1 {-# LANGUAGE PackageImports #-}
3 -- This module provides functions for program transformations.
5 module NormalizeTools where
8 import qualified Data.Monoid as Monoid
9 import qualified Control.Monad as Monad
10 import qualified Control.Monad.Trans.State as State
11 import qualified Control.Monad.Trans.Writer as Writer
12 import qualified "transformers" Control.Monad.Trans as Trans
17 import qualified UniqSupply
18 import qualified Unique
19 import qualified OccName
22 import qualified SrcLoc
24 import qualified IdInfo
25 import qualified CoreUtils
26 import qualified CoreSubst
27 import Outputable ( showSDoc, ppr, nest )
32 -- Create a new internal var with the given name and type. A Unique is
33 -- appended to the given name, to ensure uniqueness (not strictly neccesary,
34 -- since the Unique is also stored in the name, but this ensures variable
35 -- names are unique in the output).
36 mkInternalVar :: String -> Type.Type -> TransformMonad Var.Var
37 mkInternalVar str ty = do
39 let occname = OccName.mkVarOcc (str ++ show uniq)
40 let name = Name.mkInternalName uniq occname SrcLoc.noSrcSpan
41 return $ Var.mkLocalIdVar name ty IdInfo.vanillaIdInfo
43 -- Apply the given transformation to all expressions in the given expression,
44 -- including the expression itself.
45 everywhere :: (String, Transform) -> Transform
46 everywhere trans = applyboth (subeverywhere (everywhere trans)) trans
48 -- Apply the first transformation, followed by the second transformation, and
49 -- keep applying both for as long as expression still changes.
50 applyboth :: Transform -> (String, Transform) -> Transform
51 applyboth first (name, second) expr = do
55 (expr'', changed) <- Writer.listen $ second expr'
56 if Monoid.getAny changed
58 trace ("Transform " ++ name ++ " changed from:\n" ++ showSDoc (nest 4 $ ppr expr') ++ "\nType: \n" ++ (showSDoc $ nest 4 $ ppr $ CoreUtils.exprType expr') ++ "\n" ++ "\nTo:\n" ++ showSDoc (nest 4 $ ppr expr'') ++ "\n" ++ "Type: \n" ++ (showSDoc $ nest 4 $ ppr $ CoreUtils.exprType expr'') ++ "\n" ) $
59 applyboth first (name, second) expr''
63 -- Apply the given transformation to all direct subexpressions (only), not the
65 subeverywhere :: Transform -> Transform
66 subeverywhere trans (App a b) = do
71 subeverywhere trans (Let (Rec binds) expr) = do
73 binds' <- mapM transbind binds
74 return $ Let (Rec binds') expr'
76 transbind :: (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
81 subeverywhere trans (Lam x expr) = do
85 subeverywhere trans (Case scrut b t alts) = do
87 alts' <- mapM transalt alts
88 return $ Case scrut' b t alts'
90 transalt :: CoreAlt -> TransformMonad CoreAlt
91 transalt (con, binders, expr) = do
93 return (con, binders, expr')
96 subeverywhere trans expr = return expr
98 -- Apply the given transformation to all expressions, except for every first
99 -- argument of an application.
100 notapplied :: (String, Transform) -> Transform
101 notapplied trans = applyboth (subnotapplied trans) trans
103 -- Apply the given transformation to all (direct and indirect) subexpressions
104 -- (but not the expression itself), except for the first argument of an
105 -- applicfirst argument of an application
106 subnotapplied :: (String, Transform) -> Transform
107 subnotapplied trans (App a b) = do
108 a' <- subnotapplied trans a
109 b' <- notapplied trans b
112 -- Let subeverywhere handle all other expressions
113 subnotapplied trans expr = subeverywhere (notapplied trans) expr
115 -- Run the given transforms over the given expression
116 dotransforms :: [Transform] -> UniqSupply.UniqSupply -> CoreExpr -> CoreExpr
117 dotransforms transs uniqSupply = (flip State.evalState initState) . (dotransforms' transs)
118 where initState = TransformState uniqSupply
120 -- Runs each of the transforms repeatedly inside the State monad.
121 dotransforms' :: [Transform] -> CoreExpr -> State.State TransformState CoreExpr
122 dotransforms' transs expr = do
123 (expr', changed) <- Writer.runWriterT $ Monad.foldM (flip ($)) expr transs
124 if Monoid.getAny changed then dotransforms' transs expr' else return expr'
126 -- Sets the changed flag in the TransformMonad, to signify that some
127 -- transform has changed the result
128 setChanged :: TransformMonad ()
129 setChanged = Writer.tell (Monoid.Any True)
131 -- Sets the changed flag and returns the given value.
132 change :: a -> TransformMonad a
137 -- Create a new Unique
138 mkUnique :: TransformMonad Unique.Unique
139 mkUnique = Trans.lift $ do
140 us <- getA tsUniqSupply
141 let (us', us'') = UniqSupply.splitUniqSupply us
142 putA tsUniqSupply us'
143 return $ UniqSupply.uniqFromSupply us''
145 -- Replace each of the binders given with the coresponding expressions in the
147 substitute :: [(CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
148 substitute replace expr = CoreSubst.substExpr subs expr
149 where subs = foldl (\s (b, e) -> CoreSubst.extendIdSubst s b e) CoreSubst.emptySubst replace