2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CgBindery]{Utility functions related to doing @CgBindings@}
9 StableLoc, VolatileLoc,
11 stableAmodeIdInfo, heapIdInfo, newTempAmodeAndIdInfo,
12 letNoEscapeIdInfo, idInfoToAmode,
19 bindNewToStack, rebindToStack,
20 bindNewToNode, bindNewToReg, bindArgsToRegs,
21 bindNewToTemp, bindNewPrimToAmode,
22 getArgAmode, getArgAmodes,
23 getCAddrModeAndInfo, getCAddrMode,
24 getCAddrModeIfVolatile, getVolatileRegs,
26 buildLivenessMask, buildContLivenessMask
29 #include "HsVersions.h"
34 import CgUsages ( getHpRelOffset, getSpRelOffset, getRealSp )
35 import CgStackery ( freeStackSlots )
36 import CLabel ( mkClosureLabel,
37 mkBitmapLabel, pprCLabel )
38 import ClosureInfo ( mkLFImported, mkLFArgument, LambdaFormInfo )
39 import BitSet ( mkBS, emptyBS )
40 import PrimRep ( isFollowableRep, getPrimRepSize )
41 import Id ( Id, idPrimRep, idType, isDataConWrapId )
42 import Type ( typePrimRep )
44 import VarSet ( varSetElems )
45 import Literal ( Literal )
46 import Maybes ( catMaybes, maybeToBool )
47 import Name ( isLocalName, NamedThing(..) )
49 import PprAbsC ( pprAmode )
51 import PrimRep ( PrimRep(..) )
52 import StgSyn ( StgArg, StgLiveVars, GenStgArg(..), isStgTypeArg )
53 import Unique ( Unique, Uniquable(..) )
54 import UniqSet ( elementOfUniqSet )
55 import Util ( zipWithEqual, sortLt )
60 %************************************************************************
62 \subsection[Bindery-datatypes]{Data types}
64 %************************************************************************
66 @(CgBinding a b)@ is a type of finite maps from a to b.
68 The assumption used to be that @lookupCgBind@ must get exactly one
69 match. This is {\em completely wrong} in the case of compiling
70 letrecs (where knot-tying is used). An initial binding is fed in (and
71 never evaluated); eventually, a correct binding is put into the
72 environment. So there can be two bindings for a given name.
75 type CgBindings = IdEnv CgIdInfo
78 = MkCgIdInfo Id -- Id that this is the info for
87 | RegLoc MagicId -- in one of the magic registers
88 -- (probably {Int,Float,Char,etc}Reg
90 | VirHpLoc VirtualHeapOffset -- Hp+offset (address of closure)
92 | VirNodeLoc VirtualHeapOffset -- Cts of offset indirect from Node
96 @StableLoc@ encodes where an Id can be found, used by
97 the @CgBindings@ environment in @CgBindery@.
102 | VirStkLoc VirtualSpOffset
104 | StableAmodeLoc CAddrMode
106 -- these are so StableLoc can be abstract:
108 maybeStkLoc (VirStkLoc offset) = Just offset
109 maybeStkLoc _ = Nothing
112 %************************************************************************
114 \subsection[Bindery-idInfo]{Manipulating IdInfo}
116 %************************************************************************
119 stableAmodeIdInfo i amode lf_info = MkCgIdInfo i NoVolatileLoc (StableAmodeLoc amode) lf_info
120 heapIdInfo i offset lf_info = MkCgIdInfo i (VirHpLoc offset) NoStableLoc lf_info
121 tempIdInfo i uniq lf_info = MkCgIdInfo i (TempVarLoc uniq) NoStableLoc lf_info
123 letNoEscapeIdInfo i sp lf_info
124 = MkCgIdInfo i NoVolatileLoc (StableAmodeLoc (CJoinPoint sp)) lf_info
126 newTempAmodeAndIdInfo :: Id -> LambdaFormInfo -> (CAddrMode, CgIdInfo)
128 newTempAmodeAndIdInfo name lf_info
129 = (temp_amode, temp_idinfo)
131 uniq = getUnique name
132 temp_amode = CTemp uniq (idPrimRep name)
133 temp_idinfo = tempIdInfo name uniq lf_info
135 idInfoToAmode :: PrimRep -> CgIdInfo -> FCode CAddrMode
136 idInfoToAmode kind (MkCgIdInfo _ vol stab _) = idInfoPiecesToAmode kind vol stab
138 idInfoPiecesToAmode :: PrimRep -> VolatileLoc -> StableLoc -> FCode CAddrMode
140 idInfoPiecesToAmode kind (TempVarLoc uniq) stable_loc = returnFC (CTemp uniq kind)
141 idInfoPiecesToAmode kind (RegLoc magic_id) stable_loc = returnFC (CReg magic_id)
143 idInfoPiecesToAmode kind NoVolatileLoc (LitLoc lit) = returnFC (CLit lit)
144 idInfoPiecesToAmode kind NoVolatileLoc (StableAmodeLoc amode) = returnFC amode
146 idInfoPiecesToAmode kind (VirNodeLoc nd_off) stable_loc
147 = returnFC (CVal (nodeRel nd_off) kind)
148 -- Virtual offsets from Node increase into the closures,
149 -- and so do Node-relative offsets (which we want in the CVal),
150 -- so there is no mucking about to do to the offset.
152 idInfoPiecesToAmode kind (VirHpLoc hp_off) stable_loc
153 = getHpRelOffset hp_off `thenFC` \ rel_hp ->
154 returnFC (CAddr rel_hp)
156 idInfoPiecesToAmode kind NoVolatileLoc (VirStkLoc i)
157 = getSpRelOffset i `thenFC` \ rel_sp ->
158 returnFC (CVal rel_sp kind)
161 idInfoPiecesToAmode kind NoVolatileLoc NoStableLoc = panic "idInfoPiecesToAmode: no loc"
165 %************************************************************************
167 \subsection[CgMonad-bindery]{Monad things for fiddling with @CgBindings@}
169 %************************************************************************
171 There are three basic routines, for adding (@addBindC@), modifying
172 (@modifyBindC@) and looking up (@lookupBindC@) bindings.
174 A @Id@ is bound to a @(VolatileLoc, StableLoc)@ triple.
175 The name should not already be bound. (nice ASSERT, eh?)
178 addBindC :: Id -> CgIdInfo -> Code
179 addBindC name stuff_to_bind info_down (MkCgState absC binds usage)
180 = MkCgState absC (extendVarEnv binds name stuff_to_bind) usage
182 addBindsC :: [(Id, CgIdInfo)] -> Code
183 addBindsC new_bindings info_down (MkCgState absC binds usage)
184 = MkCgState absC new_binds usage
186 new_binds = foldl (\ binds (name,info) -> extendVarEnv binds name info)
190 modifyBindC :: Id -> (CgIdInfo -> CgIdInfo) -> Code
191 modifyBindC name mangle_fn info_down (MkCgState absC binds usage)
192 = MkCgState absC (modifyVarEnv mangle_fn binds name) usage
194 lookupBindC :: Id -> FCode CgIdInfo
195 lookupBindC name info_down@(MkCgInfoDown _ static_binds srt ticky _)
196 state@(MkCgState absC local_binds usage)
199 val = case (lookupVarEnv local_binds name) of
200 Nothing -> try_static
204 case (lookupVarEnv static_binds name) of
207 -> cgPanic (text "lookupBindC: no info for" <+> ppr name) info_down state
209 cgPanic :: SDoc -> CgInfoDownwards -> CgState -> a
210 cgPanic doc info_down@(MkCgInfoDown _ static_binds srt ticky _)
211 state@(MkCgState absC local_binds usage)
214 ptext SLIT("static binds for:"),
215 vcat [ ppr i | (MkCgIdInfo i _ _ _) <- rngVarEnv static_binds ],
216 ptext SLIT("local binds for:"),
217 vcat [ ppr i | (MkCgIdInfo i _ _ _) <- rngVarEnv local_binds ],
218 ptext SLIT("SRT label") <+> pprCLabel srt
222 %************************************************************************
224 \subsection[Bindery-nuke-volatile]{Nuking volatile bindings}
226 %************************************************************************
228 We sometimes want to nuke all the volatile bindings; we must be sure
229 we don't leave any (NoVolatile, NoStable) binds around...
232 nukeVolatileBinds :: CgBindings -> CgBindings
233 nukeVolatileBinds binds
234 = mkVarEnv (foldr keep_if_stable [] (rngVarEnv binds))
236 keep_if_stable (MkCgIdInfo i _ NoStableLoc entry_info) acc = acc
237 keep_if_stable (MkCgIdInfo i _ stable_loc entry_info) acc
238 = (i, MkCgIdInfo i NoVolatileLoc stable_loc entry_info) : acc
242 %************************************************************************
244 \subsection[lookup-interface]{Interface functions to looking up bindings}
246 %************************************************************************
248 I {\em think} all looking-up is done through @getCAddrMode(s)@.
251 getCAddrModeAndInfo :: Id -> FCode (CAddrMode, LambdaFormInfo)
253 getCAddrModeAndInfo id
254 | not (isLocalName name) || isDataConWrapId id
255 -- Why the isDataConWrapId? Because CoreToStg changes a call to
256 -- a nullary constructor worker fn to a call to its wrapper,
257 -- which may not be defined until later
259 {- -- OLD: the unpack stuff isn't injected now Jan 2000
260 Why the "isWiredInName"?
261 Imagine you are compiling PrelBase.hs (a module that
262 supplies some of the wired-in values). What can
263 happen is that the compiler will inject calls to
264 (e.g.) GHCbase.unpackPS, where-ever it likes -- it
265 assumes those values are ubiquitously available.
266 The main point is: it may inject calls to them earlier
267 in GHCbase.hs than the actual definition...
269 = returnFC (global_amode, mkLFImported id)
271 | otherwise = -- *might* be a nested defn: in any case, it's something whose
272 -- definition we will know about...
273 lookupBindC id `thenFC` \ (MkCgIdInfo _ volatile_loc stable_loc lf_info) ->
274 idInfoPiecesToAmode kind volatile_loc stable_loc `thenFC` \ amode ->
275 returnFC (amode, lf_info)
278 global_amode = CLbl (mkClosureLabel name) kind
281 getCAddrMode :: Id -> FCode CAddrMode
283 = getCAddrModeAndInfo name `thenFC` \ (amode, _) ->
288 getCAddrModeIfVolatile :: Id -> FCode (Maybe CAddrMode)
289 getCAddrModeIfVolatile name
290 -- | toplevelishId name = returnFC Nothing
292 = lookupBindC name `thenFC` \ ~(MkCgIdInfo _ volatile_loc stable_loc lf_info) ->
294 NoStableLoc -> -- Aha! So it is volatile!
295 idInfoPiecesToAmode (idPrimRep name) volatile_loc NoStableLoc `thenFC` \ amode ->
296 returnFC (Just amode)
298 a_stable_loc -> returnFC Nothing
301 @getVolatileRegs@ gets a set of live variables, and returns a list of
302 all registers on which these variables depend. These are the regs
303 which must be saved and restored across any C calls. If a variable is
304 both in a volatile location (depending on a register) {\em and} a
305 stable one (notably, on the stack), we modify the current bindings to
306 forget the volatile one.
309 getVolatileRegs :: StgLiveVars -> FCode [MagicId]
312 = mapFCs snaffle_it (varSetElems vars) `thenFC` \ stuff ->
313 returnFC (catMaybes stuff)
316 = lookupBindC var `thenFC` \ (MkCgIdInfo _ volatile_loc stable_loc lf_info) ->
318 -- commoned-up code...
320 = if not (isVolatileReg reg) then
321 -- Potentially dies across C calls
322 -- For now, that's everything; we leave
323 -- it to the save-macros to decide which
324 -- regs *really* need to be saved.
328 NoStableLoc -> returnFC (Just reg) -- got one!
330 -- has both volatile & stable locations;
331 -- force it to rely on the stable location
332 modifyBindC var nuke_vol_bind `thenC`
336 RegLoc reg -> consider_reg reg
337 VirHpLoc _ -> consider_reg Hp
338 VirNodeLoc _ -> consider_reg node
339 non_reg_loc -> returnFC Nothing
341 nuke_vol_bind (MkCgIdInfo i _ stable_loc lf_info)
342 = MkCgIdInfo i NoVolatileLoc stable_loc lf_info
346 getArgAmodes :: [StgArg] -> FCode [CAddrMode]
347 getArgAmodes [] = returnFC []
348 getArgAmodes (atom:atoms)
352 = getArgAmode atom `thenFC` \ amode ->
353 getArgAmodes atoms `thenFC` \ amodes ->
354 returnFC ( amode : amodes )
356 getArgAmode :: StgArg -> FCode CAddrMode
358 getArgAmode (StgVarArg var) = getCAddrMode var -- The common case
359 getArgAmode (StgLitArg lit) = returnFC (CLit lit)
362 %************************************************************************
364 \subsection[binding-and-rebinding-interface]{Interface functions for binding and re-binding names}
366 %************************************************************************
369 bindNewToStack :: (Id, VirtualSpOffset) -> Code
370 bindNewToStack (name, offset)
373 info = MkCgIdInfo name NoVolatileLoc (VirStkLoc offset) mkLFArgument
375 bindNewToNode :: Id -> VirtualHeapOffset -> LambdaFormInfo -> Code
376 bindNewToNode name offset lf_info
379 info = MkCgIdInfo name (VirNodeLoc offset) NoStableLoc lf_info
381 -- Create a new temporary whose unique is that in the id,
382 -- bind the id to it, and return the addressing mode for the
384 bindNewToTemp :: Id -> FCode CAddrMode
386 = let (temp_amode, id_info) = newTempAmodeAndIdInfo name mkLFArgument
387 -- This is used only for things we don't know
388 -- anything about; values returned by a case statement,
391 addBindC name id_info `thenC`
394 bindNewToReg :: Id -> MagicId -> LambdaFormInfo -> Code
395 bindNewToReg name magic_id lf_info
398 info = MkCgIdInfo name (RegLoc magic_id) NoStableLoc lf_info
400 bindArgsToRegs :: [Id] -> [MagicId] -> Code
401 bindArgsToRegs args regs
402 = listCs (zipWithEqual "bindArgsToRegs" bind args regs)
404 arg `bind` reg = bindNewToReg arg reg mkLFArgument
407 @bindNewPrimToAmode@ works only for certain addressing modes. Making
408 this work for stack offsets is non-trivial (virt vs. real stack offset
412 bindNewPrimToAmode :: Id -> CAddrMode -> Code
413 bindNewPrimToAmode name (CReg reg)
414 = bindNewToReg name reg (panic "bindNewPrimToAmode")
416 bindNewPrimToAmode name (CTemp uniq kind)
417 = addBindC name (tempIdInfo name uniq (panic "bindNewPrimToAmode"))
420 bindNewPrimToAmode name amode
421 = pprPanic "bindNew...:" (pprAmode amode)
426 rebindToStack :: Id -> VirtualSpOffset -> Code
427 rebindToStack name offset
428 = modifyBindC name replace_stable_fn
430 replace_stable_fn (MkCgIdInfo i vol stab einfo)
431 = MkCgIdInfo i vol (VirStkLoc offset) einfo
434 %************************************************************************
436 \subsection[CgBindery-liveness]{Build a liveness mask for the current stack}
438 %************************************************************************
440 ToDo: remove the dependency on 32-bit words.
442 There are four kinds of things on the stack:
444 - pointer variables (bound in the environment)
445 - non-pointer variables (boudn in the environment)
446 - free slots (recorded in the stack free list)
447 - non-pointer data slots (recorded in the stack free list)
449 We build up a bitmap of non-pointer slots by looking down the
450 environment for all the non-pointer variables, and merging this with
451 the slots recorded in the stack free list.
453 There's a bit of a hack here to do with update frames: since nothing
454 is recorded in either the environment or the stack free list for an
455 update frame, the code below defaults to assuming the slots taken up
456 by an update frame contain pointers. Furthermore, update frames are
457 always in slots 0-2 at the bottom of the stack. The bitmap will
458 therefore end at slot 3, which is what we want (the update frame info
459 pointer has its own bitmap to describe the update frame).
463 :: Unique -- unique for for large bitmap label
464 -> VirtualSpOffset -- offset from which the bitmap should start
465 -> FCode Liveness -- mask for free/unlifted slots
467 buildLivenessMask uniq sp info_down
468 state@(MkCgState abs_c binds ((vsp, free, _, _), heap_usage))
469 = ASSERT(all (>=0) rel_slots)
470 livenessToAbsC uniq liveness_mask info_down state
472 -- find all unboxed stack-resident ids
475 (MkCgIdInfo id _ (VirStkLoc ofs) _) <- rngVarEnv binds,
476 let rep = idPrimRep id; size = getPrimRepSize rep,
477 not (isFollowableRep rep),
481 -- flatten this list into a list of unboxed stack slots
482 flatten_slots = sortLt (<)
483 (foldr (\(ofs,size) r -> [ofs-size+1 .. ofs] ++ r) []
486 -- merge in the free slots
487 all_slots = mergeSlots flatten_slots (map fst free) ++
488 if vsp < sp then [vsp+1 .. sp] else []
490 -- recalibrate the list to be sp-relative
491 rel_slots = reverse (map (sp-) all_slots)
494 liveness_mask = listToLivenessMask rel_slots
496 mergeSlots :: [Int] -> [Int] -> [Int]
497 mergeSlots cs [] = cs
498 mergeSlots [] ns = ns
499 mergeSlots (c:cs) (n:ns)
501 c : mergeSlots cs (n:ns)
503 n : mergeSlots (c:cs) ns
505 panic ("mergeSlots: equal slots: " ++ show (c:cs) ++ show (n:ns))
507 listToLivenessMask :: [Int] -> LivenessMask
508 listToLivenessMask [] = []
509 listToLivenessMask slots =
510 mkBS this : listToLivenessMask (map (\x -> x-32) rest)
511 where (this,rest) = span (<32) slots
513 livenessToAbsC :: Unique -> LivenessMask -> FCode Liveness
514 livenessToAbsC uniq [] = returnFC (LvSmall emptyBS)
515 livenessToAbsC uniq [one] = returnFC (LvSmall one)
516 livenessToAbsC uniq many =
517 absC (CBitmap lbl many) `thenC`
518 returnFC (LvLarge lbl)
519 where lbl = mkBitmapLabel uniq
522 In a continuation, we want a liveness mask that starts from just after
523 the return address, which is on the stack at realSp.
526 buildContLivenessMask
529 buildContLivenessMask uniq
530 = getRealSp `thenFC` \ realSp ->
531 buildLivenessMask uniq (realSp-1)
534 %************************************************************************
536 \subsection[CgMonad-deadslots]{Finding dead stack slots}
538 %************************************************************************
540 nukeDeadBindings does the following:
542 - Removes all bindings from the environment other than those
543 for variables in the argument to nukeDeadBindings.
544 - Collects any stack slots so freed, and returns them to the stack free
546 - Moves the virtual stack pointer to point to the topmost used
549 You can have multi-word slots on the stack (where a Double# used to
550 be, for instance); if dead, such a slot will be reported as *several*
551 offsets (one per word).
553 Probably *naughty* to look inside monad...
556 nukeDeadBindings :: StgLiveVars -- All the *live* variables
559 nukeDeadBindings live_vars info_down (MkCgState abs_c binds usage)
560 = freeStackSlots extra_free info_down (MkCgState abs_c (mkVarEnv bs') usage)
562 (dead_stk_slots, bs')
563 = dead_slots live_vars
565 [ (i, b) | b@(MkCgIdInfo i _ _ _) <- rngVarEnv binds ]
567 extra_free = sortLt (<) dead_stk_slots
570 Several boring auxiliary functions to do the dirty work.
573 dead_slots :: StgLiveVars
577 -> ([VirtualSpOffset], [(Id,CgIdInfo)])
579 -- dead_slots carries accumulating parameters for
580 -- filtered bindings, dead slots
581 dead_slots live_vars fbs ds []
582 = (ds, reverse fbs) -- Finished; rm the dups, if any
584 dead_slots live_vars fbs ds ((v,i):bs)
585 | v `elementOfUniqSet` live_vars
586 = dead_slots live_vars ((v,i):fbs) ds bs
587 -- Live, so don't record it in dead slots
588 -- Instead keep it in the filtered bindings
592 MkCgIdInfo _ _ stable_loc _
593 | is_stk_loc && size > 0 ->
594 dead_slots live_vars fbs ([offset-size+1 .. offset] ++ ds) bs
596 maybe_stk_loc = maybeStkLoc stable_loc
597 is_stk_loc = maybeToBool maybe_stk_loc
598 (Just offset) = maybe_stk_loc
600 _ -> dead_slots live_vars fbs ds bs
604 size = (getPrimRepSize . typePrimRep . idType) v