X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=2b5c8999147c03662ff5bf806cab27af9e992ff3;hb=74c1f82bd035a57c9df445d803644fb338b32120;hp=8b35bb986bd4265df2ec58e6988fc21f04fe64de;hpb=9a431787ceb299b15106b0dfd07701913cf2b515;p=matthijs%2Fmaster-project%2Fc%CE%BBash.git diff --git "a/c\316\273ash/CLasH/Normalize.hs" "b/c\316\273ash/CLasH/Normalize.hs" index 8b35bb9..2b5c899 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -4,39 +4,37 @@ -- top level function "normalize", and defines the actual transformation passes that -- are performed. -- -module CLasH.Normalize (getNormalized, normalizeExpr) where +module CLasH.Normalize (getNormalized, normalizeExpr, splitNormalized) where -- Standard modules import Debug.Trace import qualified Maybe +import qualified List import qualified "transformers" Control.Monad.Trans as Trans import qualified Control.Monad as Monad import qualified Control.Monad.Trans.Writer as Writer -import qualified Data.Map as Map +import qualified Data.Accessor.Monad.Trans.State as MonadState import qualified Data.Monoid as Monoid -import Data.Accessor +import qualified Data.Map as Map -- GHC API import CoreSyn -import qualified UniqSupply import qualified CoreUtils import qualified Type -import qualified TcType import qualified Id import qualified Var +import qualified Name import qualified VarSet -import qualified NameSet import qualified CoreFVs -import qualified CoreUtils +import qualified Class import qualified MkCore -import qualified HscTypes import Outputable ( showSDoc, ppr, nest ) -- Local imports import CLasH.Normalize.NormalizeTypes import CLasH.Translator.TranslatorTypes import CLasH.Normalize.NormalizeTools -import CLasH.VHDL.VHDLTypes +import CLasH.VHDL.Constants (builtinIds) import qualified CLasH.Utils as Utils import CLasH.Utils.Core.CoreTools import CLasH.Utils.Core.BinderTools @@ -47,32 +45,40 @@ import CLasH.Utils.Pretty -------------------------------- -------------------------------- --- η abstraction +-- η expansion -------------------------------- +-- Make sure all parameters to the normalized functions are named by top +-- level lambda expressions. For this we apply η expansion to the +-- function body (possibly enclosed in some lambda abstractions) while +-- it has a function type. Eventually this will result in a function +-- body consisting of a bunch of nested lambdas containing a +-- non-function value (e.g., a complete application). eta, etatop :: Transform -eta expr | is_fun expr && not (is_lam expr) = do +eta c expr | is_fun expr && not (is_lam expr) && all (== LambdaBody) c = do let arg_ty = (fst . Type.splitFunTy . CoreUtils.exprType) expr id <- Trans.lift $ mkInternalVar "param" arg_ty change (Lam id (App expr (Var id))) -- Leave all other expressions unchanged -eta e = return e -etatop = notappargs ("eta", eta) +eta c e = return e +etatop = everywhere ("eta", eta) -------------------------------- -- β-reduction -------------------------------- beta, betatop :: Transform --- Substitute arg for x in expr -beta (App (Lam x expr) arg) = change $ substitute [(x, arg)] expr +-- Substitute arg for x in expr. For value lambda's, also clone before +-- substitution. +beta c (App (Lam x expr) arg) | CoreSyn.isTyVar x = setChanged >> substitute x arg c expr + | otherwise = setChanged >> substitute_clone x arg c expr -- Propagate the application into the let -beta (App (Let binds expr) arg) = change $ Let binds (App expr arg) +beta c (App (Let binds expr) arg) = change $ Let binds (App expr arg) -- Propagate the application into each of the alternatives -beta (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts' +beta c (App (Case scrut b ty alts) arg) = change $ Case scrut b ty' alts' where alts' = map (\(con, bndrs, expr) -> (con, bndrs, (App expr arg))) alts ty' = CoreUtils.applyTypeToArg ty arg -- Leave all other expressions unchanged -beta expr = return expr +beta c expr = return expr -- Perform this transform everywhere betatop = everywhere ("beta", beta) @@ -81,60 +87,113 @@ betatop = everywhere ("beta", beta) -------------------------------- -- Try to move casts as much downward as possible. castprop, castproptop :: Transform -castprop (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty) -castprop expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts') +castprop c (Cast (Let binds expr) ty) = change $ Let binds (Cast expr ty) +castprop c expr@(Cast (Case scrut b _ alts) ty) = change (Case scrut b ty alts') where alts' = map (\(con, bndrs, expr) -> (con, bndrs, (Cast expr ty))) alts -- Leave all other expressions unchanged -castprop expr = return expr +castprop c expr = return expr -- Perform this transform everywhere castproptop = everywhere ("castprop", castprop) -------------------------------- --- let recursification +-- Cast simplification. Mostly useful for state packing and unpacking, but +-- perhaps for others as well. -------------------------------- -letrec, letrectop :: Transform -letrec (Let (NonRec b expr) res) = change $ Let (Rec [(b, expr)]) res +castsimpl, castsimpltop :: Transform +castsimpl c expr@(Cast val ty) = do + -- Don't extract values that are already simpl + local_var <- Trans.lift $ is_local_var val + -- Don't extract values that are not representable, to prevent loops with + -- inlinenonrep + repr <- isRepr val + if (not local_var) && repr + then do + -- Generate a binder for the expression + id <- Trans.lift $ mkBinderFor val "castval" + -- Extract the expression + change $ Let (NonRec id val) (Cast (Var id) ty) + else + return expr -- Leave all other expressions unchanged -letrec expr = return expr +castsimpl c expr = return expr -- Perform this transform everywhere -letrectop = everywhere ("letrec", letrec) +castsimpltop = everywhere ("castsimpl", castsimpl) -------------------------------- --- let simplification +-- Ensure that a function that just returns another function (or rather, +-- another top-level binder) is still properly normalized. This is a temporary +-- solution, we should probably integrate this pass with lambdasimpl and +-- letsimpl instead. -------------------------------- -letsimpl, letsimpltop :: Transform --- Put the "in ..." value of a let in its own binding, but not when the --- expression is already a local variable, or not representable (to prevent loops with inlinenonrep). -letsimpl expr@(Let (Rec binds) res) = do - repr <- isRepr res - local_var <- Trans.lift $ is_local_var res +retvalsimpl c expr@(Let (Rec binds) body) | all (== LambdaBody) c = do + -- Don't extract values that are already a local variable, to prevent + -- loops with ourselves. + local_var <- Trans.lift $ is_local_var body + -- Don't extract values that are not representable, to prevent loops with + -- inlinenonrep + repr <- isRepr body if not local_var && repr then do - -- If the result is not a local var already (to prevent loops with - -- ourselves), extract it. - id <- Trans.lift $ mkInternalVar "foo" (CoreUtils.exprType res) - let bind = (id, res) - change $ Let (Rec (bind:binds)) (Var id) + id <- Trans.lift $ mkBinderFor body "res" + change $ Let (Rec ((id, body):binds)) (Var id) else - -- If the result is already a local var, don't extract it. return expr +retvalsimpl c expr | all (== LambdaBody) c && not (is_lam expr) && not (is_let expr) = do + local_var <- Trans.lift $ is_local_var expr + repr <- isRepr expr + if not local_var && repr + then do + id <- Trans.lift $ mkBinderFor expr "res" + change $ Let (Rec [(id, expr)]) (Var id) + else + return expr + +-- Leave all other expressions unchanged +retvalsimpl c expr = return expr +-- Perform this transform everywhere +retvalsimpltop = everywhere ("retvalsimpl", retvalsimpl) + +-------------------------------- +-- let derecursification +-------------------------------- +letderec, letderectop :: Transform +letderec c expr@(Let (Rec binds) res) = case liftable of + -- Nothing is liftable, just return + [] -> return expr + -- Something can be lifted, generate a new let expression + _ -> change $ mkNonRecLets liftable (Let (Rec nonliftable) res) + where + -- Make a list of all the binders bound in this recursive let + bndrs = map fst binds + -- See which bindings are liftable + (liftable, nonliftable) = List.partition canlift binds + -- Any expression that does not use any of the binders in this recursive let + -- can be lifted into a nonrec let. It can't use its own binder either, + -- since that would mean the binding is self-recursive and should be in a + -- single bind recursive let. + canlift (bndr, e) = not $ expr_uses_binders bndrs e -- Leave all other expressions unchanged -letsimpl expr = return expr +letderec c expr = return expr -- Perform this transform everywhere -letsimpltop = everywhere ("letsimpl", letsimpl) +letderectop = everywhere ("letderec", letderec) -------------------------------- -- let flattening -------------------------------- +-- Takes a let that binds another let, and turns that into two nested lets. +-- e.g., from: +-- let b = (let b' = expr' in res') in res +-- to: +-- let b' = expr' in (let b = res' in res) letflat, letflattop :: Transform -letflat (Let (Rec binds) expr) = do - -- Turn each binding into a list of bindings (possibly containing just one - -- element, of course) - bindss <- Monad.mapM flatbind binds - -- Concat all the bindings - let binds' = concat bindss +-- Turn a nonrec let that binds a let into two nested lets. +letflat c (Let (NonRec b (Let binds res')) res) = + change $ Let binds (Let (NonRec b res') res) +letflat c (Let (Rec binds) expr) = do + -- Flatten each binding. + binds' <- Utils.concatM $ Monad.mapM flatbind binds -- Return the new let. We don't use change here, since possibly nothing has -- changed. If anything has changed, flatbind has already flagged that -- change. @@ -144,60 +203,316 @@ letflat (Let (Rec binds) expr) = do -- into a list with just that binding flatbind :: (CoreBndr, CoreExpr) -> TransformMonad [(CoreBndr, CoreExpr)] flatbind (b, Let (Rec binds) expr) = change ((b, expr):binds) + flatbind (b, Let (NonRec b' expr') expr) = change [(b, expr), (b', expr')] flatbind (b, expr) = return [(b, expr)] -- Leave all other expressions unchanged -letflat expr = return expr +letflat c expr = return expr -- Perform this transform everywhere letflattop = everywhere ("letflat", letflat) +-------------------------------- +-- empty let removal +-------------------------------- +-- Remove empty (recursive) lets +letremove, letremovetop :: Transform +letremove c (Let (Rec []) res) = change res +-- Leave all other expressions unchanged +letremove c expr = return expr +-- Perform this transform everywhere +letremovetop = everywhere ("letremove", letremove) + -------------------------------- -- Simple let binding removal -------------------------------- -- Remove a = b bindings from let expressions everywhere -letremovetop :: Transform -letremovetop = everywhere ("letremove", inlinebind (\(b, e) -> Trans.lift $ is_local_var e)) +letremovesimpletop :: Transform +letremovesimpletop = everywhere ("letremovesimple", inlinebind (\(b, e) -> Trans.lift $ is_local_var e)) + +-------------------------------- +-- Unused let binding removal +-------------------------------- +letremoveunused, letremoveunusedtop :: Transform +letremoveunused c expr@(Let (NonRec b bound) res) = do + let used = expr_uses_binders [b] res + if used + then return expr + else change res +letremoveunused c expr@(Let (Rec binds) res) = do + -- Filter out all unused binds. + let binds' = filter dobind binds + -- Only set the changed flag if binds got removed + changeif (length binds' /= length binds) (Let (Rec binds') res) + where + bound_exprs = map snd binds + -- For each bind check if the bind is used by res or any of the bound + -- expressions + dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs) +-- Leave all other expressions unchanged +letremoveunused c expr = return expr +letremoveunusedtop = everywhere ("letremoveunused", letremoveunused) + +{- +-------------------------------- +-- Identical let binding merging +-------------------------------- +-- Merge two bindings in a let if they are identical +-- TODO: We would very much like to use GHC's CSE module for this, but that +-- doesn't track if something changed or not, so we can't use it properly. +letmerge, letmergetop :: Transform +letmerge c expr@(Let _ _) = do + let (binds, res) = flattenLets expr + binds' <- domerge binds + return $ mkNonRecLets binds' res + where + domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)] + domerge [] = return [] + domerge (e:es) = do + es' <- mapM (mergebinds e) es + es'' <- domerge es' + return (e:es'') + + -- Uses the second bind to simplify the second bind, if applicable. + mergebinds :: (CoreBndr, CoreExpr) -> (CoreBndr, CoreExpr) -> TransformMonad (CoreBndr, CoreExpr) + mergebinds (b1, e1) (b2, e2) + -- Identical expressions? Replace the second binding with a reference to + -- the first binder. + | CoreUtils.cheapEqExpr e1 e2 = change $ (b2, Var b1) + -- Different expressions? Don't change + | otherwise = return (b2, e2) +-- Leave all other expressions unchanged +letmerge c expr = return expr +letmergetop = everywhere ("letmerge", letmerge) +-} -------------------------------- --- Function inlining +-- Non-representable binding inlining -------------------------------- --- Remove a = B bindings, with B :: a -> b, or B :: forall x . T, from let --- expressions everywhere. This means that any value that still needs to be --- applied to something else (polymorphic values need to be applied to a --- Type) will be inlined, and will eventually be applied to all their --- arguments. +-- Remove a = B bindings, with B of a non-representable type, from let +-- expressions everywhere. This means that any value that we can't generate a +-- signal for, will be inlined and hopefully turned into something we can +-- represent. -- -- This is a tricky function, which is prone to create loops in the -- transformations. To fix this, we make sure that no transformation will --- create a new let binding with a function type. These other transformations --- will just not work on those function-typed values at first, but the other --- transformations (in particular β-reduction) should make sure that the type --- of those values eventually becomes primitive. +-- create a new let binding with a non-representable type. These other +-- transformations will just not work on those function-typed values at first, +-- but the other transformations (in particular β-reduction) should make sure +-- that the type of those values eventually becomes representable. inlinenonreptop :: Transform inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd)) +-------------------------------- +-- Top level function inlining +-------------------------------- +-- This transformation inlines simple top level bindings. Simple +-- currently means that the body is only a single application (though +-- the complexity of the arguments is not currently checked) or that the +-- normalized form only contains a single binding. This should catch most of the +-- cases where a top level function is created that simply calls a type class +-- method with a type and dictionary argument, e.g. +-- fromInteger = GHC.Num.fromInteger (SizedWord D8) $dNum +-- which is later called using simply +-- fromInteger (smallInteger 10) +-- +-- These useless wrappers are created by GHC automatically. If we don't +-- inline them, we get loads of useless components cluttering the +-- generated VHDL. +-- +-- Note that the inlining could also inline simple functions defined by +-- the user, not just GHC generated functions. It turns out to be near +-- impossible to reliably determine what functions are generated and +-- what functions are user-defined. Instead of guessing (which will +-- inline less than we want) we will just inline all simple functions. +-- +-- Only functions that are actually completely applied and bound by a +-- variable in a let expression are inlined. These are the expressions +-- that will eventually generate instantiations of trivial components. +-- By not inlining any other reference, we also prevent looping problems +-- with funextract and inlinedict. +inlinetoplevel, inlinetopleveltop :: Transform +inlinetoplevel (LetBinding:_) expr | not (is_fun expr) = + case collectArgs expr of + (Var f, args) -> do + body_maybe <- needsInline f + case body_maybe of + Just body -> do + -- Regenerate all uniques in the to-be-inlined expression + body_uniqued <- Trans.lift $ genUniques body + -- And replace the variable reference with the unique'd body. + change (mkApps body_uniqued args) + -- No need to inline + Nothing -> return expr + -- This is not an application of a binder, leave it unchanged. + _ -> return expr + +-- Leave all other expressions unchanged +inlinetoplevel c expr = return expr +inlinetopleveltop = everywhere ("inlinetoplevel", inlinetoplevel) + +-- | Does the given binder need to be inlined? If so, return the body to +-- be used for inlining. +needsInline :: CoreBndr -> TransformMonad (Maybe CoreExpr) +needsInline f = do + body_maybe <- Trans.lift $ getGlobalBind f + case body_maybe of + -- No body available? + Nothing -> return Nothing + Just body -> case CoreSyn.collectArgs body of + -- The body is some (top level) binder applied to 0 or more + -- arguments. That should be simple enough to inline. + (Var f, args) -> return $ Just body + -- Body is more complicated, try normalizing it + _ -> do + norm_maybe <- Trans.lift $ getNormalized_maybe f + case norm_maybe of + -- Noth normalizeable + Nothing -> return Nothing + Just norm -> case splitNormalized norm of + -- The function has just a single binding, so that's simple + -- enough to inline. + (args, [bind], res) -> return $ Just norm + -- More complicated function, don't inline + _ -> return Nothing + +-------------------------------- +-- Dictionary inlining +-------------------------------- +-- Inline all top level dictionaries, that are in a position where +-- classopresolution can actually resolve them. This makes this +-- transformation look similar to classoperesolution below, but we'll +-- keep them separated for clarity. By not inlining other dictionaries, +-- we prevent expression sizes exploding when huge type level integer +-- dictionaries are inlined which can never be expanded (in casts, for +-- example). +inlinedict c expr@(App (App (Var sel) ty) (Var dict)) | not is_builtin && is_classop = do + body_maybe <- Trans.lift $ getGlobalBind dict + case body_maybe of + -- No body available (no source available, or a local variable / + -- argument) + Nothing -> return expr + Just body -> change (App (App (Var sel) ty) body) + where + -- Is this a builtin function / method? + is_builtin = elem (Name.getOccString sel) builtinIds + -- Are we dealing with a class operation selector? + is_classop = Maybe.isJust (Id.isClassOpId_maybe sel) + +-- Leave all other expressions unchanged +inlinedict c expr = return expr +inlinedicttop = everywhere ("inlinedict", inlinedict) + +-------------------------------- +-- ClassOp resolution +-------------------------------- +-- Resolves any class operation to the actual operation whenever +-- possible. Class methods (as well as parent dictionary selectors) are +-- special "functions" that take a type and a dictionary and evaluate to +-- the corresponding method. A dictionary is nothing more than a +-- special dataconstructor applied to the type the dictionary is for, +-- each of the superclasses and all of the class method definitions for +-- that particular type. Since dictionaries all always inlined (top +-- levels dictionaries are inlined by inlinedict, local dictionaries are +-- inlined by inlinenonrep), we will eventually have something like: +-- +-- baz +-- @ CLasH.HardwareTypes.Bit +-- (D:Baz @ CLasH.HardwareTypes.Bit bitbaz) +-- +-- Here, baz is the method selector for the baz method, while +-- D:Baz is the dictionary constructor for the Baz and bitbaz is the baz +-- method defined in the Baz Bit instance declaration. +-- +-- To resolve this, we can look at the ClassOp IdInfo from the baz Id, +-- which contains the Class it is defined for. From the Class, we can +-- get a list of all selectors (both parent class selectors as well as +-- method selectors). Since the arguments to D:Baz (after the type +-- argument) correspond exactly to this list, we then look up baz in +-- that list and replace the entire expression by the corresponding +-- argument to D:Baz. +-- +-- We don't resolve methods that have a builtin translation (such as +-- ==), since the actual implementation is not always (easily) +-- translateable. For example, when deriving ==, GHC generates code +-- using $con2tag functions to translate a datacon to an int and compare +-- that with GHC.Prim.==# . Better to avoid that for now. +classopresolution, classopresolutiontop :: Transform +classopresolution c expr@(App (App (Var sel) ty) dict) | not is_builtin = + case Id.isClassOpId_maybe sel of + -- Not a class op selector + Nothing -> return expr + Just cls -> case collectArgs dict of + (_, []) -> return expr -- Dict is not an application (e.g., not inlined yet) + (Var dictdc, (ty':selectors)) | not (Maybe.isJust (Id.isDataConId_maybe dictdc)) -> return expr -- Dictionary is not a datacon yet (but e.g., a top level binder) + | tyargs_neq ty ty' -> error $ "Normalize.classopresolution: Applying class selector to dictionary without matching type?\n" ++ pprString expr + | otherwise -> + let selector_ids = Class.classSelIds cls in + -- Find the selector used in the class' list of selectors + case List.elemIndex sel selector_ids of + Nothing -> error $ "Normalize.classopresolution: Selector not found in class' selector list? This should not happen!\nExpression: " ++ pprString expr ++ "\nClass: " ++ show cls ++ "\nSelectors: " ++ show selector_ids + -- Get the corresponding argument from the dictionary + Just n -> change (selectors!!n) + (_, _) -> return expr -- Not applying a variable? Don't touch + where + -- Compare two type arguments, returning True if they are _not_ + -- equal + tyargs_neq (Type ty1) (Type ty2) = not $ Type.coreEqType ty1 ty2 + tyargs_neq _ _ = True + -- Is this a builtin function / method? + is_builtin = elem (Name.getOccString sel) builtinIds + +-- Leave all other expressions unchanged +classopresolution c expr = return expr +-- Perform this transform everywhere +classopresolutiontop = everywhere ("classopresolution", classopresolution) + -------------------------------- -- Scrutinee simplification -------------------------------- scrutsimpl,scrutsimpltop :: Transform -- Don't touch scrutinees that are already simple -scrutsimpl expr@(Case (Var _) _ _ _) = return expr +scrutsimpl c expr@(Case (Var _) _ _ _) = return expr -- Replace all other cases with a let that binds the scrutinee and a new -- simple scrutinee, but only when the scrutinee is representable (to prevent -- loops with inlinenonrep, though I don't think a non-representable scrutinee -- will be supported anyway...) -scrutsimpl expr@(Case scrut b ty alts) = do +scrutsimpl c expr@(Case scrut b ty alts) = do repr <- isRepr scrut if repr then do - id <- Trans.lift $ mkInternalVar "scrut" (CoreUtils.exprType scrut) - change $ Let (Rec [(id, scrut)]) (Case (Var id) b ty alts) + id <- Trans.lift $ mkBinderFor scrut "scrut" + change $ Let (NonRec id scrut) (Case (Var id) b ty alts) else return expr -- Leave all other expressions unchanged -scrutsimpl expr = return expr +scrutsimpl c expr = return expr -- Perform this transform everywhere scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl) +-------------------------------- +-- Scrutinee binder removal +-------------------------------- +-- A case expression can have an extra binder, to which the scrutinee is bound +-- after bringing it to WHNF. This is used for forcing evaluation of strict +-- arguments. Since strictness does not matter for us (rather, everything is +-- sort of strict), this binder is ignored when generating VHDL, and must thus +-- be wild in the normal form. +scrutbndrremove, scrutbndrremovetop :: Transform +-- If the scrutinee is already simple, and the bndr is not wild yet, replace +-- all occurences of the binder with the scrutinee variable. +scrutbndrremove c (Case (Var scrut) bndr ty alts) | bndr_used = do + alts' <- mapM subs_bndr alts + change $ Case (Var scrut) wild ty alts' + where + is_used (_, _, expr) = expr_uses_binders [bndr] expr + bndr_used = or $ map is_used alts + subs_bndr (con, bndrs, expr) = do + expr' <- substitute bndr (Var scrut) c expr + return (con, bndrs, expr') + wild = MkCore.mkWildBinder (Id.idType bndr) +-- Leave all other expressions unchanged +scrutbndrremove c expr = return expr +scrutbndrremovetop = everywhere ("scrutbndrremove", scrutbndrremove) + -------------------------------- -- Case binder wildening -------------------------------- @@ -205,24 +520,27 @@ casesimpl, casesimpltop :: Transform -- This is already a selector case (or, if x does not appear in bndrs, a very -- simple case statement that will be removed by caseremove below). Just leave -- it be. -casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr +casesimpl c expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr -- Make sure that all case alternatives have only wild binders and simple -- expressions. -- This is done by creating a new let binding for each non-wild binder, which -- is bound to a new simple selector case statement and for each complex -- expression. We do this only for representable types, to prevent loops with -- inlinenonrep. -casesimpl expr@(Case scrut b ty alts) = do +casesimpl c expr@(Case scrut bndr ty alts) | not bndr_used = do (bindingss, alts') <- (Monad.liftM unzip) $ mapM doalt alts let bindings = concat bindingss -- Replace the case with a let with bindings and a case - let newlet = (Let (Rec bindings) (Case scrut b ty alts')) + let newlet = mkNonRecLets bindings (Case scrut bndr ty alts') -- If there are no non-wild binders, or this case is already a simple -- selector (i.e., a single alt with exactly one binding), already a simple -- selector altan no bindings (i.e., no wild binders in the original case), -- don't change anything, otherwise, replace the case. if null bindings then return expr else change newlet where + -- Check if the scrutinee binder is used + is_used (_, _, expr) = expr_uses_binders [bndr] expr + bndr_used = or $ map is_used alts -- Generate a single wild binder, since they are all the same wild = MkCore.mkWildBinder -- Wilden the binders of one alt, producing a list of bindings as a @@ -235,11 +553,11 @@ casesimpl expr@(Case scrut b ty alts) = do -- Extract a complex expression, if possible. For this we check if any of -- the new list of bndrs are used by expr. We can't use free_vars here, -- since that looks at the old bndrs. - let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) $ expr + let uses_bndrs = not $ VarSet.isEmptyVarSet $ CoreFVs.exprSomeFreeVars (`elem` newbndrs) expr (exprbinding_maybe, expr') <- doexpr expr uses_bndrs -- Create a new alternative let newalt = (con, newbndrs, expr') - let bindings = Maybe.catMaybes (exprbinding_maybe : bindings_maybe) + let bindings = Maybe.catMaybes (bindings_maybe ++ [exprbinding_maybe]) return (bindings, newalt) where -- Make wild alternatives for each binder @@ -251,7 +569,7 @@ casesimpl expr@(Case scrut b ty alts) = do -- binding containing a case expression. dobndr :: CoreBndr -> Int -> TransformMonad (CoreBndr, Maybe (CoreBndr, CoreExpr)) dobndr b i = do - repr <- isRepr (Var b) + repr <- isRepr b -- Is b wild (e.g., not a free var of expr. Since b is only in scope -- in expr, this means that b is unused if expr does not use it.) let wild = not (VarSet.elemVarSet b free_vars) @@ -283,15 +601,15 @@ casesimpl expr@(Case scrut b ty alts) = do -- prevent loops with inlinenonrep). if (not uses_bndrs) && (not local_var) && repr then do - id <- Trans.lift $ mkInternalVar "caseval" (CoreUtils.exprType expr) + id <- Trans.lift $ mkBinderFor expr "caseval" -- We don't flag a change here, since casevalsimpl will do that above -- based on Just we return here. - return $ (Just (id, expr), Var id) + return (Just (id, expr), Var id) else -- Don't simplify anything else return (Nothing, expr) -- Leave all other expressions unchanged -casesimpl expr = return expr +casesimpl c expr = return expr -- Perform this transform everywhere casesimpltop = everywhere ("casesimpl", casesimpl) @@ -302,11 +620,11 @@ casesimpltop = everywhere ("casesimpl", casesimpl) -- binders. caseremove, caseremovetop :: Transform -- Replace a useless case by the value of its single alternative -caseremove (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr +caseremove c (Case scrut b ty [(con, bndrs, expr)]) | not usesvars = change expr -- Find if any of the binders are used by expr - where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` bndrs))) expr + where usesvars = (not . VarSet.isEmptyVarSet . (CoreFVs.exprSomeFreeVars (`elem` b:bndrs))) expr -- Leave all other expressions unchanged -caseremove expr = return expr +caseremove c expr = return expr -- Perform this transform everywhere caseremovetop = everywhere ("caseremove", caseremove) @@ -317,18 +635,18 @@ caseremovetop = everywhere ("caseremove", caseremove) appsimpl, appsimpltop :: Transform -- Simplify all representable arguments. Do this by introducing a new Let -- that binds the argument and passing the new binder in the application. -appsimpl expr@(App f arg) = do +appsimpl c expr@(App f arg) = do -- Check runtime representability repr <- isRepr arg local_var <- Trans.lift $ is_local_var arg if repr && not local_var then do -- Extract representable arguments - id <- Trans.lift $ mkInternalVar "arg" (CoreUtils.exprType arg) - change $ Let (Rec [(id, arg)]) (App f (Var id)) + id <- Trans.lift $ mkBinderFor arg "arg" + change $ Let (NonRec id arg) (App f (Var id)) else -- Leave non-representable arguments unchanged return expr -- Leave all other expressions unchanged -appsimpl expr = return expr +appsimpl c expr = return expr -- Perform this transform everywhere appsimpltop = everywhere ("appsimpl", appsimpl) @@ -342,7 +660,7 @@ argprop, argproptop :: Transform -- Transform any application of a named function (i.e., skip applications of -- lambda's). Also skip applications that have arguments with free type -- variables, since we can't inline those. -argprop expr@(App _ _) | is_var fexpr = do +argprop c expr@(App _ _) | is_var fexpr = do -- Find the body of the function called body_maybe <- Trans.lift $ getGlobalBind f case body_maybe of @@ -360,6 +678,12 @@ argprop expr@(App _ _) | is_var fexpr = do let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs) -- Create a new function with the same name but a new body newf <- Trans.lift $ mkFunction f newbody + + Trans.lift $ MonadState.modify tsInitStates (\ismap -> + let init_state_maybe = Map.lookup f ismap in + case init_state_maybe of + Nothing -> ismap + Just init_state -> Map.insert newf init_state ismap) -- Replace the original application with one of the new function to the -- new arguments. change $ MkCore.mkCoreApps (Var newf) newargs @@ -384,7 +708,7 @@ argprop expr@(App _ _) | is_var fexpr = do doarg arg = do repr <- isRepr arg bndrs <- Trans.lift getGlobalBinders - let interesting var = Var.isLocalVar var && (not $ var `elem` bndrs) + let interesting var = Var.isLocalVar var && (var `notElem` bndrs) if not repr && not (is_var arg && interesting (exprToVar arg)) && not (has_free_tyvars arg) then do -- Propagate all complex arguments that are not representable, but not @@ -400,17 +724,25 @@ argprop expr@(App _ _) | is_var fexpr = do let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting arg -- Mark the current expression as changed setChanged + -- TODO: Clone the free_vars (and update references in arg), since + -- this might cause conflicts if two arguments that are propagated + -- share a free variable. Also, we are now introducing new variables + -- into a function that are not fresh, which violates the binder + -- uniqueness invariant. return (map Var free_vars, free_vars, arg) else do -- Representable types will not be propagated, and arguments with free -- type variables will be propagated later. + -- Note that we implicitly remove any type variables in the type of + -- the original argument by using the type of the actual argument + -- for the new formal parameter. -- TODO: preserve original naming? id <- Trans.lift $ mkBinderFor arg "param" -- Just pass the original argument to the new function, which binds it -- to a new id and just pass that new id to the old function body. return ([arg], [id], mkReferenceTo id) -- Leave all other expressions unchanged -argprop expr = return expr +argprop c expr = return expr -- Perform this transform everywhere argproptop = everywhere ("argprop", argprop) @@ -423,7 +755,7 @@ argproptop = everywhere ("argprop", argprop) -- apply map to a lambda expression This will not conflict with inlinenonrep, -- since that only inlines local let bindings, not top level bindings. funextract, funextracttop :: Transform -funextract expr@(App _ _) | is_var fexpr = do +funextract c expr@(App _ _) | is_var fexpr = do body_maybe <- Trans.lift $ getGlobalBind f case body_maybe of -- We don't have a function body for f, so we can perform this transform. @@ -461,7 +793,7 @@ funextract expr@(App _ _) | is_var fexpr = do doarg arg = return arg -- Leave all other expressions unchanged -funextract expr = return expr +funextract c expr = return expr -- Perform this transform everywhere funextracttop = everywhere ("funextract", funextract) @@ -473,22 +805,43 @@ funextracttop = everywhere ("funextract", funextract) -- What transforms to run? -transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop] +transforms = [inlinedicttop, inlinetopleveltop, classopresolutiontop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letderectop, letremovetop, retvalsimpltop, letflattop, scrutsimpltop, scrutbndrremovetop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop] --- | Returns the normalized version of the given function. +-- | Returns the normalized version of the given function, or an error +-- if it is not a known global binder. getNormalized :: CoreBndr -- ^ The function to get -> TranslatorSession CoreExpr -- The normalized function body - -getNormalized bndr = Utils.makeCached bndr tsNormalized $ do - if is_poly (Var bndr) - then - -- This should really only happen at the top level... TODO: Give - -- a different error if this happens down in the recursion. - error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize" - else do - expr <- getBinding bndr - normalizeExpr (show bndr) expr +getNormalized bndr = do + norm <- getNormalized_maybe bndr + return $ Maybe.fromMaybe + (error $ "Normalize.getNormalized: Unknown or non-representable function requested: " ++ show bndr) + norm + +-- | Returns the normalized version of the given function, or Nothing +-- when the binder is not a known global binder or is not normalizeable. +getNormalized_maybe :: + CoreBndr -- ^ The function to get + -> TranslatorSession (Maybe CoreExpr) -- The normalized function body + +getNormalized_maybe bndr = do + expr_maybe <- getGlobalBind bndr + normalizeable <- isNormalizeable' bndr + if not normalizeable || Maybe.isNothing expr_maybe + then + -- Binder not normalizeable or not found + return Nothing + else if is_poly (Var bndr) + then + -- This should really only happen at the top level... TODO: Give + -- a different error if this happens down in the recursion. + error $ "\nNormalize.normalizeBind: Function " ++ show bndr ++ " is polymorphic, can't normalize" + else do + -- Binder found and is monomorphic. Normalize the expression + -- and cache the result. + normalized <- Utils.makeCached bndr tsNormalized $ + normalizeExpr (show bndr) (Maybe.fromJust expr_maybe) + return (Just normalized) -- | Normalize an expression normalizeExpr :: @@ -497,23 +850,25 @@ normalizeExpr :: -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression normalizeExpr what expr = do - -- Introduce an empty Let at the top level, so there will always be - -- a let in the expression (none of the transformations will remove - -- the last let). - let expr' = Let (Rec []) expr + startcount <- MonadState.get tsTransformCounter + expr_uniqued <- genUniques expr -- Normalize this expression - trace ("Transforming " ++ what ++ "\nBefore:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return () - expr'' <- dotransforms transforms expr' - trace ("\nAfter:\n\n" ++ showSDoc ( ppr expr')) $ return () - return expr'' - --- | Get the value that is bound to the given binder at top level. Fails when --- there is no such binding. -getBinding :: - CoreBndr -- ^ The binder to get the expression for - -> TranslatorSession CoreExpr -- ^ The value bound to the binder - -getBinding bndr = Utils.makeCached bndr tsBindings $ do - -- If the binding isn't in the "cache" (bindings map), then we can't create - -- it out of thin air, so return an error. - error $ "Normalize.getBinding: Unknown function requested: " ++ show bndr + trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr_uniqued ) ++ "\n") $ return () + expr' <- dotransforms transforms expr_uniqued + endcount <- MonadState.get tsTransformCounter + trace ("\n" ++ what ++ " after normalization:\n\n" ++ showSDoc ( ppr expr')) $ return () + trace ("\nNeeded " ++ show (endcount - startcount) ++ " transformations to normalize " ++ what) $ return () + return expr' + +-- | Split a normalized expression into the argument binders, top level +-- bindings and the result binder. +splitNormalized :: + CoreExpr -- ^ The normalized expression + -> ([CoreBndr], [Binding], CoreBndr) +splitNormalized expr = (args, binds, res) + where + (args, letexpr) = CoreSyn.collectBinders expr + (binds, resexpr) = flattenLets letexpr + res = case resexpr of + (Var x) -> x + _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n"