From 6251f729b80fa3ece8447a979e9002a2541e9cef Mon Sep 17 00:00:00 2001 From: "Edward Z. Yang" Date: Fri, 15 Apr 2011 10:32:33 +0100 Subject: [PATCH] Revert "Generalized assignment rewriting pass." This reverts commit 2ec796239b782505cfb305af2789abcfa820baaf. --- compiler/cmm/CmmCPS.hs | 5 +- compiler/cmm/CmmSpillReload.hs | 496 ++++++++-------------------------------- 2 files changed, 103 insertions(+), 398 deletions(-) diff --git a/compiler/cmm/CmmCPS.hs b/compiler/cmm/CmmCPS.hs index 6e0cd33..b9f6db3 100644 --- a/compiler/cmm/CmmCPS.hs +++ b/compiler/cmm/CmmCPS.hs @@ -95,8 +95,9 @@ cpsTop hsc_env (CmmProc h@(TopInfo {stack_info=StackInfo {arg_space=entry_off}}) (dualLivenessWithInsertion procPoints) g -- Insert spills at defns; reloads at return points g <- - runOptimization $ rewriteAssignments g - dump Opt_D_dump_cmmz "Post rewrite assignments" g + -- pprTrace "pre insertLateReloads" (ppr g) $ + runOptimization $ insertLateReloads g -- Duplicate reloads just before uses + dump Opt_D_dump_cmmz "Post late reloads" g g <- -- pprTrace "post insertLateReloads" (ppr g) $ dual_rewrite runOptimization Opt_D_dump_cmmz "Dead Assignment Elimination" diff --git a/compiler/cmm/CmmSpillReload.hs b/compiler/cmm/CmmSpillReload.hs index d39bfa1..17364ad 100644 --- a/compiler/cmm/CmmSpillReload.hs +++ b/compiler/cmm/CmmSpillReload.hs @@ -1,8 +1,7 @@ -{-# LANGUAGE GADTs, NoMonoLocalBinds, FlexibleContexts, ViewPatterns #-} +{-# LANGUAGE GADTs,NoMonoLocalBinds #-} -- Norman likes local bindings -- If this module lives on I'd like to get rid of this flag in due course -{-# OPTIONS_GHC -fno-warn-warnings-deprecations #-} {-# OPTIONS_GHC -fno-warn-incomplete-patterns #-} #if __GLASGOW_HASKELL__ >= 701 -- GHC 7.0.1 improved incomplete pattern warnings with GADTs @@ -15,7 +14,9 @@ module CmmSpillReload --, insertSpillsAndReloads --- XXX todo check live-in at entry against formals , dualLivenessWithInsertion - , rewriteAssignments + , availRegsLattice + , cmmAvailableReloads + , insertLateReloads , removeDeadAssignmentsAndReloads ) where @@ -30,10 +31,8 @@ import Control.Monad import Outputable hiding (empty) import qualified Outputable as PP import UniqSet -import UniqFM -import Unique -import Compiler.Hoopl hiding (Unique) +import Compiler.Hoopl import Data.Maybe import Prelude hiding (succ, zip) @@ -173,6 +172,11 @@ insertSpillAndReloadRewrites graph procPoints = deepBwdRw3 first middle nothing text "after"{-, ppr m-}]) $ Just $ mkMiddles $ [m, spill reg] else Nothing + middle m@(CmmUnsafeForeignCall _ fs _) live = return $ + 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 _ _ = return Nothing nothing _ _ = return Nothing @@ -184,6 +188,91 @@ spill, reload :: LocalReg -> CmmNode O O spill r = CmmStore (regSlot r) (CmmReg $ CmmLocal r) reload r = CmmAssign (CmmLocal r) (CmmLoad (regSlot r) $ localRegType r) +---------------------------------------------------------------- +--- 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 +-- insert a Reload right before the use. Finally, we can eliminate +-- the early reloads along with other dead assignments. + +data AvailRegs = UniverseMinus RegSet + | AvailRegs RegSet + + +availRegsLattice :: DataflowLattice AvailRegs +availRegsLattice = DataflowLattice "register gotten from reloads" empty add + where empty = UniverseMinus emptyRegSet + -- | compute in the Tx monad to track whether anything has changed + add _ (OldFact old) (NewFact new) = + if join `smallerAvail` old then (SomeChange, join) else (NoChange, old) + where join = interAvail new old + + +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) + +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 + +cmmAvailableReloads :: CmmGraph -> FuelUniqSM (BlockEnv AvailRegs) +cmmAvailableReloads g = + liftM snd $ dataflowPassFwd g [(g_entry g, fact_bot availRegsLattice)] $ + analFwd availRegsLattice availReloadsTransfer + +availReloadsTransfer :: FwdTransfer CmmNode AvailRegs +availReloadsTransfer = mkFTransfer3 (flip const) middleAvail ((mkFactBase availRegsLattice .) . lastAvail) + +middleAvail :: CmmNode O O -> AvailRegs -> AvailRegs +middleAvail (CmmAssign (CmmLocal r) (CmmLoad l _)) avail + | l `isStackSlotOf` r = extendAvail avail r +middleAvail (CmmAssign lhs _) avail = foldRegsDefd delFromAvail avail lhs +middleAvail (CmmStore l (CmmReg (CmmLocal r))) avail + | l `isStackSlotOf` r = avail +middleAvail (CmmStore (CmmStackSlot (RegSlot r) _) _) avail = delFromAvail avail r +middleAvail (CmmStore {}) avail = avail +middleAvail (CmmUnsafeForeignCall {}) _ = AvailRegs emptyRegSet +middleAvail (CmmComment {}) avail = avail + +lastAvail :: CmmNode O C -> AvailRegs -> [(Label, AvailRegs)] +lastAvail (CmmCall _ (Just k) _ _ _) _ = [(k, AvailRegs emptyRegSet)] +lastAvail (CmmForeignCall {succ=k}) _ = [(k, AvailRegs emptyRegSet)] +lastAvail l avail = map (\id -> (id, avail)) $ successors l + +insertLateReloads :: CmmGraph -> FuelUniqSM CmmGraph +insertLateReloads g = + liftM fst $ dataflowPassFwd g [(g_entry g, fact_bot availRegsLattice)] $ + analRewFwd availRegsLattice availReloadsTransfer rewrites + where rewrites = mkFRewrite3 first middle last + first _ _ = return Nothing + middle m avail = return $ maybe_reload_before avail m (mkMiddle m) + last l avail = return $ maybe_reload_before avail l (mkLast l) + 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 + removeDeadAssignmentsAndReloads :: BlockSet -> CmmGraph -> FuelUniqSM CmmGraph removeDeadAssignmentsAndReloads procPoints g = liftM fst $ dataflowPassBwd g [] $ analRewBwd dualLiveLattice @@ -194,399 +283,10 @@ removeDeadAssignmentsAndReloads procPoints g = -- but GHC panics while compiling, see bug #4045. middle :: CmmNode O O -> Fact O DualLive -> CmmReplGraph O O middle (CmmAssign (CmmLocal reg') _) live | not (reg' `elemRegSet` in_regs live) = return $ Just emptyGraph - -- XXX maybe this should be somewhere else... - middle (CmmStore lhs (CmmLoad rhs _)) _ | lhs == rhs = return $ Just emptyGraph middle _ _ = return Nothing nothing _ _ = return Nothing ----------------------------------------------------------------- ---- Usage information - --- We decorate all register assignments with usage information, --- that is, the maximum number of times the register is referenced --- while it is live along all outgoing control paths. There are a few --- subtleties here: --- --- - If a register goes dead, and then becomes live again, the usages --- of the disjoint live range don't count towards the original range. --- --- a = 1; // used once --- b = a; --- a = 2; // used once --- c = a; --- --- - A register may be used multiple times, but these all reside in --- different control paths, such that any given execution only uses --- it once. In that case, the usage count may still be 1. --- --- a = 1; // used once --- if (b) { --- c = a + 3; --- } else { --- c = a + 1; --- } --- --- This policy corresponds to an inlining strategy that does not --- duplicate computation but may increase binary size. --- --- - If we naively implement a usage count, we have a counting to --- infinity problem across joins. Furthermore, knowing that --- something is used 2 or more times in one runtime execution isn't --- particularly useful for optimizations (inlining may be beneficial, --- but there's no way of knowing that without register pressure --- information.) --- --- while (...) { --- // first iteration, b used once --- // second iteration, b used twice --- // third iteration ... --- a = b; --- } --- // b used zero times --- --- There is an orthogonal question, which is that for every runtime --- execution, the register may be used only once, but if we inline it --- in every conditional path, the binary size might increase a lot. --- But tracking this information would be tricky, because it violates --- the finite lattice restriction Hoopl requires for termination; --- we'd thus need to supply an alternate proof, which is probably --- something we should defer until we actually have an optimization --- that would take advantage of this. (This might also interact --- strangely with liveness information.) --- --- a = ...; --- // a is used one time, but in X different paths --- case (b) of --- 1 -> ... a ... --- 2 -> ... a ... --- 3 -> ... a ... --- ... --- --- This analysis is very similar to liveness analysis; we just keep a --- little extra info. (Maybe we should move it to CmmLive, and subsume --- the old liveness analysis.) - -data RegUsage = SingleUse | ManyUse - deriving (Ord, Eq, Show) --- Absence in map = ZeroUse - -{- --- minBound is bottom, maxBound is top, least-upper-bound is max --- ToDo: Put this in Hoopl. Note that this isn't as useful as I --- originally hoped, because you usually want to leave out the bottom --- element when you have things like this put in maps. Maybe f is --- useful on its own as a combining function. -boundedOrdLattice :: (Bounded a, Ord a) => String -> DataflowLattice a -boundedOrdLattice n = DataflowLattice n minBound f - where f _ (OldFact x) (NewFact y) - | x >= y = (NoChange, x) - | otherwise = (SomeChange, y) --} - --- Custom node type we'll rewrite to. CmmAssign nodes to local --- registers are replaced with AssignLocal nodes. -data WithRegUsage n e x where - Plain :: n e x -> WithRegUsage n e x - AssignLocal :: LocalReg -> CmmExpr -> RegUsage -> WithRegUsage n O O - -instance UserOfLocalRegs (n e x) => UserOfLocalRegs (WithRegUsage n e x) where - foldRegsUsed f z (Plain n) = foldRegsUsed f z n - foldRegsUsed f z (AssignLocal _ e _) = foldRegsUsed f z e - -instance DefinerOfLocalRegs (n e x) => DefinerOfLocalRegs (WithRegUsage n e x) where - foldRegsDefd f z (Plain n) = foldRegsDefd f z n - foldRegsDefd f z (AssignLocal r _ _) = foldRegsDefd f z r - -instance NonLocal n => NonLocal (WithRegUsage n) where - entryLabel (Plain n) = entryLabel n - successors (Plain n) = successors n - -liftRegUsage :: Graph n e x -> Graph (WithRegUsage n) e x -liftRegUsage = mapGraph Plain - -eraseRegUsage :: Graph (WithRegUsage CmmNode) e x -> Graph CmmNode e x -eraseRegUsage = mapGraph f - where f :: WithRegUsage CmmNode e x -> CmmNode e x - f (AssignLocal l e _) = CmmAssign (CmmLocal l) e - f (Plain n) = n - -type UsageMap = UniqFM RegUsage - -usageLattice :: DataflowLattice UsageMap -usageLattice = DataflowLattice "usage counts for registers" emptyUFM (joinUFM f) - where f _ (OldFact x) (NewFact y) - | x >= y = (NoChange, x) - | otherwise = (SomeChange, y) - --- We reuse the names 'gen' and 'kill', although we're doing something --- slightly different from the Dragon Book -usageTransfer :: BwdTransfer (WithRegUsage CmmNode) UsageMap -usageTransfer = mkBTransfer3 first middle last - where first _ f = f - middle :: WithRegUsage CmmNode O O -> UsageMap -> UsageMap - middle n f = gen_kill n f - last :: WithRegUsage CmmNode O C -> FactBase UsageMap -> UsageMap - -- Checking for CmmCall/CmmForeignCall is unnecessary, because - -- spills/reloads have already occurred by the time we do this - -- analysis. - -- XXX Deprecated warning is puzzling: what label are we - -- supposed to use? - -- ToDo: With a bit more cleverness here, we can avoid - -- disappointment and heartbreak associated with the inability - -- to inline into CmmCall and CmmForeignCall by - -- over-estimating the usage to be ManyUse. - last n f = gen_kill n (joinOutFacts usageLattice n f) - gen_kill a = gen a . kill a - gen a f = foldRegsUsed increaseUsage f a - kill a f = foldRegsDefd delFromUFM f a - increaseUsage f r = addToUFM_C combine f r SingleUse - where combine _ _ = ManyUse - -usageRewrite :: BwdRewrite FuelUniqSM (WithRegUsage CmmNode) UsageMap -usageRewrite = mkBRewrite3 first middle last - where first _ _ = return Nothing - middle :: Monad m => WithRegUsage CmmNode O O -> UsageMap -> m (Maybe (Graph (WithRegUsage CmmNode) O O)) - middle (Plain (CmmAssign (CmmLocal l) e)) f - = return . Just - $ case lookupUFM f l of - Nothing -> emptyGraph - Just usage -> mkMiddle (AssignLocal l e usage) - middle _ _ = return Nothing - last _ _ = return Nothing - -type CmmGraphWithRegUsage = GenCmmGraph (WithRegUsage CmmNode) -annotateUsage :: CmmGraph -> FuelUniqSM (CmmGraphWithRegUsage) -annotateUsage vanilla_g = - let g = modifyGraph liftRegUsage vanilla_g - in liftM fst $ dataflowPassBwd g [(g_entry g, fact_bot usageLattice)] $ - analRewBwd usageLattice usageTransfer usageRewrite - ----------------------------------------------------------------- ---- Assignment tracking - --- The idea is to maintain a map of local registers do expressions, --- such that the value of that register is the same as the value of that --- expression at any given time. We can then do several things, --- as described by Assignment. - --- Assignment describes the various optimizations that are valid --- at a given point in the program. -data Assignment = --- This assignment can always be inlined. It is cheap or single-use. - AlwaysInline CmmExpr --- This assignment should be sunk down to its first use. (This will --- increase code size if the register is used in multiple control flow --- paths, but won't increase execution time, and the reduction of --- register pressure is worth it.) - | AlwaysSink CmmExpr --- We cannot safely optimize occurrences of this local register. (This --- corresponds to top in the lattice structure.) - | NeverOptimize - --- Extract the expression that is being assigned to -xassign :: Assignment -> Maybe CmmExpr -xassign (AlwaysInline e) = Just e -xassign (AlwaysSink e) = Just e -xassign NeverOptimize = Nothing - --- Extracts the expression, but only if they're the same constructor -xassign2 :: (Assignment, Assignment) -> Maybe (CmmExpr, CmmExpr) -xassign2 (AlwaysInline e, AlwaysInline e') = Just (e, e') -xassign2 (AlwaysSink e, AlwaysSink e') = Just (e, e') -xassign2 _ = Nothing - --- Note: We'd like to make decisions about "not optimizing" as soon as --- possible, because this will make running the transfer function more --- efficient. -type AssignmentMap = UniqFM Assignment - -assignmentLattice :: DataflowLattice AssignmentMap -assignmentLattice = DataflowLattice "assignments for registers" emptyUFM (joinUFM add) - where add _ (OldFact old) (NewFact new) - = case (old, new) of - (NeverOptimize, _) -> (NoChange, NeverOptimize) - (_, NeverOptimize) -> (SomeChange, NeverOptimize) - (xassign2 -> Just (e, e')) - | e == e' -> (NoChange, old) - | otherwise -> (SomeChange, NeverOptimize) - _ -> (SomeChange, NeverOptimize) - --- Deletes sinks from assignment map, because /this/ is the place --- where it will be sunk to. -deleteSinks :: UserOfLocalRegs n => n -> AssignmentMap -> AssignmentMap -deleteSinks n m = foldRegsUsed (adjustUFM f) m n - where f (AlwaysSink _) = NeverOptimize - f old = old - --- Invalidates any expressions that use a register. -invalidateUsersOf :: CmmReg -> AssignmentMap -> AssignmentMap -invalidateUsersOf reg = mapUFM (invalidateUsers' reg) - where invalidateUsers' reg (xassign -> Just e) | reg `regUsedIn` e = NeverOptimize - invalidateUsers' _ old = old - -middleAssignment :: WithRegUsage CmmNode O O -> AssignmentMap -> AssignmentMap - --- Algorithm for annotated assignments: --- 1. Delete any sinking assignments that were used by this instruction --- 2. Add the assignment to our list of valid local assignments with --- the correct optimization policy. --- 3. Look for all assignments that reference that register and --- invalidate them. -middleAssignment n@(AssignLocal r e usage) assign - = invalidateUsersOf (CmmLocal r) . add . deleteSinks n $ assign - where add m = addToUFM m r - $ case usage of - SingleUse -> AlwaysInline e - ManyUse -> decide e - decide CmmLit{} = AlwaysInline e - decide CmmReg{} = AlwaysInline e - decide CmmLoad{} = AlwaysSink e - decide CmmStackSlot{} = AlwaysSink e - decide CmmMachOp{} = AlwaysSink e - decide CmmRegOff{} = AlwaysSink e - --- Algorithm for unannotated assignments of global registers: --- 1. Delete any sinking assignments that were used by this instruction --- 2. Look for all assignments that reference this register and --- invalidate them. -middleAssignment (Plain n@(CmmAssign reg@(CmmGlobal _) _)) assign - = invalidateUsersOf reg . deleteSinks n $ assign - --- Algorithm for unannotated assignments of *local* registers: do --- nothing (it's a reload, so no state should have changed) -middleAssignment (Plain (CmmAssign (CmmLocal _) _)) assign = assign - --- Algorithm for stores: --- 1. Delete any sinking assignments that were used by this instruction --- 2. Look for all assignments that load from memory locations that --- were clobbered by this store and invalidate them. -middleAssignment (Plain n@(CmmStore lhs rhs)) assign - = mapUFM_Directly p . deleteSinks n $ assign - -- ToDo: There's a missed opportunity here: even if a memory - -- access we're attempting to sink gets clobbered at some - -- location, it's still /better/ to sink it to right before the - -- point where it gets clobbered. How might we do this? - -- Unfortunately, it's too late to change the assignment... - where p r (xassign -> Just x) | (lhs, rhs) `clobbers` (r, x) = NeverOptimize - p _ old = old - --- Assumption: Unsafe foreign calls don't clobber memory -middleAssignment (Plain n@(CmmUnsafeForeignCall{})) assign - = foldRegsDefd (\m r -> addToUFM m r NeverOptimize) (deleteSinks n assign) n - -middleAssignment (Plain (CmmComment {})) assign - = assign - --- Assumptions: --- * Stack slots do not overlap with any other memory locations --- * Non stack-slot stores always conflict with each other. (This is --- not always the case; we could probably do something special for Hp) --- * Stack slots for different areas do not overlap --- * Stack slots within the same area and different offsets may --- overlap; we need to do a size check (see 'overlaps'). -clobbers :: (CmmExpr, CmmExpr) -> (Unique, CmmExpr) -> Bool -clobbers (ss@CmmStackSlot{}, CmmReg (CmmLocal r)) (u, CmmLoad (ss'@CmmStackSlot{}) _) - | getUnique r == u, ss == ss' = False -- No-op on the stack slot (XXX: Do we need this special case?) -clobbers (CmmStackSlot (CallArea a) o, rhs) (_, expr) = f expr - where f (CmmLoad (CmmStackSlot (CallArea a') o') t) - = (a, o, widthInBytes (cmmExprWidth rhs)) `overlaps` (a', o', widthInBytes (typeWidth t)) - f (CmmLoad e _) = containsStackSlot e - f (CmmMachOp _ es) = or (map f es) - f _ = False - -- Maybe there's an invariant broken if this actually ever - -- returns True - containsStackSlot (CmmLoad{}) = True -- load of a load, all bets off - containsStackSlot (CmmMachOp _ es) = or (map containsStackSlot es) - containsStackSlot (CmmStackSlot{}) = True - containsStackSlot _ = False -clobbers _ (_, e) = f e - where f (CmmLoad (CmmStackSlot _ _) _) = False - f (CmmLoad{}) = True -- conservative - f (CmmMachOp _ es) = or (map f es) - f _ = False - --- Check for memory overlapping. --- Diagram: --- 4 8 12 --- s -w- o --- [ I32 ] --- [ F64 ] --- s' -w'- o' -type CallSubArea = (AreaId, Int, Int) -- area, offset, width -overlaps :: CallSubArea -> CallSubArea -> Bool -overlaps (a, _, _) (a', _, _) | a /= a' = False -overlaps (_, o, w) (_, o', w') = - let s = o - w - s' = o' - w' - in (s' < o) && (s < o) -- Not LTE, because [ I32 ][ I32 ] is OK - -lastAssignment :: WithRegUsage CmmNode O C -> AssignmentMap -> [(Label, AssignmentMap)] --- Variables are dead across calls, so invalidating all mappings is justified -lastAssignment (Plain (CmmCall _ (Just k) _ _ _)) assign = [(k, mapUFM (const NeverOptimize) assign)] -lastAssignment (Plain (CmmForeignCall {succ=k})) assign = [(k, mapUFM (const NeverOptimize) assign)] -lastAssignment l assign = map (\id -> (id, assign)) $ successors l - -assignmentTransfer :: FwdTransfer (WithRegUsage CmmNode) AssignmentMap -assignmentTransfer = mkFTransfer3 (flip const) middleAssignment ((mkFactBase assignmentLattice .) . lastAssignment) - -assignmentRewrite :: FwdRewrite FuelUniqSM (WithRegUsage CmmNode) AssignmentMap -assignmentRewrite = mkFRewrite3 first middle last - where - first _ _ = return Nothing - middle (Plain m) assign = return $ rewrite assign (precompute assign m) mkMiddle m - middle _ _ = return Nothing - last (Plain l) assign = return $ rewrite assign (precompute assign l) mkLast l - -- Tuple is (inline?, reloads) - precompute assign n = foldRegsUsed f (False, []) n -- duplicates are harmless - where f (i, l) r = case lookupUFM assign r of - Just (AlwaysSink e) -> (i, (Plain (CmmAssign (CmmLocal r) e)):l) - Just (AlwaysInline _) -> (True, l) - Just NeverOptimize -> (i, l) - -- This case can show up when we have - -- limited optimization fuel. - Nothing -> (i, l) - rewrite _ (False, []) _ _ = Nothing - -- Note [CmmCall Inline Hack] - -- ToDo: Conservative hack: don't do any inlining on CmmCalls, since - -- the code produced here tends to be unproblematic and I need - -- to write lint passes to ensure that we don't put anything in - -- the arguments that could be construed as a global register by - -- some later translation pass. (For example, slots will turn - -- into dereferences of Sp). This is the same hack in spirit as - -- was in cmm/CmmOpt.hs. Fix this up to only bug out if certain - -- CmmExprs are involved. - -- ToDo: We miss an opportunity here, where all possible - -- inlinings should instead be sunk. - rewrite _ (True, []) _ n | not (inlinable n) = Nothing -- see [CmmCall Inline Hack] - rewrite assign (i, xs) mk n = Just $ mkMiddles xs <*> mk (Plain (inline i assign n)) - - inline :: Bool -> AssignmentMap -> CmmNode e x -> CmmNode e x - inline False _ n = n - inline True _ n | not (inlinable n) = n -- see [CmmCall Inline Hack] - inline True assign n = mapExpDeep inlineExp n - where inlineExp old@(CmmReg (CmmLocal r)) - = case lookupUFM assign r of - Just (AlwaysInline x) -> x - _ -> old - inlineExp old@(CmmRegOff (CmmLocal r) i) - = case lookupUFM assign r of - Just (AlwaysInline x) -> CmmMachOp (MO_Add rep) [x, CmmLit (CmmInt (fromIntegral i) rep)] - where rep = typeWidth (localRegType r) - _ -> old - inlineExp old = old - - inlinable :: CmmNode e x -> Bool - inlinable (CmmCall{}) = False - inlinable (CmmForeignCall{}) = False - inlinable _ = True - -rewriteAssignments :: CmmGraph -> FuelUniqSM CmmGraph -rewriteAssignments g = do - g' <- annotateUsage g - g'' <- liftM fst $ dataflowPassFwd g' [(g_entry g, fact_bot assignmentLattice)] $ - analRewFwd assignmentLattice assignmentTransfer assignmentRewrite - return (modifyGraph eraseRegUsage g'') --------------------- -- prettyprinting @@ -605,7 +305,11 @@ instance Outputable DualLive where if isEmptyUniqSet stack then PP.empty else (ppr_regs "live on stack =" stack)] --- ToDo: Outputable instance for UsageMap and AssignmentMap +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 -- 1.7.10.4