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 IMPORT_DELOOPER(AbsCLoop) -- here for paranoia-checking
61 import Constants ( mIN_UPD_SIZE, mIN_SIZE_NonUpdHeapObject,
62 mAX_SPEC_ALL_PTRS, mAX_SPEC_MIXED_FIELDS,
66 import CgRetConv ( assignRegs, dataReturnConvAlg,
67 DataReturnConvention(..)
69 import CLabel ( mkStdEntryLabel, mkFastEntryLabel,
70 mkPhantomInfoTableLabel, mkInfoTableLabel,
71 mkConInfoTableLabel, mkStaticClosureLabel,
72 mkBlackHoleInfoTableLabel, mkVapInfoTableLabel,
73 mkStaticInfoTableLabel, mkStaticConEntryLabel,
74 mkConEntryLabel, mkClosureLabel, mkVapEntryLabel
76 import CmdLineOpts ( opt_SccProfilingOn, opt_ForConcurrent )
77 import HeapOffs ( intOff, addOff, totHdrSize, varHdrSize,
78 SYN_IE(VirtualHeapOffset), HeapOffset
80 import Id ( idType, getIdArity,
82 dataConTag, fIRST_TAG,
83 isDataCon, isNullaryDataCon, dataConTyCon,
84 isTupleCon, SYN_IE(DataCon),
85 GenId{-instance Eq-}, SYN_IE(Id)
87 import IdInfo ( ArityInfo(..) )
88 import Maybes ( maybeToBool )
89 import Name ( getOccString )
90 import PprStyle ( PprStyle(..) )
91 import PprType ( getTyDescription, GenType{-instance Outputable-} )
92 import Pretty --ToDo:rm
93 import PrelInfo ( maybeCharLikeTyCon, maybeIntLikeTyCon )
94 import PrimRep ( getPrimRepSize, separateByPtrFollowness, PrimRep )
95 import SMRep -- all of it
96 import TyCon ( TyCon{-instance NamedThing-} )
97 import Type ( isPrimType, splitForAllTy, splitFunTyExpandingDictsAndPeeking,
98 mkFunTys, maybeAppSpecDataTyConExpandingDicts,
101 import Util ( isIn, mapAccumL, panic, pprPanic, assertPanic )
102 #if __GLASGOW_HASKELL__ >= 202
103 import Outputable ( Outputable(..) )
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 _
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 LFArgument -> returnFC True
749 LFImported -> returnFC True
750 LFBlackHole -> returnFC True
751 -- BH entry may require Node to point
753 LFLetNoEscape _ _ -> returnFC False
756 The entry conventions depend on the type of closure being entered,
757 whether or not it has free variables, and whether we're running
758 sequentially or in parallel.
760 \begin{tabular}{lllll}
761 Closure Characteristics & Parallel & Node Req'd & Argument Passing & Enter Via \\
762 Unknown & no & yes & stack & node \\
763 Known fun ($\ge$ 1 arg), no fvs & no & no & registers & fast entry (enough args) \\
764 \ & \ & \ & \ & slow entry (otherwise) \\
765 Known fun ($\ge$ 1 arg), fvs & no & yes & registers & fast entry (enough args) \\
766 0 arg, no fvs @\r,\s@ & no & no & n/a & direct entry \\
767 0 arg, no fvs @\u@ & no & yes & n/a & node \\
768 0 arg, fvs @\r,\s@ & no & yes & n/a & direct entry \\
769 0 arg, fvs @\u@ & no & yes & n/a & node \\
771 Unknown & yes & yes & stack & node \\
772 Known fun ($\ge$ 1 arg), no fvs & yes & no & registers & fast entry (enough args) \\
773 \ & \ & \ & \ & slow entry (otherwise) \\
774 Known fun ($\ge$ 1 arg), fvs & yes & yes & registers & node \\
775 0 arg, no fvs @\r,\s@ & yes & no & n/a & direct entry \\
776 0 arg, no fvs @\u@ & yes & yes & n/a & node \\
777 0 arg, fvs @\r,\s@ & yes & yes & n/a & node \\
778 0 arg, fvs @\u@ & yes & yes & n/a & node\\
781 When black-holing, single-entry closures could also be entered via node
782 (rather than directly) to catch double-entry.
786 = ViaNode -- The "normal" convention
788 | StdEntry CLabel -- Jump to this code, with args on stack
789 (Maybe CLabel) -- possibly setting infoptr to this
791 | DirectEntry -- Jump directly to code, with args in regs
792 CLabel -- The code label
794 [MagicId] -- Its register assignments (possibly empty)
796 getEntryConvention :: Id -- Function being applied
797 -> LambdaFormInfo -- Its info
798 -> [PrimRep] -- Available arguments
799 -> FCode EntryConvention
801 getEntryConvention id lf_info arg_kinds
802 = nodeMustPointToIt lf_info `thenFC` \ node_points ->
804 is_concurrent = opt_ForConcurrent
808 if (node_points && is_concurrent) then ViaNode else
812 LFReEntrant _ arity _ ->
813 if arity == 0 || (length arg_kinds) < arity then
814 StdEntry (mkStdEntryLabel id) Nothing
816 DirectEntry (mkFastEntryLabel id arity) arity arg_regs
818 (arg_regs, _) = assignRegs live_regs (take arity arg_kinds)
819 live_regs = if node_points then [node] else []
822 -> let itbl = if zero_arity then
823 mkPhantomInfoTableLabel con
825 mkConInfoTableLabel con
827 --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
828 StdEntry (mkConEntryLabel con) (Just itbl)
830 LFTuple tup zero_arity
831 -> --false:ASSERT (null arg_kinds) -- Should have no args (meaning what?)
832 StdEntry (mkConEntryLabel tup) (Just (mkConInfoTableLabel tup))
834 LFThunk _ _ updatable std_form_info
837 else StdEntry (thunkEntryLabel id std_form_info updatable) Nothing
839 LFArgument -> ViaNode
840 LFImported -> ViaNode
841 LFBlackHole -> ViaNode -- Presumably the black hole has by now
842 -- been updated, but we don't know with
843 -- what, so we enter via Node
845 LFLetNoEscape arity _
846 -> ASSERT(arity == length arg_kinds)
847 DirectEntry (mkStdEntryLabel id) arity arg_regs
849 (arg_regs, _) = assignRegs live_regs arg_kinds
850 live_regs = if node_points then [node] else []
853 blackHoleOnEntry :: Bool -- No-black-holing flag
857 -- Static closures are never themselves black-holed.
858 -- Updatable ones will be overwritten with a CAFList cell, which points to a black hole;
859 -- Single-entry ones have no fvs to plug, and we trust they don't form part of a loop.
861 blackHoleOnEntry no_black_holing (MkClosureInfo _ _ (StaticRep _ _)) = False
863 blackHoleOnEntry no_black_holing (MkClosureInfo _ lf_info _)
865 LFReEntrant _ _ _ -> False
866 LFThunk _ no_fvs updatable _
868 then not no_black_holing
870 other -> panic "blackHoleOnEntry" -- Should never happen
872 getStandardFormThunkInfo
874 -> Maybe [StgArg] -- Nothing => not a standard-form thunk
875 -- Just atoms => a standard-form thunk with payload atoms
877 getStandardFormThunkInfo (LFThunk _ _ _ (SelectorThunk scrutinee _ _))
878 = --trace "Selector thunk: missed opportunity to save info table + code"
880 -- Just [StgVarArg scrutinee]
881 -- We can't save the info tbl + code until we have a way to generate
882 -- a fixed family thereof.
884 getStandardFormThunkInfo (LFThunk _ _ _ (VapThunk fun_id args fun_in_payload))
885 | fun_in_payload = Just (StgVarArg fun_id : args)
886 | otherwise = Just args
888 getStandardFormThunkInfo other_lf_info = Nothing
890 maybeSelectorInfo (MkClosureInfo _ (LFThunk _ _ _ (SelectorThunk _ con offset)) _) = Just (con,offset)
891 maybeSelectorInfo _ = Nothing
894 Avoiding generating entries and info tables
895 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
896 At present, for every function we generate all of the following,
897 just in case. But they aren't always all needed, as noted below:
899 [NB1: all of this applies only to *functions*. Thunks always
900 have closure, info table, and entry code.]
902 [NB2: All are needed if the function is *exported*, just to play safe.]
905 * Fast-entry code ALWAYS NEEDED
908 Needed iff (a) we have any un-saturated calls to the function
909 OR (b) the function is passed as an arg
910 OR (c) we're in the parallel world and the function has free vars
911 [Reason: in parallel world, we always enter functions
912 with free vars via the closure.]
914 * The function closure
915 Needed iff (a) we have any un-saturated calls to the function
916 OR (b) the function is passed as an arg
917 OR (c) if the function has free vars (ie not top level)
919 Why case (a) here? Because if the arg-satis check fails,
920 UpdatePAP stuffs a pointer to the function closure in the PAP.
921 [Could be changed; UpdatePAP could stuff in a code ptr instead,
922 but doesn't seem worth it.]
924 [NB: these conditions imply that we might need the closure
925 without the slow-entry code. Here's how.
927 f x y = let g w = ...x..y..w...
931 Here we need a closure for g which contains x and y,
932 but since the calls are all saturated we just jump to the
933 fast entry point for g, with R1 pointing to the closure for g.]
936 * Standard info table
937 Needed iff (a) we have any un-saturated calls to the function
938 OR (b) the function is passed as an arg
939 OR (c) the function has free vars (ie not top level)
941 NB. In the sequential world, (c) is only required so that the function closure has
942 an info table to point to, to keep the storage manager happy.
943 If (c) alone is true we could fake up an info table by choosing
944 one of a standard family of info tables, whose entry code just
947 [NB In the parallel world (c) is needed regardless because
948 we enter functions with free vars via the closure.]
950 If (c) is retained, then we'll sometimes generate an info table
951 (for storage mgr purposes) without slow-entry code. Then we need
952 to use an error label in the info table to substitute for the absent
955 * Standard vap-entry code
956 Standard vap-entry info table
957 Needed iff we have any updatable thunks of the standard vap-entry shape.
959 * Single-update vap-entry code
960 Single-update vap-entry info table
961 Needed iff we have any non-updatable thunks of the
962 standard vap-entry shape.
966 staticClosureRequired
971 staticClosureRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
972 (LFReEntrant top_level _ _) -- It's a function
973 = ASSERT( top_level ) -- Assumption: it's a top-level, no-free-var binding
974 arg_occ -- There's an argument occurrence
975 || unsat_occ -- There's an unsaturated call
976 || externallyVisibleId binder
978 staticClosureRequired binder other_binder_info other_lf_info = True
980 slowFunEntryCodeRequired -- Assumption: it's a function, not a thunk.
984 slowFunEntryCodeRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
985 = arg_occ -- There's an argument occurrence
986 || unsat_occ -- There's an unsaturated call
987 || externallyVisibleId binder
988 {- HAS FREE VARS AND IS PARALLEL WORLD -}
990 slowFunEntryCodeRequired binder NoStgBinderInfo = True
997 funInfoTableRequired binder (StgBinderInfo arg_occ unsat_occ _ _ _)
998 (LFReEntrant top_level _ _)
1000 || arg_occ -- There's an argument occurrence
1001 || unsat_occ -- There's an unsaturated call
1002 || externallyVisibleId binder
1004 funInfoTableRequired other_binder_info binder other_lf_info = True
1006 -- We need the vector-apply entry points for a function if
1007 -- there's a vector-apply occurrence in this module
1009 stdVapRequired, noUpdVapRequired :: StgBinderInfo -> Bool
1011 stdVapRequired binder_info
1012 = case binder_info of
1013 StgBinderInfo _ _ std_vap_occ _ _ -> std_vap_occ
1016 noUpdVapRequired binder_info
1017 = case binder_info of
1018 StgBinderInfo _ _ _ no_upd_vap_occ _ -> no_upd_vap_occ
1022 @lfArity@ extracts the arity of a function from its LFInfo
1025 {- Not needed any more
1027 lfArity_maybe (LFReEntrant _ arity _) = Just arity
1029 -- Removed SLPJ March 97. I don't believe these two;
1030 -- LFCon is used for construcor *applications*, not constructors!
1032 -- lfArity_maybe (LFCon con _) = Just (dataConArity con)
1033 -- lfArity_maybe (LFTuple con _) = Just (dataConArity con)
1035 lfArity_maybe other = Nothing
1039 %************************************************************************
1041 \subsection[ClosureInfo-misc-funs]{Misc functions about @ClosureInfo@, etc.}
1043 %************************************************************************
1047 isStaticClosure :: ClosureInfo -> Bool
1048 isStaticClosure (MkClosureInfo _ _ rep) = isStaticRep rep
1050 closureId :: ClosureInfo -> Id
1051 closureId (MkClosureInfo id _ _) = id
1053 closureSMRep :: ClosureInfo -> SMRep
1054 closureSMRep (MkClosureInfo _ _ sm_rep) = sm_rep
1056 closureLFInfo :: ClosureInfo -> LambdaFormInfo
1057 closureLFInfo (MkClosureInfo _ lf_info _) = lf_info
1059 closureUpdReqd :: ClosureInfo -> Bool
1061 closureUpdReqd (MkClosureInfo _ (LFThunk _ _ upd _) _) = upd
1062 closureUpdReqd (MkClosureInfo _ LFBlackHole _) = True
1063 -- Black-hole closures are allocated to receive the results of an
1064 -- alg case with a named default... so they need to be updated.
1065 closureUpdReqd other_closure = False
1067 closureSingleEntry :: ClosureInfo -> Bool
1069 closureSingleEntry (MkClosureInfo _ (LFThunk _ _ upd _) _) = not upd
1070 closureSingleEntry other_closure = False
1073 Note: @closureType@ returns appropriately specialised tycon and
1076 closureType :: ClosureInfo -> Maybe (TyCon, [Type], [Id])
1078 -- First, a turgid special case. When we are generating the
1079 -- standard code and info-table for Vaps (which is done when the function
1080 -- defn is encountered), we don't have a convenient Id to hand whose
1081 -- type is that of (f x y z). So we need to figure out the type
1082 -- rather than take it from the Id. The Id is probably just "f"!
1084 closureType (MkClosureInfo id (LFThunk _ _ _ (VapThunk fun_id args _)) _)
1085 = maybeAppSpecDataTyConExpandingDicts (fun_result_ty (length args) fun_id)
1087 closureType (MkClosureInfo id lf _) = maybeAppSpecDataTyConExpandingDicts (idType id)
1090 @closureReturnsUnboxedType@ is used to check whether a closure, {\em
1091 once it has eaten its arguments}, returns an unboxed type. For
1092 example, the closure for a function:
1096 returns an unboxed type. This is important when dealing with stack
1099 closureReturnsUnboxedType :: ClosureInfo -> Bool
1101 closureReturnsUnboxedType (MkClosureInfo fun_id (LFReEntrant _ arity _) _)
1102 = isPrimType (fun_result_ty arity fun_id)
1104 closureReturnsUnboxedType other_closure = False
1105 -- All non-function closures aren't functions,
1106 -- and hence are boxed, since they are heap alloc'd
1108 -- ToDo: need anything like this in Type.lhs?
1109 fun_result_ty arity id
1111 (arg_tys, res_ty) = splitFunTyExpandingDictsAndPeeking (idType id)
1113 -- ASSERT(arity >= 0 && length arg_tys >= arity)
1114 (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)])) $
1115 mkFunTys (drop arity arg_tys) res_ty
1119 closureSemiTag :: ClosureInfo -> Int
1121 closureSemiTag (MkClosureInfo _ lf_info _)
1123 LFCon data_con _ -> dataConTag data_con - fIRST_TAG
1125 _ -> fromInteger oTHER_TAG
1129 isToplevClosure :: ClosureInfo -> Bool
1131 isToplevClosure (MkClosureInfo _ lf_info _)
1133 LFReEntrant top _ _ -> top
1134 LFThunk top _ _ _ -> top
1135 _ -> panic "ClosureInfo:isToplevClosure"
1141 fastLabelFromCI :: ClosureInfo -> CLabel
1142 fastLabelFromCI (MkClosureInfo id lf_info _)
1143 {- [SLPJ Changed March 97]
1144 (was ok, but is the only call to lfArity,
1145 and the id should guarantee to have the correct arity in it.
1147 = case lfArity_maybe lf_info of
1150 = case getIdArity id of
1151 ArityExactly arity -> mkFastEntryLabel id arity
1152 other -> pprPanic "fastLabelFromCI" (ppr PprDebug id)
1154 infoTableLabelFromCI :: ClosureInfo -> CLabel
1155 infoTableLabelFromCI (MkClosureInfo id lf_info rep)
1157 LFCon con _ -> mkConInfoPtr con rep
1158 LFTuple tup _ -> mkConInfoPtr tup rep
1160 LFBlackHole -> mkBlackHoleInfoTableLabel
1162 LFThunk _ _ upd_flag (VapThunk fun_id args _) -> mkVapInfoTableLabel fun_id upd_flag
1163 -- Use the standard vap info table
1164 -- for the function, rather than a one-off one
1165 -- for this particular closure
1167 {- For now, we generate individual info table and entry code for selector thunks,
1168 so their info table should be labelled in the standard way.
1169 The only special thing about them is that the info table has a field which
1170 tells the GC that it really is a selector.
1172 Later, perhaps, we'll have some standard RTS code for selector-thunk info tables,
1173 in which case this line will spring back to life.
1175 LFThunk _ _ upd_flag (SelectorThunk _ _ offset) -> mkSelectorInfoTableLabel upd_flag offset
1176 -- Ditto for selectors
1179 other -> {-NO: if isStaticRep rep
1180 then mkStaticInfoTableLabel id
1181 else -} mkInfoTableLabel id
1183 mkConInfoPtr :: Id -> SMRep -> CLabel
1184 mkConInfoPtr con rep
1185 = ASSERT(isDataCon con)
1187 PhantomRep -> mkPhantomInfoTableLabel con
1188 StaticRep _ _ -> mkStaticInfoTableLabel con
1189 _ -> mkConInfoTableLabel con
1191 mkConEntryPtr :: Id -> SMRep -> CLabel
1192 mkConEntryPtr con rep
1193 = ASSERT(isDataCon con)
1195 StaticRep _ _ -> mkStaticConEntryLabel con
1196 _ -> mkConEntryLabel con
1199 closureLabelFromCI (MkClosureInfo id _ rep)
1201 = mkStaticClosureLabel id
1202 -- This case catches those pesky static closures for nullary constructors
1204 closureLabelFromCI (MkClosureInfo id _ other_rep) = mkClosureLabel id
1206 entryLabelFromCI :: ClosureInfo -> CLabel
1207 entryLabelFromCI (MkClosureInfo id lf_info rep)
1209 LFThunk _ _ upd_flag std_form_info -> thunkEntryLabel id std_form_info upd_flag
1210 LFCon con _ -> mkConEntryPtr con rep
1211 LFTuple tup _ -> mkConEntryPtr tup rep
1212 other -> mkStdEntryLabel id
1214 -- thunkEntryLabel is a local help function, not exported. It's used from both
1215 -- entryLabelFromCI and getEntryConvention.
1216 -- I don't think it needs to deal with the SelectorThunk case
1217 -- Well, it's falling over now, so I've made it deal with it. (JSM)
1219 thunkEntryLabel thunk_id (VapThunk fun_id args _) is_updatable
1220 = mkVapEntryLabel fun_id is_updatable
1221 thunkEntryLabel thunk_id _ is_updatable
1222 = mkStdEntryLabel thunk_id
1226 allocProfilingMsg :: ClosureInfo -> FAST_STRING
1228 allocProfilingMsg (MkClosureInfo _ lf_info _)
1230 LFReEntrant _ _ _ -> SLIT("ALLOC_FUN")
1231 LFCon _ _ -> SLIT("ALLOC_CON")
1232 LFTuple _ _ -> SLIT("ALLOC_CON")
1233 LFThunk _ _ _ _ -> SLIT("ALLOC_THK")
1234 LFBlackHole -> SLIT("ALLOC_BH")
1235 LFImported -> panic "ALLOC_IMP"
1238 We need a black-hole closure info to pass to @allocDynClosure@ when we
1239 want to allocate the black hole on entry to a CAF.
1242 blackHoleClosureInfo (MkClosureInfo id _ _)
1243 = MkClosureInfo id LFBlackHole BlackHoleRep
1246 The register liveness when returning from a constructor. For
1247 simplicity, we claim just [node] is live for all but PhantomRep's. In
1248 truth, this means that non-constructor info tables also claim node,
1249 but since their liveness information is never used, we don't care.
1252 dataConLiveness (MkClosureInfo con _ PhantomRep)
1253 = case (dataReturnConvAlg con) of
1254 ReturnInRegs regs -> mkLiveRegsMask regs
1255 ReturnInHeap -> panic "dataConLiveness:PhantomRep in heap???"
1257 dataConLiveness _ = mkLiveRegsMask [node]
1260 %************************************************************************
1262 \subsection[ClosureInfo-Profiling-funs]{Misc functions about for profiling info.}
1264 %************************************************************************
1266 Profiling requires three pices of information to be determined for
1267 each closure's info table --- kind, description and type.
1269 The description is stored directly in the @CClosureInfoTable@ when the
1270 info table is built.
1272 The kind is determined from the @LambdaForm@ stored in the closure
1273 info using @closureKind@.
1275 The type is determined from the type information stored with the @Id@
1276 in the closure info using @closureTypeDescr@.
1279 closureKind :: ClosureInfo -> String
1281 closureKind (MkClosureInfo _ lf _)
1283 LFReEntrant _ n _ -> if n > 0 then "FN_K" else "THK_K"
1284 LFCon _ _ -> "CON_K"
1285 LFTuple _ _ -> "CON_K"
1286 LFThunk _ _ _ _ -> "THK_K"
1287 LFBlackHole -> "THK_K" -- consider BHs as thunks for the moment... (ToDo?)
1288 LFImported -> panic "IMP_KIND"
1290 closureTypeDescr :: ClosureInfo -> String
1291 closureTypeDescr (MkClosureInfo id lf _)
1292 = if (isDataCon id) then -- DataCon has function types
1293 getOccString (dataConTyCon id) -- We want the TyCon not the ->
1295 getTyDescription (idType id)