X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=dc3c0c2052141045c09b53f6af5af42012a50d6d;hb=c29a9d04d534beedb2221a03f672310af16dd0cd;hp=f3a9d2e4662ca2e204d761fa1c80fc4272628a73;hpb=cc6bc95b0549cecd2aa13a5ee17f3fba3af5a1c1;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 f3a9d2e..dc3c0c2 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -4,39 +4,40 @@ -- 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 BasicTypes import qualified Type -import qualified TcType +import qualified TysWiredIn import qualified Id import qualified Var +import qualified Name +import qualified DataCon 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 @@ -47,55 +48,98 @@ import CLasH.Utils.Pretty -------------------------------- -------------------------------- --- η abstraction +-- η expansion -------------------------------- -eta, etatop :: Transform -eta expr | is_fun expr && not (is_lam expr) = do +-- 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 :: Transform +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 -------------------------------- -- β-reduction -------------------------------- -beta, betatop :: Transform --- Substitute arg for x in expr -beta (App (Lam x expr) arg) = change $ substitute [(x, arg)] expr +beta :: Transform +-- 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 --- Perform this transform everywhere -betatop = everywhere ("beta", beta) +beta c expr = return expr + +-------------------------------- +-- Case of known constructor simplification +-------------------------------- +-- If a case expressions scrutinizes a datacon application, we can +-- determine which alternative to use and remove the case alltogether. +-- We replace it with a let expression the binds every binder in the +-- alternative bound to the corresponding argument of the datacon. We do +-- this instead of substituting the binders, to prevent duplication of +-- work and preserve sharing wherever appropriate. +knowncase :: Transform +knowncase context expr@(Case scrut@(App _ _) bndr ty alts) | not bndr_used = do + case collectArgs scrut of + (Var f, args) -> case Id.isDataConId_maybe f of + -- Not a dataconstructor? Don't change anything (probably a + -- function, then) + Nothing -> return expr + Just dc -> do + let (altcon, bndrs, res) = case List.find (\(altcon, bndrs, res) -> altcon == (DataAlt dc)) alts of + Just alt -> alt -- Return the alternative found + Nothing -> head alts -- If the datacon is not present, the first must be the default alternative + -- Double check if we have either the correct alternative, or + -- the default. + if altcon /= (DataAlt dc) && altcon /= DEFAULT then error ("Normalize.knowncase: Invalid core, datacon not found in alternatives and DEFAULT alternative is not first? " ++ pprString expr) else return () + -- Find out how many arguments to drop (type variables and + -- predicates like dictionaries). + let (tvs, preds, _, _) = DataCon.dataConSig dc + let count = length tvs + length preds + -- Create a let expression that binds each of the binders in + -- this alternative to the corresponding argument of the data + -- constructor. + let binds = zip bndrs (drop count args) + change $ Let (Rec binds) res + _ -> return expr -- Scrutinee is not an application of a var + where + is_used (_, _, expr) = expr_uses_binders [bndr] expr + bndr_used = or $ map is_used alts + +-- Leave all other expressions unchanged +knowncase c expr = return expr -------------------------------- -- Cast propagation -------------------------------- -- 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 :: Transform +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 --- Perform this transform everywhere -castproptop = everywhere ("castprop", castprop) +castprop c expr = return expr -------------------------------- -- Cast simplification. Mostly useful for state packing and unpacking, but -- perhaps for others as well. -------------------------------- -castsimpl, castsimpltop :: Transform -castsimpl expr@(Cast val ty) = do +castsimpl :: 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 @@ -106,59 +150,73 @@ castsimpl expr@(Cast val ty) = do -- Generate a binder for the expression id <- Trans.lift $ mkBinderFor val "castval" -- Extract the expression - change $ Let (Rec [(id, val)]) (Cast (Var id) ty) + change $ Let (NonRec id val) (Cast (Var id) ty) else return expr -- Leave all other expressions unchanged -castsimpl expr = return expr --- Perform this transform everywhere -castsimpltop = everywhere ("castsimpl", castsimpl) +castsimpl c expr = return expr -------------------------------- --- let recursification +-- Return value simplification -------------------------------- -letrec, letrectop :: Transform -letrec (Let (NonRec b expr) res) = change $ Let (Rec [(b, expr)]) res --- Leave all other expressions unchanged -letrec expr = return expr --- Perform this transform everywhere -letrectop = everywhere ("letrec", letrec) +-- Ensure the return value of a function follows proper normal form. eta +-- expansion ensures the body starts with lambda abstractions, this +-- transformation ensures that the lambda abstractions always contain a +-- recursive let and that, when the return value is representable, the +-- let contains a local variable reference in its body. +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 --------------------------------- --- let simplification --------------------------------- -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 $ mkBinderFor res "foo" - 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 + -- Leave all other expressions unchanged -letsimpl expr = return expr --- Perform this transform everywhere -letsimpltop = everywhere ("letsimpl", letsimpl) +retvalsimpl c expr = return expr + +-------------------------------- +-- let derecursification +-------------------------------- +letrec :: Transform +letrec c expr@(Let (NonRec bndr val) res) = + change $ Let (Rec [(bndr, val)]) res + +-- Leave all other expressions unchanged +letrec c expr = return expr -------------------------------- -- let flattening -------------------------------- -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 +-- 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 :: Transform +-- 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. @@ -168,24 +226,37 @@ 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 --- Perform this transform everywhere -letflattop = everywhere ("letflat", letflat) +letflat c expr = return expr + +-------------------------------- +-- empty let removal +-------------------------------- +-- Remove empty (recursive) lets +letremove :: Transform +letremove c (Let (Rec []) res) = change res +-- Leave all other expressions unchanged +letremove c expr = return expr -------------------------------- -- 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)) +letremovesimple :: Transform +letremovesimple = inlinebind (\(b, e) -> Trans.lift $ is_local_var e) -------------------------------- -- Unused let binding removal -------------------------------- -letremoveunused, letremoveunusedtop :: Transform -letremoveunused expr@(Let (Rec binds) res) = do +letremoveunused :: 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 @@ -196,19 +267,20 @@ letremoveunused expr@(Let (Rec binds) res) = do -- expressions dobind (bndr, _) = any (expr_uses_binders [bndr]) (res:bound_exprs) -- Leave all other expressions unchanged -letremoveunused expr = return expr -letremoveunusedtop = everywhere ("letremoveunused", letremoveunused) +letremoveunused c expr = return expr +{- -------------------------------- -- 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 expr@(Let (Rec binds) res) = do +letmerge :: Transform +letmerge c expr@(Let _ _) = do + let (binds, res) = flattenLets expr binds' <- domerge binds - return (Let (Rec binds') res) + return $ mkNonRecLets binds' res where domerge :: [(CoreBndr, CoreExpr)] -> TransformMonad [(CoreBndr, CoreExpr)] domerge [] = return [] @@ -226,75 +298,259 @@ letmerge expr@(Let (Rec binds) res) = do -- Different expressions? Don't change | otherwise = return (b2, e2) -- Leave all other expressions unchanged -letmerge expr = return expr -letmergetop = everywhere ("letmerge", letmerge) - +letmerge c expr = return expr +-} + -------------------------------- --- 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. -inlinenonreptop :: Transform -inlinenonreptop = everywhere ("inlinenonrep", inlinebind ((Monad.liftM not) . isRepr . snd)) +-- 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. +inlinenonrep :: Transform +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 :: 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 + +-- | 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 False f + case norm_maybe of + -- Noth normalizeable + Nothing -> return Nothing + Just norm -> case splitNormalizedNonRep norm of + -- The function has just a single binding, so that's simple + -- enough to inline. + (args, [bind], Var 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 + +-------------------------------- +-- 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 :: 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 -------------------------------- -- Scrutinee simplification -------------------------------- -scrutsimpl,scrutsimpltop :: Transform +scrutsimpl :: 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 $ mkBinderFor scrut "scrut" - change $ Let (Rec [(id, scrut)]) (Case (Var id) b ty alts) + change $ Let (NonRec id scrut) (Case (Var id) b ty alts) else return expr -- Leave all other expressions unchanged -scrutsimpl expr = return expr --- Perform this transform everywhere -scrutsimpltop = everywhere ("scrutsimpl", scrutsimpl) +scrutsimpl c expr = return expr + +-------------------------------- +-- 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 :: 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 -------------------------------- -- Case binder wildening -------------------------------- -casesimpl, casesimpltop :: Transform +casesimpl :: 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 @@ -307,11 +563,11 @@ 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 @@ -323,7 +579,7 @@ 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) @@ -332,12 +588,9 @@ casesimpl expr@(Case scrut b ty alts) = do -- inlinenonrep). if (not wild) && repr then do - -- Create on new binder that will actually capture a value in this + caseexpr <- Trans.lift $ mkSelCase scrut i + -- Create a new binder that will actually capture a value in this -- case statement, and return it. - let bty = (Id.idType b) - id <- Trans.lift $ mkInternalVar "sel" bty - let binders = take i wildbndrs ++ [id] ++ drop (i+1) wildbndrs - let caseexpr = Case scrut b bty [(con, binders, Var id)] return (wildbndrs!!i, Just (b, caseexpr)) else -- Just leave the original binder in place, and don't generate an @@ -358,51 +611,45 @@ casesimpl expr@(Case scrut b ty alts) = do 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 --- Perform this transform everywhere -casesimpltop = everywhere ("casesimpl", casesimpl) +casesimpl c expr = return expr -------------------------------- -- Case removal -------------------------------- -- Remove case statements that have only a single alternative and only wild -- binders. -caseremove, caseremovetop :: Transform +caseremove :: 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 --- Perform this transform everywhere -caseremovetop = everywhere ("caseremove", caseremove) +caseremove c expr = return expr -------------------------------- -- Argument extraction -------------------------------- -- Make sure that all arguments of a representable type are simple variables. -appsimpl, appsimpltop :: Transform +appsimpl :: 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 $ mkBinderFor arg "arg" - change $ Let (Rec [(id, arg)]) (App f (Var id)) + 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 --- Perform this transform everywhere -appsimpltop = everywhere ("appsimpl", appsimpl) +appsimpl c expr = return expr -------------------------------- -- Function-typed argument propagation @@ -410,11 +657,11 @@ appsimpltop = everywhere ("appsimpl", appsimpl) -- Remove all applications to function-typed arguments, by duplication the -- function called with the function-typed parameter replaced by the free -- variables of the argument passed in. -argprop, argproptop :: Transform +argprop :: 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 @@ -432,6 +679,12 @@ 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 @@ -456,7 +709,7 @@ 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 @@ -472,19 +725,124 @@ 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 --- Perform this transform everywhere -argproptop = everywhere ("argprop", argprop) +argprop c expr = return expr + +-------------------------------- +-- Non-representable result inlining +-------------------------------- +-- This transformation takes a function (top level binding) that has a +-- non-representable result (e.g., a tuple containing a function, or an +-- Integer. The latter can occur in some cases as the result of the +-- fromIntegerT function) and inlines enough of the function to make the +-- result representable again. +-- +-- This is done by first normalizing the function and then "inlining" +-- the result. Since no unrepresentable let bindings are allowed in +-- normal form, we can be sure that all free variables of the result +-- expression will be representable (Note that we probably can't +-- guarantee that all representable parts of the expression will be free +-- variables, so we might inline more than strictly needed). +-- +-- The new function result will be a tuple containing all free variables +-- of the old result, so the old result can be rebuild at the caller. +-- +-- We take care not to inline dictionary id's, which are top level +-- bindings with a non-representable result type as well, since those +-- will never become VHDL signals directly. There is a separate +-- transformation (inlinedict) that specifically inlines dictionaries +-- only when it is useful. +inlinenonrepresult :: Transform + +-- Apply to any (application of) a reference to a top level function +-- that is fully applied (i.e., dos not have a function type) but is not +-- representable. We apply in any context, since non-representable +-- expressions are generally left alone and can occur anywhere. +inlinenonrepresult context expr | not (is_fun expr) = + case collectArgs expr of + (Var f, args) | not (Id.isDictId f) -> do + repr <- isRepr expr + if not repr + then do + body_maybe <- Trans.lift $ getNormalized_maybe True f + case body_maybe of + Just body -> do + let (bndrs, binds, res) = splitNormalizedNonRep body + if has_free_tyvars res + then + -- Don't touch anything with free type variables, since + -- we can't return those. We'll wait until argprop + -- removed those variables. + return expr + else do + -- Get the free local variables of res + global_bndrs <- Trans.lift getGlobalBinders + let interesting var = Var.isLocalVar var && (var `notElem` global_bndrs) + let free_vars = VarSet.varSetElems $ CoreFVs.exprSomeFreeVars interesting res + let free_var_types = map Id.idType free_vars + let n_free_vars = length free_vars + -- Get a tuple datacon to wrap around the free variables + let fvs_datacon = TysWiredIn.tupleCon BasicTypes.Boxed n_free_vars + let fvs_datacon_id = DataCon.dataConWorkId fvs_datacon + -- Let the function now return a tuple with references to + -- all free variables of the old return value. First pass + -- all the types of the variables, since tuple + -- constructors are polymorphic. + let newres = mkApps (Var fvs_datacon_id) (map Type free_var_types ++ map Var free_vars) + -- Recreate the function body with the changed return value + let newbody = mkLams bndrs (Let (Rec binds) newres) + -- Create the new function + f' <- Trans.lift $ mkFunction f newbody + + -- Call the new function + let newapp = mkApps (Var f') args + res_bndr <- Trans.lift $ mkBinderFor newapp "res" + -- Create extractor case expressions to extract each of the + -- free variables from the tuple. + sel_cases <- Trans.lift $ mapM (mkSelCase (Var res_bndr)) [0..n_free_vars-1] + + -- Bind the res_bndr to the result of the new application + -- and each of the free variables to the corresponding + -- selector case. Replace the let body with the original + -- body of the called function (which can still access all + -- of its free variables, from the let). + let binds = (res_bndr, newapp):(zip free_vars sel_cases) + let letexpr = Let (Rec binds) res + + -- Finally, regenarate all uniques in the new expression, + -- since the free variables could otherwise become + -- duplicated. It is not strictly necessary to regenerate + -- res, since we're moving that expression, but it won't + -- hurt. + letexpr_uniqued <- Trans.lift $ genUniques letexpr + change letexpr_uniqued + Nothing -> return expr + else + -- Don't touch representable expressions or (applications of) + -- dictionary ids. + return expr + -- Not a reference to or application of a top level function + _ -> return expr +-- Leave all other expressions unchanged +inlinenonrepresult c expr = return expr + -------------------------------- -- Function-typed argument extraction @@ -494,8 +852,8 @@ argproptop = everywhere ("argprop", argprop) -- puts it in a brand new top level binder. This allows us to for example -- 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 :: Transform +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. @@ -533,9 +891,7 @@ funextract expr@(App _ _) | is_var fexpr = do doarg arg = return arg -- Leave all other expressions unchanged -funextract expr = return expr --- Perform this transform everywhere -funextracttop = everywhere ("funextract", funextract) +funextract c expr = return expr -------------------------------- -- End of transformations @@ -545,22 +901,63 @@ funextracttop = everywhere ("funextract", funextract) -- What transforms to run? -transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop] - --- | Returns the normalized version of the given function. +transforms = [ ("inlinedict", inlinedict) + , ("inlinetoplevel", inlinetoplevel) + , ("inlinenonrepresult", inlinenonrepresult) + , ("knowncase", knowncase) + , ("classopresolution", classopresolution) + , ("argprop", argprop) + , ("funextract", funextract) + , ("eta", eta) + , ("beta", beta) + , ("castprop", castprop) + , ("letremovesimple", letremovesimple) + , ("letrec", letrec) + , ("letremove", letremove) + , ("retvalsimpl", retvalsimpl) + , ("letflat", letflat) + , ("scrutsimpl", scrutsimpl) + , ("scrutbndrremove", scrutbndrremove) + , ("casesimpl", casesimpl) + , ("caseremove", caseremove) + , ("inlinenonrep", inlinenonrep) + , ("appsimpl", appsimpl) + , ("letremoveunused", letremoveunused) + , ("castsimpl", castsimpl) + ] + +-- | 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 + Bool -- ^ Allow the result to be unrepresentable? + -> 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 result_nonrep bndr = do + norm <- getNormalized_maybe result_nonrep 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 :: + Bool -- ^ Allow the result to be unrepresentable? + -> CoreBndr -- ^ The function to get + -> TranslatorSession (Maybe CoreExpr) -- The normalized function body + +getNormalized_maybe result_nonrep bndr = do + expr_maybe <- getGlobalBind bndr + normalizeable <- isNormalizeable result_nonrep bndr + if not normalizeable || Maybe.isNothing expr_maybe + then + -- Binder not normalizeable or not found + return Nothing + 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 :: @@ -569,23 +966,32 @@ 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') + ++ "\nNeeded " ++ show (endcount - startcount) ++ " transformations to normalize " ++ what) $ + return expr' + +-- | Split a normalized expression into the argument binders, top level +-- bindings and the result binder. This function returns an error if +-- the type of the expression is not representable. +splitNormalized :: + CoreExpr -- ^ The normalized expression + -> ([CoreBndr], [Binding], CoreBndr) +splitNormalized expr = + case splitNormalizedNonRep expr of + (args, binds, Var res) -> (args, binds, res) + _ -> error $ "Normalize.splitNormalized: Not in normal form: " ++ pprString expr ++ "\n" + +-- Split a normalized expression, whose type can be unrepresentable. +splitNormalizedNonRep:: + CoreExpr -- ^ The normalized expression + -> ([CoreBndr], [Binding], CoreExpr) +splitNormalizedNonRep expr = (args, binds, resexpr) + where + (args, letexpr) = CoreSyn.collectBinders expr + (binds, resexpr) = flattenLets letexpr