X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fcmm%2FCmmSpillReload.hs;h=707a571b3fcbf7901dd3745011d49134038dc290;hb=a1515d75e38a32d69636c98bb590f6195e2ab3d1;hp=3142e8e62d5816587b5b40138053fca601ef40e8;hpb=fd8d04119e849f9c713d3e697228846d93c5ca69;p=ghc-hetmet.git diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index 3142e8e..707a571 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -1,4 +1,3 @@ -{-# OPTIONS -Wall -fno-warn-name-shadowing #-} module CmmSpillReload ( ExtendWithSpills(..) @@ -7,23 +6,35 @@ module CmmSpillReload , insertSpillsAndReloads --- XXX todo check live-in at entry against formals , dualLivenessWithInsertion , spillAndReloadComments + + , availRegsLattice + , cmmAvailableReloads + , insertLateReloads + , insertLateReloads' + , removeDeadAssignmentsAndReloads ) where + import CmmExpr -import CmmTx() +import CmmTx import CmmLiveZ import DFMonad -import FastString -import Maybe import MkZipCfg +import PprCmm() +import ZipCfg +import ZipCfgCmmRep +import ZipDataflow0 + +import FastString +import Maybes import Outputable hiding (empty) import qualified Outputable as PP import Panic -import PprCmm() import UniqSet -import ZipCfg -import ZipCfgCmm -import ZipDataflow +import UniqSupply + +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 @@ -76,7 +87,6 @@ dualLiveLattice = dualLivenessWithInsertion :: BPass M Last DualLive dualLivenessWithInsertion = a_ft_b_unlimited dualLiveness insertSpillsAndReloads - dualLiveness :: BAnalysis M Last DualLive dualLiveness = BComp "dual liveness" exit last middle first where exit = empty @@ -91,36 +101,31 @@ dualLiveness = BComp "dual liveness" exit last middle first -- this pass again middleDualLiveness :: DualLive -> M -> DualLive -middleDualLiveness live m@(Spill regs) = +middleDualLiveness live (Spill regs) = live' -- 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 } + , in_regs = in_regs live `plusRegSet` regs } -middleDualLiveness live m@(Reload regs) = +middleDualLiveness live (Reload regs) = live' -- 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 } + 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 ress) = changeRegs (gen ress) empty - last (LastJump e args) = changeRegs (gen e . gen args) empty - last (LastBranch id args) = changeRegs (gen args) $ env id - last (LastCall tgt args Nothing) = changeRegs (gen tgt. gen args) empty - last (LastCall tgt args (Just k)) = + 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 $ gen args emptyRegSet) + 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) @@ -147,35 +152,33 @@ insertSpillsAndReloads = BComp "CPS spiller" exit last middle first 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', +middleInsertSpillsAndReloads live m@(NotSpillOrReload nsr) = middle nsr + 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']] + 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 = -- 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 + 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 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 + 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 middles + Just $ graphOfMiddles (m : code') middle _ = Nothing -- | For conversion back to vanilla C-- @@ -191,8 +194,6 @@ show_regs s regs = MidComment $ mkFastString $ showSDoc $ ppr_regs s regs ---------------------------------------------------------------- --- sinking reloads -{- - -- The idea is to compute at each point the set of registers such that -- on every path to the point, the register is defined by a Reload -- instruction. Then, if a use appears at such a point, we can safely @@ -202,22 +203,154 @@ show_regs s regs = MidComment $ mkFastString $ showSDoc $ ppr_regs s regs data AvailRegs = UniverseMinus RegSet | AvailRegs RegSet + availRegsLattice :: DataflowLattice AvailRegs -availRegsLattice = - DataflowLattice "register gotten from reloads" empty add False - where empty = DualLive emptyRegSet emptyRegSet +availRegsLattice = DataflowLattice "register gotten from reloads" empty add True + where empty = UniverseMinus emptyRegSet -- | compute in the Tx monad to track whether anything has changed - add new old = do stack <- add1 (on_stack new) (on_stack old) - regs <- add1 (in_regs new) (in_regs old) - return $ DualLive stack regs - add1 = fact_add_to liveLattice - - + add new old = + let join = interAvail new old in + if join `smallerAvail` old then aTx join else noTx join + + +interAvail :: AvailRegs -> AvailRegs -> AvailRegs +interAvail (UniverseMinus s) (UniverseMinus s') = UniverseMinus (s `plusRegSet` s') +interAvail (AvailRegs s) (AvailRegs s') = AvailRegs (s `timesRegSet` s') +interAvail (AvailRegs s) (UniverseMinus s') = AvailRegs (s `minusRegSet` s') +interAvail (UniverseMinus s) (AvailRegs s') = AvailRegs (s' `minusRegSet` s ) + +smallerAvail :: AvailRegs -> AvailRegs -> Bool +smallerAvail (AvailRegs _) (UniverseMinus _) = True +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) + +deleteFromAvail :: AvailRegs -> LocalReg -> AvailRegs +deleteFromAvail (UniverseMinus s) r = UniverseMinus (extendRegSet s r) +deleteFromAvail (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 + +cmmAvailableReloads :: LGraph M Last -> BlockEnv AvailRegs +cmmAvailableReloads g = env + where env = runDFA availRegsLattice $ + do run_f_anal avail_reloads_transfer (fact_bot availRegsLattice) g + allFacts + +avail_reloads_transfer :: FAnalysis M Last AvailRegs +avail_reloads_transfer = FComp "available-reloads analysis" first middle last exit + where exit avail = avail + 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 (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 :: LGraph M Last -> FuelMonad (LGraph M Last) +insertLateReloads g = mapM_blocks insertM g + where env = cmmAvailableReloads g + avail id = lookupBlockEnv env id `orElse` AvailRegs emptyRegSet + insertM b = fuelConsumingPass "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 = filterRegsUsed (elemAvail avail) node + in if not (canRewriteWithFuel fuel) || isEmptyUniqSet used then (h,fuel) + else (ZHead h (Reload used), oneLessFuel fuel) + +insertLateReloads' :: UniqSupply -> (Graph M Last) -> FuelMonad (Graph M Last) +insertLateReloads' us g = + runDFM us availRegsLattice $ + f_shallow_rewrite avail_reloads_transfer insert bot g + where bot = fact_bot availRegsLattice + insert = null_f_ft { fc_middle_out = middle, fc_last_outs = last } + 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)) + 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 + +_lateReloadsWithoutFuel :: LGraph M Last -> LGraph M Last +_lateReloadsWithoutFuel g = map_blocks insert g + where env = cmmAvailableReloads g + avail id = lookupBlockEnv env id `orElse` AvailRegs emptyRegSet + insert (Block id tail) = propagate (ZFirst id) (avail id) tail + propagate h avail (ZTail m t) = + propagate (ZHead (maybe_add_reload h avail m) m) (middleAvail m avail) t + propagate h avail (ZLast l) = + zipht (maybe_add_reload h avail l) (ZLast l) + maybe_add_reload h avail node = + let used = filterRegsUsed (elemAvail avail) node + in if isEmptyUniqSet used then h + else ZHead h (Reload used) + + +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 +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 + --} +--------------------- +-- 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 @@ -227,10 +360,7 @@ instance Outputable m => Outputable (ExtendWithSpills m) where ppr (Reload regs) = ppr_regs "Reload" regs ppr (NotSpillOrReload m) = ppr m -instance Outputable (LGraph M Last) where - ppr = pprLgraph - -instance DebugNodes M Last +instance Outputable m => DebugNodes (ExtendWithSpills m) Last ppr_regs :: String -> RegSet -> SDoc ppr_regs s regs = text s <+> commafy (map ppr $ uniqSetToList regs) @@ -246,6 +376,12 @@ instance Outputable DualLive where if isEmptyUniqSet stack then PP.empty else (ppr_regs "live on stack =" stack)] +instance Outputable AvailRegs where + 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