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 Outputable ( showSDoc, ppr, nest )
31 -- Create a new internal var with the given name and type. A Unique is
32 -- appended to the given name, to ensure uniqueness (not strictly neccesary,
33 -- since the Unique is also stored in the name, but this ensures variable
34 -- names are unique in the output).
35 mkInternalVar :: String -> Type.Type -> TransformMonad Var.Var
36 mkInternalVar str ty = do
38 let occname = OccName.mkVarOcc (str ++ show uniq)
39 let name = Name.mkInternalName uniq occname SrcLoc.noSrcSpan
40 return $ Var.mkLocalIdVar name ty IdInfo.vanillaIdInfo
42 -- Apply the given transformation to all expressions in the given expression,
43 -- including the expression itself.
44 everywhere :: (String, Transform) -> Transform
45 everywhere trans = applyboth (subeverywhere (everywhere trans)) trans
47 -- Apply the first transformation, followed by the second transformation, and
48 -- keep applying both for as long as expression still changes.
49 applyboth :: Transform -> (String, Transform) -> Transform
50 applyboth first (name, second) expr = do
54 (expr'', changed) <- Writer.listen $ second expr'
55 if Monoid.getAny changed
57 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" ) $
58 applyboth first (name, second) expr''
62 -- Apply the given transformation to all direct subexpressions (only), not the
64 subeverywhere :: Transform -> Transform
65 subeverywhere trans (App a b) = do
70 subeverywhere trans (Let (Rec binds) expr) = do
72 binds' <- mapM transbind binds
73 return $ Let (Rec binds') expr'
75 transbind :: (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr)
80 subeverywhere trans (Lam x expr) = do
84 subeverywhere trans (Case scrut b t alts) = do
86 alts' <- mapM transalt alts
87 return $ Case scrut' b t alts'
89 transalt :: CoreAlt -> TransformMonad CoreAlt
90 transalt (con, binders, expr) = do
92 return (con, binders, expr')
95 subeverywhere trans expr = return expr
97 -- Apply the given transformation to all expressions, except for every first
98 -- argument of an application.
99 notapplied :: (String, Transform) -> Transform
100 notapplied trans = applyboth (subnotapplied trans) trans
102 -- Apply the given transformation to all (direct and indirect) subexpressions
103 -- (but not the expression itself), except for the first argument of an
104 -- applicfirst argument of an application
105 subnotapplied :: (String, Transform) -> Transform
106 subnotapplied trans (App a b) = do
107 a' <- subnotapplied trans a
108 b' <- notapplied trans b
111 -- Let subeverywhere handle all other expressions
112 subnotapplied trans expr = subeverywhere (notapplied trans) expr
114 -- Run the given transforms over the given expression
115 dotransforms :: [Transform] -> UniqSupply.UniqSupply -> CoreExpr -> CoreExpr
116 dotransforms transs uniqSupply = (flip State.evalState initState) . (dotransforms' transs)
117 where initState = TransformState uniqSupply
119 -- Runs each of the transforms repeatedly inside the State monad.
120 dotransforms' :: [Transform] -> CoreExpr -> State.State TransformState CoreExpr
121 dotransforms' transs expr = do
122 (expr', changed) <- Writer.runWriterT $ Monad.foldM (flip ($)) expr transs
123 if Monoid.getAny changed then dotransforms' transs expr' else return expr'
125 -- Sets the changed flag in the TransformMonad, to signify that some
126 -- transform has changed the result
127 setChanged :: TransformMonad ()
128 setChanged = Writer.tell (Monoid.Any True)
130 -- Sets the changed flag and returns the given value.
131 change :: a -> TransformMonad a
136 -- Create a new Unique
137 mkUnique :: TransformMonad Unique.Unique
138 mkUnique = Trans.lift $ do
139 us <- getA tsUniqSupply
140 let (us', us'') = UniqSupply.splitUniqSupply us
141 putA tsUniqSupply us'
142 return $ UniqSupply.uniqFromSupply us''