1 module CmmBuildInfoTables
2 ( CAFSet, CAFEnv, CmmTopForInfoTables(..), cafAnal, localCAFInfo, mkTopCAFInfo
3 , setInfoTableSRT, setInfoTableStackMap
4 , TopSRT, emptySRT, srtToData
6 , finishInfoTables, lowerSafeForeignCalls
7 , cafTransfers, liveSlotTransfers
8 , extendEnvWithSafeForeignCalls, extendEnvsForSafeForeignCalls )
11 #include "HsVersions.h"
15 import qualified Prelude as P
22 import Cmm hiding (blockId)
36 import MkZipCfgCmm hiding (CmmAGraph, CmmBlock, CmmTopZ, CmmZ, CmmGraph)
46 import ZipCfg hiding (zip, unzip, last)
47 import qualified ZipCfg as G
51 ----------------------------------------------------------------
52 -- Building InfoTables
55 -----------------------------------------------------------------------
58 -- Given a block ID, we return a representation of the layout of the stack,
59 -- as suspended before entering that block.
60 -- (For a return site to a function call, the layout does not include the
61 -- parameter passing area (or the "return address" on the stack)).
62 -- If the element is `Nothing`, then it represents a word of the stack that
63 -- does not contain a live pointer.
64 -- If the element is `Just` a register, then it represents a live spill slot
65 -- for a pointer; we assume that a pointer is the size of a word.
66 -- The head of the list represents the young end of the stack where the infotable
67 -- pointer for the block `Bid` is stored.
68 -- The infotable pointer itself is not included in the list.
69 -- Call areas are also excluded from the list: besides the stuff in the update
70 -- frame (and the return infotable), call areas should never be live across
73 -- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
74 -- represents a word. Consequently, we have to be careful when we see a live slot
75 -- on the stack: if we have packed multiple sub-word values into a word,
76 -- we have to make sure that we only mark the entire word as a non-pointer.
78 -- Also, don't forget to stop at the old end of the stack (oldByte),
79 -- which may differ depending on whether there is an update frame.
80 live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
81 live_ptrs oldByte slotEnv areaMap bid =
82 -- pprTrace "live_ptrs for" (ppr bid <+> text (show oldByte ++ "-" ++ show youngByte) <+>
84 -- pprTrace ("stack layout for " ++ show bid ++ ": ") (ppr res) $ res
86 where res = reverse $ slotsToList youngByte liveSlots []
87 slotsToList n [] results | n == oldByte = results -- at old end of stack frame
88 slotsToList n (s : _) _ | n == oldByte =
89 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
90 ppr n <+> ppr liveSlots <+> ppr youngByte)
91 slotsToList n _ _ | n < oldByte =
92 panic "stack slots not allocated on word boundaries?"
93 slotsToList n l@((n', r, w) : rst) results =
94 if n == (n' + w) then -- slot's young byte is at n
95 ASSERT (not (isPtr r) ||
96 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
97 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
99 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
101 where next = n - wORD_SIZE
102 stack_rep = if isPtr r then Just r else Nothing
103 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
104 non_ptr_younger_than next (n', r, w) =
106 ASSERT (not (isPtr r))
108 isPtr = isGcPtrType . localRegType
109 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
110 (foldFM (\_ -> flip $ foldl add_slot) [] slots)
112 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
113 if off == w && widthInBytes (typeWidth ty) == w then
114 (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
115 else panic "live_ptrs: only part of a variable live at a proc point"
116 add_slot rst (CallArea Old, _, _) =
117 rst -- the update frame (or return infotable) should be live
118 -- would be nice to check that only that part of the callarea is live...
119 add_slot rst ((CallArea _), _, _) =
121 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
122 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
123 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
124 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
125 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
126 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
127 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
128 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
129 youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
131 -- Construct the stack maps for the given procedure.
132 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
133 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
134 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
135 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
136 setInfoTableStackMap slotEnv areaMap
137 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
138 case blockSetToList procpoints of
139 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
140 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
141 -- until we stop splitting the graphs at procpoints in the native path
142 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
146 -----------------------------------------------------------------------
149 -- WE NEED AN EXAMPLE HERE.
150 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
151 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
152 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
153 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
154 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
155 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
158 -----------------------------------------------------------------------
159 -- Finding the CAFs used by a procedure
161 type CAFSet = FiniteMap CLabel ()
162 type CAFEnv = BlockEnv CAFSet
164 -- First, an analysis to find live CAFs.
165 cafLattice :: DataflowLattice CAFSet
166 cafLattice = DataflowLattice "live cafs" emptyFM add False
167 where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
168 where new' = new `plusFM` old
170 cafTransfers :: BackwardTransfers Middle Last CAFSet
171 cafTransfers = BackwardTransfers first middle last
172 where first _ live = live
173 middle m live = foldExpDeepMiddle addCaf m live
174 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
175 addCaf e set = case e of
176 CmmLit (CmmLabel c) -> add c set
177 CmmLit (CmmLabelOff c _) -> add c set
178 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
180 add l s = if hasCAF l then addToFM s (cvtToClosureLbl l) () else s
182 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
183 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
184 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
185 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
186 cafTransfers (fact_bot cafLattice) g
188 -----------------------------------------------------------------------
191 -- Description of the SRT for a given module.
192 -- Note that this SRT may grow as we greedily add new CAFs to it.
193 data TopSRT = TopSRT { lbl :: CLabel
194 , next_elt :: Int -- the next entry in the table
195 , rev_elts :: [CLabel]
196 , elt_map :: FiniteMap CLabel Int }
197 -- map: CLabel -> its last entry in the table
198 instance Outputable TopSRT where
199 ppr (TopSRT lbl next elts eltmap) =
200 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
202 emptySRT :: MonadUnique m => m TopSRT
204 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
205 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
207 cafMember :: TopSRT -> CLabel -> Bool
208 cafMember srt lbl = elemFM lbl (elt_map srt)
210 cafOffset :: TopSRT -> CLabel -> Maybe Int
211 cafOffset srt lbl = lookupFM (elt_map srt) lbl
213 addCAF :: CLabel -> TopSRT -> TopSRT
215 srt { next_elt = last + 1
216 , rev_elts = caf : rev_elts srt
217 , elt_map = addToFM (elt_map srt) caf last }
218 where last = next_elt srt
220 srtToData :: TopSRT -> CmmZ
221 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
222 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
224 -- Once we have found the CAFs, we need to do two things:
225 -- 1. Build a table of all the CAFs used in the procedure.
226 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
228 -- When building the local view of the SRT, we first make sure that all the CAFs are
229 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
230 -- we make sure they're all close enough to the bottom of the table that the
231 -- bitmap will be able to cover all of them.
232 buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
233 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
234 buildSRTs topSRT topCAFMap cafs =
235 do let liftCAF lbl () z = -- get CAFs for functions without static closures
236 case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
237 Nothing -> addToFM z lbl ()
238 -- For each label referring to a function f without a static closure,
239 -- replace it with the CAFs that are reachable from f.
240 sub_srt topSRT localCafs =
241 let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
243 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
244 return (topSRT, localSRTs)
245 in if length cafs > maxBmpSize then
246 mkSRT (foldl add_if_missing topSRT cafs)
247 else -- make sure all the cafs are near the bottom of the srt
248 mkSRT (add_if_too_far topSRT cafs)
249 add_if_missing srt caf =
250 if cafMember srt caf then srt else addCAF caf srt
251 -- If a CAF is more than maxBmpSize entries from the young end of the
252 -- SRT, then we add it to the SRT again.
253 -- (Note: Not in the SRT => infinitely far.)
254 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
255 add srt (sortBy farthestFst cafs)
257 farthestFst x y = case (lookupFM m x, lookupFM m y) of
258 (Nothing, Nothing) -> EQ
259 (Nothing, Just _) -> LT
260 (Just _, Nothing) -> GT
261 (Just d, Just d') -> compare d' d
263 add srt@(TopSRT {next_elt = next}) (caf : rst) =
264 case cafOffset srt caf of
265 Just ix -> if next - ix > maxBmpSize then
266 add (addCAF caf srt) rst
268 Nothing -> add (addCAF caf srt) rst
269 (topSRT, subSRTs) <- sub_srt topSRT cafs
270 let (sub_tbls, blockSRTs) = subSRTs
271 return (topSRT, sub_tbls, blockSRTs)
273 -- Construct an SRT bitmap.
274 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
275 procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
276 FuelMonad (Maybe CmmTopZ, C_SRT)
277 procpointSRT _ _ [] =
278 return (Nothing, NoC_SRT)
279 procpointSRT top_srt top_table entries =
280 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
283 ints = map (expectJust "constructSRT" . lookupFM top_table) entries
284 sorted_ints = sortLe (<=) ints
285 offset = head sorted_ints
286 bitmap_entries = map (subtract offset) sorted_ints
287 len = P.last bitmap_entries + 1
288 bitmap = intsToBitmap len bitmap_entries
291 maxBmpSize = widthInBits wordWidth `div` 2
293 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
294 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
295 to_SRT top_srt off len bmp
296 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
297 = do id <- getUniqueM
298 let srt_desc_lbl = mkLargeSRTLabel id
299 tbl = CmmData RelocatableReadOnlyData $
300 CmmDataLabel srt_desc_lbl : map CmmStaticLit
301 ( cmmLabelOffW top_srt off
302 : mkWordCLit (fromIntegral len)
303 : map mkWordCLit bmp)
304 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
306 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
307 -- The fromIntegral converts to StgHalfWord
309 -- Gather CAF info for a procedure, but only if the procedure
310 -- doesn't have a static closure.
311 -- (If it has a static closure, it will already have an SRT to
312 -- keep its CAFs live.)
313 -- Any procedure referring to a non-static CAF c must keep live
314 -- any CAF that is reachable from c.
315 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
316 localCAFInfo _ (CmmData _ _) = Nothing
317 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
319 CmmInfoTable False _ _ _ ->
320 Just (cvtToClosureLbl top_l,
321 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
324 -- Once we have the local CAF sets for some (possibly) mutually
325 -- recursive functions, we can create an environment mapping
326 -- each function to its set of CAFs. Note that a CAF may
327 -- be a reference to a function. If that function f does not have
328 -- a static closure, then we need to refer specifically
329 -- to the set of CAFs used by f. Of course, the set of CAFs
330 -- used by f must be included in the local CAF sets that are input to
331 -- this function. To minimize lookup time later, we return
332 -- the environment with every reference to f replaced by its set of CAFs.
333 -- To do this replacement efficiently, we gather strongly connected
334 -- components, then we sort the components in topological order.
335 mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
336 mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
337 where addToTop env (AcyclicSCC (l, cafset)) =
338 addToFM env l (flatten env cafset)
339 addToTop env (CyclicSCC nodes) =
340 let (lbls, cafsets) = unzip nodes
341 cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
342 in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
343 flatten env cafset = foldFM (lookup env) emptyFM cafset
344 lookup env caf () cafset' =
345 case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
346 Nothing -> add caf () cafset'
347 add caf () cafset' = addToFM cafset' caf ()
348 g = stronglyConnCompFromEdgedVertices
349 (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
351 type StackLayout = [Maybe LocalReg]
353 -- Bundle the CAFs used at a procpoint.
354 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
355 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
356 case blockSetToList procpoints of
357 [bid] -> (expectJust "bundleCAFs" (lookupBlockEnv cafEnv bid), t)
358 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
359 -- until we stop splitting the graphs at procpoints in the native path
360 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
361 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
362 bundleCAFs _ t@(NoInfoTable _) = (emptyFM, t)
364 -- Construct the SRTs for the given procedure.
365 setInfoTableSRT :: FiniteMap CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
366 FuelMonad (TopSRT, [CmmTopForInfoTables])
367 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
368 case blockSetToList procpoints of
369 [_] -> setSRT cafs topCAFMap topSRT t
370 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
371 -- until we stop splitting the graphs at procpoints in the native path
372 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
373 setSRT cafs topCAFMap topSRT t
374 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
376 setSRT :: CAFSet -> FiniteMap CLabel CAFSet -> TopSRT ->
377 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
378 setSRT cafs topCAFMap topSRT t =
379 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
380 let t' = updInfo id (const srt) t
382 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
383 Nothing -> return (topSRT, [t'])
385 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
386 CmmTopForInfoTables -> CmmTopForInfoTables
387 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
388 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
389 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
390 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
391 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
392 updInfo _ _ _ = panic "unexpected arg to updInfo"
394 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
395 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
396 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
397 where typeinfo' = case typeinfo of
398 t@(ConstrInfo _ _ _) -> t
399 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
400 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
401 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
402 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
403 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
405 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
406 -- by emitting info tables as data where necessary.
407 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
408 finishInfoTables (NoInfoTable t) = return [t]
409 finishInfoTables (ProcInfoTable p _) = return [p]
410 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
411 do uniq_supply <- mkSplitUniqSupply 'i'
412 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
414 ----------------------------------------------------------------
415 -- Safe foreign calls:
416 -- Our analyses capture the dataflow facts at block boundaries, but we need
417 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
418 -- which show up as middle nodes.
419 extendEnvWithSafeForeignCalls ::
420 BackwardTransfers Middle Last a -> BlockEnv a -> CmmGraph -> BlockEnv a
421 extendEnvWithSafeForeignCalls transfers env g = fold_blocks block env g
423 tail (bt_last_in transfers l (lookup env)) z head
424 where (head, last) = goto_end (G.unzip b)
425 l = case last of LastOther l -> l
426 LastExit -> panic "extendEnvs lastExit"
427 tail _ z (ZFirst _) = z
428 tail fact env (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
429 tail (mid m fact) (extendBlockEnv env bid fact) h
430 tail fact env (ZHead h m) = tail (mid m fact) env h
431 lookup map k = expectJust "extendEnvWithSafeFCalls" $ lookupBlockEnv map k
432 mid = bt_middle_in transfers
435 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
436 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
437 fold_blocks block (cafEnv, slotEnv) g
439 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
440 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
442 where (head, last) = goto_end (G.unzip b)
443 l = case last of LastOther l -> l
444 LastExit -> panic "extendEnvs lastExit"
445 tail _ z (ZFirst _) = z
446 tail lives@(cafs, slots) (cafEnv, slotEnv)
447 (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
448 let slots' = removeLiveSlotDefs slots m
449 slotEnv' = extendBlockEnv slotEnv bid slots'
450 cafEnv' = extendBlockEnv cafEnv bid cafs
451 in tail (upd lives m) (cafEnv', slotEnv') h
452 tail lives z (ZHead h m) = tail (upd lives m) z h
453 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
454 upd (cafs, slots) m =
455 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
457 -- Safe foreign calls: We need to insert the code that suspends and resumes
458 -- the thread before and after a safe foreign call.
459 -- Why do we do this so late in the pipeline?
460 -- Because we need this code to appear without interrruption: you can't rely on the
461 -- value of the stack pointer between the call and resetting the thread state;
462 -- you need to have an infotable on the young end of the stack both when
463 -- suspending the thread and making the foreign call.
464 -- All of this is much easier if we insert the suspend and resume calls here.
466 -- At the same time, we prepare for the stages of the compiler that
467 -- build the proc points. We have to do this at the same time because
468 -- the safe foreign calls need special treatment with respect to infotables.
469 -- A safe foreign call needs an infotable even though it isn't
470 -- a procpoint. The following datatype captures the information
471 -- needed to generate the infotables along with the Cmm data and procedures.
473 data CmmTopForInfoTables
474 = NoInfoTable CmmTopZ -- must be CmmData
475 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
476 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
477 instance Outputable CmmTopForInfoTables where
478 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
479 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
480 ppr (FloatingInfoTable info bid upd) =
481 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
483 -- The `safeState' record collects the info we update while lowering the
484 -- safe foreign calls in the graph.
485 data SafeState = State { s_blocks :: BlockEnv CmmBlock
486 , s_pps :: ProcPointSet
487 , s_safeCalls :: [CmmTopForInfoTables]}
489 lowerSafeForeignCalls
490 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
491 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
492 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
493 let init = return $ State emptyBlockEnv emptyBlockSet []
494 let block b@(Block bid _) z = do
495 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
496 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
497 state' = state { s_pps = ppset' }
498 if hasSafeForeignCall b
499 then lowerSafeCallBlock state' b
500 else return (state' { s_blocks = insertBlock b blocks })
501 State blocks' g_procpoints safeCalls <- fold_blocks block init g
502 let proc = (CmmProc info l args (off, LGraph entry blocks'))
503 procTable = case off of
504 (_, Just _) -> [ProcInfoTable proc g_procpoints]
505 _ -> [NoInfoTable proc] -- not a successor of a call
506 return $ safeCalls : procTable : rst
508 -- Check for foreign calls -- if none, then we can avoid copying the block.
509 hasSafeForeignCall :: CmmBlock -> Bool
510 hasSafeForeignCall (Block _ t) = tail t
511 where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) _) = True
512 tail (ZTail _ t) = tail t
513 tail (ZLast _) = False
515 -- Lower each safe call in the block, update the CAF and slot environments
516 -- to include each of those calls, and insert the new block in the blockEnv.
517 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
518 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
519 where (head, last) = goto_end (G.unzip b)
520 tail s b@(ZBlock (ZFirst _) _) =
522 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
523 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
526 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
528 (state'', t') <- lowerSafeForeignCall state' m t
529 tail (return state'') (ZBlock h t')
530 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
533 -- Late in the code generator, we want to insert the code necessary
534 -- to lower a safe foreign call to a sequence of unsafe calls.
535 lowerSafeForeignCall ::
536 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
537 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _) _ _ _) tail = do
538 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
539 -- Both 'id' and 'new_base' are KindNonPtr because they're
540 -- RTS-only objects and are not subject to garbage collection
542 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
543 let (caller_save, caller_load) = callerSaveVolatileRegs
544 load_tso <- newTemp gcWord -- TODO FIXME NOW
545 let suspendThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "suspendThread")))
546 resumeThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "resumeThread")))
547 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
550 mkUnsafeCall (ForeignTarget suspendThread
551 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
552 [id] [CmmReg (CmmGlobal BaseReg)]
553 resume = mkUnsafeCall (ForeignTarget resumeThread
554 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
555 [new_base] [CmmReg (CmmLocal id)] <*>
556 -- Assign the result to BaseReg: we
557 -- might now have a different Capability!
558 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
560 loadThreadState load_tso
561 Graph tail' blocks' <-
562 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
563 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
564 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"