2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[ClosureInfo]{Data structures which describe closures}
6 Much of the rationale for these things is in the ``details'' part of
10 #include "HsVersions.h"
13 ClosureInfo, LambdaFormInfo, SMRep, -- all abstract
18 mkClosureLFInfo, mkConLFInfo, mkSelectorLFInfo, mkVapLFInfo,
19 mkLFImported, mkLFArgument, mkLFLetNoEscape,
21 closureSize, closureHdrSize,
22 closureNonHdrSize, closureSizeWithoutFixedHdr,
23 closureGoodStuffSize, closurePtrsSize,
24 slopSize, fitsMinUpdSize,
26 layOutDynClosure, layOutDynCon, layOutStaticClosure,
27 layOutStaticNoFVClosure, layOutPhantomClosure,
30 nodeMustPointToIt, getEntryConvention,
33 staticClosureRequired,
34 slowFunEntryCodeRequired, funInfoTableRequired,
35 stdVapRequired, noUpdVapRequired,
37 closureId, infoTableLabelFromCI, fastLabelFromCI,
40 closureLFInfo, closureSMRep, closureUpdReqd,
41 closureSingleEntry, closureSemiTag, closureType,
42 closureReturnsUnboxedType, getStandardFormThunkInfo,
45 closureKind, closureTypeDescr, -- profiling
47 isStaticClosure, allocProfilingMsg,
51 dataConLiveness -- concurrency
55 #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201
56 IMPORT_DELOOPER(AbsCLoop) -- here for paranoia-checking
59 import AbsCSyn ( MagicId, node, mkLiveRegsMask,
60 {- GHC 0.29 only -} AbstractC, CAddrMode
65 import Constants ( mIN_UPD_SIZE, mIN_SIZE_NonUpdHeapObject,
66 mAX_SPEC_ALL_PTRS, mAX_SPEC_MIXED_FIELDS,
70 import CgRetConv ( assignRegs, dataReturnConvAlg,
71 DataReturnConvention(..)
73 import CLabel ( CLabel, mkStdEntryLabel, mkFastEntryLabel,
74 mkPhantomInfoTableLabel, mkInfoTableLabel,
75 mkConInfoTableLabel, mkStaticClosureLabel,
76 mkBlackHoleInfoTableLabel, mkVapInfoTableLabel,
77 mkStaticInfoTableLabel, mkStaticConEntryLabel,
78 mkConEntryLabel, mkClosureLabel, mkVapEntryLabel
80 import CmdLineOpts ( opt_SccProfilingOn, opt_ForConcurrent )
81 import HeapOffs ( intOff, addOff, totHdrSize, varHdrSize,
82 SYN_IE(VirtualHeapOffset), HeapOffset
84 import Id ( idType, getIdArity,
86 dataConTag, fIRST_TAG,
87 isDataCon, isNullaryDataCon, dataConTyCon,
88 isTupleCon, SYN_IE(DataCon),
89 GenId{-instance Eq-}, SYN_IE(Id)
91 import IdInfo ( ArityInfo(..) )
92 import Maybes ( maybeToBool )
93 import Name ( getOccString )
94 import Outputable ( PprStyle(..), Outputable(..) )
95 import PprType ( getTyDescription, GenType{-instance Outputable-} )
96 import Pretty --ToDo:rm
97 import PrelInfo ( maybeCharLikeTyCon, maybeIntLikeTyCon )
98 import PrimRep ( getPrimRepSize, separateByPtrFollowness, PrimRep )
99 import SMRep -- all of it
100 import TyCon ( TyCon{-instance NamedThing-} )
101 import Type ( isPrimType, splitFunTyExpandingDictsAndPeeking,
102 mkFunTys, maybeAppSpecDataTyConExpandingDicts,
105 import Util ( isIn, mapAccumL, panic, pprPanic, assertPanic )
108 The ``wrapper'' data type for closure information:
113 Id -- The thing bound to this closure
114 LambdaFormInfo -- info derivable from the *source*
115 SMRep -- representation used by storage manager
118 %************************************************************************
120 \subsection[ClosureInfo-OLD-DOC]{OLD DOCUMENTATION PROBABLY SUPERCEDED BY stg-details}
122 %************************************************************************
124 We can optimise the function-entry code as follows.
127 \item If the ``function'' is not updatable, we can jump directly to its
128 entry code, rather than indirecting via the info pointer in the
129 closure. (For updatable thunks we must go via the closure, in
130 case it has been updated.)
132 \item If the former bullet applies, and the application we are
133 compiling gives the function as many arguments as it needs, we
134 can jump to its fast-entry code. (This only applies if the
135 function has one or more args, because zero-arg closures have
138 \item If the function is a top-level non-constructor or imported, there
139 is no need to make Node point to its closure. In order for
140 this to be right, we need to ensure that:
142 \item If such closures are updatable then they push their
143 static address in the update frame, not Node. Actually
144 we create a black hole and push its address.
146 \item The arg satisfaction check should load Node before jumping to
149 \item Top-level constructor closures need careful handling. If we are to
150 jump direct to the constructor code, we must load Node first, even
151 though they are top-level. But if we go to their ``own''
152 standard-entry code (which loads Node and then jumps to the
153 constructor code) we don't need to load Node.
158 {\em Top level constructors (@mkStaticConEntryInfo@)}
161 x = {y,ys} \ {} Cons {y,ys} -- Std form constructor
164 x-closure: Cons-info-table, y-closure, ys-closure
166 x-entry: Node = x-closure; jump( Cons-entry )
168 x's EntryInfo in its own module:
170 Base-label = Cons -- Not x!!
172 ClosureClass = Constructor
175 So if x is entered, Node will be set up and
176 we'll jump direct to the Cons code.
178 x's EntryInfo in another module: (which may not know that x is a constructor)
180 Base-label = x -- Is x!!
181 NodeMustPoint = False -- All imported things have False
182 ClosureClass = non-committal
185 If x is entered, we'll jump to x-entry, which will set up Node
186 before jumping to the standard Cons code
188 {\em Top level non-constructors (@mkStaticEntryInfo@)}
193 For updatable thunks, x-entry must push an allocated BH in update frame, not Node.
195 For non-zero arity, arg satis check must load Node before jumping to
198 x's EntryInfo in its own module:
201 NodeMustPoint = False
202 ClosureClass = whatever
205 {\em Inner constructors (@mkConEntryInfo@)}
208 Base-label = Cons -- Not x!!
209 NodeMustPoint = True -- If its arity were zero, it would
210 -- have been lifted to top level
211 ClosureClass = Constructor
214 {\em Inner non-constructors (@mkEntryInfo@)}
218 NodeMustPoint = True -- If no free vars, would have been
219 -- lifted to top level
220 ClosureClass = whatever
229 NodeMustPoint = False
230 ClosureClass = whatever
234 THINK: we could omit making Node point to top-level constructors
235 of arity zero; but that might interact nastily with updates.
240 The info we need to import for imported things is:
243 data ImportInfo = UnknownImportInfo
244 | HnfImport Int -- Not updatable, arity given
245 -- Arity can be zero, for (eg) constrs
246 | UpdatableImport -- Must enter via the closure
249 ToDo: move this stuff???
252 mkStaticEntryInfo lbl cl_class
253 = MkEntryInfo lbl False cl_class
255 mkStaticConEntryInfo lbl
256 = MkEntryInfo lbl True ConstructorClosure
258 mkEntryInfo lbl cl_class
259 = MkEntryInfo lbl True cl_class
262 = MkEntryInfo lbl True ConstructorClosure
265 %************************************************************************
267 \subsection[ClosureInfo-datatypes]{Data types for closure information}
269 %************************************************************************
271 %************************************************************************
273 \subsubsection[LambdaFormInfo-datatype]{@LambdaFormInfo@: source-derivable info}
275 %************************************************************************
279 = LFReEntrant -- Reentrant closure; used for PAPs too
280 Bool -- True if top level
282 Bool -- True <=> no fvs
284 | LFCon -- Constructor
285 DataCon -- The constructor (may be specialised)
286 Bool -- True <=> zero arity
289 DataCon -- The tuple constructor (may be specialised)
290 Bool -- True <=> zero arity
292 | LFThunk -- Thunk (zero arity)
293 Bool -- True <=> top level
294 Bool -- True <=> no free vars
295 Bool -- True <=> updatable (i.e., *not* single-entry)
298 | LFArgument -- Used for function arguments. We know nothing about
299 -- this closure. Treat like updatable "LFThunk"...
301 | LFImported -- Used for imported things. We know nothing about this
302 -- closure. Treat like updatable "LFThunk"...
303 -- Imported things which we do know something about use
304 -- one of the other LF constructors (eg LFReEntrant for
307 | LFLetNoEscape -- See LetNoEscape module for precise description of
310 StgLiveVars-- list of variables live in the RHS of the let.
311 -- (ToDo: maybe not used)
313 | LFBlackHole -- Used for the closures allocated to hold the result
314 -- of a CAF. We want the target of the update frame to
315 -- be in the heap, so we make a black hole to hold it.
317 -- This last one is really only for completeness;
318 -- it isn't actually used for anything interesting
319 {- | LFIndirection -}
321 data StandardFormInfo -- Tells whether this thunk has one of a small number
324 = NonStandardThunk -- No, it isn't
328 DataCon -- Constructor
329 Int -- 0-origin offset of ak within the "goods" of constructor
330 -- (Recall that the a1,...,an may be laid out in the heap
331 -- in a non-obvious order.)
333 {- A SelectorThunk is of form
338 and the constructor is from a single-constr type.
339 If we can't convert the heap-offset of the selectee into an Int, e.g.,
340 it's "GEN_VHS+i", we just give up.
346 Bool -- True <=> the function is not top-level, so
347 -- must be stored in the thunk too
349 {- A VapThunk is of form
353 where f is a known function, with arity n
354 So for this thunk we can use the label for f's heap-entry
355 info table (generated when f's defn was dealt with),
356 rather than generating a one-off info table and entry code
361 mkLFArgument = LFArgument
362 mkLFBlackHole = LFBlackHole
363 mkLFLetNoEscape = LFLetNoEscape
365 mkLFImported :: Id -> LambdaFormInfo
367 = case getIdArity id of
368 ArityExactly 0 -> LFThunk True{-top-lev-} True{-no fvs-}
369 True{-updatable-} NonStandardThunk
370 ArityExactly n -> LFReEntrant True n True -- n > 0
371 other -> LFImported -- Not sure of exact arity
374 %************************************************************************
376 \subsection[ClosureInfo-construction]{Functions which build LFInfos}
378 %************************************************************************
380 @mkClosureLFInfo@ figures out the appropriate LFInfo for the closure.
383 mkClosureLFInfo :: Bool -- True of top level
385 -> UpdateFlag -- Update flag
389 mkClosureLFInfo top fvs upd_flag args@(_:_) -- Non-empty args
390 = LFReEntrant top (length args) (null fvs)
392 mkClosureLFInfo top fvs ReEntrant []
393 = LFReEntrant top 0 (null fvs)
395 mkClosureLFInfo top fvs upd_flag []
396 = LFThunk top (null fvs) (isUpdatable upd_flag) NonStandardThunk
398 isUpdatable ReEntrant = False
399 isUpdatable SingleEntry = False
400 isUpdatable Updatable = True
403 @mkConLFInfo@ is similar, for constructors.
406 mkConLFInfo :: DataCon -> LambdaFormInfo
409 = -- the isNullaryDataCon will do this: ASSERT(isDataCon con)
410 (if isTupleCon con then LFTuple else LFCon) con (isNullaryDataCon con)
412 mkSelectorLFInfo scrutinee con offset
413 = LFThunk False False True (SelectorThunk scrutinee con offset)
415 mkVapLFInfo fvs upd_flag fun_id args fun_in_vap
416 = LFThunk False (null fvs) (isUpdatable upd_flag) (VapThunk fun_id args fun_in_vap)
420 %************************************************************************
422 \subsection[ClosureInfo-sizes]{Functions about closure {\em sizes}}
424 %************************************************************************
427 closureSize :: ClosureInfo -> HeapOffset
428 closureSize cl_info@(MkClosureInfo _ _ sm_rep)
429 = totHdrSize sm_rep `addOff` (intOff (closureNonHdrSize cl_info))
431 closureSizeWithoutFixedHdr :: ClosureInfo -> HeapOffset
432 closureSizeWithoutFixedHdr cl_info@(MkClosureInfo _ _ sm_rep)
433 = varHdrSize sm_rep `addOff` (intOff (closureNonHdrSize cl_info))
435 closureHdrSize :: ClosureInfo -> HeapOffset
436 closureHdrSize (MkClosureInfo _ _ sm_rep)
439 closureNonHdrSize :: ClosureInfo -> Int
440 closureNonHdrSize cl_info@(MkClosureInfo _ lf_info sm_rep)
441 = tot_wds + computeSlopSize tot_wds sm_rep (closureUpdReqd cl_info) --ToDo: pass lf_info?
443 tot_wds = closureGoodStuffSize cl_info
445 closureGoodStuffSize :: ClosureInfo -> Int
446 closureGoodStuffSize (MkClosureInfo _ _ sm_rep)
447 = let (ptrs, nonptrs) = sizes_from_SMRep sm_rep
450 closurePtrsSize :: ClosureInfo -> Int
451 closurePtrsSize (MkClosureInfo _ _ sm_rep)
452 = let (ptrs, _) = sizes_from_SMRep sm_rep
456 sizes_from_SMRep (SpecialisedRep k ptrs nonptrs _) = (ptrs, nonptrs)
457 sizes_from_SMRep (GenericRep ptrs nonptrs _) = (ptrs, nonptrs)
458 sizes_from_SMRep (BigTupleRep ptrs) = (ptrs, 0)
459 sizes_from_SMRep (MuTupleRep ptrs) = (ptrs, 0)
460 sizes_from_SMRep (DataRep nonptrs) = (0, nonptrs)
461 sizes_from_SMRep BlackHoleRep = (0, 0)
462 sizes_from_SMRep (StaticRep ptrs nonptrs) = (ptrs, nonptrs)
464 sizes_from_SMRep PhantomRep = panic "sizes_from_SMRep: PhantomRep"
465 sizes_from_SMRep DynamicRep = panic "sizes_from_SMRep: DynamicRep"
470 fitsMinUpdSize :: ClosureInfo -> Bool
471 fitsMinUpdSize (MkClosureInfo _ _ BlackHoleRep) = True
472 fitsMinUpdSize cl_info = isSpecRep (closureSMRep cl_info) && closureNonHdrSize cl_info <= mIN_UPD_SIZE
475 Computing slop size. WARNING: this looks dodgy --- it has deep
476 knowledge of what the storage manager does with the various
482 Updateable closures must be @mIN_UPD_SIZE@.
485 Cons cell requires 2 words
487 Indirections require 1 word
489 Appels collector indirections 2 words
491 THEREFORE: @mIN_UPD_SIZE = 2@.
494 Collectable closures which are allocated in the heap
495 must be @mIN_SIZE_NonUpdHeapObject@.
497 Copying collector forward pointer requires 1 word
499 THEREFORE: @mIN_SIZE_NonUpdHeapObject = 1@
502 @SpecialisedRep@ closures closures may require slop:
505 @ConstantRep@ and @CharLikeRep@ closures always use the address of
506 a static closure. They are never allocated or
507 collected (eg hold forwarding pointer) hence never any slop.
510 @IntLikeRep@ are never updatable.
511 May need slop to be collected (as they will be size 1 or more
512 this probably has no affect)
515 @SpecRep@ may be updateable and will be collectable
518 @StaticRep@ may require slop if updatable. Non-updatable ones are OK.
521 @GenericRep@ closures will always be larger so never require slop.
524 ***** ToDo: keep an eye on this!
528 slopSize cl_info@(MkClosureInfo _ lf_info sm_rep)
529 = computeSlopSize (closureGoodStuffSize cl_info) sm_rep (closureUpdReqd cl_info)
531 computeSlopSize :: Int -> SMRep -> Bool -> Int
533 computeSlopSize tot_wds (SpecialisedRep ConstantRep _ _ _) _
535 computeSlopSize tot_wds (SpecialisedRep CharLikeRep _ _ _) _
538 computeSlopSize tot_wds (SpecialisedRep _ _ _ _) True -- Updatable
539 = max 0 (mIN_UPD_SIZE - tot_wds)
540 computeSlopSize tot_wds (StaticRep _ _) True -- Updatable
541 = max 0 (mIN_UPD_SIZE - tot_wds)
542 computeSlopSize tot_wds BlackHoleRep _ -- Updatable
543 = max 0 (mIN_UPD_SIZE - tot_wds)
545 computeSlopSize tot_wds (SpecialisedRep _ _ _ _) False -- Not updatable
546 = max 0 (mIN_SIZE_NonUpdHeapObject - tot_wds)
548 computeSlopSize tot_wds other_rep _ -- Any other rep
552 %************************************************************************
554 \subsection[layOutDynClosure]{Lay out a dynamic closure}
556 %************************************************************************
559 layOutDynClosure, layOutStaticClosure
560 :: Id -- STG identifier w/ which this closure assoc'd
561 -> (a -> PrimRep) -- function w/ which to be able to get a PrimRep
562 -> [a] -- the "things" being layed out
563 -> LambdaFormInfo -- what sort of closure it is
564 -> (ClosureInfo, -- info about the closure
565 [(a, VirtualHeapOffset)]) -- things w/ offsets pinned on them
567 layOutDynClosure name kind_fn things lf_info
568 = (MkClosureInfo name lf_info sm_rep,
571 (tot_wds, -- #ptr_wds + #nonptr_wds
573 things_w_offsets) = mkVirtHeapOffsets sm_rep kind_fn things
574 sm_rep = chooseDynSMRep lf_info tot_wds ptr_wds
576 layOutStaticClosure name kind_fn things lf_info
577 = (MkClosureInfo name lf_info (StaticRep ptr_wds (tot_wds - ptr_wds)),
580 (tot_wds, -- #ptr_wds + #nonptr_wds
582 things_w_offsets) = mkVirtHeapOffsets (StaticRep bot bot) kind_fn things
583 bot = panic "layoutStaticClosure"
585 layOutStaticNoFVClosure :: Id -> LambdaFormInfo -> ClosureInfo
586 layOutStaticNoFVClosure name lf_info
587 = MkClosureInfo name lf_info (StaticRep ptr_wds nonptr_wds)
589 -- I am very uncertain that this is right - it will show up when testing
590 -- my dynamic loading code. ADR
591 -- (If it's not right, we'll have to grab the kinds of the arguments from
596 layOutPhantomClosure :: Id -> LambdaFormInfo -> ClosureInfo
597 layOutPhantomClosure name lf_info = MkClosureInfo name lf_info PhantomRep
600 A wrapper for when used with data constructors:
602 layOutDynCon :: DataCon
605 -> (ClosureInfo, [(a,VirtualHeapOffset)])
607 layOutDynCon con kind_fn args
608 = ASSERT(isDataCon con)
609 layOutDynClosure con kind_fn args (mkConLFInfo con)
613 %************************************************************************
615 \subsection[SMreps]{Choosing SM reps}
617 %************************************************************************
622 -> Int -> Int -- Tot wds, ptr wds
625 chooseDynSMRep lf_info tot_wds ptr_wds
627 nonptr_wds = tot_wds - ptr_wds
629 updatekind = case lf_info of
630 LFThunk _ _ upd _ -> if upd then SMUpdatable else SMSingleEntry
631 LFBlackHole -> SMUpdatable
634 if (nonptr_wds == 0 && ptr_wds <= mAX_SPEC_ALL_PTRS)
635 || (tot_wds <= mAX_SPEC_MIXED_FIELDS)
636 || (ptr_wds == 0 && nonptr_wds <= mAX_SPEC_ALL_NONPTRS) then
638 spec_kind = case lf_info of
640 (LFTuple _ True) -> ConstantRep
642 (LFTuple _ _) -> SpecRep
644 (LFCon _ True) -> ConstantRep
646 (LFCon con _ ) -> if maybeToBool (maybeCharLikeTyCon tycon) then CharLikeRep
647 else if maybeToBool (maybeIntLikeTyCon tycon) then IntLikeRep
650 tycon = dataConTyCon con
654 SpecialisedRep spec_kind ptr_wds nonptr_wds updatekind
656 GenericRep ptr_wds nonptr_wds updatekind
660 %************************************************************************
662 \subsection[mkVirtHeapOffsets]{Assigning heap offsets in a closure}
664 %************************************************************************
666 @mkVirtHeapOffsets@ (the heap version) always returns boxed things with
667 smaller offsets than the unboxed things, and furthermore, the offsets in
671 mkVirtHeapOffsets :: SMRep -- Representation to be used by storage manager
672 -> (a -> PrimRep) -- To be able to grab kinds;
673 -- w/ a kind, we can find boxedness
674 -> [a] -- Things to make offsets for
675 -> (Int, -- *Total* number of words allocated
676 Int, -- Number of words allocated for *pointers*
677 [(a, VirtualHeapOffset)])
678 -- Things with their offsets from start of object
679 -- in order of increasing offset
681 -- First in list gets lowest offset, which is initial offset + 1.
683 mkVirtHeapOffsets sm_rep kind_fun things
684 = let (ptrs, non_ptrs) = separateByPtrFollowness kind_fun things
685 (wds_of_ptrs, ptrs_w_offsets) = mapAccumL computeOffset 0 ptrs
686 (tot_wds, non_ptrs_w_offsets) = mapAccumL computeOffset wds_of_ptrs non_ptrs
688 (tot_wds, wds_of_ptrs, ptrs_w_offsets ++ non_ptrs_w_offsets)
690 offset_of_first_word = totHdrSize sm_rep
691 computeOffset wds_so_far thing
692 = (wds_so_far + (getPrimRepSize . kind_fun) thing,
693 (thing, (offset_of_first_word `addOff` (intOff wds_so_far)))
697 %************************************************************************
699 \subsection[ClosureInfo-4-questions]{Four major questions about @ClosureInfo@}
701 %************************************************************************
703 Be sure to see the stg-details notes about these...
706 nodeMustPointToIt :: LambdaFormInfo -> FCode Bool
707 nodeMustPointToIt lf_info
709 do_profiling = opt_SccProfilingOn
712 LFReEntrant top arity no_fvs -> returnFC (
713 not no_fvs || -- Certainly if it has fvs we need to point to it
715 not top -- If it is not top level we will point to it
716 -- We can have a \r closure with no_fvs which
717 -- is not top level as special case cgRhsClosure
718 -- has been dissabled in favour of let floating
720 -- For lex_profiling we also access the cost centre for a
721 -- non-inherited function i.e. not top level
722 -- the not top case above ensures this is ok.
725 LFCon _ zero_arity -> returnFC True
726 LFTuple _ zero_arity -> returnFC True
728 -- Strictly speaking, the above two don't need Node to point
729 -- to it if the arity = 0. But this is a *really* unlikely
730 -- situation. If we know it's nil (say) and we are entering
731 -- it. Eg: let x = [] in x then we will certainly have inlined
732 -- x, since nil is a simple atom. So we gain little by not
733 -- having Node point to known zero-arity things. On the other
734 -- hand, we do lose something; Patrick's code for figuring out
735 -- when something has been updated but not entered relies on
736 -- having Node point to the result of an update. SLPJ
739 LFThunk _ no_fvs updatable NonStandardThunk
740 -> returnFC (updatable || not no_fvs || do_profiling)
742 -- For the non-updatable (single-entry case):
744 -- True if has fvs (in which case we need access to them, and we
745 -- should black-hole it)
746 -- or profiling (in which case we need to recover the cost centre
749 LFThunk _ no_fvs updatable some_standard_form_thunk
751 -- Node must point to any standard-form thunk.
754 -- generates a Vap thunk for (f y), and even if y is a global
755 -- variable we must still make Node point to the thunk before entering it
756 -- because that's what the standard-form code expects.
758 LFArgument -> returnFC True
759 LFImported -> returnFC True
760 LFBlackHole -> returnFC True
761 -- BH entry may require Node to point
763 LFLetNoEscape _ _ -> returnFC False
766 The entry conventions depend on the type of closure being entered,
767 whether or not it has free variables, and whether we're running
768 sequentially or in parallel.
770 \begin{tabular}{lllll}
771 Closure Characteristics & Parallel & Node Req'd & Argument Passing & Enter Via \\
772 Unknown & no & yes & stack & node \\
773 Known fun ($\ge$ 1 arg), no fvs & no & no & registers & fast entry (enough args) \\
774 \ & \ & \ & \ & slow entry (otherwise) \\
775 Known fun ($\ge$ 1 arg), fvs & no & yes & registers & fast entry (enough args) \\
776 0 arg, no fvs @\r,\s@ & no & no & n/a & direct entry \\
777 0 arg, no fvs @\u@ & no & yes & n/a & node \\
778 0 arg, fvs @\r,\s@ & no & yes & n/a & direct entry \\
779 0 arg, fvs @\u@ & no & yes & n/a & node \\
781 Unknown & yes & yes & stack & node \\
782 Known fun ($\ge$ 1 arg), no fvs & yes & no & registers & fast entry (enough args) \\
783 \ & \ & \ & \ & slow entry (otherwise) \\
784 Known fun ($\ge$ 1 arg), fvs & yes & yes & registers & node \\
785 0 arg, no fvs @\r,\s@ & yes & no & n/a & direct entry \\
786 0 arg, no fvs @\u@ & yes & yes & n/a & node \\
787 0 arg, fvs @\r,\s@ & yes & yes & n/a & node \\
788 0 arg, fvs @\u@ & yes & yes & n/a & node\\
791 When black-holing, single-entry closures could also be entered via node
792 (rather than directly) to catch double-entry.
796 = ViaNode -- The "normal" convention
798 | StdEntry CLabel -- Jump to this code, with args on stack
799 (Maybe CLabel) -- possibly setting infoptr to this
801 | DirectEntry -- Jump directly to code, with args in regs
802 CLabel -- The code label
804 [MagicId] -- Its register assignments (possibly empty)
806 getEntryConvention :: Id -- Function being applied
807 -> LambdaFormInfo -- Its info
808 -> [PrimRep] -- Available arguments
809 -> FCode EntryConvention
811 getEntryConvention id lf_info arg_kinds
812 = nodeMustPointToIt lf_info `thenFC` \ node_points ->
814 is_concurrent = opt_ForConcurrent
818 if (node_points && is_concurrent) then ViaNode else
822 LFReEntrant _ arity _ ->
823 if arity == 0 || (length arg_kinds) < arity then
824 StdEntry (mkStdEntryLabel id) Nothing
826 DirectEntry (mkFastEntryLabel id arity) arity arg_regs
828 (arg_regs, _) = assignRegs live_regs (take arity arg_kinds)
829 live_regs = if node_points then [node] else []
832 -> let itbl = if zero_arity then
833 mkPhantomInfoTableLabel con
835 mkConInfoTableLabel con
837 --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
838 StdEntry (mkConEntryLabel con) (Just itbl)
840 LFTuple tup zero_arity
841 -> --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
842 StdEntry (mkConEntryLabel tup) (Just (mkConInfoTableLabel tup))
844 LFThunk _ _ updatable std_form_info
847 else StdEntry (thunkEntryLabel id std_form_info updatable) Nothing
849 LFArgument -> ViaNode
850 LFImported -> ViaNode
851 LFBlackHole -> ViaNode -- Presumably the black hole has by now
852 -- been updated, but we don't know with
853 -- what, so we enter via Node
855 LFLetNoEscape arity _
856 -> ASSERT(arity == length arg_kinds)
857 DirectEntry (mkStdEntryLabel id) arity arg_regs
859 (arg_regs, _) = assignRegs live_regs arg_kinds
860 live_regs = if node_points then [node] else []
863 blackHoleOnEntry :: Bool -- No-black-holing flag
867 -- Static closures are never themselves black-holed.
868 -- Updatable ones will be overwritten with a CAFList cell, which points to a black hole;
869 -- Single-entry ones have no fvs to plug, and we trust they don't form part of a loop.
871 blackHoleOnEntry no_black_holing (MkClosureInfo _ _ (StaticRep _ _)) = False
873 blackHoleOnEntry no_black_holing (MkClosureInfo _ lf_info _)
875 LFReEntrant _ _ _ -> False
876 LFThunk _ no_fvs updatable _
878 then not no_black_holing
880 other -> panic "blackHoleOnEntry" -- Should never happen
882 getStandardFormThunkInfo
884 -> Maybe [StgArg] -- Nothing => not a standard-form thunk
885 -- Just atoms => a standard-form thunk with payload atoms
887 getStandardFormThunkInfo (LFThunk _ _ _ (SelectorThunk scrutinee _ _))
888 = --trace "Selector thunk: missed opportunity to save info table + code"
890 -- Just [StgVarArg scrutinee]
891 -- We can't save the info tbl + code until we have a way to generate
892 -- a fixed family thereof.
894 getStandardFormThunkInfo (LFThunk _ _ _ (VapThunk fun_id args fun_in_payload))
895 | fun_in_payload = Just (StgVarArg fun_id : args)
896 | otherwise = Just args
898 getStandardFormThunkInfo other_lf_info = Nothing
900 maybeSelectorInfo (MkClosureInfo _ (LFThunk _ _ _ (SelectorThunk _ con offset)) _) = Just (con,offset)
901 maybeSelectorInfo _ = Nothing
904 Avoiding generating entries and info tables
905 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
906 At present, for every function we generate all of the following,
907 just in case. But they aren't always all needed, as noted below:
909 [NB1: all of this applies only to *functions*. Thunks always
910 have closure, info table, and entry code.]
912 [NB2: All are needed if the function is *exported*, just to play safe.]
915 * Fast-entry code ALWAYS NEEDED
918 Needed iff (a) we have any un-saturated calls to the function
919 OR (b) the function is passed as an arg
920 OR (c) we're in the parallel world and the function has free vars
921 [Reason: in parallel world, we always enter functions
922 with free vars via the closure.]
924 * The function closure
925 Needed iff (a) we have any un-saturated calls to the function
926 OR (b) the function is passed as an arg
927 OR (c) if the function has free vars (ie not top level)
929 Why case (a) here? Because if the arg-satis check fails,
930 UpdatePAP stuffs a pointer to the function closure in the PAP.
931 [Could be changed; UpdatePAP could stuff in a code ptr instead,
932 but doesn't seem worth it.]
934 [NB: these conditions imply that we might need the closure
935 without the slow-entry code. Here's how.
937 f x y = let g w = ...x..y..w...
941 Here we need a closure for g which contains x and y,
942 but since the calls are all saturated we just jump to the
943 fast entry point for g, with R1 pointing to the closure for g.]
946 * Standard info table
947 Needed iff (a) we have any un-saturated calls to the function
948 OR (b) the function is passed as an arg
949 OR (c) the function has free vars (ie not top level)
951 NB. In the sequential world, (c) is only required so that the function closure has
952 an info table to point to, to keep the storage manager happy.
953 If (c) alone is true we could fake up an info table by choosing
954 one of a standard family of info tables, whose entry code just
957 [NB In the parallel world (c) is needed regardless because
958 we enter functions with free vars via the closure.]
960 If (c) is retained, then we'll sometimes generate an info table
961 (for storage mgr purposes) without slow-entry code. Then we need
962 to use an error label in the info table to substitute for the absent
965 * Standard vap-entry code
966 Standard vap-entry info table
967 Needed iff we have any updatable thunks of the standard vap-entry shape.
969 * Single-update vap-entry code
970 Single-update vap-entry info table
971 Needed iff we have any non-updatable thunks of the
972 standard vap-entry shape.
976 staticClosureRequired
981 staticClosureRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
982 (LFReEntrant top_level _ _) -- It's a function
983 = ASSERT( top_level ) -- Assumption: it's a top-level, no-free-var binding
984 arg_occ -- There's an argument occurrence
985 || unsat_occ -- There's an unsaturated call
986 || externallyVisibleId binder
988 staticClosureRequired binder other_binder_info other_lf_info = True
990 slowFunEntryCodeRequired -- Assumption: it's a function, not a thunk.
995 slowFunEntryCodeRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _) entry_conv
996 = arg_occ -- There's an argument occurrence
997 || unsat_occ -- There's an unsaturated call
998 || externallyVisibleId binder
999 || (case entry_conv of { DirectEntry _ _ _ -> False; other -> True })
1000 {- The last case deals with the parallel world; a function usually
1001 as a DirectEntry convention, but if it doesn't we must generate slow-entry code -}
1003 slowFunEntryCodeRequired binder NoStgBinderInfo _ = True
1005 funInfoTableRequired
1010 funInfoTableRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
1011 (LFReEntrant top_level _ _)
1013 || arg_occ -- There's an argument occurrence
1014 || unsat_occ -- There's an unsaturated call
1015 || externallyVisibleId binder
1017 funInfoTableRequired other_binder_info binder other_lf_info = True
1019 -- We need the vector-apply entry points for a function if
1020 -- there's a vector-apply occurrence in this module
1022 stdVapRequired, noUpdVapRequired :: StgBinderInfo -> Bool
1024 stdVapRequired binder_info
1025 = case binder_info of
1026 StgBinderInfo _ _ std_vap_occ _ _ -> std_vap_occ
1029 noUpdVapRequired binder_info
1030 = case binder_info of
1031 StgBinderInfo _ _ _ no_upd_vap_occ _ -> no_upd_vap_occ
1035 @lfArity@ extracts the arity of a function from its LFInfo
1038 {- Not needed any more
1040 lfArity_maybe (LFReEntrant _ arity _) = Just arity
1042 -- Removed SLPJ March 97. I don't believe these two;
1043 -- LFCon is used for construcor *applications*, not constructors!
1045 -- lfArity_maybe (LFCon con _) = Just (dataConArity con)
1046 -- lfArity_maybe (LFTuple con _) = Just (dataConArity con)
1048 lfArity_maybe other = Nothing
1052 %************************************************************************
1054 \subsection[ClosureInfo-misc-funs]{Misc functions about @ClosureInfo@, etc.}
1056 %************************************************************************
1060 isStaticClosure :: ClosureInfo -> Bool
1061 isStaticClosure (MkClosureInfo _ _ rep) = isStaticRep rep
1063 closureId :: ClosureInfo -> Id
1064 closureId (MkClosureInfo id _ _) = id
1066 closureSMRep :: ClosureInfo -> SMRep
1067 closureSMRep (MkClosureInfo _ _ sm_rep) = sm_rep
1069 closureLFInfo :: ClosureInfo -> LambdaFormInfo
1070 closureLFInfo (MkClosureInfo _ lf_info _) = lf_info
1072 closureUpdReqd :: ClosureInfo -> Bool
1074 closureUpdReqd (MkClosureInfo _ (LFThunk _ _ upd _) _) = upd
1075 closureUpdReqd (MkClosureInfo _ LFBlackHole _) = True
1076 -- Black-hole closures are allocated to receive the results of an
1077 -- alg case with a named default... so they need to be updated.
1078 closureUpdReqd other_closure = False
1080 closureSingleEntry :: ClosureInfo -> Bool
1082 closureSingleEntry (MkClosureInfo _ (LFThunk _ _ upd _) _) = not upd
1083 closureSingleEntry other_closure = False
1086 Note: @closureType@ returns appropriately specialised tycon and
1089 closureType :: ClosureInfo -> Maybe (TyCon, [Type], [Id])
1091 -- First, a turgid special case. When we are generating the
1092 -- standard code and info-table for Vaps (which is done when the function
1093 -- defn is encountered), we don't have a convenient Id to hand whose
1094 -- type is that of (f x y z). So we need to figure out the type
1095 -- rather than take it from the Id. The Id is probably just "f"!
1097 closureType (MkClosureInfo id (LFThunk _ _ _ (VapThunk fun_id args _)) _)
1098 = maybeAppSpecDataTyConExpandingDicts (fun_result_ty (length args) fun_id)
1100 closureType (MkClosureInfo id lf _) = maybeAppSpecDataTyConExpandingDicts (idType id)
1103 @closureReturnsUnboxedType@ is used to check whether a closure, {\em
1104 once it has eaten its arguments}, returns an unboxed type. For
1105 example, the closure for a function:
1109 returns an unboxed type. This is important when dealing with stack
1112 closureReturnsUnboxedType :: ClosureInfo -> Bool
1114 closureReturnsUnboxedType (MkClosureInfo fun_id (LFReEntrant _ arity _) _)
1115 = isPrimType (fun_result_ty arity fun_id)
1117 closureReturnsUnboxedType other_closure = False
1118 -- All non-function closures aren't functions,
1119 -- and hence are boxed, since they are heap alloc'd
1121 -- ToDo: need anything like this in Type.lhs?
1122 fun_result_ty arity id
1124 (arg_tys, res_ty) = splitFunTyExpandingDictsAndPeeking (idType id)
1126 -- ASSERT(arity >= 0 && length arg_tys >= arity)
1127 (if (arity >= 0 && length arg_tys >= arity) then (\x->x) else pprPanic "fun_result_ty:" (hsep [int arity, ppr PprShowAll id, ppr PprDebug (idType id)])) $
1128 mkFunTys (drop arity arg_tys) res_ty
1132 closureSemiTag :: ClosureInfo -> Int
1134 closureSemiTag (MkClosureInfo _ lf_info _)
1136 LFCon data_con _ -> dataConTag data_con - fIRST_TAG
1138 _ -> fromInteger oTHER_TAG
1142 isToplevClosure :: ClosureInfo -> Bool
1144 isToplevClosure (MkClosureInfo _ lf_info _)
1146 LFReEntrant top _ _ -> top
1147 LFThunk top _ _ _ -> top
1148 _ -> panic "ClosureInfo:isToplevClosure"
1154 fastLabelFromCI :: ClosureInfo -> CLabel
1155 fastLabelFromCI (MkClosureInfo id lf_info _)
1156 {- [SLPJ Changed March 97]
1157 (was ok, but is the only call to lfArity,
1158 and the id should guarantee to have the correct arity in it.
1160 = case lfArity_maybe lf_info of
1163 = case getIdArity id of
1164 ArityExactly arity -> mkFastEntryLabel id arity
1165 other -> pprPanic "fastLabelFromCI" (ppr PprDebug id)
1167 infoTableLabelFromCI :: ClosureInfo -> CLabel
1168 infoTableLabelFromCI (MkClosureInfo id lf_info rep)
1170 LFCon con _ -> mkConInfoPtr con rep
1171 LFTuple tup _ -> mkConInfoPtr tup rep
1173 LFBlackHole -> mkBlackHoleInfoTableLabel
1175 LFThunk _ _ upd_flag (VapThunk fun_id args _) -> mkVapInfoTableLabel fun_id upd_flag
1176 -- Use the standard vap info table
1177 -- for the function, rather than a one-off one
1178 -- for this particular closure
1180 {- For now, we generate individual info table and entry code for selector thunks,
1181 so their info table should be labelled in the standard way.
1182 The only special thing about them is that the info table has a field which
1183 tells the GC that it really is a selector.
1185 Later, perhaps, we'll have some standard RTS code for selector-thunk info tables,
1186 in which case this line will spring back to life.
1188 LFThunk _ _ upd_flag (SelectorThunk _ _ offset) -> mkSelectorInfoTableLabel upd_flag offset
1189 -- Ditto for selectors
1192 other -> {-NO: if isStaticRep rep
1193 then mkStaticInfoTableLabel id
1194 else -} mkInfoTableLabel id
1196 mkConInfoPtr :: Id -> SMRep -> CLabel
1197 mkConInfoPtr con rep
1198 = ASSERT(isDataCon con)
1200 PhantomRep -> mkPhantomInfoTableLabel con
1201 StaticRep _ _ -> mkStaticInfoTableLabel con
1202 _ -> mkConInfoTableLabel con
1204 mkConEntryPtr :: Id -> SMRep -> CLabel
1205 mkConEntryPtr con rep
1206 = ASSERT(isDataCon con)
1208 StaticRep _ _ -> mkStaticConEntryLabel con
1209 _ -> mkConEntryLabel con
1212 closureLabelFromCI (MkClosureInfo id _ rep)
1214 = mkStaticClosureLabel id
1215 -- This case catches those pesky static closures for nullary constructors
1217 closureLabelFromCI (MkClosureInfo id _ other_rep) = mkClosureLabel id
1219 entryLabelFromCI :: ClosureInfo -> CLabel
1220 entryLabelFromCI (MkClosureInfo id lf_info rep)
1222 LFThunk _ _ upd_flag std_form_info -> thunkEntryLabel id std_form_info upd_flag
1223 LFCon con _ -> mkConEntryPtr con rep
1224 LFTuple tup _ -> mkConEntryPtr tup rep
1225 other -> mkStdEntryLabel id
1227 -- thunkEntryLabel is a local help function, not exported. It's used from both
1228 -- entryLabelFromCI and getEntryConvention.
1229 -- I don't think it needs to deal with the SelectorThunk case
1230 -- Well, it's falling over now, so I've made it deal with it. (JSM)
1232 thunkEntryLabel thunk_id (VapThunk fun_id args _) is_updatable
1233 = mkVapEntryLabel fun_id is_updatable
1234 thunkEntryLabel thunk_id _ is_updatable
1235 = mkStdEntryLabel thunk_id
1239 allocProfilingMsg :: ClosureInfo -> FAST_STRING
1241 allocProfilingMsg (MkClosureInfo _ lf_info _)
1243 LFReEntrant _ _ _ -> SLIT("ALLOC_FUN")
1244 LFCon _ _ -> SLIT("ALLOC_CON")
1245 LFTuple _ _ -> SLIT("ALLOC_CON")
1246 LFThunk _ _ _ _ -> SLIT("ALLOC_THK")
1247 LFBlackHole -> SLIT("ALLOC_BH")
1248 LFImported -> panic "ALLOC_IMP"
1251 We need a black-hole closure info to pass to @allocDynClosure@ when we
1252 want to allocate the black hole on entry to a CAF.
1255 blackHoleClosureInfo (MkClosureInfo id _ _)
1256 = MkClosureInfo id LFBlackHole BlackHoleRep
1259 The register liveness when returning from a constructor. For
1260 simplicity, we claim just [node] is live for all but PhantomRep's. In
1261 truth, this means that non-constructor info tables also claim node,
1262 but since their liveness information is never used, we don't care.
1265 dataConLiveness (MkClosureInfo con _ PhantomRep)
1266 = case (dataReturnConvAlg con) of
1267 ReturnInRegs regs -> mkLiveRegsMask regs
1268 ReturnInHeap -> panic "dataConLiveness:PhantomRep in heap???"
1270 dataConLiveness _ = mkLiveRegsMask [node]
1273 %************************************************************************
1275 \subsection[ClosureInfo-Profiling-funs]{Misc functions about for profiling info.}
1277 %************************************************************************
1279 Profiling requires three pices of information to be determined for
1280 each closure's info table --- kind, description and type.
1282 The description is stored directly in the @CClosureInfoTable@ when the
1283 info table is built.
1285 The kind is determined from the @LambdaForm@ stored in the closure
1286 info using @closureKind@.
1288 The type is determined from the type information stored with the @Id@
1289 in the closure info using @closureTypeDescr@.
1292 closureKind :: ClosureInfo -> String
1294 closureKind (MkClosureInfo _ lf _)
1296 LFReEntrant _ n _ -> if n > 0 then "FN_K" else "THK_K"
1297 LFCon _ _ -> "CON_K"
1298 LFTuple _ _ -> "CON_K"
1299 LFThunk _ _ _ _ -> "THK_K"
1300 LFBlackHole -> "THK_K" -- consider BHs as thunks for the moment... (ToDo?)
1301 LFImported -> panic "IMP_KIND"
1303 closureTypeDescr :: ClosureInfo -> String
1304 closureTypeDescr (MkClosureInfo id lf _)
1305 = if (isDataCon id) then -- DataCon has function types
1306 getOccString (dataConTyCon id) -- We want the TyCon not the ->
1308 getTyDescription (idType id)