X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=compiler%2Fcmm%2FCmmCPS.hs;h=be9f474cbeac98de98dab39e86f57fe6c4b20b14;hb=1f46671fe24c7155ee64091b71b77dd66909e7a0;hp=4ec2fc60f15935d29be70ee306d3f850871974af;hpb=d0f6db5b0cf1189d84e292aeca350211f3b810dd;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmCPS.hs b/compiler/cmm/CmmCPS.hs index 4ec2fc6..be9f474 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 +10,40 @@ import Cmm import CmmLint import PprCmm -import Dataflow (mapCmmTop, onBasicBlock, cmmLivenessComment, cmmLiveness) +import CmmLive +import CmmBrokenBlock +import CmmProcPoint +import CmmCallConv +import CmmInfo +import CmmUtils + +import Bitmap +import ClosureInfo +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 + -> [GenCmm CmmStatic CmmInfo CmmStmt] -- ^ Input C-- with Proceedures + -> IO [GenCmm CmmStatic [CmmStatic] CmmStmt] -- ^ Output CPS transformed C-- cmmCPS dflags abstractC = do when (dopt Opt_DoCmmLinting dflags) $ do showPass dflags "CmmLint" @@ -28,9 +52,494 @@ 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 + +stg_gc_gen = mkRtsApFastLabel SLIT("gen_cg_TODO") --panic "Need the label for gc" +make_gc_block block_id fun_label formals srt = BasicBlock block_id stmts + where + stmts = [CmmCall stg_gc_gen_target [] [] srt, + CmmJump fun_expr actuals] + stg_gc_gen_target = + CmmForeignCall (CmmLit (CmmLabel stg_gc_gen)) CmmCallConv + actuals = map (\x -> (CmmReg (CmmLocal x), NoHint)) formals + fun_expr = CmmLit (CmmLabel fun_label) + +force_gc_block old_info block_id fun_label formals blocks = + case old_info of + CmmNonInfo (Just _) -> (old_info, []) + CmmInfo _ (Just _) _ _ -> (old_info, []) + CmmNonInfo Nothing + -> (CmmNonInfo (Just block_id), + [make_gc_block block_id fun_label formals NoC_SRT]) + CmmInfo prof Nothing type_tag type_info + -> (CmmInfo prof (Just block_id) type_tag type_info, + [make_gc_block block_id fun_label formals srt]) + where + srt = case type_info of + ConstrInfo _ _ _ -> NoC_SRT + FunInfo _ srt' _ _ _ _ -> srt' + ThunkInfo _ srt' -> srt' + ThunkSelectorInfo _ srt' -> srt' + ContInfo _ srt' -> srt' + +----------------------------------------------------------------------------- +-- |CPS a single CmmTop (proceedure) +-- Only 'CmmProc' are transformed 'CmmData' will be left alone. +----------------------------------------------------------------------------- + +cpsProc :: UniqSupply + -> GenCmmTop CmmStatic CmmInfo CmmStmt -- ^Input proceedure + -> [GenCmmTop CmmStatic [CmmStatic] CmmStmt] -- ^Output proceedure and continuations +cpsProc uniqSupply (CmmData sec dat) = [CmmData sec dat] +cpsProc uniqSupply (CmmProc info ident params blocks) = info_procs + where + uniques :: [[Unique]] + uniques = map uniqsFromSupply $ listSplitUniqSupply uniqSupply + (gc_unique:info_uniques):block_uniques = uniques + + -- Ensure that + forced_gc :: (CmmInfo, [CmmBasicBlock]) + forced_gc = force_gc_block info (BlockId gc_unique) ident params blocks + + forced_info = fst forced_gc + forced_blocks = blocks ++ snd forced_gc + forced_gc_id = case forced_info of + CmmNonInfo (Just x) -> x + CmmInfo _ (Just x) _ _ -> x + + -- 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 block_uniques forced_blocks + (FunctionEntry forced_info 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 (Either C_SRT CmmInfo)] + continuations = zipWith + (gatherBlocksIntoContinuation proc_points block_env) + (uniqSetToList proc_points) + (Just forced_gc_id : repeat Nothing) + + -- Select the stack format on entry to each continuation. + -- Return the max stack offset and an association list + -- + -- This is an association list instead of a UniqFM because + -- CLabel's don't have a 'Uniqueable' instance. + formats :: [(CLabel, (Maybe CLabel, [Maybe LocalReg]))] + formats = selectStackFormat live continuations + + -- Do a little meta-processing on the stack formats such as + -- getting the individual frame sizes and the maximum frame size + formats' :: (WordOff, [(CLabel, StackFormat)]) + formats' = processFormats formats + + -- TODO FIXME NOW: calculate a real max stack (including function call args) + -- TODO: from the maximum frame size get the maximum stack size. + -- The difference is due to the size taken by function calls. + + -- Update the info table data on the continuations with + -- the selected stack formats. + continuations' :: [Continuation CmmInfo] + continuations' = map (applyStackFormat (snd formats')) continuations + + -- Do the actual CPS transform. + cps_procs :: [CmmTop] + cps_procs = map (continuationToProc formats') continuations' + + -- Convert the info tables from CmmInfo to [CmmStatic] + -- We might want to put this in another pass eventually + info_procs :: [RawCmmTop] + info_procs = concat (zipWith mkInfoTable info_uniques cps_procs) + +-------------------------------------------------------------------------------- + +-- 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 info = + Continuation + info --(Either C_SRT CmmInfo) -- Left <=> Continuation created by the CPS + -- Right <=> Function or Proc point + 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. + +data StackFormat + = StackFormat { + stack_label :: Maybe CLabel, -- The label occupying the top slot + stack_frame_size :: WordOff, -- Total frame size in words (not including arguments) + stack_live :: [Maybe LocalReg] -- 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 new_blocks = + if sizeUniqSet current_targets == sizeUniqSet new_targets + then current_targets + else foldl + (collectNonProcPointTargets proc_points blocks) + new_targets + (map (:[]) targets) + where + blocks' = map (lookupWithDefaultUFM blocks (panic "TODO")) new_blocks + 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 $ (unionManyUniqSets $ map (mkUniqSet . brokenBlockTargets) blocks') + `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 -> Maybe BlockId -> Continuation (Either C_SRT CmmInfo) +gatherBlocksIntoContinuation proc_points blocks start gc = + Continuation info_table clabel params body + where + start_and_gc = start : maybeToList gc + children = (collectNonProcPointTargets proc_points blocks (mkUniqSet start_and_gc) start_and_gc) `minusUniqSet` (mkUniqSet start_and_gc) + start_block = lookupWithDefaultUFM blocks (panic "TODO") start + gc_block = map (lookupWithDefaultUFM blocks (panic "TODO)")) (maybeToList gc) + children_blocks = map (lookupWithDefaultUFM blocks (panic "TODO")) (uniqSetToList children) + body = start_block : gc_block ++ children_blocks + + -- We can't properly annotate the continuation's stack parameters + -- at this point because this is before stack selection + -- but we want to keep the C_SRT around so we use 'Either'. + info_table = case start_block_entry of + FunctionEntry info _ _ -> Right info + ContinuationEntry _ srt -> Left srt + ControlEntry -> Right (CmmNonInfo Nothing) + + start_block_entry = brokenBlockEntry start_block + 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 (Either C_SRT CmmInfo)] + -> [(CLabel, (Maybe CLabel, [Maybe LocalReg]))] +selectStackFormat live continuations = + map (\c -> (continuationLabel c, selectStackFormat' c)) continuations + where + selectStackFormat' (Continuation + (Right (CmmInfo _ _ _ (ContInfo format srt))) + label _ _) = (Just label, format) + selectStackFormat' (Continuation (Right _) _ _ _) = (Nothing, []) + selectStackFormat' (Continuation (Left srt) label _ 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 (Just label, + map Just $ uniqSetToList $ + lookupWithDefaultUFM live unknown_block ident) + + unknown_block = panic "unknown BlockId in selectStackFormat" + +processFormats :: [(CLabel, (Maybe CLabel, [Maybe LocalReg]))] + -> (WordOff, [(CLabel, StackFormat)]) +processFormats formats = (max_size, formats') + where + max_size = foldl max 0 (map (stack_frame_size . snd) formats') + formats' = map make_format formats + make_format (label, format) = + (label, + StackFormat { + stack_label = fst format, + stack_frame_size = stack_size (snd format) + + if isJust (fst format) + then label_size + else 0, + stack_live = snd format }) + + -- TODO: get rid of "+ 1" etc. + label_size = 1 :: WordOff + + stack_size [] = 0 + stack_size (Nothing:formats) = 1 + stack_size formats -- one dead word + stack_size (Just reg:formats) = width + stack_size formats + where + width = machRepByteWidth (localRegRep reg) `quot` wORD_SIZE + -- TODO: it would be better if we had a machRepWordWidth + +----------------------------------------------------------------------------- +applyStackFormat :: [(CLabel, StackFormat)] + -> Continuation (Either C_SRT CmmInfo) + -> Continuation CmmInfo + +-- User written continuations +applyStackFormat formats (Continuation + (Right (CmmInfo prof gc tag (ContInfo _ srt))) + label formals blocks) = + Continuation (CmmInfo prof gc tag (ContInfo format srt)) + label formals blocks + where + format = stack_live $ maybe unknown_block id $ lookup label formats + unknown_block = panic "unknown BlockId in applyStackFormat" + +-- User written non-continuation code +applyStackFormat formats (Continuation (Right info) label formals blocks) = + Continuation info label formals blocks + +-- CPS generated continuations +applyStackFormat formats (Continuation (Left srt) label formals blocks) = + Continuation (CmmInfo prof gc tag (ContInfo (stack_live $ format) srt)) + label formals blocks + where + gc = Nothing -- Generated continuations never need a stack check + -- TODO prof: this is the same as the current implementation + -- but I think it could be improved + prof = ProfilingInfo zeroCLit zeroCLit + tag = if stack_frame_size format > mAX_SMALL_BITMAP_SIZE + then rET_BIG + else rET_SMALL + format = maybe unknown_block id $ lookup label formats + unknown_block = panic "unknown BlockId in applyStackFormat" + +----------------------------------------------------------------------------- +continuationToProc :: (WordOff, [(CLabel, StackFormat)]) + -> Continuation CmmInfo + -> CmmTop +continuationToProc (max_stack, formats) + (Continuation info label formals blocks) = + CmmProc info label formals (map continuationToProc' blocks) + where + curr_format = maybe unknown_block id $ lookup label formats + unknown_block = panic "unknown BlockId in continuationToProc" + + continuationToProc' :: BrokenBlock -> CmmBasicBlock + continuationToProc' (BrokenBlock ident entry stmts _ exit) = + BasicBlock ident (prefix++stmts++postfix) + where + prefix = case entry of + ControlEntry -> [] + FunctionEntry (CmmInfo _ (Just gc_block) _ _) _ formals -> + gc_stack_check gc_block max_stack ++ + function_entry formals curr_format + FunctionEntry (CmmInfo _ Nothing _ _) _ formals -> + panic "continuationToProc: missing GC block" + FunctionEntry (CmmNonInfo (Just gc_block)) _ formals -> + gc_stack_check gc_block max_stack ++ + function_entry formals curr_format + FunctionEntry (CmmNonInfo Nothing) _ formals -> + panic "continuationToProc: missing non-info GC block" + ContinuationEntry formals _ -> + function_entry formals curr_format + postfix = case exit of + FinalBranch next -> [CmmBranch next] + FinalSwitch expr targets -> [CmmSwitch expr targets] + FinalReturn arguments -> + tail_call (stack_frame_size curr_format) + (CmmLoad (CmmReg spReg) wordRep) + arguments + FinalJump target arguments -> + tail_call (stack_frame_size curr_format) target arguments + FinalCall next (CmmForeignCall target CmmCallConv) + results arguments -> + pack_continuation curr_format cont_format ++ + tail_call (stack_frame_size curr_format - stack_frame_size cont_format) + 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 + +tail_call :: WordOff -> CmmExpr -> CmmActuals -> [CmmStmt] +tail_call spRel target arguments + = store_arguments ++ adjust_spReg ++ jump where + store_arguments = + [stack_put spRel expr offset + | ((expr, _), StackParam offset) <- argument_formats] ++ + [global_put expr global + | ((expr, _), RegisterParam global) <- argument_formats] + adjust_spReg = + if spRel == 0 + then [] + else [CmmAssign spReg (CmmRegOff spReg (spRel*wORD_SIZE))] + jump = [CmmJump target arguments] + + argument_formats = assignArguments (cmmExprRep . fst) arguments + +gc_stack_check :: BlockId -> WordOff -> [CmmStmt] +gc_stack_check gc_block max_frame_size + = check_stack_limit where + check_stack_limit = [ + CmmCondBranch + (CmmMachOp (MO_U_Lt $ cmmRegRep spReg) + [CmmRegOff spReg (-max_frame_size*wORD_SIZE), + CmmReg spLimReg]) + gc_block] + +-- 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 _) + (StackFormat cont_id cont_frame_size live_regs) + = store_live_values ++ set_stack_header where + -- TODO: only save variables when actually needed + -- (may be handled by latter pass) + store_live_values = + [stack_put spRel (CmmReg (CmmLocal reg)) offset + | (reg, offset) <- cont_offsets] + set_stack_header = + if needs_header_set + then [stack_put spRel continuation_function 0] + else [] + + -- TODO: factor with function_entry and CmmInfo.hs(?) + cont_offsets = mkOffsets label_size live_regs + + label_size = 1 :: WordOff + + mkOffsets size [] = [] + mkOffsets size (Nothing:regs) = mkOffsets (size+1) regs + mkOffsets size (Just reg:regs) = (reg, size):mkOffsets (size + width) regs + where + width = machRepByteWidth (localRegRep reg) `quot` wORD_SIZE + -- TODO: it would be better if we had a machRepWordWidth + + spRel = curr_frame_size - cont_frame_size + continuation_function = CmmLit $ CmmLabel $ fromJust cont_id + needs_header_set = + case (curr_id, cont_id) of + (Just x, Just y) -> x /= y + _ -> isJust cont_id + +-- 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). +function_entry :: CmmFormals -> StackFormat -> [CmmStmt] +function_entry formals (StackFormat _ _ live_regs) + = load_live_values ++ load_args where + -- TODO: only save variables when actually needed + -- (may be handled by latter pass) + load_live_values = + [stack_get 0 reg offset + | (reg, offset) <- curr_offsets] + load_args = + [stack_get 0 reg offset + | (reg, StackParam offset) <- argument_formats] ++ + [global_get reg global + | (reg, RegisterParam global) <- argument_formats] + + argument_formats = assignArguments (localRegRep) formals + + -- TODO: eliminate copy/paste with pack_continuation + curr_offsets = mkOffsets label_size live_regs + + label_size = 1 :: WordOff + + mkOffsets size [] = [] + mkOffsets size (Nothing:regs) = mkOffsets (size+1) regs + mkOffsets size (Just reg:regs) = (reg, size):mkOffsets (size + width) regs + where + width = machRepByteWidth (localRegRep reg) `quot` wORD_SIZE + -- TODO: it would be better if we had a machRepWordWidth + +----------------------------------------------------------------------------- +-- Section: Stack and argument register puts and gets +----------------------------------------------------------------------------- +-- TODO: document + +-- |Construct a 'CmmStmt' that will save a value on the stack +stack_put :: WordOff -- ^ Offset from the real 'Sp' that 'offset' + -- is relative to (added to offset) + -> CmmExpr -- ^ What to store onto the stack + -> WordOff -- ^ Where on the stack to store it + -- (positive <=> higher addresses) + -> CmmStmt +stack_put spRel expr offset = + CmmStore (CmmRegOff spReg (wORD_SIZE*(spRel + offset))) expr + +-------------------------------- +-- |Construct a +stack_get :: WordOff + -> LocalReg + -> WordOff + -> CmmStmt +stack_get spRel reg offset = + CmmAssign (CmmLocal reg) + (CmmLoad (CmmRegOff spReg (wORD_SIZE*(spRel + offset))) + (localRegRep reg)) +global_put :: CmmExpr -> GlobalReg -> CmmStmt +global_put expr global = CmmAssign (CmmGlobal global) expr +global_get :: LocalReg -> GlobalReg -> CmmStmt +global_get reg global = CmmAssign (CmmLocal reg) (CmmReg (CmmGlobal global)) +