2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 % $Id: CgClosure.lhs,v 1.35 1999/10/13 16:39:15 simonmar 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 )
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 = profCtrC SLIT("TICK_CTR") [
376 CLbl ticky_ctr_label DataPtrRep,
377 mkCString (_PK_ (showSDocDebug (ppr name))),
378 mkIntCLit stg_arity, -- total # of args
379 mkIntCLit sp_stk_args, -- # passed on stk
380 mkCString (_PK_ (map (showTypeCategory . idType) all_args))
383 profCtrC SLIT("TICK_ENT_FUN_DIRECT") [
384 CLbl ticky_ctr_label DataPtrRep
387 -- Nuked for now; see comment at end of file
388 -- CString (_PK_ (show_wrapper_name wrapper_maybe)),
389 -- CString (_PK_ (show_wrapper_arg_kinds wrapper_maybe))
392 -- Bind args to regs/stack as appropriate, and
393 -- record expected position of sps.
394 bindArgsToRegs reg_args arg_regs `thenC`
395 mapCs bindNewToStack stk_offsets `thenC`
396 setRealAndVirtualSp sp_stk_args `thenC`
398 -- free up the stack slots containing tags
399 freeStackSlots (map fst stk_tags) `thenC`
401 -- Enter the closures cc, if required
402 enterCostCentreCode closure_info cc IsFunction False `thenC`
405 funWrapper closure_info arg_regs stk_tags info_label (cgExpr body)
408 setTickyCtrLabel ticky_ctr_label (
410 -- Make a labelled code-block for the slow and fast entry code
411 forkAbsC (if slow_code_needed then slow_entry_code else absC AbsCNop)
412 `thenFC` \ slow_abs_c ->
413 forkAbsC fast_entry_code `thenFC` \ fast_abs_c ->
414 moduleName `thenFC` \ mod_name ->
416 -- Now either construct the info table, or put the fast code in alone
417 -- (We never have slow code without an info table)
418 -- XXX probably need the info table and slow entry code in case of
419 -- a heap check failure.
421 if info_table_needed then
422 CClosureInfoAndCode closure_info slow_abs_c (Just fast_abs_c)
425 CCodeBlock fast_label fast_abs_c
429 ticky_ctr_label = mkRednCountsLabel name
431 stg_arity = length all_args
432 lf_info = closureLFInfo closure_info
434 cl_descr mod_name = closureDescription mod_name name
436 -- Manufacture labels
437 name = closureName closure_info
438 fast_label = mkFastEntryLabel name stg_arity
439 info_label = mkInfoTableLabel name
442 For lexically scoped profiling we have to load the cost centre from
443 the closure entered, if the costs are not supposed to be inherited.
444 This is done immediately on entering the fast entry point.
446 Load current cost centre from closure, if not inherited.
447 Node is guaranteed to point to it, if profiling and not inherited.
450 data IsThunk = IsThunk | IsFunction -- Bool-like, local
456 :: ClosureInfo -> CostCentreStack
458 -> Bool -- is_box: this closure is a special box introduced by SCCfinal
461 enterCostCentreCode closure_info ccs is_thunk is_box
462 = if not opt_SccProfilingOn then
465 ASSERT(not (noCCSAttached ccs))
467 if isSubsumedCCS ccs then
468 ASSERT(isToplevClosure closure_info)
469 ASSERT(is_thunk == IsFunction)
470 costCentresC SLIT("ENTER_CCS_FSUB") []
472 else if isCurrentCCS ccs then
473 if re_entrant && not is_box
474 then costCentresC SLIT("ENTER_CCS_FCL") [CReg node]
475 else costCentresC SLIT("ENTER_CCS_TCL") [CReg node]
477 else if isCafCCS ccs then
478 ASSERT(isToplevClosure closure_info)
479 ASSERT(is_thunk == IsThunk)
480 -- might be a PAP, in which case we want to subsume costs
482 then costCentresC SLIT("ENTER_CCS_FSUB") []
483 else costCentresC SLIT("ENTER_CCS_CAF") c_ccs
485 else panic "enterCostCentreCode"
488 c_ccs = [mkCCostCentreStack ccs]
489 re_entrant = closureReEntrant closure_info
492 %************************************************************************
494 \subsubsection[pre-closure-code-stuff]{Pre-closure-code code}
496 %************************************************************************
498 The argument-satisfaction check code is placed after binding
499 the arguments to their stack locations. Hence, the virtual stack
500 pointer is pointing after all the args, and virtual offset 1 means
501 the base of frame and hence most distant arg. Hence
502 virtual offset 0 is just beyond the most distant argument; the
503 relative offset of this word tells how many words of arguments
507 argSatisfactionCheck :: ClosureInfo -> Code
509 argSatisfactionCheck closure_info
511 = nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
514 emit_gran_macros = opt_GranMacros
518 -- absC (CMacroStmt GRAN_FETCH []) `thenC`
519 -- forceHeapCheck [] node_points (absC AbsCNop) `thenC`
522 then fetchAndReschedule [] node_points
523 else yield [] node_points
524 else absC AbsCNop) `thenC`
526 getSpRelOffset 0 `thenFC` \ (SpRel sp) ->
529 rel_arg = mkIntCLit off
533 absC (CMacroStmt ARGS_CHK [rel_arg]) -- node already points
535 absC (CMacroStmt ARGS_CHK_LOAD_NODE [rel_arg, set_Node_to_this])
537 -- We must tell the arg-satis macro whether Node is pointing to
538 -- the closure or not. If it isn't so pointing, then we give to
539 -- the macro the (static) address of the closure.
541 set_Node_to_this = CLbl (closureLabelFromCI closure_info) PtrRep
544 %************************************************************************
546 \subsubsection[closure-code-wrappers]{Wrappers around closure code}
548 %************************************************************************
551 thunkWrapper:: ClosureInfo -> CLabel -> Code -> Code
552 thunkWrapper closure_info lbl thunk_code
553 = -- Stack and heap overflow checks
554 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
557 emit_gran_macros = opt_GranMacros
559 -- HWL: insert macros for GrAnSim; 2 versions depending on liveness of node
560 -- (we prefer fetchAndReschedule-style context switches to yield ones)
563 then fetchAndReschedule [] node_points
564 else yield [] node_points
565 else absC AbsCNop) `thenC`
567 -- stack and/or heap checks
568 thunkChecks lbl node_points (
570 -- Overwrite with black hole if necessary
571 blackHoleIt closure_info node_points `thenC`
573 setupUpdate closure_info ( -- setupUpdate *encloses* the rest
575 -- Finally, do the business
579 funWrapper :: ClosureInfo -- Closure whose code body this is
580 -> [MagicId] -- List of argument registers (if any)
581 -> [(VirtualSpOffset,Int)] -- tagged stack slots
582 -> CLabel -- info table for heap check ret.
583 -> Code -- Body of function being compiled
585 funWrapper closure_info arg_regs stk_tags info_label fun_body
586 = -- Stack overflow check
587 nodeMustPointToIt (closureLFInfo closure_info) `thenFC` \ node_points ->
589 emit_gran_macros = opt_GranMacros
593 then yield arg_regs node_points
594 else absC AbsCNop) `thenC`
596 -- heap and/or stack checks
597 fastEntryChecks arg_regs stk_tags info_label node_points (
599 -- Finally, do the business
605 %************************************************************************
607 \subsubsubsection[update-and-BHs]{Update and black-hole wrappers}
609 %************************************************************************
613 blackHoleIt :: ClosureInfo -> Bool -> Code -- Only called for closures with no args
615 blackHoleIt closure_info node_points
616 = if blackHoleOnEntry closure_info && node_points
618 absC (if closureSingleEntry(closure_info) then
619 CMacroStmt UPD_BH_SINGLE_ENTRY [CReg node]
621 CMacroStmt UPD_BH_UPDATABLE [CReg node])
627 setupUpdate :: ClosureInfo -> Code -> Code -- Only called for closures with no args
628 -- Nota Bene: this function does not change Node (even if it's a CAF),
629 -- so that the cost centre in the original closure can still be
630 -- extracted by a subsequent ENTER_CC_TCL
632 -- I've tidied up the code for this function, but it should still do the same as
633 -- it did before (modulo ticky stuff). KSW 1999-04.
634 setupUpdate closure_info code
635 = if closureReEntrant closure_info
639 case (closureUpdReqd closure_info, isStaticClosure closure_info) of
640 (False,False) -> profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
642 (False,True ) -> (if opt_DoTickyProfiling
644 -- blackhole the SE CAF
645 link_caf seCafBlackHoleClosureInfo `thenFC` \ _ -> nopC
648 profCtrC SLIT("TICK_UPD_CAF_BH_SINGLE_ENTRY") [mkCString cl_name] `thenC`
649 profCtrC SLIT("TICK_UPDF_OMITTED") [] `thenC`
651 (True ,False) -> pushUpdateFrame (CReg node) code
652 (True ,True ) -> -- blackhole the (updatable) CAF:
653 link_caf cafBlackHoleClosureInfo `thenFC` \ update_closure ->
654 profCtrC SLIT("TICK_UPD_CAF_BH_UPDATABLE") [mkCString cl_name] `thenC`
655 pushUpdateFrame update_closure code
657 cl_name :: FAST_STRING
658 cl_name = (occNameFS . nameOccName . closureName) closure_info
660 link_caf :: (ClosureInfo -> ClosureInfo) -- function yielding BH closure_info
661 -> FCode CAddrMode -- Returns amode for closure to be updated
663 = -- To update a CAF we must allocate a black hole, link the CAF onto the
664 -- CAF list, then update the CAF to point to the fresh black hole.
665 -- This function returns the address of the black hole, so it can be
666 -- updated with the new value when available.
668 -- Alloc black hole specifying CC_HDR(Node) as the cost centre
669 -- Hack Warning: Using a CLitLit to get CAddrMode !
671 use_cc = CLitLit SLIT("CCS_HDR(R1.p)") PtrRep
674 allocDynClosure (bhCI closure_info) use_cc blame_cc [] `thenFC` \ heap_offset ->
675 getHpRelOffset heap_offset `thenFC` \ hp_rel ->
676 let amode = CAddr hp_rel
678 absC (CMacroStmt UPD_CAF [CReg node, amode]) `thenC`
682 %************************************************************************
684 \subsection[CgClosure-Description]{Profiling Closure Description.}
686 %************************************************************************
688 For "global" data constructors the description is simply occurrence
689 name of the data constructor itself (see \ref{CgConTbls-info-tables}).
691 Otherwise it is determind by @closureDescription@ from the let
695 closureDescription :: Module -- Module
696 -> Name -- Id of closure binding
699 -- Not called for StgRhsCon which have global info tables built in
700 -- CgConTbls.lhs with a description generated from the data constructor
702 closureDescription mod_name name
712 chooseDynCostCentres ccs args fvs body
714 use_cc -- cost-centre we record in the object
715 = if currentOrSubsumedCCS ccs
716 then CReg CurCostCentre
717 else mkCCostCentreStack ccs
719 blame_cc -- cost-centre on whom we blame the allocation
720 = case (args, fvs, body) of
721 ([], _, StgApp fun [{-no args-}])
722 -> mkCCostCentreStack overheadCCS
725 -- if it's an utterly trivial RHS, then it must be
726 -- one introduced by boxHigherOrderArgs for profiling,
727 -- so we charge it to "OVERHEAD".
729 -- This looks like a HACK to me --SDM
736 ========================================================================
737 OLD CODE THAT EMITTED INFORMATON FOR QUANTITATIVE ANALYSIS
739 It's pretty wierd, so I've nuked it for now. SLPJ Nov 96
742 getWrapperArgTypeCategories
743 :: Type -- wrapper's type
744 -> StrictnessInfo bdee -- strictness info about its args
747 getWrapperArgTypeCategories _ NoStrictnessInfo = Nothing
748 getWrapperArgTypeCategories _ BottomGuaranteed
749 = trace "getWrapperArgTypeCategories:BottomGuaranteed!" Nothing -- wrong
750 getWrapperArgTypeCategories _ (StrictnessInfo [] _) = Nothing
752 getWrapperArgTypeCategories ty (StrictnessInfo arg_info _)
753 = Just (mkWrapperArgTypeCategories ty arg_info)
755 mkWrapperArgTypeCategories
756 :: Type -- wrapper's type
757 -> [Demand] -- info about its arguments
758 -> String -- a string saying lots about the args
760 mkWrapperArgTypeCategories wrapper_ty wrap_info
761 = case (splitFunTy_maybe wrapper_ty) of { Just (arg_tys,_) ->
762 map do_one (wrap_info `zip` (map showTypeCategory arg_tys)) }
764 -- ToDo: this needs FIXING UP (it was a hack anyway...)
765 do_one (WwPrim, _) = 'P'
766 do_one (WwEnum, _) = 'E'
767 do_one (WwStrict, arg_ty_char) = arg_ty_char
768 do_one (WwUnpack _ _ _, arg_ty_char)
769 = if arg_ty_char `elem` "CIJFDTS"
770 then toLower arg_ty_char
771 else if arg_ty_char == '+' then 't'
772 else trace ("mkWrapp..:funny char:"++[arg_ty_char]) '-'
773 do_one (other_wrap_info, _) = '-'