X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmSpillReload.hs;h=dcbde33722268fd32395ded9e118711ca049bdb7;hb=c62b824e9e8808eb3845ddb1614494b0575eaafd;hp=d8108e94ed41b2607a9cefde782ad5eb79f137e8;hpb=684fde094dc5b064b49dbef191ca07cb9a018e45;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index d8108e9..dcbde33 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -1,11 +1,9 @@ module CmmSpillReload - ( ExtendWithSpills(..) - , DualLive(..) - , dualLiveLattice, dualLiveness - , insertSpillsAndReloads --- XXX todo check live-in at entry against formals + ( DualLive(..) + , dualLiveLattice, dualLiveTransfers, dualLiveness + --, insertSpillsAndReloads --- XXX todo check live-in at entry against formals , dualLivenessWithInsertion - , spillAndReloadComments , availRegsLattice , cmmAvailableReloads @@ -14,18 +12,19 @@ module CmmSpillReload ) where +import BlockId import CmmExpr import CmmTx import CmmLiveZ import DFMonad import MkZipCfg +import OptimizationFuel import PprCmm() import ZipCfg import ZipCfgCmmRep import ZipDataflow -import FastString -import Maybes +import Monad import Outputable hiding (empty) import qualified Outputable as PP import Panic @@ -38,17 +37,10 @@ import Prelude hiding (zip) -- establish the invariant that at a call (or at any proc point with -- an established protocol) all live variables not expected in -- registers are sitting on the stack. We use a backward analysis to --- insert spills and reloads. It should some day be followed by a +-- insert spills and reloads. It should be followed by a -- forward transformation to sink reloads as deeply as possible, so as -- to reduce register pressure. -data ExtendWithSpills m - = NotSpillOrReload m - | Spill RegSet - | Reload RegSet - -type M = ExtendWithSpills Middle - -- A variable can be expected to be live in a register, live on the -- stack, or both. This analysis ensures that spills and reloads are -- inserted as needed to make sure that every live variable needed @@ -67,9 +59,9 @@ dualUnionList ls = DualLive ss rs where ss = unionManyUniqSets $ map on_stack ls rs = unionManyUniqSets $ map in_regs ls -_changeStack, changeRegs :: (RegSet -> RegSet) -> DualLive -> DualLive -_changeStack f live = live { on_stack = f (on_stack live) } -changeRegs f live = live { in_regs = f (in_regs live) } +changeStack, changeRegs :: (RegSet -> RegSet) -> DualLive -> DualLive +changeStack f live = live { on_stack = f (on_stack live) } +changeRegs f live = live { in_regs = f (in_regs live) } dualLiveLattice :: DataflowLattice DualLive @@ -82,114 +74,112 @@ dualLiveLattice = return $ DualLive stack regs add1 = fact_add_to liveLattice -dualLivenessWithInsertion :: BPass M Last DualLive -dualLivenessWithInsertion = a_ft_b_unlimited dualLiveness insertSpillsAndReloads +type LiveReloadFix a = FuelMonad (BackwardFixedPoint Middle Last DualLive a) -dualLiveness :: BAnalysis M Last DualLive -dualLiveness = BComp "dual liveness" exit last middle first - where exit = empty - last = lastDualLiveness - middle = middleDualLiveness - first live _id = live +dualLivenessWithInsertion :: BlockSet -> (LGraph Middle Last) -> FuelMonad (LGraph Middle Last) +dualLivenessWithInsertion procPoints g@(LGraph entry _ _) = + liftM zdfFpContents $ (res :: LiveReloadFix (LGraph Middle Last)) + where res = zdfBRewriteFromL RewriteDeep emptyBlockEnv "dual liveness with insertion" + dualLiveLattice (dualLiveTransfers entry procPoints) + (insertSpillAndReloadRewrites entry procPoints) empty g empty = fact_bot dualLiveLattice - -- ^ could take a proc-point set and choose to spill here, - -- but it's probably better to run this pass, choose - -- proc-point protocols, insert more CopyIn nodes, and run - -- this pass again - -middleDualLiveness :: DualLive -> M -> DualLive -middleDualLiveness live (Spill regs) = live' - -- live-in on-stack requirements are satisfied; - -- live-out in-regs obligations are created - where live' = DualLive { on_stack = on_stack live `minusRegSet` regs - , in_regs = in_regs live `plusRegSet` regs } - -middleDualLiveness live (Reload regs) = live' - -- live-in in-regs requirements are satisfied; - -- live-out on-stack obligations are created - where live' = DualLive { on_stack = on_stack live `plusRegSet` regs - , in_regs = in_regs live `minusRegSet` regs } +dualLiveness :: BlockSet -> LGraph Middle Last -> FuelMonad (BlockEnv DualLive) +dualLiveness procPoints g@(LGraph entry _ _) = + liftM zdfFpFacts $ (res :: LiveReloadFix ()) + where res = zdfSolveFromL emptyBlockEnv "dual liveness" dualLiveLattice + (dualLiveTransfers entry procPoints) empty g + empty = fact_bot dualLiveLattice -middleDualLiveness live (NotSpillOrReload m) = changeRegs (middleLiveness m) live +dualLiveTransfers :: BlockId -> BlockSet -> BackwardTransfers Middle Last DualLive +dualLiveTransfers entry procPoints = BackwardTransfers first middle last + where last = lastDualLiveness + middle = middleDualLiveness + first live id = check live id $ -- live at procPoint => spill + if id /= entry && elemBlockSet id procPoints then + DualLive { on_stack = on_stack live `plusRegSet` in_regs live + , in_regs = emptyRegSet } + else live + check live id x = if id == entry then noLiveOnEntry id (in_regs live) x else x + +middleDualLiveness :: DualLive -> Middle -> DualLive +middleDualLiveness live m = + changeStack updSlots $ changeRegs (middleLiveness m) (changeRegs regs_in live) + where regs_in live = case m of MidForeignCall {} -> emptyRegSet + _ -> live + updSlots live = foldSlotsUsed reload (foldSlotsDefd spill live m) m + spill live s@(RegSlot r, _, _) = check s $ deleteFromRegSet live r + spill live _ = live + reload live s@(RegSlot r, _, _) = check s $ extendRegSet live r + reload live _ = live + check (RegSlot (LocalReg _ ty), o, w) x + | o == w && w == widthInBytes (typeWidth ty) = x + check _ _ = panic "middleDualLiveness unsupported: slices" lastDualLiveness :: (BlockId -> DualLive) -> Last -> DualLive lastDualLiveness env l = last l - where last (LastReturn) = empty - last (LastJump e) = changeRegs (gen e) empty - last (LastBranch id) = env id - last (LastCall tgt Nothing) = changeRegs (gen tgt) empty - last (LastCall tgt (Just k)) = - -- nothing can be live in registers at this point - let live = env k in - if isEmptyUniqSet (in_regs live) then - DualLive (on_stack live) (gen tgt emptyRegSet) - else - panic "live values in registers at call continuation" - last (LastCondBranch e t f) = changeRegs (gen e) $ dualUnion (env t) (env f) - last (LastSwitch e tbl) = changeRegs (gen e) $ dualUnionList $ + where last (LastBranch id) = env id + last l@(LastCall tgt Nothing _ _) = changeRegs (gen l . kill l) empty + last l@(LastCall tgt (Just k) _ _) = + -- nothing can be live in registers at this point, unless safe foreign call + let live = env k + live_in = DualLive (on_stack live) (gen l emptyRegSet) + in if isEmptyUniqSet (in_regs live) then live_in + else pprTrace "Offending party:" (ppr k <+> ppr live) $ + panic "live values in registers at call continuation" + last l@(LastCondBranch e t f) = + changeRegs (gen l . kill l) $ dualUnion (env t) (env f) + last l@(LastSwitch e tbl) = changeRegs (gen l . kill l) $ dualUnionList $ map env (catMaybes tbl) empty = fact_bot dualLiveLattice -gen, kill :: UserOfLocalRegs a => a -> RegSet -> RegSet -gen a live = foldRegsUsed extendRegSet live a -kill a live = foldRegsUsed delOneFromUniqSet live a - -insertSpillsAndReloads :: BFunctionalTransformation M Last DualLive -insertSpillsAndReloads = BComp "CPS spiller" exit last middle first - where exit = Nothing - last = \_ _ -> Nothing - middle = middleInsertSpillsAndReloads - first _ _ = Nothing - -- ^ could take a proc-point set and choose to spill here, - -- but it's probably better to run this pass, choose - -- proc-point protocols, insert more CopyIn nodes, and run - -- this pass again - - -middleInsertSpillsAndReloads :: DualLive -> M -> Maybe (Graph M Last) -middleInsertSpillsAndReloads _ (Spill _) = Nothing -middleInsertSpillsAndReloads _ (Reload _) = Nothing -middleInsertSpillsAndReloads live (NotSpillOrReload m) = middle m - where middle (MidAssign (CmmLocal reg') _) = - if reg' `elemRegSet` on_stack live then -- must spill - my_trace "Spilling" (f4sep [text "spill" <+> ppr reg', - text "after", ppr m]) $ - Just $ graphOfMiddles [NotSpillOrReload m, Spill $ mkRegSet [reg']] - else - Nothing - middle (CopyIn _ formals _) = - -- only 'formals' can be in regs at this point - let regs' = kill formals (in_regs live) -- live in regs; must reload - is_stack_var r = elemRegSet r (on_stack live) - needs_spilling = -- a formal that is expected on the stack; must spill - foldRegsUsed (\rs r -> if is_stack_var r then extendRegSet rs r - else rs) emptyRegSet formals - in if isEmptyUniqSet regs' && isEmptyUniqSet needs_spilling then - Nothing - else - let reload = if isEmptyUniqSet regs' then [] - else [Reload regs'] - spill_reload = if isEmptyUniqSet needs_spilling then reload - else Spill needs_spilling : reload - middles = NotSpillOrReload m : spill_reload - in - my_trace "At CopyIn" (f4sep [text "Triggered by ", ppr live, - ppr (Reload regs' :: M), - ppr (Spill needs_spilling :: M), - text "after", ppr m]) $ - Just $ graphOfMiddles middles +gen :: UserOfLocalRegs a => a -> RegSet -> RegSet +gen a live = foldRegsUsed extendRegSet live a +kill :: DefinerOfLocalRegs a => a -> RegSet -> RegSet +kill a live = foldRegsDefd deleteFromRegSet live a + +insertSpillAndReloadRewrites :: + BlockId -> BlockSet -> BackwardRewrites Middle Last DualLive +insertSpillAndReloadRewrites entry procPoints = + BackwardRewrites first middle last exit + where middle = middleInsertSpillsAndReloads + last _ _ = Nothing + exit = Nothing + first live id = + if id /= entry && elemBlockSet id procPoints then + case map reload (uniqSetToList (in_regs live)) of + [] -> Nothing + is -> Just (mkMiddles is) + else Nothing + +middleInsertSpillsAndReloads :: DualLive -> Middle -> Maybe (AGraph Middle Last) +middleInsertSpillsAndReloads live m = middle m + where middle (MidAssign (CmmLocal reg) (CmmLoad (CmmStackSlot (RegSlot reg') _) _)) + | reg == reg' = Nothing + middle (MidAssign (CmmLocal reg) _) = + if reg `elemRegSet` on_stack live then -- must spill + my_trace "Spilling" (f4sep [text "spill" <+> ppr reg, + text "after", ppr m]) $ + Just $ mkMiddles $ [m, spill reg] + else Nothing + middle (MidForeignCall _ _ fs _) = + case map spill (filter (flip elemRegSet (on_stack live)) fs) ++ + map reload (uniqSetToList (kill fs (in_regs live))) of + [] -> Nothing + reloads -> Just (mkMiddles (m : reloads)) middle _ = Nothing --- | For conversion back to vanilla C-- -spillAndReloadComments :: M -> Middle -spillAndReloadComments (NotSpillOrReload m) = m -spillAndReloadComments (Spill regs) = show_regs "Spill" regs -spillAndReloadComments (Reload regs) = show_regs "Reload" regs +-- Generating spill and reload code +regSlot :: LocalReg -> CmmExpr +regSlot r = CmmStackSlot (RegSlot r) (widthInBytes $ typeWidth $ localRegType r) -show_regs :: String -> RegSet -> Middle -show_regs s regs = MidComment $ mkFastString $ showSDoc $ ppr_regs s regs +spill, reload :: LocalReg -> Middle +spill r = MidStore (regSlot r) (CmmReg $ CmmLocal r) +reload r = MidAssign (CmmLocal r) (CmmLoad (regSlot r) $ localRegType r) +reloadTail :: RegSet -> ZTail Middle Last -> ZTail Middle Last +reloadTail regset t = foldl rel t $ uniqSetToList regset + where rel t r = ZTail (reload r) t ---------------------------------------------------------------- --- sinking reloads @@ -205,7 +195,8 @@ data AvailRegs = UniverseMinus RegSet availRegsLattice :: DataflowLattice AvailRegs -availRegsLattice = DataflowLattice "register gotten from reloads" empty add True +availRegsLattice = DataflowLattice "register gotten from reloads" empty add False + -- last True <==> debugging on where empty = UniverseMinus emptyRegSet -- | compute in the Tx monad to track whether anything has changed add new old = @@ -225,9 +216,9 @@ smallerAvail (UniverseMinus _) (AvailRegs _) = False smallerAvail (AvailRegs s) (AvailRegs s') = sizeUniqSet s < sizeUniqSet s' smallerAvail (UniverseMinus s) (UniverseMinus s') = sizeUniqSet s > sizeUniqSet s' -extendAvail :: AvailRegs -> LocalReg -> AvailRegs -extendAvail (UniverseMinus s) r = UniverseMinus (deleteFromRegSet s r) -extendAvail (AvailRegs s) r = AvailRegs (extendRegSet s r) +--extendAvail :: AvailRegs -> LocalReg -> AvailRegs +--extendAvail (UniverseMinus s) r = UniverseMinus (deleteFromRegSet s r) +--extendAvail (AvailRegs s) r = AvailRegs (extendRegSet s r) deleteFromAvail :: AvailRegs -> LocalReg -> AvailRegs deleteFromAvail (UniverseMinus s) r = UniverseMinus (extendRegSet s r) @@ -237,105 +228,83 @@ elemAvail :: AvailRegs -> LocalReg -> Bool elemAvail (UniverseMinus s) r = not $ elemRegSet r s elemAvail (AvailRegs s) r = elemRegSet r s -cmmAvailableReloads :: LGraph M Last -> BlockEnv AvailRegs -cmmAvailableReloads g = env - where env = runDFA availRegsLattice $ - do run_f_anal transfer (fact_bot availRegsLattice) g - allFacts - transfer :: FAnalysis M Last AvailRegs - transfer = FComp "available-reloads analysis" first middle last exit - exit _ = LastOutFacts [] - first avail _ = avail - middle = flip middleAvail - last = lastAvail +type CmmAvail = BlockEnv AvailRegs +type AvailFix = FuelMonad (ForwardFixedPoint Middle Last AvailRegs ()) +cmmAvailableReloads :: LGraph Middle Last -> FuelMonad CmmAvail +cmmAvailableReloads g = liftM zdfFpFacts $ (res :: AvailFix) + where res = zdfSolveFromL emptyBlockEnv "available reloads" availRegsLattice + avail_reloads_transfer empty g + empty = fact_bot availRegsLattice + +avail_reloads_transfer :: ForwardTransfers Middle Last AvailRegs +avail_reloads_transfer = ForwardTransfers first middle last id + where first avail _ = avail + middle = flip middleAvail + last = lastAvail -- | The transfer equations use the traditional 'gen' and 'kill' -- notations, which should be familiar from the dragon book. -agen, akill :: UserOfLocalRegs a => a -> AvailRegs -> AvailRegs -agen a live = foldRegsUsed extendAvail live a +--agen, +akill :: UserOfLocalRegs a => a -> AvailRegs -> AvailRegs +--agen a live = foldRegsUsed extendAvail live a akill a live = foldRegsUsed deleteFromAvail live a -middleAvail :: M -> AvailRegs -> AvailRegs -middleAvail (Spill _) = id -middleAvail (Reload regs) = agen regs -middleAvail (NotSpillOrReload m) = middle m - where middle (MidComment {}) = id - middle (MidAssign lhs _expr) = akill lhs - middle (MidStore {}) = id - middle (MidUnsafeCall _tgt ress _args) = akill ress - middle (CopyIn _ formals _) = akill formals - middle (CopyOut {}) = id +-- Note: you can't sink the reload past a use. +middleAvail :: Middle -> AvailRegs -> AvailRegs +middleAvail m = middle m + where middle m live = middle' m $ foldRegsUsed deleteFromAvail live m + middle' (MidComment {}) live = live + middle' (MidAssign lhs _expr) live = akill lhs live + middle' (MidStore {}) live = live + middle' (MidForeignCall _ _tgt ress _args) _ = AvailRegs emptyRegSet lastAvail :: AvailRegs -> Last -> LastOutFacts AvailRegs -lastAvail _ (LastCall _ (Just k)) = LastOutFacts [(k, AvailRegs emptyRegSet)] +lastAvail _ (LastCall _ (Just k) _ _) = LastOutFacts [(k, AvailRegs emptyRegSet)] lastAvail avail l = LastOutFacts $ map (\id -> (id, avail)) $ succs l -insertLateReloads :: LGraph M Last -> DFTx (LGraph M Last) -insertLateReloads g = mapM_blocks insertM g - where env = cmmAvailableReloads g - avail id = lookupBlockEnv env id `orElse` AvailRegs emptyRegSet - insertM b = functionalDFTx "late reloads" (insert b) - insert (Block id tail) fuel = propagate (ZFirst id) (avail id) tail fuel - propagate h avail (ZTail m t) fuel = - let (h', fuel') = maybe_add_reload h avail m fuel in - propagate (ZHead h' m) (middleAvail m avail) t fuel' - propagate h avail (ZLast l) fuel = - let (h', fuel') = maybe_add_reload h avail l fuel in - (zipht h' (ZLast l), fuel') - maybe_add_reload h avail node fuel = - let used = foldRegsUsed - (\u r -> if elemAvail avail r then extendRegSet u r else u) - emptyRegSet node - in if fuel == 0 || isEmptyUniqSet used then (h, fuel) - else (ZHead h (Reload used), fuel-1) - - -removeDeadAssignmentsAndReloads :: BPass M Last DualLive -removeDeadAssignmentsAndReloads = a_ft_b dualLiveness remove_deads - where remove_deads = BComp "dead-assignment & -reload elim" exit last middle first - exit = Nothing - last = \_ _ -> Nothing - middle = middleRemoveDeads - first _ _ = Nothing +type LateReloadFix = FuelMonad (ForwardFixedPoint Middle Last AvailRegs CmmGraph) -middleRemoveDeads :: DualLive -> M -> Maybe (Graph M Last) -middleRemoveDeads _ (Spill _) = Nothing -middleRemoveDeads live (Reload s) = - if sizeUniqSet worth_reloading < sizeUniqSet s then - Just $ if isEmptyUniqSet worth_reloading then emptyGraph - else graphOfMiddles [Reload worth_reloading] - else - Nothing - where worth_reloading = intersectUniqSets s (in_regs live) -middleRemoveDeads live (NotSpillOrReload m) = middle m +insertLateReloads :: (LGraph Middle Last) -> FuelMonad (LGraph Middle Last) +insertLateReloads g = liftM zdfFpContents $ (res :: LateReloadFix) + where res = zdfFRewriteFromL RewriteShallow emptyBlockEnv "insert late reloads" + availRegsLattice avail_reloads_transfer rewrites bot g + bot = fact_bot availRegsLattice + rewrites = ForwardRewrites first middle last exit + first _ _ = Nothing + middle :: AvailRegs -> Middle -> Maybe (AGraph Middle Last) + last :: AvailRegs -> Last -> Maybe (AGraph Middle Last) + middle avail m = maybe_reload_before avail m (ZTail m (ZLast LastExit)) + last avail l = maybe_reload_before avail l (ZLast (LastOther l)) + exit _ = Nothing + maybe_reload_before avail node tail = + let used = filterRegsUsed (elemAvail avail) node + in if isEmptyUniqSet used then Nothing + else Just $ mkZTail $ reloadTail used tail + +removeDeadAssignmentsAndReloads :: BlockSet -> (LGraph Middle Last) -> FuelMonad (LGraph Middle Last) +removeDeadAssignmentsAndReloads procPoints g@(LGraph entry _ _) = + liftM zdfFpContents $ (res :: LiveReloadFix (LGraph Middle Last)) + where res = zdfBRewriteFromL RewriteDeep emptyBlockEnv "dead-assignment & -reload elim" + dualLiveLattice (dualLiveTransfers entry procPoints) + rewrites (fact_bot dualLiveLattice) g + rewrites = BackwardRewrites first middle last exit + exit = Nothing + last = \_ _ -> Nothing + middle = middleRemoveDeads + first _ _ = Nothing + +middleRemoveDeads :: DualLive -> Middle -> Maybe (AGraph Middle Last) +middleRemoveDeads live m = middle m where middle (MidAssign (CmmLocal reg') _) - | not (reg' `elemRegSet` in_regs live) = Just emptyGraph + | not (reg' `elemRegSet` in_regs live) = Just emptyAGraph middle _ = Nothing --------------------- --- register usage - -instance UserOfLocalRegs m => UserOfLocalRegs (ExtendWithSpills m) where - foldRegsUsed f z (Spill regs) = foldRegsUsed f z regs - foldRegsUsed _f z (Reload _) = z - foldRegsUsed f z (NotSpillOrReload m) = foldRegsUsed f z m - ---------------------- -- prettyprinting -instance Outputable m => Outputable (ExtendWithSpills m) where - ppr (Spill regs) = ppr_regs "Spill" regs - ppr (Reload regs) = ppr_regs "Reload" regs - ppr (NotSpillOrReload m) = ppr m - -instance Outputable (LGraph M Last) where - ppr = pprLgraph - -instance DebugNodes M Last - ppr_regs :: String -> RegSet -> SDoc ppr_regs s regs = text s <+> commafy (map ppr $ uniqSetToList regs) where commafy xs = hsep $ punctuate comma xs