{-# LANGUAGE CPP #-} {-# LANGUAGE LambdaCase #-} ----------------------------------------------------------------------------- -- -- Code generator utilities; mostly monadic -- -- (c) The University of Glasgow 2004-2006 -- ----------------------------------------------------------------------------- module GHC.StgToCmm.Utils ( cgLit, mkSimpleLit, emitDataLits, emitRODataLits, emitDataCon, emitRtsCall, emitRtsCallWithResult, emitRtsCallGen, assignTemp, newTemp, newUnboxedTupleRegs, emitMultiAssign, emitCmmLitSwitch, emitSwitch, tagToClosure, mkTaggedObjectLoad, callerSaves, callerSaveVolatileRegs, get_GlobalReg_addr, cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord, cmmUGtWord, cmmSubWord, cmmMulWord, cmmAddWord, cmmUShrWord, cmmOffsetExprW, cmmOffsetExprB, cmmRegOffW, cmmRegOffB, cmmLabelOffW, cmmLabelOffB, cmmOffsetW, cmmOffsetB, cmmOffsetLitW, cmmOffsetLitB, cmmLoadIndexW, cmmConstrTag1, cmmUntag, cmmIsTagged, addToMem, addToMemE, addToMemLblE, addToMemLbl, newStringCLit, newByteStringCLit, -- * Update remembered set operations whenUpdRemSetEnabled, emitUpdRemSetPush, emitUpdRemSetPushThunk, ) where #include "HsVersions.h" import GHC.Prelude import GHC.Platform import GHC.StgToCmm.Monad import GHC.StgToCmm.Closure import GHC.Cmm import GHC.Cmm.BlockId import GHC.Cmm.Graph as CmmGraph import GHC.Platform.Regs import GHC.Cmm.CLabel import GHC.Cmm.Utils import GHC.Cmm.Switch import GHC.StgToCmm.CgUtils import GHC.Types.ForeignCall import GHC.Types.Id.Info import GHC.Core.Type import GHC.Core.TyCon import GHC.Runtime.Heap.Layout import GHC.Unit import GHC.Types.Literal import GHC.Data.Graph.Directed import GHC.Utils.Misc import GHC.Types.Unique import GHC.Types.Unique.Supply (MonadUnique(..)) import GHC.Driver.Session import GHC.Data.FastString import GHC.Utils.Outputable import GHC.Types.RepType import GHC.Types.CostCentre import Data.ByteString (ByteString) import qualified Data.ByteString.Char8 as BS8 import qualified Data.Map as M import Data.Char import Data.List import Data.Ord ------------------------------------------------------------------------- -- -- Literals -- ------------------------------------------------------------------------- cgLit :: Literal -> FCode CmmLit cgLit (LitString s) = newByteStringCLit s -- not unpackFS; we want the UTF-8 byte stream. cgLit other_lit = do platform <- getPlatform return (mkSimpleLit platform other_lit) mkSimpleLit :: Platform -> Literal -> CmmLit mkSimpleLit platform = \case (LitChar c) -> CmmInt (fromIntegral (ord c)) (wordWidth platform) LitNullAddr -> zeroCLit platform (LitNumber LitNumInt i _) -> CmmInt i (wordWidth platform) (LitNumber LitNumInt64 i _) -> CmmInt i W64 (LitNumber LitNumWord i _) -> CmmInt i (wordWidth platform) (LitNumber LitNumWord64 i _) -> CmmInt i W64 (LitFloat r) -> CmmFloat r W32 (LitDouble r) -> CmmFloat r W64 (LitLabel fs ms fod) -> let -- TODO: Literal labels might not actually be in the current package... labelSrc = ForeignLabelInThisPackage in CmmLabel (mkForeignLabel fs ms labelSrc fod) -- NB: LitRubbish should have been lowered in "CoreToStg" other -> pprPanic "mkSimpleLit" (ppr other) -------------------------------------------------------------------------- -- -- Incrementing a memory location -- -------------------------------------------------------------------------- addToMemLbl :: CmmType -> CLabel -> Int -> CmmAGraph addToMemLbl rep lbl n = addToMem rep (CmmLit (CmmLabel lbl)) n addToMemLblE :: CmmType -> CLabel -> CmmExpr -> CmmAGraph addToMemLblE rep lbl = addToMemE rep (CmmLit (CmmLabel lbl)) addToMem :: CmmType -- rep of the counter -> CmmExpr -- Address -> Int -- What to add (a word) -> CmmAGraph addToMem rep ptr n = addToMemE rep ptr (CmmLit (CmmInt (toInteger n) (typeWidth rep))) addToMemE :: CmmType -- rep of the counter -> CmmExpr -- Address -> CmmExpr -- What to add (a word-typed expression) -> CmmAGraph addToMemE rep ptr n = mkStore ptr (CmmMachOp (MO_Add (typeWidth rep)) [CmmLoad ptr rep, n]) ------------------------------------------------------------------------- -- -- Loading a field from an object, -- where the object pointer is itself tagged -- ------------------------------------------------------------------------- mkTaggedObjectLoad :: Platform -> LocalReg -> LocalReg -> ByteOff -> DynTag -> CmmAGraph -- (loadTaggedObjectField reg base off tag) generates assignment -- reg = bitsK[ base + off - tag ] -- where K is fixed by 'reg' mkTaggedObjectLoad platform reg base offset tag = mkAssign (CmmLocal reg) (CmmLoad (cmmOffsetB platform (CmmReg (CmmLocal base)) (offset - tag)) (localRegType reg)) ------------------------------------------------------------------------- -- -- Converting a closure tag to a closure for enumeration types -- (this is the implementation of tagToEnum#). -- ------------------------------------------------------------------------- tagToClosure :: Platform -> TyCon -> CmmExpr -> CmmExpr tagToClosure platform tycon tag = CmmLoad (cmmOffsetExprW platform closure_tbl tag) (bWord platform) where closure_tbl = CmmLit (CmmLabel lbl) lbl = mkClosureTableLabel (tyConName tycon) NoCafRefs ------------------------------------------------------------------------- -- -- Conditionals and rts calls -- ------------------------------------------------------------------------- emitRtsCall :: Unit -> FastString -> [(CmmExpr,ForeignHint)] -> Bool -> FCode () emitRtsCall pkg fun args safe = emitRtsCallGen [] (mkCmmCodeLabel pkg fun) args safe emitRtsCallWithResult :: LocalReg -> ForeignHint -> Unit -> FastString -> [(CmmExpr,ForeignHint)] -> Bool -> FCode () emitRtsCallWithResult res hint pkg fun args safe = emitRtsCallGen [(res,hint)] (mkCmmCodeLabel pkg fun) args safe -- Make a call to an RTS C procedure emitRtsCallGen :: [(LocalReg,ForeignHint)] -> CLabel -> [(CmmExpr,ForeignHint)] -> Bool -- True <=> CmmSafe call -> FCode () emitRtsCallGen res lbl args safe = do { dflags <- getDynFlags ; updfr_off <- getUpdFrameOff ; let (caller_save, caller_load) = callerSaveVolatileRegs dflags ; emit caller_save ; call updfr_off ; emit caller_load } where call updfr_off = if safe then emit =<< mkCmmCall fun_expr res' args' updfr_off else do let conv = ForeignConvention CCallConv arg_hints res_hints CmmMayReturn emit $ mkUnsafeCall (ForeignTarget fun_expr conv) res' args' (args', arg_hints) = unzip args (res', res_hints) = unzip res fun_expr = mkLblExpr lbl ----------------------------------------------------------------------------- -- -- Caller-Save Registers -- ----------------------------------------------------------------------------- -- Here we generate the sequence of saves/restores required around a -- foreign call instruction. -- TODO: reconcile with includes/Regs.h -- * Regs.h claims that BaseReg should be saved last and loaded first -- * This might not have been tickled before since BaseReg is callee save -- * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim -- -- This code isn't actually used right now, because callerSaves -- only ever returns true in the current universe for registers NOT in -- system_regs (just do a grep for CALLER_SAVES in -- includes/stg/MachRegs.h). It's all one giant no-op, and for -- good reason: having to save system registers on every foreign call -- would be very expensive, so we avoid assigning them to those -- registers when we add support for an architecture. -- -- Note that the old code generator actually does more work here: it -- also saves other global registers. We can't (nor want) to do that -- here, as we don't have liveness information. And really, we -- shouldn't be doing the workaround at this point in the pipeline, see -- Note [Register parameter passing] and the ToDo on CmmCall in -- GHC/Cmm/Node.hs. Right now the workaround is to avoid inlining across -- unsafe foreign calls in rewriteAssignments, but this is strictly -- temporary. callerSaveVolatileRegs :: DynFlags -> (CmmAGraph, CmmAGraph) callerSaveVolatileRegs dflags = (caller_save, caller_load) where platform = targetPlatform dflags caller_save = catAGraphs (map callerSaveGlobalReg regs_to_save) caller_load = catAGraphs (map callerRestoreGlobalReg regs_to_save) system_regs = [ Sp,SpLim,Hp,HpLim,CCCS,CurrentTSO,CurrentNursery {- ,SparkHd,SparkTl,SparkBase,SparkLim -} , BaseReg ] regs_to_save = filter (callerSaves platform) system_regs callerSaveGlobalReg reg = mkStore (get_GlobalReg_addr dflags reg) (CmmReg (CmmGlobal reg)) callerRestoreGlobalReg reg = mkAssign (CmmGlobal reg) (CmmLoad (get_GlobalReg_addr dflags reg) (globalRegType platform reg)) ------------------------------------------------------------------------- -- -- Strings generate a top-level data block -- ------------------------------------------------------------------------- -- | Emit a data-segment data block emitDataLits :: CLabel -> [CmmLit] -> FCode () emitDataLits lbl lits = emitDecl (mkDataLits (Section Data lbl) lbl lits) -- | Emit a read-only data block emitRODataLits :: CLabel -> [CmmLit] -> FCode () emitRODataLits lbl lits = emitDecl (mkRODataLits lbl lits) emitDataCon :: CLabel -> CmmInfoTable -> CostCentreStack -> [CmmLit] -> FCode () emitDataCon lbl itbl ccs payload = emitDecl (CmmData (Section Data lbl) (CmmStatics lbl itbl ccs payload)) newStringCLit :: String -> FCode CmmLit -- Make a global definition for the string, -- and return its label newStringCLit str = newByteStringCLit (BS8.pack str) newByteStringCLit :: ByteString -> FCode CmmLit newByteStringCLit bytes = do { uniq <- newUnique ; let (lit, decl) = mkByteStringCLit (mkStringLitLabel uniq) bytes ; emitDecl decl ; return lit } ------------------------------------------------------------------------- -- -- Assigning expressions to temporaries -- ------------------------------------------------------------------------- assignTemp :: CmmExpr -> FCode LocalReg -- Make sure the argument is in a local register. -- We don't bother being particularly aggressive with avoiding -- unnecessary local registers, since we can rely on a later -- optimization pass to inline as necessary (and skipping out -- on things like global registers can be a little dangerous -- due to them being trashed on foreign calls--though it means -- the optimization pass doesn't have to do as much work) assignTemp (CmmReg (CmmLocal reg)) = return reg assignTemp e = do { platform <- getPlatform ; uniq <- newUnique ; let reg = LocalReg uniq (cmmExprType platform e) ; emitAssign (CmmLocal reg) e ; return reg } newTemp :: MonadUnique m => CmmType -> m LocalReg newTemp rep = do { uniq <- getUniqueM ; return (LocalReg uniq rep) } newUnboxedTupleRegs :: Type -> FCode ([LocalReg], [ForeignHint]) -- Choose suitable local regs to use for the components -- of an unboxed tuple that we are about to return to -- the Sequel. If the Sequel is a join point, using the -- regs it wants will save later assignments. newUnboxedTupleRegs res_ty = ASSERT( isUnboxedTupleType res_ty ) do { platform <- getPlatform ; sequel <- getSequel ; regs <- choose_regs platform sequel ; ASSERT( regs `equalLength` reps ) return (regs, map primRepForeignHint reps) } where reps = typePrimRep res_ty choose_regs _ (AssignTo regs _) = return regs choose_regs platform _ = mapM (newTemp . primRepCmmType platform) reps ------------------------------------------------------------------------- -- emitMultiAssign ------------------------------------------------------------------------- emitMultiAssign :: [LocalReg] -> [CmmExpr] -> FCode () -- Emit code to perform the assignments in the -- input simultaneously, using temporary variables when necessary. type Key = Int type Vrtx = (Key, Stmt) -- Give each vertex a unique number, -- for fast comparison type Stmt = (LocalReg, CmmExpr) -- r := e -- We use the strongly-connected component algorithm, in which -- * the vertices are the statements -- * an edge goes from s1 to s2 iff -- s1 assigns to something s2 uses -- that is, if s1 should *follow* s2 in the final order emitMultiAssign [] [] = return () emitMultiAssign [reg] [rhs] = emitAssign (CmmLocal reg) rhs emitMultiAssign regs rhss = do platform <- getPlatform ASSERT2( equalLength regs rhss, ppr regs $$ ppr rhss ) unscramble platform ([1..] `zip` (regs `zip` rhss)) unscramble :: Platform -> [Vrtx] -> FCode () unscramble platform vertices = mapM_ do_component components where edges :: [ Node Key Vrtx ] edges = [ DigraphNode vertex key1 (edges_from stmt1) | vertex@(key1, stmt1) <- vertices ] edges_from :: Stmt -> [Key] edges_from stmt1 = [ key2 | (key2, stmt2) <- vertices, stmt1 `mustFollow` stmt2 ] components :: [SCC Vrtx] components = stronglyConnCompFromEdgedVerticesUniq edges -- do_components deal with one strongly-connected component -- Not cyclic, or singleton? Just do it do_component :: SCC Vrtx -> FCode () do_component (AcyclicSCC (_,stmt)) = mk_graph stmt do_component (CyclicSCC []) = panic "do_component" do_component (CyclicSCC [(_,stmt)]) = mk_graph stmt -- Cyclic? Then go via temporaries. Pick one to -- break the loop and try again with the rest. do_component (CyclicSCC ((_,first_stmt) : rest)) = do u <- newUnique let (to_tmp, from_tmp) = split u first_stmt mk_graph to_tmp unscramble platform rest mk_graph from_tmp split :: Unique -> Stmt -> (Stmt, Stmt) split uniq (reg, rhs) = ((tmp, rhs), (reg, CmmReg (CmmLocal tmp))) where rep = cmmExprType platform rhs tmp = LocalReg uniq rep mk_graph :: Stmt -> FCode () mk_graph (reg, rhs) = emitAssign (CmmLocal reg) rhs mustFollow :: Stmt -> Stmt -> Bool (reg, _) `mustFollow` (_, rhs) = regUsedIn platform (CmmLocal reg) rhs ------------------------------------------------------------------------- -- mkSwitch ------------------------------------------------------------------------- emitSwitch :: CmmExpr -- Tag to switch on -> [(ConTagZ, CmmAGraphScoped)] -- Tagged branches -> Maybe CmmAGraphScoped -- Default branch (if any) -> ConTagZ -> ConTagZ -- Min and Max possible values; -- behaviour outside this range is -- undefined -> FCode () -- First, two rather common cases in which there is no work to do emitSwitch _ [] (Just code) _ _ = emit (fst code) emitSwitch _ [(_,code)] Nothing _ _ = emit (fst code) -- Right, off we go emitSwitch tag_expr branches mb_deflt lo_tag hi_tag = do join_lbl <- newBlockId mb_deflt_lbl <- label_default join_lbl mb_deflt branches_lbls <- label_branches join_lbl branches tag_expr' <- assignTemp' tag_expr -- Sort the branches before calling mk_discrete_switch let branches_lbls' = [ (fromIntegral i, l) | (i,l) <- sortBy (comparing fst) branches_lbls ] let range = (fromIntegral lo_tag, fromIntegral hi_tag) emit $ mk_discrete_switch False tag_expr' branches_lbls' mb_deflt_lbl range emitLabel join_lbl mk_discrete_switch :: Bool -- ^ Use signed comparisons -> CmmExpr -> [(Integer, BlockId)] -> Maybe BlockId -> (Integer, Integer) -> CmmAGraph -- SINGLETON TAG RANGE: no case analysis to do mk_discrete_switch _ _tag_expr [(tag, lbl)] _ (lo_tag, hi_tag) | lo_tag == hi_tag = ASSERT( tag == lo_tag ) mkBranch lbl -- SINGLETON BRANCH, NO DEFAULT: no case analysis to do mk_discrete_switch _ _tag_expr [(_tag,lbl)] Nothing _ = mkBranch lbl -- The simplifier might have eliminated a case -- so we may have e.g. case xs of -- [] -> e -- In that situation we can be sure the (:) case -- can't happen, so no need to test -- SOMETHING MORE COMPLICATED: defer to GHC.Cmm.Switch.Implement -- See Note [Cmm Switches, the general plan] in GHC.Cmm.Switch mk_discrete_switch signed tag_expr branches mb_deflt range = mkSwitch tag_expr $ mkSwitchTargets signed range mb_deflt (M.fromList branches) divideBranches :: Ord a => [(a,b)] -> ([(a,b)], a, [(a,b)]) divideBranches branches = (lo_branches, mid, hi_branches) where -- 2 branches => n_branches `div` 2 = 1 -- => branches !! 1 give the *second* tag -- There are always at least 2 branches here (mid,_) = branches !! (length branches `div` 2) (lo_branches, hi_branches) = span is_lo branches is_lo (t,_) = t < mid -------------- emitCmmLitSwitch :: CmmExpr -- Tag to switch on -> [(Literal, CmmAGraphScoped)] -- Tagged branches -> CmmAGraphScoped -- Default branch (always) -> FCode () -- Emit the code emitCmmLitSwitch _scrut [] deflt = emit $ fst deflt emitCmmLitSwitch scrut branches deflt = do scrut' <- assignTemp' scrut join_lbl <- newBlockId deflt_lbl <- label_code join_lbl deflt branches_lbls <- label_branches join_lbl branches platform <- getPlatform let cmm_ty = cmmExprType platform scrut rep = typeWidth cmm_ty -- We find the necessary type information in the literals in the branches let signed = case head branches of (LitNumber nt _ _, _) -> litNumIsSigned nt _ -> False let range | signed = (platformMinInt platform, platformMaxInt platform) | otherwise = (0, platformMaxWord platform) if isFloatType cmm_ty then emit =<< mk_float_switch rep scrut' deflt_lbl noBound branches_lbls else emit $ mk_discrete_switch signed scrut' [(litValue lit,l) | (lit,l) <- branches_lbls] (Just deflt_lbl) range emitLabel join_lbl -- | lower bound (inclusive), upper bound (exclusive) type LitBound = (Maybe Literal, Maybe Literal) noBound :: LitBound noBound = (Nothing, Nothing) mk_float_switch :: Width -> CmmExpr -> BlockId -> LitBound -> [(Literal,BlockId)] -> FCode CmmAGraph mk_float_switch rep scrut deflt _bounds [(lit,blk)] = do platform <- getPlatform return $ mkCbranch (cond platform) deflt blk Nothing where cond platform = CmmMachOp ne [scrut, CmmLit cmm_lit] where cmm_lit = mkSimpleLit platform lit ne = MO_F_Ne rep mk_float_switch rep scrut deflt_blk_id (lo_bound, hi_bound) branches = do platform <- getPlatform lo_blk <- mk_float_switch rep scrut deflt_blk_id bounds_lo lo_branches hi_blk <- mk_float_switch rep scrut deflt_blk_id bounds_hi hi_branches mkCmmIfThenElse (cond platform) lo_blk hi_blk where (lo_branches, mid_lit, hi_branches) = divideBranches branches bounds_lo = (lo_bound, Just mid_lit) bounds_hi = (Just mid_lit, hi_bound) cond platform = CmmMachOp lt [scrut, CmmLit cmm_lit] where cmm_lit = mkSimpleLit platform mid_lit lt = MO_F_Lt rep -------------- label_default :: BlockId -> Maybe CmmAGraphScoped -> FCode (Maybe BlockId) label_default _ Nothing = return Nothing label_default join_lbl (Just code) = do lbl <- label_code join_lbl code return (Just lbl) -------------- label_branches :: BlockId -> [(a,CmmAGraphScoped)] -> FCode [(a,BlockId)] label_branches _join_lbl [] = return [] label_branches join_lbl ((tag,code):branches) = do lbl <- label_code join_lbl code branches' <- label_branches join_lbl branches return ((tag,lbl):branches') -------------- label_code :: BlockId -> CmmAGraphScoped -> FCode BlockId -- label_code J code -- generates -- [L: code; goto J] -- and returns L label_code join_lbl (code,tsc) = do lbl <- newBlockId emitOutOfLine lbl (code CmmGraph.<*> mkBranch join_lbl, tsc) return lbl -------------- assignTemp' :: CmmExpr -> FCode CmmExpr assignTemp' e | isTrivialCmmExpr e = return e | otherwise = do platform <- getPlatform lreg <- newTemp (cmmExprType platform e) let reg = CmmLocal lreg emitAssign reg e return (CmmReg reg) --------------------------------------------------------------------------- -- Pushing to the update remembered set --------------------------------------------------------------------------- whenUpdRemSetEnabled :: FCode a -> FCode () whenUpdRemSetEnabled code = do platform <- getPlatform do_it <- getCode code let enabled = CmmLoad (CmmLit $ CmmLabel mkNonmovingWriteBarrierEnabledLabel) (bWord platform) zero = zeroExpr platform is_enabled = cmmNeWord platform enabled zero the_if <- mkCmmIfThenElse' is_enabled do_it mkNop (Just False) emit the_if -- | Emit code to add an entry to a now-overwritten pointer to the update -- remembered set. emitUpdRemSetPush :: CmmExpr -- ^ value of pointer which was overwritten -> FCode () emitUpdRemSetPush ptr = do emitRtsCall rtsUnitId (fsLit "updateRemembSetPushClosure_") [(CmmReg (CmmGlobal BaseReg), AddrHint), (ptr, AddrHint)] False emitUpdRemSetPushThunk :: CmmExpr -- ^ the thunk -> FCode () emitUpdRemSetPushThunk ptr = do emitRtsCall rtsUnitId (fsLit "updateRemembSetPushThunk_") [(CmmReg (CmmGlobal BaseReg), AddrHint), (ptr, AddrHint)] False