-{-# LANGUAGE GADTs,NoMonoLocalBinds #-}
+{-# LANGUAGE GADTs, NoMonoLocalBinds, FlexibleContexts, ViewPatterns #-}
-- 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
--, insertSpillsAndReloads --- XXX todo check live-in at entry against formals
, dualLivenessWithInsertion
- , availRegsLattice
- , cmmAvailableReloads
- , insertLateReloads
+ , rewriteAssignments
, removeDeadAssignmentsAndReloads
)
where
import Outputable hiding (empty)
import qualified Outputable as PP
import UniqSet
+import UniqFM
+import Unique
-import Compiler.Hoopl
+import Compiler.Hoopl hiding (Unique)
import Data.Maybe
import Prelude hiding (succ, zip)
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
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
-- 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
+-- foldUFM_Directly :: (Unique -> elt -> a -> a) -> a -> UniqFM elt -> a
+invalidateUsersOf reg m = foldUFM_Directly f m m -- [foldUFM performance]
+ where f u (xassign -> Just e) m | reg `regUsedIn` e = addToUFM_Directly m u NeverOptimize
+ f _ _ m = m
+{- This requires the entire spine of the map to be continually rebuilt,
+ - which causes crazy memory usage!
+invalidateUsersOf reg = mapUFM (invalidateUsers' reg)
+ where invalidateUsers' reg (xassign -> Just e) | reg `regUsedIn` e = NeverOptimize
+ invalidateUsers' _ old = old
+-}
+
+-- Note [foldUFM performance]
+-- These calls to fold UFM no longer leak memory, but they do cause
+-- pretty killer amounts of allocation. So they'll be something to
+-- optimize; we need an algorithmic change to prevent us from having to
+-- traverse the /entire/ map continually.
+
+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
+ = let m = deleteSinks n assign
+ in foldUFM_Directly f m m -- [foldUFM performance]
+ where f u (xassign -> Just x) m | (lhs, rhs) `clobbers` (u, x) = addToUFM_Directly m u NeverOptimize
+ f _ _ m = m
+{- Also leaky
+ = 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, deleteSinks l 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
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 "<everything available>"
- else ppr_regs "available = all but" s
- ppr (AvailRegs s) = if isEmptyUniqSet s then text "<nothing available>"
- else ppr_regs "available = " s
+-- ToDo: Outputable instance for UsageMap and AssignmentMap
my_trace :: String -> SDoc -> a -> a
my_trace = if False then pprTrace else \_ _ a -> a
projects / ghc-hetmet.git / commitdiff