From: Matthijs Kooijman Date: Wed, 10 Mar 2010 13:54:04 +0000 (+0100) Subject: Fix casesimpl and caseremove wrt scrutinee binders. X-Git-Url: https://git.stderr.nl/gitweb?a=commitdiff_plain;h=392d75eeca669762072ed691573533b2a0bba664;p=matthijs%2Fmaster-project%2Fc%CE%BBash.git Fix casesimpl and caseremove wrt scrutinee binders. Previously, they would not check if the scrutinee binder was used, resulting in it being removed or incorrectly used in some cases. --- diff --git "a/c\316\273ash/CLasH/Normalize.hs" "b/c\316\273ash/CLasH/Normalize.hs" index 2f056d7..bbdd239 100644 --- "a/c\316\273ash/CLasH/Normalize.hs" +++ "b/c\316\273ash/CLasH/Normalize.hs" @@ -499,17 +499,20 @@ casesimpl expr@(Case scrut b ty [(con, bndrs, Var x)]) = return expr -- 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 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 = mkNonRecLets 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 @@ -591,7 +594,7 @@ 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 -- 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