X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fcmm%2FCmmSpillReload.hs;h=fb6931e006556549fd707af13ba6f773cea87358;hp=63e005851e629244335d3e72372f09922345e0d3;hb=d436c70d43fb905c63220040168295e473f4b90a;hpb=569348e87434f2a8d9e18dccac8b4a563b4eb363 diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index 63e0058..fb6931e 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -1,47 +1,46 @@ 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 + , insertLateReloads + , removeDeadAssignmentsAndReloads ) where + +import BlockId import CmmExpr import CmmTx import CmmLiveZ import DFMonad -import FastString -import Maybe import MkZipCfg -import Outputable hiding (empty) -import qualified Outputable as PP -import Panic +import OptimizationFuel import PprCmm() -import UniqSet import ZipCfg import ZipCfgCmmRep import ZipDataflow +import Monad +import Outputable hiding (empty) +import qualified Outputable as PP +import Panic +import UniqSet + +import Maybe +import Prelude hiding (zip) + -- The point of this module is to insert spills and reloads to -- 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 @@ -60,14 +59,14 @@ 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 dualLiveLattice = - DataflowLattice "variables live in registers and on stack" empty add False + DataflowLattice "variables live in registers and on stack" empty add True where empty = DualLive emptyRegSet emptyRegSet -- | compute in the Tx monad to track whether anything has changed add new old = do stack <- add1 (on_stack new) (on_stack old) @@ -75,120 +74,108 @@ 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) +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 -dualLiveness :: BAnalysis M Last DualLive -dualLiveness = BComp "dual liveness" exit last middle first - where exit = empty - last = lastDualLiveness - middle = middleDualLiveness - first live _id = live +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 - -- ^ 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 m@(Spill regs) = - -- live-in on-stack requirements are satisfied; - -- live-out in-regs obligations are created - my_trace "before" (f4sep [ppr m, text "liveness is", ppr live']) $ - live' - where live' = DualLive { on_stack = on_stack live `minusRegSet` regs - , in_regs = in_regs live `plusRegSet` regs } - -middleDualLiveness live m@(Reload regs) = - -- live-in in-regs requirements are satisfied; - -- live-out on-stack obligations are created - my_trace "before" (f4sep [ppr m, text "liveness is", ppr live']) $ - live' - where live' = DualLive { on_stack = on_stack live `plusRegSet` regs - , in_regs = in_regs live `minusRegSet` regs } - -middleDualLiveness live (NotSpillOrReload m) = changeRegs (middleLiveness m) live - -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 - -- only 'formals' can be in regs 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 $ +dualLiveTransfers :: BlockId -> BlockSet -> BackwardTransfers Middle Last DualLive +dualLiveTransfers entry procPoints = BackwardTransfers first middle last + where last = lastDualLiveness + middle = middleDualLiveness + first id live = 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 :: Middle -> DualLive -> DualLive +middleDualLiveness m live = + 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 :: Last -> (BlockId -> DualLive) -> DualLive +lastDualLiveness l env = last l + where last (LastBranch id) = env id + last l@(LastCall _ Nothing _ _ _) = changeRegs (gen l . kill l) empty + last l@(LastCall _ (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 _ t f) = + changeRegs (gen l . kill l) $ dualUnion (env t) (env f) + last l@(LastSwitch _ 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 id live = + if id /= entry && elemBlockSet id procPoints then + case map reload (uniqSetToList (in_regs live)) of + [] -> Nothing + is -> Just (mkMiddles is) + else Nothing + +middleInsertSpillsAndReloads :: Middle -> DualLive -> Maybe (AGraph Middle Last) +middleInsertSpillsAndReloads m live = 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 - -show_regs :: String -> RegSet -> Middle -show_regs s regs = MidComment $ mkFastString $ showSDoc $ ppr_regs s regs +-- Generating spill and reload code +regSlot :: LocalReg -> CmmExpr +regSlot r = CmmStackSlot (RegSlot r) (widthInBytes $ typeWidth $ localRegType r) +spill, reload :: LocalReg -> Middle +spill r = MidStore (regSlot r) (CmmReg $ CmmLocal r) +reload r = MidAssign (CmmLocal r) (CmmLoad (regSlot r) $ localRegType r) ---------------------------------------------------------------- --- sinking reloads @@ -204,7 +191,7 @@ 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 where empty = UniverseMinus emptyRegSet -- | compute in the Tx monad to track whether anything has changed add new old = @@ -228,59 +215,81 @@ 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) -deleteFromAvail (AvailRegs s) r = AvailRegs (deleteFromRegSet s r) - -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 - - --- | 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 -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 (MidNop) = id - 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 - -lastAvail :: AvailRegs -> Last -> LastOutFacts AvailRegs -lastAvail _ (LastCall _ (Just k)) = LastOutFacts [(k, AvailRegs emptyRegSet)] -lastAvail avail l = LastOutFacts $ map (\id -> (id, avail)) $ succs l +delFromAvail :: AvailRegs -> LocalReg -> AvailRegs +delFromAvail (UniverseMinus s) r = UniverseMinus (extendRegSet s r) +delFromAvail (AvailRegs s) r = AvailRegs (deleteFromRegSet s r) + +elemAvail :: AvailRegs -> LocalReg -> Bool +elemAvail (UniverseMinus s) r = not $ elemRegSet r s +elemAvail (AvailRegs s) r = elemRegSet r s + +type AvailFix = FuelMonad (ForwardFixedPoint Middle Last AvailRegs ()) + +cmmAvailableReloads :: LGraph Middle Last -> FuelMonad (BlockEnv AvailRegs) +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 (flip const) middleAvail lastAvail id + +middleAvail :: Middle -> AvailRegs -> AvailRegs +middleAvail (MidAssign (CmmLocal r) (CmmLoad l _)) avail + | l `isStackSlotOf` r = extendAvail avail r +middleAvail (MidAssign lhs _) avail = foldRegsDefd delFromAvail avail lhs +middleAvail (MidStore l (CmmReg (CmmLocal r))) avail + | l `isStackSlotOf` r = avail +middleAvail (MidStore (CmmStackSlot (RegSlot r) _) _) avail = delFromAvail avail r +middleAvail (MidStore {}) avail = avail +middleAvail (MidForeignCall {}) _ = AvailRegs emptyRegSet +middleAvail (MidComment {}) avail = avail + +lastAvail :: Last -> AvailRegs -> LastOutFacts AvailRegs +lastAvail (LastCall _ (Just k) _ _ _) _ = LastOutFacts [(k, AvailRegs emptyRegSet)] +lastAvail l avail = LastOutFacts $ map (\id -> (id, avail)) $ succs l + +type LateReloadFix = FuelMonad (ForwardFixedPoint Middle Last AvailRegs CmmGraph) + +availRewrites :: ForwardRewrites Middle Last AvailRegs +availRewrites = ForwardRewrites first middle last exit + where first _ _ = Nothing + middle m avail = maybe_reload_before avail m (mkMiddle m) + last l avail = maybe_reload_before avail l (mkLast l) + exit _ = Nothing + maybe_reload_before avail node tail = + let used = filterRegsUsed (elemAvail avail) node + in if isEmptyUniqSet used then Nothing + else Just $ reloadTail used tail + reloadTail regset t = foldl rel t $ uniqSetToList regset + where rel t r = mkMiddle (reload r) <*> t + + +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 availRewrites bot g + bot = fact_bot availRegsLattice + +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 nothing middleRemoveDeads nothing Nothing + nothing _ _ = Nothing + +middleRemoveDeads :: Middle -> DualLive -> Maybe (AGraph Middle Last) +middleRemoveDeads (MidAssign (CmmLocal reg') _) live + | not (reg' `elemRegSet` in_regs live) = Just emptyAGraph +middleRemoveDeads _ _ = Nothing + --------------------- -- 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 @@ -296,8 +305,10 @@ instance Outputable DualLive where else (ppr_regs "live on stack =" stack)] instance Outputable AvailRegs where - ppr (UniverseMinus s) = ppr_regs "available = all but" s - ppr (AvailRegs s) = ppr_regs "available = " s + ppr (UniverseMinus s) = if isEmptyUniqSet s then text "" + else ppr_regs "available = all but" s + ppr (AvailRegs s) = if isEmptyUniqSet s then text "" + else ppr_regs "available = " s my_trace :: String -> SDoc -> a -> a my_trace = if False then pprTrace else \_ _ a -> a