From 82b40598ea7a9c00abdeae37bc47896f880fbbdc Mon Sep 17 00:00:00 2001 From: Simon Peyton Jones Date: Tue, 14 Mar 2017 13:52:48 +0000 Subject: Fix CaseIdentity optimisation AGAIN In this commit commit 02ac2974ce8e537372bff8d9e0a6efb461ed2c59 Author: Simon Peyton Jones Date: Wed Nov 16 10:37:47 2011 +0000 Fix CaseIdentity optimisaion In fixing one bug I'd introduced another; case x of { T -> T; F -> F } wasn't getting optmised! Trivial to fix. I introduced yet another! This line of code in SimplUtils.mkCase1 check_eq (Var v) (DataAlt con) [] = v == dataConWorkId con -- Optimisation only is patently false when arg_tys is non-empty. Astonishing that it has not shown up before now. Easily fixed though. This was all shown up by Trac #13417, which is now fixed. Merge to 8.0, 8.2. --- compiler/simplCore/SimplUtils.hs | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'compiler/simplCore') diff --git a/compiler/simplCore/SimplUtils.hs b/compiler/simplCore/SimplUtils.hs index 0fe262b2c7..49bb6c4991 100644 --- a/compiler/simplCore/SimplUtils.hs +++ b/compiler/simplCore/SimplUtils.hs @@ -1886,21 +1886,21 @@ mkCase1 _dflags scrut case_bndr _ alts@((_,_,rhs1) : _) -- Identity case ticks = concatMap (stripTicksT tickishFloatable . thdOf3) (tail alts) identity_alt (con, args, rhs) = check_eq rhs con args - check_eq (Cast rhs co) con args + check_eq (Cast rhs co) con args -- See Note [RHS casts] = not (any (`elemVarSet` tyCoVarsOfCo co) args) && check_eq rhs con args - -- See Note [RHS casts] - check_eq (Lit lit) (LitAlt lit') _ = lit == lit' + check_eq (Tick t e) alt args + = tickishFloatable t && check_eq e alt args + + check_eq (Lit lit) (LitAlt lit') _ = lit == lit' check_eq (Var v) _ _ | v == case_bndr = True - check_eq (Var v) (DataAlt con) [] = v == dataConWorkId con + check_eq (Var v) (DataAlt con) args + | null arg_tys, null args = v == dataConWorkId con -- Optimisation only - check_eq (Tick t e) alt args = tickishFloatable t && - check_eq e alt args check_eq rhs (DataAlt con) args = cheapEqExpr' tickishFloatable rhs $ - mkConApp con (arg_tys ++ - varsToCoreExprs args) + mkConApp2 con arg_tys args check_eq _ _ _ = False - arg_tys = map Type (tyConAppArgs (idType case_bndr)) + arg_tys = tyConAppArgs (idType case_bndr) -- Note [RHS casts] -- ~~~~~~~~~~~~~~~~ -- cgit v1.2.1