{-# LANGUAGE GADTs #-} {-# OPTIONS -fno-warn-tabs #-} -- The above warning supression flag is a temporary kludge. -- While working on this module you are encouraged to remove it and -- detab the module (please do the detabbing in a separate patch). See -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces -- for details -- ToDo: remove -fno-warn-warnings-deprecations {-# OPTIONS_GHC -fno-warn-warnings-deprecations #-} -- ToDo: remove -fno-warn-incomplete-patterns {-# OPTIONS_GHC -fno-warn-incomplete-patterns #-} -- Module for building CmmAGraphs. -- As the CmmAGraph is a wrapper over Graph CmmNode O x, it is different -- from Hoopl's AGraph. The current clients expect functions with the -- same names Hoopl uses, so this module cannot be in the same namespace -- as Compiler.Hoopl. module MkGraph ( CmmAGraph , emptyAGraph, (<*>), catAGraphs, outOfLine , mkLabel, mkMiddle, mkLast , withFreshLabel, withUnique, lgraphOfAGraph, labelAGraph , stackStubExpr , mkNop, mkAssign, mkStore, mkCall, mkCmmCall, mkSafeCall, mkUnsafeCall, mkFinalCall , mkJump, mkDirectJump, mkForeignJump, mkJumpGC, mkCbranch, mkSwitch , mkReturn, mkReturnSimple, mkComment, mkCallEntry , mkBranch, mkCmmIfThenElse, mkCmmIfThen, mkCmmWhileDo , copyInOflow, copyInSlot, copyOutOflow, copyOutSlot ) where import BlockId import Cmm import CmmCallConv (assignArgumentsPos, ParamLocation(..)) import Compiler.Hoopl hiding (Unique, (<*>), mkFirst, mkMiddle, mkLast, mkLabel, mkBranch, Shape(..)) import qualified Compiler.Hoopl as H import Compiler.Hoopl.GHC (uniqueToLbl) import FastString import ForeignCall import Outputable import Prelude hiding (succ) import SMRep (ByteOff) import StaticFlags import Unique import UniqSupply #include "HsVersions.h" {- A 'CmmAGraph' is an abstract version of a 'Graph CmmNode O x' from module 'Cmm'. The difference is that the 'CmmAGraph' can be eigher open of closed at exit and it can supply fresh Labels and Uniques. It also supports a splicing operation <*>, which is different from the Hoopl's <*>, because it splices two CmmAGraphs. Specifically, it can splice Graph O C and Graph O x. In this case, the open beginning of the second graph is thrown away. In the debug mode this sequence is checked to be empty or containing a branch (see note [Branch follows branch]). When an CmmAGraph open at exit is being converted to a CmmGraph, the output exit sequence is considered unreachable. If the graph consist of one block only, if it not the case and we crash. Otherwise we just throw the exit sequence away (and in debug mode we test that it really was unreachable). -} {- Node [Branch follows branch] ============================ Why do we say it's ok for a Branch to follow a Branch? Because the standard constructor mkLabel has fall-through semantics. So if you do a mkLabel, you finish the current block, giving it a label, and start a new one that branches to that label. Emitting a Branch at this point is fine: goto L1; L2: ...stuff... -} data CmmGraphOC = Opened (Graph CmmNode O O) | Closed (Graph CmmNode O C) type CmmAGraph = UniqSM CmmGraphOC -- Graph open at entry {- MS: I began with newtype CmmAGraph = forall x. AG (UniqSM (Graph CmmNode O x)) but that does not work well, because we cannot take the graph out of the monad -- we do not know the type of what we would take out and pattern matching does not help, as we cannot pattern match on a graph inside the monad. -} data Transfer = Call | Jump | Ret deriving Eq ---------- AGraph manipulation emptyAGraph :: CmmAGraph (<*>) :: CmmAGraph -> CmmAGraph -> CmmAGraph catAGraphs :: [CmmAGraph] -> CmmAGraph mkLabel :: BlockId -> CmmAGraph -- created a sequence "goto id; id:" as an AGraph mkMiddle :: CmmNode O O -> CmmAGraph -- creates an open AGraph from a given node mkLast :: CmmNode O C -> CmmAGraph -- created a closed AGraph from a given node withFreshLabel :: String -> (BlockId -> CmmAGraph) -> CmmAGraph withUnique :: (Unique -> CmmAGraph) -> CmmAGraph lgraphOfAGraph :: CmmAGraph -> UniqSM CmmGraph -- ^ allocate a fresh label for the entry point labelAGraph :: BlockId -> CmmAGraph -> UniqSM CmmGraph -- ^ use the given BlockId as the label of the entry point ---------- No-ops mkNop :: CmmAGraph mkComment :: FastString -> CmmAGraph ---------- Assignment and store mkAssign :: CmmReg -> CmmExpr -> CmmAGraph mkStore :: CmmExpr -> CmmExpr -> CmmAGraph ---------- Calls mkCall :: CmmExpr -> (Convention, Convention) -> [CmmFormal] -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkCmmCall :: CmmExpr -> [CmmFormal] -> [CmmActual] -> UpdFrameOffset -> CmmAGraph -- Native C-- calling convention mkSafeCall :: ForeignTarget -> [CmmFormal] -> [CmmActual] -> UpdFrameOffset -> Bool -> CmmAGraph mkUnsafeCall :: ForeignTarget -> [CmmFormal] -> [CmmActual] -> CmmAGraph mkFinalCall :: CmmExpr -> CCallConv -> [CmmActual] -> UpdFrameOffset -> CmmAGraph -- Never returns; like exit() or barf() ---------- Control transfer mkJump :: CmmExpr -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkDirectJump :: CmmExpr -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkJumpGC :: CmmExpr -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkForeignJump :: Convention -> CmmExpr -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkCbranch :: CmmExpr -> BlockId -> BlockId -> CmmAGraph mkSwitch :: CmmExpr -> [Maybe BlockId] -> CmmAGraph mkReturn :: CmmExpr -> [CmmActual] -> UpdFrameOffset -> CmmAGraph mkReturnSimple :: [CmmActual] -> UpdFrameOffset -> CmmAGraph mkBranch :: BlockId -> CmmAGraph mkCmmIfThenElse :: CmmExpr -> CmmAGraph -> CmmAGraph -> CmmAGraph mkCmmIfThen :: CmmExpr -> CmmAGraph -> CmmAGraph mkCmmWhileDo :: CmmExpr -> CmmAGraph -> CmmAGraph outOfLine :: CmmAGraph -> CmmAGraph -- ^ The argument is an CmmAGraph that must have an -- empty entry sequence and be closed at the end. -- The result is a new CmmAGraph that is open at the -- end and goes directly from entry to exit, with the -- original graph sitting to the side out-of-line. -- -- Example: mkMiddle (x = 3) -- <*> outOfLine (mkLabel L <*> ...stuff...) -- <*> mkMiddle (y = x) -- Control will flow directly from x=3 to y=x; -- the block starting with L is "on the side". -- -- N.B. algebraically forall g g' : g <*> outOfLine g' == outOfLine g' <*> g -------------------------------------------------------------------------- -- ================ IMPLEMENTATION ================-- -------------------------------------------------- -- Raw CmmAGraph handling emptyAGraph = return $ Opened emptyGraph ag <*> ah = do g <- ag h <- ah return (case (g, h) of (Opened g, Opened h) -> Opened $ g H.<*> h (Opened g, Closed h) -> Closed $ g H.<*> h (Closed g, Opened GNil) -> Closed g (Closed g, Opened (GUnit e)) -> note_unreachable e $ Closed g (Closed g, Opened (GMany (JustO e) b x)) -> note_unreachable e $ Opened $ g H.|*><*| GMany NothingO b x (Closed g, Closed (GMany (JustO e) b x)) -> note_unreachable e $ Closed $ g H.|*><*| GMany NothingO b x :: CmmGraphOC) catAGraphs = foldl (<*>) emptyAGraph outOfLine ag = withFreshLabel "outOfLine" $ \l -> do g <- ag return (case g of Closed (GMany (JustO e) b _) -> note_unreachable e $ Opened $ GMany (JustO $ BLast $ CmmBranch l) b (JustO $ BFirst $ CmmEntry l) _ -> panic "outOfLine" :: CmmGraphOC) note_unreachable :: Block CmmNode O x -> a -> a note_unreachable block graph = ASSERT (block_is_empty_or_label) -- Note [Branch follows branch] graph where block_is_empty_or_label :: Bool block_is_empty_or_label = case blockToNodeList block of (NothingC, [], NothingC) -> True (NothingC, [], JustC (CmmBranch _)) -> True _ -> False mkLabel bid = return $ Opened $ H.mkLast (CmmBranch bid) |*><*| H.mkFirst (CmmEntry bid) mkMiddle middle = return $ Opened $ H.mkMiddle middle mkLast last = return $ Closed $ H.mkLast last withUnique f = getUniqueM >>= f withFreshLabel _name f = getUniqueM >>= f . uniqueToLbl . intToUnique . getKey lgraphOfAGraph g = do u <- getUniqueM labelAGraph (mkBlockId u) g labelAGraph lbl ag = do g <- ag return $ CmmGraph {g_entry=lbl, g_graph=H.mkFirst (CmmEntry lbl) H.<*> closed g} where closed :: CmmGraphOC -> Graph CmmNode O C closed (Closed g) = g closed (Opened g@(GMany entry body (JustO exit))) = ASSERT (entryLabel exit `notElem` map entryLabel (postorder_dfs g)) GMany entry body NothingO closed (Opened _) = panic "labelAGraph" -------------------------------------------------- -- CmmAGraph constructions mkNop = emptyAGraph mkComment fs = mkMiddle $ CmmComment fs mkStore l r = mkMiddle $ CmmStore l r -- NEED A COMPILER-DEBUGGING FLAG HERE -- Sanity check: any value assigned to a pointer must be non-zero. -- If it's 0, cause a crash immediately. mkAssign l r = if opt_StubDeadValues then assign l r <*> check l else assign l r where assign l r = mkMiddle (CmmAssign l r) check (CmmGlobal _) = mkNop check l@(CmmLocal reg) = -- if a ptr arg is NULL, cause a crash! if isGcPtrType ty then mkCmmIfThen (CmmMachOp (MO_Eq w) [r, stackStubExpr w]) (assign l (CmmLoad (CmmLit (CmmInt 0 w)) ty)) else mkNop where ty = localRegType reg w = typeWidth ty r = CmmReg l -- Why are we inserting extra blocks that simply branch to the successors? -- Because in addition to the branch instruction, @mkBranch@ will insert -- a necessary adjustment to the stack pointer. mkCbranch pred ifso ifnot = mkLast (CmmCondBranch pred ifso ifnot) mkSwitch e tbl = mkLast $ CmmSwitch e tbl mkSafeCall t fs as upd i = withFreshLabel "safe call" $ body where body k = ( mkStore (CmmStackSlot (CallArea (Young k)) (widthInBytes wordWidth)) (CmmLit (CmmBlock k)) <*> mkLast (CmmForeignCall {tgt=t, res=fs, args=as, succ=k, updfr=upd, intrbl=i}) <*> mkLabel k) mkUnsafeCall t fs as = mkMiddle $ CmmUnsafeForeignCall t fs as mkBranch bid = mkLast (CmmBranch bid) mkCmmIfThenElse e tbranch fbranch = withFreshLabel "end of if" $ \endif -> withFreshLabel "start of then" $ \tid -> withFreshLabel "start of else" $ \fid -> mkCbranch e tid fid <*> mkLabel tid <*> tbranch <*> mkBranch endif <*> mkLabel fid <*> fbranch <*> mkLabel endif mkCmmIfThen e tbranch = withFreshLabel "end of if" $ \endif -> withFreshLabel "start of then" $ \tid -> mkCbranch e tid endif <*> mkLabel tid <*> tbranch <*> mkLabel endif mkCmmWhileDo e body = withFreshLabel "loop test" $ \test -> withFreshLabel "loop head" $ \head -> withFreshLabel "end while" $ \endwhile -> -- Forrest Baskett's while-loop layout mkBranch test <*> mkLabel head <*> body <*> mkLabel test <*> mkCbranch e head endwhile <*> mkLabel endwhile -- For debugging purposes, we can stub out dead stack slots: stackStubExpr :: Width -> CmmExpr stackStubExpr w = CmmLit (CmmInt 0 w) -- When we copy in parameters, we usually want to put overflow -- parameters on the stack, but sometimes we want to pass -- the variables in their spill slots. -- Therefore, for copying arguments and results, we provide different -- functions to pass the arguments in an overflow area and to pass them in spill slots. copyInOflow :: Convention -> Area -> [CmmFormal] -> (Int, CmmAGraph) copyInSlot :: Convention -> [CmmFormal] -> [CmmNode O O] copyOutSlot :: Convention -> [LocalReg] -> [CmmNode O O] copyInOflow conv area formals = (offset, catAGraphs $ map mkMiddle nodes) where (offset, nodes) = copyIn oneCopyOflowI conv area formals copyInSlot c f = snd $ copyIn oneCopySlotI c (panic "no area for copying to slots") f type SlotCopier = Area -> (LocalReg, ByteOff) -> (ByteOff, [CmmNode O O]) -> (ByteOff, [CmmNode O O]) type CopyIn = SlotCopier -> Convention -> Area -> [CmmFormal] -> (ByteOff, [CmmNode O O]) -- Return the number of bytes used for copying arguments, as well as the -- instructions to copy the arguments. copyIn :: CopyIn copyIn oflow conv area formals = foldr ci (init_offset, []) args' where ci (reg, RegisterParam r) (n, ms) = (n, CmmAssign (CmmLocal reg) (CmmReg $ CmmGlobal r) : ms) ci (r, StackParam off) (n, ms) = oflow area (r, off) (n, ms) init_offset = widthInBytes wordWidth -- infotable args = assignArgumentsPos conv localRegType formals args' = foldl adjust [] args where adjust rst (v, StackParam off) = (v, StackParam (off + init_offset)) : rst adjust rst x@(_, RegisterParam _) = x : rst -- Copy-in one arg, using overflow space if needed. oneCopyOflowI, oneCopySlotI :: SlotCopier oneCopyOflowI area (reg, off) (n, ms) = (max n off, CmmAssign (CmmLocal reg) (CmmLoad (CmmStackSlot area off) ty) : ms) where ty = localRegType reg -- Copy-in one arg, using spill slots if needed -- used for calling conventions at -- a procpoint that is not a return point. The offset is irrelevant here... oneCopySlotI _ (reg, _) (n, ms) = (n, CmmAssign (CmmLocal reg) (CmmLoad (CmmStackSlot (RegSlot reg) w) ty) : ms) where ty = localRegType reg w = widthInBytes (typeWidth ty) -- Factoring out the common parts of the copyout functions yielded something -- more complicated: copyOutOflow :: Convention -> Transfer -> Area -> [CmmActual] -> UpdFrameOffset -> (Int, CmmAGraph) -- Generate code to move the actual parameters into the locations -- required by the calling convention. This includes a store for the return address. -- -- The argument layout function ignores the pointer to the info table, so we slot that -- in here. When copying-out to a young area, we set the info table for return -- and adjust the offsets of the other parameters. -- If this is a call instruction, we adjust the offsets of the other parameters. copyOutOflow conv transfer area@(CallArea a) actuals updfr_off = foldr co (init_offset, emptyAGraph) args' where co (v, RegisterParam r) (n, ms) = (n, mkAssign (CmmGlobal r) v <*> ms) co (v, StackParam off) (n, ms) = (max n off, mkStore (CmmStackSlot area off) v <*> ms) (setRA, init_offset) = case a of Young id -> id `seq` -- Generate a store instruction for -- the return address if making a call if transfer == Call then ([(CmmLit (CmmBlock id), StackParam init_offset)], widthInBytes wordWidth) else ([], 0) Old -> ([], updfr_off) args :: [(CmmExpr, ParamLocation)] -- The argument and where to put it args = assignArgumentsPos conv cmmExprType actuals args' = foldl adjust setRA args where adjust rst (v, StackParam off) = (v, StackParam (off + init_offset)) : rst adjust rst x@(_, RegisterParam _) = x : rst copyOutOflow _ _ (RegSlot _) _ _ = panic "cannot copy arguments into a register slot" -- Args passed only in registers and stack slots; no overflow space. -- No return address may apply! copyOutSlot conv actuals = foldr co [] args where co (v, RegisterParam r) ms = CmmAssign (CmmGlobal r) (toExp v) : ms co (v, StackParam off) ms = CmmStore (CmmStackSlot (RegSlot v) off) (toExp v) : ms toExp r = CmmReg (CmmLocal r) args = assignArgumentsPos conv localRegType actuals mkCallEntry :: Convention -> [CmmFormal] -> (Int, CmmAGraph) mkCallEntry conv formals = copyInOflow conv (CallArea Old) formals lastWithArgs :: Transfer -> Area -> Convention -> [CmmActual] -> UpdFrameOffset -> (ByteOff -> CmmAGraph) -> CmmAGraph lastWithArgs transfer area conv actuals updfr_off last = let (outArgs, copies) = copyOutOflow conv transfer area actuals updfr_off in copies <*> last outArgs -- The area created for the jump and return arguments is the same area as the -- procedure entry. old :: Area old = CallArea Old toCall :: CmmExpr -> Maybe BlockId -> UpdFrameOffset -> ByteOff -> ByteOff -> CmmAGraph toCall e cont updfr_off res_space arg_space = mkLast $ CmmCall e cont arg_space res_space updfr_off mkJump e actuals updfr_off = lastWithArgs Jump old NativeNodeCall actuals updfr_off $ toCall e Nothing updfr_off 0 mkDirectJump e actuals updfr_off = lastWithArgs Jump old NativeDirectCall actuals updfr_off $ toCall e Nothing updfr_off 0 mkJumpGC e actuals updfr_off = lastWithArgs Jump old GC actuals updfr_off $ toCall e Nothing updfr_off 0 mkForeignJump conv e actuals updfr_off = lastWithArgs Jump old conv actuals updfr_off $ toCall e Nothing updfr_off 0 mkReturn e actuals updfr_off = lastWithArgs Ret old NativeReturn actuals updfr_off $ toCall e Nothing updfr_off 0 -- where e = CmmLoad (CmmStackSlot (CallArea Old) updfr_off) gcWord mkReturnSimple actuals updfr_off = lastWithArgs Ret old NativeReturn actuals updfr_off $ toCall e Nothing updfr_off 0 where e = CmmLoad (CmmStackSlot (CallArea Old) updfr_off) gcWord mkFinalCall f _ actuals updfr_off = lastWithArgs Call old NativeDirectCall actuals updfr_off $ toCall f Nothing updfr_off 0 mkCmmCall f results actuals = mkCall f (NativeDirectCall, NativeReturn) results actuals -- I'm dropping the SRT, but that should be okay: we plan to reconstruct it later. mkCall f (callConv, retConv) results actuals updfr_off = withFreshLabel "call successor" $ \k -> let area = CallArea $ Young k (off, copyin) = copyInOflow retConv area results copyout = lastWithArgs Call area callConv actuals updfr_off (toCall f (Just k) updfr_off off) in (copyout <*> mkLabel k <*> copyin)