X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmSpillReload.hs;h=a8839a87985de736923e2c0f4c679faea9e08d17;hb=7fc01c4671980ea3c66d549c0ece4d82fd3f5ade;hp=2b54b9ac36d78ee7cfbc3abb24158386c4293c41;hpb=25628e2771424cae1b3366322e8ce6f8a85440f9;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index 2b54b9a..a8839a8 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -1,63 +1,58 @@ +#if __GLASGOW_HASKELL__ >= 611 +{-# OPTIONS_GHC -XNoMonoLocalBinds #-} +#endif +-- Norman likes local bindings +-- If this module lives on I'd like to get rid of this flag in due course module CmmSpillReload - ( ExtendWithSpills(..) - , DualLive(..) + ( DualLive(..) , dualLiveLattice, dualLiveTransfers, dualLiveness --, insertSpillsAndReloads --- XXX todo check live-in at entry against formals , dualLivenessWithInsertion - , elimSpillAndReload , availRegsLattice , cmmAvailableReloads , insertLateReloads - , insertLateReloads' , removeDeadAssignmentsAndReloads ) where +import BlockId import CmmExpr import CmmTx import CmmLiveZ import DFMonad import MkZipCfg -import OptimizationFuel import PprCmm() -import StackSlot import ZipCfg import ZipCfgCmmRep import ZipDataflow -import Maybes -import Monad +import Control.Monad import Outputable hiding (empty) import qualified Outputable as PP -import Panic import UniqSet -import Maybe +import Data.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 --- 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 --- after a call is available on the stack. Spills are pushed back to --- their reaching definitions, but reloads are dropped wherever needed --- and will have to be sunk by a later forward transformation. +{- Note [Overview of spill/reload] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +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 be followed by a +forward transformation to sink reloads as deeply as possible, so as +to reduce register pressure. + +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 +after a call is available on the stack. Spills are pushed back to +their reaching definitions, but reloads are dropped wherever needed +and will have to be sunk by a later forward transformation. +-} data DualLive = DualLive { on_stack :: RegSet, in_regs :: RegSet } @@ -70,14 +65,14 @@ 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 True + DataflowLattice "variables live in registers and on stack" empty add False 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) @@ -85,139 +80,108 @@ dualLiveLattice = return $ DualLive stack regs add1 = fact_add_to liveLattice -type LiveReloadFix a = FuelMonad (BackwardFixedPoint M Last DualLive a) +type LiveReloadFix a = FuelMonad (BackwardFixedPoint Middle Last DualLive a) -dualLivenessWithInsertion :: BlockSet -> (Graph M Last) -> FuelMonad (Graph M Last) -dualLivenessWithInsertion procPoints g = - liftM zdfFpContents $ (res :: LiveReloadFix (Graph M Last)) - where res = zdfRewriteFrom RewriteDeep emptyBlockEnv "dual liveness with insertion" - dualLiveLattice (dualLiveTransfers procPoints) - (insertSpillAndReloadRewrites procPoints) empty g +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 --- = a_ft_b_unlimited dualLiveness insertSpillsAndReloads -dualLiveness :: BlockSet -> Graph M Last -> FuelMonad (BlockEnv DualLive) -dualLiveness procPoints g = liftM zdfFpFacts $ (res :: LiveReloadFix ()) - where res = zdfSolveFrom emptyBlockEnv "dual liveness" dualLiveLattice - (dualLiveTransfers procPoints) empty g +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 -dualLiveTransfers :: BlockSet -> BackwardTransfers M Last DualLive -dualLiveTransfers procPoints = BackwardTransfers first middle last +dualLiveTransfers :: BlockId -> BlockSet -> BackwardTransfers Middle Last DualLive +dualLiveTransfers entry procPoints = BackwardTransfers first middle last where last = lastDualLiveness middle = middleDualLiveness - first live _id = - if elemBlockSet _id procPoints then -- live at procPoint => spill + 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 :: 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 } - -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 - let live = env k in - if isEmptyUniqSet (in_regs live) then - DualLive (on_stack live) (gen tgt emptyRegSet) - else - pprTrace "Offending party:" (ppr k <+> ppr live) $ - 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 $ +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 - -insertSpillAndReloadRewrites :: BlockSet -> BackwardRewrites M Last DualLive Graph -insertSpillAndReloadRewrites procPoints = BackwardRewrites first middle last exit +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 elemBlockSet id procPoints && not (isEmptyUniqSet reloads) then - Just $ graphOfMiddles $ [Reload reloads] + 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 - where reloads = in_regs live - -middleInsertSpillsAndReloads :: DualLive -> M -> Maybe (Graph M Last) -middleInsertSpillsAndReloads _ (Spill _) = Nothing -middleInsertSpillsAndReloads _ (Reload _) = Nothing -middleInsertSpillsAndReloads live m@(NotSpillOrReload nsr) = middle nsr - where middle (MidAssign (CmmLocal reg) _) = +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 $ graphOfMiddles [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 = filterRegsUsed is_stack_var formals - -- a formal that is expected on the stack; must spill - in if isEmptyUniqSet regs' && isEmptyUniqSet needs_spilling then - Nothing - else - let code = if isEmptyUniqSet regs' then [] - else Reload regs' : [] - code' = if isEmptyUniqSet needs_spilling then code - else Spill needs_spilling : code - 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 (m : code') + 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-- - -elimSpillAndReload :: StackSlotMap -> LGraph M l -> FuelMonad (StackSlotMap, LGraph Middle l) -elimSpillAndReload slots g = fold_blocks block (return (slots, [])) g >>= toGraph - where toGraph (slots, l) = return (slots, of_block_list (lg_entry g) l) - block (Block id t) z = - do (slots, blocks) <- z - (slots, t) <- tail t slots - return (slots, Block id t : blocks) - tail (ZLast l) slots = return (slots, ZLast l) - tail (ZTail m t) slots = - do (slots, t) <- tail t slots - middle m t slots - middle (Spill regs) t slots = foldUniqSet spill (return (slots, t)) regs - middle (Reload regs) t slots = foldUniqSet reload (return (slots, t)) regs - middle (NotSpillOrReload m) t slots = return (slots, ZTail m t) - move f r z = do let reg = CmmLocal r - (slots, t) <- z - (slots, slot) <- getSlot slots reg - return (slots, ZTail (f (CmmStack slot) reg) t) - spill = move (\ slot reg -> MidAssign slot (CmmReg reg)) - reload = move (\ slot reg -> MidAssign reg (CmmReg slot)) +-- 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 @@ -234,7 +198,6 @@ data AvailRegs = UniverseMinus RegSet availRegsLattice :: DataflowLattice AvailRegs 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 = @@ -258,138 +221,81 @@ 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) +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 CmmAvail = BlockEnv AvailRegs -type AvailFix = FuelMonad (ForwardFixedPoint M Last AvailRegs ()) +type AvailFix = FuelMonad (ForwardFixedPoint Middle Last AvailRegs ()) -cmmAvailableReloads :: Graph M Last -> FuelMonad CmmAvail +cmmAvailableReloads :: LGraph Middle Last -> FuelMonad (BlockEnv AvailRegs) cmmAvailableReloads g = liftM zdfFpFacts $ (res :: AvailFix) - where res = zdfSolveFrom emptyBlockEnv "available reloads" availRegsLattice - avail_reloads_transfer empty g - empty = (fact_bot availRegsLattice) - -avail_reloads_transfer :: ForwardTransfers M 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 -akill a live = foldRegsUsed deleteFromAvail live a - --- Note: you can't sink the reload past a use. -middleAvail :: M -> AvailRegs -> AvailRegs -middleAvail (Spill _) = id -middleAvail (Reload regs) = agen regs -middleAvail (NotSpillOrReload m) = middle m - where middle m live = middle' m $ foldRegsUsed deleteFromAvail live m - middle' (MidComment {}) = id - middle' (MidAssign lhs _expr) = akill lhs - middle' (MidStore {}) = id - middle' (MidUnsafeCall _tgt ress _args) = akill ress - middle' (MidAddToContext {}) = id - 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 - -insertLateReloads :: Graph M Last -> FuelMonad (Graph M Last) -insertLateReloads g = - do env <- cmmAvailableReloads g - g <- lGraphOfGraph g - liftM graphOfLGraph $ mapM_blocks (insertM env) g - where insertM env b = fuelConsumingPass "late reloads" (insert b) - where avail id = lookupBlockEnv env id `orElse` AvailRegs emptyRegSet - 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 = filterRegsUsed (elemAvail avail) node - in if not (canRewriteWithFuel fuel) || isEmptyUniqSet used - then (h,fuel) - else (ZHead h (Reload used), oneLessFuel fuel) - -type LateReloadFix = FuelMonad (ForwardFixedPoint M Last AvailRegs (Graph M Last)) - -insertLateReloads' :: (Graph M Last) -> FuelMonad (Graph M Last) -insertLateReloads' g = liftM zdfFpContents $ (res :: LateReloadFix) - where res = zdfRewriteFrom RewriteShallow emptyBlockEnv "insert late reloads" - availRegsLattice avail_reloads_transfer rewrites bot g + 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 - rewrites = ForwardRewrites first middle last exit - first _ _ = Nothing - middle :: AvailRegs -> M -> Maybe (Graph M Last) - last :: AvailRegs -> Last -> Maybe (Graph M 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 $ graphOfZTail $ ZTail (Reload used) tail -removeDeadAssignmentsAndReloads :: BlockSet -> (Graph M Last) -> FuelMonad (Graph M Last) -removeDeadAssignmentsAndReloads procPoints g = - liftM zdfFpContents $ (res :: LiveReloadFix (Graph M Last)) - where res = zdfRewriteFrom RewriteDeep emptyBlockEnv "dead-assignment & -reload elim" - dualLiveLattice (dualLiveTransfers procPoints) +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 -> 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 - where middle (MidAssign (CmmLocal reg') _) - | not (reg' `elemRegSet` in_regs live) = Just emptyGraph - middle _ = Nothing - - + rewrites = BackwardRewrites nothing middleRemoveDeads nothing Nothing + nothing _ _ = Nothing ---------------------- --- register usage +middleRemoveDeads :: Middle -> DualLive -> Maybe (AGraph Middle Last) +middleRemoveDeads (MidAssign (CmmLocal reg') _) live + | not (reg' `elemRegSet` in_regs live) = Just emptyAGraph +middleRemoveDeads _ _ = Nothing + -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 m => DebugNodes (ExtendWithSpills 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