - the non-updatable thunk behaves exactly like the PAP,
+ - the thunk is more efficient to enter, because it is
+ specialised to the task.
-%************************************************************************
-%* *
-\subsubsection[coreToStg-cases]{Case expressions}
-%* *
-%************************************************************************
+ - we save one update frame, one stg_update_PAP, one update
+ and lots of PAP_enters.
-\begin{code}
-coreExprToStgFloat env (Case scrut bndr alts)
- = coreExprToStgFloat env scrut `thenUs` \ (binds, scrut') ->
- newLocalId NotTopLevel env bndr `thenUs` \ (env', bndr') ->
- alts_to_stg env' (findDefault alts) `thenUs` \ alts' ->
- returnUs (binds, mkStgCase scrut' bndr' alts')
- where
- scrut_ty = idType bndr
- prim_case = isUnLiftedType scrut_ty && not (isUnboxedTupleType scrut_ty)
-
- alts_to_stg env (alts, deflt)
- | prim_case
- = default_to_stg env deflt `thenUs` \ deflt' ->
- mapUs (prim_alt_to_stg env) alts `thenUs` \ alts' ->
- returnUs (mkStgPrimAlts scrut_ty alts' deflt')
-
- | otherwise
- = default_to_stg env deflt `thenUs` \ deflt' ->
- mapUs (alg_alt_to_stg env) alts `thenUs` \ alts' ->
- returnUs (mkStgAlgAlts scrut_ty alts' deflt')
-
- alg_alt_to_stg env (DataAlt con, bs, rhs)
- = newLocalIds NotTopLevel env (filter isId bs) `thenUs` \ (env', stg_bs) ->
- coreExprToStg env' rhs `thenUs` \ stg_rhs ->
- returnUs (con, stg_bs, [ True | b <- stg_bs ]{-bogus use mask-}, stg_rhs)
- -- NB the filter isId. Some of the binders may be
- -- existential type variables, which STG doesn't care about
-
- prim_alt_to_stg env (LitAlt lit, args, rhs)
- = ASSERT( null args )
- coreExprToStg env rhs `thenUs` \ stg_rhs ->
- returnUs (lit, stg_rhs)
-
- default_to_stg env Nothing
- = returnUs StgNoDefault
-
- default_to_stg env (Just rhs)
- = coreExprToStg env rhs `thenUs` \ stg_rhs ->
- returnUs (StgBindDefault stg_rhs)
- -- The binder is used for prim cases and not otherwise
- -- (hack for old code gen)
-\end{code}
+ - 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
%************************************************************************
%* *
-\subsection[coreToStg-misc]{Miscellaneous helping functions}
+\subsection[LNE-monad]{A little monad for this let-no-escaping pass}
%* *
%************************************************************************
-There's not anything interesting we can ASSERT about \tr{var} if it
-isn't in the StgEnv. (WDP 94/06)
+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*.
-Invent a fresh @Id@:
\begin{code}
-newStgVar :: Type -> UniqSM Id
-newStgVar ty
- = getUniqueUs `thenUs` \ uniq ->
- seqType ty `seq`
- returnUs (mkSysLocal SLIT("stg") uniq ty)
-\end{code}
+type LneM a = IdEnv HowBound
+ -> LiveInfo -- Vars and CAFs live in continuation
+ -> a
-\begin{code}
-newLocalId TopLevel env id
- -- Don't clone top-level binders. MkIface relies on their
- -- uniques staying the same, so it can snaffle IdInfo off the
- -- STG ids to put in interface files.
- = let
- name = idName id
- ty = idType id
- in
- name `seq`
- seqType ty `seq`
- returnUs (env, mkVanillaId name ty)
+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
-newLocalId NotTopLevel env id
- = -- Local binder, give it a new unique Id.
- getUniqueUs `thenUs` \ uniq ->
- let
- name = idName id
- ty = idType id
- new_id = mkVanillaId (setNameUnique name uniq) ty
- new_env = extendVarEnv env id new_id
- in
- name `seq`
- seqType ty `seq`
- returnUs (new_env, new_id)
-
-newLocalIds :: TopLevelFlag -> StgEnv -> [Id] -> UniqSM (StgEnv, [Id])
-newLocalIds top_lev env []
- = returnUs (env, [])
-newLocalIds top_lev env (b:bs)
- = newLocalId top_lev env b `thenUs` \ (env', b') ->
- newLocalIds top_lev env' bs `thenUs` \ (env'', bs') ->
- returnUs (env'', b':bs')
-\end{code}
+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)
-%************************************************************************
-%* *
-\subsection{Building STG syn}
-%* *
-%************************************************************************
+ | LambdaBound -- Used for both lambda and case
-\begin{code}
-mkStgAlgAlts ty alts deflt = seqType ty `seq` StgAlgAlts ty alts deflt
-mkStgPrimAlts ty alts deflt = seqType ty `seq` StgPrimAlts ty alts deflt
-mkStgLam ty bndrs body = seqType ty `seq` StgLam ty bndrs body
-
-mkStgApp :: StgEnv -> Id -> [StgArg] -> Type -> UniqSM StgExpr
- -- The type is the type of the entire application
-mkStgApp env fn args ty
- = case idFlavour fn_alias of
- DataConId dc
- -> saturate fn_alias args ty $ \ args' ty' ->
- returnUs (StgConApp dc args')
-
- PrimOpId (CCallOp (CCall (DynamicTarget _) a b c))
- -- Sigh...make a guaranteed unique name for a dynamic ccall
- -> saturate fn_alias args ty $ \ args' ty' ->
- getUniqueUs `thenUs` \ u ->
- returnUs (StgPrimApp (CCallOp (CCall (DynamicTarget u) a b c)) args' ty')
-
- PrimOpId op
- -> saturate fn_alias args ty $ \ args' ty' ->
- returnUs (StgPrimApp op args' ty')
-
- other -> returnUs (StgApp fn_alias args)
- -- Force the lookup
- where
- fn_alias = case (lookupVarEnv env fn) of -- In case it's been cloned
- Nothing -> fn
- Just fn' -> fn'
-
-saturate :: Id -> [StgArg] -> Type -> ([StgArg] -> Type -> UniqSM StgExpr) -> UniqSM StgExpr
-saturate fn args ty thing_inside
- | excess_arity == 0 -- Saturated, so nothing to do
- = thing_inside args ty
-
- | otherwise -- An unsaturated constructor or primop; eta expand it
- = ASSERT2( excess_arity > 0 && excess_arity <= length extra_arg_tys,
- ppr fn <+> ppr args <+> ppr excess_arity )
- mapUs newStgVar extra_arg_tys `thenUs` \ arg_vars ->
- thing_inside (args ++ map StgVarArg arg_vars) final_res_ty `thenUs` \ body ->
- returnUs (StgLam ty arg_vars body)
- where
- fn_arity = idArity fn
- excess_arity = fn_arity - length args
- (arg_tys, res_ty) = splitRepFunTys ty
- extra_arg_tys = take excess_arity arg_tys
- final_res_ty = mkFunTys (drop excess_arity arg_tys) res_ty
+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)
+
+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.
+
\begin{code}
--- Stg doesn't have a lambda *expression*
-deStgLam (StgLam ty bndrs body)
- -- Try for eta reduction
- = ASSERT( not (null bndrs) )
- case eta body of
- Just e -> -- Eta succeeded
- returnUs e
-
- Nothing -> -- Eta failed, so let-bind the lambda
- newStgVar ty `thenUs` \ fn ->
- returnUs (StgLet (StgNonRec fn lam_closure) (StgApp fn []))
- where
- lam_closure = StgRhsClosure noCCS
- stgArgOcc
- noSRT
- bOGUS_FVs
- ReEntrant -- binders is non-empty
- bndrs
- body
-
- eta (StgApp f args)
- | n_remaining >= 0 &&
- and (zipWith ok bndrs last_args) &&
- notInExpr bndrs remaining_expr
- = Just remaining_expr
- where
- remaining_expr = StgApp f remaining_args
- (remaining_args, last_args) = splitAt n_remaining args
- n_remaining = length args - length bndrs
+emptyLiveInfo :: LiveInfo
+emptyLiveInfo = (emptyVarSet,emptyVarSet)
- eta (StgLet bind@(StgNonRec b r) body)
- | notInRhs bndrs r = case eta body of
- Just e -> Just (StgLet bind e)
- Nothing -> Nothing
+unitLiveVar :: Id -> LiveInfo
+unitLiveVar lv = (unitVarSet lv, emptyVarSet)
- eta _ = Nothing
+unitLiveCaf :: Id -> LiveInfo
+unitLiveCaf caf = (emptyVarSet, unitVarSet caf)
- ok bndr (StgVarArg arg) = bndr == arg
- ok bndr other = False
+addLiveVar :: LiveInfo -> Id -> LiveInfo
+addLiveVar (lvs, cafs) id = (lvs `extendVarSet` id, cafs)
-deStgLam expr = returnUs expr
+unionLiveInfo :: LiveInfo -> LiveInfo -> LiveInfo
+unionLiveInfo (lv1,caf1) (lv2,caf2) = (lv1 `unionVarSet` lv2, caf1 `unionVarSet` caf2)
+mkSRT :: LiveInfo -> SRT
+mkSRT (_, cafs) = SRTEntries cafs
---------------------------------------------------
-notInExpr :: [Id] -> StgExpr -> Bool
-notInExpr vs (StgApp f args) = notInId vs f && notInArgs vs args
-notInExpr vs (StgLet (StgNonRec b r) body) = notInRhs vs r && notInExpr vs body
-notInExpr vs other = False -- Safe
+getLiveVars :: LiveInfo -> StgLiveVars
+getLiveVars (lvs, _) = lvs
+\end{code}
-notInRhs :: [Id] -> StgRhs -> Bool
-notInRhs vs (StgRhsCon _ _ args) = notInArgs vs args
-notInRhs vs (StgRhsClosure _ _ _ _ _ _ body) = notInExpr vs body
- -- Conservative: we could delete the binders from vs, but
- -- cloning means this will never help
-notInArgs :: [Id] -> [StgArg] -> Bool
-notInArgs vs args = all ok args
- where
- ok (StgVarArg v) = notInId vs v
- ok (StgLitArg l) = True
+The std monad functions:
+\begin{code}
+initLne :: IdEnv HowBound -> LneM a -> a
+initLne env m = m env emptyLiveInfo
-notInId :: [Id] -> Id -> Bool
-notInId vs v = not (v `elem` vs)
+{-# INLINE thenLne #-}
+{-# INLINE returnLne #-}
-mkStgBinds :: [StgFloatBind]
- -> StgExpr -- *Can* be a StgLam
- -> UniqSM StgExpr -- *Can* be a StgLam
+returnLne :: a -> LneM a
+returnLne e env lvs_cont = e
-mkStgBinds [] body = returnUs body
-mkStgBinds (b:bs) body
- = deStgLam body `thenUs` \ body' ->
- go (b:bs) body'
- where
- go [] body = returnUs body
- go (b:bs) body = go bs body `thenUs` \ body' ->
- mkStgBind b body'
+thenLne :: LneM a -> (a -> LneM b) -> LneM b
+thenLne m k env lvs_cont
+ = k (m env lvs_cont) env lvs_cont
--- The 'body' arg of mkStgBind can't be a StgLam
-mkStgBind NoBindF body = returnUs body
-mkStgBind (RecF prs) body = returnUs (StgLet (StgRec prs) body)
+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)
-mkStgBind (NonRecF bndr rhs dem floats) body
-#ifdef DEBUG
- -- We shouldn't get let or case of the form v=w
- = case rhs of
- StgApp v [] -> pprTrace "mkStgLet" (ppr bndr <+> ppr v)
- (mk_stg_let bndr rhs dem floats body)
- other -> mk_stg_let bndr rhs dem floats body
+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)
-mk_stg_let bndr rhs dem floats body
-#endif
- | isUnLiftedType bndr_rep_ty -- Use a case/PrimAlts
- = ASSERT( not (isUnboxedTupleType bndr_rep_ty) )
- mkStgBinds floats $
- mkStgCase rhs bndr (StgPrimAlts bndr_rep_ty [] (StgBindDefault body))
-
- | is_whnf
- = if is_strict then
- -- Strict let with WHNF rhs
- mkStgBinds floats $
- StgLet (StgNonRec bndr (exprToRhs dem NotTopLevel rhs)) body
- else
- -- Lazy let with WHNF rhs; float until we find a strict binding
- let
- (floats_out, floats_in) = splitFloats floats
- in
- mkStgBinds floats_in rhs `thenUs` \ new_rhs ->
- mkStgBinds floats_out $
- StgLet (StgNonRec bndr (exprToRhs dem NotTopLevel new_rhs)) body
-
- | otherwise -- Not WHNF
- = if is_strict then
- -- Strict let with non-WHNF rhs
- mkStgBinds floats $
- mkStgCase rhs bndr (StgAlgAlts bndr_rep_ty [] (StgBindDefault body))
- else
- -- Lazy let with non-WHNF rhs, so keep the floats in the RHS
- mkStgBinds floats rhs `thenUs` \ new_rhs ->
- returnUs (StgLet (StgNonRec bndr (exprToRhs dem NotTopLevel new_rhs)) body)
-
+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
- bndr_rep_ty = repType (idType bndr)
- is_strict = isStrictDem dem
- is_whnf = case rhs of
- StgConApp _ _ -> True
- StgLam _ _ _ -> True
- other -> False
+ result = expr result env lvs_cont
+\end{code}
--- Split at the first strict binding
-splitFloats fs@(NonRecF _ _ dem _ : _)
- | isStrictDem dem = ([], fs)
+Functions specific to this monad:
-splitFloats (f : fs) = case splitFloats fs of
- (fs_out, fs_in) -> (f : fs_out, fs_in)
+\begin{code}
+getVarsLiveInCont :: LneM LiveInfo
+getVarsLiveInCont env lvs_cont = lvs_cont
-splitFloats [] = ([], [])
-\end{code}
+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
-Making an STG case
-~~~~~~~~~~~~~~~~~~
+lookupVarLne :: Id -> LneM HowBound
+lookupVarLne v env lvs_cont = returnLne (lookupBinding env v) env lvs_cont
-First, two special cases. We mangle cases involving
- par# and seq#
-inthe scrutinee.
+getEnvLne :: LneM (IdEnv HowBound)
+getEnvLne env lvs_cont = returnLne env env lvs_cont
-Up to this point, seq# will appear like this:
+lookupBinding :: IdEnv HowBound -> Id -> HowBound
+lookupBinding env v = case lookupVarEnv env v of
+ Just xx -> xx
+ Nothing -> ASSERT2( isGlobalId v, ppr v ) ImportBound
- case seq# e of
- 0# -> seqError#
- _ -> <stuff>
-This code comes from an unfolding for 'seq' in Prelude.hs.
-The 0# branch is purely to bamboozle the strictness analyser.
-For example, if <stuff> is strict in x, and there was no seqError#
-branch, the strictness analyser would conclude that the whole expression
-was strict in x, and perhaps evaluate x first -- but that would be a DISASTER.
+-- 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.
-Now that the evaluation order is safe, we translate this into
+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)
- case e of
- _ -> ...
+ 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
-This used to be done in the post-simplification phase, but we need
-unfoldings involving seq# to appear unmangled in the interface file,
-hence we do this mangling here.
+ LetBound (NestedLet lvs) _ -> lvs -- lvs already contains v
+ -- (see the invariant on NestedLet)
-Similarly, par# has an unfolding in PrelConc.lhs that makes it show
-up like this:
+ _lambda_or_case_binding -> unitLiveVar v -- Bound by lambda or case
+\end{code}
- case par# e of
- 0# -> rhs
- _ -> parError#
+%************************************************************************
+%* *
+\subsection[Free-var info]{Free variable information}
+%* *
+%************************************************************************
+\begin{code}
+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}
- ==>
- case par# e of
- _ -> rhs
+\begin{code}
+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,_) <- rngVarEnv 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, _) <- rngVarEnv 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)
-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.
+#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}
+filterStgBinders :: [Var] -> [Var]
+filterStgBinders bndrs
+ | opt_RuntimeTypes = bndrs
+ | otherwise = filter isId bndrs
+\end{code}
\begin{code}
--- Discard alernatives in case (par# ..) of
-mkStgCase scrut@(StgPrimApp ParOp _ _) bndr
- (StgPrimAlts ty _ deflt@(StgBindDefault _))
- = StgCase scrut bOGUS_LVs bOGUS_LVs bndr noSRT (StgPrimAlts ty [] deflt)
-
-mkStgCase (StgPrimApp SeqOp [scrut] _) bndr
- (StgPrimAlts _ _ deflt@(StgBindDefault rhs))
- = mkStgCase scrut_expr new_bndr (StgAlgAlts scrut_ty [] (StgBindDefault rhs))
+ -- 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
- new_alts | isUnLiftedType scrut_ty = WARN( True, text "mkStgCase" ) StgPrimAlts scrut_ty [] deflt
- | otherwise = StgAlgAlts scrut_ty [] deflt
- scrut_ty = stgArgType scrut
- new_bndr = setIdType bndr scrut_ty
- -- NB: SeqOp :: forall a. a -> Int#
- -- So bndr has type Int#
- -- But now we are going to scrutinise the SeqOp's argument directly,
- -- so we must change the type of the case binder to match that
- -- of the argument expression e.
-
- scrut_expr = case scrut of
- StgVarArg v -> StgApp v []
- -- Others should not happen because
- -- seq of a value should have disappeared
- StgLitArg l -> WARN( True, text "seq on" <+> ppr l ) StgLit l
-
-mkStgCase scrut bndr alts
- = ASSERT( case scrut of { StgLam _ _ _ -> False; other -> True } )
- -- We should never find
- -- case (\x->e) of { ... }
- -- The simplifier eliminates such things
- StgCase scrut bOGUS_LVs bOGUS_LVs bndr noSRT alts
+ 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}
+
+\begin{code}
+stgArity :: Id -> HowBound -> Arity
+stgArity f (LetBound _ arity) = arity
+stgArity f ImportBound = idArity f
+stgArity f LambdaBound = 0
\end{code}
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