tock-mirror/transformations/Unnest.hs
Adam Sampson 6debf9292f Rework Traversal, and convert all passes to use it.
This changes the Traversal API to the one that I've been working on in
the Polyplate branch, but implemented in terms of Data. The
performance isn't as good as the Polyplate version, but the code is a
lot simpler because it doesn't need all the type constraints (and it
doesn't make GHC struggle).

This also reworks all the passes in Tock to use the new API, including
those that previously used makeGeneric (which I've now removed) or
everywhereM. Most of the passes are simpler because of this, and I
suspect it's fixed a few subtle bugs resulting from missing recursion
in makeGeneric code.

I haven't yet profiled this, but subjectively it seems about the same
as the old Traversal (and thus faster for all the passes that didn't
yet use it).
2008-05-25 20:13:57 +00:00

201 lines
7.8 KiB
Haskell

{-
Tock: a compiler for parallel languages
Copyright (C) 2007, 2008 University of Kent
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program. If not, see <http://www.gnu.org/licenses/>.
-}
-- | Flatten nested declarations.
module Unnest (unnest) where
import Control.Monad.Identity
import Control.Monad.State
import Data.Generics
import Data.List
import qualified Data.Map as Map
import Data.Maybe
import qualified AST as A
import CompState
import Errors
import EvalConstants
import Metadata
import Pass
import qualified Properties as Prop
import Traversal
import Types
unnest :: [Pass]
unnest = makePassesDep
[ ("Convert free names to arguments", removeFreeNames, [Prop.mainTagged, Prop.parsWrapped, Prop.functionCallsRemoved], [Prop.freeNamesToArgs])
, ("Pull nested definitions to top level", removeNesting, [Prop.freeNamesToArgs], [Prop.nestedPulled])
]
type NameMap = Map.Map String A.Name
-- | Get the set of free names within a block of code.
freeNamesIn :: Data t => t -> NameMap
freeNamesIn = doGeneric
`extQ` (ignore :: String -> NameMap)
`extQ` (ignore :: Meta -> NameMap)
`extQ` doName `ext1Q` doStructured `extQ` doSpecType
where
doGeneric :: Data t => t -> NameMap
doGeneric n = Map.unions $ gmapQ freeNamesIn n
ignore :: t -> NameMap
ignore s = Map.empty
doName :: A.Name -> NameMap
doName n | ghostVarPrefix `isPrefixOf` (A.nameName n)
&& ghostVarSuffix `isSuffixOf` (A.nameName n) = Map.empty
| otherwise = Map.singleton (A.nameName n) n
doStructured :: Data a => A.Structured a -> NameMap
doStructured (A.Rep _ rep s) = doRep rep s
doStructured (A.Spec _ spec s) = doSpec spec s
doStructured s = doGeneric s
doSpec :: Data t => A.Specification -> t -> NameMap
doSpec (A.Specification _ n st) child
= Map.union fns $ Map.delete (A.nameName n) $ freeNamesIn child
where
fns = freeNamesIn st
doRep :: Data t => A.Replicator -> t -> NameMap
doRep rep child
= Map.union fns $ Map.delete (A.nameName repName) $ freeNamesIn child
where
(repName, fns) = case rep of
A.For _ n b c -> (n, Map.union (freeNamesIn b) (freeNamesIn c))
A.ForEach _ n b -> (n, freeNamesIn b)
doSpecType :: A.SpecType -> NameMap
doSpecType (A.Proc _ _ fs p) = Map.difference (freeNamesIn p) (freeNamesIn fs)
doSpecType (A.Function _ _ _ fs vp) = Map.difference (freeNamesIn vp) (freeNamesIn fs)
doSpecType st = doGeneric st
-- | Replace names.
replaceNames :: Data t => [(A.Name, A.Name)] -> t -> t
replaceNames map v = runIdentity $ applyDepthM doName v
where
smap = Map.fromList [(A.nameName f, t) | (f, t) <- map]
doName :: A.Name -> Identity A.Name
doName n = return $ Map.findWithDefault n (A.nameName n) smap
-- | Turn free names in PROCs into arguments.
removeFreeNames :: PassType
removeFreeNames = applyDepthM2 doSpecification doProcess
where
doSpecification :: A.Specification -> PassM A.Specification
doSpecification spec = case spec of
A.Specification m n st@(A.Proc mp sm fs p) ->
do -- If this is the top-level process, we shouldn't add new args --
-- we know it's not going to be moved by removeNesting, so anything
-- that it had in scope originally will still be in scope.
ps <- get
when (null $ csMainLocals ps) (dieReport (Nothing,"No main process found"))
let isTLP = (snd $ head $ csMainLocals ps) == n
-- Figure out the free names.
let freeNames' = if isTLP then [] else Map.elems $ freeNamesIn st
let freeNames'' = [n | n <- freeNames',
case A.nameType n of
A.ChannelName -> True
A.PortName -> True
A.TimerName -> True
A.VariableName -> True
_ -> False]
-- Don't bother with constants -- they get pulled up anyway.
freeNames <- filterM (liftM not . isConstantName) freeNames''
types <- mapM astTypeOf freeNames
origAMs <- mapM abbrevModeOfName freeNames
let ams = map makeAbbrevAM origAMs
-- Generate and define new names to replace them with
newNamesS <- sequence [makeNonce (A.nameName n) | n <- freeNames]
let newNames = [on { A.nameName = nn } | (on, nn) <- zip freeNames newNamesS]
onds <- mapM (\n -> lookupNameOrError n $ dieP mp $ "Could not find recorded type for free name: " ++ (show $ A.nameName n)) freeNames
sequence_ [defineName nn (ond { A.ndName = A.nameName nn,
A.ndAbbrevMode = am })
| (ond, nn, am) <- zip3 onds newNames ams]
-- Add formals for each of the free names
let newFs = [A.Formal am t n | (am, t, n) <- zip3 ams types newNames]
let st' = A.Proc mp sm (fs ++ newFs) $ replaceNames (zip freeNames newNames) p
let spec' = A.Specification m n st'
-- Update the definition of the proc
nameDef <- lookupName n
defineName n (nameDef { A.ndSpecType = st' })
-- Note that we should add extra arguments to calls of this proc
-- when we find them
let newAs = [case am of
A.Abbrev -> A.ActualVariable (A.Variable m n)
_ -> A.ActualExpression (A.ExprVariable m (A.Variable m n))
| (am, n) <- zip ams freeNames]
debug $ "removeFreeNames: " ++ show n ++ " has new args " ++ show newAs
when (newAs /= []) $
modify $ (\ps -> ps { csAdditionalArgs = Map.insert (A.nameName n) newAs (csAdditionalArgs ps) })
return spec'
_ -> return spec
-- | Add the extra arguments we recorded when we saw the definition.
doProcess :: A.Process -> PassM A.Process
doProcess p@(A.ProcCall m n as)
= do st <- get
case Map.lookup (A.nameName n) (csAdditionalArgs st) of
Just add -> return $ A.ProcCall m n (as ++ add)
Nothing -> return p
doProcess p = return p
-- | Pull nested declarations to the top level.
removeNesting :: Data t => Transform (A.Structured t)
removeNesting s
= do pushPullContext
s' <- (makeRecurse ops) s >>= applyPulled
popPullContext
return s'
where
ops :: Ops
ops = baseOp `extOpS` doStructured
recurse :: Recurse
recurse = makeRecurse ops
descend :: Descend
descend = makeDescend ops
doStructured :: Data t => Transform (A.Structured t)
doStructured s@(A.Spec m spec subS)
= do spec'@(A.Specification _ n st) <- recurse spec
isConst <- isConstantName n
if isConst || canPull st then
do debug $ "removeNesting: pulling up " ++ show n
addPulled $ (m, Left spec')
doStructured subS
else descend s
doStructured s = descend s
canPull :: A.SpecType -> Bool
canPull (A.Proc _ _ _ _) = True
canPull (A.RecordType _ _ _) = True
canPull (A.Protocol _ _) = True
canPull (A.ProtocolCase _ _) = True
canPull _ = False