X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmCPS.hs;h=2726ef83041d3e84bef53fc7fe54a107bba3499c;hb=bdfa9495e95ba5701f27711b27d8e22ae7bb8335;hp=4ec2fc60f15935d29be70ee306d3f850871974af;hpb=d0f6db5b0cf1189d84e292aeca350211f3b810dd;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmCPS.hs b/compiler/cmm/CmmCPS.hs index 4ec2fc6..2726ef8 100644 --- a/compiler/cmm/CmmCPS.hs +++ b/compiler/cmm/CmmCPS.hs @@ -1,4 +1,8 @@ -module CmmCPS (cmmCPS) where +module CmmCPS ( + -- | Converts C-- with full proceedures and parameters + -- to a CPS transformed C-- with the stack made manifest. + cmmCPS +) where #include "HsVersions.h" @@ -6,20 +10,37 @@ import Cmm import CmmLint import PprCmm -import Dataflow (mapCmmTop, onBasicBlock, cmmLivenessComment, cmmLiveness) +import Dataflow +import CmmLive +import CmmBrokenBlock +import CmmProcPoint +import CmmCallConv + +import MachOp +import ForeignCall +import CLabel +import SMRep +import Constants import DynFlags import ErrUtils import Maybes import Outputable +import UniqSupply +import UniqFM +import UniqSet +import Unique import Monad import IO +import Data.List -cmmCPS :: DynFlags - -> [Cmm] -- C-- with Proceedures - -> IO [Cmm] -- Output: CPS transformed C-- - +----------------------------------------------------------------------------- +-- |Top level driver for the CPS pass +----------------------------------------------------------------------------- +cmmCPS :: DynFlags -- ^ Dynamic flags: -dcmm-lint -ddump-cps-cmm + -> [Cmm] -- ^ Input C-- with Proceedures + -> IO [Cmm] -- ^ Output CPS transformed C-- cmmCPS dflags abstractC = do when (dopt Opt_DoCmmLinting dflags) $ do showPass dflags "CmmLint" @@ -28,9 +49,292 @@ cmmCPS dflags abstractC = do ghcExit dflags 1 Nothing -> return () showPass dflags "CPS" - -- continuationC <- return abstractC - continuationC <- return $ map (mapCmmTop (onBasicBlock (\bs -> map (cmmLivenessComment (cmmLiveness bs)) bs))) abstractC + + -- TODO: more lint checking + -- check for use of branches to non-existant blocks + -- check for use of Sp, SpLim, R1, R2, etc. + + uniqSupply <- mkSplitUniqSupply 'p' + let supplies = listSplitUniqSupply uniqSupply + let doCpsProc s (Cmm c) = + Cmm $ concat $ zipWith cpsProc (listSplitUniqSupply s) c + let continuationC = zipWith doCpsProc supplies abstractC dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC) + -- TODO: add option to dump Cmm to file + return continuationC + +----------------------------------------------------------------------------- +-- |CPS a single CmmTop (proceedure) +-- Only 'CmmProc' are transformed 'CmmData' will be left alone. +----------------------------------------------------------------------------- + +cpsProc :: UniqSupply + -> CmmTop -- ^Input proceedure + -> [CmmTop] -- ^Output proceedure and continuations +cpsProc uniqSupply x@(CmmData _ _) = [x] +cpsProc uniqSupply x@(CmmProc info_table ident params blocks) = cps_procs + where + uniqes :: [[Unique]] + uniqes = map uniqsFromSupply $ listSplitUniqSupply uniqSupply + + -- Break the block at each function call. + -- The part after the function call will have to become a continuation. + broken_blocks :: [BrokenBlock] + broken_blocks = + concat $ zipWith3 breakBlock uniqes blocks + (FunctionEntry ident params:repeat ControlEntry) + + -- Calculate live variables for each broken block. + -- + -- Nothing can be live on entry to the first block + -- so we could take the tail, but for now we wont + -- to help future proof the code. + live :: BlockEntryLiveness + live = cmmLiveness $ map cmmBlockFromBrokenBlock broken_blocks + + -- Calculate which blocks must be made into full fledged procedures. + proc_points :: UniqSet BlockId + proc_points = calculateProcPoints broken_blocks + + -- Construct a map so we can lookup a broken block by its 'BlockId'. + block_env :: BlockEnv BrokenBlock + block_env = blocksToBlockEnv broken_blocks + + -- Group the blocks into continuations based on the set of proc-points. + continuations :: [Continuation] + continuations = map (gatherBlocksIntoContinuation proc_points block_env) + (uniqSetToList proc_points) + + -- Select the stack format on entry to each continuation. + -- + -- This is an association list instead of a UniqFM because + -- CLabel's don't have a 'Uniqueable' instance. + formats :: [(CLabel, StackFormat)] + formats = selectStackFormat live continuations + + -- Do the actual CPS transform. + cps_procs :: [CmmTop] + cps_procs = map (continuationToProc formats) continuations + +-------------------------------------------------------------------------------- + +-- The format for the call to a continuation +-- The fst is the arguments that must be passed to the continuation +-- by the continuation's caller. +-- The snd is the live values that must be saved on stack. +-- A Nothing indicates an ignored slot. +-- The head of each list is the stack top or the first parameter. + +-- The format for live values for a particular continuation +-- All on stack for now. +-- Head element is the top of the stack (or just under the header). +-- Nothing means an empty slot. +-- Future possibilities include callee save registers (i.e. passing slots in register) +-- and heap memory (not sure if that's usefull at all though, but it may +-- be worth exploring the design space). + +continuationLabel (Continuation _ _ l _ _) = l +data Continuation = + Continuation + Bool -- True => Function entry, False => Continuation/return point + [CmmStatic] -- Info table, may be empty + CLabel -- Used to generate both info & entry labels + CmmFormals -- Argument locals live on entry (C-- procedure params) + [BrokenBlock] -- Code, may be empty. The first block is + -- the entry point. The order is otherwise initially + -- unimportant, but at some point the code gen will + -- fix the order. + + -- the BlockId of the first block does not give rise + -- to a label. To jump to the first block in a Proc, + -- use the appropriate CLabel. + +-- Describes the layout of a stack frame for a continuation +data StackFormat + = StackFormat + (Maybe CLabel) -- The label occupying the top slot + WordOff -- Total frame size in words + [(CmmReg, WordOff)] -- local reg offsets from stack top + +-- A block can be a continuation of a call +-- A block can be a continuation of another block (w/ or w/o joins) +-- A block can be an entry to a function + +----------------------------------------------------------------------------- + +collectNonProcPointTargets :: + UniqSet BlockId -> BlockEnv BrokenBlock + -> UniqSet BlockId -> BlockId -> UniqSet BlockId +collectNonProcPointTargets proc_points blocks current_targets block = + if sizeUniqSet current_targets == sizeUniqSet new_targets + then current_targets + else foldl (collectNonProcPointTargets proc_points blocks) new_targets targets + where + block' = lookupWithDefaultUFM blocks (panic "TODO") block + targets = + -- Note the subtlety that since the extra branch after a call + -- will always be to a block that is a proc-point, + -- this subtraction will always remove that case + uniqSetToList $ (mkUniqSet $ brokenBlockTargets block') `minusUniqSet` proc_points + -- TODO: remove redundant uniqSetToList + new_targets = current_targets `unionUniqSets` (mkUniqSet targets) + +-- TODO: insert proc point code here +-- * Branches and switches to proc points may cause new blocks to be created +-- (or proc points could leave behind phantom blocks that just jump to them) +-- * Proc points might get some live variables passed as arguments + +gatherBlocksIntoContinuation :: + UniqSet BlockId -> BlockEnv BrokenBlock + -> BlockId -> Continuation +gatherBlocksIntoContinuation proc_points blocks start = + Continuation is_entry info_table clabel params body + where + children = (collectNonProcPointTargets proc_points blocks (unitUniqSet start) start) `delOneFromUniqSet` start + start_block = lookupWithDefaultUFM blocks (panic "TODO") start + children_blocks = map (lookupWithDefaultUFM blocks (panic "TODO")) (uniqSetToList children) + body = start_block : children_blocks + info_table = [] -- TODO + start_block_entry = brokenBlockEntry start_block + is_entry = case start_block_entry of + FunctionEntry _ _ -> True + _ -> False + clabel = case start_block_entry of + FunctionEntry label _ -> label + _ -> mkReturnPtLabel $ getUnique start + params = case start_block_entry of + FunctionEntry _ args -> args + ContinuationEntry args -> args + ControlEntry -> [] -- TODO: it's a proc-point, we could pass lives in parameter registers + +-------------------------------------------------------------------------------- +-- For now just select the continuation orders in the order they are in the set with no gaps + +selectStackFormat :: BlockEnv CmmLive -> [Continuation] -> [(CLabel, StackFormat)] +selectStackFormat live continuations = + map (\c -> (continuationLabel c, selectStackFormat' c)) continuations + where + selectStackFormat' (Continuation True info_table label formals blocks) = + StackFormat (Just label) 0 [] + selectStackFormat' (Continuation False info_table label formals blocks) = + -- TODO: assumes the first block is the entry block + let ident = brokenBlockId $ head blocks -- TODO: CLabel isn't a uniquable, but we need a better way than this + in live_to_format label formals $ lookupWithDefaultUFM live unknown_block ident + + live_to_format :: CLabel -> CmmFormals -> CmmLive -> StackFormat + live_to_format label formals live = + foldl extend_format + (StackFormat (Just label) retAddrSizeW []) + (uniqSetToList (live `minusUniqSet` mkUniqSet (cmmFormalsToLiveLocals formals))) + + extend_format :: StackFormat -> LocalReg -> StackFormat + extend_format (StackFormat label size offsets) reg = + StackFormat label (slot_size reg + size) ((CmmLocal reg, size) : offsets) + + slot_size :: LocalReg -> Int + slot_size reg = ((machRepByteWidth (localRegRep reg) - 1) `div` wORD_SIZE) + 1 + + unknown_block = panic "unknown BlockId in selectStackFormat" + +continuationToProc :: [(CLabel, StackFormat)] -> Continuation -> CmmTop +continuationToProc formats (Continuation is_entry info label formals blocks) = + CmmProc info label formals (map (continuationToProc' label formats) blocks) + where + continuationToProc' :: CLabel -> [(CLabel, StackFormat)] -> BrokenBlock + -> CmmBasicBlock + continuationToProc' curr_ident formats (BrokenBlock ident entry stmts _ exit) = + BasicBlock ident (prefix++stmts++postfix) + where + curr_format = maybe unknown_block id $ lookup curr_ident formats + unknown_block = panic "unknown BlockId in continuationToProc" + prefix = case entry of + ControlEntry -> [] + FunctionEntry _ _ -> [] + ContinuationEntry formals -> + unpack_continuation curr_format + postfix = case exit of + FinalBranch next -> [CmmBranch next] + FinalSwitch expr targets -> [CmmSwitch expr targets] + FinalReturn arguments -> + exit_function curr_format + (CmmLoad (CmmReg spReg) wordRep) + arguments + FinalJump target arguments -> + exit_function curr_format target arguments + FinalCall next (CmmForeignCall target CmmCallConv) + results arguments -> + pack_continuation curr_format cont_format ++ + [CmmJump target arguments] + where + cont_format = maybe unknown_block id $ + lookup (mkReturnPtLabel $ getUnique next) formats + FinalCall next _ results arguments -> panic "unimplemented CmmCall" + +-------------------------------------------------------------------------------- +-- Functions that generate CmmStmt sequences +-- for packing/unpacking continuations +-- and entering/exiting functions + +exit_function :: StackFormat -> CmmExpr -> CmmActuals -> [CmmStmt] +exit_function (StackFormat curr_id curr_frame_size curr_offsets) target arguments + = adjust_spReg ++ jump where + adjust_spReg = + if curr_frame_size == 0 + then [] + else [CmmAssign spReg + (CmmRegOff spReg (curr_frame_size*wORD_SIZE))] + jump = [CmmJump target arguments] + +enter_function :: WordOff -> [CmmStmt] +enter_function max_frame_size + = check_stack_limit where + check_stack_limit = [ + CmmCondBranch + (CmmMachOp (MO_U_Lt $ cmmRegRep spReg) + [CmmRegOff spReg max_frame_size, CmmReg spLimReg]) + gc_block] + gc_block = panic "gc_check not implemented" -- TODO: get stack and heap checks to go to same + +-- TODO: fix branches to proc point (we have to insert a new block to marshel the continuation) +pack_continuation :: StackFormat -> StackFormat -> [CmmStmt] +pack_continuation (StackFormat curr_id curr_frame_size curr_offsets) + (StackFormat cont_id cont_frame_size cont_offsets) + = save_live_values ++ set_stack_header ++ adjust_spReg where + -- TODO: only save variables when actually needed + save_live_values = + [CmmStore + (CmmRegOff + spReg (wORD_SIZE*(curr_frame_size - cont_frame_size + offset))) + (CmmReg reg) + | (reg, offset) <- cont_offsets] + needs_header = + case (curr_id, cont_id) of + (Just x, Just y) -> x /= y + _ -> isJust cont_id + set_stack_header = + if not needs_header + then [] + else [CmmStore (CmmRegOff spReg (wORD_SIZE*(curr_frame_size - cont_frame_size))) continuation_function] + continuation_function = CmmLit $ CmmLabel $ fromJust cont_id + adjust_spReg = + if curr_frame_size == cont_frame_size + then [] + else [CmmAssign spReg (CmmRegOff spReg ((curr_frame_size - cont_frame_size)*wORD_SIZE))] + +-- Lazy adjustment of stack headers assumes all blocks +-- that could branch to eachother (i.e. control blocks) +-- have the same stack format (this causes a problem +-- only for proc-point). +unpack_continuation :: StackFormat -> [CmmStmt] +unpack_continuation (StackFormat curr_id curr_frame_size curr_offsets) + = load_live_values where + -- TODO: only save variables when actually needed + load_live_values = + [CmmAssign + reg + (CmmLoad (CmmRegOff spReg (wORD_SIZE*offset)) (cmmRegRep reg)) + | (reg, offset) <- curr_offsets] +