2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 % $Id: CgClosure.lhs,v 1.36 1999/11/01 17:10:07 simonpj Exp $
6 \section[CgClosure]{Code generation for closures}
8 This module provides the support code for @StgToAbstractC@ to deal
9 with {\em closures} on the RHSs of let(rec)s. See also
10 @CgCon@, which deals with constructors.
13 module CgClosure ( cgTopRhsClosure,
16 closureCodeBody ) where
18 #include "HsVersions.h"
20 import {-# SOURCE #-} CgExpr ( cgExpr )
26 import AbsCUtils ( mkAbstractCs, getAmodeRep )
27 import CgBindery ( getCAddrMode, getArgAmodes,
28 getCAddrModeAndInfo, bindNewToNode,
30 bindNewToReg, bindArgsToRegs,
31 stableAmodeIdInfo, heapIdInfo, CgIdInfo
33 import CgUpdate ( pushUpdateFrame )
34 import CgHeapery ( allocDynClosure,
35 fetchAndReschedule, yield, -- HWL
36 fastEntryChecks, thunkChecks
38 import CgStackery ( mkTaggedVirtStkOffsets, freeStackSlots )
39 import CgUsages ( adjustSpAndHp, setRealAndVirtualSp, getVirtSp,
40 getSpRelOffset, getHpRelOffset
42 import CLabel ( CLabel, mkClosureLabel, mkFastEntryLabel,
43 mkRednCountsLabel, mkInfoTableLabel
45 import ClosureInfo -- lots and lots of stuff
46 import CmdLineOpts ( opt_GranMacros, opt_SccProfilingOn, opt_DoTickyProfiling )
48 import Id ( Id, idName, idType, idPrimRep )
49 import Name ( Name, isLocalName )
50 import Module ( Module, pprModule )
51 import ListSetOps ( minusList )
52 import PrimRep ( PrimRep(..) )
53 import PprType ( showTypeCategory )
55 import CmdLineOpts ( opt_SccProfilingOn )
58 import Name ( nameOccName )
59 import OccName ( occNameFS )
61 getWrapperArgTypeCategories = panic "CgClosure.getWrapperArgTypeCategories (ToDo)"
64 %********************************************************
66 \subsection[closures-no-free-vars]{Top-level closures}
68 %********************************************************
70 For closures bound at top level, allocate in static space.
71 They should have no free variables.
75 -> CostCentreStack -- Optional cost centre annotation
80 -> FCode (Id, CgIdInfo)
82 cgTopRhsClosure id ccs binder_info args body lf_info
83 = -- LAY OUT THE OBJECT
85 closure_info = layOutStaticNoFVClosure name lf_info
88 -- BUILD THE OBJECT (IF NECESSARY)
89 ({- if staticClosureRequired name binder_info lf_info
91 (if opt_SccProfilingOn
94 closure_label -- Labelled with the name on lhs of defn
96 (mkCCostCentreStack ccs)
100 closure_label -- Labelled with the name on lhs of defn
110 -- GENERATE THE INFO TABLE (IF NECESSARY)
111 forkClosureBody (closureCodeBody binder_info closure_info
116 returnFC (id, cg_id_info)
119 closure_label = mkClosureLabel name
120 cg_id_info = stableAmodeIdInfo id (CLbl closure_label PtrRep) lf_info
123 %********************************************************
125 \subsection[non-top-level-closures]{Non top-level closures}
127 %********************************************************
129 For closures with free vars, allocate in heap.
134 -> CostCentreStack -- Optional cost centre annotation
140 -> [StgArg] -- payload
141 -> FCode (Id, CgIdInfo)
143 cgStdRhsClosure binder cc binder_info fvs args body lf_info payload
144 -- AHA! A STANDARD-FORM THUNK
146 -- LAY OUT THE OBJECT
147 getArgAmodes payload `thenFC` \ amodes ->
149 (closure_info, amodes_w_offsets)
150 = layOutDynClosure (idName binder) getAmodeRep amodes lf_info
152 (use_cc, blame_cc) = chooseDynCostCentres cc args fvs body
155 allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
157 `thenFC` \ heap_offset ->
160 returnFC (binder, heapIdInfo binder heap_offset lf_info)
163 is_std_thunk = isStandardFormThunk lf_info
166 Here's the general case.
170 -> CostCentreStack -- Optional cost centre annotation
176 -> FCode (Id, CgIdInfo)
178 cgRhsClosure binder cc binder_info fvs args body lf_info
180 -- LAY OUT THE OBJECT
182 -- If the binder is itself a free variable, then don't store
183 -- it in the closure. Instead, just bind it to Node on entry.
184 -- NB we can be sure that Node will point to it, because we
185 -- havn't told mkClosureLFInfo about this; so if the binder
186 -- *was* a free var of its RHS, mkClosureLFInfo thinks it *is*
187 -- stored in the closure itself, so it will make sure that
188 -- Node points to it...
190 is_elem = isIn "cgRhsClosure"
192 binder_is_a_fv = binder `is_elem` fvs
193 reduced_fvs = if binder_is_a_fv
194 then fvs `minusList` [binder]
197 mapFCs getCAddrModeAndInfo reduced_fvs `thenFC` \ amodes_and_info ->
199 fvs_w_amodes_and_info = reduced_fvs `zip` amodes_and_info
201 closure_info :: ClosureInfo
202 bind_details :: [((Id, (CAddrMode, LambdaFormInfo)), VirtualHeapOffset)]
204 (closure_info, bind_details)
205 = layOutDynClosure (idName binder) get_kind fvs_w_amodes_and_info lf_info
207 bind_fv ((id, (_, lf_info)), offset) = bindNewToNode id offset lf_info
209 amodes_w_offsets = [(amode,offset) | ((_, (amode,_)), offset) <- bind_details]
211 get_kind (id, amode_and_info) = idPrimRep id
213 -- BUILD ITS INFO TABLE AND CODE
216 mapCs bind_fv bind_details `thenC`
218 -- Bind the binder itself, if it is a free var
219 (if binder_is_a_fv then
220 bindNewToReg binder node lf_info
225 closureCodeBody binder_info closure_info cc args body
230 (use_cc, blame_cc) = chooseDynCostCentres cc args fvs body
232 allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
233 ) `thenFC` \ heap_offset ->
236 returnFC (binder, heapIdInfo binder heap_offset lf_info)
239 %************************************************************************
241 \subsection[code-for-closures]{The code for closures}
243 %************************************************************************
246 closureCodeBody :: StgBinderInfo
247 -> ClosureInfo -- Lots of information about this closure
248 -> CostCentreStack -- Optional cost centre attached to closure
254 There are two main cases for the code for closures. If there are {\em
255 no arguments}, then the closure is a thunk, and not in normal form.
256 So it should set up an update frame (if it is shared). Also, it has
257 no argument satisfaction check, so fast and slow entry-point labels
261 closureCodeBody binder_info closure_info cc [] body
262 = -- thunks cannot have a primitive type!
263 getAbsC body_code `thenFC` \ body_absC ->
264 moduleName `thenFC` \ mod_name ->
266 absC (CClosureInfoAndCode closure_info body_absC Nothing
269 cl_descr mod_name = closureDescription mod_name (closureName closure_info)
271 body_label = entryLabelFromCI closure_info
272 is_box = case body of { StgApp fun [] -> True; _ -> False }
274 body_code = profCtrC SLIT("TICK_ENT_THK") [] `thenC`
275 thunkWrapper closure_info body_label (
276 -- We only enter cc after setting up update so that cc
277 -- of enclosing scope will be recorded in update frame
278 -- CAF/DICT functions will be subsumed by this enclosing cc
279 enterCostCentreCode closure_info cc IsThunk is_box `thenC`
283 If there is {\em at least one argument}, then this closure is in
284 normal form, so there is no need to set up an update frame. On the
285 other hand, we do have to check that there are enough args, and
286 perform an update if not!
288 The Macros for GrAnSim are produced at the beginning of the
289 argSatisfactionCheck (by calling fetchAndReschedule). There info if
290 Node points to closure is available. -- HWL
293 closureCodeBody binder_info closure_info cc all_args body
294 = getEntryConvention name lf_info
295 (map idPrimRep all_args) `thenFC` \ entry_conv ->
297 -- get the current virtual Sp (it might not be zero, eg. if we're
298 -- compiling a let-no-escape).
299 getVirtSp `thenFC` \vSp ->
302 -- Figure out what is needed and what isn't
304 -- SDM: need everything for now in case the heap/stack check refers
306 slow_code_needed = True
307 --slowFunEntryCodeRequired name binder_info entry_conv
308 info_table_needed = True
309 --funInfoTableRequired name binder_info lf_info
311 -- Arg mapping for standard (slow) entry point; all args on stack,
313 (sp_all_args, arg_offsets, arg_tags)
314 = mkTaggedVirtStkOffsets vSp idPrimRep all_args
316 -- Arg mapping for the fast entry point; as many args as poss in
317 -- registers; the rest on the stack
318 -- arg_regs are the registers used for arg passing
319 -- stk_args are the args which are passed on the stack
321 -- Args passed on the stack are tagged, but the tags may not
322 -- actually be present (just gaps) if the function is called
323 -- by jumping directly to the fast entry point.
325 arg_regs = case entry_conv of
326 DirectEntry lbl arity regs -> regs
327 other -> panic "closureCodeBody:arg_regs"
329 num_arg_regs = length arg_regs
331 (reg_args, stk_args) = splitAt num_arg_regs all_args
333 (sp_stk_args, stk_offsets, stk_tags)
334 = mkTaggedVirtStkOffsets vSp idPrimRep stk_args
336 -- HWL; Note: empty list of live regs in slow entry code
337 -- Old version (reschedule combined with heap check);
338 -- see argSatisfactionCheck for new version
339 --slow_entry_code = forceHeapCheck [node] True slow_entry_code'
340 -- where node = UnusedReg PtrRep 1
341 --slow_entry_code = forceHeapCheck [] True slow_entry_code'
344 = profCtrC SLIT("TICK_ENT_FUN_STD") [] `thenC`
346 -- Bind args, and record expected position of stk ptrs
347 mapCs bindNewToStack arg_offsets `thenC`
348 setRealAndVirtualSp sp_all_args `thenC`
350 argSatisfactionCheck closure_info `thenC`
352 -- OK, so there are enough args. Now we need to stuff as
353 -- many of them in registers as the fast-entry code
354 -- expects. Note that the zipWith will give up when it hits
355 -- the end of arg_regs.
357 mapFCs getCAddrMode all_args `thenFC` \ stk_amodes ->
358 absC (mkAbstractCs (zipWith assign_to_reg arg_regs stk_amodes))
361 -- Now adjust real stack pointers (no need to adjust Hp,
362 -- but call this function for convenience).
363 adjustSpAndHp sp_stk_args `thenC`
365 absC (CFallThrough (CLbl fast_label CodePtrRep))
367 assign_to_reg reg_id amode = CAssign (CReg reg_id) amode
370 -- Old version (reschedule combined with heap check);
371 -- see argSatisfactionCheck for new version
372 -- fast_entry_code = forceHeapCheck [] True fast_entry_code'
375 = moduleName `thenFC` \ mod_name ->
376 profCtrC SLIT("TICK_CTR") [
377 CLbl ticky_ctr_label DataPtrRep,
378 mkCString (_PK_ (ppr_for_ticky_name mod_name name)),
379 mkIntCLit stg_arity, -- total # of args
380 mkIntCLit sp_stk_args, -- # passed on stk
381 mkCString (_PK_ (map (showTypeCategory . idType) all_args))
384 profCtrC SLIT("TICK_ENT_FUN_DIRECT") [
385 CLbl ticky_ctr_label DataPtrRep
388 -- Nuked for now; see comment at end of file
389 -- CString (_PK_ (show_wrapper_name wrapper_maybe)),
390 -- CString (_PK_ (show_wrapper_arg_kinds wrapper_maybe))
393 -- Bind args to regs/stack as appropriate, and
394 -- record expected position of sps.
395 bindArgsToRegs reg_args arg_regs `thenC`
396 mapCs bindNewToStack stk_offsets `thenC`
397 setRealAndVirtualSp sp_stk_args `thenC`
399 -- free up the stack slots containing tags
400 freeStackSlots (map fst stk_tags) `thenC`
402 -- Enter the closures cc, if required
403 enterCostCentreCode closure_info cc IsFunction False `thenC`
406 funWrapper closure_info arg_regs stk_tags info_label (cgExpr body)
409 setTickyCtrLabel ticky_ctr_label (
411 -- Make a labelled code-block for the slow and fast entry code
412 forkAbsC (if slow_code_needed then slow_entry_code else absC AbsCNop)
413 `thenFC` \ slow_abs_c ->
414 forkAbsC fast_entry_code `thenFC` \ fast_abs_c ->
415 moduleName `thenFC` \ mod_name ->
417 -- Now either construct the info table, or put the fast code in alone
418 -- (We never have slow code without an info table)
419 -- XXX probably need the info table and slow entry code in case of
420 -- a heap check failure.
422 if info_table_needed then
423 CClosureInfoAndCode closure_info slow_abs_c (Just fast_abs_c)
426 CCodeBlock fast_label fast_abs_c
430 ticky_ctr_label = mkRednCountsLabel name
432 stg_arity = length all_args
433 lf_info = closureLFInfo closure_info
435 cl_descr mod_name = closureDescription mod_name name
437 -- Manufacture labels
438 name = closureName closure_info
439 fast_label = mkFastEntryLabel name stg_arity
440 info_label = mkInfoTableLabel name
443 -- When printing the name of a thing in a ticky file, we want to
444 -- give the module name even for *local* things. We print
445 -- just "x (M)" rather that "M.x" to distinguish them from the global kind.
446 ppr_for_ticky_name mod_name name
447 | isLocalName name = showSDocDebug (ppr name <+> (parens (ppr mod_name)))
448 | otherwise = showSDocDebug (ppr name)
451 For lexically scoped profiling we have to load the cost centre from
452 the closure entered, if the costs are not supposed to be inherited.
453 This is done immediately on entering the fast entry point.
455 Load current cost centre from closure, if not inherited.
456 Node is guaranteed to point to it, if profiling and not inherited.
459 data IsThunk = IsThunk | IsFunction -- Bool-like, local
465 :: ClosureInfo -> CostCentreStack
467 -> Bool -- is_box: this closure is a special box introduced by SCCfinal
470 enterCostCentreCode closure_info ccs is_thunk is_box
471 = if not opt_SccProfilingOn then
474 ASSERT(not (noCCSAttached ccs))
476 if isSubsumedCCS ccs then
477 ASSERT(isToplevClosure closure_info)
478 ASSERT(is_thunk == IsFunction)
479 costCentresC SLIT("ENTER_CCS_FSUB") []
481 else if isCurrentCCS ccs then
482 if re_entrant && not is_box
483 then costCentresC SLIT("ENTER_CCS_FCL") [CReg node]
484 else costCentresC SLIT("ENTER_CCS_TCL") [CReg node]
486 else if isCafCCS ccs then
487 ASSERT(isToplevClosure closure_info)
488 ASSERT(is_thunk == IsThunk)
489 -- might be a PAP, in which case we want to subsume costs
491 then costCentresC SLIT("ENTER_CCS_FSUB") []
492 else costCentresC SLIT("ENTER_CCS_CAF") c_ccs
494 else panic "enterCostCentreCode"
497 c_ccs = [mkCCostCentreStack ccs]
498 re_entrant = closureReEntrant closure_info
501 %************************************************************************
503 \subsubsection[pre-closure-code-stuff]{Pre-closure-code code}
505 %************************************************************************
507 The argument-satisfaction check code is placed after binding
508 the arguments to their stack locations. Hence, the virtual stack
509 pointer is pointing after all the args, and virtual offset 1 means
510 the base of frame and hence most distant arg. Hence
511 virtual offset 0 is just beyond the most distant argument; the
512 relative offset of this word tells how many words of arguments
516 argSatisfactionCheck :: ClosureInfo -> Code
518 argSatisfactionCheck closure_info
520 = nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
523 emit_gran_macros = opt_GranMacros
527 -- absC (CMacroStmt GRAN_FETCH []) `thenC`
528 -- forceHeapCheck [] node_points (absC AbsCNop) `thenC`
531 then fetchAndReschedule [] node_points
532 else yield [] node_points
533 else absC AbsCNop) `thenC`
535 getSpRelOffset 0 `thenFC` \ (SpRel sp) ->
538 rel_arg = mkIntCLit off
542 absC (CMacroStmt ARGS_CHK [rel_arg]) -- node already points
544 absC (CMacroStmt ARGS_CHK_LOAD_NODE [rel_arg, set_Node_to_this])
546 -- We must tell the arg-satis macro whether Node is pointing to
547 -- the closure or not. If it isn't so pointing, then we give to
548 -- the macro the (static) address of the closure.
550 set_Node_to_this = CLbl (closureLabelFromCI closure_info) PtrRep
553 %************************************************************************
555 \subsubsection[closure-code-wrappers]{Wrappers around closure code}
557 %************************************************************************
560 thunkWrapper:: ClosureInfo -> CLabel -> Code -> Code
561 thunkWrapper closure_info lbl thunk_code
562 = -- Stack and heap overflow checks
563 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
566 emit_gran_macros = opt_GranMacros
568 -- HWL: insert macros for GrAnSim; 2 versions depending on liveness of node
569 -- (we prefer fetchAndReschedule-style context switches to yield ones)
572 then fetchAndReschedule [] node_points
573 else yield [] node_points
574 else absC AbsCNop) `thenC`
576 -- stack and/or heap checks
577 thunkChecks lbl node_points (
579 -- Overwrite with black hole if necessary
580 blackHoleIt closure_info node_points `thenC`
582 setupUpdate closure_info ( -- setupUpdate *encloses* the rest
584 -- Finally, do the business
588 funWrapper :: ClosureInfo -- Closure whose code body this is
589 -> [MagicId] -- List of argument registers (if any)
590 -> [(VirtualSpOffset,Int)] -- tagged stack slots
591 -> CLabel -- info table for heap check ret.
592 -> Code -- Body of function being compiled
594 funWrapper closure_info arg_regs stk_tags info_label fun_body
595 = -- Stack overflow check
596 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
598 emit_gran_macros = opt_GranMacros
602 then yield arg_regs node_points
603 else absC AbsCNop) `thenC`
605 -- heap and/or stack checks
606 fastEntryChecks arg_regs stk_tags info_label node_points (
608 -- Finally, do the business
614 %************************************************************************
616 \subsubsubsection[update-and-BHs]{Update and black-hole wrappers}
618 %************************************************************************
622 blackHoleIt :: ClosureInfo -> Bool -> Code -- Only called for closures with no args
624 blackHoleIt closure_info node_points
625 = if blackHoleOnEntry closure_info && node_points
627 absC (if closureSingleEntry(closure_info) then
628 CMacroStmt UPD_BH_SINGLE_ENTRY [CReg node]
630 CMacroStmt UPD_BH_UPDATABLE [CReg node])
636 setupUpdate :: ClosureInfo -> Code -> Code -- Only called for closures with no args
637 -- Nota Bene: this function does not change Node (even if it's a CAF),
638 -- so that the cost centre in the original closure can still be
639 -- extracted by a subsequent ENTER_CC_TCL
641 -- I've tidied up the code for this function, but it should still do the same as
642 -- it did before (modulo ticky stuff). KSW 1999-04.
643 setupUpdate closure_info code
644 = if closureReEntrant closure_info
648 case (closureUpdReqd closure_info, isStaticClosure closure_info) of
649 (False,False) -> profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
651 (False,True ) -> (if opt_DoTickyProfiling
653 -- blackhole the SE CAF
654 link_caf seCafBlackHoleClosureInfo `thenFC` \ _ -> nopC
657 profCtrC SLIT("TICK_UPD_CAF_BH_SINGLE_ENTRY") [mkCString cl_name] `thenC`
658 profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
660 (True ,False) -> pushUpdateFrame (CReg node) code
661 (True ,True ) -> -- blackhole the (updatable) CAF:
662 link_caf cafBlackHoleClosureInfo `thenFC` \ update_closure ->
663 profCtrC SLIT("TICK_UPD_CAF_BH_UPDATABLE") [mkCString cl_name] `thenC`
664 pushUpdateFrame update_closure code
666 cl_name :: FAST_STRING
667 cl_name = (occNameFS . nameOccName . closureName) closure_info
669 link_caf :: (ClosureInfo -> ClosureInfo) -- function yielding BH closure_info
670 -> FCode CAddrMode -- Returns amode for closure to be updated
672 = -- To update a CAF we must allocate a black hole, link the CAF onto the
673 -- CAF list, then update the CAF to point to the fresh black hole.
674 -- This function returns the address of the black hole, so it can be
675 -- updated with the new value when available.
677 -- Alloc black hole specifying CC_HDR(Node) as the cost centre
678 -- Hack Warning: Using a CLitLit to get CAddrMode !
680 use_cc = CLitLit SLIT("CCS_HDR(R1.p)") PtrRep
683 allocDynClosure (bhCI closure_info) use_cc blame_cc [] `thenFC` \ heap_offset ->
684 getHpRelOffset heap_offset `thenFC` \ hp_rel ->
685 let amode = CAddr hp_rel
687 absC (CMacroStmt UPD_CAF [CReg node, amode]) `thenC`
691 %************************************************************************
693 \subsection[CgClosure-Description]{Profiling Closure Description.}
695 %************************************************************************
697 For "global" data constructors the description is simply occurrence
698 name of the data constructor itself (see \ref{CgConTbls-info-tables}).
700 Otherwise it is determind by @closureDescription@ from the let
704 closureDescription :: Module -- Module
705 -> Name -- Id of closure binding
708 -- Not called for StgRhsCon which have global info tables built in
709 -- CgConTbls.lhs with a description generated from the data constructor
711 closureDescription mod_name name
721 chooseDynCostCentres ccs args fvs body
723 use_cc -- cost-centre we record in the object
724 = if currentOrSubsumedCCS ccs
725 then CReg CurCostCentre
726 else mkCCostCentreStack ccs
728 blame_cc -- cost-centre on whom we blame the allocation
729 = case (args, fvs, body) of
730 ([], _, StgApp fun [{-no args-}])
731 -> mkCCostCentreStack overheadCCS
734 -- if it's an utterly trivial RHS, then it must be
735 -- one introduced by boxHigherOrderArgs for profiling,
736 -- so we charge it to "OVERHEAD".
738 -- This looks like a HACK to me --SDM
745 ========================================================================
746 OLD CODE THAT EMITTED INFORMATON FOR QUANTITATIVE ANALYSIS
748 It's pretty wierd, so I've nuked it for now. SLPJ Nov 96
751 getWrapperArgTypeCategories
752 :: Type -- wrapper's type
753 -> StrictnessInfo bdee -- strictness info about its args
756 getWrapperArgTypeCategories _ NoStrictnessInfo = Nothing
757 getWrapperArgTypeCategories _ BottomGuaranteed
758 = trace "getWrapperArgTypeCategories:BottomGuaranteed!" Nothing -- wrong
759 getWrapperArgTypeCategories _ (StrictnessInfo [] _) = Nothing
761 getWrapperArgTypeCategories ty (StrictnessInfo arg_info _)
762 = Just (mkWrapperArgTypeCategories ty arg_info)
764 mkWrapperArgTypeCategories
765 :: Type -- wrapper's type
766 -> [Demand] -- info about its arguments
767 -> String -- a string saying lots about the args
769 mkWrapperArgTypeCategories wrapper_ty wrap_info
770 = case (splitFunTy_maybe wrapper_ty) of { Just (arg_tys,_) ->
771 map do_one (wrap_info `zip` (map showTypeCategory arg_tys)) }
773 -- ToDo: this needs FIXING UP (it was a hack anyway...)
774 do_one (WwPrim, _) = 'P'
775 do_one (WwEnum, _) = 'E'
776 do_one (WwStrict, arg_ty_char) = arg_ty_char
777 do_one (WwUnpack _ _ _, arg_ty_char)
778 = if arg_ty_char `elem` "CIJFDTS"
779 then toLower arg_ty_char
780 else if arg_ty_char == '+' then 't'
781 else trace ("mkWrapp..:funny char:"++[arg_ty_char]) '-'
782 do_one (other_wrap_info, _) = '-'