--- /dev/null
+module CmmBuildInfoTables
+ ( CAFSet, CAFEnv, cafAnal, localCAFInfo, mkTopCAFInfo
+ , setInfoTableSRT, setInfoTableStackMap
+ , TopSRT, emptySRT, srtToData
+ , finishInfoTables, lowerSafeForeignCalls, extendEnvsForSafeForeignCalls )
+where
+
+#include "HsVersions.h"
+
+import Constants
+import Digraph
+import qualified Prelude as P
+import Prelude
+import Util (sortLe)
+
+import BlockId
+import Bitmap
+import CLabel
+import Cmm hiding (blockId)
+import CmmExpr
+import CmmInfo
+import CmmProcPointZ
+import CmmStackLayout
+import CmmTx
+import DFMonad
+import FastString
+import FiniteMap
+import ForeignCall
+import IdInfo
+import List (sortBy)
+import Maybes
+import MkZipCfg
+import MkZipCfgCmm hiding (CmmAGraph, CmmBlock, CmmTopZ, CmmZ, CmmGraph)
+import Monad
+import Name
+import Outputable
+import Panic
+import SMRep
+import StgCmmClosure
+import StgCmmForeign
+import StgCmmMonad
+import StgCmmUtils
+import UniqSupply
+import ZipCfg hiding (zip, unzip, last)
+import qualified ZipCfg as G
+import ZipCfgCmmRep
+import ZipDataflow
+
+----------------------------------------------------------------
+-- Building InfoTables
+
+
+-----------------------------------------------------------------------
+-- Stack Maps
+
+-- Given a block ID, we return a representation of the layout of the stack,
+-- as suspended before entering that block.
+-- (For a return site to a function call, the layout does not include the
+-- parameter passing area (or the "return address" on the stack)).
+-- If the element is `Nothing`, then it represents a word of the stack that
+-- does not contain a live pointer.
+-- If the element is `Just` a register, then it represents a live spill slot
+-- for a pointer; we assume that a pointer is the size of a word.
+-- The head of the list represents the young end of the stack where the infotable
+-- pointer for the block `Bid` is stored.
+-- The infotable pointer itself is not included in the list.
+-- Call areas are also excluded from the list: besides the stuff in the update
+-- frame (and the return infotable), call areas should never be live across
+-- function calls.
+
+-- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
+-- represents a word. Consequently, we have to be careful when we see a live slot
+-- on the stack: if we have packed multiple sub-word values into a word,
+-- we have to make sure that we only mark the entire word as a non-pointer.
+
+-- Also, don't forget to stop at the old end of the stack (oldByte),
+-- which may differ depending on whether there is an update frame.
+live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
+live_ptrs oldByte slotEnv areaMap bid =
+ pprTrace "live_ptrs for" (ppr bid <+> ppr youngByte <+> ppr liveSlots) $
+ reverse $ slotsToList youngByte liveSlots []
+ where slotsToList n [] results | n == oldByte = results -- at old end of stack frame
+ slotsToList n (s : _) _ | n == oldByte =
+ pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
+ ppr n <+> ppr liveSlots <+> ppr youngByte)
+ slotsToList n _ _ | n < oldByte =
+ panic "stack slots not allocated on word boundaries?"
+ slotsToList n l@((n', r, w) : rst) results =
+ if n == (n' + w) then -- slot's young byte is at n
+ ASSERT (not (isPtr r) ||
+ (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
+ slotsToList next (dropWhile (non_ptr_younger_than next) rst)
+ (stack_rep : results)
+ else slotsToList next (dropWhile (non_ptr_younger_than next) l)
+ (Nothing : results)
+ where next = n - wORD_SIZE
+ stack_rep = if isPtr r then Just r else Nothing
+ slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
+ non_ptr_younger_than next (n', r, w) =
+ n' + w > next &&
+ ASSERT (not (isPtr r))
+ True
+ isPtr = isGcPtrType . localRegType
+ liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
+ (foldFM (\_ -> flip $ foldl add_slot) [] slots)
+
+ add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
+ if off == w && widthInBytes (typeWidth ty) == w then
+ (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
+ else panic "live_ptrs: only part of a variable live at a proc point"
+ add_slot rst (CallArea Old, off, w) =
+ rst -- the update frame (or return infotable) should be live
+ -- would be nice to check that only that part of the callarea is live...
+ add_slot rst c@((CallArea _), _, _) =
+ rst
+ -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
+ -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
+ -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
+ -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
+ -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
+ -- SO IT'S ALL GOING IN THE SAME DIRECTION.
+ -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
+ slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
+ youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
+
+-- Construct the stack maps for the given procedure.
+setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
+setInfoTableStackMap _ _ t@(NoInfoTable _) = t
+setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable info bid updfr_off) =
+ updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
+setInfoTableStackMap slotEnv areaMap
+ t@(ProcInfoTable (CmmProc (CmmInfo _ _ infoTbl) _ _ g@(LGraph entry _ blocks))
+ procpoints) =
+ case blockSetToList procpoints of
+ [bid] ->
+ let oldByte = case infoTbl of
+ CmmInfoTable _ _ _ (ContInfo _ _) ->
+ case lookupBlockEnv blocks bid of
+ Just (Block _ (StackInfo {returnOff = Just n}) _) -> n
+ _ -> pprPanic "misformed graph at procpoint" (ppr g)
+ _ -> initUpdFrameOff -- entry to top-level function
+ stack_vars = live_ptrs oldByte slotEnv areaMap bid
+ in updInfo (const stack_vars) id t
+ _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
+ -- until we stop splitting the graphs at procpoints in the native path
+setInfoTableStackMap _ _ _ = panic "unexpected case for setInfoTableStackMap"
+{-
+setInfoTableStackMap slotEnv areaMap
+ (Just bid, p@(CmmProc (CmmInfo _ _ infoTbl) _ _ g@(LGraph entry _ blocks))) =
+ let oldByte = case infoTbl of
+ CmmInfoTable _ _ _ (ContInfo _ _) ->
+ case lookupBlockEnv blocks bid of
+ Just (Block _ (StackInfo {returnOff = Just n}) _) -> n
+ _ -> pprPanic "misformed graph at procpoint" (ppr g)
+ _ -> initUpdFrameOff -- entry to top-level function
+ stack_vars = live_ptrs oldByte slotEnv areaMap bid
+ in (Just bid, upd_info_tbl (const stack_vars) id p)
+setInfoTableStackMap _ _ t@(_, CmmData {}) = t
+setInfoTableStackMap _ _ _ = panic "bad args to setInfoTableStackMap"
+-}
+
+
+-----------------------------------------------------------------------
+-- SRTs
+
+-- WE NEED AN EXAMPLE HERE.
+-- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
+-- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
+-- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
+-- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
+-- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
+-- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
+
+
+-----------------------------------------------------------------------
+-- Finding the CAFs used by a procedure
+
+type CAFSet = FiniteMap CLabel ()
+type CAFEnv = BlockEnv CAFSet
+
+-- First, an analysis to find live CAFs.
+cafLattice :: DataflowLattice CAFSet
+cafLattice = DataflowLattice "live cafs" emptyFM add True
+ where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
+ where new' = new `plusFM` old
+
+cafTransfers :: BackwardTransfers Middle Last CAFSet
+cafTransfers = BackwardTransfers first middle last
+ where first live _ = live
+ middle live m = pprTrace "cafmiddle" (ppr m) $ foldExpDeepMiddle addCaf m live
+ last env l = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
+ addCaf e set = case e of
+ CmmLit (CmmLabel c) -> add c set
+ CmmLit (CmmLabelOff c _) -> add c set
+ CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
+ _ -> set
+ add l s = pprTrace "CAF analysis saw label" (ppr l) $
+ if hasCAF l then
+ pprTrace "has caf" (ppr l) $ addToFM s (cvtToClosureLbl l) ()
+ else (pprTrace "no cafs" (ppr l) $ s)
+
+type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
+cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
+cafAnal g = liftM zdfFpFacts (res :: CafFix ())
+ where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
+ cafTransfers (fact_bot cafLattice) g
+
+-----------------------------------------------------------------------
+-- Building the SRTs
+
+-- Description of the SRT for a given module.
+-- Note that this SRT may grow as we greedily add new CAFs to it.
+data TopSRT = TopSRT { lbl :: CLabel
+ , next_elt :: Int -- the next entry in the table
+ , rev_elts :: [CLabel]
+ , elt_map :: FiniteMap CLabel Int }
+ -- map: CLabel -> its last entry in the table
+instance Outputable TopSRT where
+ ppr (TopSRT lbl next elts eltmap) =
+ text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
+
+emptySRT :: MonadUnique m => m TopSRT
+emptySRT =
+ do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
+ return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
+
+cafMember :: TopSRT -> CLabel -> Bool
+cafMember srt lbl = elemFM lbl (elt_map srt)
+
+cafOffset :: TopSRT -> CLabel -> Maybe Int
+cafOffset srt lbl = lookupFM (elt_map srt) lbl
+
+addCAF :: CLabel -> TopSRT -> TopSRT
+addCAF caf srt =
+ srt { next_elt = last + 1
+ , rev_elts = caf : rev_elts srt
+ , elt_map = addToFM (elt_map srt) caf last }
+ where last = next_elt srt
+
+srtToData :: TopSRT -> CmmZ
+srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
+ where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
+
+-- Once we have found the CAFs, we need to do two things:
+-- 1. Build a table of all the CAFs used in the procedure.
+-- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
+--
+-- When building the local view of the SRT, we first make sure that all the CAFs are
+-- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
+-- we make sure they're all close enough to the bottom of the table that the
+-- bitmap will be able to cover all of them.
+buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
+ FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
+buildSRTs topSRT topCAFMap cafs =
+ -- This is surely the wrong way to get names, as in BlockId
+ do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
+ let liftCAF lbl () z = -- get CAFs for functions without static closures
+ case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
+ Nothing -> addToFM z lbl ()
+ sub_srt topSRT localCafs =
+ let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
+ mkSRT topSRT =
+ do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
+ return (topSRT, localSRTs)
+ in pprTrace "cafs" (ppr cafs) $
+ if length cafs > maxBmpSize then
+ mkSRT (foldl add_if_missing topSRT cafs)
+ else -- make sure all the cafs are near the bottom of the srt
+ mkSRT (add_if_too_far topSRT cafs)
+ add_if_missing srt caf =
+ if cafMember srt caf then srt else addCAF caf srt
+ -- If a CAF is more than maxBmpSize entries from the young end of the
+ -- SRT, then we add it to the SRT again.
+ -- (Note: Not in the SRT => infinitely far.)
+ add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
+ add srt (sortBy farthestFst cafs)
+ where
+ farthestFst x y = case (lookupFM m x, lookupFM m y) of
+ (Nothing, Nothing) -> EQ
+ (Nothing, Just _) -> LT
+ (Just _, Nothing) -> GT
+ (Just d, Just d') -> compare d' d
+ add srt [] = srt
+ add srt@(TopSRT {next_elt = next}) (caf : rst) =
+ case cafOffset srt caf of
+ Just ix -> if next - ix > maxBmpSize then
+ add (addCAF caf srt) rst
+ else srt
+ Nothing -> add (addCAF caf srt) rst
+ (topSRT, subSRTs) <- sub_srt topSRT cafs
+ let (sub_tbls, blockSRTs) = subSRTs
+ return (topSRT, sub_tbls, blockSRTs)
+
+-- Construct an SRT bitmap.
+-- Adapted from simpleStg/SRT.lhs, which expects Id's.
+procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
+ FuelMonad (Maybe CmmTopZ, C_SRT)
+procpointSRT top_srt top_table [] =
+ return (Nothing, NoC_SRT)
+procpointSRT top_srt top_table entries =
+ do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
+ return (top, srt)
+ where
+ ints = map (expectJust "constructSRT" . lookupFM top_table) entries
+ sorted_ints = sortLe (<=) ints
+ offset = head sorted_ints
+ bitmap_entries = map (subtract offset) sorted_ints
+ len = P.last bitmap_entries + 1
+ bitmap = intsToBitmap len bitmap_entries
+
+maxBmpSize :: Int
+maxBmpSize = widthInBits wordWidth `div` 2
+
+-- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
+to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
+to_SRT top_srt off len bmp
+ | len > maxBmpSize || bmp == [fromIntegral srt_escape]
+ = do id <- getUniqueM
+ let srt_desc_lbl = mkLargeSRTLabel id
+ tbl = CmmData RelocatableReadOnlyData $
+ CmmDataLabel srt_desc_lbl : map CmmStaticLit
+ ( cmmLabelOffW top_srt off
+ : mkWordCLit (fromIntegral len)
+ : map mkWordCLit bmp)
+ return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
+ | otherwise
+ = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
+ -- The fromIntegral converts to StgHalfWord
+
+-- Gather CAF info for a procedure, but only if the procedure
+-- doesn't have a static closure.
+-- (If it has a static closure, it will already have an SRT to
+-- keep its CAFs live.)
+localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
+localCAFInfo _ t@(CmmData _ _) = Nothing
+localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (LGraph entry _ _)) =
+ case infoTbl of
+ CmmInfoTable False _ _ _ ->
+ Just (cvtToClosureLbl top_l,
+ expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
+ _ -> Nothing
+
+-- Once we have the local CAF sets for some (possibly) mutually
+-- recursive functions, we can create an environment mapping
+-- each function to its set of CAFs. Note that a CAF may
+-- be a reference to a function. If that function f does not have
+-- a static closure, then we need to refer specifically
+-- to the set of CAFs used by f. Of course, the set of CAFs
+-- used by f must be included in the local CAF sets that are input to
+-- this function. To minimize lookup time later, we return
+-- the environment with every reference to f replaced by its set of CAFs.
+-- To do this replacement efficiently, we gather strongly connected
+-- components, then we sort the components in topological order.
+mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
+mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
+ where addToTop env (AcyclicSCC (l, cafset)) =
+ addToFM env l (flatten env cafset)
+ addToTop env (CyclicSCC nodes) =
+ let (lbls, cafsets) = unzip nodes
+ cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
+ in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
+ flatten env cafset = foldFM (lookup env) emptyFM cafset
+ lookup env caf () cafset' =
+ case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
+ Nothing -> add caf () cafset'
+ add caf () cafset' = addToFM cafset' caf ()
+ g = stronglyConnCompFromEdgedVertices
+ (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
+
+type StackLayout = [Maybe LocalReg]
+
+-- Construct the SRTs for the given procedure.
+setInfoTableSRT :: CAFEnv -> FiniteMap CLabel CAFSet -> TopSRT ->
+ CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
+setInfoTableSRT cafEnv topCAFMap topSRT t@(ProcInfoTable p procpoints) =
+ case blockSetToList procpoints of
+ [bid] -> setSRT cafEnv topCAFMap topSRT t bid
+ _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
+ -- until we stop splitting the graphs at procpoints in the native path
+setInfoTableSRT cafEnv topCAFMap topSRT t@(FloatingInfoTable info bid _) =
+ setSRT cafEnv topCAFMap topSRT t bid
+setInfoTableSRT _ _ topSRT t@(NoInfoTable _) = return (topSRT, [t])
+
+setSRT :: CAFEnv -> FiniteMap CLabel CAFSet -> TopSRT ->
+ CmmTopForInfoTables -> BlockId -> FuelMonad (TopSRT, [CmmTopForInfoTables])
+setSRT cafEnv topCAFMap topSRT t bid =
+ do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap
+ (expectJust "sub_srt" $ lookupBlockEnv cafEnv bid)
+ let t' = updInfo id (const srt) t
+ case cafTable of
+ Just tbl -> return (topSRT, [t', NoInfoTable tbl])
+ Nothing -> return (topSRT, [t'])
+
+updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
+ CmmTopForInfoTables -> CmmTopForInfoTables
+updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
+ ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
+updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
+ FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
+updInfo toVars toSrt (NoInfoTable _) = panic "can't update NoInfoTable"
+updInfo _ _ _ = panic "unexpected arg to updInfo"
+
+updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
+updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
+ = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
+ where typeinfo' = case typeinfo of
+ t@(ConstrInfo _ _ _) -> t
+ (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
+ (ThunkInfo c s) -> ThunkInfo c (toSrt s)
+ (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
+ (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
+updInfoTbl toVars toSrt t@(CmmInfo _ _ CmmNonInfoTable) = t
+
+-- Lower the CmmTopForInfoTables type down to good old CmmTopZ
+-- by emitting info tables as data where necessary.
+finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
+finishInfoTables (NoInfoTable t) = return [t]
+finishInfoTables (ProcInfoTable p _) = return [p]
+finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
+ do uniq_supply <- mkSplitUniqSupply 'i'
+ return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
+
+----------------------------------------------------------------
+-- Safe foreign calls:
+-- Our analyses capture the dataflow facts at block boundaries, but we need
+-- to extend the CAF and live-slot analyses to safe foreign calls as well,
+-- which show up as middle nodes.
+extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
+extendEnvsForSafeForeignCalls cafEnv slotEnv g =
+ fold_blocks block (cafEnv, slotEnv) g
+ where block b@(Block _ _ t) z =
+ tail ( bt_last_in cafTransfers (lookupFn cafEnv) l
+ , bt_last_in liveSlotTransfers (lookupFn slotEnv) l)
+ z head
+ where (head, last) = goto_end (G.unzip b)
+ l = case last of LastOther l -> l
+ LastExit -> panic "extendEnvs lastExit"
+ tail lives z (ZFirst _ _) = z
+ tail lives@(cafs, slots) (cafEnv, slotEnv)
+ (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) =
+ let slots' = removeLiveSlotDefs slots m
+ slotEnv' = extendBlockEnv slotEnv bid slots'
+ cafEnv' = extendBlockEnv cafEnv bid cafs
+ in tail (upd lives m) (cafEnv', slotEnv') h
+ tail lives z (ZHead h m) = tail (upd lives m) z h
+ lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
+ upd (cafs, slots) m =
+ (bt_middle_in cafTransfers cafs m, bt_middle_in liveSlotTransfers slots m)
+
+-- Safe foreign calls: We need to insert the code that suspends and resumes
+-- the thread before and after a safe foreign call.
+-- Why do we do this so late in the pipeline?
+-- Because we need this code to appear without interrruption: you can't rely on the
+-- value of the stack pointer between the call and resetting the thread state;
+-- you need to have an infotable on the young end of the stack both when
+-- suspending the thread and making the foreign call.
+-- All of this is much easier if we insert the suspend and resume calls here.
+
+-- At the same time, we prepare for the stages of the compiler that
+-- build the proc points. We have to do this at the same time because
+-- the safe foreign calls need special treatment with respect to infotables.
+-- A safe foreign call needs an infotable even though it isn't
+-- a procpoint. The following datatype captures the information
+-- needed to generate the infotables along with the Cmm data and procedures.
+
+data CmmTopForInfoTables
+ = NoInfoTable CmmTopZ -- must be CmmData
+ | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
+ | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
+instance Outputable CmmTopForInfoTables where
+ ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
+ ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
+ ppr (FloatingInfoTable info bid upd) =
+ text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
+
+-- The `safeState' record collects the info we update while lowering the
+-- safe foreign calls in the graph.
+data SafeState = State { s_blocks :: BlockEnv CmmBlock
+ , s_pps :: ProcPointSet
+ , s_safeCalls :: [CmmTopForInfoTables]}
+
+lowerSafeForeignCalls
+ :: ProcPointSet -> [[CmmTopForInfoTables]] ->
+ CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
+lowerSafeForeignCalls _ rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
+lowerSafeForeignCalls procpoints rst
+ t@(CmmProc info l args g@(LGraph entry off blocks)) = do
+ let init = return $ State emptyBlockEnv emptyBlockSet []
+ let block b@(Block bid _ _) z = do
+ state@(State {s_pps = ppset, s_blocks = blocks}) <- z
+ let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
+ state' = state { s_pps = ppset' }
+ if hasSafeForeignCall b
+ then lowerSafeCallBlock state' b
+ else return (state' { s_blocks = insertBlock b blocks })
+ State blocks' g_procpoints safeCalls <- fold_blocks block init g
+ return $ (ProcInfoTable (CmmProc info l args (LGraph entry off blocks')) g_procpoints
+ : safeCalls) : rst
+
+-- Check for foreign calls -- if none, then we can avoid copying the block.
+hasSafeForeignCall :: CmmBlock -> Bool
+hasSafeForeignCall (Block _ _ t) = tail t
+ where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) t) = True
+ tail (ZTail _ t) = tail t
+ tail (ZLast _) = False
+
+-- Lower each safe call in the block, update the CAF and slot environments
+-- to include each of those calls, and insert the new block in the blockEnv.
+lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
+lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
+ where (head, last) = goto_end (G.unzip b)
+ tail s b@(ZBlock (ZFirst _ _) _) =
+ do state <- s
+ return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
+ tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
+ do state <- s
+ let state' = state
+ { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
+ s_safeCalls state }
+ (state'', t') <- lowerSafeForeignCall state' m t
+ tail (return state'') (ZBlock h t')
+ tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
+
+
+-- Late in the code generator, we want to insert the code necessary
+-- to lower a safe foreign call to a sequence of unsafe calls.
+lowerSafeForeignCall ::
+ SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
+lowerSafeForeignCall state m@(MidForeignCall (Safe infotable updfr) _ _ _) tail = do
+ let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
+ -- Both 'id' and 'new_base' are KindNonPtr because they're
+ -- RTS-only objects and are not subject to garbage collection
+ id <- newTemp bWord
+ new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
+ let (caller_save, caller_load) = callerSaveVolatileRegs
+ load_tso <- newTemp gcWord -- TODO FIXME NOW
+ let suspendThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "suspendThread")))
+ resumeThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "resumeThread")))
+ suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
+ saveThreadState <*>
+ caller_save <*>
+ mkUnsafeCall (ForeignTarget suspendThread
+ (ForeignConvention CCallConv [AddrHint] [AddrHint]))
+ [id] [CmmReg (CmmGlobal BaseReg)]
+ resume = mkUnsafeCall (ForeignTarget resumeThread
+ (ForeignConvention CCallConv [AddrHint] [AddrHint]))
+ [new_base] [CmmReg (CmmLocal id)] <*>
+ -- Assign the result to BaseReg: we
+ -- might now have a different Capability!
+ mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
+ caller_load <*>
+ loadThreadState load_tso
+ Graph tail' blocks' <-
+ liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
+ return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
+lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"
projects / ghc-hetmet.git / blobdiff