2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
4 \section[CgClosure]{Code generation for closures}
6 This module provides the support code for @StgToAbstractC@ to deal
7 with {\em closures} on the RHSs of let(rec)s. See also
8 @CgCon@, which deals with constructors.
11 #include "HsVersions.h"
13 module CgClosure ( cgTopRhsClosure, cgRhsClosure ) where
16 import CgLoop2 ( cgExpr, cgSccExpr )
22 import AbsCUtils ( mkAbstractCs, getAmodeRep )
23 import CgBindery ( getCAddrMode, getArgAmodes,
24 getCAddrModeAndInfo, bindNewToNode,
25 bindNewToAStack, bindNewToBStack,
26 bindNewToReg, bindArgsToRegs,
27 stableAmodeIdInfo, heapIdInfo
29 import CgCompInfo ( spARelToInt, spBRelToInt )
30 import CgUpdate ( pushUpdateFrame )
31 import CgHeapery ( allocDynClosure, heapCheck
33 , fetchAndReschedule -- HWL
36 import CgRetConv ( mkLiveRegsMask,
37 ctrlReturnConvAlg, dataReturnConvAlg,
38 CtrlReturnConvention(..), DataReturnConvention(..)
40 import CgStackery ( getFinalStackHW, mkVirtStkOffsets,
43 import CgUsages ( getVirtSps, setRealAndVirtualSps,
44 getSpARelOffset, getSpBRelOffset,
47 import CLabel ( mkClosureLabel, mkConUpdCodePtrVecLabel,
48 mkStdUpdCodePtrVecLabel, mkStdUpdVecTblLabel,
49 mkErrorStdEntryLabel, mkRednCountsLabel
51 import ClosureInfo -- lots and lots of stuff
52 import CmdLineOpts ( opt_EmitArityChecks, opt_ForConcurrent )
53 import CostCentre ( useCurrentCostCentre, currentOrSubsumedCosts,
54 noCostCentreAttached, costsAreSubsumed,
55 isCafCC, overheadCostCentre
57 import HeapOffs ( VirtualHeapOffset(..) )
58 import Id ( idType, idPrimRep,
59 showId, getIdStrictness, dataConTag,
61 GenId{-instance Outputable-}
63 import ListSetOps ( minusList )
64 import Maybes ( maybeToBool )
65 import PprStyle ( PprStyle(..) )
66 import PprType ( GenType{-instance Outputable-}, TyCon{-ditto-} )
67 import Pretty ( prettyToUn, ppBesides, ppChar, ppPStr )
68 import PrimRep ( isFollowableRep, PrimRep(..) )
69 import TyCon ( isPrimTyCon, tyConDataCons )
70 import Unpretty ( uppShow )
71 import Util ( isIn, panic, pprPanic, assertPanic )
73 myWrapperMaybe = panic "CgClosure.myWrapperMaybe (ToDo)"
74 showTypeCategory = panic "CgClosure.showTypeCategory (ToDo)"
75 getWrapperArgTypeCategories = panic "CgClosure.getWrapperArgTypeCategories (ToDo)"
78 %********************************************************
80 \subsection[closures-no-free-vars]{Top-level closures}
82 %********************************************************
84 For closures bound at top level, allocate in static space.
85 They should have no free variables.
89 -> CostCentre -- Optional cost centre annotation
94 -> FCode (Id, CgIdInfo)
96 cgTopRhsClosure name cc binder_info args body lf_info
97 = -- LAY OUT THE OBJECT
99 closure_info = layOutStaticNoFVClosure name lf_info
102 -- GENERATE THE INFO TABLE (IF NECESSARY)
103 forkClosureBody (closureCodeBody binder_info closure_info
107 -- BUILD VAP INFO TABLES IF NECESSARY
108 -- Don't build Vap info tables etc for
109 -- a function whose result is an unboxed type,
110 -- because we can never have thunks with such a type.
111 (if closureReturnsUnboxedType closure_info then
115 bind_the_fun = addBindC name cg_id_info -- It's global!
117 cgVapInfoTables True {- Top level -} bind_the_fun binder_info name args lf_info
120 -- BUILD THE OBJECT (IF NECESSARY)
121 (if staticClosureRequired name binder_info lf_info
124 cost_centre = mkCCostCentre cc
127 closure_label -- Labelled with the name on lhs of defn
135 returnFC (name, cg_id_info)
137 closure_label = mkClosureLabel name
138 cg_id_info = stableAmodeIdInfo name (CLbl closure_label PtrRep) lf_info
141 %********************************************************
143 \subsection[non-top-level-closures]{Non top-level closures}
145 %********************************************************
147 For closures with free vars, allocate in heap.
149 ===================== OLD PROBABLY OUT OF DATE COMMENTS =============
151 -- Closures which (a) have no fvs and (b) have some args (i.e.
152 -- combinator functions), are allocated statically, just as if they
153 -- were top-level closures. We can't get a space leak that way
154 -- (because they are HNFs) and it saves allocation.
156 -- Lexical Scoping: Problem
157 -- These top level function closures will be inherited, possibly
158 -- to a different cost centre scope set before entering.
160 -- Evaluation Scoping: ok as already in HNF
162 -- Should rely on floating mechanism to achieve this floating to top level.
163 -- As let floating will avoid floating which breaks cost centre attribution
164 -- everything will be OK.
166 -- Disabled: because it breaks lexical-scoped cost centre semantics.
167 -- cgRhsClosure binder cc bi [] upd_flag args@(_:_) body
168 -- = cgTopRhsClosure binder cc bi upd_flag args body
170 ===================== END OF OLD PROBABLY OUT OF DATE COMMENTS =============
174 -> CostCentre -- Optional cost centre annotation
180 -> FCode (Id, CgIdInfo)
182 cgRhsClosure binder cc binder_info fvs args body lf_info
183 | maybeToBool maybe_std_thunk -- AHA! A STANDARD-FORM THUNK
184 -- ToDo: check non-primitiveness (ASSERT)
186 -- LAY OUT THE OBJECT
187 getArgAmodes std_thunk_payload `thenFC` \ amodes ->
189 (closure_info, amodes_w_offsets)
190 = layOutDynClosure binder getAmodeRep amodes lf_info
192 (use_cc, blame_cc) = chooseDynCostCentres cc args fvs body
195 allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
197 `thenFC` \ heap_offset ->
200 returnFC (binder, heapIdInfo binder heap_offset lf_info)
203 maybe_std_thunk = getStandardFormThunkInfo lf_info
204 Just std_thunk_payload = maybe_std_thunk
207 Here's the general case.
209 cgRhsClosure binder cc binder_info fvs args body lf_info
211 -- LAY OUT THE OBJECT
213 -- If the binder is itself a free variable, then don't store
214 -- it in the closure. Instead, just bind it to Node on entry.
215 -- NB we can be sure that Node will point to it, because we
216 -- havn't told mkClosureLFInfo about this; so if the binder
217 -- *was* a free var of its RHS, mkClosureLFInfo thinks it *is*
218 -- stored in the closure itself, so it will make sure that
219 -- Node points to it...
221 is_elem = isIn "cgRhsClosure"
223 binder_is_a_fv = binder `is_elem` fvs
224 reduced_fvs = if binder_is_a_fv
225 then fvs `minusList` [binder]
228 mapFCs getCAddrModeAndInfo reduced_fvs `thenFC` \ amodes_and_info ->
230 fvs_w_amodes_and_info = reduced_fvs `zip` amodes_and_info
232 closure_info :: ClosureInfo
233 bind_details :: [((Id, (CAddrMode, LambdaFormInfo)), VirtualHeapOffset)]
235 (closure_info, bind_details)
236 = layOutDynClosure binder get_kind fvs_w_amodes_and_info lf_info
238 bind_fv ((id, (_, lf_info)), offset) = bindNewToNode id offset lf_info
240 amodes_w_offsets = [(amode,offset) | ((_, (amode,_)), offset) <- bind_details]
242 get_kind (id, amode_and_info) = idPrimRep id
244 -- BUILD ITS INFO TABLE AND CODE
247 mapCs bind_fv bind_details `thenC`
249 -- Bind the binder itself, if it is a free var
250 (if binder_is_a_fv then
251 bindNewToReg binder node lf_info
256 closureCodeBody binder_info closure_info cc args body
259 -- BUILD VAP INFO TABLES IF NECESSARY
260 -- Don't build Vap info tables etc for
261 -- a function whose result is an unboxed type,
262 -- because we can never have thunks with such a type.
263 (if closureReturnsUnboxedType closure_info then
266 cgVapInfoTables False {- Not top level -} nopC binder_info binder args lf_info
271 (use_cc, blame_cc) = chooseDynCostCentres cc args fvs body
273 allocDynClosure closure_info use_cc blame_cc amodes_w_offsets
274 ) `thenFC` \ heap_offset ->
277 returnFC (binder, heapIdInfo binder heap_offset lf_info)
280 @cgVapInfoTables@ generates both Vap info tables, if they are required
281 at all. It calls @cgVapInfoTable@ to generate each Vap info table,
282 along with its entry code.
285 -- Don't generate Vap info tables for thunks; only for functions
286 cgVapInfoTables top_level perhaps_bind_the_fun binder_info fun [{- no args; a thunk! -}] lf_info
289 cgVapInfoTables top_level perhaps_bind_the_fun binder_info fun args lf_info
290 = -- BUILD THE STANDARD VAP-ENTRY STUFF IF NECESSARY
291 (if stdVapRequired binder_info then
292 cgVapInfoTable perhaps_bind_the_fun Updatable fun args fun_in_payload lf_info
297 -- BUILD THE NO-UPDATE VAP-ENTRY STUFF IF NECESSARY
298 (if noUpdVapRequired binder_info then
299 cgVapInfoTable perhaps_bind_the_fun SingleEntry fun args fun_in_payload lf_info
305 fun_in_payload = not top_level
307 cgVapInfoTable perhaps_bind_the_fun upd_flag fun args fun_in_payload fun_lf_info
309 -- The vap_entry_rhs is a manufactured STG expression which
310 -- looks like the RHS of any binding which is going to use the vap-entry
311 -- point of the function. Each of these bindings will look like:
313 -- x = [a,b,c] \upd [] -> f a b c
315 -- If f is not top-level, then f is one of the free variables too,
316 -- hence "payload_ids" isn't the same as "arg_ids".
318 vap_entry_rhs = StgApp (StgVarArg fun) (map StgVarArg args) emptyIdSet
321 arg_ids_w_info = [(name,mkLFArgument) | name <- args]
322 payload_ids_w_info | fun_in_payload = (fun,fun_lf_info) : arg_ids_w_info
323 | otherwise = arg_ids_w_info
325 payload_ids | fun_in_payload = fun : args -- Sigh; needed for mkClosureLFInfo
328 vap_lf_info = mkClosureLFInfo False {-not top level-} payload_ids
329 upd_flag [] vap_entry_rhs
330 -- It's not top level, even if we're currently compiling a top-level
331 -- function, because any VAP *use* of this function will be for a
333 -- let x = f p q -- x isn't top level!
336 get_kind (id, info) = idPrimRep id
338 payload_bind_details :: [((Id, LambdaFormInfo), VirtualHeapOffset)]
339 (closure_info, payload_bind_details) = layOutDynClosure
341 get_kind payload_ids_w_info
343 -- The dodgy thing is that we use the "fun" as the
344 -- Id to give to layOutDynClosure. This Id gets embedded in
345 -- the closure_info it returns. But of course, the function doesn't
346 -- have the right type to match the Vap closure. Never mind,
347 -- a hack in closureType spots the special case. Otherwise that
348 -- Id is just used for label construction, which is OK.
350 bind_fv ((id,lf_info), offset) = bindNewToNode id offset lf_info
353 -- BUILD ITS INFO TABLE AND CODE
356 -- Bind the fvs; if the fun is not in the payload, then bind_the_fun tells
357 -- how to bind it. If it is in payload it'll be bound by payload_bind_details.
358 perhaps_bind_the_fun `thenC`
359 mapCs bind_fv payload_bind_details `thenC`
361 -- Generate the info table and code
362 closureCodeBody NoStgBinderInfo
365 [] -- No args; it's a thunk
369 %************************************************************************
371 \subsection[code-for-closures]{The code for closures}
373 %************************************************************************
376 closureCodeBody :: StgBinderInfo
377 -> ClosureInfo -- Lots of information about this closure
378 -> CostCentre -- Optional cost centre attached to closure
384 There are two main cases for the code for closures. If there are {\em
385 no arguments}, then the closure is a thunk, and not in normal form.
386 So it should set up an update frame (if it is shared). Also, it has
387 no argument satisfaction check, so fast and slow entry-point labels
391 closureCodeBody binder_info closure_info cc [] body
392 = -- thunks cannot have a primitive type!
396 = case (closureType closure_info) of
397 Nothing -> (False, panic "debug")
398 Just (tc,_,_) -> (True, tc)
400 if has_tycon && isPrimTyCon tycon then
401 pprPanic "closureCodeBody:thunk:prim type!" (ppr PprDebug tycon)
404 getAbsC body_code `thenFC` \ body_absC ->
405 moduleName `thenFC` \ mod_name ->
407 absC (CClosureInfoAndCode closure_info body_absC Nothing
408 stdUpd (cl_descr mod_name)
409 (dataConLiveness closure_info))
411 cl_descr mod_name = closureDescription mod_name (closureId closure_info) [] body
413 body_addr = CLbl (entryLabelFromCI closure_info) CodePtrRep
414 body_code = profCtrC SLIT("ENT_THK") [] `thenC`
415 enterCostCentreCode closure_info cc IsThunk `thenC`
416 thunkWrapper closure_info (cgSccExpr body)
418 stdUpd = CLbl mkErrorStdEntryLabel CodePtrRep
421 If there is {\em at least one argument}, then this closure is in
422 normal form, so there is no need to set up an update frame. On the
423 other hand, we do have to check that there are enough args, and
424 perform an update if not!
426 The Macros for GrAnSim are produced at the beginning of the
427 argSatisfactionCheck (by calling fetchAndReschedule). There info if
428 Node points to closure is available. -- HWL
431 closureCodeBody binder_info closure_info cc all_args body
432 = getEntryConvention id lf_info
433 (map idPrimRep all_args) `thenFC` \ entry_conv ->
435 do_arity_chks = opt_EmitArityChecks
436 is_concurrent = opt_ForConcurrent
438 stg_arity = length all_args
440 -- Arg mapping for standard (slow) entry point; all args on stack
441 (spA_all_args, spB_all_args, all_bxd_w_offsets, all_ubxd_w_offsets)
443 0 0 -- Initial virtual SpA, SpB
447 -- Arg mapping for the fast entry point; as many args as poss in
448 -- registers; the rest on the stack
449 -- arg_regs are the registers used for arg passing
450 -- stk_args are the args which are passed on the stack
452 arg_regs = case entry_conv of
453 DirectEntry lbl arity regs -> regs
454 ViaNode | is_concurrent -> []
455 other -> panic "closureCodeBody:arg_regs"
457 stk_args = drop (length arg_regs) all_args
458 (spA_stk_args, spB_stk_args, stk_bxd_w_offsets, stk_ubxd_w_offsets)
460 0 0 -- Initial virtual SpA, SpB
464 -- HWL; Note: empty list of live regs in slow entry code
465 -- Old version (reschedule combined with heap check);
466 -- see argSatisfactionCheck for new version
467 --slow_entry_code = forceHeapCheck [node] True slow_entry_code'
468 -- where node = VanillaReg PtrRep 1
469 --slow_entry_code = forceHeapCheck [] True slow_entry_code'
472 = profCtrC SLIT("ENT_FUN_STD") [] `thenC`
474 -- Bind args, and record expected position of stk ptrs
475 mapCs bindNewToAStack all_bxd_w_offsets `thenC`
476 mapCs bindNewToBStack all_ubxd_w_offsets `thenC`
477 setRealAndVirtualSps spA_all_args spB_all_args `thenC`
479 argSatisfactionCheck closure_info all_args `thenC`
481 -- OK, so there are enough args. Now we need to stuff as
482 -- many of them in registers as the fast-entry code
483 -- expects Note that the zipWith will give up when it hits
484 -- the end of arg_regs.
486 mapFCs getCAddrMode all_args `thenFC` \ stk_amodes ->
487 absC (mkAbstractCs (zipWith assign_to_reg arg_regs stk_amodes)) `thenC`
489 -- Now adjust real stack pointers
490 adjustRealSps spA_stk_args spB_stk_args `thenC`
492 -- set the arity checker, if asked
495 then CMacroStmt SET_ARITY [mkIntCLit stg_arity]
498 absC (CFallThrough (CLbl fast_label CodePtrRep))
500 assign_to_reg reg_id amode = CAssign (CReg reg_id) amode
503 -- Old version (reschedule combined with heap check);
504 -- see argSatisfactionCheck for new version
505 -- fast_entry_code = forceHeapCheck [] True fast_entry_code'
508 = profCtrC SLIT("ENT_FUN_DIRECT") [
509 CLbl (mkRednCountsLabel id) PtrRep,
510 CString (_PK_ (showId PprDebug id)),
511 mkIntCLit stg_arity, -- total # of args
512 mkIntCLit spA_stk_args, -- # passed on A stk
513 mkIntCLit spB_stk_args, -- B stk (rest in regs)
514 CString (_PK_ (map (showTypeCategory . idType) all_args)),
515 CString (_PK_ (show_wrapper_name wrapper_maybe)),
516 CString (_PK_ (show_wrapper_arg_kinds wrapper_maybe))
520 then CMacroStmt CHK_ARITY [mkIntCLit stg_arity]
524 -- Bind args to regs/stack as appropriate, and
525 -- record expected position of sps
526 bindArgsToRegs all_args arg_regs `thenC`
527 mapCs bindNewToAStack stk_bxd_w_offsets `thenC`
528 mapCs bindNewToBStack stk_ubxd_w_offsets `thenC`
529 setRealAndVirtualSps spA_stk_args spB_stk_args `thenC`
531 -- Enter the closures cc, if required
532 enterCostCentreCode closure_info cc IsFunction `thenC`
535 funWrapper closure_info arg_regs (cgExpr body)
537 -- Make a labelled code-block for the slow and fast entry code
538 forkAbsC (if slow_code_needed then slow_entry_code else absC AbsCNop)
539 `thenFC` \ slow_abs_c ->
540 forkAbsC fast_entry_code `thenFC` \ fast_abs_c ->
541 moduleName `thenFC` \ mod_name ->
543 -- Now either construct the info table, or put the fast code in alone
544 -- (We never have slow code without an info table)
546 if info_table_needed then
547 CClosureInfoAndCode closure_info slow_abs_c (Just fast_abs_c)
548 stdUpd (cl_descr mod_name)
549 (dataConLiveness closure_info)
551 CCodeBlock fast_label fast_abs_c
554 lf_info = closureLFInfo closure_info
556 cl_descr mod_name = closureDescription mod_name id all_args body
558 -- Figure out what is needed and what isn't
559 slow_code_needed = slowFunEntryCodeRequired id binder_info
560 info_table_needed = funInfoTableRequired id binder_info lf_info
562 -- Manufacture labels
563 id = closureId closure_info
565 fast_label = fastLabelFromCI closure_info
567 stdUpd = CLbl mkErrorStdEntryLabel CodePtrRep
569 wrapper_maybe = get_ultimate_wrapper Nothing id
571 get_ultimate_wrapper deflt x -- walk all the way up a "wrapper chain"
572 = case (myWrapperMaybe x) of
574 Just xx -> get_ultimate_wrapper (Just xx) xx
576 show_wrapper_name Nothing = ""
577 show_wrapper_name (Just xx) = showId PprDebug xx
579 show_wrapper_arg_kinds Nothing = ""
580 show_wrapper_arg_kinds (Just xx)
581 = case (getWrapperArgTypeCategories (idType xx) (getIdStrictness xx)) of
586 For lexically scoped profiling we have to load the cost centre from
587 the closure entered, if the costs are not supposed to be inherited.
588 This is done immediately on entering the fast entry point.
590 Load current cost centre from closure, if not inherited.
591 Node is guaranteed to point to it, if profiling and not inherited.
594 data IsThunk = IsThunk | IsFunction -- Bool-like, local
596 enterCostCentreCode :: ClosureInfo -> CostCentre -> IsThunk -> Code
598 enterCostCentreCode closure_info cc is_thunk
599 = costCentresFlag `thenFC` \ profiling_on ->
600 if not profiling_on then
602 else -- down to business
603 ASSERT(not (noCostCentreAttached cc))
605 if costsAreSubsumed cc then
608 else if is_current_CC cc then -- fish the CC out of the closure,
609 -- where we put it when we alloc'd;
610 -- NB: chk defn of "is_current_CC"
611 -- if you go to change this! (WDP 94/12)
614 IsThunk -> SLIT("ENTER_CC_TCL")
615 IsFunction -> SLIT("ENTER_CC_FCL"))
618 else if isCafCC cc then
623 else -- we've got a "real" cost centre right here in our hands...
626 IsThunk -> SLIT("ENTER_CC_T")
627 IsFunction -> SLIT("ENTER_CC_F"))
631 = currentOrSubsumedCosts cc
632 -- but we've already ruled out "subsumed", so it must be "current"!
635 %************************************************************************
637 \subsubsection[pre-closure-code-stuff]{Pre-closure-code code}
639 %************************************************************************
641 The argument-satisfaction check code is placed after binding
642 the arguments to their stack locations. Hence, the virtual stack
643 pointer is pointing after all the args, and virtual offset 1 means
644 the base of frame and hence most distant arg. Hence
645 virtual offset 0 is just beyond the most distant argument; the
646 relative offset of this word tells how many words of arguments
650 argSatisfactionCheck :: ClosureInfo -> [Id] -> Code
652 argSatisfactionCheck closure_info [] = nopC
654 argSatisfactionCheck closure_info args
655 = -- safest way to determine which stack last arg will be on:
656 -- look up CAddrMode that last arg is bound to;
658 -- check isFollowableRep.
660 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
664 -- absC (CMacroStmt GRAN_FETCH []) `thenC`
665 -- forceHeapCheck [] node_points (absC AbsCNop) `thenC`
667 then fetchAndReschedule [] node_points
668 else absC AbsCNop) `thenC`
671 getCAddrMode (last args) `thenFC` \ last_amode ->
673 if (isFollowableRep (getAmodeRep last_amode)) then
674 getSpARelOffset 0 `thenFC` \ (SpARel spA off) ->
676 lit = mkIntCLit (spARelToInt spA off)
679 absC (CMacroStmt ARGS_CHK_A [lit])
681 absC (CMacroStmt ARGS_CHK_A_LOAD_NODE [lit, set_Node_to_this])
683 getSpBRelOffset 0 `thenFC` \ (SpBRel spB off) ->
685 lit = mkIntCLit (spBRelToInt spB off)
688 absC (CMacroStmt ARGS_CHK_B [lit])
690 absC (CMacroStmt ARGS_CHK_B_LOAD_NODE [lit, set_Node_to_this])
692 -- We must tell the arg-satis macro whether Node is pointing to
693 -- the closure or not. If it isn't so pointing, then we give to
694 -- the macro the (static) address of the closure.
696 set_Node_to_this = CLbl (closureLabelFromCI closure_info) PtrRep
699 %************************************************************************
701 \subsubsection[closure-code-wrappers]{Wrappers around closure code}
703 %************************************************************************
706 thunkWrapper:: ClosureInfo -> Code -> Code
707 thunkWrapper closure_info thunk_code
708 = -- Stack and heap overflow checks
709 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
712 -- HWL insert macros for GrAnSim if node is live here
714 then fetchAndReschedule [] node_points
715 else absC AbsCNop) `thenC`
718 stackCheck closure_info [] node_points ( -- stackCheck *encloses* the rest
720 -- Must be after stackCheck: if stchk fails new stack
721 -- space has to be allocated from the heap
723 heapCheck [] node_points (
724 -- heapCheck *encloses* the rest
725 -- The "[]" says there are no live argument registers
727 -- Overwrite with black hole if necessary
728 blackHoleIt closure_info `thenC`
730 -- Push update frame if necessary
731 setupUpdate closure_info ( -- setupUpdate *encloses* the rest
735 funWrapper :: ClosureInfo -- Closure whose code body this is
736 -> [MagicId] -- List of argument registers (if any)
737 -> Code -- Body of function being compiled
739 funWrapper closure_info arg_regs fun_body
740 = -- Stack overflow check
741 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
742 stackCheck closure_info arg_regs node_points ( -- stackCheck *encloses* the rest
744 -- Heap overflow check
745 heapCheck arg_regs node_points (
746 -- heapCheck *encloses* the rest
748 -- Finally, do the business
753 %************************************************************************
755 \subsubsubsection[overflow-checks]{Stack and heap overflow wrappers}
757 %************************************************************************
759 Assumption: virtual and real stack pointers are currently exactly aligned.
762 stackCheck :: ClosureInfo
763 -> [MagicId] -- Live registers
764 -> Bool -- Node required to point after check?
768 stackCheck closure_info regs node_reqd code
769 = getFinalStackHW (\ aHw -> \ bHw -> -- Both virtual stack offsets
771 getVirtSps `thenFC` \ (vSpA, vSpB) ->
773 let a_headroom_reqd = aHw - vSpA -- Virtual offsets are positive integers
774 b_headroom_reqd = bHw - vSpB
777 absC (if (a_headroom_reqd == 0 && b_headroom_reqd == 0) then
780 CMacroStmt STK_CHK [mkIntCLit liveness_mask,
781 mkIntCLit a_headroom_reqd,
782 mkIntCLit b_headroom_reqd,
785 mkIntCLit (if returns_prim_type then 1 else 0),
786 mkIntCLit (if node_reqd then 1 else 0)]
788 -- The test is *inside* the absC, to avoid black holes!
793 all_regs = if node_reqd then node:regs else regs
794 liveness_mask = mkLiveRegsMask all_regs
796 returns_prim_type = closureReturnsUnboxedType closure_info
799 %************************************************************************
801 \subsubsubsection[update-and-BHs]{Update and black-hole wrappers}
803 %************************************************************************
807 blackHoleIt :: ClosureInfo -> Code -- Only called for thunks
808 blackHoleIt closure_info
809 = noBlackHolingFlag `thenFC` \ no_black_holing ->
811 if (blackHoleOnEntry no_black_holing closure_info)
813 absC (if closureSingleEntry(closure_info) then
814 CMacroStmt UPD_BH_SINGLE_ENTRY [CReg node]
816 CMacroStmt UPD_BH_UPDATABLE [CReg node])
817 -- Node always points to it; see stg-details
823 setupUpdate :: ClosureInfo -> Code -> Code -- Only called for thunks
824 -- Nota Bene: this function does not change Node (even if it's a CAF),
825 -- so that the cost centre in the original closure can still be
826 -- extracted by a subsequent ENTER_CC_TCL
828 setupUpdate closure_info code
829 = if (closureUpdReqd closure_info) then
830 link_caf_if_needed `thenFC` \ update_closure ->
831 pushUpdateFrame update_closure vector code
833 profCtrC SLIT("UPDF_OMITTED") [] `thenC`
836 link_caf_if_needed :: FCode CAddrMode -- Returns amode for closure to be updated
838 = if not (isStaticClosure closure_info) then
842 -- First we must allocate a black hole, and link the
843 -- CAF onto the CAF list
845 -- Alloc black hole specifying CC_HDR(Node) as the cost centre
846 -- Hack Warning: Using a CLitLit to get CAddrMode !
848 use_cc = CLitLit SLIT("CC_HDR(R1.p)") PtrRep
851 allocDynClosure (blackHoleClosureInfo closure_info) use_cc blame_cc []
852 `thenFC` \ heap_offset ->
853 getHpRelOffset heap_offset `thenFC` \ hp_rel ->
854 let amode = CAddr hp_rel
856 absC (CMacroStmt UPD_CAF [CReg node, amode])
860 closure_label = mkClosureLabel (closureId closure_info)
863 = case (closureType closure_info) of
864 Nothing -> CReg StdUpdRetVecReg
865 Just (spec_tycon, _, spec_datacons) ->
866 case (ctrlReturnConvAlg spec_tycon) of
867 UnvectoredReturn 1 ->
869 spec_data_con = head spec_datacons
870 only_tag = dataConTag spec_data_con
872 direct = case (dataReturnConvAlg spec_data_con) of
873 ReturnInRegs _ -> mkConUpdCodePtrVecLabel spec_tycon only_tag
874 ReturnInHeap -> mkStdUpdCodePtrVecLabel spec_tycon only_tag
876 vectored = mkStdUpdVecTblLabel spec_tycon
878 CUnVecLbl direct vectored
880 UnvectoredReturn _ -> CReg StdUpdRetVecReg
881 VectoredReturn _ -> CLbl (mkStdUpdVecTblLabel spec_tycon) DataPtrRep
884 %************************************************************************
886 \subsection[CgClosure-Description]{Profiling Closure Description.}
888 %************************************************************************
890 For "global" data constructors the description is simply occurrence
891 name of the data constructor itself (see \ref{CgConTbls-info-tables}).
893 Otherwise it is determind by @closureDescription@ from the let
897 closureDescription :: FAST_STRING -- Module
898 -> Id -- Id of closure binding
903 -- Not called for StgRhsCon which have global info tables built in
904 -- CgConTbls.lhs with a description generated from the data constructor
906 closureDescription mod_name name args body
907 = uppShow 0 (prettyToUn (
908 ppBesides [ppChar '<',
916 chooseDynCostCentres cc args fvs body
918 use_cc -- cost-centre we record in the object
919 = if currentOrSubsumedCosts cc
920 then CReg CurCostCentre
921 else mkCCostCentre cc
923 blame_cc -- cost-centre on whom we blame the allocation
924 = case (args, fvs, body) of
925 ([], [just1], StgApp (StgVarArg fun) [{-no args-}] _)
927 -> mkCCostCentre overheadCostCentre
929 -- if it's an utterly trivial RHS, then it must be
930 -- one introduced by boxHigherOrderArgs for profiling,
931 -- so we charge it to "OVERHEAD".