+
+-- | Generate new uniques for all binders in the given expression.
+-- Does not support making type variables unique, though this could be
+-- supported if required (by passing a CoreSubst.Subst instead of VarEnv to
+-- genUniques' below).
+genUniques :: CoreSyn.CoreExpr -> TranslatorSession CoreSyn.CoreExpr
+genUniques = genUniques' VarEnv.emptyVarEnv
+
+-- | A helper function to generate uniques, that takes a VarEnv containing the
+-- substitutions already performed.
+genUniques' :: VarEnv.VarEnv CoreSyn.CoreBndr -> CoreSyn.CoreExpr -> TranslatorSession CoreSyn.CoreExpr
+genUniques' subst (CoreSyn.Var f) = do
+ -- Replace the binder with its new value, if applicable.
+ let f' = VarEnv.lookupWithDefaultVarEnv subst f f
+ return (CoreSyn.Var f')
+-- Leave literals untouched
+genUniques' subst (CoreSyn.Lit l) = return $ CoreSyn.Lit l
+genUniques' subst (CoreSyn.App f arg) = do
+ -- Only work on subexpressions
+ f' <- genUniques' subst f
+ arg' <- genUniques' subst arg
+ return (CoreSyn.App f' arg')
+-- Don't change type abstractions
+genUniques' subst expr@(CoreSyn.Lam bndr res) | CoreSyn.isTyVar bndr = return expr
+genUniques' subst (CoreSyn.Lam bndr res) = do
+ -- Generate a new unique for the bound variable
+ (subst', bndr') <- genUnique subst bndr
+ res' <- genUniques' subst' res
+ return (CoreSyn.Lam bndr' res')
+genUniques' subst (CoreSyn.Let (CoreSyn.NonRec bndr bound) res) = do
+ -- Make the binders unique
+ (subst', bndr') <- genUnique subst bndr
+ bound' <- genUniques' subst' bound
+ res' <- genUniques' subst' res
+ return $ CoreSyn.Let (CoreSyn.NonRec bndr' bound') res'
+genUniques' subst (CoreSyn.Let (CoreSyn.Rec binds) res) = do
+ -- Make each of the binders unique
+ (subst', bndrs') <- mapAccumLM genUnique subst (map fst binds)
+ bounds' <- mapM (genUniques' subst' . snd) binds
+ res' <- genUniques' subst' res
+ let binds' = zip bndrs' bounds'
+ return $ CoreSyn.Let (CoreSyn.Rec binds') res'
+genUniques' subst (CoreSyn.Case scrut bndr ty alts) = do
+ -- Process the scrutinee with the original substitution, since non of the
+ -- binders bound in the Case statement is in scope in the scrutinee.
+ scrut' <- genUniques' subst scrut
+ -- Generate a new binder for the scrutinee
+ (subst', bndr') <- genUnique subst bndr
+ -- Process each of the alts
+ alts' <- mapM (doalt subst') alts
+ return $ CoreSyn.Case scrut' bndr' ty alts'
+ where
+ doalt subst (con, bndrs, expr) = do
+ (subst', bndrs') <- mapAccumLM genUnique subst bndrs
+ expr' <- genUniques' subst' expr
+ -- Note that we don't return subst', since bndrs are only in scope in
+ -- expr.
+ return (con, bndrs', expr')
+genUniques' subst (CoreSyn.Cast expr coercion) = do
+ expr' <- genUniques' subst expr
+ -- Just process the casted expression
+ return $ CoreSyn.Cast expr' coercion
+genUniques' subst (CoreSyn.Note note expr) = do
+ expr' <- genUniques' subst expr
+ -- Just process the annotated expression
+ return $ CoreSyn.Note note expr'
+-- Leave types untouched
+genUniques' subst expr@(CoreSyn.Type _) = return expr
+
+-- Generate a new unique for the given binder, and extend the given
+-- substitution to reflect this.
+genUnique :: VarEnv.VarEnv CoreSyn.CoreBndr -> CoreSyn.CoreBndr -> TranslatorSession (VarEnv.VarEnv CoreSyn.CoreBndr, CoreSyn.CoreBndr)
+genUnique subst bndr = do
+ bndr' <- BinderTools.cloneVar bndr
+ -- Replace all occurences of the old binder with a reference to the new
+ -- binder.
+ let subst' = VarEnv.extendVarEnv subst bndr bndr'
+ return (subst', bndr')
+
+-- Create a "selector" case that selects the ith field from a datacon
+mkSelCase :: CoreSyn.CoreExpr -> Int -> TranslatorSession CoreSyn.CoreExpr
+mkSelCase scrut i = do
+ let scrut_ty = CoreUtils.exprType scrut
+ case Type.splitTyConApp_maybe scrut_ty of
+ -- The scrutinee should have a type constructor. We keep the type
+ -- arguments around so we can instantiate the field types below
+ Just (tycon, tyargs) -> case TyCon.tyConDataCons tycon of
+ -- The scrutinee type should have a single dataconstructor,
+ -- otherwise we can't construct a valid selector case.
+ [datacon] -> do
+ let field_tys = DataCon.dataConInstOrigArgTys datacon tyargs
+ -- Create a list of wild binders for the fields we don't want
+ let wildbndrs = map MkCore.mkWildBinder field_tys
+ -- Create a single binder for the field we want
+ sel_bndr <- mkInternalVar "sel" (field_tys!!i)
+ -- Create a wild binder for the scrutinee
+ let scrut_bndr = MkCore.mkWildBinder scrut_ty
+ -- Create the case expression
+ let binders = take i wildbndrs ++ [sel_bndr] ++ drop (i+1) wildbndrs
+ return $ CoreSyn.Case scrut scrut_bndr scrut_ty [(CoreSyn.DataAlt datacon, binders, CoreSyn.Var sel_bndr)]
+ dcs -> error $ "CoreTools.mkSelCase: Scrutinee type must have exactly one datacon. Extracting element " ++ (show i) ++ " from '" ++ pprString scrut ++ "' Datacons: " ++ (show dcs) ++ " Type: " ++ (pprString scrut_ty)
+ Nothing -> error $ "CoreTools.mkSelCase: Creating extractor case, but scrutinee has no tycon? Extracting element " ++ (show i) ++ " from '" ++ pprString scrut ++ "'" ++ " Type: " ++ (pprString scrut_ty)
projects / matthijs / master-project / cλash.git / blobdiff