tock-mirror/transformations/SimplifyProcs.hs
Neil Brown 8f767ff0d4 Made all the imports of Data.Generics have an import list
This makes sure that we catch all leftover instances of using SYB to do generic operations that we should be using Polyplate for instead.  Most modules should only import Data, and possibly Typeable.
2009-04-09 15:36:37 +00:00

223 lines
10 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/>.
-}
-- | Simplify processes.
module SimplifyProcs (simplifyProcs, fixLowReplicators) where
import Control.Monad.State
import Data.Generics (Data)
import qualified Data.Set as Set
import qualified AST as A
import CompState
import EvalConstants
import EvalLiterals
import Metadata
import Pass
import qualified Properties as Prop
import Traversal
import Types
import Utils
simplifyProcs :: [Pass A.AST]
simplifyProcs =
[ parsToProcs
, removeParAssign
, flattenAssign
]
-- | Wrap the subprocesses of PARs in no-arg PROCs.
parsToProcs :: PassOn A.Process
parsToProcs = pass "Wrap PAR subprocesses in PROCs"
[Prop.parUsageChecked]
[Prop.parsWrapped]
(applyBottomUpM doProcess)
where
doProcess :: A.Process -> PassM A.Process
doProcess (A.Par m pm s)
= do s' <- doStructured s
return $ A.Par m pm s'
doProcess p = return p
-- FIXME This should be generic and in Pass.
doStructured :: A.Structured A.Process -> PassM (A.Structured A.Process)
doStructured = transformOnly wrapProcess
where
wrapProcess m p
= do s@(A.Specification _ n _) <- makeNonceProc m p
modify (\cs -> cs { csParProcs = Set.insert n (csParProcs cs) })
return $ A.Spec m s (A.Only m (A.ProcCall m n []))
-- | Turn parallel assignment into multiple single assignments through temporaries.
removeParAssign :: PassOn A.Process
removeParAssign = pass "Remove parallel assignment"
[Prop.parUsageChecked, Prop.functionsRemoved, Prop.functionCallsRemoved]
[Prop.assignParRemoved]
(applyBottomUpM doProcess)
where
doProcess :: A.Process -> PassM A.Process
doProcess (A.Assign m vs@(_:_:_) (A.ExpressionList _ es))
= do ts <- mapM astTypeOf vs
specs <- sequence [makeNonceVariable "assign_temp" m t A.Original | t <- ts]
let temps = [A.Variable m n | A.Specification _ n _ <- specs]
let first = [A.Assign m [v] (A.ExpressionList m [e]) | (v, e) <- zip temps es]
let second = [A.Assign m [v] (A.ExpressionList m [A.ExprVariable m v']) | (v, v') <- zip vs temps]
return $ A.Seq m $ foldl (\s spec -> A.Spec m spec s) (A.Several m (map (A.Only m) (first ++ second))) specs
doProcess p = return p
-- | Turn assignment of arrays and records into multiple assignments.
flattenAssign :: PassOnOps (ExtOpMSP BaseOp `ExtOpMP` A.Process)
flattenAssign = pass "Flatten assignment"
(Prop.agg_typesDone ++ [Prop.assignParRemoved])
[Prop.assignFlattened]
(makeRecurseM ops)
where
ops = baseOp `extOpMS` (ops, makeBottomUpM ops doStructured)
`extOpM` makeBottomUpM ops doProcess
doProcess :: A.Process -> PassM A.Process
doProcess (A.Assign m [v] (A.ExpressionList m' [e]))
= do t <- astTypeOf v
assign m t v m' e
doProcess p = return p
doStructured :: Data a => A.Structured a -> PassM (A.Structured a)
doStructured (A.Spec m (A.Specification m' n t@(A.RecordType _ _ fs)) s)
= do procSpec <- recordCopyProc n m fs
return $ A.Spec m (A.Specification m' n t) (procSpec s)
doStructured s = return s
assign :: Meta -> A.Type -> A.Variable -> Meta -> A.Expression -> PassM A.Process
assign m t@(A.Array _ _) v m' e = complexAssign m t v m' e
assign m t@(A.Record _) v m' e = complexAssign m t v m' e
assign m _ v m' e = return $ A.Assign m [v] (A.ExpressionList m' [e])
makeCopyProcName :: A.Name -> PassM A.Name
makeCopyProcName n = do file <- getCompState >>* csCurrentFile
let m = Meta (Just file) 0 0
return $ n {A.nameName = "copy_" ++ mungeMeta m ++ A.nameName n}
complexAssign :: Meta -> A.Type -> A.Variable -> Meta -> A.Expression -> PassM A.Process
complexAssign m t v m' e
= do -- Abbreviate the source and destination, to avoid doing the
-- subscript each time.
destAM <- liftM makeAbbrevAM $ abbrevModeOfVariable v
dest@(A.Specification _ destN _) <-
makeNonceIs "assign_dest" m t destAM v
let destV = A.Variable m destN
src@(A.Specification _ srcN _) <-
makeNonceIsExpr "assign_src" m' t e
let srcV = A.Variable m' srcN
body <- case t of
A.Array (d:_) _ ->
-- Array assignments become a loop with an assignment
-- inside.
do counter <- makeNonceCounter "i" m
let zero = A.Literal m A.Int $ A.IntLiteral m "0"
limit = case d of
A.UnknownDimension -> A.ExprVariable m $ specificDimSize 0 srcV
A.Dimension e -> e
rep = A.For m zero limit (makeConstant m 1)
itemT <- trivialSubscriptType m t
-- Don't need to check bounds, as we'll always be within bounds
let sub = A.Subscript m A.NoCheck (A.ExprVariable m
(A.Variable m counter))
inner <- assign m itemT
(A.SubscriptedVariable m sub destV) m'
(A.ExprVariable m'
(A.SubscriptedVariable m' sub srcV))
return $ A.Spec m (A.Specification m counter (A.Rep m rep)) $ A.Only m inner
A.Record n -> makeCopyProcName n >>= \n' ->
return $ A.Only m $ A.ProcCall m n'
[A.ActualVariable destV, A.ActualVariable srcV]
return $ A.Seq m $ A.Spec m src $ A.Spec m dest body
-- TODO could make this a separate pass if we wanted (to be run first)
recordCopyProc :: Data a => A.Name -> Meta -> [(A.Name, A.Type)] -> PassM (A.Structured a -> A.Structured a)
recordCopyProc n m fs
-- Record assignments become a sequence of
-- assignments, one for each field.
= do let t = A.Record n
(A.Specification _ nonceLHS _) <- makeNonceVariable "record_copy_arg" m t A.Abbrev
let destV = A.Variable m nonceLHS
(A.Specification _ nonceRHS _) <- makeNonceVariable "record_copy_arg" m t A.ValAbbrev
let srcV = A.Variable m nonceRHS
assigns <-
sequence [do let sub = A.SubscriptField m fName
assign m fType
(A.SubscriptedVariable m sub destV) m
(A.ExprVariable m
(A.SubscriptedVariable m sub srcV))
| (fName, fType) <- fs]
n' <- makeCopyProcName n
let code = A.Seq m $ A.Several m $ map (A.Only m) assigns
proc = A.Proc m (A.InlineSpec, A.PlainRec)
[A.Formal A.Abbrev t nonceLHS, A.Formal A.ValAbbrev t nonceRHS]
(Just code)
defineName n' $ A.NameDef {
A.ndMeta = m,
A.ndName = A.nameName n',
A.ndOrigName = A.nameName n',
A.ndSpecType = proc,
A.ndAbbrevMode = A.Original,
A.ndNameSource = A.NameNonce,
A.ndPlacement = A.Unplaced
}
return (A.Spec m (A.Specification m n' proc))
-- | Removes replicators with a replicator count of zero,
-- and transforms replicators with a replicator count of one.
--
-- We don't currently transform replicators in array constructors,
-- just replicators in SEQ, PAR, ALT, IF.
--
-- This pass is primarily to make sure that PAR replicators with 0 or 1 counts
-- pass the usage checking, but it doesn't hurt to remove any redundant code (or
-- simplify code) in the other replicators.
fixLowReplicators :: PassOn A.Process
fixLowReplicators = pass "Fix low-count (0, 1) replicators" [] []
(applyBottomUpM doProcess)
where
doProcess :: Transform A.Process
doProcess (A.Seq m s) = doStructured s >>* A.Seq m
doProcess (A.Par m p s) = doStructured s >>* A.Par m p
doProcess (A.If m s) = doStructured s >>* A.If m
doProcess (A.Alt m p s) = doStructured s >>* A.Alt m p
doProcess p = return p
doStructured :: Data a => Transform (A.Structured a)
doStructured s@(A.Only {}) = return s
doStructured (A.Several m ss) = mapM doStructured ss >>* A.Several m
doStructured (A.ProcThen m p s) = doStructured s >>* A.ProcThen m p
doStructured (A.Spec m sp@(A.Specification m' n (A.Rep m''
(A.For m''' begin end _))) s)
| isConstant end
= do endVal <- evalIntExpression end
case endVal of
0 -> return $ A.Several m []
1 -> doStructured s >>*
A.Spec m (A.Specification m' n
(A.Is m'' A.ValAbbrev A.Int $ A.ActualExpression begin))
_ -> doStructured s >>* A.Spec m sp
doStructured (A.Spec m sp s) = doStructured s >>* A.Spec m sp