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 ( maybeCharLikeTyCon, maybeIntLikeTyCon )
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 )
107 The ``wrapper'' data type for closure information:
112 Id -- The thing bound to this closure
113 LambdaFormInfo -- info derivable from the *source*
114 SMRep -- representation used by storage manager
117 %************************************************************************
119 \subsection[ClosureInfo-OLD-DOC]{OLD DOCUMENTATION PROBABLY SUPERCEDED BY stg-details}
121 %************************************************************************
123 We can optimise the function-entry code as follows.
126 \item If the ``function'' is not updatable, we can jump directly to its
127 entry code, rather than indirecting via the info pointer in the
128 closure. (For updatable thunks we must go via the closure, in
129 case it has been updated.)
131 \item If the former bullet applies, and the application we are
132 compiling gives the function as many arguments as it needs, we
133 can jump to its fast-entry code. (This only applies if the
134 function has one or more args, because zero-arg closures have
137 \item If the function is a top-level non-constructor or imported, there
138 is no need to make Node point to its closure. In order for
139 this to be right, we need to ensure that:
141 \item If such closures are updatable then they push their
142 static address in the update frame, not Node. Actually
143 we create a black hole and push its address.
145 \item The arg satisfaction check should load Node before jumping to
148 \item Top-level constructor closures need careful handling. If we are to
149 jump direct to the constructor code, we must load Node first, even
150 though they are top-level. But if we go to their ``own''
151 standard-entry code (which loads Node and then jumps to the
152 constructor code) we don't need to load Node.
157 {\em Top level constructors (@mkStaticConEntryInfo@)}
160 x = {y,ys} \ {} Cons {y,ys} -- Std form constructor
163 x-closure: Cons-info-table, y-closure, ys-closure
165 x-entry: Node = x-closure; jump( Cons-entry )
167 x's EntryInfo in its own module:
169 Base-label = Cons -- Not x!!
171 ClosureClass = Constructor
174 So if x is entered, Node will be set up and
175 we'll jump direct to the Cons code.
177 x's EntryInfo in another module: (which may not know that x is a constructor)
179 Base-label = x -- Is x!!
180 NodeMustPoint = False -- All imported things have False
181 ClosureClass = non-committal
184 If x is entered, we'll jump to x-entry, which will set up Node
185 before jumping to the standard Cons code
187 {\em Top level non-constructors (@mkStaticEntryInfo@)}
192 For updatable thunks, x-entry must push an allocated BH in update frame, not Node.
194 For non-zero arity, arg satis check must load Node before jumping to
197 x's EntryInfo in its own module:
200 NodeMustPoint = False
201 ClosureClass = whatever
204 {\em Inner constructors (@mkConEntryInfo@)}
207 Base-label = Cons -- Not x!!
208 NodeMustPoint = True -- If its arity were zero, it would
209 -- have been lifted to top level
210 ClosureClass = Constructor
213 {\em Inner non-constructors (@mkEntryInfo@)}
217 NodeMustPoint = True -- If no free vars, would have been
218 -- lifted to top level
219 ClosureClass = whatever
228 NodeMustPoint = False
229 ClosureClass = whatever
233 THINK: we could omit making Node point to top-level constructors
234 of arity zero; but that might interact nastily with updates.
239 The info we need to import for imported things is:
242 data ImportInfo = UnknownImportInfo
243 | HnfImport Int -- Not updatable, arity given
244 -- Arity can be zero, for (eg) constrs
245 | UpdatableImport -- Must enter via the closure
248 ToDo: move this stuff???
251 mkStaticEntryInfo lbl cl_class
252 = MkEntryInfo lbl False cl_class
254 mkStaticConEntryInfo lbl
255 = MkEntryInfo lbl True ConstructorClosure
257 mkEntryInfo lbl cl_class
258 = MkEntryInfo lbl True cl_class
261 = MkEntryInfo lbl True ConstructorClosure
264 %************************************************************************
266 \subsection[ClosureInfo-datatypes]{Data types for closure information}
268 %************************************************************************
270 %************************************************************************
272 \subsubsection[LambdaFormInfo-datatype]{@LambdaFormInfo@: source-derivable info}
274 %************************************************************************
278 = LFReEntrant -- Reentrant closure; used for PAPs too
279 Bool -- True if top level
281 Bool -- True <=> no fvs
283 | LFCon -- Constructor
284 DataCon -- The constructor (may be specialised)
285 Bool -- True <=> zero arity
288 DataCon -- The tuple constructor (may be specialised)
289 Bool -- True <=> zero arity
291 | LFThunk -- Thunk (zero arity)
292 Bool -- True <=> top level
293 Bool -- True <=> no free vars
294 Bool -- True <=> updatable (i.e., *not* single-entry)
297 | LFArgument -- Used for function arguments. We know nothing about
298 -- this closure. Treat like updatable "LFThunk"...
300 | LFImported -- Used for imported things. We know nothing about this
301 -- closure. Treat like updatable "LFThunk"...
302 -- Imported things which we do know something about use
303 -- one of the other LF constructors (eg LFReEntrant for
306 | LFLetNoEscape -- See LetNoEscape module for precise description of
309 StgLiveVars-- list of variables live in the RHS of the let.
310 -- (ToDo: maybe not used)
312 | LFBlackHole -- Used for the closures allocated to hold the result
313 -- of a CAF. We want the target of the update frame to
314 -- be in the heap, so we make a black hole to hold it.
316 -- This last one is really only for completeness;
317 -- it isn't actually used for anything interesting
318 {- | LFIndirection -}
320 data StandardFormInfo -- Tells whether this thunk has one of a small number
323 = NonStandardThunk -- No, it isn't
327 DataCon -- Constructor
328 Int -- 0-origin offset of ak within the "goods" of constructor
329 -- (Recall that the a1,...,an may be laid out in the heap
330 -- in a non-obvious order.)
332 {- A SelectorThunk is of form
337 and the constructor is from a single-constr type.
338 If we can't convert the heap-offset of the selectee into an Int, e.g.,
339 it's "GEN_VHS+i", we just give up.
345 Bool -- True <=> the function is not top-level, so
346 -- must be stored in the thunk too
348 {- A VapThunk is of form
352 where f is a known function, with arity n
353 So for this thunk we can use the label for f's heap-entry
354 info table (generated when f's defn was dealt with),
355 rather than generating a one-off info table and entry code
360 mkLFArgument = LFArgument
361 mkLFBlackHole = LFBlackHole
362 mkLFLetNoEscape = LFLetNoEscape
364 mkLFImported :: Id -> LambdaFormInfo
366 = case getIdArity id of
367 ArityExactly 0 -> LFThunk True{-top-lev-} True{-no fvs-}
368 True{-updatable-} NonStandardThunk
369 ArityExactly n -> LFReEntrant True n True -- n > 0
370 other -> LFImported -- Not sure of exact arity
373 %************************************************************************
375 \subsection[ClosureInfo-construction]{Functions which build LFInfos}
377 %************************************************************************
379 @mkClosureLFInfo@ figures out the appropriate LFInfo for the closure.
382 mkClosureLFInfo :: Bool -- True of top level
384 -> UpdateFlag -- Update flag
388 mkClosureLFInfo top fvs upd_flag args@(_:_) -- Non-empty args
389 = LFReEntrant top (length args) (null fvs)
391 mkClosureLFInfo top fvs ReEntrant []
392 = LFReEntrant top 0 (null fvs)
394 mkClosureLFInfo top fvs upd_flag []
395 = LFThunk top (null fvs) (isUpdatable upd_flag) NonStandardThunk
397 isUpdatable ReEntrant = False
398 isUpdatable SingleEntry = False
399 isUpdatable Updatable = True
402 @mkConLFInfo@ is similar, for constructors.
405 mkConLFInfo :: DataCon -> LambdaFormInfo
408 = -- the isNullaryDataCon will do this: ASSERT(isDataCon con)
409 (if isTupleCon con then LFTuple else LFCon) con (isNullaryDataCon con)
411 mkSelectorLFInfo scrutinee con offset
412 = LFThunk False False True (SelectorThunk scrutinee con offset)
414 mkVapLFInfo fvs upd_flag fun_id args fun_in_vap
415 = LFThunk False (null fvs) (isUpdatable upd_flag) (VapThunk fun_id args fun_in_vap)
419 %************************************************************************
421 \subsection[ClosureInfo-sizes]{Functions about closure {\em sizes}}
423 %************************************************************************
426 closureSize :: ClosureInfo -> HeapOffset
427 closureSize cl_info@(MkClosureInfo _ _ sm_rep)
428 = totHdrSize sm_rep `addOff` (intOff (closureNonHdrSize cl_info))
430 closureSizeWithoutFixedHdr :: ClosureInfo -> HeapOffset
431 closureSizeWithoutFixedHdr cl_info@(MkClosureInfo _ _ sm_rep)
432 = varHdrSize sm_rep `addOff` (intOff (closureNonHdrSize cl_info))
434 closureHdrSize :: ClosureInfo -> HeapOffset
435 closureHdrSize (MkClosureInfo _ _ sm_rep)
438 closureNonHdrSize :: ClosureInfo -> Int
439 closureNonHdrSize cl_info@(MkClosureInfo _ lf_info sm_rep)
440 = tot_wds + computeSlopSize tot_wds sm_rep (closureUpdReqd cl_info) --ToDo: pass lf_info?
442 tot_wds = closureGoodStuffSize cl_info
444 closureGoodStuffSize :: ClosureInfo -> Int
445 closureGoodStuffSize (MkClosureInfo _ _ sm_rep)
446 = let (ptrs, nonptrs) = sizes_from_SMRep sm_rep
449 closurePtrsSize :: ClosureInfo -> Int
450 closurePtrsSize (MkClosureInfo _ _ sm_rep)
451 = let (ptrs, _) = sizes_from_SMRep sm_rep
455 sizes_from_SMRep (SpecialisedRep k ptrs nonptrs _) = (ptrs, nonptrs)
456 sizes_from_SMRep (GenericRep ptrs nonptrs _) = (ptrs, nonptrs)
457 sizes_from_SMRep (BigTupleRep ptrs) = (ptrs, 0)
458 sizes_from_SMRep (MuTupleRep ptrs) = (ptrs, 0)
459 sizes_from_SMRep (DataRep nonptrs) = (0, nonptrs)
460 sizes_from_SMRep BlackHoleRep = (0, 0)
461 sizes_from_SMRep (StaticRep ptrs nonptrs) = (ptrs, nonptrs)
463 sizes_from_SMRep PhantomRep = panic "sizes_from_SMRep: PhantomRep"
464 sizes_from_SMRep DynamicRep = panic "sizes_from_SMRep: DynamicRep"
469 fitsMinUpdSize :: ClosureInfo -> Bool
470 fitsMinUpdSize (MkClosureInfo _ _ BlackHoleRep) = True
471 fitsMinUpdSize cl_info = isSpecRep (closureSMRep cl_info) && closureNonHdrSize cl_info <= mIN_UPD_SIZE
474 Computing slop size. WARNING: this looks dodgy --- it has deep
475 knowledge of what the storage manager does with the various
481 Updateable closures must be @mIN_UPD_SIZE@.
484 Cons cell requires 2 words
486 Indirections require 1 word
488 Appels collector indirections 2 words
490 THEREFORE: @mIN_UPD_SIZE = 2@.
493 Collectable closures which are allocated in the heap
494 must be @mIN_SIZE_NonUpdHeapObject@.
496 Copying collector forward pointer requires 1 word
498 THEREFORE: @mIN_SIZE_NonUpdHeapObject = 1@
501 @SpecialisedRep@ closures closures may require slop:
504 @ConstantRep@ and @CharLikeRep@ closures always use the address of
505 a static closure. They are never allocated or
506 collected (eg hold forwarding pointer) hence never any slop.
509 @IntLikeRep@ are never updatable.
510 May need slop to be collected (as they will be size 1 or more
511 this probably has no affect)
514 @SpecRep@ may be updateable and will be collectable
517 @StaticRep@ may require slop if updatable. Non-updatable ones are OK.
520 @GenericRep@ closures will always be larger so never require slop.
523 ***** ToDo: keep an eye on this!
527 slopSize cl_info@(MkClosureInfo _ lf_info sm_rep)
528 = computeSlopSize (closureGoodStuffSize cl_info) sm_rep (closureUpdReqd cl_info)
530 computeSlopSize :: Int -> SMRep -> Bool -> Int
532 computeSlopSize tot_wds (SpecialisedRep ConstantRep _ _ _) _
534 computeSlopSize tot_wds (SpecialisedRep CharLikeRep _ _ _) _
537 computeSlopSize tot_wds (SpecialisedRep _ _ _ _) True -- Updatable
538 = max 0 (mIN_UPD_SIZE - tot_wds)
539 computeSlopSize tot_wds (StaticRep _ _) True -- Updatable
540 = max 0 (mIN_UPD_SIZE - tot_wds)
541 computeSlopSize tot_wds BlackHoleRep _ -- Updatable
542 = max 0 (mIN_UPD_SIZE - tot_wds)
544 computeSlopSize tot_wds (SpecialisedRep _ _ _ _) False -- Not updatable
545 = max 0 (mIN_SIZE_NonUpdHeapObject - tot_wds)
547 computeSlopSize tot_wds other_rep _ -- Any other rep
551 %************************************************************************
553 \subsection[layOutDynClosure]{Lay out a dynamic closure}
555 %************************************************************************
558 layOutDynClosure, layOutStaticClosure
559 :: Id -- STG identifier w/ which this closure assoc'd
560 -> (a -> PrimRep) -- function w/ which to be able to get a PrimRep
561 -> [a] -- the "things" being layed out
562 -> LambdaFormInfo -- what sort of closure it is
563 -> (ClosureInfo, -- info about the closure
564 [(a, VirtualHeapOffset)]) -- things w/ offsets pinned on them
566 layOutDynClosure name kind_fn things lf_info
567 = (MkClosureInfo name lf_info sm_rep,
570 (tot_wds, -- #ptr_wds + #nonptr_wds
572 things_w_offsets) = mkVirtHeapOffsets sm_rep kind_fn things
573 sm_rep = chooseDynSMRep lf_info tot_wds ptr_wds
575 layOutStaticClosure name kind_fn things lf_info
576 = (MkClosureInfo name lf_info (StaticRep ptr_wds (tot_wds - ptr_wds)),
579 (tot_wds, -- #ptr_wds + #nonptr_wds
581 things_w_offsets) = mkVirtHeapOffsets (StaticRep bot bot) kind_fn things
582 bot = panic "layoutStaticClosure"
584 layOutStaticNoFVClosure :: Id -> LambdaFormInfo -> ClosureInfo
585 layOutStaticNoFVClosure name lf_info
586 = MkClosureInfo name lf_info (StaticRep ptr_wds nonptr_wds)
588 -- I am very uncertain that this is right - it will show up when testing
589 -- my dynamic loading code. ADR
590 -- (If it's not right, we'll have to grab the kinds of the arguments from
595 layOutPhantomClosure :: Id -> LambdaFormInfo -> ClosureInfo
596 layOutPhantomClosure name lf_info = MkClosureInfo name lf_info PhantomRep
599 A wrapper for when used with data constructors:
601 layOutDynCon :: DataCon
604 -> (ClosureInfo, [(a,VirtualHeapOffset)])
606 layOutDynCon con kind_fn args
607 = ASSERT(isDataCon con)
608 layOutDynClosure con kind_fn args (mkConLFInfo con)
612 %************************************************************************
614 \subsection[SMreps]{Choosing SM reps}
616 %************************************************************************
621 -> Int -> Int -- Tot wds, ptr wds
624 chooseDynSMRep lf_info tot_wds ptr_wds
626 nonptr_wds = tot_wds - ptr_wds
628 updatekind = case lf_info of
629 LFThunk _ _ upd _ -> if upd then SMUpdatable else SMSingleEntry
630 LFBlackHole -> SMUpdatable
633 if (nonptr_wds == 0 && ptr_wds <= mAX_SPEC_ALL_PTRS)
634 || (tot_wds <= mAX_SPEC_MIXED_FIELDS)
635 || (ptr_wds == 0 && nonptr_wds <= mAX_SPEC_ALL_NONPTRS) then
637 spec_kind = case lf_info of
639 (LFTuple _ True) -> ConstantRep
641 (LFTuple _ _) -> SpecRep
643 (LFCon _ True) -> ConstantRep
645 (LFCon con _ ) -> if maybeToBool (maybeCharLikeTyCon tycon) then CharLikeRep
646 else if maybeToBool (maybeIntLikeTyCon tycon) then IntLikeRep
649 tycon = dataConTyCon con
653 SpecialisedRep spec_kind ptr_wds nonptr_wds updatekind
655 GenericRep ptr_wds nonptr_wds updatekind
659 %************************************************************************
661 \subsection[mkVirtHeapOffsets]{Assigning heap offsets in a closure}
663 %************************************************************************
665 @mkVirtHeapOffsets@ (the heap version) always returns boxed things with
666 smaller offsets than the unboxed things, and furthermore, the offsets in
670 mkVirtHeapOffsets :: SMRep -- Representation to be used by storage manager
671 -> (a -> PrimRep) -- To be able to grab kinds;
672 -- w/ a kind, we can find boxedness
673 -> [a] -- Things to make offsets for
674 -> (Int, -- *Total* number of words allocated
675 Int, -- Number of words allocated for *pointers*
676 [(a, VirtualHeapOffset)])
677 -- Things with their offsets from start of object
678 -- in order of increasing offset
680 -- First in list gets lowest offset, which is initial offset + 1.
682 mkVirtHeapOffsets sm_rep kind_fun things
683 = let (ptrs, non_ptrs) = separateByPtrFollowness kind_fun things
684 (wds_of_ptrs, ptrs_w_offsets) = mapAccumL computeOffset 0 ptrs
685 (tot_wds, non_ptrs_w_offsets) = mapAccumL computeOffset wds_of_ptrs non_ptrs
687 (tot_wds, wds_of_ptrs, ptrs_w_offsets ++ non_ptrs_w_offsets)
689 offset_of_first_word = totHdrSize sm_rep
690 computeOffset wds_so_far thing
691 = (wds_so_far + (getPrimRepSize . kind_fun) thing,
692 (thing, (offset_of_first_word `addOff` (intOff wds_so_far)))
696 %************************************************************************
698 \subsection[ClosureInfo-4-questions]{Four major questions about @ClosureInfo@}
700 %************************************************************************
702 Be sure to see the stg-details notes about these...
705 nodeMustPointToIt :: LambdaFormInfo -> FCode Bool
706 nodeMustPointToIt lf_info
708 do_profiling = opt_SccProfilingOn
711 LFReEntrant top arity no_fvs -> returnFC (
712 not no_fvs || -- Certainly if it has fvs we need to point to it
714 not top -- If it is not top level we will point to it
715 -- We can have a \r closure with no_fvs which
716 -- is not top level as special case cgRhsClosure
717 -- has been dissabled in favour of let floating
719 -- For lex_profiling we also access the cost centre for a
720 -- non-inherited function i.e. not top level
721 -- the not top case above ensures this is ok.
724 LFCon _ zero_arity -> returnFC True
725 LFTuple _ zero_arity -> returnFC True
727 -- Strictly speaking, the above two don't need Node to point
728 -- to it if the arity = 0. But this is a *really* unlikely
729 -- situation. If we know it's nil (say) and we are entering
730 -- it. Eg: let x = [] in x then we will certainly have inlined
731 -- x, since nil is a simple atom. So we gain little by not
732 -- having Node point to known zero-arity things. On the other
733 -- hand, we do lose something; Patrick's code for figuring out
734 -- when something has been updated but not entered relies on
735 -- having Node point to the result of an update. SLPJ
738 LFThunk _ no_fvs updatable NonStandardThunk
739 -> returnFC (updatable || not no_fvs || do_profiling)
741 -- For the non-updatable (single-entry case):
743 -- True if has fvs (in which case we need access to them, and we
744 -- should black-hole it)
745 -- or profiling (in which case we need to recover the cost centre
748 LFThunk _ no_fvs updatable some_standard_form_thunk
750 -- Node must point to any standard-form thunk.
753 -- generates a Vap thunk for (f y), and even if y is a global
754 -- variable we must still make Node point to the thunk before entering it
755 -- because that's what the standard-form code expects.
757 LFArgument -> returnFC True
758 LFImported -> returnFC True
759 LFBlackHole -> returnFC True
760 -- BH entry may require Node to point
762 LFLetNoEscape _ _ -> returnFC False
765 The entry conventions depend on the type of closure being entered,
766 whether or not it has free variables, and whether we're running
767 sequentially or in parallel.
769 \begin{tabular}{lllll}
770 Closure Characteristics & Parallel & Node Req'd & Argument Passing & Enter Via \\
771 Unknown & no & yes & stack & node \\
772 Known fun ($\ge$ 1 arg), no fvs & no & no & registers & fast entry (enough args) \\
773 \ & \ & \ & \ & slow entry (otherwise) \\
774 Known fun ($\ge$ 1 arg), fvs & no & yes & registers & fast entry (enough args) \\
775 0 arg, no fvs @\r,\s@ & no & no & n/a & direct entry \\
776 0 arg, no fvs @\u@ & no & yes & n/a & node \\
777 0 arg, fvs @\r,\s@ & no & yes & n/a & direct entry \\
778 0 arg, fvs @\u@ & no & yes & n/a & node \\
780 Unknown & yes & yes & stack & node \\
781 Known fun ($\ge$ 1 arg), no fvs & yes & no & registers & fast entry (enough args) \\
782 \ & \ & \ & \ & slow entry (otherwise) \\
783 Known fun ($\ge$ 1 arg), fvs & yes & yes & registers & node \\
784 0 arg, no fvs @\r,\s@ & yes & no & n/a & direct entry \\
785 0 arg, no fvs @\u@ & yes & yes & n/a & node \\
786 0 arg, fvs @\r,\s@ & yes & yes & n/a & node \\
787 0 arg, fvs @\u@ & yes & yes & n/a & node\\
790 When black-holing, single-entry closures could also be entered via node
791 (rather than directly) to catch double-entry.
795 = ViaNode -- The "normal" convention
797 | StdEntry CLabel -- Jump to this code, with args on stack
798 (Maybe CLabel) -- possibly setting infoptr to this
800 | DirectEntry -- Jump directly to code, with args in regs
801 CLabel -- The code label
803 [MagicId] -- Its register assignments (possibly empty)
805 getEntryConvention :: Id -- Function being applied
806 -> LambdaFormInfo -- Its info
807 -> [PrimRep] -- Available arguments
808 -> FCode EntryConvention
810 getEntryConvention id lf_info arg_kinds
811 = nodeMustPointToIt lf_info `thenFC` \ node_points ->
813 is_concurrent = opt_ForConcurrent
817 if (node_points && is_concurrent) then ViaNode else
821 LFReEntrant _ arity _ ->
822 if arity == 0 || (length arg_kinds) < arity then
823 StdEntry (mkStdEntryLabel id) Nothing
825 DirectEntry (mkFastEntryLabel id arity) arity arg_regs
827 (arg_regs, _) = assignRegs live_regs (take arity arg_kinds)
828 live_regs = if node_points then [node] else []
831 -> let itbl = if zero_arity then
832 mkPhantomInfoTableLabel con
834 mkConInfoTableLabel con
836 --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
837 StdEntry (mkConEntryLabel con) (Just itbl)
839 LFTuple tup zero_arity
840 -> --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
841 StdEntry (mkConEntryLabel tup) (Just (mkConInfoTableLabel tup))
843 LFThunk _ _ updatable std_form_info
846 else StdEntry (thunkEntryLabel id std_form_info updatable) Nothing
848 LFArgument -> ViaNode
849 LFImported -> ViaNode
850 LFBlackHole -> ViaNode -- Presumably the black hole has by now
851 -- been updated, but we don't know with
852 -- what, so we enter via Node
854 LFLetNoEscape arity _
855 -> ASSERT(arity == length arg_kinds)
856 DirectEntry (mkStdEntryLabel id) arity arg_regs
858 (arg_regs, _) = assignRegs live_regs arg_kinds
859 live_regs = if node_points then [node] else []
862 blackHoleOnEntry :: Bool -- No-black-holing flag
866 -- Static closures are never themselves black-holed.
867 -- Updatable ones will be overwritten with a CAFList cell, which points to a black hole;
868 -- Single-entry ones have no fvs to plug, and we trust they don't form part of a loop.
870 blackHoleOnEntry no_black_holing (MkClosureInfo _ _ (StaticRep _ _)) = False
872 blackHoleOnEntry no_black_holing (MkClosureInfo _ lf_info _)
874 LFReEntrant _ _ _ -> False
875 LFThunk _ no_fvs updatable _
877 then not no_black_holing
879 other -> panic "blackHoleOnEntry" -- Should never happen
881 getStandardFormThunkInfo
883 -> Maybe [StgArg] -- Nothing => not a standard-form thunk
884 -- Just atoms => a standard-form thunk with payload atoms
886 getStandardFormThunkInfo (LFThunk _ _ _ (SelectorThunk scrutinee _ _))
887 = --trace "Selector thunk: missed opportunity to save info table + code"
889 -- Just [StgVarArg scrutinee]
890 -- We can't save the info tbl + code until we have a way to generate
891 -- a fixed family thereof.
893 getStandardFormThunkInfo (LFThunk _ _ _ (VapThunk fun_id args fun_in_payload))
894 | fun_in_payload = Just (StgVarArg fun_id : args)
895 | otherwise = Just args
897 getStandardFormThunkInfo other_lf_info = Nothing
899 maybeSelectorInfo (MkClosureInfo _ (LFThunk _ _ _ (SelectorThunk _ con offset)) _) = Just (con,offset)
900 maybeSelectorInfo _ = Nothing
903 Avoiding generating entries and info tables
904 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
905 At present, for every function we generate all of the following,
906 just in case. But they aren't always all needed, as noted below:
908 [NB1: all of this applies only to *functions*. Thunks always
909 have closure, info table, and entry code.]
911 [NB2: All are needed if the function is *exported*, just to play safe.]
914 * Fast-entry code ALWAYS NEEDED
917 Needed iff (a) we have any un-saturated calls to the function
918 OR (b) the function is passed as an arg
919 OR (c) we're in the parallel world and the function has free vars
920 [Reason: in parallel world, we always enter functions
921 with free vars via the closure.]
923 * The function closure
924 Needed iff (a) we have any un-saturated calls to the function
925 OR (b) the function is passed as an arg
926 OR (c) if the function has free vars (ie not top level)
928 Why case (a) here? Because if the arg-satis check fails,
929 UpdatePAP stuffs a pointer to the function closure in the PAP.
930 [Could be changed; UpdatePAP could stuff in a code ptr instead,
931 but doesn't seem worth it.]
933 [NB: these conditions imply that we might need the closure
934 without the slow-entry code. Here's how.
936 f x y = let g w = ...x..y..w...
940 Here we need a closure for g which contains x and y,
941 but since the calls are all saturated we just jump to the
942 fast entry point for g, with R1 pointing to the closure for g.]
945 * Standard info table
946 Needed iff (a) we have any un-saturated calls to the function
947 OR (b) the function is passed as an arg
948 OR (c) the function has free vars (ie not top level)
950 NB. In the sequential world, (c) is only required so that the function closure has
951 an info table to point to, to keep the storage manager happy.
952 If (c) alone is true we could fake up an info table by choosing
953 one of a standard family of info tables, whose entry code just
956 [NB In the parallel world (c) is needed regardless because
957 we enter functions with free vars via the closure.]
959 If (c) is retained, then we'll sometimes generate an info table
960 (for storage mgr purposes) without slow-entry code. Then we need
961 to use an error label in the info table to substitute for the absent
964 * Standard vap-entry code
965 Standard vap-entry info table
966 Needed iff we have any updatable thunks of the standard vap-entry shape.
968 * Single-update vap-entry code
969 Single-update vap-entry info table
970 Needed iff we have any non-updatable thunks of the
971 standard vap-entry shape.
975 staticClosureRequired
980 staticClosureRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
981 (LFReEntrant top_level _ _) -- It's a function
982 = ASSERT( top_level ) -- Assumption: it's a top-level, no-free-var binding
983 arg_occ -- There's an argument occurrence
984 || unsat_occ -- There's an unsaturated call
985 || externallyVisibleId binder
987 staticClosureRequired binder other_binder_info other_lf_info = True
989 slowFunEntryCodeRequired -- Assumption: it's a function, not a thunk.
994 slowFunEntryCodeRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _) entry_conv
995 = arg_occ -- There's an argument occurrence
996 || unsat_occ -- There's an unsaturated call
997 || externallyVisibleId binder
998 || (case entry_conv of { DirectEntry _ _ _ -> False; other -> True })
999 {- The last case deals with the parallel world; a function usually
1000 as a DirectEntry convention, but if it doesn't we must generate slow-entry code -}
1002 slowFunEntryCodeRequired binder NoStgBinderInfo _ = True
1004 funInfoTableRequired
1009 funInfoTableRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
1010 (LFReEntrant top_level _ _)
1012 || arg_occ -- There's an argument occurrence
1013 || unsat_occ -- There's an unsaturated call
1014 || externallyVisibleId binder
1016 funInfoTableRequired other_binder_info binder other_lf_info = True
1018 -- We need the vector-apply entry points for a function if
1019 -- there's a vector-apply occurrence in this module
1021 stdVapRequired, noUpdVapRequired :: StgBinderInfo -> Bool
1023 stdVapRequired binder_info
1024 = case binder_info of
1025 StgBinderInfo _ _ std_vap_occ _ _ -> std_vap_occ
1028 noUpdVapRequired binder_info
1029 = case binder_info of
1030 StgBinderInfo _ _ _ no_upd_vap_occ _ -> no_upd_vap_occ
1034 @lfArity@ extracts the arity of a function from its LFInfo
1037 {- Not needed any more
1039 lfArity_maybe (LFReEntrant _ arity _) = Just arity
1041 -- Removed SLPJ March 97. I don't believe these two;
1042 -- LFCon is used for construcor *applications*, not constructors!
1044 -- lfArity_maybe (LFCon con _) = Just (dataConArity con)
1045 -- lfArity_maybe (LFTuple con _) = Just (dataConArity con)
1047 lfArity_maybe other = Nothing
1051 %************************************************************************
1053 \subsection[ClosureInfo-misc-funs]{Misc functions about @ClosureInfo@, etc.}
1055 %************************************************************************
1059 isStaticClosure :: ClosureInfo -> Bool
1060 isStaticClosure (MkClosureInfo _ _ rep) = isStaticRep rep
1062 closureId :: ClosureInfo -> Id
1063 closureId (MkClosureInfo id _ _) = id
1065 closureSMRep :: ClosureInfo -> SMRep
1066 closureSMRep (MkClosureInfo _ _ sm_rep) = sm_rep
1068 closureLFInfo :: ClosureInfo -> LambdaFormInfo
1069 closureLFInfo (MkClosureInfo _ lf_info _) = lf_info
1071 closureUpdReqd :: ClosureInfo -> Bool
1073 closureUpdReqd (MkClosureInfo _ (LFThunk _ _ upd _) _) = upd
1074 closureUpdReqd (MkClosureInfo _ LFBlackHole _) = True
1075 -- Black-hole closures are allocated to receive the results of an
1076 -- alg case with a named default... so they need to be updated.
1077 closureUpdReqd other_closure = False
1079 closureSingleEntry :: ClosureInfo -> Bool
1081 closureSingleEntry (MkClosureInfo _ (LFThunk _ _ upd _) _) = not upd
1082 closureSingleEntry other_closure = False
1085 Note: @closureType@ returns appropriately specialised tycon and
1088 closureType :: ClosureInfo -> Maybe (TyCon, [Type], [Id])
1090 -- First, a turgid special case. When we are generating the
1091 -- standard code and info-table for Vaps (which is done when the function
1092 -- defn is encountered), we don't have a convenient Id to hand whose
1093 -- type is that of (f x y z). So we need to figure out the type
1094 -- rather than take it from the Id. The Id is probably just "f"!
1096 closureType (MkClosureInfo id (LFThunk _ _ _ (VapThunk fun_id args _)) _)
1097 = splitAlgTyConApp_maybe (fun_result_ty (length args) (idType fun_id))
1099 closureType (MkClosureInfo id lf _) = splitAlgTyConApp_maybe (idType id)
1102 @closureReturnsUnpointedType@ is used to check whether a closure, {\em
1103 once it has eaten its arguments}, returns an unboxed type. For
1104 example, the closure for a function:
1108 returns an unboxed type. This is important when dealing with stack
1111 closureReturnsUnpointedType :: ClosureInfo -> Bool
1113 closureReturnsUnpointedType (MkClosureInfo fun_id (LFReEntrant _ arity _) _)
1114 = isUnpointedType (fun_result_ty arity (idType fun_id))
1116 closureReturnsUnpointedType other_closure = False
1117 -- All non-function closures aren't functions,
1118 -- and hence are boxed, since they are heap alloc'd
1120 -- fun_result_ty is a disgusting little bit of code that finds the result
1121 -- type of a function application. It looks "through" new types.
1122 -- We don't have type args available any more, so we are pretty cavilier,
1123 -- and quite possibly plain wrong. Let's hope it doesn't matter if we are!
1125 fun_result_ty arity ty
1126 | arity <= n_arg_tys
1127 = mkFunTys (drop arity arg_tys) res_ty
1130 = case splitAlgTyConApp_maybe res_ty of
1131 Nothing -> pprPanic "fun_result_ty:" (hsep [int arity,
1134 Just (tycon, tycon_arg_tys, [con]) | isNewTyCon tycon
1135 -> fun_result_ty (arity - n_arg_tys) rep_ty
1137 ([rep_ty], _) = splitFunTys (applyTys (idType con) tycon_arg_tys)
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)