X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=6a4825d42406343c5b6eb94191fdaf5b4ed554e0;hb=7d60f355a116d10adef0a66370d8bfa6a859e8b2;hp=8ec195b0ef936aadd89449571988da9e3c4f56e0;hpb=1f94e5a3010ebce788762ab08ce022d3f7d8f033;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 8ec195b..6a4825d 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -4,11 +4,12 @@ -- top level function "normalize", and defines the actual transformation passes that -- are performed. -- -module CLasH.Normalize (normalizeModule) 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 @@ -34,9 +35,12 @@ import Outputable ( showSDoc, ppr, nest ) -- Local imports import CLasH.Normalize.NormalizeTypes +import CLasH.Translator.TranslatorTypes import CLasH.Normalize.NormalizeTools import CLasH.VHDL.VHDLTypes +import qualified CLasH.Utils as Utils import CLasH.Utils.Core.CoreTools +import CLasH.Utils.Core.BinderTools import CLasH.Utils.Pretty -------------------------------- @@ -49,7 +53,7 @@ import CLasH.Utils.Pretty eta, etatop :: Transform eta expr | is_fun expr && not (is_lam expr) = do let arg_ty = (fst . Type.splitFunTy . CoreUtils.exprType) expr - id <- mkInternalVar "param" arg_ty + id <- Trans.lift $ mkInternalVar "param" arg_ty change (Lam id (App expr (Var id))) -- Leave all other expressions unchanged eta e = return e @@ -88,31 +92,74 @@ castprop expr = return expr castproptop = everywhere ("castprop", castprop) -------------------------------- --- let recursification +-- Cast simplification. Mostly useful for state packing and unpacking, but +-- perhaps for others as well. +-------------------------------- +castsimpl, castsimpltop :: Transform +castsimpl 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 +castsimpl expr = return expr +-- Perform this transform everywhere +castsimpltop = everywhere ("castsimpl", castsimpl) + -------------------------------- -letrec, letrectop :: Transform -letrec (Let (NonRec b expr) res) = change $ Let (Rec [(b, expr)]) res +-- let derecursification +-------------------------------- +letderec, letderectop :: Transform +letderec 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 $ MkCore.mkCoreLets newbinds 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 + -- Create nonrec bindings for each liftable binding and a single recursive + -- binding for all others + newbinds = (map (uncurry NonRec) liftable) ++ [Rec nonliftable] + -- 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 -letrec expr = return expr +letderec expr = return expr -- Perform this transform everywhere -letrectop = everywhere ("letrec", letrec) +letderectop = everywhere ("letderec", letderec) -------------------------------- -- let simplification -------------------------------- letsimpl, letsimpltop :: Transform +-- Don't simplify a let that evaluates to another let, since this is already +-- normal form (and would cause infinite loops with letflat below). +letsimpl expr@(Let _ (Let _ _)) = return expr -- 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 +letsimpl expr@(Let binds res) = do repr <- isRepr res local_var <- Trans.lift $ is_local_var res if not local_var && repr then do -- If the result is not a local var already (to prevent loops with -- ourselves), extract it. - id <- mkInternalVar "foo" (CoreUtils.exprType res) - let bind = (id, res) - change $ Let (Rec (bind:binds)) (Var id) + id <- Trans.lift $ mkBinderFor res "foo" + change $ Let binds (Let (NonRec id res) (Var id)) else -- If the result is already a local var, don't extract it. return expr @@ -125,23 +172,14 @@ letsimpltop = everywhere ("letsimpl", letsimpl) -------------------------------- -- 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 - -- 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. - return $ Let (Rec binds') expr - where - -- Turns a binding of a let into a multiple bindings, or any other binding - -- 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, expr) = return [(b, expr)] +letflat (Let (NonRec b (Let (NonRec b' expr') res')) res) = + change $ Let (NonRec b' expr') (Let (NonRec b res') res) -- Leave all other expressions unchanged letflat expr = return expr -- Perform this transform everywhere @@ -154,6 +192,54 @@ letflattop = everywhere ("letflat", letflat) letremovetop :: Transform letremovetop = everywhere ("letremove", inlinebind (\(b, e) -> Trans.lift $ is_local_var e)) +-------------------------------- +-- Unused let binding removal +-------------------------------- +letremoveunused, letremoveunusedtop :: Transform +letremoveunused 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 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 expr@(Let (Rec binds) res) = do + binds' <- domerge binds + return (Let (Rec 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 expr = return expr +letmergetop = everywhere ("letmerge", letmerge) + -------------------------------- -- Function inlining -------------------------------- @@ -186,8 +272,8 @@ scrutsimpl expr@(Case scrut b ty alts) = do repr <- isRepr scrut if repr then do - id <- 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 @@ -260,7 +346,7 @@ casesimpl expr@(Case scrut b ty alts) = do -- Create on new binder that will actually capture a value in this -- case statement, and return it. let bty = (Id.idType b) - id <- mkInternalVar "sel" bty + 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)) @@ -280,7 +366,7 @@ casesimpl expr@(Case scrut b ty alts) = do -- prevent loops with inlinenonrep). if (not uses_bndrs) && (not local_var) && repr then do - id <- 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) @@ -320,8 +406,8 @@ appsimpl expr@(App f arg) = do local_var <- Trans.lift $ is_local_var arg if repr && not local_var then do -- Extract representable arguments - id <- 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 @@ -356,7 +442,7 @@ argprop expr@(App _ _) | is_var fexpr = do -- the old body applied to some arguments. let newbody = MkCore.mkCoreLams newparams (MkCore.mkCoreApps body oldargs) -- Create a new function with the same name but a new body - newf <- mkFunction f newbody + newf <- Trans.lift $ mkFunction f newbody -- Replace the original application with one of the new function to the -- new arguments. change $ MkCore.mkCoreApps (Var newf) newargs @@ -402,7 +488,7 @@ argprop expr@(App _ _) | is_var fexpr = do -- Representable types will not be propagated, and arguments with free -- type variables will be propagated later. -- TODO: preserve original naming? - id <- mkBinderFor arg "param" + 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) @@ -449,7 +535,7 @@ funextract expr@(App _ _) | is_var fexpr = do -- by the argument expression. let free_vars = VarSet.varSetElems $ CoreFVs.exprFreeVars arg let body = MkCore.mkCoreLams free_vars arg - id <- mkBinderFor body "fun" + id <- Trans.lift $ mkBinderFor body "fun" Trans.lift $ addGlobalBind id body -- Replace the argument with a reference to the new function, applied to -- all vars it uses. @@ -470,80 +556,71 @@ funextracttop = everywhere ("funextract", funextract) -- What transforms to run? -transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letrectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop] - --- Turns the given bind into VHDL -normalizeModule :: - HscTypes.HscEnv - -> UniqSupply.UniqSupply -- ^ A UniqSupply we can use - -> [(CoreBndr, CoreExpr)] -- ^ All bindings we know (i.e., in the current module) - -> [CoreExpr] - -> [CoreBndr] -- ^ The bindings to generate VHDL for (i.e., the top level bindings) - -> [Bool] -- ^ For each of the bindings to generate VHDL for, if it is stateful - -> ([(CoreBndr, CoreExpr)], [(CoreBndr, CoreExpr)], TypeState) -- ^ The resulting VHDL - -normalizeModule env uniqsupply bindings testexprs generate_for statefuls = runTransformSession env uniqsupply $ do - testbinds <- mapM (\x -> do { v <- mkBinderFor' x "test" ; return (v,x) } ) testexprs - let testbinders = (map fst testbinds) - -- Put all the bindings in this module in the tsBindings map - putA tsBindings (Map.fromList (bindings ++ testbinds)) - -- (Recursively) normalize each of the requested bindings - mapM normalizeBind (generate_for ++ testbinders) - -- Get all initial bindings and the ones we produced - bindings_map <- getA tsBindings - let bindings = Map.assocs bindings_map - normalized_binders' <- getA tsNormalized - let normalized_binders = VarSet.delVarSetList normalized_binders' testbinders - let ret_testbinds = zip testbinders (Maybe.catMaybes $ map (\x -> lookup x bindings) testbinders) - let ret_binds = filter ((`VarSet.elemVarSet` normalized_binders) . fst) bindings - typestate <- getA tsType - -- But return only the normalized bindings - return $ (ret_binds, ret_testbinds, typestate) - -normalizeBind :: CoreBndr -> TransformSession () -normalizeBind bndr = - -- Don't normalize global variables, these should be either builtin - -- functions or data constructors. - Monad.when (Var.isLocalId bndr) $ do - -- Skip binders that have a polymorphic type, since it's impossible to - -- create polymorphic hardware. - 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 - normalized_funcs <- getA tsNormalized - -- See if this function was normalized already - if VarSet.elemVarSet bndr normalized_funcs - then - -- Yup, don't do it again - return () - else do - -- Nope, note that it has been and do it. - modA tsNormalized (flip VarSet.extendVarSet bndr) - expr_maybe <- getGlobalBind bndr - case expr_maybe of - Just 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 - -- Normalize this expression - trace ("Transforming " ++ (show bndr) ++ "\nBefore:\n\n" ++ showSDoc ( ppr expr' ) ++ "\n") $ return () - expr' <- dotransforms transforms expr' - trace ("\nAfter:\n\n" ++ showSDoc ( ppr expr')) $ return () - -- And store the normalized version in the session - modA tsBindings (Map.insert bndr expr') - -- Find all vars used with a function type. All of these should be global - -- binders (i.e., functions used), since any local binders with a function - -- type should have been inlined already. - bndrs <- getGlobalBinders - let used_funcs_set = CoreFVs.exprSomeFreeVars (\v -> not (Id.isDictId v) && v `elem` bndrs) expr' - let used_funcs = VarSet.varSetElems used_funcs_set - -- Process each of the used functions recursively - mapM normalizeBind used_funcs - return () - -- We don't have a value for this binder. This really shouldn't - -- happen for local id's... - Nothing -> error $ "\nNormalize.normalizeBind: No value found for binder " ++ pprString bndr ++ "? This should not happen!" +transforms = [argproptop, funextracttop, etatop, betatop, castproptop, letremovetop, letderectop, letsimpltop, letflattop, scrutsimpltop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letmergetop, letremoveunusedtop, castsimpltop] + +-- | Returns the normalized version of the given function. +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 + +-- | Normalize an expression +normalizeExpr :: + String -- ^ What are we normalizing? For debug output only. + -> CoreSyn.CoreExpr -- ^ The expression to normalize + -> TranslatorSession CoreSyn.CoreExpr -- ^ The normalized expression + +normalizeExpr what expr = do + -- Normalize this expression + trace (what ++ " before normalization:\n\n" ++ showSDoc ( ppr expr ) ++ "\n") $ return () + expr' <- dotransforms transforms expr + trace ("\n" ++ what ++ " after normalization:\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 + +-- | 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" + +-- | Flattens nested lets into a single list of bindings. The expression +-- passed does not have to be a let expression, if it isn't an empty list of +-- bindings is returned. +flattenLets :: + CoreExpr -- ^ The expression to flatten. + -> ([Binding], CoreExpr) -- ^ The bindings and resulting expression. +flattenLets (Let binds expr) = + (bindings ++ bindings', expr') + where + -- Recursively flatten the contained expression + (bindings', expr') =flattenLets expr + -- Flatten our own bindings to remove the Rec / NonRec constructors + bindings = CoreSyn.flattenBinds [binds] +flattenLets expr = ([], expr)