1 module CmmBuildInfoTables
2 ( CAFSet, CAFEnv, CmmTopForInfoTables(..), cafAnal, localCAFInfo, mkTopCAFInfo
3 , setInfoTableSRT, setInfoTableStackMap
4 , TopSRT, emptySRT, srtToData
6 , finishInfoTables, lowerSafeForeignCalls, extendEnvsForSafeForeignCalls )
9 #include "HsVersions.h"
13 import qualified Prelude as P
20 import Cmm hiding (blockId)
34 import MkZipCfgCmm hiding (CmmAGraph, CmmBlock, CmmTopZ, CmmZ, CmmGraph)
44 import ZipCfg hiding (zip, unzip, last)
45 import qualified ZipCfg as G
49 ----------------------------------------------------------------
50 -- Building InfoTables
53 -----------------------------------------------------------------------
56 -- Given a block ID, we return a representation of the layout of the stack,
57 -- as suspended before entering that block.
58 -- (For a return site to a function call, the layout does not include the
59 -- parameter passing area (or the "return address" on the stack)).
60 -- If the element is `Nothing`, then it represents a word of the stack that
61 -- does not contain a live pointer.
62 -- If the element is `Just` a register, then it represents a live spill slot
63 -- for a pointer; we assume that a pointer is the size of a word.
64 -- The head of the list represents the young end of the stack where the infotable
65 -- pointer for the block `Bid` is stored.
66 -- The infotable pointer itself is not included in the list.
67 -- Call areas are also excluded from the list: besides the stuff in the update
68 -- frame (and the return infotable), call areas should never be live across
71 -- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
72 -- represents a word. Consequently, we have to be careful when we see a live slot
73 -- on the stack: if we have packed multiple sub-word values into a word,
74 -- we have to make sure that we only mark the entire word as a non-pointer.
76 -- Also, don't forget to stop at the old end of the stack (oldByte),
77 -- which may differ depending on whether there is an update frame.
78 live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
79 live_ptrs oldByte slotEnv areaMap bid =
80 -- pprTrace "live_ptrs for" (ppr bid <+> ppr youngByte <+> ppr liveSlots) $
81 reverse $ slotsToList youngByte liveSlots []
82 where slotsToList n [] results | n == oldByte = results -- at old end of stack frame
83 slotsToList n (s : _) _ | n == oldByte =
84 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
85 ppr n <+> ppr liveSlots <+> ppr youngByte)
86 slotsToList n _ _ | n < oldByte =
87 panic "stack slots not allocated on word boundaries?"
88 slotsToList n l@((n', r, w) : rst) results =
89 if n == (n' + w) then -- slot's young byte is at n
90 ASSERT (not (isPtr r) ||
91 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
92 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
94 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
96 where next = n - wORD_SIZE
97 stack_rep = if isPtr r then Just r else Nothing
98 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
99 non_ptr_younger_than next (n', r, w) =
101 ASSERT (not (isPtr r))
103 isPtr = isGcPtrType . localRegType
104 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
105 (foldFM (\_ -> flip $ foldl add_slot) [] slots)
107 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
108 if off == w && widthInBytes (typeWidth ty) == w then
109 (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
110 else panic "live_ptrs: only part of a variable live at a proc point"
111 add_slot rst (CallArea Old, _, _) =
112 rst -- the update frame (or return infotable) should be live
113 -- would be nice to check that only that part of the callarea is live...
114 add_slot rst ((CallArea _), _, _) =
116 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
117 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
118 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
119 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
120 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
121 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
122 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
123 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
124 youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
126 -- Construct the stack maps for the given procedure.
127 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
128 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
129 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
130 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
131 setInfoTableStackMap slotEnv areaMap
132 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
133 case blockSetToList procpoints of
134 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
135 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
136 -- until we stop splitting the graphs at procpoints in the native path
137 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
141 -----------------------------------------------------------------------
144 -- WE NEED AN EXAMPLE HERE.
145 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
146 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
147 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
148 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
149 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
150 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
153 -----------------------------------------------------------------------
154 -- Finding the CAFs used by a procedure
156 type CAFSet = FiniteMap CLabel ()
157 type CAFEnv = BlockEnv CAFSet
159 -- First, an analysis to find live CAFs.
160 cafLattice :: DataflowLattice CAFSet
161 cafLattice = DataflowLattice "live cafs" emptyFM add False
162 where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
163 where new' = new `plusFM` old
165 cafTransfers :: BackwardTransfers Middle Last CAFSet
166 cafTransfers = BackwardTransfers first middle last
167 where first _ live = live
168 middle m live = foldExpDeepMiddle addCaf m live
169 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
170 addCaf e set = case e of
171 CmmLit (CmmLabel c) -> add c set
172 CmmLit (CmmLabelOff c _) -> add c set
173 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
175 add l s = if hasCAF l then addToFM s (cvtToClosureLbl l) () else s
177 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
178 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
179 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
180 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
181 cafTransfers (fact_bot cafLattice) g
183 -----------------------------------------------------------------------
186 -- Description of the SRT for a given module.
187 -- Note that this SRT may grow as we greedily add new CAFs to it.
188 data TopSRT = TopSRT { lbl :: CLabel
189 , next_elt :: Int -- the next entry in the table
190 , rev_elts :: [CLabel]
191 , elt_map :: FiniteMap CLabel Int }
192 -- map: CLabel -> its last entry in the table
193 instance Outputable TopSRT where
194 ppr (TopSRT lbl next elts eltmap) =
195 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
197 emptySRT :: MonadUnique m => m TopSRT
199 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
200 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
202 cafMember :: TopSRT -> CLabel -> Bool
203 cafMember srt lbl = elemFM lbl (elt_map srt)
205 cafOffset :: TopSRT -> CLabel -> Maybe Int
206 cafOffset srt lbl = lookupFM (elt_map srt) lbl
208 addCAF :: CLabel -> TopSRT -> TopSRT
210 srt { next_elt = last + 1
211 , rev_elts = caf : rev_elts srt
212 , elt_map = addToFM (elt_map srt) caf last }
213 where last = next_elt srt
215 srtToData :: TopSRT -> CmmZ
216 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
217 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
219 -- Once we have found the CAFs, we need to do two things:
220 -- 1. Build a table of all the CAFs used in the procedure.
221 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
223 -- When building the local view of the SRT, we first make sure that all the CAFs are
224 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
225 -- we make sure they're all close enough to the bottom of the table that the
226 -- bitmap will be able to cover all of them.
227 buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
228 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
229 buildSRTs topSRT topCAFMap cafs =
230 do let liftCAF lbl () z = -- get CAFs for functions without static closures
231 case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
232 Nothing -> addToFM z lbl ()
233 sub_srt topSRT localCafs =
234 let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
236 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
237 return (topSRT, localSRTs)
238 in if length cafs > maxBmpSize then
239 mkSRT (foldl add_if_missing topSRT cafs)
240 else -- make sure all the cafs are near the bottom of the srt
241 mkSRT (add_if_too_far topSRT cafs)
242 add_if_missing srt caf =
243 if cafMember srt caf then srt else addCAF caf srt
244 -- If a CAF is more than maxBmpSize entries from the young end of the
245 -- SRT, then we add it to the SRT again.
246 -- (Note: Not in the SRT => infinitely far.)
247 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
248 add srt (sortBy farthestFst cafs)
250 farthestFst x y = case (lookupFM m x, lookupFM m y) of
251 (Nothing, Nothing) -> EQ
252 (Nothing, Just _) -> LT
253 (Just _, Nothing) -> GT
254 (Just d, Just d') -> compare d' d
256 add srt@(TopSRT {next_elt = next}) (caf : rst) =
257 case cafOffset srt caf of
258 Just ix -> if next - ix > maxBmpSize then
259 add (addCAF caf srt) rst
261 Nothing -> add (addCAF caf srt) rst
262 (topSRT, subSRTs) <- sub_srt topSRT cafs
263 let (sub_tbls, blockSRTs) = subSRTs
264 return (topSRT, sub_tbls, blockSRTs)
266 -- Construct an SRT bitmap.
267 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
268 procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
269 FuelMonad (Maybe CmmTopZ, C_SRT)
270 procpointSRT _ _ [] =
271 return (Nothing, NoC_SRT)
272 procpointSRT top_srt top_table entries =
273 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
276 ints = map (expectJust "constructSRT" . lookupFM top_table) entries
277 sorted_ints = sortLe (<=) ints
278 offset = head sorted_ints
279 bitmap_entries = map (subtract offset) sorted_ints
280 len = P.last bitmap_entries + 1
281 bitmap = intsToBitmap len bitmap_entries
284 maxBmpSize = widthInBits wordWidth `div` 2
286 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
287 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
288 to_SRT top_srt off len bmp
289 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
290 = do id <- getUniqueM
291 let srt_desc_lbl = mkLargeSRTLabel id
292 tbl = CmmData RelocatableReadOnlyData $
293 CmmDataLabel srt_desc_lbl : map CmmStaticLit
294 ( cmmLabelOffW top_srt off
295 : mkWordCLit (fromIntegral len)
296 : map mkWordCLit bmp)
297 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
299 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
300 -- The fromIntegral converts to StgHalfWord
302 -- Gather CAF info for a procedure, but only if the procedure
303 -- doesn't have a static closure.
304 -- (If it has a static closure, it will already have an SRT to
305 -- keep its CAFs live.)
306 -- Any procedure referring to a non-static CAF c must keep live the
307 -- any CAF that is reachable from c.
308 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
309 localCAFInfo _ (CmmData _ _) = Nothing
310 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
312 CmmInfoTable False _ _ _ ->
313 Just (cvtToClosureLbl top_l,
314 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
317 -- Once we have the local CAF sets for some (possibly) mutually
318 -- recursive functions, we can create an environment mapping
319 -- each function to its set of CAFs. Note that a CAF may
320 -- be a reference to a function. If that function f does not have
321 -- a static closure, then we need to refer specifically
322 -- to the set of CAFs used by f. Of course, the set of CAFs
323 -- used by f must be included in the local CAF sets that are input to
324 -- this function. To minimize lookup time later, we return
325 -- the environment with every reference to f replaced by its set of CAFs.
326 -- To do this replacement efficiently, we gather strongly connected
327 -- components, then we sort the components in topological order.
328 mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
329 mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
330 where addToTop env (AcyclicSCC (l, cafset)) =
331 addToFM env l (flatten env cafset)
332 addToTop env (CyclicSCC nodes) =
333 let (lbls, cafsets) = unzip nodes
334 cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
335 in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
336 flatten env cafset = foldFM (lookup env) emptyFM cafset
337 lookup env caf () cafset' =
338 case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
339 Nothing -> add caf () cafset'
340 add caf () cafset' = addToFM cafset' caf ()
341 g = stronglyConnCompFromEdgedVertices
342 (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
344 type StackLayout = [Maybe LocalReg]
346 -- Bundle the CAFs used at a procpoint.
347 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
348 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
349 case blockSetToList procpoints of
350 [bid] -> (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
351 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
352 -- until we stop splitting the graphs at procpoints in the native path
353 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
354 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
355 bundleCAFs _ t@(NoInfoTable _) = (emptyFM, t)
357 -- Construct the SRTs for the given procedure.
358 setInfoTableSRT :: FiniteMap CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
359 FuelMonad (TopSRT, [CmmTopForInfoTables])
360 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
361 case blockSetToList procpoints of
362 [_] -> setSRT cafs topCAFMap topSRT t
363 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
364 -- until we stop splitting the graphs at procpoints in the native path
365 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
366 setSRT cafs topCAFMap topSRT t
367 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
369 setSRT :: CAFSet -> FiniteMap CLabel CAFSet -> TopSRT ->
370 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
371 setSRT cafs topCAFMap topSRT t =
372 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
373 let t' = updInfo id (const srt) t
375 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
376 Nothing -> return (topSRT, [t'])
378 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
379 CmmTopForInfoTables -> CmmTopForInfoTables
380 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
381 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
382 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
383 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
384 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
385 updInfo _ _ _ = panic "unexpected arg to updInfo"
387 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
388 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
389 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
390 where typeinfo' = case typeinfo of
391 t@(ConstrInfo _ _ _) -> t
392 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
393 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
394 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
395 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
396 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
398 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
399 -- by emitting info tables as data where necessary.
400 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
401 finishInfoTables (NoInfoTable t) = return [t]
402 finishInfoTables (ProcInfoTable p _) = return [p]
403 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
404 do uniq_supply <- mkSplitUniqSupply 'i'
405 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
407 ----------------------------------------------------------------
408 -- Safe foreign calls:
409 -- Our analyses capture the dataflow facts at block boundaries, but we need
410 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
411 -- which show up as middle nodes.
412 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
413 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
414 fold_blocks block (cafEnv, slotEnv) g
416 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
417 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
419 where (head, last) = goto_end (G.unzip b)
420 l = case last of LastOther l -> l
421 LastExit -> panic "extendEnvs lastExit"
422 tail _ z (ZFirst _) = z
423 tail lives@(cafs, slots) (cafEnv, slotEnv)
424 (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
425 let slots' = removeLiveSlotDefs slots m
426 slotEnv' = extendBlockEnv slotEnv bid slots'
427 cafEnv' = extendBlockEnv cafEnv bid cafs
428 in tail (upd lives m) (cafEnv', slotEnv') h
429 tail lives z (ZHead h m) = tail (upd lives m) z h
430 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
431 upd (cafs, slots) m =
432 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
434 -- Safe foreign calls: We need to insert the code that suspends and resumes
435 -- the thread before and after a safe foreign call.
436 -- Why do we do this so late in the pipeline?
437 -- Because we need this code to appear without interrruption: you can't rely on the
438 -- value of the stack pointer between the call and resetting the thread state;
439 -- you need to have an infotable on the young end of the stack both when
440 -- suspending the thread and making the foreign call.
441 -- All of this is much easier if we insert the suspend and resume calls here.
443 -- At the same time, we prepare for the stages of the compiler that
444 -- build the proc points. We have to do this at the same time because
445 -- the safe foreign calls need special treatment with respect to infotables.
446 -- A safe foreign call needs an infotable even though it isn't
447 -- a procpoint. The following datatype captures the information
448 -- needed to generate the infotables along with the Cmm data and procedures.
450 data CmmTopForInfoTables
451 = NoInfoTable CmmTopZ -- must be CmmData
452 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
453 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
454 instance Outputable CmmTopForInfoTables where
455 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
456 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
457 ppr (FloatingInfoTable info bid upd) =
458 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
460 -- The `safeState' record collects the info we update while lowering the
461 -- safe foreign calls in the graph.
462 data SafeState = State { s_blocks :: BlockEnv CmmBlock
463 , s_pps :: ProcPointSet
464 , s_safeCalls :: [CmmTopForInfoTables]}
466 lowerSafeForeignCalls
467 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
468 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
469 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
470 let init = return $ State emptyBlockEnv emptyBlockSet []
471 let block b@(Block bid _) z = do
472 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
473 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
474 state' = state { s_pps = ppset' }
475 if hasSafeForeignCall b
476 then lowerSafeCallBlock state' b
477 else return (state' { s_blocks = insertBlock b blocks })
478 State blocks' g_procpoints safeCalls <- fold_blocks block init g
479 let proc = (CmmProc info l args (off, LGraph entry blocks'))
480 procTable = case off of
481 (_, Just _) -> [ProcInfoTable proc g_procpoints]
482 _ -> [NoInfoTable proc] -- not a successor of a call
483 return $ safeCalls : procTable : rst
485 -- Check for foreign calls -- if none, then we can avoid copying the block.
486 hasSafeForeignCall :: CmmBlock -> Bool
487 hasSafeForeignCall (Block _ t) = tail t
488 where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) _) = True
489 tail (ZTail _ t) = tail t
490 tail (ZLast _) = False
492 -- Lower each safe call in the block, update the CAF and slot environments
493 -- to include each of those calls, and insert the new block in the blockEnv.
494 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
495 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
496 where (head, last) = goto_end (G.unzip b)
497 tail s b@(ZBlock (ZFirst _) _) =
499 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
500 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
503 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
505 (state'', t') <- lowerSafeForeignCall state' m t
506 tail (return state'') (ZBlock h t')
507 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
510 -- Late in the code generator, we want to insert the code necessary
511 -- to lower a safe foreign call to a sequence of unsafe calls.
512 lowerSafeForeignCall ::
513 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
514 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _) _ _ _) tail = do
515 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
516 -- Both 'id' and 'new_base' are KindNonPtr because they're
517 -- RTS-only objects and are not subject to garbage collection
519 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
520 let (caller_save, caller_load) = callerSaveVolatileRegs
521 load_tso <- newTemp gcWord -- TODO FIXME NOW
522 let suspendThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "suspendThread")))
523 resumeThread = CmmLit (CmmLabel (mkCmmCodeLabel rtsPackageId (fsLit "resumeThread")))
524 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
527 mkUnsafeCall (ForeignTarget suspendThread
528 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
529 [id] [CmmReg (CmmGlobal BaseReg)]
530 resume = mkUnsafeCall (ForeignTarget resumeThread
531 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
532 [new_base] [CmmReg (CmmLocal id)] <*>
533 -- Assign the result to BaseReg: we
534 -- might now have a different Capability!
535 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
537 loadThreadState load_tso
538 Graph tail' blocks' <-
539 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
540 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
541 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"