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)
45 import ZipCfg hiding (zip, unzip, last)
46 import qualified ZipCfg as G
50 ----------------------------------------------------------------
51 -- Building InfoTables
54 -----------------------------------------------------------------------
57 -- Given a block ID, we return a representation of the layout of the stack,
58 -- as suspended before entering that block.
59 -- (For a return site to a function call, the layout does not include the
60 -- parameter passing area (or the "return address" on the stack)).
61 -- If the element is `Nothing`, then it represents a word of the stack that
62 -- does not contain a live pointer.
63 -- If the element is `Just` a register, then it represents a live spill slot
64 -- for a pointer; we assume that a pointer is the size of a word.
65 -- The head of the list represents the young end of the stack where the infotable
66 -- pointer for the block `Bid` is stored.
67 -- The infotable pointer itself is not included in the list.
68 -- Call areas are also excluded from the list: besides the stuff in the update
69 -- frame (and the return infotable), call areas should never be live across
72 -- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
73 -- represents a word. Consequently, we have to be careful when we see a live slot
74 -- on the stack: if we have packed multiple sub-word values into a word,
75 -- we have to make sure that we only mark the entire word as a non-pointer.
77 -- Also, don't forget to stop at the old end of the stack (oldByte),
78 -- which may differ depending on whether there is an update frame.
79 live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
80 live_ptrs oldByte slotEnv areaMap bid =
81 -- pprTrace "live_ptrs for" (ppr bid <+> ppr youngByte <+> ppr liveSlots) $
82 reverse $ slotsToList youngByte liveSlots []
83 where slotsToList n [] results | n == oldByte = results -- at old end of stack frame
84 slotsToList n (s : _) _ | n == oldByte =
85 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
86 ppr n <+> ppr liveSlots <+> ppr youngByte)
87 slotsToList n _ _ | n < oldByte =
88 panic "stack slots not allocated on word boundaries?"
89 slotsToList n l@((n', r, w) : rst) results =
90 if n == (n' + w) then -- slot's young byte is at n
91 ASSERT (not (isPtr r) ||
92 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
93 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
95 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
97 where next = n - wORD_SIZE
98 stack_rep = if isPtr r then Just r else Nothing
99 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
100 non_ptr_younger_than next (n', r, w) =
102 ASSERT (not (isPtr r))
104 isPtr = isGcPtrType . localRegType
105 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
106 (foldFM (\_ -> flip $ foldl add_slot) [] slots)
108 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
109 if off == w && widthInBytes (typeWidth ty) == w then
110 (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
111 else panic "live_ptrs: only part of a variable live at a proc point"
112 add_slot rst (CallArea Old, _, _) =
113 rst -- the update frame (or return infotable) should be live
114 -- would be nice to check that only that part of the callarea is live...
115 add_slot rst ((CallArea _), _, _) =
117 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
118 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
119 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
120 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
121 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
122 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
123 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
124 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
125 youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
127 -- Construct the stack maps for the given procedure.
128 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
129 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
130 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
131 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
132 setInfoTableStackMap slotEnv areaMap
133 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
134 case blockSetToList procpoints of
135 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
136 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
137 -- until we stop splitting the graphs at procpoints in the native path
138 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
142 -----------------------------------------------------------------------
145 -- WE NEED AN EXAMPLE HERE.
146 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
147 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
148 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
149 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
150 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
151 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
154 -----------------------------------------------------------------------
155 -- Finding the CAFs used by a procedure
157 type CAFSet = FiniteMap CLabel ()
158 type CAFEnv = BlockEnv CAFSet
160 -- First, an analysis to find live CAFs.
161 cafLattice :: DataflowLattice CAFSet
162 cafLattice = DataflowLattice "live cafs" emptyFM add False
163 where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
164 where new' = new `plusFM` old
166 cafTransfers :: BackwardTransfers Middle Last CAFSet
167 cafTransfers = BackwardTransfers first middle last
168 where first _ live = live
169 middle m live = foldExpDeepMiddle addCaf m live
170 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
171 addCaf e set = case e of
172 CmmLit (CmmLabel c) -> add c set
173 CmmLit (CmmLabelOff c _) -> add c set
174 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
176 add l s = if hasCAF l then addToFM s (cvtToClosureLbl l) () else s
178 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
179 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
180 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
181 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
182 cafTransfers (fact_bot cafLattice) g
184 -----------------------------------------------------------------------
187 -- Description of the SRT for a given module.
188 -- Note that this SRT may grow as we greedily add new CAFs to it.
189 data TopSRT = TopSRT { lbl :: CLabel
190 , next_elt :: Int -- the next entry in the table
191 , rev_elts :: [CLabel]
192 , elt_map :: FiniteMap CLabel Int }
193 -- map: CLabel -> its last entry in the table
194 instance Outputable TopSRT where
195 ppr (TopSRT lbl next elts eltmap) =
196 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
198 emptySRT :: MonadUnique m => m TopSRT
200 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
201 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
203 cafMember :: TopSRT -> CLabel -> Bool
204 cafMember srt lbl = elemFM lbl (elt_map srt)
206 cafOffset :: TopSRT -> CLabel -> Maybe Int
207 cafOffset srt lbl = lookupFM (elt_map srt) lbl
209 addCAF :: CLabel -> TopSRT -> TopSRT
211 srt { next_elt = last + 1
212 , rev_elts = caf : rev_elts srt
213 , elt_map = addToFM (elt_map srt) caf last }
214 where last = next_elt srt
216 srtToData :: TopSRT -> CmmZ
217 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
218 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
220 -- Once we have found the CAFs, we need to do two things:
221 -- 1. Build a table of all the CAFs used in the procedure.
222 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
224 -- When building the local view of the SRT, we first make sure that all the CAFs are
225 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
226 -- we make sure they're all close enough to the bottom of the table that the
227 -- bitmap will be able to cover all of them.
228 buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
229 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
230 buildSRTs topSRT topCAFMap cafs =
231 do let liftCAF lbl () z = -- get CAFs for functions without static closures
232 case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
233 Nothing -> addToFM z lbl ()
234 sub_srt topSRT localCafs =
235 let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
237 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
238 return (topSRT, localSRTs)
239 in if length cafs > maxBmpSize then
240 mkSRT (foldl add_if_missing topSRT cafs)
241 else -- make sure all the cafs are near the bottom of the srt
242 mkSRT (add_if_too_far topSRT cafs)
243 add_if_missing srt caf =
244 if cafMember srt caf then srt else addCAF caf srt
245 -- If a CAF is more than maxBmpSize entries from the young end of the
246 -- SRT, then we add it to the SRT again.
247 -- (Note: Not in the SRT => infinitely far.)
248 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
249 add srt (sortBy farthestFst cafs)
251 farthestFst x y = case (lookupFM m x, lookupFM m y) of
252 (Nothing, Nothing) -> EQ
253 (Nothing, Just _) -> LT
254 (Just _, Nothing) -> GT
255 (Just d, Just d') -> compare d' d
257 add srt@(TopSRT {next_elt = next}) (caf : rst) =
258 case cafOffset srt caf of
259 Just ix -> if next - ix > maxBmpSize then
260 add (addCAF caf srt) rst
262 Nothing -> add (addCAF caf srt) rst
263 (topSRT, subSRTs) <- sub_srt topSRT cafs
264 let (sub_tbls, blockSRTs) = subSRTs
265 return (topSRT, sub_tbls, blockSRTs)
267 -- Construct an SRT bitmap.
268 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
269 procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
270 FuelMonad (Maybe CmmTopZ, C_SRT)
271 procpointSRT _ _ [] =
272 return (Nothing, NoC_SRT)
273 procpointSRT top_srt top_table entries =
274 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
277 ints = map (expectJust "constructSRT" . lookupFM top_table) entries
278 sorted_ints = sortLe (<=) ints
279 offset = head sorted_ints
280 bitmap_entries = map (subtract offset) sorted_ints
281 len = P.last bitmap_entries + 1
282 bitmap = intsToBitmap len bitmap_entries
285 maxBmpSize = widthInBits wordWidth `div` 2
287 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
288 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
289 to_SRT top_srt off len bmp
290 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
291 = do id <- getUniqueM
292 let srt_desc_lbl = mkLargeSRTLabel id
293 tbl = CmmData RelocatableReadOnlyData $
294 CmmDataLabel srt_desc_lbl : map CmmStaticLit
295 ( cmmLabelOffW top_srt off
296 : mkWordCLit (fromIntegral len)
297 : map mkWordCLit bmp)
298 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
300 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
301 -- The fromIntegral converts to StgHalfWord
303 -- Gather CAF info for a procedure, but only if the procedure
304 -- doesn't have a static closure.
305 -- (If it has a static closure, it will already have an SRT to
306 -- keep its CAFs live.)
307 -- Any procedure referring to a non-static CAF c must keep live the
308 -- any CAF that is reachable from c.
309 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
310 localCAFInfo _ (CmmData _ _) = Nothing
311 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
313 CmmInfoTable False _ _ _ ->
314 Just (cvtToClosureLbl top_l,
315 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
318 -- Once we have the local CAF sets for some (possibly) mutually
319 -- recursive functions, we can create an environment mapping
320 -- each function to its set of CAFs. Note that a CAF may
321 -- be a reference to a function. If that function f does not have
322 -- a static closure, then we need to refer specifically
323 -- to the set of CAFs used by f. Of course, the set of CAFs
324 -- used by f must be included in the local CAF sets that are input to
325 -- this function. To minimize lookup time later, we return
326 -- the environment with every reference to f replaced by its set of CAFs.
327 -- To do this replacement efficiently, we gather strongly connected
328 -- components, then we sort the components in topological order.
329 mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
330 mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
331 where addToTop env (AcyclicSCC (l, cafset)) =
332 addToFM env l (flatten env cafset)
333 addToTop env (CyclicSCC nodes) =
334 let (lbls, cafsets) = unzip nodes
335 cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
336 in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
337 flatten env cafset = foldFM (lookup env) emptyFM cafset
338 lookup env caf () cafset' =
339 case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
340 Nothing -> add caf () cafset'
341 add caf () cafset' = addToFM cafset' caf ()
342 g = stronglyConnCompFromEdgedVertices
343 (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
345 type StackLayout = [Maybe LocalReg]
347 -- Bundle the CAFs used at a procpoint.
348 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
349 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
350 case blockSetToList procpoints of
351 [bid] -> (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
352 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
353 -- until we stop splitting the graphs at procpoints in the native path
354 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
355 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
356 bundleCAFs _ t@(NoInfoTable _) = (emptyFM, t)
358 -- Construct the SRTs for the given procedure.
359 setInfoTableSRT :: FiniteMap CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
360 FuelMonad (TopSRT, [CmmTopForInfoTables])
361 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
362 case blockSetToList procpoints of
363 [_] -> setSRT cafs topCAFMap topSRT t
364 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
365 -- until we stop splitting the graphs at procpoints in the native path
366 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
367 setSRT cafs topCAFMap topSRT t
368 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
370 setSRT :: CAFSet -> FiniteMap CLabel CAFSet -> TopSRT ->
371 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
372 setSRT cafs topCAFMap topSRT t =
373 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
374 let t' = updInfo id (const srt) t
376 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
377 Nothing -> return (topSRT, [t'])
379 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
380 CmmTopForInfoTables -> CmmTopForInfoTables
381 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
382 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
383 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
384 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
385 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
386 updInfo _ _ _ = panic "unexpected arg to updInfo"
388 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
389 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
390 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
391 where typeinfo' = case typeinfo of
392 t@(ConstrInfo _ _ _) -> t
393 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
394 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
395 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
396 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
397 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
399 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
400 -- by emitting info tables as data where necessary.
401 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
402 finishInfoTables (NoInfoTable t) = return [t]
403 finishInfoTables (ProcInfoTable p _) = return [p]
404 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
405 do uniq_supply <- mkSplitUniqSupply 'i'
406 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
408 ----------------------------------------------------------------
409 -- Safe foreign calls:
410 -- Our analyses capture the dataflow facts at block boundaries, but we need
411 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
412 -- which show up as middle nodes.
413 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
414 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
415 fold_blocks block (cafEnv, slotEnv) g
417 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
418 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
420 where (head, last) = goto_end (G.unzip b)
421 l = case last of LastOther l -> l
422 LastExit -> panic "extendEnvs lastExit"
423 tail _ z (ZFirst _) = z
424 tail lives@(cafs, slots) (cafEnv, slotEnv)
425 (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
426 let slots' = removeLiveSlotDefs slots m
427 slotEnv' = extendBlockEnv slotEnv bid slots'
428 cafEnv' = extendBlockEnv cafEnv bid cafs
429 in tail (upd lives m) (cafEnv', slotEnv') h
430 tail lives z (ZHead h m) = tail (upd lives m) z h
431 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
432 upd (cafs, slots) m =
433 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
435 -- Safe foreign calls: We need to insert the code that suspends and resumes
436 -- the thread before and after a safe foreign call.
437 -- Why do we do this so late in the pipeline?
438 -- Because we need this code to appear without interrruption: you can't rely on the
439 -- value of the stack pointer between the call and resetting the thread state;
440 -- you need to have an infotable on the young end of the stack both when
441 -- suspending the thread and making the foreign call.
442 -- All of this is much easier if we insert the suspend and resume calls here.
444 -- At the same time, we prepare for the stages of the compiler that
445 -- build the proc points. We have to do this at the same time because
446 -- the safe foreign calls need special treatment with respect to infotables.
447 -- A safe foreign call needs an infotable even though it isn't
448 -- a procpoint. The following datatype captures the information
449 -- needed to generate the infotables along with the Cmm data and procedures.
451 data CmmTopForInfoTables
452 = NoInfoTable CmmTopZ -- must be CmmData
453 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
454 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
455 instance Outputable CmmTopForInfoTables where
456 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
457 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
458 ppr (FloatingInfoTable info bid upd) =
459 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
461 -- The `safeState' record collects the info we update while lowering the
462 -- safe foreign calls in the graph.
463 data SafeState = State { s_blocks :: BlockEnv CmmBlock
464 , s_pps :: ProcPointSet
465 , s_safeCalls :: [CmmTopForInfoTables]}
467 lowerSafeForeignCalls
468 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
469 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
470 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
471 let init = return $ State emptyBlockEnv emptyBlockSet []
472 let block b@(Block bid _) z = do
473 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
474 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
475 state' = state { s_pps = ppset' }
476 if hasSafeForeignCall b
477 then lowerSafeCallBlock state' b
478 else return (state' { s_blocks = insertBlock b blocks })
479 State blocks' g_procpoints safeCalls <- fold_blocks block init g
480 let proc = (CmmProc info l args (off, LGraph entry blocks'))
481 procTable = case off of
482 (_, Just _) -> [ProcInfoTable proc g_procpoints]
483 _ -> [NoInfoTable proc] -- not a successor of a call
484 return $ safeCalls : procTable : rst
486 -- Check for foreign calls -- if none, then we can avoid copying the block.
487 hasSafeForeignCall :: CmmBlock -> Bool
488 hasSafeForeignCall (Block _ t) = tail t
489 where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) _) = True
490 tail (ZTail _ t) = tail t
491 tail (ZLast _) = False
493 -- Lower each safe call in the block, update the CAF and slot environments
494 -- to include each of those calls, and insert the new block in the blockEnv.
495 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
496 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
497 where (head, last) = goto_end (G.unzip b)
498 tail s b@(ZBlock (ZFirst _) _) =
500 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
501 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
504 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
506 (state'', t') <- lowerSafeForeignCall state' m t
507 tail (return state'') (ZBlock h t')
508 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
511 -- Late in the code generator, we want to insert the code necessary
512 -- to lower a safe foreign call to a sequence of unsafe calls.
513 lowerSafeForeignCall ::
514 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
515 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _) _ _ _) tail = do
516 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
517 -- Both 'id' and 'new_base' are KindNonPtr because they're
518 -- RTS-only objects and are not subject to garbage collection
520 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
521 let (caller_save, caller_load) = callerSaveVolatileRegs
522 load_tso <- newTemp gcWord -- TODO FIXME NOW
523 let suspendThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "suspendThread")))
524 resumeThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "resumeThread")))
525 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
528 mkUnsafeCall (ForeignTarget suspendThread
529 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
530 [id] [CmmReg (CmmGlobal BaseReg)]
531 resume = mkUnsafeCall (ForeignTarget resumeThread
532 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
533 [new_base] [CmmReg (CmmLocal id)] <*>
534 -- Assign the result to BaseReg: we
535 -- might now have a different Capability!
536 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
538 loadThreadState load_tso
539 Graph tail' blocks' <-
540 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
541 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
542 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"