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
11 ClosureInfo, LambdaFormInfo, SMRep, -- all abstract
16 mkClosureLFInfo, mkConLFInfo, mkSelectorLFInfo, mkVapLFInfo,
17 mkLFImported, mkLFArgument, mkLFLetNoEscape,
20 closureSize, closureHdrSize,
21 closureNonHdrSize, closureSizeWithoutFixedHdr,
22 closureGoodStuffSize, closurePtrsSize,
23 slopSize, fitsMinUpdSize,
25 layOutDynClosure, layOutDynCon, layOutStaticClosure,
26 layOutStaticNoFVClosure, layOutPhantomClosure,
29 nodeMustPointToIt, getEntryConvention,
30 FCode, CgInfoDownwards, CgState,
34 staticClosureRequired,
35 slowFunEntryCodeRequired, funInfoTableRequired,
36 stdVapRequired, noUpdVapRequired,
39 closureId, infoTableLabelFromCI, fastLabelFromCI,
42 closureLFInfo, closureSMRep, closureUpdReqd,
43 closureSingleEntry, closureSemiTag, closureType,
44 closureReturnsUnpointedType, getStandardFormThunkInfo,
48 closureKind, closureTypeDescr, -- profiling
50 isStaticClosure, allocProfilingMsg,
54 dataConLiveness -- concurrency
57 #include "HsVersions.h"
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 VirtualHeapOffset, HeapOffset
84 import Id ( idType, getIdArity,
86 dataConTag, fIRST_TAG,
87 isDataCon, isNullaryDataCon, dataConTyCon,
89 GenId{-instance Eq-}, Id
91 import IdInfo ( ArityInfo(..) )
92 import Maybes ( maybeToBool )
93 import Name ( getOccString )
94 import PprType ( getTyDescription )
95 import PrelInfo ( maybeCharLikeCon, maybeIntLikeCon )
96 import PrimRep ( getPrimRepSize, separateByPtrFollowness, PrimRep )
97 import SMRep -- all of it
98 import TyCon ( TyCon, isNewTyCon )
99 import Type ( isUnpointedType, splitForAllTys, splitFunTys, mkFunTys,
100 splitAlgTyConApp_maybe, applyTys,
103 import Util ( isIn, mapAccumL )
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 maybeCharLikeCon con then CharLikeRep
647 else if maybeIntLikeCon con then IntLikeRep
652 SpecialisedRep spec_kind ptr_wds nonptr_wds updatekind
654 GenericRep ptr_wds nonptr_wds updatekind
658 %************************************************************************
660 \subsection[mkVirtHeapOffsets]{Assigning heap offsets in a closure}
662 %************************************************************************
664 @mkVirtHeapOffsets@ (the heap version) always returns boxed things with
665 smaller offsets than the unboxed things, and furthermore, the offsets in
669 mkVirtHeapOffsets :: SMRep -- Representation to be used by storage manager
670 -> (a -> PrimRep) -- To be able to grab kinds;
671 -- w/ a kind, we can find boxedness
672 -> [a] -- Things to make offsets for
673 -> (Int, -- *Total* number of words allocated
674 Int, -- Number of words allocated for *pointers*
675 [(a, VirtualHeapOffset)])
676 -- Things with their offsets from start of object
677 -- in order of increasing offset
679 -- First in list gets lowest offset, which is initial offset + 1.
681 mkVirtHeapOffsets sm_rep kind_fun things
682 = let (ptrs, non_ptrs) = separateByPtrFollowness kind_fun things
683 (wds_of_ptrs, ptrs_w_offsets) = mapAccumL computeOffset 0 ptrs
684 (tot_wds, non_ptrs_w_offsets) = mapAccumL computeOffset wds_of_ptrs non_ptrs
686 (tot_wds, wds_of_ptrs, ptrs_w_offsets ++ non_ptrs_w_offsets)
688 offset_of_first_word = totHdrSize sm_rep
689 computeOffset wds_so_far thing
690 = (wds_so_far + (getPrimRepSize . kind_fun) thing,
691 (thing, (offset_of_first_word `addOff` (intOff wds_so_far)))
695 %************************************************************************
697 \subsection[ClosureInfo-4-questions]{Four major questions about @ClosureInfo@}
699 %************************************************************************
701 Be sure to see the stg-details notes about these...
704 nodeMustPointToIt :: LambdaFormInfo -> FCode Bool
705 nodeMustPointToIt lf_info
707 do_profiling = opt_SccProfilingOn
710 LFReEntrant top arity no_fvs -> returnFC (
711 not no_fvs || -- Certainly if it has fvs we need to point to it
713 not top -- If it is not top level we will point to it
714 -- We can have a \r closure with no_fvs which
715 -- is not top level as special case cgRhsClosure
716 -- has been dissabled in favour of let floating
718 -- For lex_profiling we also access the cost centre for a
719 -- non-inherited function i.e. not top level
720 -- the not top case above ensures this is ok.
723 LFCon _ zero_arity -> returnFC True
724 LFTuple _ zero_arity -> returnFC True
726 -- Strictly speaking, the above two don't need Node to point
727 -- to it if the arity = 0. But this is a *really* unlikely
728 -- situation. If we know it's nil (say) and we are entering
729 -- it. Eg: let x = [] in x then we will certainly have inlined
730 -- x, since nil is a simple atom. So we gain little by not
731 -- having Node point to known zero-arity things. On the other
732 -- hand, we do lose something; Patrick's code for figuring out
733 -- when something has been updated but not entered relies on
734 -- having Node point to the result of an update. SLPJ
737 LFThunk _ no_fvs updatable NonStandardThunk
738 -> returnFC (updatable || not no_fvs || do_profiling)
740 -- For the non-updatable (single-entry case):
742 -- True if has fvs (in which case we need access to them, and we
743 -- should black-hole it)
744 -- or profiling (in which case we need to recover the cost centre
747 LFThunk _ no_fvs updatable some_standard_form_thunk
749 -- Node must point to any standard-form thunk.
752 -- generates a Vap thunk for (f y), and even if y is a global
753 -- variable we must still make Node point to the thunk before entering it
754 -- because that's what the standard-form code expects.
756 LFArgument -> returnFC True
757 LFImported -> returnFC True
758 LFBlackHole -> returnFC True
759 -- BH entry may require Node to point
761 LFLetNoEscape _ _ -> returnFC False
764 The entry conventions depend on the type of closure being entered,
765 whether or not it has free variables, and whether we're running
766 sequentially or in parallel.
768 \begin{tabular}{lllll}
769 Closure Characteristics & Parallel & Node Req'd & Argument Passing & Enter Via \\
770 Unknown & no & yes & stack & node \\
771 Known fun ($\ge$ 1 arg), no fvs & no & no & registers & fast entry (enough args) \\
772 \ & \ & \ & \ & slow entry (otherwise) \\
773 Known fun ($\ge$ 1 arg), fvs & no & yes & registers & fast entry (enough args) \\
774 0 arg, no fvs @\r,\s@ & no & no & n/a & direct entry \\
775 0 arg, no fvs @\u@ & no & yes & n/a & node \\
776 0 arg, fvs @\r,\s@ & no & yes & n/a & direct entry \\
777 0 arg, fvs @\u@ & no & yes & n/a & node \\
779 Unknown & yes & yes & stack & node \\
780 Known fun ($\ge$ 1 arg), no fvs & yes & no & registers & fast entry (enough args) \\
781 \ & \ & \ & \ & slow entry (otherwise) \\
782 Known fun ($\ge$ 1 arg), fvs & yes & yes & registers & node \\
783 0 arg, no fvs @\r,\s@ & yes & no & n/a & direct entry \\
784 0 arg, no fvs @\u@ & yes & yes & n/a & node \\
785 0 arg, fvs @\r,\s@ & yes & yes & n/a & node \\
786 0 arg, fvs @\u@ & yes & yes & n/a & node\\
789 When black-holing, single-entry closures could also be entered via node
790 (rather than directly) to catch double-entry.
794 = ViaNode -- The "normal" convention
796 | StdEntry CLabel -- Jump to this code, with args on stack
797 (Maybe CLabel) -- possibly setting infoptr to this
799 | DirectEntry -- Jump directly to code, with args in regs
800 CLabel -- The code label
802 [MagicId] -- Its register assignments (possibly empty)
804 getEntryConvention :: Id -- Function being applied
805 -> LambdaFormInfo -- Its info
806 -> [PrimRep] -- Available arguments
807 -> FCode EntryConvention
809 getEntryConvention id lf_info arg_kinds
810 = nodeMustPointToIt lf_info `thenFC` \ node_points ->
812 is_concurrent = opt_ForConcurrent
816 if (node_points && is_concurrent) then ViaNode else
820 LFReEntrant _ arity _ ->
821 if arity == 0 || (length arg_kinds) < arity then
822 StdEntry (mkStdEntryLabel id) Nothing
824 DirectEntry (mkFastEntryLabel id arity) arity arg_regs
826 (arg_regs, _) = assignRegs live_regs (take arity arg_kinds)
827 live_regs = if node_points then [node] else []
830 -> let itbl = if zero_arity then
831 mkPhantomInfoTableLabel con
833 mkConInfoTableLabel con
835 --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
836 StdEntry (mkConEntryLabel con) (Just itbl)
838 LFTuple tup zero_arity
839 -> --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
840 StdEntry (mkConEntryLabel tup) (Just (mkConInfoTableLabel tup))
842 LFThunk _ _ updatable std_form_info
845 else StdEntry (thunkEntryLabel id std_form_info updatable) Nothing
847 LFArgument -> ViaNode
848 LFImported -> ViaNode
849 LFBlackHole -> ViaNode -- Presumably the black hole has by now
850 -- been updated, but we don't know with
851 -- what, so we enter via Node
853 LFLetNoEscape arity _
854 -> ASSERT(arity == length arg_kinds)
855 DirectEntry (mkStdEntryLabel id) arity arg_regs
857 (arg_regs, _) = assignRegs live_regs arg_kinds
858 live_regs = if node_points then [node] else []
861 blackHoleOnEntry :: Bool -- No-black-holing flag
865 -- Static closures are never themselves black-holed.
866 -- Updatable ones will be overwritten with a CAFList cell, which points to a black hole;
867 -- Single-entry ones have no fvs to plug, and we trust they don't form part of a loop.
869 blackHoleOnEntry no_black_holing (MkClosureInfo _ _ (StaticRep _ _)) = False
871 blackHoleOnEntry no_black_holing (MkClosureInfo _ lf_info _)
873 LFReEntrant _ _ _ -> False
874 LFThunk _ no_fvs updatable _
876 then not no_black_holing
878 other -> panic "blackHoleOnEntry" -- Should never happen
880 getStandardFormThunkInfo
882 -> Maybe [StgArg] -- Nothing => not a standard-form thunk
883 -- Just atoms => a standard-form thunk with payload atoms
885 getStandardFormThunkInfo (LFThunk _ _ _ (SelectorThunk scrutinee _ _))
886 = --trace "Selector thunk: missed opportunity to save info table + code"
888 -- Just [StgVarArg scrutinee]
889 -- We can't save the info tbl + code until we have a way to generate
890 -- a fixed family thereof.
892 getStandardFormThunkInfo (LFThunk _ _ _ (VapThunk fun_id args fun_in_payload))
893 | fun_in_payload = Just (StgVarArg fun_id : args)
894 | otherwise = Just args
896 getStandardFormThunkInfo other_lf_info = Nothing
898 maybeSelectorInfo (MkClosureInfo _ (LFThunk _ _ _ (SelectorThunk _ con offset)) _) = Just (con,offset)
899 maybeSelectorInfo _ = Nothing
902 Avoiding generating entries and info tables
903 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
904 At present, for every function we generate all of the following,
905 just in case. But they aren't always all needed, as noted below:
907 [NB1: all of this applies only to *functions*. Thunks always
908 have closure, info table, and entry code.]
910 [NB2: All are needed if the function is *exported*, just to play safe.]
913 * Fast-entry code ALWAYS NEEDED
916 Needed iff (a) we have any un-saturated calls to the function
917 OR (b) the function is passed as an arg
918 OR (c) we're in the parallel world and the function has free vars
919 [Reason: in parallel world, we always enter functions
920 with free vars via the closure.]
922 * The function closure
923 Needed iff (a) we have any un-saturated calls to the function
924 OR (b) the function is passed as an arg
925 OR (c) if the function has free vars (ie not top level)
927 Why case (a) here? Because if the arg-satis check fails,
928 UpdatePAP stuffs a pointer to the function closure in the PAP.
929 [Could be changed; UpdatePAP could stuff in a code ptr instead,
930 but doesn't seem worth it.]
932 [NB: these conditions imply that we might need the closure
933 without the slow-entry code. Here's how.
935 f x y = let g w = ...x..y..w...
939 Here we need a closure for g which contains x and y,
940 but since the calls are all saturated we just jump to the
941 fast entry point for g, with R1 pointing to the closure for g.]
944 * Standard info table
945 Needed iff (a) we have any un-saturated calls to the function
946 OR (b) the function is passed as an arg
947 OR (c) the function has free vars (ie not top level)
949 NB. In the sequential world, (c) is only required so that the function closure has
950 an info table to point to, to keep the storage manager happy.
951 If (c) alone is true we could fake up an info table by choosing
952 one of a standard family of info tables, whose entry code just
955 [NB In the parallel world (c) is needed regardless because
956 we enter functions with free vars via the closure.]
958 If (c) is retained, then we'll sometimes generate an info table
959 (for storage mgr purposes) without slow-entry code. Then we need
960 to use an error label in the info table to substitute for the absent
963 * Standard vap-entry code
964 Standard vap-entry info table
965 Needed iff we have any updatable thunks of the standard vap-entry shape.
967 * Single-update vap-entry code
968 Single-update vap-entry info table
969 Needed iff we have any non-updatable thunks of the
970 standard vap-entry shape.
974 staticClosureRequired
979 staticClosureRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
980 (LFReEntrant top_level _ _) -- It's a function
981 = ASSERT( top_level ) -- Assumption: it's a top-level, no-free-var binding
982 arg_occ -- There's an argument occurrence
983 || unsat_occ -- There's an unsaturated call
984 || externallyVisibleId binder
986 staticClosureRequired binder other_binder_info other_lf_info = True
988 slowFunEntryCodeRequired -- Assumption: it's a function, not a thunk.
993 slowFunEntryCodeRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _) entry_conv
994 = arg_occ -- There's an argument occurrence
995 || unsat_occ -- There's an unsaturated call
996 || externallyVisibleId binder
997 || (case entry_conv of { DirectEntry _ _ _ -> False; other -> True })
998 {- The last case deals with the parallel world; a function usually
999 as a DirectEntry convention, but if it doesn't we must generate slow-entry code -}
1001 slowFunEntryCodeRequired binder NoStgBinderInfo _ = True
1003 funInfoTableRequired
1008 funInfoTableRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
1009 (LFReEntrant top_level _ _)
1011 || arg_occ -- There's an argument occurrence
1012 || unsat_occ -- There's an unsaturated call
1013 || externallyVisibleId binder
1015 funInfoTableRequired other_binder_info binder other_lf_info = True
1017 -- We need the vector-apply entry points for a function if
1018 -- there's a vector-apply occurrence in this module
1020 stdVapRequired, noUpdVapRequired :: StgBinderInfo -> Bool
1022 stdVapRequired binder_info
1023 = case binder_info of
1024 StgBinderInfo _ _ std_vap_occ _ _ -> std_vap_occ
1027 noUpdVapRequired binder_info
1028 = case binder_info of
1029 StgBinderInfo _ _ _ no_upd_vap_occ _ -> no_upd_vap_occ
1033 @lfArity@ extracts the arity of a function from its LFInfo
1036 {- Not needed any more
1038 lfArity_maybe (LFReEntrant _ arity _) = Just arity
1040 -- Removed SLPJ March 97. I don't believe these two;
1041 -- LFCon is used for construcor *applications*, not constructors!
1043 -- lfArity_maybe (LFCon con _) = Just (dataConArity con)
1044 -- lfArity_maybe (LFTuple con _) = Just (dataConArity con)
1046 lfArity_maybe other = Nothing
1050 %************************************************************************
1052 \subsection[ClosureInfo-misc-funs]{Misc functions about @ClosureInfo@, etc.}
1054 %************************************************************************
1058 isStaticClosure :: ClosureInfo -> Bool
1059 isStaticClosure (MkClosureInfo _ _ rep) = isStaticRep rep
1061 closureId :: ClosureInfo -> Id
1062 closureId (MkClosureInfo id _ _) = id
1064 closureSMRep :: ClosureInfo -> SMRep
1065 closureSMRep (MkClosureInfo _ _ sm_rep) = sm_rep
1067 closureLFInfo :: ClosureInfo -> LambdaFormInfo
1068 closureLFInfo (MkClosureInfo _ lf_info _) = lf_info
1070 closureUpdReqd :: ClosureInfo -> Bool
1072 closureUpdReqd (MkClosureInfo _ (LFThunk _ _ upd _) _) = upd
1073 closureUpdReqd (MkClosureInfo _ LFBlackHole _) = True
1074 -- Black-hole closures are allocated to receive the results of an
1075 -- alg case with a named default... so they need to be updated.
1076 closureUpdReqd other_closure = False
1078 closureSingleEntry :: ClosureInfo -> Bool
1080 closureSingleEntry (MkClosureInfo _ (LFThunk _ _ upd _) _) = not upd
1081 closureSingleEntry other_closure = False
1084 Note: @closureType@ returns appropriately specialised tycon and
1087 closureType :: ClosureInfo -> Maybe (TyCon, [Type], [Id])
1089 -- First, a turgid special case. When we are generating the
1090 -- standard code and info-table for Vaps (which is done when the function
1091 -- defn is encountered), we don't have a convenient Id to hand whose
1092 -- type is that of (f x y z). So we need to figure out the type
1093 -- rather than take it from the Id. The Id is probably just "f"!
1095 closureType (MkClosureInfo id (LFThunk _ _ _ (VapThunk fun_id args _)) _)
1096 = splitAlgTyConApp_maybe (fun_result_ty (length args) (idType fun_id))
1098 closureType (MkClosureInfo id lf _) = splitAlgTyConApp_maybe (idType id)
1101 @closureReturnsUnpointedType@ is used to check whether a closure, {\em
1102 once it has eaten its arguments}, returns an unboxed type. For
1103 example, the closure for a function:
1107 returns an unboxed type. This is important when dealing with stack
1110 closureReturnsUnpointedType :: ClosureInfo -> Bool
1112 closureReturnsUnpointedType (MkClosureInfo fun_id (LFReEntrant _ arity _) _)
1113 = isUnpointedType (fun_result_ty arity (idType fun_id))
1115 closureReturnsUnpointedType other_closure = False
1116 -- All non-function closures aren't functions,
1117 -- and hence are boxed, since they are heap alloc'd
1119 -- fun_result_ty is a disgusting little bit of code that finds the result
1120 -- type of a function application. It looks "through" new types.
1121 -- We don't have type args available any more, so we are pretty cavilier,
1122 -- and quite possibly plain wrong. Let's hope it doesn't matter if we are!
1124 fun_result_ty arity ty
1125 | arity <= n_arg_tys
1126 = mkFunTys (drop arity arg_tys) res_ty
1129 = case splitAlgTyConApp_maybe res_ty of
1130 Nothing -> pprPanic "fun_result_ty:" (hsep [int arity,
1133 Just (tycon, tycon_arg_tys, [con]) | isNewTyCon tycon
1134 -> fun_result_ty (arity - n_arg_tys) rep_ty
1136 ([rep_ty], _) = splitFunTys (applyTys (idType con) tycon_arg_tys)
1137 Just (_,_,cons) -> trace (showSDoc (ppr ty) ++ showSDoc(ppr cons)) $ panic "fun_result_ty"
1139 (_, rho_ty) = splitForAllTys ty
1140 (arg_tys, res_ty) = splitFunTys rho_ty
1141 n_arg_tys = length arg_tys
1145 closureSemiTag :: ClosureInfo -> Int
1147 closureSemiTag (MkClosureInfo _ lf_info _)
1149 LFCon data_con _ -> dataConTag data_con - fIRST_TAG
1151 _ -> fromInteger oTHER_TAG
1155 isToplevClosure :: ClosureInfo -> Bool
1157 isToplevClosure (MkClosureInfo _ lf_info _)
1159 LFReEntrant top _ _ -> top
1160 LFThunk top _ _ _ -> top
1161 _ -> panic "ClosureInfo:isToplevClosure"
1167 fastLabelFromCI :: ClosureInfo -> CLabel
1168 fastLabelFromCI (MkClosureInfo id lf_info _)
1169 {- [SLPJ Changed March 97]
1170 (was ok, but is the only call to lfArity,
1171 and the id should guarantee to have the correct arity in it.
1173 = case lfArity_maybe lf_info of
1176 = case getIdArity id of
1177 ArityExactly arity -> mkFastEntryLabel id arity
1178 other -> pprPanic "fastLabelFromCI" (ppr id)
1180 infoTableLabelFromCI :: ClosureInfo -> CLabel
1181 infoTableLabelFromCI (MkClosureInfo id lf_info rep)
1183 LFCon con _ -> mkConInfoPtr con rep
1184 LFTuple tup _ -> mkConInfoPtr tup rep
1186 LFBlackHole -> mkBlackHoleInfoTableLabel
1188 LFThunk _ _ upd_flag (VapThunk fun_id args _) -> mkVapInfoTableLabel fun_id upd_flag
1189 -- Use the standard vap info table
1190 -- for the function, rather than a one-off one
1191 -- for this particular closure
1193 {- For now, we generate individual info table and entry code for selector thunks,
1194 so their info table should be labelled in the standard way.
1195 The only special thing about them is that the info table has a field which
1196 tells the GC that it really is a selector.
1198 Later, perhaps, we'll have some standard RTS code for selector-thunk info tables,
1199 in which case this line will spring back to life.
1201 LFThunk _ _ upd_flag (SelectorThunk _ _ offset) -> mkSelectorInfoTableLabel upd_flag offset
1202 -- Ditto for selectors
1205 other -> {-NO: if isStaticRep rep
1206 then mkStaticInfoTableLabel id
1207 else -} mkInfoTableLabel id
1209 mkConInfoPtr :: Id -> SMRep -> CLabel
1210 mkConInfoPtr con rep
1211 = ASSERT(isDataCon con)
1213 PhantomRep -> mkPhantomInfoTableLabel con
1214 StaticRep _ _ -> mkStaticInfoTableLabel con
1215 _ -> mkConInfoTableLabel con
1217 mkConEntryPtr :: Id -> SMRep -> CLabel
1218 mkConEntryPtr con rep
1219 = ASSERT(isDataCon con)
1221 StaticRep _ _ -> mkStaticConEntryLabel con
1222 _ -> mkConEntryLabel con
1225 closureLabelFromCI (MkClosureInfo id _ rep)
1227 = mkStaticClosureLabel id
1228 -- This case catches those pesky static closures for nullary constructors
1230 closureLabelFromCI (MkClosureInfo id _ other_rep) = mkClosureLabel id
1232 entryLabelFromCI :: ClosureInfo -> CLabel
1233 entryLabelFromCI (MkClosureInfo id lf_info rep)
1235 LFThunk _ _ upd_flag std_form_info -> thunkEntryLabel id std_form_info upd_flag
1236 LFCon con _ -> mkConEntryPtr con rep
1237 LFTuple tup _ -> mkConEntryPtr tup rep
1238 other -> mkStdEntryLabel id
1240 -- thunkEntryLabel is a local help function, not exported. It's used from both
1241 -- entryLabelFromCI and getEntryConvention.
1242 -- I don't think it needs to deal with the SelectorThunk case
1243 -- Well, it's falling over now, so I've made it deal with it. (JSM)
1245 thunkEntryLabel thunk_id (VapThunk fun_id args _) is_updatable
1246 = mkVapEntryLabel fun_id is_updatable
1247 thunkEntryLabel thunk_id _ is_updatable
1248 = mkStdEntryLabel thunk_id
1252 allocProfilingMsg :: ClosureInfo -> FAST_STRING
1254 allocProfilingMsg (MkClosureInfo _ lf_info _)
1256 LFReEntrant _ _ _ -> SLIT("ALLOC_FUN")
1257 LFCon _ _ -> SLIT("ALLOC_CON")
1258 LFTuple _ _ -> SLIT("ALLOC_CON")
1259 LFThunk _ _ _ _ -> SLIT("ALLOC_THK")
1260 LFBlackHole -> SLIT("ALLOC_BH")
1261 LFImported -> panic "ALLOC_IMP"
1264 We need a black-hole closure info to pass to @allocDynClosure@ when we
1265 want to allocate the black hole on entry to a CAF.
1268 blackHoleClosureInfo (MkClosureInfo id _ _)
1269 = MkClosureInfo id LFBlackHole BlackHoleRep
1272 The register liveness when returning from a constructor. For
1273 simplicity, we claim just [node] is live for all but PhantomRep's. In
1274 truth, this means that non-constructor info tables also claim node,
1275 but since their liveness information is never used, we don't care.
1278 dataConLiveness (MkClosureInfo con _ PhantomRep)
1279 = case (dataReturnConvAlg con) of
1280 ReturnInRegs regs -> mkLiveRegsMask regs
1281 ReturnInHeap -> panic "dataConLiveness:PhantomRep in heap???"
1283 dataConLiveness _ = mkLiveRegsMask [node]
1286 %************************************************************************
1288 \subsection[ClosureInfo-Profiling-funs]{Misc functions about for profiling info.}
1290 %************************************************************************
1292 Profiling requires three pices of information to be determined for
1293 each closure's info table --- kind, description and type.
1295 The description is stored directly in the @CClosureInfoTable@ when the
1296 info table is built.
1298 The kind is determined from the @LambdaForm@ stored in the closure
1299 info using @closureKind@.
1301 The type is determined from the type information stored with the @Id@
1302 in the closure info using @closureTypeDescr@.
1305 closureKind :: ClosureInfo -> String
1307 closureKind (MkClosureInfo _ lf _)
1309 LFReEntrant _ n _ -> if n > 0 then "FN_K" else "THK_K"
1310 LFCon _ _ -> "CON_K"
1311 LFTuple _ _ -> "CON_K"
1312 LFThunk _ _ _ _ -> "THK_K"
1313 LFBlackHole -> "THK_K" -- consider BHs as thunks for the moment... (ToDo?)
1314 LFImported -> panic "IMP_KIND"
1316 closureTypeDescr :: ClosureInfo -> String
1317 closureTypeDescr (MkClosureInfo id lf _)
1318 = if (isDataCon id) then -- DataCon has function types
1319 getOccString (dataConTyCon id) -- We want the TyCon not the ->
1321 getTyDescription (idType id)