X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=c%CE%BBash%2FCLasH%2FNormalize.hs;h=9f754709dd3699a04d6009b74cc45b0581ccc87b;hb=151af68f4ae2fc9d156282775b06aa332debcf08;hp=8e6926aa7c4d4ac59b3f159e690a1bee58ffb634;hpb=0ebe9a48cf38f84ea2a365f776c854947fd90a30;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 8e6926a..9f75470 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -24,6 +24,7 @@ import qualified Type import qualified Id import qualified Var import qualified Name +import qualified DataCon import qualified VarSet import qualified CoreFVs import qualified Class @@ -82,6 +83,48 @@ beta c expr = return expr -- Perform this transform everywhere betatop = everywhere ("beta", beta) +-------------------------------- +-- 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, knowncasetop :: 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 +-- Perform this transform everywhere +knowncasetop = everywhere ("knowncase", knowncase) + -------------------------------- -- Cast propagation -------------------------------- @@ -354,14 +397,14 @@ needsInline f = do (Var f, args) -> return $ Just body -- Body is more complicated, try normalizing it _ -> do - norm_maybe <- Trans.lift $ getNormalized_maybe f + norm_maybe <- Trans.lift $ getNormalized_maybe False f case norm_maybe of -- Noth normalizeable Nothing -> return Nothing - Just norm -> case splitNormalized norm of + Just norm -> case splitNormalizedNonRep norm of -- The function has just a single binding, so that's simple -- enough to inline. - (args, [bind], res) -> return $ Just norm + (args, [bind], Var res) -> return $ Just norm -- More complicated function, don't inline _ -> return Nothing @@ -569,12 +612,9 @@ casesimpl c expr@(Case scrut bndr ty alts) | not bndr_used = 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 @@ -796,15 +836,16 @@ funextracttop = everywhere ("funextract", funextract) -- What transforms to run? -transforms = [inlinedicttop, inlinetopleveltop, classopresolutiontop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letrectop, letremovetop, retvalsimpltop, letflattop, scrutsimpltop, scrutbndrremovetop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop] +transforms = [inlinedicttop, inlinetopleveltop, knowncasetop, classopresolutiontop, argproptop, funextracttop, etatop, betatop, castproptop, letremovesimpletop, letrectop, letremovetop, retvalsimpltop, letflattop, scrutsimpltop, scrutbndrremovetop, casesimpltop, caseremovetop, inlinenonreptop, appsimpltop, letremoveunusedtop, castsimpltop] -- | 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 = do - norm <- getNormalized_maybe bndr +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 @@ -812,27 +853,23 @@ getNormalized bndr = do -- | 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 + Bool -- ^ Allow the result to be unrepresentable? + -> CoreBndr -- ^ The function to get -> TranslatorSession (Maybe CoreExpr) -- The normalized function body -getNormalized_maybe bndr = do +getNormalized_maybe result_nonrep bndr = do expr_maybe <- getGlobalBind bndr - normalizeable <- isNormalizeable' bndr + normalizeable <- isNormalizeable result_nonrep 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) + 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 ::