X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=compiler%2Fcmm%2FCmmCPS.hs;h=2726ef83041d3e84bef53fc7fe54a107bba3499c;hb=bdfa9495e95ba5701f27711b27d8e22ae7bb8335;hp=e708ebbdad36e0f9cb92316ed54c67a8333142bb;hpb=4343368be10030e61acaa8fde2cedbb5fb26918c;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmCPS.hs b/compiler/cmm/CmmCPS.hs index e708ebb..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" @@ -6,11 +10,17 @@ import Cmm import CmmLint import PprCmm -import Dataflow (cmmLivenessComment, cmmLiveness, CmmLive) +import Dataflow +import CmmLive +import CmmBrokenBlock +import CmmProcPoint +import CmmCallConv import MachOp import ForeignCall import CLabel +import SMRep +import Constants import DynFlags import ErrUtils @@ -23,36 +33,91 @@ import Unique import Monad import IO +import Data.List + +----------------------------------------------------------------------------- +-- |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" + case firstJust $ map cmmLint abstractC of + Just err -> do printDump err + ghcExit dflags 1 + Nothing -> return () + showPass dflags "CPS" --------------------------------------------------------------------------------- --- Monad for the CPSer --- Contains: --- * State for the uniqSupply - -data CPSState = CPSState { cps_uniqs :: UniqSupply } - -data CPS a = CPS { runCPS :: CPSState -> (CPSState, a) } + -- TODO: more lint checking + -- check for use of branches to non-existant blocks + -- check for use of Sp, SpLim, R1, R2, etc. -instance Monad CPS where - return a = CPS $ \s -> (s, a) - (CPS m) >>= f = CPS $ \s -> - let (s', m') = m s - in runCPS (f m') s' + 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 --------------------------------------------------------------------------------- --- Utility functions + dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC) -getState = CPS $ \s -> (s, s) -putState s = CPS $ \_ -> (s, ()) + -- TODO: add option to dump Cmm to file -newLabelCPS = do - state <- getState - let (us1, us2) = splitUniqSupply (cps_uniqs state) - putState $ state { cps_uniqs = us1 } - return $ BlockId (uniqFromSupply us2) + return continuationC -mapMCmmTop :: (Monad m) => (CmmTop -> m [CmmTop]) -> Cmm -> m Cmm -mapMCmmTop f (Cmm xs) = liftM Cmm $ liftM concat $ mapM f xs +----------------------------------------------------------------------------- +-- |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 -------------------------------------------------------------------------------- @@ -71,141 +136,205 @@ mapMCmmTop f (Cmm xs) = liftM Cmm $ liftM concat $ mapM f xs -- and heap memory (not sure if that's usefull at all though, but it may -- be worth exploring the design space). -data CPSBlockInfo - = ControlBlock -- Consider whether a proc-point might want arguments on stack - | ContinuationBlock [(CmmReg,MachHint)] {- params -} - -type ContinuationFormat = [Maybe LocalReg] -- TODO: consider params as part of format +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 -type CmmParam = [(CmmReg,MachHint)] +----------------------------------------------------------------------------- + +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 -selectContinuationFormat :: UniqFM {-BlockId-} CmmParam -> UniqFM {-BlockId-} CmmLive -> UniqFM {-BlockId-} ContinuationFormat -selectContinuationFormat param live = mapUFM (map Just . uniqSetToList) live - -transformReturn block_infos formats (BasicBlock ident stmts) = - case last $ init stmts of - CmmReturn arguments -> - BasicBlock ident $ (init $ init stmts) ++ - [CmmJump (CmmReg spReg) arguments] - -- TODO: tail calls - -- TODO: return direct at the end of a block - _ -> BasicBlock ident stmts - -destructContinuation :: UniqFM {-BlockId-} CPSBlockInfo -> UniqFM {-BlockId-} ContinuationFormat -> CmmBasicBlock -> CmmBasicBlock -destructContinuation block_infos formats (BasicBlock ident stmts) = - case info of - ControlBlock -> BasicBlock ident stmts - ContinuationBlock _ -> BasicBlock ident (unpack_continuation ++ stmts) - where - info = lookupWithDefaultUFM block_infos (panic $ "info: unknown block " ++ (showSDoc $ ppr $ getUnique ident)) ident - format = lookupWithDefaultUFM formats (panic $ "format: unknown block " ++ (showSDoc $ ppr $ getUnique ident)) ident - unpack_continuation = CmmAssign spReg (CmmRegOff spReg frame_size) : - [CmmAssign (CmmLocal reg) (CmmLoad (CmmRegOff spReg (i*stack_slot_size)) (localRegRep reg)) - | (i, Just reg) <- zip [1..] format] - frame_size = stack_header_size + stack_slot_size * (length format) - stack_header_size = stack_slot_size -- TODO: check if this could be different than stack_slot_size - stack_slot_size = 4 -- TODO: find actual variables to be used instead of this - -constructContinuation :: UniqFM {-BlockId-} CPSBlockInfo -> UniqFM {-BlockId-} ContinuationFormat -> CmmBasicBlock -> CmmBasicBlock -constructContinuation block_infos formats (BasicBlock ident stmts) = - case last $ init stmts of - -- TODO: global_saves - --CmmCall (CmmForeignCall target CmmCallConv) results arguments (Just []) -> --TODO: handle globals - CmmCall (CmmForeignCall target CmmCallConv) results arguments _ -> - BasicBlock ident $ - init (init stmts) ++ - pack_continuation ++ - [CmmJump target arguments] - CmmCall target results arguments _ -> panic "unimplemented CmmCall" - _ -> BasicBlock ident $ (init stmts) ++ build_block_branch - where - info = lookupWithDefaultUFM block_infos (panic $ "info: unknown block " ++ (showSDoc $ ppr $ getUnique next_block)) next_block - format = lookupWithDefaultUFM formats (panic $ "format: unknown block " ++ (showSDoc $ ppr $ getUnique next_block)) next_block - next_block = case last stmts of - CmmBranch next -> next - -- TODO: blocks with jump at end - -- TODO: blocks with return at end - _ -> panic "basic block without a branch at the end (unimplemented)" - next_block_as_proc_expr = CmmLit $ CmmLabel $ mkReturnPtLabel $ getUnique next_block - pack_continuation = CmmAssign spReg (CmmRegOff spReg (-frame_size)) : - CmmStore (CmmReg spReg) next_block_as_proc_expr : - [CmmStore (CmmRegOff spReg (i*stack_slot_size)) (CmmReg $ CmmLocal reg) - | (i, Just reg) <- zip [1..] format] - frame_size = stack_header_size + stack_slot_size * (length format) - stack_header_size = stack_slot_size -- TODO: check if this could be different than stack_slot_size (e.g. fixedHdrSize depends on PAR and GRAN) - stack_slot_size = 4 -- TODO: find actual variables to be used instead of this (e.g. cgRepSizeW) - block_needs_call = True -- TODO: use a table (i.e. proc-point) - build_block_branch = - if block_needs_call - then [CmmJump next_block_as_proc_expr [] {- TODO: pass live -}] {- NOTE: a block can never be both a continuation and a controll block -} - else [CmmBranch next_block] - --- TODO: TBD when to adjust the stack - -cpsProc :: CmmTop -> CPS [CmmTop] -cpsProc x@(CmmData _ _) = return [x] -cpsProc x@(CmmProc info_table ident params blocks) = do - broken_blocks <- liftM concat $ mapM breakBlock blocks - let live = cmmLiveness (map snd broken_blocks) - let blocks_with_live = map (cmmLivenessComment live . snd) broken_blocks - let formats = selectContinuationFormat (undefined {-TODO-}) live - let block_infos = listToUFM $ map (\(info, block) -> (blockId block, info)) broken_blocks - let blocks_with_live' = map (constructContinuation block_infos formats) blocks_with_live - let blocks_with_live'' = map (destructContinuation block_infos formats) blocks_with_live' - let blocks_with_live''' = map (transformReturn block_infos formats) blocks_with_live'' - - return $ [CmmProc info_table ident params blocks_with_live'''] --------------------------------------------------------------------------------- --- Takes a basic block and returns a list of basic blocks that --- each have at most 1 CmmCall in them which must occur at the end. --- Also returns with each basic block, the variables that will --- be arguments to the continuation of the block once the call (if any) returns. - -cmmBlockifyCalls :: [CmmBasicBlock] -> CPS [(CPSBlockInfo, CmmBasicBlock)] -cmmBlockifyCalls blocks = liftM concat $ mapM breakBlock blocks - --- [(CmmReg,MachHint)] is the results from the previous block that are expected as parameters ---breakBlock :: CmmBasicBlock -> CPS [(Maybe BlockId, CmmBasicBlock)] -breakBlock :: CmmBasicBlock -> CPS [(CPSBlockInfo, CmmBasicBlock)] -breakBlock (BasicBlock ident stmts) = breakBlock' ident ControlBlock [] stmts - -breakBlock' current_id block_info accum_stmts [] = - return [(block_info, BasicBlock current_id accum_stmts)] --- TODO: notice a call just before a branch, jump, call, etc. -breakBlock' current_id block_info accum_stmts (stmt@(CmmCall _ results _ _):stmts) = do - new_id <- newLabelCPS - let new_block = (block_info, BasicBlock current_id (accum_stmts ++ [stmt, CmmBranch new_id])) - rest <- breakBlock' new_id (ContinuationBlock results) [] stmts - return $ (new_block:rest) -breakBlock' current_id arguments accum_stmts (stmt:stmts) = - breakBlock' current_id arguments (accum_stmts ++ [stmt]) stmts +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" -------------------------------------------------------------------------------- -cmmCPS :: DynFlags - -> [Cmm] -- C-- with Proceedures - -> IO [Cmm] -- Output: CPS transformed C-- - -cmmCPS dflags abstractC = do - when (dopt Opt_DoCmmLinting dflags) $ - do showPass dflags "CmmLint" - case firstJust $ map cmmLint abstractC of - Just err -> do printDump err - ghcExit dflags 1 - Nothing -> return () - showPass dflags "CPS" - -- TODO: check for use of branches to non-existant blocks - -- TODO: check for use of Sp, SpLim, R1, R2, etc. - -- continuationC <- return abstractC - -- TODO: find out if it is valid to create a new unique source like this - uniqSupply <- mkSplitUniqSupply 'p' - let (_, continuationC) = runCPS (mapM (mapMCmmTop cpsProc) abstractC) (CPSState uniqSupply) +-- 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] - dumpIfSet_dyn dflags Opt_D_dump_cps_cmm "CPS Cmm" (pprCmms continuationC) - -- TODO: add option to dump Cmm to file - return continuationC