X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fspecialise%2FRules.lhs;h=90485d0487a13ca0e8b8c7c8ede565071013ddbf;hp=d788b1b391c94f8892ad85ca6962ad7d87bc700b;hb=c86161c5cf11de77e911fcb9e1e2bd1f8bd80b42;hpb=ba7575afe6f7a6c9ae8417638ebecfe47c4c0c87 diff --git a/compiler/specialise/Rules.lhs b/compiler/specialise/Rules.lhs index d788b1b..90485d0 100644 --- a/compiler/specialise/Rules.lhs +++ b/compiler/specialise/Rules.lhs @@ -22,9 +22,9 @@ module Rules ( addIdSpecialisations, -- * Misc. CoreRule helpers - rulesOfBinds, getRules, pprRulesForUser, + rulesOfBinds, getRules, pprRulesForUser, - lookupRule, mkLocalRule, roughTopNames + lookupRule, mkRule, mkLocalRule, roughTopNames ) where #include "HsVersions.h" @@ -32,9 +32,9 @@ module Rules ( import CoreSyn -- All of it import OccurAnal ( occurAnalyseExpr ) import CoreFVs ( exprFreeVars, exprsFreeVars, bindFreeVars, rulesFreeVars ) -import CoreUtils ( tcEqExprX, exprType ) +import CoreUtils ( exprType ) import PprCore ( pprRules ) -import Type ( Type, TvSubstEnv ) +import Type ( Type, TvSubstEnv, tcEqTypeX ) import TcType ( tcSplitTyConApp_maybe ) import CoreTidy ( tidyRules ) import Id @@ -45,7 +45,7 @@ import VarSet import Name ( Name, NamedThing(..) ) import NameEnv import Unify ( ruleMatchTyX, MatchEnv(..) ) -import BasicTypes ( Activation ) +import BasicTypes ( Activation, CompilerPhase, isActive ) import StaticFlags ( opt_PprStyle_Debug ) import Outputable import FastString @@ -96,11 +96,18 @@ mkLocalRule :: RuleName -> Activation -> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule -- ^ Used to make 'CoreRule' for an 'Id' defined in the module being -- compiled. See also 'CoreSyn.CoreRule' -mkLocalRule name act fn bndrs args rhs +mkLocalRule = mkRule True + +mkRule :: Bool -> RuleName -> Activation + -> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule +-- ^ Used to make 'CoreRule' for an 'Id' defined in the module being +-- compiled. See also 'CoreSyn.CoreRule' +mkRule is_local name act fn bndrs args rhs = Rule { ru_name = name, ru_fn = fn, ru_act = act, ru_bndrs = bndrs, ru_args = args, - ru_rhs = rhs, ru_rough = roughTopNames args, - ru_local = True } + ru_rhs = occurAnalyseExpr rhs, + ru_rough = roughTopNames args, + ru_local = is_local } -------------- roughTopNames :: [CoreExpr] -> [Maybe Name] @@ -192,18 +199,32 @@ rulesOfBinds :: [CoreBind] -> [CoreRule] rulesOfBinds binds = concatMap (concatMap idCoreRules . bindersOf) binds getRules :: RuleBase -> Id -> [CoreRule] - -- The rules for an Id come from two places: - -- (a) the ones it is born with (idCoreRules fn) - -- (b) rules added in subsequent modules (extra_rules) - -- PrimOps, for example, are born with a bunch of rules under (a) +-- See Note [Where rules are found] getRules rule_base fn - | isLocalId fn = idCoreRules fn - | otherwise = WARN( not (isPrimOpId fn) && notNull (idCoreRules fn), - ppr fn <+> ppr (idCoreRules fn) ) - idCoreRules fn ++ (lookupNameEnv rule_base (idName fn) `orElse` []) - -- Only PrimOpIds have rules inside themselves, and perhaps more besides + = idCoreRules fn ++ imp_rules + where + imp_rules = lookupNameEnv rule_base (idName fn) `orElse` [] \end{code} +Note [Where rules are found] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The rules for an Id come from two places: + (a) the ones it is born with, stored inside the Id iself (idCoreRules fn), + (b) rules added in other modules, stored in the global RuleBase (imp_rules) + +It's tempting to think that + - LocalIds have only (a) + - non-LocalIds have only (b) + +but that isn't quite right: + + - PrimOps and ClassOps are born with a bunch of rules inside the Id, + even when they are imported + + - The rules in PrelRules.builtinRules should be active even + in the module defining the Id (when it's a LocalId), but + the rules are kept in the global RuleBase + %************************************************************************ %* * @@ -267,13 +288,15 @@ to lookupRule are the result of a lazy substitution -- supplied rules to this instance of an application in a given -- context, returning the rule applied and the resulting expression if -- successful. -lookupRule :: (Activation -> Bool) -> InScopeSet +lookupRule :: (Activation -> Bool) -- When rule is active + -> IdUnfoldingFun -- When Id can be unfolded + -> InScopeSet -> Id -> [CoreExpr] -> [CoreRule] -> Maybe (CoreRule, CoreExpr) -- See Note [Extra args in rule matching] -- See comments on matchRule -lookupRule is_active in_scope fn args rules +lookupRule is_active id_unf in_scope fn args rules = -- pprTrace "matchRules" (ppr fn <+> ppr rules) $ case go [] rules of [] -> Nothing @@ -283,7 +306,7 @@ lookupRule is_active in_scope fn args rules go :: [(CoreRule,CoreExpr)] -> [CoreRule] -> [(CoreRule,CoreExpr)] go ms [] = ms - go ms (r:rs) = case (matchRule is_active in_scope args rough_args r) of + go ms (r:rs) = case (matchRule is_active id_unf in_scope args rough_args r) of Just e -> go ((r,e):ms) rs Nothing -> -- pprTrace "match failed" (ppr r $$ ppr args $$ -- ppr [(arg_id, unfoldingTemplate unf) | Var arg_id <- args, let unf = idUnfolding arg_id, isCheapUnfolding unf] ) @@ -318,8 +341,9 @@ isMoreSpecific (BuiltinRule {}) _ = True isMoreSpecific _ (BuiltinRule {}) = False isMoreSpecific (Rule { ru_bndrs = bndrs1, ru_args = args1 }) (Rule { ru_bndrs = bndrs2, ru_args = args2 }) - = isJust (matchN in_scope bndrs2 args2 args1) + = isJust (matchN id_unfolding_fun in_scope bndrs2 args2 args1) where + id_unfolding_fun _ = NoUnfolding -- Don't expand in templates in_scope = mkInScopeSet (mkVarSet bndrs1) -- Actually we should probably include the free vars -- of rule1's args, but I can't be bothered @@ -327,7 +351,8 @@ isMoreSpecific (Rule { ru_bndrs = bndrs1, ru_args = args1 }) noBlackList :: Activation -> Bool noBlackList _ = False -- Nothing is black listed -matchRule :: (Activation -> Bool) -> InScopeSet +matchRule :: (Activation -> Bool) -> IdUnfoldingFun + -> InScopeSet -> [CoreExpr] -> [Maybe Name] -> CoreRule -> Maybe CoreExpr @@ -353,20 +378,21 @@ matchRule :: (Activation -> Bool) -> InScopeSet -- Any 'surplus' arguments in the input are simply put on the end -- of the output. -matchRule _is_active _in_scope args _rough_args +matchRule _is_active id_unf _in_scope args _rough_args (BuiltinRule { ru_try = match_fn }) - = case match_fn args of +-- Built-in rules can't be switched off, it seems + = case match_fn id_unf args of Just expr -> Just expr Nothing -> Nothing -matchRule is_active in_scope args rough_args +matchRule is_active id_unf in_scope args rough_args (Rule { ru_act = act, ru_rough = tpl_tops, ru_bndrs = tpl_vars, ru_args = tpl_args, ru_rhs = rhs }) | not (is_active act) = Nothing | ruleCantMatch tpl_tops rough_args = Nothing | otherwise - = case matchN in_scope tpl_vars tpl_args args of + = case matchN id_unf in_scope tpl_vars tpl_args args of Nothing -> Nothing Just (binds, tpl_vals) -> Just (mkLets binds $ rule_fn `mkApps` tpl_vals) @@ -379,14 +405,15 @@ matchRule is_active in_scope args rough_args -- For a given match template and context, find bindings to wrap around -- the entire result and what should be substituted for each template variable. -- Fail if there are two few actual arguments from the target to match the template -matchN :: InScopeSet -- ^ In-scope variables +matchN :: IdUnfoldingFun + -> InScopeSet -- ^ In-scope variables -> [Var] -- ^ Match template type variables -> [CoreExpr] -- ^ Match template -> [CoreExpr] -- ^ Target; can have more elements than the template -> Maybe ([CoreBind], [CoreExpr]) -matchN in_scope tmpl_vars tmpl_es target_es +matchN id_unf in_scope tmpl_vars tmpl_es target_es = do { (tv_subst, id_subst, binds) <- go init_menv emptySubstEnv tmpl_es target_es ; return (fromOL binds, @@ -399,7 +426,7 @@ matchN in_scope tmpl_vars tmpl_es target_es go _ subst [] _ = Just subst go _ _ _ [] = Nothing -- Fail if too few actual args - go menv subst (t:ts) (e:es) = do { subst1 <- match menv subst t e + go menv subst (t:ts) (e:es) = do { subst1 <- match id_unf menv subst t e ; go menv subst1 ts es } lookup_tmpl :: TvSubstEnv -> IdSubstEnv -> Var -> CoreExpr @@ -462,7 +489,8 @@ emptySubstEnv = (emptyVarEnv, emptyVarEnv, nilOL) -- SLPJ July 99 -match :: MatchEnv +match :: IdUnfoldingFun + -> MatchEnv -> SubstEnv -> CoreExpr -- Template -> CoreExpr -- Target @@ -484,118 +512,52 @@ match :: MatchEnv -- succeed in matching what looks like the template variable 'a' against 3. -- The Var case follows closely what happens in Unify.match -match menv subst (Var v1) e2 - | Just subst <- match_var menv subst v1 e2 +match idu menv subst (Var v1) e2 + | Just subst <- match_var idu menv subst v1 e2 = Just subst -match menv subst e1 (Note _ e2) - = match menv subst e1 e2 - -- Note [Notes in RULE matching] - -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -- Look through Notes. In particular, we don't want to - -- be confused by InlineMe notes. Maybe we should be more - -- careful about profiling notes, but for now I'm just - -- riding roughshod over them. - --- See Note [Notes in call patterns] in SpecConstr - --- Here is another important rule: if the term being matched is a --- variable, we expand it so long as its unfolding is a WHNF --- (Its occurrence information is not necessarily up to date, --- so we don't use it.) -match menv subst e1 (Var v2) - | isCheapUnfolding unfolding - = match menv subst e1 (unfoldingTemplate unfolding) +match idu menv subst (Note _ e1) e2 = match idu menv subst e1 e2 +match idu menv subst e1 (Note _ e2) = match idu menv subst e1 e2 + -- Ignore notes in both template and thing to be matched + -- See Note [Notes in RULE matching] + +match id_unfolding_fun menv subst e1 (Var v2) -- Note [Expanding variables] + | not (locallyBoundR rn_env v2) -- Note [Do not expand locally-bound variables] + , Just e2' <- expandUnfolding (id_unfolding_fun v2') + = match id_unfolding_fun (menv { me_env = nukeRnEnvR rn_env }) subst e1 e2' where - rn_env = me_env menv - unfolding = idUnfolding (lookupRnInScope rn_env (rnOccR rn_env v2)) + v2' = lookupRnInScope rn_env v2 + rn_env = me_env menv -- Notice that we look up v2 in the in-scope set -- See Note [Lookup in-scope] - -- Remember to apply any renaming first (hence rnOccR) - --- Note [Matching lets] --- ~~~~~~~~~~~~~~~~~~~~ --- Matching a let-expression. Consider --- RULE forall x. f (g x) = --- and target expression --- f (let { w=R } in g E)) --- Then we'd like the rule to match, to generate --- let { w=R } in (\x. ) E --- In effect, we want to float the let-binding outward, to enable --- the match to happen. This is the WHOLE REASON for accumulating --- bindings in the SubstEnv --- --- We can only do this if --- (a) Widening the scope of w does not capture any variables --- We use a conservative test: w is not already in scope --- If not, we clone the binders, and substitute --- (b) The free variables of R are not bound by the part of the --- target expression outside the let binding; e.g. --- f (\v. let w = v+1 in g E) --- Here we obviously cannot float the let-binding for w. --- --- You may think rule (a) would never apply, because rule matching is --- mostly invoked from the simplifier, when we have just run substExpr --- over the argument, so there will be no shadowing anyway. --- The fly in the ointment is that the forall'd variables of the --- RULE itself are considered in scope. --- --- I though of various cheapo ways to solve this tiresome problem, --- but ended up doing the straightforward thing, which is to --- clone the binders if they are in scope. It's tiresome, and --- potentially inefficient, because of the calls to substExpr, --- but I don't think it'll happen much in pracice. + -- No need to apply any renaming first (hence no rnOccR) + -- becuase of the not-locallyBoundR -{- Cases to think about - (let x=y+1 in \x. (x,x)) - --> let x=y+1 in (\x1. (x1,x1)) - (\x. let x = y+1 in (x,x)) - --> let x1 = y+1 in (\x. (x1,x1) - (let x=y+1 in (x,x), let x=y-1 in (x,x)) - --> let x=y+1 in let x1=y-1 in ((x,x),(x1,x1)) - -Watch out! - (let x=y+1 in let z=x+1 in (z,z) - --> matches (p,p) but watch out that the use of - x on z's rhs is OK! -I'm removing the cloning because that makes the above case -fail, because the inner let looks as if it has locally-bound vars -} - -match menv (tv_subst, id_subst, binds) e1 (Let bind e2) - | all freshly_bound bndrs, - not (any locally_bound bind_fvs) - = match (menv { me_env = rn_env' }) +match idu menv (tv_subst, id_subst, binds) e1 (Let bind e2) + | all freshly_bound bndrs -- See Note [Matching lets] + , not (any (locallyBoundR rn_env) bind_fvs) + = match idu (menv { me_env = rn_env' }) (tv_subst, id_subst, binds `snocOL` bind') e1 e2' where rn_env = me_env menv bndrs = bindersOf bind bind_fvs = varSetElems (bindFreeVars bind) - locally_bound x = inRnEnvR rn_env x freshly_bound x = not (x `rnInScope` rn_env) - bind' = bind - e2' = e2 + bind' = bind + e2' = e2 rn_env' = extendRnInScopeList rn_env bndrs -{- - (rn_env', bndrs') = mapAccumL rnBndrR rn_env bndrs - s_prs = [(bndr, Var bndr') | (bndr,bndr') <- zip bndrs bndrs', bndr /= bndr'] - subst = mkSubst (rnInScopeSet rn_env) emptyVarEnv (mkVarEnv s_prs) - (bind', e2') | null s_prs = (bind, e2) - | otherwise = (s_bind, substExpr subst e2) - s_bind = case bind of - NonRec {} -> NonRec (head bndrs') (head rhss) - Rec {} -> Rec (bndrs' `zip` map (substExpr subst) rhss) --} - -match _ subst (Lit lit1) (Lit lit2) + +match _ _ subst (Lit lit1) (Lit lit2) | lit1 == lit2 = Just subst -match menv subst (App f1 a1) (App f2 a2) - = do { subst' <- match menv subst f1 f2 - ; match menv subst' a1 a2 } +match idu menv subst (App f1 a1) (App f2 a2) + = do { subst' <- match idu menv subst f1 f2 + ; match idu menv subst' a1 a2 } -match menv subst (Lam x1 e1) (Lam x2 e2) - = match menv' subst e1 e2 +match idu menv subst (Lam x1 e1) (Lam x2 e2) + = match idu menv' subst e1 e2 where menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 } @@ -604,71 +566,46 @@ match menv subst (Lam x1 e1) (Lam x2 e2) -- It's important that this is *after* the let rule, -- so that (\x.M) ~ (let y = e in \y.N) -- does the let thing, and then gets the lam/lam rule above -match menv subst (Lam x1 e1) e2 - = match menv' subst e1 (App e2 (varToCoreExpr new_x)) +match idu menv subst (Lam x1 e1) e2 + = match idu menv' subst e1 (App e2 (varToCoreExpr new_x)) where (rn_env', new_x) = rnBndrL (me_env menv) x1 menv' = menv { me_env = rn_env' } -- Eta expansion the other way -- M ~ (\y.N) iff M y ~ N -match menv subst e1 (Lam x2 e2) - = match menv' subst (App e1 (varToCoreExpr new_x)) e2 +match idu menv subst e1 (Lam x2 e2) + = match idu menv' subst (App e1 (varToCoreExpr new_x)) e2 where (rn_env', new_x) = rnBndrR (me_env menv) x2 menv' = menv { me_env = rn_env' } -match menv subst (Case e1 x1 ty1 alts1) (Case e2 x2 ty2 alts2) +match idu menv subst (Case e1 x1 ty1 alts1) (Case e2 x2 ty2 alts2) = do { subst1 <- match_ty menv subst ty1 ty2 - ; subst2 <- match menv subst1 e1 e2 + ; subst2 <- match idu menv subst1 e1 e2 ; let menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 } - ; match_alts menv' subst2 alts1 alts2 -- Alts are both sorted + ; match_alts idu menv' subst2 alts1 alts2 -- Alts are both sorted } -match menv subst (Type ty1) (Type ty2) +match _ menv subst (Type ty1) (Type ty2) = match_ty menv subst ty1 ty2 -match menv subst (Cast e1 co1) (Cast e2 co2) +match idu menv subst (Cast e1 co1) (Cast e2 co2) = do { subst1 <- match_ty menv subst co1 co2 - ; match menv subst1 e1 e2 } - -{- REMOVING OLD CODE: I think that the above handling for let is - better than the stuff here, which looks - pretty suspicious to me. SLPJ Sept 06 --- This is an interesting rule: we simply ignore lets in the --- term being matched against! The unfolding inside it is (by assumption) --- already inside any occurrences of the bound variables, so we'll expand --- them when we encounter them. This gives a chance of matching --- forall x,y. f (g (x,y)) --- against --- f (let v = (a,b) in g v) - -match menv subst e1 (Let bind e2) - = match (menv { me_env = rn_env' }) subst e1 e2 - where - (rn_env', _bndrs') = mapAccumL rnBndrR (me_env menv) (bindersOf bind) - -- It's important to do this renaming, so that the bndrs - -- are brought into the local scope. For example: - -- Matching - -- forall f,x,xs. f (x:xs) - -- against - -- f (let y = e in (y:[])) - -- We must not get success with x->y! So we record that y is - -- locally bound (with rnBndrR), and proceed. The Var case - -- will fail when trying to bind x->y --} + ; match idu menv subst1 e1 e2 } -- Everything else fails -match _ _ _e1 _e2 = -- pprTrace "Failing at" ((text "e1:" <+> ppr e1) $$ (text "e2:" <+> ppr e2)) $ +match _ _ _ _e1 _e2 = -- pprTrace "Failing at" ((text "e1:" <+> ppr _e1) $$ (text "e2:" <+> ppr _e2)) $ Nothing ------------------------------------------ -match_var :: MatchEnv +match_var :: IdUnfoldingFun + -> MatchEnv -> SubstEnv -> Var -- Template -> CoreExpr -- Target -> Maybe SubstEnv -match_var menv subst@(tv_subst, id_subst, binds) v1 e2 +match_var idu menv subst@(tv_subst, id_subst, binds) v1 e2 | v1' `elemVarSet` me_tmpls menv = case lookupVarEnv id_subst v1' of Nothing | any (inRnEnvR rn_env) (varSetElems (exprFreeVars e2)) @@ -691,7 +628,7 @@ match_var menv subst@(tv_subst, id_subst, binds) v1 e2 -- c.f. match_ty below ; return (tv_subst', extendVarEnv id_subst v1' e2, binds) } - Just e1' | tcEqExprX (nukeRnEnvL rn_env) e1' e2 + Just e1' | eqExpr idu (nukeRnEnvL rn_env) e1' e2 -> Just subst | otherwise @@ -712,22 +649,23 @@ match_var menv subst@(tv_subst, id_subst, binds) v1 e2 ------------------------------------------ -match_alts :: MatchEnv - -> SubstEnv - -> [CoreAlt] -- Template - -> [CoreAlt] -- Target - -> Maybe SubstEnv -match_alts _ subst [] [] +match_alts :: IdUnfoldingFun + -> MatchEnv + -> SubstEnv + -> [CoreAlt] -- Template + -> [CoreAlt] -- Target + -> Maybe SubstEnv +match_alts _ _ subst [] [] = return subst -match_alts menv subst ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) +match_alts idu menv subst ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) | c1 == c2 - = do { subst1 <- match menv' subst r1 r2 - ; match_alts menv subst1 alts1 alts2 } + = do { subst1 <- match idu menv' subst r1 r2 + ; match_alts idu menv subst1 alts1 alts2 } where menv' :: MatchEnv menv' = menv { me_env = rnBndrs2 (me_env menv) vs1 vs2 } -match_alts _ _ _ _ +match_alts _ _ _ _ _ = Nothing \end{code} @@ -749,6 +687,85 @@ match_ty menv (tv_subst, id_subst, binds) ty1 ty2 ; return (tv_subst', id_subst, binds) } \end{code} +Note [Expanding variables] +~~~~~~~~~~~~~~~~~~~~~~~~~~ +Here is another Very Important rule: if the term being matched is a +variable, we expand it so long as its unfolding is "expandable". (Its +occurrence information is not necessarily up to date, so we don't use +it.) By "expandable" we mean a WHNF or a "constructor-like" application. +This is the key reason for "constructor-like" Ids. If we have + {-# NOINLINE [1] CONLIKE g #-} + {-# RULE f (g x) = h x #-} +then in the term + let v = g 3 in ....(f v).... +we want to make the rule fire, to replace (f v) with (h 3). + +Note [Do not expand locally-bound variables] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Do *not* expand locally-bound variables, else there's a worry that the +unfolding might mention variables that are themselves renamed. +Example + case x of y { (p,q) -> ...y... } +Don't expand 'y' to (p,q) because p,q might themselves have been +renamed. Essentially we only expand unfoldings that are "outside" +the entire match. + +Hence, (a) the guard (not (isLocallyBoundR v2)) + (b) when we expand we nuke the renaming envt (nukeRnEnvR). + +Note [Notes in RULE matching] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Look through Notes in both template and expression being matched. In +particular, we don't want to be confused by InlineMe notes. Maybe we +should be more careful about profiling notes, but for now I'm just +riding roughshod over them. cf Note [Notes in call patterns] in +SpecConstr + +Note [Matching lets] +~~~~~~~~~~~~~~~~~~~~ +Matching a let-expression. Consider + RULE forall x. f (g x) = +and target expression + f (let { w=R } in g E)) +Then we'd like the rule to match, to generate + let { w=R } in (\x. ) E +In effect, we want to float the let-binding outward, to enable +the match to happen. This is the WHOLE REASON for accumulating +bindings in the SubstEnv + +We can only do this if + (a) Widening the scope of w does not capture any variables + We use a conservative test: w is not already in scope + If not, we clone the binders, and substitute + (b) The free variables of R are not bound by the part of the + target expression outside the let binding; e.g. + f (\v. let w = v+1 in g E) + Here we obviously cannot float the let-binding for w. + +You may think rule (a) would never apply, because rule matching is +mostly invoked from the simplifier, when we have just run substExpr +over the argument, so there will be no shadowing anyway. +The fly in the ointment is that the forall'd variables of the +RULE itself are considered in scope. + +I though of various ways to solve (a). One plan was to +clone the binders if they are in scope. But watch out! + (let x=y+1 in let z=x+1 in (z,z) + --> should match (p,p) but watch out that + the use of x on z's rhs is OK! +If we clone x, then the let-binding for 'z' is then caught by (b), +at least unless we elaborate the RnEnv stuff a bit. + +So for we simply fail to match unless both (a) and (b) hold. + +Other cases to think about + (let x=y+1 in \x. (x,x)) + --> let x=y+1 in (\x1. (x1,x1)) + (\x. let x = y+1 in (x,x)) + --> let x1 = y+1 in (\x. (x1,x1) + (let x=y+1 in (x,x), let x=y-1 in (x,x)) + --> let x=y+1 in let x1=y-1 in ((x,x),(x1,x1)) + Note [Lookup in-scope] ~~~~~~~~~~~~~~~~~~~~~~ @@ -785,29 +802,95 @@ at all. That is why the 'lookupRnInScope' call in the (Var v2) case of 'match' is so important. +\begin{code} +eqExpr :: IdUnfoldingFun -> RnEnv2 -> CoreExpr -> CoreExpr -> Bool +-- ^ A kind of shallow equality used in rule matching, so does +-- /not/ look through newtypes or predicate types + +eqExpr _ env (Var v1) (Var v2) + | rnOccL env v1 == rnOccR env v2 + = True + +-- The next two rules expand non-local variables +-- C.f. Note [Expanding variables] +-- and Note [Do not expand locally-bound variables] +eqExpr id_unfolding_fun env (Var v1) e2 + | not (locallyBoundL env v1) + , Just e1' <- expandUnfolding (id_unfolding_fun (lookupRnInScope env v1)) + = eqExpr id_unfolding_fun (nukeRnEnvL env) e1' e2 + +eqExpr id_unfolding_fun env e1 (Var v2) + | not (locallyBoundR env v2) + , Just e2' <- expandUnfolding (id_unfolding_fun (lookupRnInScope env v2)) + = eqExpr id_unfolding_fun (nukeRnEnvR env) e1 e2' + +eqExpr _ _ (Lit lit1) (Lit lit2) = lit1 == lit2 +eqExpr idu env (App f1 a1) (App f2 a2) = eqExpr idu env f1 f2 && eqExpr idu env a1 a2 +eqExpr idu env (Lam v1 e1) (Lam v2 e2) = eqExpr idu (rnBndr2 env v1 v2) e1 e2 +eqExpr idu env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && eqExpr idu env e1 e2 +eqExpr idu env (Cast e1 co1) (Cast e2 co2) = tcEqTypeX env co1 co2 && eqExpr idu env e1 e2 +eqExpr _ env (Type t1) (Type t2) = tcEqTypeX env t1 t2 + +eqExpr idu env (Let (NonRec v1 r1) e1) + (Let (NonRec v2 r2) e2) = eqExpr idu env r1 r2 + && eqExpr idu (rnBndr2 env v1 v2) e1 e2 +eqExpr idu env (Let (Rec ps1) e1) + (Let (Rec ps2) e2) = equalLength ps1 ps2 + && and (zipWith eq_rhs ps1 ps2) + && eqExpr idu env' e1 e2 + where + env' = foldl2 rn_bndr2 env ps2 ps2 + rn_bndr2 env (b1,_) (b2,_) = rnBndr2 env b1 b2 + eq_rhs (_,r1) (_,r2) = eqExpr idu env' r1 r2 +eqExpr idu env (Case e1 v1 t1 a1) + (Case e2 v2 t2 a2) = eqExpr idu env e1 e2 + && tcEqTypeX env t1 t2 + && equalLength a1 a2 + && and (zipWith eq_alt a1 a2) + where + env' = rnBndr2 env v1 v2 + eq_alt (c1,vs1,r1) (c2,vs2,r2) + = c1==c2 && eqExpr idu (rnBndrs2 env' vs1 vs2) r1 r2 +eqExpr _ _ _ _ = False + +eq_note :: RnEnv2 -> Note -> Note -> Bool +eq_note _ (SCC cc1) (SCC cc2) = cc1 == cc2 +eq_note _ (CoreNote s1) (CoreNote s2) = s1 == s2 +eq_note _ _ _ = False +\end{code} + +Auxiliary functions + +\begin{code} +locallyBoundL, locallyBoundR :: RnEnv2 -> Var -> Bool +locallyBoundL rn_env v = inRnEnvL rn_env v +locallyBoundR rn_env v = inRnEnvR rn_env v + + +expandUnfolding :: Unfolding -> Maybe CoreExpr +expandUnfolding unfolding + | isExpandableUnfolding unfolding = Just (unfoldingTemplate unfolding) + | otherwise = Nothing +\end{code} %************************************************************************ %* * -\subsection{Checking a program for failing rule applications} + Rule-check the program %* * %************************************************************************ ------------------------------------------------------ - Game plan ------------------------------------------------------ - -We want to know what sites have rules that could have fired but didn't. -This pass runs over the tree (without changing it) and reports such. + We want to know what sites have rules that could have fired but didn't. + This pass runs over the tree (without changing it) and reports such. \begin{code} -- | Report partial matches for rules beginning with the specified -- string for the purposes of error reporting -ruleCheckProgram :: (Activation -> Bool) -- ^ Rule activation test +ruleCheckProgram :: CompilerPhase -- ^ Rule activation test -> String -- ^ Rule pattern -> RuleBase -- ^ Database of rules -> [CoreBind] -- ^ Bindings to check in -> SDoc -- ^ Resulting check message -ruleCheckProgram is_active rule_pat rule_base binds +ruleCheckProgram phase rule_pat rule_base binds | isEmptyBag results = text "Rule check results: no rule application sites" | otherwise @@ -816,11 +899,17 @@ ruleCheckProgram is_active rule_pat rule_base binds vcat [ p $$ line | p <- bagToList results ] ] where - results = unionManyBags (map (ruleCheckBind (RuleCheckEnv is_active rule_pat rule_base)) binds) + env = RuleCheckEnv { rc_is_active = isActive phase + , rc_id_unf = idUnfolding -- Not quite right + -- Should use activeUnfolding + , rc_pattern = rule_pat + , rc_rule_base = rule_base } + results = unionManyBags (map (ruleCheckBind env) binds) line = text (replicate 20 '-') data RuleCheckEnv = RuleCheckEnv { rc_is_active :: Activation -> Bool, + rc_id_unf :: IdUnfoldingFun, rc_pattern :: String, rc_rule_base :: RuleBase } @@ -855,13 +944,13 @@ ruleCheckFun :: RuleCheckEnv -> Id -> [CoreExpr] -> Bag SDoc ruleCheckFun env fn args | null name_match_rules = emptyBag - | otherwise = unitBag (ruleAppCheck_help (rc_is_active env) fn args name_match_rules) + | otherwise = unitBag (ruleAppCheck_help env fn args name_match_rules) where name_match_rules = filter match (getRules (rc_rule_base env) fn) match rule = (rc_pattern env) `isPrefixOf` unpackFS (ruleName rule) -ruleAppCheck_help :: (Activation -> Bool) -> Id -> [CoreExpr] -> [CoreRule] -> SDoc -ruleAppCheck_help is_active fn args rules +ruleAppCheck_help :: RuleCheckEnv -> Id -> [CoreExpr] -> [CoreRule] -> SDoc +ruleAppCheck_help env fn args rules = -- The rules match the pattern, so we want to print something vcat [text "Expression:" <+> ppr (mkApps (Var fn) args), vcat (map check_rule rules)] @@ -878,14 +967,14 @@ ruleAppCheck_help is_active fn args rules = ptext (sLit "Rule") <+> doubleQuotes (ftext name) rule_info rule - | Just _ <- matchRule noBlackList emptyInScopeSet args rough_args rule + | Just _ <- matchRule noBlackList (rc_id_unf env) emptyInScopeSet args rough_args rule = text "matches (which is very peculiar!)" rule_info (BuiltinRule {}) = text "does not match" rule_info (Rule { ru_act = act, ru_bndrs = rule_bndrs, ru_args = rule_args}) - | not (is_active act) = text "active only in later phase" + | not (rc_is_active env act) = text "active only in later phase" | n_args < n_rule_args = text "too few arguments" | n_mismatches == n_rule_args = text "no arguments match" | n_mismatches == 0 = text "all arguments match (considered individually), but rule as a whole does not" @@ -897,7 +986,7 @@ ruleAppCheck_help is_active fn args rules not (isJust (match_fn rule_arg arg))] lhs_fvs = exprsFreeVars rule_args -- Includes template tyvars - match_fn rule_arg arg = match menv emptySubstEnv rule_arg arg + match_fn rule_arg arg = match (rc_id_unf env) menv emptySubstEnv rule_arg arg where in_scope = lhs_fvs `unionVarSet` exprFreeVars arg menv = ME { me_env = mkRnEnv2 (mkInScopeSet in_scope)