Add Cast propagation transform.

[matthijs/master-project/cλash.git] / NormalizeTools.hs

diff --git a/NormalizeTools.hs b/NormalizeTools.hs
index c36d85f2006f54aa84632c54afb4a9f40ce45efb..8e57ba8f2ec2446301ebcf22ec83e03f577470b7 100644 (file)
--- a/NormalizeTools.hs
+++ b/NormalizeTools.hs
@@ -7,6 +7,7 @@ module NormalizeTools where
 import Debug.Trace
 import qualified List
 import qualified Data.Monoid as Monoid
 import Debug.Trace
 import qualified List
 import qualified Data.Monoid as Monoid

+import qualified Control.Arrow as Arrow

 import qualified Control.Monad as Monad
 import qualified Control.Monad.Trans.State as State
 import qualified Control.Monad.Trans.Writer as Writer
 import qualified Control.Monad as Monad
 import qualified Control.Monad.Trans.State as State
 import qualified Control.Monad.Trans.Writer as Writer


@@ -74,6 +75,17 @@ cloneVar v = do
   -- contains, but vannillaIdInfo is always correct, since it means "no info").
   return $ Var.lazySetVarIdInfo (Var.setVarUnique v uniq) IdInfo.vanillaIdInfo
 
   -- contains, but vannillaIdInfo is always correct, since it means "no info").
   return $ Var.lazySetVarIdInfo (Var.setVarUnique v uniq) IdInfo.vanillaIdInfo
 

+-- Creates a new function with the same name as the given binder (but with a
+-- new unique) and with the given function body. Returns the new binder for
+-- this function.
+mkFunction :: CoreBndr -> CoreExpr -> TransformMonad CoreBndr
+mkFunction bndr body = do
+  let ty = CoreUtils.exprType body
+  id <- cloneVar bndr
+  let newid = Var.setVarType id ty
+  Trans.lift $ addGlobalBind newid body
+  return newid
+

 -- Apply the given transformation to all expressions in the given expression,
 -- including the expression itself.
 everywhere :: (String, Transform) -> Transform
 -- Apply the given transformation to all expressions in the given expression,
 -- including the expression itself.
 everywhere :: (String, Transform) -> Transform


@@ -130,26 +142,33 @@ subeverywhere trans (Case scrut b t alts) = do
     transalt (con, binders, expr) = do
       expr' <- trans expr
       return (con, binders, expr')
     transalt (con, binders, expr) = do
       expr' <- trans expr
       return (con, binders, expr')

-      

 
 

-subeverywhere trans expr = return expr
+subeverywhere trans (Var x) = return $ Var x
+subeverywhere trans (Lit x) = return $ Lit x
+subeverywhere trans (Type x) = return $ Type x
+
+subeverywhere trans (Cast expr ty) = do
+  expr' <- trans expr
+  return $ Cast expr' ty

 
 

--- Apply the given transformation to all expressions, except for every first
--- argument of an application.
-notapplied :: (String, Transform) -> Transform
-notapplied trans = applyboth (subnotapplied trans) trans
+subeverywhere trans expr = error $ "NormalizeTools.subeverywhere Unsupported expression: " ++ show expr
+
+-- Apply the given transformation to all expressions, except for direct
+-- arguments of an application
+notappargs :: (String, Transform) -> Transform
+notappargs trans = applyboth (subnotappargs trans) trans

 
 -- Apply the given transformation to all (direct and indirect) subexpressions
 
 -- Apply the given transformation to all (direct and indirect) subexpressions

--- (but not the expression itself), except for the first argument of an
--- applicfirst argument of an application
-subnotapplied :: (String, Transform) -> Transform
-subnotapplied trans (App a b) = do
-  a' <- subnotapplied trans a
-  b' <- notapplied trans b
+-- (but not the expression itself), except for direct arguments of an
+-- application
+subnotappargs :: (String, Transform) -> Transform
+subnotappargs trans (App a b) = do
+  a' <- subnotappargs trans a
+  b' <- subnotappargs trans b

   return $ App a' b'
 
 -- Let subeverywhere handle all other expressions
   return $ App a' b'
 
 -- Let subeverywhere handle all other expressions

-subnotapplied trans expr = subeverywhere (notapplied trans) expr
+subnotappargs trans expr = subeverywhere (notappargs trans) expr

 
 -- Runs each of the transforms repeatedly inside the State monad.
 dotransforms :: [Transform] -> CoreExpr -> TransformSession CoreExpr
 
 -- Runs each of the transforms repeatedly inside the State monad.
 dotransforms :: [Transform] -> CoreExpr -> TransformSession CoreExpr


@@ -191,8 +210,21 @@ mkUnique = Trans.lift $ do
 -- Replace each of the binders given with the coresponding expressions in the
 -- given expression.
 substitute :: [(CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
 -- Replace each of the binders given with the coresponding expressions in the
 -- given expression.
 substitute :: [(CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr

-substitute replace expr = CoreSubst.substExpr subs expr
-    where subs = foldl (\s (b, e) -> CoreSubst.extendSubst s b e) CoreSubst.emptySubst replace
+substitute [] expr = expr
+-- Apply one substitution on the expression, but also on any remaining
+-- substitutions. This seems to be the only way to handle substitutions like
+-- [(b, c), (a, b)]. This means we reuse a substitution, which is not allowed
+-- according to CoreSubst documentation (but it doesn't seem to be a problem).
+-- TODO: Find out how this works, exactly.
+substitute ((b, e):subss) expr = substitute subss' expr'
+  where 
+    -- Create the Subst
+    subs = (CoreSubst.extendSubst CoreSubst.emptySubst b e)
+    -- Apply this substitution to the main expression
+    expr' = CoreSubst.substExpr subs expr
+    -- Apply this substitution on all the expressions in the remaining
+    -- substitutions
+    subss' = map (Arrow.second (CoreSubst.substExpr subs)) subss

 
 -- Run a given TransformSession. Used mostly to setup the right calls and
 -- an initial state.
 
 -- Run a given TransformSession. Used mostly to setup the right calls and
 -- an initial state.