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 )
40 import PrimRep ( isFollowableRep, getPrimRepSize )
41 import Id ( Id, idPrimRep, idType )
42 import Type ( typePrimRep )
44 import VarSet ( varSetElems )
45 import Literal ( Literal )
46 import Maybes ( catMaybes, maybeToBool, seqMaybe )
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 = do
181 setBinds $ extendVarEnv binds name stuff_to_bind
183 addBindsC :: [(Id, CgIdInfo)] -> Code
184 addBindsC new_bindings = do
186 let new_binds = foldl (\ binds (name,info) -> extendVarEnv binds name info)
191 modifyBindC :: Id -> (CgIdInfo -> CgIdInfo) -> Code
192 modifyBindC name mangle_fn = do
194 setBinds $ modifyVarEnv mangle_fn binds name
196 lookupBindC :: Id -> FCode CgIdInfo
197 lookupBindC id = do maybe_info <- lookupBindC_maybe id
199 Just info -> return info
200 Nothing -> cgLookupPanic id
202 lookupBindC_maybe :: Id -> FCode (Maybe CgIdInfo)
204 = do static_binds <- getStaticBinds
205 local_binds <- getBinds
206 return (lookupVarEnv local_binds id
208 lookupVarEnv static_binds id)
210 cgLookupPanic :: Id -> FCode a
212 = do static_binds <- getStaticBinds
213 local_binds <- getBinds
217 ptext SLIT("static binds for:"),
218 vcat [ ppr i | (MkCgIdInfo i _ _ _) <- rngVarEnv static_binds ],
219 ptext SLIT("local binds for:"),
220 vcat [ ppr i | (MkCgIdInfo i _ _ _) <- rngVarEnv local_binds ],
221 ptext SLIT("SRT label") <+> pprCLabel srt
225 %************************************************************************
227 \subsection[Bindery-nuke-volatile]{Nuking volatile bindings}
229 %************************************************************************
231 We sometimes want to nuke all the volatile bindings; we must be sure
232 we don't leave any (NoVolatile, NoStable) binds around...
235 nukeVolatileBinds :: CgBindings -> CgBindings
236 nukeVolatileBinds binds
237 = mkVarEnv (foldr keep_if_stable [] (rngVarEnv binds))
239 keep_if_stable (MkCgIdInfo i _ NoStableLoc entry_info) acc = acc
240 keep_if_stable (MkCgIdInfo i _ stable_loc entry_info) acc
241 = (i, MkCgIdInfo i NoVolatileLoc stable_loc entry_info) : acc
245 %************************************************************************
247 \subsection[lookup-interface]{Interface functions to looking up bindings}
249 %************************************************************************
251 I {\em think} all looking-up is done through @getCAddrMode(s)@.
254 getCAddrModeAndInfo :: Id -> FCode (Id, CAddrMode, LambdaFormInfo)
256 getCAddrModeAndInfo id
258 maybe_cg_id_info <- lookupBindC_maybe id
259 case maybe_cg_id_info of
261 -- Nothing => not in the environment, so should be imported
262 Nothing | isLocalName name -> cgLookupPanic id
263 | otherwise -> returnFC (id, global_amode, mkLFImported id)
265 Just (MkCgIdInfo id' volatile_loc stable_loc lf_info)
266 -> do amode <- idInfoPiecesToAmode kind volatile_loc stable_loc
267 return (id', amode, lf_info)
270 global_amode = CLbl (mkClosureLabel name) kind
273 getCAddrMode :: Id -> FCode CAddrMode
274 getCAddrMode name = do
275 (_, amode, _) <- getCAddrModeAndInfo name
280 getCAddrModeIfVolatile :: Id -> FCode (Maybe CAddrMode)
281 getCAddrModeIfVolatile name
282 -- | toplevelishId name = returnFC Nothing
285 (MkCgIdInfo _ volatile_loc stable_loc lf_info) <- lookupBindC name
287 NoStableLoc -> do -- Aha! So it is volatile!
288 amode <- idInfoPiecesToAmode (idPrimRep name) volatile_loc NoStableLoc
290 a_stable_loc -> return Nothing
293 @getVolatileRegs@ gets a set of live variables, and returns a list of
294 all registers on which these variables depend. These are the regs
295 which must be saved and restored across any C calls. If a variable is
296 both in a volatile location (depending on a register) {\em and} a
297 stable one (notably, on the stack), we modify the current bindings to
298 forget the volatile one.
301 getVolatileRegs :: StgLiveVars -> FCode [MagicId]
303 getVolatileRegs vars = do
304 stuff <- mapFCs snaffle_it (varSetElems vars)
305 returnFC $ catMaybes stuff
308 (MkCgIdInfo _ volatile_loc stable_loc lf_info) <- lookupBindC var
310 -- commoned-up code...
312 if not (isVolatileReg reg) then
313 -- Potentially dies across C calls
314 -- For now, that's everything; we leave
315 -- it to the save-macros to decide which
316 -- regs *really* need to be saved.
320 NoStableLoc -> returnFC (Just reg) -- got one!
321 is_a_stable_loc -> do
322 -- has both volatile & stable locations;
323 -- force it to rely on the stable location
324 modifyBindC var nuke_vol_bind
328 RegLoc reg -> consider_reg reg
329 VirHpLoc _ -> consider_reg Hp
330 VirNodeLoc _ -> consider_reg node
331 non_reg_loc -> returnFC Nothing
333 nuke_vol_bind (MkCgIdInfo i _ stable_loc lf_info)
334 = MkCgIdInfo i NoVolatileLoc stable_loc lf_info
338 getArgAmodes :: [StgArg] -> FCode [CAddrMode]
339 getArgAmodes [] = returnFC []
340 getArgAmodes (atom:atoms)
344 amode <- getArgAmode atom
345 amodes <- getArgAmodes atoms
346 return ( amode : amodes )
348 getArgAmode :: StgArg -> FCode CAddrMode
350 getArgAmode (StgVarArg var) = getCAddrMode var -- The common case
351 getArgAmode (StgLitArg lit) = returnFC (CLit lit)
354 %************************************************************************
356 \subsection[binding-and-rebinding-interface]{Interface functions for binding and re-binding names}
358 %************************************************************************
361 bindNewToStack :: (Id, VirtualSpOffset) -> Code
362 bindNewToStack (name, offset)
365 info = MkCgIdInfo name NoVolatileLoc (VirStkLoc offset) mkLFArgument
367 bindNewToNode :: Id -> VirtualHeapOffset -> LambdaFormInfo -> Code
368 bindNewToNode name offset lf_info
371 info = MkCgIdInfo name (VirNodeLoc offset) NoStableLoc lf_info
373 -- Create a new temporary whose unique is that in the id,
374 -- bind the id to it, and return the addressing mode for the
376 bindNewToTemp :: Id -> FCode CAddrMode
378 = let (temp_amode, id_info) = newTempAmodeAndIdInfo name mkLFArgument
379 -- This is used only for things we don't know
380 -- anything about; values returned by a case statement,
383 addBindC name id_info
386 bindNewToReg :: Id -> MagicId -> LambdaFormInfo -> Code
387 bindNewToReg name magic_id lf_info
390 info = MkCgIdInfo name (RegLoc magic_id) NoStableLoc lf_info
392 bindArgsToRegs :: [Id] -> [MagicId] -> Code
393 bindArgsToRegs args regs
394 = listCs (zipWithEqual "bindArgsToRegs" bind args regs)
396 arg `bind` reg = bindNewToReg arg reg mkLFArgument
399 @bindNewPrimToAmode@ works only for certain addressing modes. Making
400 this work for stack offsets is non-trivial (virt vs. real stack offset
404 bindNewPrimToAmode :: Id -> CAddrMode -> Code
405 bindNewPrimToAmode name (CReg reg)
406 = bindNewToReg name reg (panic "bindNewPrimToAmode")
408 bindNewPrimToAmode name (CTemp uniq kind)
409 = addBindC name (tempIdInfo name uniq (panic "bindNewPrimToAmode"))
412 bindNewPrimToAmode name amode
413 = pprPanic "bindNew...:" (pprAmode amode)
418 rebindToStack :: Id -> VirtualSpOffset -> Code
419 rebindToStack name offset
420 = modifyBindC name replace_stable_fn
422 replace_stable_fn (MkCgIdInfo i vol stab einfo)
423 = MkCgIdInfo i vol (VirStkLoc offset) einfo
426 %************************************************************************
428 \subsection[CgBindery-liveness]{Build a liveness mask for the current stack}
430 %************************************************************************
432 There are four kinds of things on the stack:
434 - pointer variables (bound in the environment)
435 - non-pointer variables (boudn in the environment)
436 - free slots (recorded in the stack free list)
437 - non-pointer data slots (recorded in the stack free list)
439 We build up a bitmap of non-pointer slots by looking down the
440 environment for all the non-pointer variables, and merging this with
441 the slots recorded in the stack free list.
443 There's a bit of a hack here to do with update frames: since nothing
444 is recorded in either the environment or the stack free list for an
445 update frame, the code below defaults to assuming the slots taken up
446 by an update frame contain pointers. Furthermore, update frames are
447 always in slots 0-2 at the bottom of the stack. The bitmap will
448 therefore end at slot 3, which is what we want (the update frame info
449 pointer has its own bitmap to describe the update frame).
453 :: Unique -- unique for for large bitmap label
454 -> VirtualSpOffset -- offset from which the bitmap should start
455 -> FCode Liveness -- mask for free/unlifted slots
457 buildLivenessMask uniq sp = do
459 -- find all unboxed stack-resident ids
461 ((vsp, free, _, _), heap_usage) <- getUsage
465 (MkCgIdInfo id _ (VirStkLoc ofs) _) <- rngVarEnv binds,
466 let rep = idPrimRep id; size = getPrimRepSize rep,
467 not (isFollowableRep rep),
471 -- flatten this list into a list of unboxed stack slots
472 let flatten_slots = sortLt (<)
473 (foldr (\(ofs,size) r -> [ofs-size+1 .. ofs] ++ r) []
476 -- merge in the free slots
477 let all_slots = mergeSlots flatten_slots (map fst free) ++
478 if vsp < sp then [vsp+1 .. sp] else []
480 -- recalibrate the list to be sp-relative
481 let rel_slots = reverse (map (sp-) all_slots)
485 = ASSERT(all (>=0) rel_slots
486 && rel_slots == sortLt (<) rel_slots)
487 (listToLivenessMask rel_slots)
489 livenessToAbsC uniq liveness_mask
491 mergeSlots :: [Int] -> [Int] -> [Int]
492 mergeSlots cs [] = cs
493 mergeSlots [] ns = ns
494 mergeSlots (c:cs) (n:ns)
496 c : mergeSlots cs (n:ns)
498 n : mergeSlots (c:cs) ns
500 panic ("mergeSlots: equal slots: " ++ show (c:cs) ++ show (n:ns))
502 listToLivenessMask :: [Int] -> LivenessMask
503 listToLivenessMask [] = []
504 listToLivenessMask slots =
505 mkBS this : listToLivenessMask (map (\x -> x-32) rest)
506 where (this,rest) = span (<32) slots
508 livenessToAbsC :: Unique -> LivenessMask -> FCode Liveness
509 livenessToAbsC uniq mask =
510 absC (CBitmap lbl mask) `thenC`
511 returnFC (Liveness lbl mask)
512 where lbl = mkBitmapLabel uniq
515 In a continuation, we want a liveness mask that starts from just after
516 the return address, which is on the stack at realSp.
519 buildContLivenessMask
522 buildContLivenessMask uniq = do
524 buildLivenessMask uniq (realSp-1)
527 %************************************************************************
529 \subsection[CgMonad-deadslots]{Finding dead stack slots}
531 %************************************************************************
533 nukeDeadBindings does the following:
535 - Removes all bindings from the environment other than those
536 for variables in the argument to nukeDeadBindings.
537 - Collects any stack slots so freed, and returns them to the stack free
539 - Moves the virtual stack pointer to point to the topmost used
542 You can have multi-word slots on the stack (where a Double# used to
543 be, for instance); if dead, such a slot will be reported as *several*
544 offsets (one per word).
546 Probably *naughty* to look inside monad...
549 nukeDeadBindings :: StgLiveVars -- All the *live* variables
551 nukeDeadBindings live_vars = do
553 let (dead_stk_slots, bs') =
556 [ (i, b) | b@(MkCgIdInfo i _ _ _) <- rngVarEnv binds ]
557 setBinds $ mkVarEnv bs'
558 freeStackSlots dead_stk_slots
561 Several boring auxiliary functions to do the dirty work.
564 dead_slots :: StgLiveVars
568 -> ([VirtualSpOffset], [(Id,CgIdInfo)])
570 -- dead_slots carries accumulating parameters for
571 -- filtered bindings, dead slots
572 dead_slots live_vars fbs ds []
573 = (ds, reverse fbs) -- Finished; rm the dups, if any
575 dead_slots live_vars fbs ds ((v,i):bs)
576 | v `elementOfUniqSet` live_vars
577 = dead_slots live_vars ((v,i):fbs) ds bs
578 -- Live, so don't record it in dead slots
579 -- Instead keep it in the filtered bindings
583 MkCgIdInfo _ _ stable_loc _
584 | is_stk_loc && size > 0 ->
585 dead_slots live_vars fbs ([offset-size+1 .. offset] ++ ds) bs
587 maybe_stk_loc = maybeStkLoc stable_loc
588 is_stk_loc = maybeToBool maybe_stk_loc
589 (Just offset) = maybe_stk_loc
591 _ -> dead_slots live_vars fbs ds bs
595 size = (getPrimRepSize . typePrimRep . idType) v