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Diffstat (limited to 'compiler/codeGen/ClosureInfo.lhs')
| -rw-r--r-- | compiler/codeGen/ClosureInfo.lhs | 951 |
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diff --git a/compiler/codeGen/ClosureInfo.lhs b/compiler/codeGen/ClosureInfo.lhs new file mode 100644 index 0000000000..84d9dd95ef --- /dev/null +++ b/compiler/codeGen/ClosureInfo.lhs @@ -0,0 +1,951 @@ +% +% (c) The Univserity of Glasgow 1992-2004 +% + + Data structures which describe closures, and + operations over those data structures + + Nothing monadic in here + +Much of the rationale for these things is in the ``details'' part of +the STG paper. + +\begin{code} +module ClosureInfo ( + ClosureInfo, LambdaFormInfo, SMRep, -- all abstract + StandardFormInfo, + + ArgDescr(..), Liveness(..), + C_SRT(..), needsSRT, + + mkLFThunk, mkLFReEntrant, mkConLFInfo, mkSelectorLFInfo, + mkApLFInfo, mkLFImported, mkLFArgument, mkLFLetNoEscape, + + mkClosureInfo, mkConInfo, + + closureSize, closureNonHdrSize, + closureGoodStuffSize, closurePtrsSize, + slopSize, + + closureName, infoTableLabelFromCI, + closureLabelFromCI, closureSRT, + closureLFInfo, isLFThunk,closureSMRep, closureUpdReqd, + closureNeedsUpdSpace, closureIsThunk, + closureSingleEntry, closureReEntrant, isConstrClosure_maybe, + closureFunInfo, isStandardFormThunk, isKnownFun, + + enterIdLabel, enterLocalIdLabel, enterReturnPtLabel, + + nodeMustPointToIt, + CallMethod(..), getCallMethod, + + blackHoleOnEntry, + + staticClosureRequired, + getClosureType, + + isToplevClosure, + closureValDescr, closureTypeDescr, -- profiling + + isStaticClosure, + cafBlackHoleClosureInfo, seCafBlackHoleClosureInfo, + + staticClosureNeedsLink, + ) where + +#include "../includes/MachDeps.h" +#include "HsVersions.h" + +import StgSyn +import SMRep -- all of it + +import CLabel + +import Constants ( mIN_PAYLOAD_SIZE ) +import Packages ( isDllName, HomeModules ) +import StaticFlags ( opt_SccProfilingOn, opt_OmitBlackHoling, + opt_Parallel, opt_DoTickyProfiling ) +import Id ( Id, idType, idArity, idName ) +import DataCon ( DataCon, dataConTyCon, isNullaryRepDataCon, dataConName ) +import Name ( Name, nameUnique, getOccName, getOccString ) +import OccName ( occNameString ) +import Type ( isUnLiftedType, Type, repType, splitTyConApp_maybe ) +import TcType ( tcSplitSigmaTy ) +import TyCon ( isFunTyCon, isAbstractTyCon ) +import BasicTypes ( TopLevelFlag(..), isNotTopLevel, isTopLevel, ipNameName ) +import FastString +import Outputable +import Constants + +import TypeRep -- TEMP +\end{code} + + +%************************************************************************ +%* * +\subsection[ClosureInfo-datatypes]{Data types for closure information} +%* * +%************************************************************************ + +Information about a closure, from the code generator's point of view. + +A ClosureInfo decribes the info pointer of a closure. It has +enough information + a) to construct the info table itself + b) to allocate a closure containing that info pointer (i.e. + it knows the info table label) + +We make a ClosureInfo for + - each let binding (both top level and not) + - each data constructor (for its shared static and + dynamic info tables) + +\begin{code} +data ClosureInfo + = ClosureInfo { + closureName :: !Name, -- The thing bound to this closure + closureLFInfo :: !LambdaFormInfo, -- NOTE: not an LFCon (see below) + closureSMRep :: !SMRep, -- representation used by storage mgr + closureSRT :: !C_SRT, -- What SRT applies to this closure + closureType :: !Type, -- Type of closure (ToDo: remove) + closureDescr :: !String -- closure description (for profiling) + } + + -- Constructor closures don't have a unique info table label (they use + -- the constructor's info table), and they don't have an SRT. + | ConInfo { + closureCon :: !DataCon, + closureSMRep :: !SMRep, + closureDllCon :: !Bool -- is in a separate DLL + } + +-- C_SRT is what StgSyn.SRT gets translated to... +-- we add a label for the table, and expect only the 'offset/length' form + +data C_SRT = NoC_SRT + | C_SRT !CLabel !WordOff !StgHalfWord {-bitmap or escape-} + +needsSRT :: C_SRT -> Bool +needsSRT NoC_SRT = False +needsSRT (C_SRT _ _ _) = True +\end{code} + +%************************************************************************ +%* * +\subsubsection[LambdaFormInfo-datatype]{@LambdaFormInfo@: source-derivable info} +%* * +%************************************************************************ + +Information about an identifier, from the code generator's point of +view. Every identifier is bound to a LambdaFormInfo in the +environment, which gives the code generator enough info to be able to +tail call or return that identifier. + +Note that a closure is usually bound to an identifier, so a +ClosureInfo contains a LambdaFormInfo. + +\begin{code} +data LambdaFormInfo + = LFReEntrant -- Reentrant closure (a function) + TopLevelFlag -- True if top level + !Int -- Arity. Invariant: always > 0 + !Bool -- True <=> no fvs + ArgDescr -- Argument descriptor (should reall be in ClosureInfo) + + | LFCon -- A saturated constructor application + DataCon -- The constructor + + | LFThunk -- Thunk (zero arity) + TopLevelFlag + !Bool -- True <=> no free vars + !Bool -- True <=> updatable (i.e., *not* single-entry) + StandardFormInfo + !Bool -- True <=> *might* be a function type + + | LFUnknown -- Used for function arguments and imported things. + -- We know nothing about this closure. Treat like + -- updatable "LFThunk"... + -- Imported things which we do know something about use + -- one of the other LF constructors (eg LFReEntrant for + -- known functions) + !Bool -- True <=> *might* be a function type + + | LFLetNoEscape -- See LetNoEscape module for precise description of + -- these "lets". + !Int -- arity; + + | LFBlackHole -- Used for the closures allocated to hold the result + -- of a CAF. We want the target of the update frame to + -- be in the heap, so we make a black hole to hold it. + CLabel -- Flavour (info label, eg CAF_BLACKHOLE_info). + + +------------------------- +-- An ArgDsecr describes the argument pattern of a function + +data ArgDescr + = ArgSpec -- Fits one of the standard patterns + !Int -- RTS type identifier ARG_P, ARG_N, ... + + | ArgGen -- General case + Liveness -- Details about the arguments + + +------------------------- +-- We represent liveness bitmaps as a Bitmap (whose internal +-- representation really is a bitmap). These are pinned onto case return +-- vectors to indicate the state of the stack for the garbage collector. +-- +-- In the compiled program, liveness bitmaps that fit inside a single +-- word (StgWord) are stored as a single word, while larger bitmaps are +-- stored as a pointer to an array of words. + +data Liveness + = SmallLiveness -- Liveness info that fits in one word + StgWord -- Here's the bitmap + + | BigLiveness -- Liveness info witha a multi-word bitmap + CLabel -- Label for the bitmap + + +------------------------- +-- StandardFormInfo tells whether this thunk has one of +-- a small number of standard forms + +data StandardFormInfo + = NonStandardThunk + -- Not of of the standard forms + + | SelectorThunk + -- A SelectorThunk is of form + -- case x of + -- con a1,..,an -> ak + -- and the constructor is from a single-constr type. + WordOff -- 0-origin offset of ak within the "goods" of + -- constructor (Recall that the a1,...,an may be laid + -- out in the heap in a non-obvious order.) + + | ApThunk + -- An ApThunk is of form + -- x1 ... xn + -- The code for the thunk just pushes x2..xn on the stack and enters x1. + -- There are a few of these (for 1 <= n <= MAX_SPEC_AP_SIZE) pre-compiled + -- in the RTS to save space. + Int -- Arity, n +\end{code} + +%************************************************************************ +%* * +\subsection[ClosureInfo-construction]{Functions which build LFInfos} +%* * +%************************************************************************ + +\begin{code} +mkLFReEntrant :: TopLevelFlag -- True of top level + -> [Id] -- Free vars + -> [Id] -- Args + -> ArgDescr -- Argument descriptor + -> LambdaFormInfo + +mkLFReEntrant top fvs args arg_descr + = LFReEntrant top (length args) (null fvs) arg_descr + +mkLFThunk thunk_ty top fvs upd_flag + = ASSERT( not (isUpdatable upd_flag) || not (isUnLiftedType thunk_ty) ) + LFThunk top (null fvs) + (isUpdatable upd_flag) + NonStandardThunk + (might_be_a_function thunk_ty) + +might_be_a_function :: Type -> Bool +might_be_a_function ty + | Just (tc,_) <- splitTyConApp_maybe (repType ty), + not (isFunTyCon tc) && not (isAbstractTyCon tc) = False + -- don't forget to check for abstract types, which might + -- be functions too. + | otherwise = True +\end{code} + +@mkConLFInfo@ is similar, for constructors. + +\begin{code} +mkConLFInfo :: DataCon -> LambdaFormInfo +mkConLFInfo con = LFCon con + +mkSelectorLFInfo id offset updatable + = LFThunk NotTopLevel False updatable (SelectorThunk offset) + (might_be_a_function (idType id)) + +mkApLFInfo id upd_flag arity + = LFThunk NotTopLevel (arity == 0) (isUpdatable upd_flag) (ApThunk arity) + (might_be_a_function (idType id)) +\end{code} + +Miscellaneous LF-infos. + +\begin{code} +mkLFArgument id = LFUnknown (might_be_a_function (idType id)) + +mkLFLetNoEscape = LFLetNoEscape + +mkLFImported :: Id -> LambdaFormInfo +mkLFImported id + = case idArity id of + n | n > 0 -> LFReEntrant TopLevel n True (panic "arg_descr") -- n > 0 + other -> mkLFArgument id -- Not sure of exact arity +\end{code} + +\begin{code} +isLFThunk :: LambdaFormInfo -> Bool +isLFThunk (LFThunk _ _ _ _ _) = True +isLFThunk (LFBlackHole _) = True + -- return True for a blackhole: this function is used to determine + -- whether to use the thunk header in SMP mode, and a blackhole + -- must have one. +isLFThunk _ = False +\end{code} + +%************************************************************************ +%* * + Building ClosureInfos +%* * +%************************************************************************ + +\begin{code} +mkClosureInfo :: Bool -- Is static + -> Id + -> LambdaFormInfo + -> Int -> Int -- Total and pointer words + -> C_SRT + -> String -- String descriptor + -> ClosureInfo +mkClosureInfo is_static id lf_info tot_wds ptr_wds srt_info descr + = ClosureInfo { closureName = name, + closureLFInfo = lf_info, + closureSMRep = sm_rep, + closureSRT = srt_info, + closureType = idType id, + closureDescr = descr } + where + name = idName id + sm_rep = chooseSMRep is_static lf_info tot_wds ptr_wds + +mkConInfo :: HomeModules + -> Bool -- Is static + -> DataCon + -> Int -> Int -- Total and pointer words + -> ClosureInfo +mkConInfo hmods is_static data_con tot_wds ptr_wds + = ConInfo { closureSMRep = sm_rep, + closureCon = data_con, + closureDllCon = isDllName hmods (dataConName data_con) } + where + sm_rep = chooseSMRep is_static (mkConLFInfo data_con) tot_wds ptr_wds +\end{code} + +%************************************************************************ +%* * +\subsection[ClosureInfo-sizes]{Functions about closure {\em sizes}} +%* * +%************************************************************************ + +\begin{code} +closureSize :: ClosureInfo -> WordOff +closureSize cl_info = hdr_size + closureNonHdrSize cl_info + where hdr_size | closureIsThunk cl_info = thunkHdrSize + | otherwise = fixedHdrSize + -- All thunks use thunkHdrSize, even if they are non-updatable. + -- this is because we don't have separate closure types for + -- updatable vs. non-updatable thunks, so the GC can't tell the + -- difference. If we ever have significant numbers of non- + -- updatable thunks, it might be worth fixing this. + +closureNonHdrSize :: ClosureInfo -> WordOff +closureNonHdrSize cl_info + = tot_wds + computeSlopSize tot_wds cl_info + where + tot_wds = closureGoodStuffSize cl_info + +closureGoodStuffSize :: ClosureInfo -> WordOff +closureGoodStuffSize cl_info + = let (ptrs, nonptrs) = sizes_from_SMRep (closureSMRep cl_info) + in ptrs + nonptrs + +closurePtrsSize :: ClosureInfo -> WordOff +closurePtrsSize cl_info + = let (ptrs, _) = sizes_from_SMRep (closureSMRep cl_info) + in ptrs + +-- not exported: +sizes_from_SMRep :: SMRep -> (WordOff,WordOff) +sizes_from_SMRep (GenericRep _ ptrs nonptrs _) = (ptrs, nonptrs) +sizes_from_SMRep BlackHoleRep = (0, 0) +\end{code} + +Computing slop size. WARNING: this looks dodgy --- it has deep +knowledge of what the storage manager does with the various +representations... + +Slop Requirements: every thunk gets an extra padding word in the +header, which takes the the updated value. + +\begin{code} +slopSize cl_info = computeSlopSize payload_size cl_info + where payload_size = closureGoodStuffSize cl_info + +computeSlopSize :: WordOff -> ClosureInfo -> WordOff +computeSlopSize payload_size cl_info + = max 0 (minPayloadSize smrep updatable - payload_size) + where + smrep = closureSMRep cl_info + updatable = closureNeedsUpdSpace cl_info + +-- we leave space for an update if either (a) the closure is updatable +-- or (b) it is a static thunk. This is because a static thunk needs +-- a static link field in a predictable place (after the slop), regardless +-- of whether it is updatable or not. +closureNeedsUpdSpace (ClosureInfo { closureLFInfo = + LFThunk TopLevel _ _ _ _ }) = True +closureNeedsUpdSpace cl_info = closureUpdReqd cl_info + +minPayloadSize :: SMRep -> Bool -> WordOff +minPayloadSize smrep updatable + = case smrep of + BlackHoleRep -> min_upd_size + GenericRep _ _ _ _ | updatable -> min_upd_size + GenericRep True _ _ _ -> 0 -- static + GenericRep False _ _ _ -> mIN_PAYLOAD_SIZE + -- ^^^^^___ dynamic + where + min_upd_size = + ASSERT(mIN_PAYLOAD_SIZE <= sIZEOF_StgSMPThunkHeader) + 0 -- check that we already have enough + -- room for mIN_SIZE_NonUpdHeapObject, + -- due to the extra header word in SMP +\end{code} + +%************************************************************************ +%* * +\subsection[SMreps]{Choosing SM reps} +%* * +%************************************************************************ + +\begin{code} +chooseSMRep + :: Bool -- True <=> static closure + -> LambdaFormInfo + -> WordOff -> WordOff -- Tot wds, ptr wds + -> SMRep + +chooseSMRep is_static lf_info tot_wds ptr_wds + = let + nonptr_wds = tot_wds - ptr_wds + closure_type = getClosureType is_static ptr_wds lf_info + in + GenericRep is_static ptr_wds nonptr_wds closure_type + +-- We *do* get non-updatable top-level thunks sometimes. eg. f = g +-- gets compiled to a jump to g (if g has non-zero arity), instead of +-- messing around with update frames and PAPs. We set the closure type +-- to FUN_STATIC in this case. + +getClosureType :: Bool -> WordOff -> LambdaFormInfo -> ClosureType +getClosureType is_static ptr_wds lf_info + = case lf_info of + LFCon con | is_static && ptr_wds == 0 -> ConstrNoCaf + | otherwise -> Constr + LFReEntrant _ _ _ _ -> Fun + LFThunk _ _ _ (SelectorThunk _) _ -> ThunkSelector + LFThunk _ _ _ _ _ -> Thunk + _ -> panic "getClosureType" +\end{code} + +%************************************************************************ +%* * +\subsection[ClosureInfo-4-questions]{Four major questions about @ClosureInfo@} +%* * +%************************************************************************ + +Be sure to see the stg-details notes about these... + +\begin{code} +nodeMustPointToIt :: LambdaFormInfo -> Bool +nodeMustPointToIt (LFReEntrant top _ no_fvs _) + = not no_fvs || -- Certainly if it has fvs we need to point to it + isNotTopLevel top + -- If it is not top level we will point to it + -- We can have a \r closure with no_fvs which + -- is not top level as special case cgRhsClosure + -- has been dissabled in favour of let floating + + -- For lex_profiling we also access the cost centre for a + -- non-inherited function i.e. not top level + -- the not top case above ensures this is ok. + +nodeMustPointToIt (LFCon _) = True + + -- Strictly speaking, the above two don't need Node to point + -- to it if the arity = 0. But this is a *really* unlikely + -- situation. If we know it's nil (say) and we are entering + -- it. Eg: let x = [] in x then we will certainly have inlined + -- x, since nil is a simple atom. So we gain little by not + -- having Node point to known zero-arity things. On the other + -- hand, we do lose something; Patrick's code for figuring out + -- when something has been updated but not entered relies on + -- having Node point to the result of an update. SLPJ + -- 27/11/92. + +nodeMustPointToIt (LFThunk _ no_fvs updatable NonStandardThunk _) + = updatable || not no_fvs || opt_SccProfilingOn + -- For the non-updatable (single-entry case): + -- + -- True if has fvs (in which case we need access to them, and we + -- should black-hole it) + -- or profiling (in which case we need to recover the cost centre + -- from inside it) + +nodeMustPointToIt (LFThunk _ no_fvs updatable some_standard_form_thunk _) + = True -- Node must point to any standard-form thunk + +nodeMustPointToIt (LFUnknown _) = True +nodeMustPointToIt (LFBlackHole _) = True -- BH entry may require Node to point +nodeMustPointToIt (LFLetNoEscape _) = False +\end{code} + +The entry conventions depend on the type of closure being entered, +whether or not it has free variables, and whether we're running +sequentially or in parallel. + +\begin{tabular}{lllll} +Closure Characteristics & Parallel & Node Req'd & Argument Passing & Enter Via \\ +Unknown & no & yes & stack & node \\ +Known fun ($\ge$ 1 arg), no fvs & no & no & registers & fast entry (enough args) \\ +\ & \ & \ & \ & slow entry (otherwise) \\ +Known fun ($\ge$ 1 arg), fvs & no & yes & registers & fast entry (enough args) \\ +0 arg, no fvs @\r,\s@ & no & no & n/a & direct entry \\ +0 arg, no fvs @\u@ & no & yes & n/a & node \\ +0 arg, fvs @\r,\s@ & no & yes & n/a & direct entry \\ +0 arg, fvs @\u@ & no & yes & n/a & node \\ + +Unknown & yes & yes & stack & node \\ +Known fun ($\ge$ 1 arg), no fvs & yes & no & registers & fast entry (enough args) \\ +\ & \ & \ & \ & slow entry (otherwise) \\ +Known fun ($\ge$ 1 arg), fvs & yes & yes & registers & node \\ +0 arg, no fvs @\r,\s@ & yes & no & n/a & direct entry \\ +0 arg, no fvs @\u@ & yes & yes & n/a & node \\ +0 arg, fvs @\r,\s@ & yes & yes & n/a & node \\ +0 arg, fvs @\u@ & yes & yes & n/a & node\\ +\end{tabular} + +When black-holing, single-entry closures could also be entered via node +(rather than directly) to catch double-entry. + +\begin{code} +data CallMethod + = EnterIt -- no args, not a function + + | JumpToIt CLabel -- no args, not a function, but we + -- know what its entry code is + + | ReturnIt -- it's a function, but we have + -- zero args to apply to it, so just + -- return it. + + | ReturnCon DataCon -- It's a data constructor, just return it + + | SlowCall -- Unknown fun, or known fun with + -- too few args. + + | DirectEntry -- Jump directly, with args in regs + CLabel -- The code label + Int -- Its arity + +getCallMethod :: HomeModules + -> Name -- Function being applied + -> LambdaFormInfo -- Its info + -> Int -- Number of available arguments + -> CallMethod + +getCallMethod hmods name lf_info n_args + | nodeMustPointToIt lf_info && opt_Parallel + = -- If we're parallel, then we must always enter via node. + -- The reason is that the closure may have been + -- fetched since we allocated it. + EnterIt + +getCallMethod hmods name (LFReEntrant _ arity _ _) n_args + | n_args == 0 = ASSERT( arity /= 0 ) + ReturnIt -- No args at all + | n_args < arity = SlowCall -- Not enough args + | otherwise = DirectEntry (enterIdLabel hmods name) arity + +getCallMethod hmods name (LFCon con) n_args + = ASSERT( n_args == 0 ) + ReturnCon con + +getCallMethod hmods name (LFThunk _ _ updatable std_form_info is_fun) n_args + | is_fun -- Must always "call" a function-typed + = SlowCall -- thing, cannot just enter it [in eval/apply, the entry code + -- is the fast-entry code] + + | updatable || opt_DoTickyProfiling -- to catch double entry + {- OLD: || opt_SMP + I decided to remove this, because in SMP mode it doesn't matter + if we enter the same thunk multiple times, so the optimisation + of jumping directly to the entry code is still valid. --SDM + -} + = ASSERT( n_args == 0 ) EnterIt + + | otherwise -- Jump direct to code for single-entry thunks + = ASSERT( n_args == 0 ) + JumpToIt (thunkEntryLabel hmods name std_form_info updatable) + +getCallMethod hmods name (LFUnknown True) n_args + = SlowCall -- might be a function + +getCallMethod hmods name (LFUnknown False) n_args + = ASSERT2 ( n_args == 0, ppr name <+> ppr n_args ) + EnterIt -- Not a function + +getCallMethod hmods name (LFBlackHole _) n_args + = SlowCall -- Presumably the black hole has by now + -- been updated, but we don't know with + -- what, so we slow call it + +getCallMethod hmods name (LFLetNoEscape 0) n_args + = JumpToIt (enterReturnPtLabel (nameUnique name)) + +getCallMethod hmods name (LFLetNoEscape arity) n_args + | n_args == arity = DirectEntry (enterReturnPtLabel (nameUnique name)) arity + | otherwise = pprPanic "let-no-escape: " (ppr name <+> ppr arity) + +blackHoleOnEntry :: ClosureInfo -> Bool +-- Static closures are never themselves black-holed. +-- Updatable ones will be overwritten with a CAFList cell, which points to a +-- black hole; +-- Single-entry ones have no fvs to plug, and we trust they don't form part +-- of a loop. + +blackHoleOnEntry ConInfo{} = False +blackHoleOnEntry (ClosureInfo { closureLFInfo = lf_info, closureSMRep = rep }) + | isStaticRep rep + = False -- Never black-hole a static closure + + | otherwise + = case lf_info of + LFReEntrant _ _ _ _ -> False + LFLetNoEscape _ -> False + LFThunk _ no_fvs updatable _ _ + -> if updatable + then not opt_OmitBlackHoling + else opt_DoTickyProfiling || not no_fvs + -- the former to catch double entry, + -- and the latter to plug space-leaks. KSW/SDM 1999-04. + + other -> panic "blackHoleOnEntry" -- Should never happen + +isStandardFormThunk :: LambdaFormInfo -> Bool +isStandardFormThunk (LFThunk _ _ _ (SelectorThunk _) _) = True +isStandardFormThunk (LFThunk _ _ _ (ApThunk _) _) = True +isStandardFormThunk other_lf_info = False + +isKnownFun :: LambdaFormInfo -> Bool +isKnownFun (LFReEntrant _ _ _ _) = True +isKnownFun (LFLetNoEscape _) = True +isKnownFun _ = False +\end{code} + +----------------------------------------------------------------------------- +SRT-related stuff + +\begin{code} +staticClosureNeedsLink :: ClosureInfo -> Bool +-- A static closure needs a link field to aid the GC when traversing +-- the static closure graph. But it only needs such a field if either +-- a) it has an SRT +-- b) it's a constructor with one or more pointer fields +-- In case (b), the constructor's fields themselves play the role +-- of the SRT. +staticClosureNeedsLink (ClosureInfo { closureSRT = srt }) + = needsSRT srt +staticClosureNeedsLink (ConInfo { closureSMRep = sm_rep, closureCon = con }) + = not (isNullaryRepDataCon con) && not_nocaf_constr + where + not_nocaf_constr = + case sm_rep of + GenericRep _ _ _ ConstrNoCaf -> False + _other -> True +\end{code} + +Avoiding generating entries and info tables +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +At present, for every function we generate all of the following, +just in case. But they aren't always all needed, as noted below: + +[NB1: all of this applies only to *functions*. Thunks always +have closure, info table, and entry code.] + +[NB2: All are needed if the function is *exported*, just to play safe.] + + +* Fast-entry code ALWAYS NEEDED + +* Slow-entry code + Needed iff (a) we have any un-saturated calls to the function + OR (b) the function is passed as an arg + OR (c) we're in the parallel world and the function has free vars + [Reason: in parallel world, we always enter functions + with free vars via the closure.] + +* The function closure + Needed iff (a) we have any un-saturated calls to the function + OR (b) the function is passed as an arg + OR (c) if the function has free vars (ie not top level) + + Why case (a) here? Because if the arg-satis check fails, + UpdatePAP stuffs a pointer to the function closure in the PAP. + [Could be changed; UpdatePAP could stuff in a code ptr instead, + but doesn't seem worth it.] + + [NB: these conditions imply that we might need the closure + without the slow-entry code. Here's how. + + f x y = let g w = ...x..y..w... + in + ...(g t)... + + Here we need a closure for g which contains x and y, + but since the calls are all saturated we just jump to the + fast entry point for g, with R1 pointing to the closure for g.] + + +* Standard info table + Needed iff (a) we have any un-saturated calls to the function + OR (b) the function is passed as an arg + OR (c) the function has free vars (ie not top level) + + NB. In the sequential world, (c) is only required so that the function closure has + an info table to point to, to keep the storage manager happy. + If (c) alone is true we could fake up an info table by choosing + one of a standard family of info tables, whose entry code just + bombs out. + + [NB In the parallel world (c) is needed regardless because + we enter functions with free vars via the closure.] + + If (c) is retained, then we'll sometimes generate an info table + (for storage mgr purposes) without slow-entry code. Then we need + to use an error label in the info table to substitute for the absent + slow entry code. + +\begin{code} +staticClosureRequired + :: Name + -> StgBinderInfo + -> LambdaFormInfo + -> Bool +staticClosureRequired binder bndr_info + (LFReEntrant top_level _ _ _) -- It's a function + = ASSERT( isTopLevel top_level ) + -- Assumption: it's a top-level, no-free-var binding + not (satCallsOnly bndr_info) + +staticClosureRequired binder other_binder_info other_lf_info = True +\end{code} + +%************************************************************************ +%* * +\subsection[ClosureInfo-misc-funs]{Misc functions about @ClosureInfo@, etc.} +%* * +%************************************************************************ + +\begin{code} + +isStaticClosure :: ClosureInfo -> Bool +isStaticClosure cl_info = isStaticRep (closureSMRep cl_info) + +closureUpdReqd :: ClosureInfo -> Bool +closureUpdReqd ClosureInfo{ closureLFInfo = lf_info } = lfUpdatable lf_info +closureUpdReqd ConInfo{} = False + +lfUpdatable :: LambdaFormInfo -> Bool +lfUpdatable (LFThunk _ _ upd _ _) = upd +lfUpdatable (LFBlackHole _) = True + -- Black-hole closures are allocated to receive the results of an + -- alg case with a named default... so they need to be updated. +lfUpdatable _ = False + +closureIsThunk :: ClosureInfo -> Bool +closureIsThunk ClosureInfo{ closureLFInfo = lf_info } = isLFThunk lf_info +closureIsThunk ConInfo{} = False + +closureSingleEntry :: ClosureInfo -> Bool +closureSingleEntry (ClosureInfo { closureLFInfo = LFThunk _ _ upd _ _}) = not upd +closureSingleEntry other_closure = False + +closureReEntrant :: ClosureInfo -> Bool +closureReEntrant (ClosureInfo { closureLFInfo = LFReEntrant _ _ _ _ }) = True +closureReEntrant other_closure = False + +isConstrClosure_maybe :: ClosureInfo -> Maybe DataCon +isConstrClosure_maybe (ConInfo { closureCon = data_con }) = Just data_con +isConstrClosure_maybe _ = Nothing + +closureFunInfo :: ClosureInfo -> Maybe (Int, ArgDescr) +closureFunInfo (ClosureInfo { closureLFInfo = LFReEntrant _ arity _ arg_desc}) + = Just (arity, arg_desc) +closureFunInfo _ + = Nothing +\end{code} + +\begin{code} +isToplevClosure :: ClosureInfo -> Bool +isToplevClosure (ClosureInfo { closureLFInfo = lf_info }) + = case lf_info of + LFReEntrant TopLevel _ _ _ -> True + LFThunk TopLevel _ _ _ _ -> True + other -> False +isToplevClosure _ = False +\end{code} + +Label generation. + +\begin{code} +infoTableLabelFromCI :: ClosureInfo -> CLabel +infoTableLabelFromCI (ClosureInfo { closureName = name, + closureLFInfo = lf_info, + closureSMRep = rep }) + = case lf_info of + LFBlackHole info -> info + + LFThunk _ _ upd_flag (SelectorThunk offset) _ -> + mkSelectorInfoLabel upd_flag offset + + LFThunk _ _ upd_flag (ApThunk arity) _ -> + mkApInfoTableLabel upd_flag arity + + LFThunk{} -> mkLocalInfoTableLabel name + + LFReEntrant _ _ _ _ -> mkLocalInfoTableLabel name + + other -> panic "infoTableLabelFromCI" + +infoTableLabelFromCI (ConInfo { closureCon = con, + closureSMRep = rep, + closureDllCon = dll }) + | isStaticRep rep = mkStaticInfoTableLabel name dll + | otherwise = mkConInfoTableLabel name dll + where + name = dataConName con + +-- ClosureInfo for a closure (as opposed to a constructor) is always local +closureLabelFromCI (ClosureInfo { closureName = nm }) = mkLocalClosureLabel nm +closureLabelFromCI _ = panic "closureLabelFromCI" + +-- thunkEntryLabel is a local help function, not exported. It's used from both +-- entryLabelFromCI and getCallMethod. + +thunkEntryLabel hmods thunk_id (ApThunk arity) is_updatable + = enterApLabel is_updatable arity +thunkEntryLabel hmods thunk_id (SelectorThunk offset) upd_flag + = enterSelectorLabel upd_flag offset +thunkEntryLabel hmods thunk_id _ is_updatable + = enterIdLabel hmods thunk_id + +enterApLabel is_updatable arity + | tablesNextToCode = mkApInfoTableLabel is_updatable arity + | otherwise = mkApEntryLabel is_updatable arity + +enterSelectorLabel upd_flag offset + | tablesNextToCode = mkSelectorInfoLabel upd_flag offset + | otherwise = mkSelectorEntryLabel upd_flag offset + +enterIdLabel hmods id + | tablesNextToCode = mkInfoTableLabel hmods id + | otherwise = mkEntryLabel hmods id + +enterLocalIdLabel id + | tablesNextToCode = mkLocalInfoTableLabel id + | otherwise = mkLocalEntryLabel id + +enterReturnPtLabel name + | tablesNextToCode = mkReturnInfoLabel name + | otherwise = mkReturnPtLabel name +\end{code} + + +We need a black-hole closure info to pass to @allocDynClosure@ when we +want to allocate the black hole on entry to a CAF. These are the only +ways to build an LFBlackHole, maintaining the invariant that it really +is a black hole and not something else. + +\begin{code} +cafBlackHoleClosureInfo (ClosureInfo { closureName = nm, + closureType = ty }) + = ClosureInfo { closureName = nm, + closureLFInfo = LFBlackHole mkCAFBlackHoleInfoTableLabel, + closureSMRep = BlackHoleRep, + closureSRT = NoC_SRT, + closureType = ty, + closureDescr = "" } +cafBlackHoleClosureInfo _ = panic "cafBlackHoleClosureInfo" + +seCafBlackHoleClosureInfo (ClosureInfo { closureName = nm, + closureType = ty }) + = ClosureInfo { closureName = nm, + closureLFInfo = LFBlackHole mkSECAFBlackHoleInfoTableLabel, + closureSMRep = BlackHoleRep, + closureSRT = NoC_SRT, + closureType = ty, + closureDescr = "" } +seCafBlackHoleClosureInfo _ = panic "seCafBlackHoleClosureInfo" +\end{code} + +%************************************************************************ +%* * +\subsection[ClosureInfo-Profiling-funs]{Misc functions about for profiling info.} +%* * +%************************************************************************ + +Profiling requires two pieces of information to be determined for +each closure's info table --- description and type. + +The description is stored directly in the @CClosureInfoTable@ when the +info table is built. + +The type is determined from the type information stored with the @Id@ +in the closure info using @closureTypeDescr@. + +\begin{code} +closureValDescr, closureTypeDescr :: ClosureInfo -> String +closureValDescr (ClosureInfo {closureDescr = descr}) + = descr +closureValDescr (ConInfo {closureCon = con}) + = occNameString (getOccName con) + +closureTypeDescr (ClosureInfo { closureType = ty }) + = getTyDescription ty +closureTypeDescr (ConInfo { closureCon = data_con }) + = occNameString (getOccName (dataConTyCon data_con)) + +getTyDescription :: Type -> String +getTyDescription ty + = case (tcSplitSigmaTy ty) of { (_, _, tau_ty) -> + case tau_ty of + TyVarTy _ -> "*" + AppTy fun _ -> getTyDescription fun + FunTy _ res -> '-' : '>' : fun_result res + TyConApp tycon _ -> getOccString tycon + NoteTy (FTVNote _) ty -> getTyDescription ty + PredTy sty -> getPredTyDescription sty + ForAllTy _ ty -> getTyDescription ty + } + where + fun_result (FunTy _ res) = '>' : fun_result res + fun_result other = getTyDescription other + +getPredTyDescription (ClassP cl tys) = getOccString cl +getPredTyDescription (IParam ip ty) = getOccString (ipNameName ip) +\end{code} + + |