{-# LANGUAGE GADTs #-} -- See Note [Deprecations in Hoopl] in Hoopl module {-# OPTIONS_GHC -fno-warn-warnings-deprecations #-} module CmmBuildInfoTables ( CAFSet, CAFEnv, cafAnal , doSRTs, TopSRT, emptySRT, isEmptySRT, srtToData ) where #include "HsVersions.h" import Hoopl import Digraph import BlockId import Bitmap import CLabel import PprCmmDecl () import Cmm import CmmUtils import CmmInfo import Data.List import DynFlags import Maybes import Outputable import SMRep import UniqSupply import Util import PprCmm() import Data.Map (Map) import qualified Data.Map as Map import Data.Set (Set) import qualified Data.Set as Set import Control.Monad import qualified Prelude as P import Prelude hiding (succ) foldSet :: (a -> b -> b) -> b -> Set a -> b foldSet = Set.foldr ----------------------------------------------------------------------- -- SRTs {- EXAMPLE f = \x. ... g ... where g = \y. ... h ... c1 ... h = \z. ... c2 ... c1 & c2 are CAFs g and h are local functions, but they have no static closures. When we generate code for f, we start with a CmmGroup of four CmmDecls: [ f_closure, f_entry, g_entry, h_entry ] we process each CmmDecl separately in cpsTop, giving us a list of CmmDecls. e.g. for f_entry, we might end up with [ f_entry, f1_ret, f2_proc ] where f1_ret is a return point, and f2_proc is a proc-point. We have a CAFSet for each of these CmmDecls, let's suppose they are [ f_entry{g_closure}, f1_ret{g_closure}, f2_proc{} ] [ g_entry{h_closure, c1_closure} ] [ h_entry{c2_closure} ] Now, note that we cannot use g_closure and h_closure in an SRT, because there are no static closures corresponding to these functions. So we have to flatten out the structure, replacing g_closure and h_closure with their contents: [ f_entry{c2_closure, c1_closure}, f1_ret{c2_closure,c1_closure}, f2_proc{} ] [ g_entry{c2_closure, c1_closure} ] [ h_entry{c2_closure} ] This is what flattenCAFSets is doing. -} ----------------------------------------------------------------------- -- Finding the CAFs used by a procedure type CAFSet = Set CLabel type CAFEnv = BlockEnv CAFSet -- First, an analysis to find live CAFs. cafLattice :: DataflowLattice CAFSet cafLattice = DataflowLattice "live cafs" Set.empty add where add _ (OldFact old) (NewFact new) = case old `Set.union` new of new' -> (changeIf $ Set.size new' > Set.size old, new') cafTransfers :: BwdTransfer CmmNode CAFSet cafTransfers = mkBTransfer3 first middle last where first _ live = live middle m live = foldExpDeep addCaf m live last l live = foldExpDeep addCaf l (joinOutFacts cafLattice l live) 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 = if hasCAF l then Set.insert (toClosureLbl l) s else s cafAnal :: CmmGraph -> CAFEnv cafAnal g = dataflowAnalBwd g [] $ analBwd cafLattice cafTransfers ----------------------------------------------------------------------- -- 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 :: Map 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 $ mkTopSRTLabel u return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = Map.empty } isEmptySRT :: TopSRT -> Bool isEmptySRT srt = null (rev_elts srt) cafMember :: TopSRT -> CLabel -> Bool cafMember srt lbl = Map.member lbl (elt_map srt) cafOffset :: TopSRT -> CLabel -> Maybe Int cafOffset srt lbl = Map.lookup lbl (elt_map srt) addCAF :: CLabel -> TopSRT -> TopSRT addCAF caf srt = srt { next_elt = last + 1 , rev_elts = caf : rev_elts srt , elt_map = Map.insert caf last (elt_map srt) } where last = next_elt srt srtToData :: TopSRT -> CmmGroup srtToData srt = [CmmData RelocatableReadOnlyData (Statics (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. buildSRT :: DynFlags -> TopSRT -> CAFSet -> UniqSM (TopSRT, Maybe CmmDecl, C_SRT) buildSRT dflags topSRT cafs = do let -- For each label referring to a function f without a static closure, -- replace it with the CAFs that are reachable from f. sub_srt topSRT localCafs = let cafs = Set.elems localCafs mkSRT topSRT = do localSRTs <- procpointSRT dflags (lbl topSRT) (elt_map topSRT) cafs return (topSRT, localSRTs) in if length cafs > maxBmpSize dflags 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 (Map.lookup x m, Map.lookup y m) 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 dflags 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 :: DynFlags -> CLabel -> Map CLabel Int -> [CLabel] -> UniqSM (Maybe CmmDecl, C_SRT) procpointSRT _ _ _ [] = return (Nothing, NoC_SRT) procpointSRT dflags top_srt top_table entries = do (top, srt) <- bitmap `seq` to_SRT dflags top_srt offset len bitmap return (top, srt) where ints = map (expectJust "constructSRT" . flip Map.lookup top_table) entries sorted_ints = sort ints offset = head sorted_ints bitmap_entries = map (subtract offset) sorted_ints len = P.last bitmap_entries + 1 bitmap = intsToBitmap dflags len bitmap_entries maxBmpSize :: DynFlags -> Int maxBmpSize dflags = widthInBits (wordWidth dflags) `div` 2 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT. to_SRT :: DynFlags -> CLabel -> Int -> Int -> Bitmap -> UniqSM (Maybe CmmDecl, C_SRT) to_SRT dflags top_srt off len bmp | len > maxBmpSize dflags || bmp == [toStgWord dflags (fromStgHalfWord (srtEscape dflags))] = do id <- getUniqueM let srt_desc_lbl = mkLargeSRTLabel id tbl = CmmData RelocatableReadOnlyData $ Statics srt_desc_lbl $ map CmmStaticLit ( cmmLabelOffW dflags top_srt off : mkWordCLit dflags (fromIntegral len) : map (mkStgWordCLit dflags) bmp) return (Just tbl, C_SRT srt_desc_lbl 0 (srtEscape dflags)) | otherwise = return (Nothing, C_SRT top_srt off (toStgHalfWord dflags (fromStgWord (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.) -- Any procedure referring to a non-static CAF c must keep live -- any CAF that is reachable from c. localCAFInfo :: CAFEnv -> CmmDecl -> (CAFSet, Maybe CLabel) localCAFInfo _ (CmmData _ _) = (Set.empty, Nothing) localCAFInfo cafEnv proc@(CmmProc _ top_l _ (CmmGraph {g_entry=entry})) = case topInfoTable proc of Just (CmmInfoTable { cit_rep = rep }) | not (isStaticRep rep) && not (isStackRep rep) -> (cafs, Just (toClosureLbl top_l)) _other -> (cafs, Nothing) where cafs = expectJust "maybeBindCAFs" $ mapLookup entry cafEnv -- 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 :: [(CAFSet, Maybe CLabel)] -> Map CLabel CAFSet mkTopCAFInfo localCAFs = foldl addToTop Map.empty g where addToTop env (AcyclicSCC (l, cafset)) = Map.insert l (flatten env cafset) env addToTop env (CyclicSCC nodes) = let (lbls, cafsets) = unzip nodes cafset = foldr Set.delete (foldl Set.union Set.empty cafsets) lbls in foldl (\env l -> Map.insert l (flatten env cafset) env) env lbls g = stronglyConnCompFromEdgedVertices [ ((l,cafs), l, Set.elems cafs) | (cafs, Just l) <- localCAFs ] flatten :: Map CLabel CAFSet -> CAFSet -> CAFSet flatten env cafset = foldSet (lookup env) Set.empty cafset where lookup env caf cafset' = case Map.lookup caf env of Just cafs -> foldSet Set.insert cafset' cafs Nothing -> Set.insert caf cafset' bundle :: Map CLabel CAFSet -> (CAFEnv, CmmDecl) -> (CAFSet, Maybe CLabel) -> (BlockEnv CAFSet, CmmDecl) bundle flatmap (env, decl@(CmmProc infos lbl _ g)) (closure_cafs, mb_lbl) = ( mapMapWithKey get_cafs (info_tbls infos), decl ) where entry = g_entry g entry_cafs | Just l <- mb_lbl = expectJust "bundle" $ Map.lookup l flatmap | otherwise = flatten flatmap closure_cafs get_cafs l _ | l == entry = entry_cafs | otherwise = if not (mapMember l env) then pprPanic "bundle" (ppr l <+> ppr lbl <+> ppr (info_tbls infos) $$ ppr env $$ ppr decl) else flatten flatmap $ expectJust "bundle" $ mapLookup l env bundle _flatmap (_, decl) _ = ( mapEmpty, decl ) flattenCAFSets :: [(CAFEnv, [CmmDecl])] -> [(BlockEnv CAFSet, CmmDecl)] flattenCAFSets cpsdecls = zipWith (bundle flatmap) zipped localCAFs where zipped = [ (env,decl) | (env,decls) <- cpsdecls, decl <- decls ] localCAFs = unzipWith localCAFInfo zipped flatmap = mkTopCAFInfo localCAFs -- transitive closure of localCAFs doSRTs :: DynFlags -> TopSRT -> [(CAFEnv, [CmmDecl])] -> IO (TopSRT, [CmmDecl]) doSRTs dflags topSRT tops = do let caf_decls = flattenCAFSets tops us <- mkSplitUniqSupply 'u' let (topSRT', gs') = initUs_ us $ foldM setSRT (topSRT, []) caf_decls return (topSRT', reverse gs' {- Note [reverse gs] -}) where setSRT (topSRT, rst) (caf_map, decl@(CmmProc{})) = do (topSRT, srt_tables, srt_env) <- buildSRTs dflags topSRT caf_map let decl' = updInfoSRTs srt_env decl return (topSRT, decl': srt_tables ++ rst) setSRT (topSRT, rst) (_, decl) = return (topSRT, decl : rst) buildSRTs :: DynFlags -> TopSRT -> BlockEnv CAFSet -> UniqSM (TopSRT, [CmmDecl], BlockEnv C_SRT) buildSRTs dflags top_srt caf_map = foldM doOne (top_srt, [], mapEmpty) (mapToList caf_map) where doOne (top_srt, decls, srt_env) (l, cafs) = do (top_srt, mb_decl, srt) <- buildSRT dflags top_srt cafs return ( top_srt, maybeToList mb_decl ++ decls , mapInsert l srt srt_env ) {- - In each CmmDecl there is a mapping from BlockId -> CmmInfoTable - The one corresponding to g_entry is the closure info table, the rest are continuations. - Each one needs an SRT. - We get the CAFSet for each one from the CAFEnv - flatten gives us [(BlockEnv CAFSet, CmmDecl)] - -} {- Note [reverse gs] It is important to keep the code blocks in the same order, otherwise binary sizes get slightly bigger. I'm not completely sure why this is, perhaps the assembler generates bigger jump instructions for forward refs. --SDM -} updInfoSRTs :: BlockEnv C_SRT -> CmmDecl -> CmmDecl updInfoSRTs srt_env (CmmProc top_info top_l live g) = CmmProc (top_info {info_tbls = mapMapWithKey updInfoTbl (info_tbls top_info)}) top_l live g where updInfoTbl l info_tbl = info_tbl { cit_srt = expectJust "updInfo" $ mapLookup l srt_env } updInfoSRTs _ t = t