1 {-# OPTIONS_GHC -XNoMonoLocalBinds #-}
2 -- Norman likes local bindings
3 -- If this module lives on I'd like to get rid of this flag in due course
5 module CmmBuildInfoTables
6 ( CAFSet, CAFEnv, CmmTopForInfoTables(..), cafAnal, localCAFInfo, mkTopCAFInfo
7 , setInfoTableSRT, setInfoTableStackMap
8 , TopSRT, emptySRT, srtToData
10 , finishInfoTables, lowerSafeForeignCalls
11 , cafTransfers, liveSlotTransfers
12 , extendEnvWithSafeForeignCalls, extendEnvsForSafeForeignCalls )
15 #include "HsVersions.h"
19 import qualified Prelude as P
26 import Cmm hiding (blockId)
39 import MkZipCfgCmm hiding (CmmAGraph, CmmBlock, CmmTopZ, CmmZ, CmmGraph)
49 import ZipCfg hiding (zip, unzip, last)
50 import qualified ZipCfg as G
55 import qualified Data.Map as Map
56 import qualified FiniteMap as Map
58 ----------------------------------------------------------------
59 -- Building InfoTables
62 -----------------------------------------------------------------------
65 -- Given a block ID, we return a representation of the layout of the stack,
66 -- as suspended before entering that block.
67 -- (For a return site to a function call, the layout does not include the
68 -- parameter passing area (or the "return address" on the stack)).
69 -- If the element is `Nothing`, then it represents a word of the stack that
70 -- does not contain a live pointer.
71 -- If the element is `Just` a register, then it represents a live spill slot
72 -- for a pointer; we assume that a pointer is the size of a word.
73 -- The head of the list represents the young end of the stack where the infotable
74 -- pointer for the block `Bid` is stored.
75 -- The infotable pointer itself is not included in the list.
76 -- Call areas are also excluded from the list: besides the stuff in the update
77 -- frame (and the return infotable), call areas should never be live across
80 -- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
81 -- represents a word. Consequently, we have to be careful when we see a live slot
82 -- on the stack: if we have packed multiple sub-word values into a word,
83 -- we have to make sure that we only mark the entire word as a non-pointer.
85 -- Also, don't forget to stop at the old end of the stack (oldByte),
86 -- which may differ depending on whether there is an update frame.
89 = ( Int -- Offset from oldest byte of Old area
90 , LocalReg -- The register
91 , Int) -- Width of the register
93 live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
94 live_ptrs oldByte slotEnv areaMap bid =
95 -- pprTrace "live_ptrs for" (ppr bid <+> text (show oldByte ++ "-" ++ show youngByte) <+>
97 -- pprTrace ("stack layout for " ++ show bid ++ ": ") (ppr res) $ res
99 where res = reverse $ slotsToList youngByte liveSlots []
101 slotsToList :: Int -> [RegSlotInfo] -> [Maybe LocalReg] -> [Maybe LocalReg]
102 -- n starts at youngByte and is decremented down to oldByte
103 -- Returns a list, one element per word, with
104 -- (Just r) meaning 'pointer register r is saved here',
105 -- Nothing meaning 'non-pointer or empty'
107 slotsToList n [] results | n == oldByte = results -- at old end of stack frame
109 slotsToList n (s : _) _ | n == oldByte =
110 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
111 ppr n <+> ppr liveSlots <+> ppr youngByte)
113 slotsToList n _ _ | n < oldByte =
114 panic "stack slots not allocated on word boundaries?"
116 slotsToList n l@((n', r, w) : rst) results =
117 if n == (n' + w) then -- slot's young byte is at n
118 ASSERT (not (isPtr r) ||
119 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
120 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
121 (stack_rep : results)
122 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
124 where next = n - wORD_SIZE
125 stack_rep = if isPtr r then Just r else Nothing
127 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
129 non_ptr_younger_than next (n', r, w) =
131 ASSERT (not (isPtr r))
133 isPtr = isGcPtrType . localRegType
135 liveSlots :: [RegSlotInfo]
136 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
137 (Map.foldRightWithKey (\_ -> flip $ foldl add_slot) [] slots)
139 add_slot :: [RegSlotInfo] -> SubArea -> [RegSlotInfo]
140 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
141 if off == w && widthInBytes (typeWidth ty) == w then
142 (expectJust "add_slot" (Map.lookup a areaMap), r, w) : rst
143 else panic "live_ptrs: only part of a variable live at a proc point"
144 add_slot rst (CallArea Old, _, _) =
145 rst -- the update frame (or return infotable) should be live
146 -- would be nice to check that only that part of the callarea is live...
147 add_slot rst ((CallArea _), _, _) =
149 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
150 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
151 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
152 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
153 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
154 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
155 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
157 slots :: SubAreaSet -- The SubAreaSet for 'bid'
158 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
159 youngByte = expectJust "live_ptrs bid_pos" $ Map.lookup (CallArea (Young bid)) areaMap
161 -- Construct the stack maps for the given procedure.
162 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
163 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
164 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
165 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
166 setInfoTableStackMap slotEnv areaMap
167 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
168 case blockSetToList procpoints of
169 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
170 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
171 -- until we stop splitting the graphs at procpoints in the native path
172 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
176 -----------------------------------------------------------------------
179 -- WE NEED AN EXAMPLE HERE.
180 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
181 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
182 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
183 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
184 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
185 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
188 -----------------------------------------------------------------------
189 -- Finding the CAFs used by a procedure
191 type CAFSet = Map CLabel ()
192 type CAFEnv = BlockEnv CAFSet
194 -- First, an analysis to find live CAFs.
195 cafLattice :: DataflowLattice CAFSet
196 cafLattice = DataflowLattice "live cafs" Map.empty add False
197 where add new old = if Map.size new' > Map.size old
200 where new' = new `Map.union` old
202 cafTransfers :: BackwardTransfers Middle Last CAFSet
203 cafTransfers = BackwardTransfers first middle last
204 where first _ live = live
205 middle m live = foldExpDeepMiddle addCaf m live
206 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
207 addCaf e set = case e of
208 CmmLit (CmmLabel c) -> add c set
209 CmmLit (CmmLabelOff c _) -> add c set
210 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
212 add l s = if hasCAF l then Map.insert (cvtToClosureLbl l) () s else s
214 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
215 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
216 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
217 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
218 cafTransfers (fact_bot cafLattice) g
220 -----------------------------------------------------------------------
223 -- Description of the SRT for a given module.
224 -- Note that this SRT may grow as we greedily add new CAFs to it.
225 data TopSRT = TopSRT { lbl :: CLabel
226 , next_elt :: Int -- the next entry in the table
227 , rev_elts :: [CLabel]
228 , elt_map :: Map CLabel Int }
229 -- map: CLabel -> its last entry in the table
230 instance Outputable TopSRT where
231 ppr (TopSRT lbl next elts eltmap) =
232 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
234 emptySRT :: MonadUnique m => m TopSRT
236 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
237 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = Map.empty }
239 cafMember :: TopSRT -> CLabel -> Bool
240 cafMember srt lbl = Map.member lbl (elt_map srt)
242 cafOffset :: TopSRT -> CLabel -> Maybe Int
243 cafOffset srt lbl = Map.lookup lbl (elt_map srt)
245 addCAF :: CLabel -> TopSRT -> TopSRT
247 srt { next_elt = last + 1
248 , rev_elts = caf : rev_elts srt
249 , elt_map = Map.insert caf last (elt_map srt) }
250 where last = next_elt srt
252 srtToData :: TopSRT -> CmmZ
253 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
254 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
256 -- Once we have found the CAFs, we need to do two things:
257 -- 1. Build a table of all the CAFs used in the procedure.
258 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
260 -- When building the local view of the SRT, we first make sure that all the CAFs are
261 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
262 -- we make sure they're all close enough to the bottom of the table that the
263 -- bitmap will be able to cover all of them.
264 buildSRTs :: TopSRT -> Map CLabel CAFSet -> CAFSet ->
265 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
266 buildSRTs topSRT topCAFMap cafs =
267 do let liftCAF lbl () z = -- get CAFs for functions without static closures
268 case Map.lookup lbl topCAFMap of Just cafs -> z `Map.union` cafs
269 Nothing -> Map.insert lbl () z
270 -- For each label referring to a function f without a static closure,
271 -- replace it with the CAFs that are reachable from f.
272 sub_srt topSRT localCafs =
273 let cafs = Map.keys (Map.foldRightWithKey liftCAF Map.empty localCafs)
275 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
276 return (topSRT, localSRTs)
277 in if length cafs > maxBmpSize then
278 mkSRT (foldl add_if_missing topSRT cafs)
279 else -- make sure all the cafs are near the bottom of the srt
280 mkSRT (add_if_too_far topSRT cafs)
281 add_if_missing srt caf =
282 if cafMember srt caf then srt else addCAF caf srt
283 -- If a CAF is more than maxBmpSize entries from the young end of the
284 -- SRT, then we add it to the SRT again.
285 -- (Note: Not in the SRT => infinitely far.)
286 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
287 add srt (sortBy farthestFst cafs)
289 farthestFst x y = case (Map.lookup x m, Map.lookup y m) of
290 (Nothing, Nothing) -> EQ
291 (Nothing, Just _) -> LT
292 (Just _, Nothing) -> GT
293 (Just d, Just d') -> compare d' d
295 add srt@(TopSRT {next_elt = next}) (caf : rst) =
296 case cafOffset srt caf of
297 Just ix -> if next - ix > maxBmpSize then
298 add (addCAF caf srt) rst
300 Nothing -> add (addCAF caf srt) rst
301 (topSRT, subSRTs) <- sub_srt topSRT cafs
302 let (sub_tbls, blockSRTs) = subSRTs
303 return (topSRT, sub_tbls, blockSRTs)
305 -- Construct an SRT bitmap.
306 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
307 procpointSRT :: CLabel -> Map CLabel Int -> [CLabel] ->
308 FuelMonad (Maybe CmmTopZ, C_SRT)
309 procpointSRT _ _ [] =
310 return (Nothing, NoC_SRT)
311 procpointSRT top_srt top_table entries =
312 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
315 ints = map (expectJust "constructSRT" . flip Map.lookup top_table) entries
316 sorted_ints = sortLe (<=) ints
317 offset = head sorted_ints
318 bitmap_entries = map (subtract offset) sorted_ints
319 len = P.last bitmap_entries + 1
320 bitmap = intsToBitmap len bitmap_entries
323 maxBmpSize = widthInBits wordWidth `div` 2
325 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
326 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
327 to_SRT top_srt off len bmp
328 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
329 = do id <- getUniqueM
330 let srt_desc_lbl = mkLargeSRTLabel id
331 tbl = CmmData RelocatableReadOnlyData $
332 CmmDataLabel srt_desc_lbl : map CmmStaticLit
333 ( cmmLabelOffW top_srt off
334 : mkWordCLit (fromIntegral len)
335 : map mkWordCLit bmp)
336 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
338 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
339 -- The fromIntegral converts to StgHalfWord
341 -- Gather CAF info for a procedure, but only if the procedure
342 -- doesn't have a static closure.
343 -- (If it has a static closure, it will already have an SRT to
344 -- keep its CAFs live.)
345 -- Any procedure referring to a non-static CAF c must keep live
346 -- any CAF that is reachable from c.
347 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
348 localCAFInfo _ (CmmData _ _) = Nothing
349 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
351 CmmInfoTable False _ _ _ ->
352 Just (cvtToClosureLbl top_l,
353 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
356 -- Once we have the local CAF sets for some (possibly) mutually
357 -- recursive functions, we can create an environment mapping
358 -- each function to its set of CAFs. Note that a CAF may
359 -- be a reference to a function. If that function f does not have
360 -- a static closure, then we need to refer specifically
361 -- to the set of CAFs used by f. Of course, the set of CAFs
362 -- used by f must be included in the local CAF sets that are input to
363 -- this function. To minimize lookup time later, we return
364 -- the environment with every reference to f replaced by its set of CAFs.
365 -- To do this replacement efficiently, we gather strongly connected
366 -- components, then we sort the components in topological order.
367 mkTopCAFInfo :: [(CLabel, CAFSet)] -> Map CLabel CAFSet
368 mkTopCAFInfo localCAFs = foldl addToTop Map.empty g
369 where addToTop env (AcyclicSCC (l, cafset)) =
370 Map.insert l (flatten env cafset) env
371 addToTop env (CyclicSCC nodes) =
372 let (lbls, cafsets) = unzip nodes
373 cafset = lbls `Map.deleteList` foldl Map.union Map.empty cafsets
374 in foldl (\env l -> Map.insert l (flatten env cafset) env) env lbls
375 flatten env cafset = Map.foldRightWithKey (lookup env) Map.empty cafset
376 lookup env caf () cafset' =
377 case Map.lookup caf env of Just cafs -> Map.foldRightWithKey add cafset' cafs
378 Nothing -> add caf () cafset'
379 add caf () cafset' = Map.insert caf () cafset'
380 g = stronglyConnCompFromEdgedVertices
381 (map (\n@(l, cafs) -> (n, l, Map.keys cafs)) localCAFs)
383 type StackLayout = [Maybe LocalReg]
385 -- Bundle the CAFs used at a procpoint.
386 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
387 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
388 case blockSetToList procpoints of
389 [bid] -> (expectJust "bundleCAFs" (lookupBlockEnv cafEnv bid), t)
390 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
391 -- until we stop splitting the graphs at procpoints in the native path
392 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
393 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
394 bundleCAFs _ t@(NoInfoTable _) = (Map.empty, t)
396 -- Construct the SRTs for the given procedure.
397 setInfoTableSRT :: Map CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
398 FuelMonad (TopSRT, [CmmTopForInfoTables])
399 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
400 case blockSetToList procpoints of
401 [_] -> setSRT cafs topCAFMap topSRT t
402 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
403 -- until we stop splitting the graphs at procpoints in the native path
404 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
405 setSRT cafs topCAFMap topSRT t
406 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
408 setSRT :: CAFSet -> Map CLabel CAFSet -> TopSRT ->
409 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
410 setSRT cafs topCAFMap topSRT t =
411 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
412 let t' = updInfo id (const srt) t
414 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
415 Nothing -> return (topSRT, [t'])
417 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
418 CmmTopForInfoTables -> CmmTopForInfoTables
419 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
420 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
421 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
422 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
423 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
424 updInfo _ _ _ = panic "unexpected arg to updInfo"
426 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
427 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
428 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
429 where typeinfo' = case typeinfo of
430 t@(ConstrInfo _ _ _) -> t
431 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
432 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
433 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
434 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
435 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
437 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
438 -- by emitting info tables as data where necessary.
439 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
440 finishInfoTables (NoInfoTable t) = return [t]
441 finishInfoTables (ProcInfoTable p _) = return [p]
442 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
443 do uniq_supply <- mkSplitUniqSupply 'i'
444 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
446 ----------------------------------------------------------------
447 -- Safe foreign calls:
448 -- Our analyses capture the dataflow facts at block boundaries, but we need
449 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
450 -- which show up as middle nodes.
451 extendEnvWithSafeForeignCalls ::
452 BackwardTransfers Middle Last a -> BlockEnv a -> CmmGraph -> BlockEnv a
453 extendEnvWithSafeForeignCalls transfers env g = fold_blocks block env g
455 tail (bt_last_in transfers l (lookup env)) z head
456 where (head, last) = goto_end (G.unzip b)
457 l = case last of LastOther l -> l
458 LastExit -> panic "extendEnvs lastExit"
459 tail _ z (ZFirst _) = z
460 tail fact env (ZHead h m@(MidForeignCall (Safe bid _ _) _ _ _)) =
461 tail (mid m fact) (extendBlockEnv env bid fact) h
462 tail fact env (ZHead h m) = tail (mid m fact) env h
463 lookup map k = expectJust "extendEnvWithSafeFCalls" $ lookupBlockEnv map k
464 mid = bt_middle_in transfers
467 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
468 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
469 fold_blocks block (cafEnv, slotEnv) g
471 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
472 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
474 where (head, last) = goto_end (G.unzip b)
475 l = case last of LastOther l -> l
476 LastExit -> panic "extendEnvs lastExit"
477 tail _ z (ZFirst _) = z
478 tail lives@(cafs, slots) (cafEnv, slotEnv)
479 (ZHead h m@(MidForeignCall (Safe bid _ _) _ _ _)) =
480 let slots' = removeLiveSlotDefs slots m
481 slotEnv' = extendBlockEnv slotEnv bid slots'
482 cafEnv' = extendBlockEnv cafEnv bid cafs
483 in tail (upd lives m) (cafEnv', slotEnv') h
484 tail lives z (ZHead h m) = tail (upd lives m) z h
485 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
486 upd (cafs, slots) m =
487 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
489 -- Safe foreign calls: We need to insert the code that suspends and resumes
490 -- the thread before and after a safe foreign call.
491 -- Why do we do this so late in the pipeline?
492 -- Because we need this code to appear without interrruption: you can't rely on the
493 -- value of the stack pointer between the call and resetting the thread state;
494 -- you need to have an infotable on the young end of the stack both when
495 -- suspending the thread and making the foreign call.
496 -- All of this is much easier if we insert the suspend and resume calls here.
498 -- At the same time, we prepare for the stages of the compiler that
499 -- build the proc points. We have to do this at the same time because
500 -- the safe foreign calls need special treatment with respect to infotables.
501 -- A safe foreign call needs an infotable even though it isn't
502 -- a procpoint. The following datatype captures the information
503 -- needed to generate the infotables along with the Cmm data and procedures.
505 data CmmTopForInfoTables
506 = NoInfoTable CmmTopZ -- must be CmmData
507 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
508 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
509 instance Outputable CmmTopForInfoTables where
510 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
511 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
512 ppr (FloatingInfoTable info bid upd) =
513 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
515 -- The `safeState' record collects the info we update while lowering the
516 -- safe foreign calls in the graph.
517 data SafeState = State { s_blocks :: BlockEnv CmmBlock
518 , s_pps :: ProcPointSet
519 , s_safeCalls :: [CmmTopForInfoTables]}
521 lowerSafeForeignCalls
522 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
523 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
524 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
525 let init = return $ State emptyBlockEnv emptyBlockSet []
526 let block b@(Block bid _) z = do
527 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
528 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
529 state' = state { s_pps = ppset' }
530 if hasSafeForeignCall b
531 then lowerSafeCallBlock state' b
532 else return (state' { s_blocks = insertBlock b blocks })
533 State blocks' g_procpoints safeCalls <- fold_blocks block init g
534 let proc = (CmmProc info l args (off, LGraph entry blocks'))
535 procTable = case off of
536 (_, Just _) -> [ProcInfoTable proc g_procpoints]
537 _ -> [NoInfoTable proc] -- not a successor of a call
538 return $ safeCalls : procTable : rst
540 -- Check for foreign calls -- if none, then we can avoid copying the block.
541 hasSafeForeignCall :: CmmBlock -> Bool
542 hasSafeForeignCall (Block _ t) = tail t
543 where tail (ZTail (MidForeignCall (Safe _ _ _) _ _ _) _) = True
544 tail (ZTail _ t) = tail t
545 tail (ZLast _) = False
547 -- Lower each safe call in the block, update the CAF and slot environments
548 -- to include each of those calls, and insert the new block in the blockEnv.
549 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
550 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
551 where (head, last) = goto_end (G.unzip b)
552 tail s b@(ZBlock (ZFirst _) _) =
554 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
555 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off _) _ _ _)) t) =
558 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
560 (state'', t') <- lowerSafeForeignCall state' m t
561 tail (return state'') (ZBlock h t')
562 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
565 -- Late in the code generator, we want to insert the code necessary
566 -- to lower a safe foreign call to a sequence of unsafe calls.
567 lowerSafeForeignCall ::
568 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
569 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _ interruptible) _ _ _) tail = do
570 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
571 -- Both 'id' and 'new_base' are KindNonPtr because they're
572 -- RTS-only objects and are not subject to garbage collection
574 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
575 let (caller_save, caller_load) = callerSaveVolatileRegs
576 load_tso <- newTemp gcWord -- TODO FIXME NOW
577 let suspendThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "suspendThread")))
578 resumeThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "resumeThread")))
579 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
582 mkUnsafeCall (ForeignTarget suspendThread
583 (ForeignConvention CCallConv [AddrHint, NoHint] [AddrHint]))
584 -- XXX Not sure if the size of the CmmInt is correct
585 [id] [CmmReg (CmmGlobal BaseReg), CmmLit (CmmInt (fromIntegral (fromEnum interruptible)) wordWidth)]
586 resume = mkUnsafeCall (ForeignTarget resumeThread
587 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
588 [new_base] [CmmReg (CmmLocal id)] <*>
589 -- Assign the result to BaseReg: we
590 -- might now have a different Capability!
591 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
593 loadThreadState load_tso
594 Graph tail' blocks' <-
595 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
596 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
597 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"