2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 % $Id: CgClosure.lhs,v 1.31 1999/05/18 15:03:47 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 ( adjustRealSp, mkTaggedVirtStkOffsets, freeStackSlots )
39 import CgUsages ( 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 )
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 ->
301 -- Figure out what is needed and what isn't
303 -- SDM: need everything for now in case the heap/stack check refers
305 slow_code_needed = True
306 --slowFunEntryCodeRequired name binder_info entry_conv
307 info_table_needed = True
308 --funInfoTableRequired name binder_info lf_info
310 -- Arg mapping for standard (slow) entry point; all args on stack,
312 (sp_all_args, arg_offsets, arg_tags)
313 = mkTaggedVirtStkOffsets vSp idPrimRep all_args
315 -- Arg mapping for the fast entry point; as many args as poss in
316 -- registers; the rest on the stack
317 -- arg_regs are the registers used for arg passing
318 -- stk_args are the args which are passed on the stack
320 -- Args passed on the stack are tagged, but the tags may not
321 -- actually be present (just gaps) if the function is called
322 -- by jumping directly to the fast entry point.
324 arg_regs = case entry_conv of
325 DirectEntry lbl arity regs -> regs
326 other -> panic "closureCodeBody:arg_regs"
328 num_arg_regs = length arg_regs
330 (reg_args, stk_args) = splitAt num_arg_regs all_args
332 (sp_stk_args, stk_offsets, stk_tags)
333 = mkTaggedVirtStkOffsets vSp idPrimRep stk_args
335 -- HWL; Note: empty list of live regs in slow entry code
336 -- Old version (reschedule combined with heap check);
337 -- see argSatisfactionCheck for new version
338 --slow_entry_code = forceHeapCheck [node] True slow_entry_code'
339 -- where node = UnusedReg PtrRep 1
340 --slow_entry_code = forceHeapCheck [] True slow_entry_code'
343 = profCtrC SLIT("TICK_ENT_FUN_STD") [] `thenC`
345 -- Bind args, and record expected position of stk ptrs
346 mapCs bindNewToStack arg_offsets `thenC`
347 setRealAndVirtualSp sp_all_args `thenC`
349 argSatisfactionCheck closure_info `thenC`
351 -- OK, so there are enough args. Now we need to stuff as
352 -- many of them in registers as the fast-entry code
353 -- expects. Note that the zipWith will give up when it hits
354 -- the end of arg_regs.
356 mapFCs getCAddrMode all_args `thenFC` \ stk_amodes ->
357 absC (mkAbstractCs (zipWith assign_to_reg arg_regs stk_amodes))
360 -- Now adjust real stack pointers
361 adjustRealSp sp_stk_args `thenC`
363 absC (CFallThrough (CLbl fast_label CodePtrRep))
365 assign_to_reg reg_id amode = CAssign (CReg reg_id) amode
368 -- Old version (reschedule combined with heap check);
369 -- see argSatisfactionCheck for new version
370 -- fast_entry_code = forceHeapCheck [] True fast_entry_code'
373 = profCtrC SLIT("TICK_ENT_FUN_DIRECT") [
374 mkIntCLit stg_arity -- total # of args
376 {- CLbl (mkRednCountsLabel name) PtrRep,
377 CString (_PK_ (showSDoc (ppr name))),
378 mkIntCLit stg_arity, -- total # of args
379 mkIntCLit sp_stk_args, -- # passed on stk
380 CString (_PK_ (map (showTypeCategory . idType) all_args)),
381 CString SLIT(""), CString SLIT("")
384 -- Nuked for now; see comment at end of file
385 -- CString (_PK_ (show_wrapper_name wrapper_maybe)),
386 -- CString (_PK_ (show_wrapper_arg_kinds wrapper_maybe))
390 -- Bind args to regs/stack as appropriate, and
391 -- record expected position of sps.
392 bindArgsToRegs reg_args arg_regs `thenC`
393 mapCs bindNewToStack stk_offsets `thenC`
394 setRealAndVirtualSp sp_stk_args `thenC`
396 -- free up the stack slots containing tags
397 freeStackSlots (map fst stk_tags) `thenC`
399 -- Enter the closures cc, if required
400 enterCostCentreCode closure_info cc IsFunction False `thenC`
403 funWrapper closure_info arg_regs stk_tags info_label (cgExpr body)
405 -- Make a labelled code-block for the slow and fast entry code
406 forkAbsC (if slow_code_needed then slow_entry_code else absC AbsCNop)
407 `thenFC` \ slow_abs_c ->
408 forkAbsC fast_entry_code `thenFC` \ fast_abs_c ->
409 moduleName `thenFC` \ mod_name ->
411 -- Now either construct the info table, or put the fast code in alone
412 -- (We never have slow code without an info table)
413 -- XXX probably need the info table and slow entry code in case of
414 -- a heap check failure.
416 if info_table_needed then
417 CClosureInfoAndCode closure_info slow_abs_c (Just fast_abs_c)
420 CCodeBlock fast_label fast_abs_c
423 stg_arity = length all_args
424 lf_info = closureLFInfo closure_info
426 cl_descr mod_name = closureDescription mod_name name
428 -- Manufacture labels
429 name = closureName closure_info
430 fast_label = mkFastEntryLabel name stg_arity
431 info_label = mkInfoTableLabel name
434 For lexically scoped profiling we have to load the cost centre from
435 the closure entered, if the costs are not supposed to be inherited.
436 This is done immediately on entering the fast entry point.
438 Load current cost centre from closure, if not inherited.
439 Node is guaranteed to point to it, if profiling and not inherited.
442 data IsThunk = IsThunk | IsFunction -- Bool-like, local
448 :: ClosureInfo -> CostCentreStack
450 -> Bool -- is_box: this closure is a special box introduced by SCCfinal
453 enterCostCentreCode closure_info ccs is_thunk is_box
454 = if not opt_SccProfilingOn then
457 ASSERT(not (noCCSAttached ccs))
459 if isSubsumedCCS ccs then
460 ASSERT(isToplevClosure closure_info)
461 ASSERT(is_thunk == IsFunction)
462 costCentresC SLIT("ENTER_CCS_FSUB") []
464 else if isCurrentCCS ccs then
465 if re_entrant && not is_box
466 then costCentresC SLIT("ENTER_CCS_FCL") [CReg node]
467 else costCentresC SLIT("ENTER_CCS_TCL") [CReg node]
469 else if isCafCCS ccs then
470 ASSERT(isToplevClosure closure_info)
471 ASSERT(is_thunk == IsThunk)
472 -- might be a PAP, in which case we want to subsume costs
474 then costCentresC SLIT("ENTER_CCS_FSUB") []
475 else costCentresC SLIT("ENTER_CCS_CAF") c_ccs
477 else panic "enterCostCentreCode"
480 c_ccs = [mkCCostCentreStack ccs]
481 re_entrant = closureReEntrant closure_info
484 %************************************************************************
486 \subsubsection[pre-closure-code-stuff]{Pre-closure-code code}
488 %************************************************************************
490 The argument-satisfaction check code is placed after binding
491 the arguments to their stack locations. Hence, the virtual stack
492 pointer is pointing after all the args, and virtual offset 1 means
493 the base of frame and hence most distant arg. Hence
494 virtual offset 0 is just beyond the most distant argument; the
495 relative offset of this word tells how many words of arguments
499 argSatisfactionCheck :: ClosureInfo -> Code
501 argSatisfactionCheck closure_info
503 = nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
506 emit_gran_macros = opt_GranMacros
510 -- absC (CMacroStmt GRAN_FETCH []) `thenC`
511 -- forceHeapCheck [] node_points (absC AbsCNop) `thenC`
514 then fetchAndReschedule [] node_points
515 else yield [] node_points
516 else absC AbsCNop) `thenC`
518 getSpRelOffset 0 `thenFC` \ (SpRel sp) ->
521 rel_arg = mkIntCLit off
525 absC (CMacroStmt ARGS_CHK [rel_arg]) -- node already points
527 absC (CMacroStmt ARGS_CHK_LOAD_NODE [rel_arg, set_Node_to_this])
529 -- We must tell the arg-satis macro whether Node is pointing to
530 -- the closure or not. If it isn't so pointing, then we give to
531 -- the macro the (static) address of the closure.
533 set_Node_to_this = CLbl (closureLabelFromCI closure_info) PtrRep
536 %************************************************************************
538 \subsubsection[closure-code-wrappers]{Wrappers around closure code}
540 %************************************************************************
543 thunkWrapper:: ClosureInfo -> CLabel -> Code -> Code
544 thunkWrapper closure_info label thunk_code
545 = -- Stack and heap overflow checks
546 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
549 emit_gran_macros = opt_GranMacros
551 -- HWL: insert macros for GrAnSim; 2 versions depending on liveness of node
552 -- (we prefer fetchAndReschedule-style context switches to yield ones)
555 then fetchAndReschedule [] node_points
556 else yield [] node_points
557 else absC AbsCNop) `thenC`
559 -- stack and/or heap checks
560 thunkChecks label node_points (
562 -- Overwrite with black hole if necessary
563 blackHoleIt closure_info node_points `thenC`
565 setupUpdate closure_info ( -- setupUpdate *encloses* the rest
567 -- Finally, do the business
571 funWrapper :: ClosureInfo -- Closure whose code body this is
572 -> [MagicId] -- List of argument registers (if any)
573 -> [(VirtualSpOffset,Int)] -- tagged stack slots
574 -> CLabel -- info table for heap check ret.
575 -> Code -- Body of function being compiled
577 funWrapper closure_info arg_regs stk_tags info_label fun_body
578 = -- Stack overflow check
579 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
581 emit_gran_macros = opt_GranMacros
585 then yield arg_regs node_points
586 else absC AbsCNop) `thenC`
588 -- heap and/or stack checks
589 fastEntryChecks arg_regs stk_tags info_label node_points (
591 -- Finally, do the business
597 %************************************************************************
599 \subsubsubsection[update-and-BHs]{Update and black-hole wrappers}
601 %************************************************************************
605 blackHoleIt :: ClosureInfo -> Bool -> Code -- Only called for closures with no args
607 blackHoleIt closure_info node_points
608 = if blackHoleOnEntry closure_info && node_points
610 absC (if closureSingleEntry(closure_info) then
611 CMacroStmt UPD_BH_SINGLE_ENTRY [CReg node]
613 CMacroStmt UPD_BH_UPDATABLE [CReg node])
619 setupUpdate :: ClosureInfo -> Code -> Code -- Only called for closures with no args
620 -- Nota Bene: this function does not change Node (even if it's a CAF),
621 -- so that the cost centre in the original closure can still be
622 -- extracted by a subsequent ENTER_CC_TCL
624 -- I've tidied up the code for this function, but it should still do the same as
625 -- it did before (modulo ticky stuff). KSW 1999-04.
626 setupUpdate closure_info code
627 = if closureReEntrant closure_info
631 case (closureUpdReqd closure_info, isStaticClosure closure_info) of
632 (False,False) -> profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
634 (False,True ) -> (if opt_DoTickyProfiling
636 -- blackhole the SE CAF
637 link_caf seCafBlackHoleClosureInfo `thenFC` \ _ -> nopC
640 profCtrC SLIT("TICK_UPD_CAF_BH_SINGLE_ENTRY") [CString cl_name] `thenC`
641 profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
643 (True ,False) -> pushUpdateFrame (CReg node) code
644 (True ,True ) -> -- blackhole the (updatable) CAF:
645 link_caf cafBlackHoleClosureInfo `thenFC` \ update_closure ->
646 profCtrC SLIT("TICK_UPD_CAF_BH_UPDATABLE") [CString cl_name] `thenC`
647 pushUpdateFrame update_closure code
649 cl_name :: FAST_STRING
650 cl_name = (occNameFS . nameOccName . closureName) closure_info
652 link_caf :: (ClosureInfo -> ClosureInfo) -- function yielding BH closure_info
653 -> FCode CAddrMode -- Returns amode for closure to be updated
655 = -- To update a CAF we must allocate a black hole, link the CAF onto the
656 -- CAF list, then update the CAF to point to the fresh black hole.
657 -- This function returns the address of the black hole, so it can be
658 -- updated with the new value when available.
660 -- Alloc black hole specifying CC_HDR(Node) as the cost centre
661 -- Hack Warning: Using a CLitLit to get CAddrMode !
663 use_cc = CLitLit SLIT("CCS_HDR(R1.p)") PtrRep
666 allocDynClosure (bhCI closure_info) use_cc blame_cc [] `thenFC` \ heap_offset ->
667 getHpRelOffset heap_offset `thenFC` \ hp_rel ->
668 let amode = CAddr hp_rel
670 absC (CMacroStmt UPD_CAF [CReg node, amode]) `thenC`
674 %************************************************************************
676 \subsection[CgClosure-Description]{Profiling Closure Description.}
678 %************************************************************************
680 For "global" data constructors the description is simply occurrence
681 name of the data constructor itself (see \ref{CgConTbls-info-tables}).
683 Otherwise it is determind by @closureDescription@ from the let
687 closureDescription :: Module -- Module
688 -> Name -- Id of closure binding
691 -- Not called for StgRhsCon which have global info tables built in
692 -- CgConTbls.lhs with a description generated from the data constructor
694 closureDescription mod_name name
704 chooseDynCostCentres ccs args fvs body
706 use_cc -- cost-centre we record in the object
707 = if currentOrSubsumedCCS ccs
708 then CReg CurCostCentre
709 else mkCCostCentreStack ccs
711 blame_cc -- cost-centre on whom we blame the allocation
712 = case (args, fvs, body) of
713 ([], _, StgApp fun [{-no args-}])
714 -> mkCCostCentreStack overheadCCS
717 -- if it's an utterly trivial RHS, then it must be
718 -- one introduced by boxHigherOrderArgs for profiling,
719 -- so we charge it to "OVERHEAD".
721 -- This looks like a HACK to me --SDM
728 ========================================================================
729 OLD CODE THAT EMITTED INFORMATON FOR QUANTITATIVE ANALYSIS
731 It's pretty wierd, so I've nuked it for now. SLPJ Nov 96
734 getWrapperArgTypeCategories
735 :: Type -- wrapper's type
736 -> StrictnessInfo bdee -- strictness info about its args
739 getWrapperArgTypeCategories _ NoStrictnessInfo = Nothing
740 getWrapperArgTypeCategories _ BottomGuaranteed
741 = trace "getWrapperArgTypeCategories:BottomGuaranteed!" Nothing -- wrong
742 getWrapperArgTypeCategories _ (StrictnessInfo [] _) = Nothing
744 getWrapperArgTypeCategories ty (StrictnessInfo arg_info _)
745 = Just (mkWrapperArgTypeCategories ty arg_info)
747 mkWrapperArgTypeCategories
748 :: Type -- wrapper's type
749 -> [Demand] -- info about its arguments
750 -> String -- a string saying lots about the args
752 mkWrapperArgTypeCategories wrapper_ty wrap_info
753 = case (splitFunTy_maybe wrapper_ty) of { Just (arg_tys,_) ->
754 map do_one (wrap_info `zip` (map showTypeCategory arg_tys)) }
756 -- ToDo: this needs FIXING UP (it was a hack anyway...)
757 do_one (WwPrim, _) = 'P'
758 do_one (WwEnum, _) = 'E'
759 do_one (WwStrict, arg_ty_char) = arg_ty_char
760 do_one (WwUnpack _ _ _, arg_ty_char)
761 = if arg_ty_char `elem` "CIJFDTS"
762 then toLower arg_ty_char
763 else if arg_ty_char == '+' then 't'
764 else trace ("mkWrapp..:funny char:"++[arg_ty_char]) '-'
765 do_one (other_wrap_info, _) = '-'