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 <+> ppr youngByte <+> ppr liveSlots) $
83 reverse $ slotsToList youngByte liveSlots []
84 where slotsToList n [] results | n == oldByte = results -- at old end of stack frame
85 slotsToList n (s : _) _ | n == oldByte =
86 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
87 ppr n <+> ppr liveSlots <+> ppr youngByte)
88 slotsToList n _ _ | n < oldByte =
89 panic "stack slots not allocated on word boundaries?"
90 slotsToList n l@((n', r, w) : rst) results =
91 if n == (n' + w) then -- slot's young byte is at n
92 ASSERT (not (isPtr r) ||
93 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
94 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
96 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
98 where next = n - wORD_SIZE
99 stack_rep = if isPtr r then Just r else Nothing
100 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
101 non_ptr_younger_than next (n', r, w) =
103 ASSERT (not (isPtr r))
105 isPtr = isGcPtrType . localRegType
106 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
107 (foldFM (\_ -> flip $ foldl add_slot) [] slots)
109 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
110 if off == w && widthInBytes (typeWidth ty) == w then
111 (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
112 else panic "live_ptrs: only part of a variable live at a proc point"
113 add_slot rst (CallArea Old, _, _) =
114 rst -- the update frame (or return infotable) should be live
115 -- would be nice to check that only that part of the callarea is live...
116 add_slot rst ((CallArea _), _, _) =
118 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
119 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
120 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
121 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
122 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
123 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
124 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
125 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
126 youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
128 -- Construct the stack maps for the given procedure.
129 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
130 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
131 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
132 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
133 setInfoTableStackMap slotEnv areaMap
134 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
135 case blockSetToList procpoints of
136 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
137 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
138 -- until we stop splitting the graphs at procpoints in the native path
139 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
143 -----------------------------------------------------------------------
146 -- WE NEED AN EXAMPLE HERE.
147 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
148 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
149 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
150 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
151 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
152 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
155 -----------------------------------------------------------------------
156 -- Finding the CAFs used by a procedure
158 type CAFSet = FiniteMap CLabel ()
159 type CAFEnv = BlockEnv CAFSet
161 -- First, an analysis to find live CAFs.
162 cafLattice :: DataflowLattice CAFSet
163 cafLattice = DataflowLattice "live cafs" emptyFM add False
164 where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
165 where new' = new `plusFM` old
167 cafTransfers :: BackwardTransfers Middle Last CAFSet
168 cafTransfers = BackwardTransfers first middle last
169 where first _ live = live
170 middle m live = foldExpDeepMiddle addCaf m live
171 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
172 addCaf e set = case e of
173 CmmLit (CmmLabel c) -> add c set
174 CmmLit (CmmLabelOff c _) -> add c set
175 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
177 add l s = if hasCAF l then addToFM s (cvtToClosureLbl l) () else s
179 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
180 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
181 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
182 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
183 cafTransfers (fact_bot cafLattice) g
185 -----------------------------------------------------------------------
188 -- Description of the SRT for a given module.
189 -- Note that this SRT may grow as we greedily add new CAFs to it.
190 data TopSRT = TopSRT { lbl :: CLabel
191 , next_elt :: Int -- the next entry in the table
192 , rev_elts :: [CLabel]
193 , elt_map :: FiniteMap CLabel Int }
194 -- map: CLabel -> its last entry in the table
195 instance Outputable TopSRT where
196 ppr (TopSRT lbl next elts eltmap) =
197 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
199 emptySRT :: MonadUnique m => m TopSRT
201 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
202 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
204 cafMember :: TopSRT -> CLabel -> Bool
205 cafMember srt lbl = elemFM lbl (elt_map srt)
207 cafOffset :: TopSRT -> CLabel -> Maybe Int
208 cafOffset srt lbl = lookupFM (elt_map srt) lbl
210 addCAF :: CLabel -> TopSRT -> TopSRT
212 srt { next_elt = last + 1
213 , rev_elts = caf : rev_elts srt
214 , elt_map = addToFM (elt_map srt) caf last }
215 where last = next_elt srt
217 srtToData :: TopSRT -> CmmZ
218 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
219 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
221 -- Once we have found the CAFs, we need to do two things:
222 -- 1. Build a table of all the CAFs used in the procedure.
223 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
225 -- When building the local view of the SRT, we first make sure that all the CAFs are
226 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
227 -- we make sure they're all close enough to the bottom of the table that the
228 -- bitmap will be able to cover all of them.
229 buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
230 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
231 buildSRTs topSRT topCAFMap cafs =
232 do let liftCAF lbl () z = -- get CAFs for functions without static closures
233 case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
234 Nothing -> addToFM z lbl ()
235 -- For each label referring to a function f without a static closure,
236 -- replace it with the CAFs that are reachable from f.
237 sub_srt topSRT localCafs =
238 let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
240 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
241 return (topSRT, localSRTs)
242 in if length cafs > maxBmpSize then
243 mkSRT (foldl add_if_missing topSRT cafs)
244 else -- make sure all the cafs are near the bottom of the srt
245 mkSRT (add_if_too_far topSRT cafs)
246 add_if_missing srt caf =
247 if cafMember srt caf then srt else addCAF caf srt
248 -- If a CAF is more than maxBmpSize entries from the young end of the
249 -- SRT, then we add it to the SRT again.
250 -- (Note: Not in the SRT => infinitely far.)
251 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
252 add srt (sortBy farthestFst cafs)
254 farthestFst x y = case (lookupFM m x, lookupFM m y) of
255 (Nothing, Nothing) -> EQ
256 (Nothing, Just _) -> LT
257 (Just _, Nothing) -> GT
258 (Just d, Just d') -> compare d' d
260 add srt@(TopSRT {next_elt = next}) (caf : rst) =
261 case cafOffset srt caf of
262 Just ix -> if next - ix > maxBmpSize then
263 add (addCAF caf srt) rst
265 Nothing -> add (addCAF caf srt) rst
266 (topSRT, subSRTs) <- sub_srt topSRT cafs
267 let (sub_tbls, blockSRTs) = subSRTs
268 return (topSRT, sub_tbls, blockSRTs)
270 -- Construct an SRT bitmap.
271 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
272 procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
273 FuelMonad (Maybe CmmTopZ, C_SRT)
274 procpointSRT _ _ [] =
275 return (Nothing, NoC_SRT)
276 procpointSRT top_srt top_table entries =
277 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
280 ints = map (expectJust "constructSRT" . lookupFM top_table) entries
281 sorted_ints = sortLe (<=) ints
282 offset = head sorted_ints
283 bitmap_entries = map (subtract offset) sorted_ints
284 len = P.last bitmap_entries + 1
285 bitmap = intsToBitmap len bitmap_entries
288 maxBmpSize = widthInBits wordWidth `div` 2
290 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
291 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
292 to_SRT top_srt off len bmp
293 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
294 = do id <- getUniqueM
295 let srt_desc_lbl = mkLargeSRTLabel id
296 tbl = CmmData RelocatableReadOnlyData $
297 CmmDataLabel srt_desc_lbl : map CmmStaticLit
298 ( cmmLabelOffW top_srt off
299 : mkWordCLit (fromIntegral len)
300 : map mkWordCLit bmp)
301 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
303 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
304 -- The fromIntegral converts to StgHalfWord
306 -- Gather CAF info for a procedure, but only if the procedure
307 -- doesn't have a static closure.
308 -- (If it has a static closure, it will already have an SRT to
309 -- keep its CAFs live.)
310 -- Any procedure referring to a non-static CAF c must keep live
311 -- any CAF that is reachable from c.
312 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
313 localCAFInfo _ (CmmData _ _) = Nothing
314 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
316 CmmInfoTable False _ _ _ ->
317 Just (cvtToClosureLbl top_l,
318 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
321 -- Once we have the local CAF sets for some (possibly) mutually
322 -- recursive functions, we can create an environment mapping
323 -- each function to its set of CAFs. Note that a CAF may
324 -- be a reference to a function. If that function f does not have
325 -- a static closure, then we need to refer specifically
326 -- to the set of CAFs used by f. Of course, the set of CAFs
327 -- used by f must be included in the local CAF sets that are input to
328 -- this function. To minimize lookup time later, we return
329 -- the environment with every reference to f replaced by its set of CAFs.
330 -- To do this replacement efficiently, we gather strongly connected
331 -- components, then we sort the components in topological order.
332 mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
333 mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
334 where addToTop env (AcyclicSCC (l, cafset)) =
335 addToFM env l (flatten env cafset)
336 addToTop env (CyclicSCC nodes) =
337 let (lbls, cafsets) = unzip nodes
338 cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
339 in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
340 flatten env cafset = foldFM (lookup env) emptyFM cafset
341 lookup env caf () cafset' =
342 case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
343 Nothing -> add caf () cafset'
344 add caf () cafset' = addToFM cafset' caf ()
345 g = stronglyConnCompFromEdgedVertices
346 (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
348 type StackLayout = [Maybe LocalReg]
350 -- Bundle the CAFs used at a procpoint.
351 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
352 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
353 case blockSetToList procpoints of
354 [bid] -> (expectJust "bundleCAFs" (lookupBlockEnv cafEnv bid), t)
355 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
356 -- until we stop splitting the graphs at procpoints in the native path
357 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
358 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
359 bundleCAFs _ t@(NoInfoTable _) = (emptyFM, t)
361 -- Construct the SRTs for the given procedure.
362 setInfoTableSRT :: FiniteMap CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
363 FuelMonad (TopSRT, [CmmTopForInfoTables])
364 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
365 case blockSetToList procpoints of
366 [_] -> setSRT cafs topCAFMap topSRT t
367 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
368 -- until we stop splitting the graphs at procpoints in the native path
369 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
370 setSRT cafs topCAFMap topSRT t
371 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
373 setSRT :: CAFSet -> FiniteMap CLabel CAFSet -> TopSRT ->
374 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
375 setSRT cafs topCAFMap topSRT t =
376 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
377 let t' = updInfo id (const srt) t
379 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
380 Nothing -> return (topSRT, [t'])
382 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
383 CmmTopForInfoTables -> CmmTopForInfoTables
384 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
385 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
386 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
387 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
388 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
389 updInfo _ _ _ = panic "unexpected arg to updInfo"
391 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
392 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
393 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
394 where typeinfo' = case typeinfo of
395 t@(ConstrInfo _ _ _) -> t
396 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
397 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
398 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
399 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
400 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
402 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
403 -- by emitting info tables as data where necessary.
404 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
405 finishInfoTables (NoInfoTable t) = return [t]
406 finishInfoTables (ProcInfoTable p _) = return [p]
407 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
408 do uniq_supply <- mkSplitUniqSupply 'i'
409 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
411 ----------------------------------------------------------------
412 -- Safe foreign calls:
413 -- Our analyses capture the dataflow facts at block boundaries, but we need
414 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
415 -- which show up as middle nodes.
416 extendEnvWithSafeForeignCalls ::
417 BackwardTransfers Middle Last a -> BlockEnv a -> CmmGraph -> BlockEnv a
418 extendEnvWithSafeForeignCalls transfers env g = fold_blocks block env g
420 tail (bt_last_in transfers l (lookup env)) z head
421 where (head, last) = goto_end (G.unzip b)
422 l = case last of LastOther l -> l
423 LastExit -> panic "extendEnvs lastExit"
424 tail _ z (ZFirst _) = z
425 tail fact env (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
426 tail (mid m fact) (extendBlockEnv env bid fact) h
427 tail fact env (ZHead h m) = tail (mid m fact) env h
428 lookup map k = expectJust "extendEnvWithSafeFCalls" $ lookupBlockEnv map k
429 mid = bt_middle_in transfers
432 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
433 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
434 fold_blocks block (cafEnv, slotEnv) g
436 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
437 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
439 where (head, last) = goto_end (G.unzip b)
440 l = case last of LastOther l -> l
441 LastExit -> panic "extendEnvs lastExit"
442 tail _ z (ZFirst _) = z
443 tail lives@(cafs, slots) (cafEnv, slotEnv)
444 (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
445 let slots' = removeLiveSlotDefs slots m
446 slotEnv' = extendBlockEnv slotEnv bid slots'
447 cafEnv' = extendBlockEnv cafEnv bid cafs
448 in tail (upd lives m) (cafEnv', slotEnv') h
449 tail lives z (ZHead h m) = tail (upd lives m) z h
450 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
451 upd (cafs, slots) m =
452 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
454 -- Safe foreign calls: We need to insert the code that suspends and resumes
455 -- the thread before and after a safe foreign call.
456 -- Why do we do this so late in the pipeline?
457 -- Because we need this code to appear without interrruption: you can't rely on the
458 -- value of the stack pointer between the call and resetting the thread state;
459 -- you need to have an infotable on the young end of the stack both when
460 -- suspending the thread and making the foreign call.
461 -- All of this is much easier if we insert the suspend and resume calls here.
463 -- At the same time, we prepare for the stages of the compiler that
464 -- build the proc points. We have to do this at the same time because
465 -- the safe foreign calls need special treatment with respect to infotables.
466 -- A safe foreign call needs an infotable even though it isn't
467 -- a procpoint. The following datatype captures the information
468 -- needed to generate the infotables along with the Cmm data and procedures.
470 data CmmTopForInfoTables
471 = NoInfoTable CmmTopZ -- must be CmmData
472 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
473 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
474 instance Outputable CmmTopForInfoTables where
475 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
476 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
477 ppr (FloatingInfoTable info bid upd) =
478 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
480 -- The `safeState' record collects the info we update while lowering the
481 -- safe foreign calls in the graph.
482 data SafeState = State { s_blocks :: BlockEnv CmmBlock
483 , s_pps :: ProcPointSet
484 , s_safeCalls :: [CmmTopForInfoTables]}
486 lowerSafeForeignCalls
487 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
488 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
489 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
490 let init = return $ State emptyBlockEnv emptyBlockSet []
491 let block b@(Block bid _) z = do
492 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
493 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
494 state' = state { s_pps = ppset' }
495 if hasSafeForeignCall b
496 then lowerSafeCallBlock state' b
497 else return (state' { s_blocks = insertBlock b blocks })
498 State blocks' g_procpoints safeCalls <- fold_blocks block init g
499 let proc = (CmmProc info l args (off, LGraph entry blocks'))
500 procTable = case off of
501 (_, Just _) -> [ProcInfoTable proc g_procpoints]
502 _ -> [NoInfoTable proc] -- not a successor of a call
503 return $ safeCalls : procTable : rst
505 -- Check for foreign calls -- if none, then we can avoid copying the block.
506 hasSafeForeignCall :: CmmBlock -> Bool
507 hasSafeForeignCall (Block _ t) = tail t
508 where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) _) = True
509 tail (ZTail _ t) = tail t
510 tail (ZLast _) = False
512 -- Lower each safe call in the block, update the CAF and slot environments
513 -- to include each of those calls, and insert the new block in the blockEnv.
514 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
515 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
516 where (head, last) = goto_end (G.unzip b)
517 tail s b@(ZBlock (ZFirst _) _) =
519 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
520 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
523 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
525 (state'', t') <- lowerSafeForeignCall state' m t
526 tail (return state'') (ZBlock h t')
527 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
530 -- Late in the code generator, we want to insert the code necessary
531 -- to lower a safe foreign call to a sequence of unsafe calls.
532 lowerSafeForeignCall ::
533 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
534 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _) _ _ _) tail = do
535 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
536 -- Both 'id' and 'new_base' are KindNonPtr because they're
537 -- RTS-only objects and are not subject to garbage collection
539 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
540 let (caller_save, caller_load) = callerSaveVolatileRegs
541 load_tso <- newTemp gcWord -- TODO FIXME NOW
542 let suspendThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "suspendThread")))
543 resumeThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "resumeThread")))
544 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
547 mkUnsafeCall (ForeignTarget suspendThread
548 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
549 [id] [CmmReg (CmmGlobal BaseReg)]
550 resume = mkUnsafeCall (ForeignTarget resumeThread
551 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
552 [new_base] [CmmReg (CmmLocal id)] <*>
553 -- Assign the result to BaseReg: we
554 -- might now have a different Capability!
555 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
557 loadThreadState load_tso
558 Graph tail' blocks' <-
559 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
560 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
561 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"