X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Fspecialise%2FRules.lhs;h=6bb2eb1424d9ca595739208664193b8e47ae0ca9;hb=9512557e2ad1800146ff1931748cda283c267026;hp=19bced3241b259198f6ad9abaeb70ec55c5ec58d;hpb=7c3d4a1f2b2529ce300b8acc1d26ad98312b9e96;p=ghc-hetmet.git diff --git a/ghc/compiler/specialise/Rules.lhs b/ghc/compiler/specialise/Rules.lhs index 19bced3..6bb2eb1 100644 --- a/ghc/compiler/specialise/Rules.lhs +++ b/ghc/compiler/specialise/Rules.lhs @@ -5,41 +5,46 @@ \begin{code} module Rules ( - RuleBase, emptyRuleBase, - extendRuleBase, extendRuleBaseList, - ruleBaseIds, getLocalRules, - pprRuleBase, ruleCheckProgram, + RuleBase, emptyRuleBase, mkRuleBase, extendRuleBaseList, + unionRuleBase, pprRuleBase, ruleCheckProgram, - lookupRule, addRule, addIdSpecialisations + mkSpecInfo, extendSpecInfo, addSpecInfo, + rulesOfBinds, addIdSpecialisations, + + lookupRule, mkLocalRule, roughTopNames ) where #include "HsVersions.h" import CoreSyn -- All of it -import OccurAnal ( occurAnalyseRule ) -import CoreFVs ( exprFreeVars, ruleRhsFreeVars ) +import OccurAnal ( occurAnalyseExpr ) +import CoreFVs ( exprFreeVars, exprsFreeVars, rulesRhsFreeVars ) import CoreUnfold ( isCheapUnfolding, unfoldingTemplate ) -import CoreUtils ( eqExpr ) -import CoreTidy ( pprTidyIdRules ) -import Subst ( Subst, InScopeSet, mkInScopeSet, lookupSubst, extendSubst, - substEnv, setSubstEnv, emptySubst, isInScope, emptyInScopeSet, - bindSubstList, unBindSubstList, substInScope, uniqAway - ) -import Id ( Id, idIsFrom, idUnfolding, idSpecialisation, setIdSpecialisation ) -import Var ( isId ) +import CoreUtils ( tcEqExprX ) +import PprCore ( pprRules ) +import Type ( Type ) +import TcType ( tcSplitTyConApp_maybe ) +import CoreTidy ( tidyRules ) +import Id ( Id, idUnfolding, isLocalId, isGlobalId, idName, + idSpecialisation, idCoreRules, setIdSpecialisation ) +import IdInfo ( SpecInfo( SpecInfo ) ) +import Var ( Var ) +import VarEnv ( IdEnv, TyVarEnv, InScopeSet, emptyTidyEnv, + emptyInScopeSet, mkInScopeSet, extendInScopeSetList, + emptyVarEnv, lookupVarEnv, extendVarEnv, + nukeRnEnvL, mkRnEnv2, rnOccR, rnOccL, inRnEnvR, + rnBndrR, rnBndr2, rnBndrL, rnBndrs2 ) import VarSet -import VarEnv -import TcType ( mkTyVarTy ) -import qualified TcType ( match ) +import Name ( Name, NamedThing(..), nameOccName ) +import NameEnv +import Unify ( ruleMatchTyX, MatchEnv(..) ) import BasicTypes ( Activation, CompilerPhase, isActive ) -import Module ( Module ) - import Outputable import FastString -import Maybe ( isJust, isNothing, fromMaybe ) -import Util ( sortLt ) +import Maybes ( isJust, orElse ) import Bag -import List ( isPrefixOf, partition ) +import Util ( singleton ) +import List ( isPrefixOf ) \end{code} @@ -77,6 +82,107 @@ might have a specialisation where pi' :: Lift Int# is the specialised version of pi. +\begin{code} +mkLocalRule :: RuleName -> Activation + -> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule +-- Used to make CoreRule for an Id defined in this module +mkLocalRule 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_orph = Just (nameOccName fn), ru_local = True } + +-------------- +roughTopNames :: [CoreExpr] -> [Maybe Name] +roughTopNames args = map roughTopName args + +roughTopName :: CoreExpr -> Maybe Name +-- Find the "top" free name of an expression +-- a) the function in an App chain (if a GlobalId) +-- b) the TyCon in a type +-- This is used for the fast-match-check for rules; +-- if the top names don't match, the rest can't +roughTopName (Type ty) = case tcSplitTyConApp_maybe ty of + Just (tc,_) -> Just (getName tc) + Nothing -> Nothing +roughTopName (App f a) = roughTopName f +roughTopName (Var f) | isGlobalId f = Just (idName f) + | otherwise = Nothing +roughTopName other = Nothing + +ruleCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool +-- (ruleCantMatch tpl actual) returns True only if 'actual' +-- definitely can't match 'tpl' by instantiating 'tpl'. +-- It's only a one-way match; unlike instance matching we +-- don't consider unification +ruleCantMatch (Just n1 : ts) (Just n2 : as) = n1 /= n2 || ruleCantMatch ts as +ruleCantMatch (Just n1 : ts) (Nothing : as) = True +ruleCantMatch (t : ts) (a : as) = ruleCantMatch ts as +ruleCantMatch ts as = False +\end{code} + + +%************************************************************************ +%* * + SpecInfo: the rules in an IdInfo +%* * +%************************************************************************ + +\begin{code} +mkSpecInfo :: [CoreRule] -> SpecInfo +mkSpecInfo rules = SpecInfo rules (rulesRhsFreeVars rules) + +extendSpecInfo :: SpecInfo -> [CoreRule] -> SpecInfo +extendSpecInfo (SpecInfo rs1 fvs1) rs2 + = SpecInfo (rs2 ++ rs1) (rulesRhsFreeVars rs2 `unionVarSet` fvs1) + +addSpecInfo :: SpecInfo -> SpecInfo -> SpecInfo +addSpecInfo (SpecInfo rs1 fvs1) (SpecInfo rs2 fvs2) + = SpecInfo (rs1 ++ rs2) (fvs1 `unionVarSet` fvs2) + +addIdSpecialisations :: Id -> [CoreRule] -> Id +addIdSpecialisations id rules + = setIdSpecialisation id $ + extendSpecInfo (idSpecialisation id) rules + +rulesOfBinds :: [CoreBind] -> [CoreRule] +rulesOfBinds binds = concatMap (concatMap idCoreRules . bindersOf) binds +\end{code} + + +%************************************************************************ +%* * + RuleBase +%* * +%************************************************************************ + +\begin{code} +type RuleBase = NameEnv [CoreRule] + -- Maps (the name of) an Id to its rules + -- The rules are are unordered; + -- we sort out any overlaps on lookup + +emptyRuleBase = emptyNameEnv + +mkRuleBase :: [CoreRule] -> RuleBase +mkRuleBase rules = extendRuleBaseList emptyRuleBase rules + +extendRuleBaseList :: RuleBase -> [CoreRule] -> RuleBase +extendRuleBaseList rule_base new_guys + = foldl extendRuleBase rule_base new_guys + +unionRuleBase :: RuleBase -> RuleBase -> RuleBase +unionRuleBase rb1 rb2 = plusNameEnv_C (++) rb1 rb2 + +extendRuleBase :: RuleBase -> CoreRule -> RuleBase +extendRuleBase rule_base rule + = extendNameEnv_Acc (:) singleton rule_base (ruleIdName rule) rule + +pprRuleBase :: RuleBase -> SDoc +pprRuleBase rules = vcat [ pprRules (tidyRules emptyTidyEnv rs) + | rs <- nameEnvElts rules ] +\end{code} + %************************************************************************ %* * @@ -85,20 +191,77 @@ where pi' :: Lift Int# is the specialised version of pi. %************************************************************************ \begin{code} +lookupRule :: (Activation -> Bool) -> InScopeSet + -> RuleBase -- Imported rules + -> Id -> [CoreExpr] -> Maybe (RuleName, CoreExpr) +lookupRule is_active in_scope rule_base fn args + = matchRules is_active in_scope fn args rules + where + -- 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) + rules = extra_rules ++ idCoreRules fn + extra_rules | isLocalId fn = [] + | otherwise = lookupNameEnv rule_base (idName fn) `orElse` [] + matchRules :: (Activation -> Bool) -> InScopeSet - -> [CoreRule] -> [CoreExpr] -> Maybe (RuleName, CoreExpr) + -> Id -> [CoreExpr] + -> [CoreRule] -> Maybe (RuleName, CoreExpr) -- See comments on matchRule -matchRules is_active in_scope [] args = Nothing -matchRules is_active in_scope (rule:rules) args - = case matchRule is_active in_scope rule args of - Just result -> Just result - Nothing -> matchRules is_active in_scope rules args +matchRules is_active in_scope fn args rules + = case go [] rules of + [] -> Nothing + (m:ms) -> Just (case findBest (fn,args) m ms of + (rule, ans) -> (ru_name rule, ans)) + where + rough_args = map roughTopName args + + go :: [(CoreRule,CoreExpr)] -> [CoreRule] -> [(CoreRule,CoreExpr)] + go ms [] = ms + go ms (r:rs) = case (matchRule is_active in_scope args rough_args r) of + Just e -> go ((r,e):ms) rs + Nothing -> go ms rs + +findBest :: (Id, [CoreExpr]) + -> (CoreRule,CoreExpr) -> [(CoreRule,CoreExpr)] -> (CoreRule,CoreExpr) +-- All these pairs matched the expression +-- Return the pair the the most specific rule +-- The (fn,args) is just for overlap reporting + +findBest target (rule,ans) [] = (rule,ans) +findBest target (rule1,ans1) ((rule2,ans2):prs) + | rule1 `isMoreSpecific` rule2 = findBest target (rule1,ans1) prs + | rule2 `isMoreSpecific` rule1 = findBest target (rule1,ans1) prs +#ifdef DEBUG + | otherwise = pprTrace "Rules.findBest: rule overlap (Rule 1 wins)" + (vcat [ptext SLIT("Expression to match:") <+> ppr fn <+> sep (map ppr args), + ptext SLIT("Rule 1:") <+> ppr rule1, + ptext SLIT("Rule 2:") <+> ppr rule2]) $ + findBest target (rule1,ans1) prs +#else + | otherwise = findBest target (rule1,ans1) prs +#endif + where + (fn,args) = target + +isMoreSpecific :: CoreRule -> CoreRule -> Bool +isMoreSpecific (BuiltinRule {}) r2 = True +isMoreSpecific r1 (BuiltinRule {}) = False +isMoreSpecific (Rule { ru_bndrs = bndrs1, ru_args = args1 }) + (Rule { ru_bndrs = bndrs2, ru_args = args2 }) + = isJust (matchN in_scope bndrs2 args2 args1) + where + in_scope = mkInScopeSet (mkVarSet bndrs1) + -- Actually we should probably include the free vars + -- of rule1's args, but I can't be bothered noBlackList :: Activation -> Bool noBlackList act = False -- Nothing is black listed matchRule :: (Activation -> Bool) -> InScopeSet - -> CoreRule -> [CoreExpr] -> Maybe (RuleName, CoreExpr) + -> [CoreExpr] -> [Maybe Name] + -> CoreRule -> Maybe CoreExpr -- If (matchRule rule args) returns Just (name,rhs) -- then (f args) matches the rule, and the corresponding @@ -121,262 +284,225 @@ matchRule :: (Activation -> Bool) -> InScopeSet -- -- Any 'surplus' arguments in the input are simply put on the end -- of the output. --- --- ASSUMPTION (A): --- A1. No top-level variable is bound in the target --- A2. No template variable is bound in the target --- A3. No lambda bound template variable is free in any subexpression of the target --- --- To see why A1 is necessary, consider matching --- \x->f against \f->f --- When we meet the lambdas we substitute [f/x] in the template (a no-op), --- and then erroneously succeed in matching f against f. --- --- To see why A2 is needed consider matching --- forall a. \b->b against \a->3 --- When we meet the lambdas we substitute [a/b] in the template, and then --- erroneously succeed in matching what looks like the template variable 'a' against 3. --- --- A3 is needed to validate the rule that says --- (\x->E) matches F --- if --- (\x->E) matches (\x->F x) - -matchRule is_active in_scope rule@(BuiltinRule name match_fn) args +matchRule is_active in_scope args rough_args + (BuiltinRule { ru_name = name, ru_try = match_fn }) = case match_fn args of - Just expr -> Just (name,expr) + Just expr -> Just expr Nothing -> Nothing -matchRule is_active in_scope rule@(Rule rn act tpl_vars tpl_args rhs) args - | not (is_active act) - = Nothing +matchRule is_active in_scope args rough_args + (Rule { ru_name = rn, 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 - = go tpl_args args emptySubst - -- We used to use the in_scope set, but I don't think that's necessary - -- After all, the result is going to be simplified again with that in_scope set - where - tpl_var_set = mkVarSet tpl_vars - - ----------------------- - -- Do the business - go (tpl_arg:tpl_args) (arg:args) subst = match tpl_arg arg tpl_var_set (go tpl_args args) subst - - -- Two easy ways to terminate - go [] [] subst = Just (rn, app_match subst (mkLams tpl_vars rhs) tpl_vars) - go [] args subst = Just (rn, app_match subst (mkLams tpl_vars rhs) tpl_vars `mkApps` args) - - -- One tiresome way to terminate: check for excess unmatched - -- template arguments - go tpl_args [] subst = Nothing -- Failure - - - ----------------------- - app_match subst fn vs = foldl go fn vs - where - senv = substEnv subst - go fn v = case lookupSubstEnv senv v of - Just (DoneEx ex) -> fn `App` ex - Just (DoneTy ty) -> fn `App` Type ty - -- Substitution should bind them all! - - - ----------------------- -{- The code below tries to match even if there are more - template args than real args. - - I now think this is probably a bad idea. - Should the template (map f xs) match (map g)? I think not. - For a start, in general eta expansion wastes work. - SLPJ July 99 - - = case eta_complete tpl_args (mkVarSet leftovers) of - Just leftovers' -> Just (rn, mkLams done (mkLams leftovers' rhs), - mk_result_args subst done) - Nothing -> Nothing -- Failure - where - (done, leftovers) = partition (\v -> isJust (lookupSubstEnv subst_env v)) - (map zapOccInfo tpl_vars) - -- Zap the occ info - subst_env = substEnv subst - - ----------------------- - eta_complete [] vars = ASSERT( isEmptyVarSet vars ) - Just [] - eta_complete (Type ty:tpl_args) vars - = case getTyVar_maybe ty of - Just tv | tv `elemVarSet` vars - -> case eta_complete tpl_args (vars `delVarSet` tv) of - Just vars' -> Just (tv:vars') - Nothing -> Nothing - other -> Nothing - - eta_complete (Var v:tpl_args) vars - | v `elemVarSet` vars - = case eta_complete tpl_args (vars `delVarSet` v) of - Just vars' -> Just (v:vars') - Nothing -> Nothing - - eta_complete other vars = Nothing - - -zapOccInfo bndr | isTyVar bndr = bndr - | otherwise = zapLamIdInfo bndr --} + = case matchN in_scope tpl_vars tpl_args args of + Nothing -> Nothing + Just (tpl_vals, leftovers) -> Just (rule_fn + `mkApps` tpl_vals + `mkApps` leftovers) + where + rule_fn = occurAnalyseExpr (mkLams tpl_vars rhs) + -- We could do this when putting things into the rulebase, I guess \end{code} \begin{code} -type Matcher result = VarSet -- Template variables - -> (Subst -> Maybe result) -- Continuation if success - -> Subst -> Maybe result -- Substitution so far -> result --- The *SubstEnv* in these Substs apply to the TEMPLATE only +matchN :: InScopeSet + -> [Var] -- Template tyvars + -> [CoreExpr] -- Template + -> [CoreExpr] -- Target; can have more elts than template + -> Maybe ([CoreExpr], -- What is substituted for each template var + [CoreExpr]) -- Leftover target exprs + +matchN in_scope tmpl_vars tmpl_es target_es + = do { (subst, leftover_es) <- go init_menv emptySubstEnv tmpl_es target_es + ; return (map (lookup_tmpl subst) tmpl_vars, leftover_es) } + where + init_menv = ME { me_tmpls = mkVarSet tmpl_vars, me_env = init_rn_env } + init_rn_env = mkRnEnv2 (extendInScopeSetList in_scope tmpl_vars) + + go menv subst [] es = Just (subst, es) + go menv subst ts [] = Nothing -- Fail if too few actual args + go menv subst (t:ts) (e:es) = do { subst1 <- match menv subst t e + ; go menv subst1 ts es } + + lookup_tmpl :: (TvSubstEnv, IdSubstEnv) -> Var -> CoreExpr + lookup_tmpl (tv_subst, id_subst) tmpl_var + | isTyVar tmpl_var = case lookupVarEnv tv_subst tmpl_var of + Just ty -> Type ty + Nothing -> unbound tmpl_var + | otherwise = case lookupVarEnv id_subst tmpl_var of + Just e -> e + other -> unbound tmpl_var + + unbound var = pprPanic "Template variable unbound in rewrite rule" (ppr var) +\end{code} --- The *InScopeSet* in these Substs gives variables bound so far in the --- target term. So when matching forall a. (\x. a x) against (\y. y y) --- while processing the body of the lambdas, the in-scope set will be {y}. --- That lets us do the occurs-check when matching 'a' against 'y' -match :: CoreExpr -- Template - -> CoreExpr -- Target - -> Matcher result + --------------------------------------------- + The inner workings of matching + --------------------------------------------- + +\begin{code} +-- These two definitions are not the same as in Subst, +-- but they simple and direct, and purely local to this module +-- The third, for TvSubstEnv, is the same as in VarEnv, but repeated here +-- for uniformity with IdSubstEnv +type SubstEnv = (TvSubstEnv, IdSubstEnv) +type IdSubstEnv = IdEnv CoreExpr +type TvSubstEnv = TyVarEnv Type -match_fail = Nothing +emptySubstEnv :: SubstEnv +emptySubstEnv = (emptyVarEnv, emptyVarEnv) -match (Var v1) e2 tpl_vars kont subst - = case lookupSubst subst v1 of - Nothing | v1 `elemVarSet` tpl_vars -- v1 is a template variable - -> if (any (`isInScope` subst) (varSetElems (exprFreeVars e2))) then - match_fail -- Occurs check failure - -- e.g. match forall a. (\x-> a x) against (\y. y y) - else - kont (extendSubst subst v1 (DoneEx e2)) +-- At one stage I tried to match even if there are more +-- template args than real args. + +-- I now think this is probably a bad idea. +-- Should the template (map f xs) match (map g)? I think not. +-- For a start, in general eta expansion wastes work. +-- SLPJ July 99 + + +match :: MatchEnv + -> SubstEnv + -> CoreExpr -- Template + -> CoreExpr -- Target + -> Maybe SubstEnv - | eqExpr (Var v1) e2 -> kont subst - -- v1 is not a template variable, so it must be a global constant +-- See the notes with Unify.match, which matches types +-- Everything is very similar for terms - Just (DoneEx e2') | eqExpr e2' e2 -> kont subst +-- Interesting examples: +-- Consider matching +-- \x->f against \f->f +-- When we meet the lambdas we must remember to rename f to f' in the +-- second expresion. The RnEnv2 does that. +-- +-- Consider matching +-- forall a. \b->b against \a->3 +-- We must rename the \a. Otherwise when we meet the lambdas we +-- might substitute [a/b] in the template, and then erroneously +-- 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@(tv_subst, id_subst) (Var v1) e2 + | v1 `elemVarSet` me_tmpls menv + = case lookupVarEnv id_subst v1' of + Nothing | any (inRnEnvR rn_env) (varSetElems (exprFreeVars e2)) + -> Nothing -- Occurs check failure + -- e.g. match forall a. (\x-> a x) against (\y. y y) + + | otherwise + -> Just (tv_subst, extendVarEnv id_subst v1 e2) + + Just e2' | tcEqExprX (nukeRnEnvL rn_env) e2' e2 + -> Just subst + + other -> Nothing + + | otherwise -- v1 is not a template variable + = case e2 of + Var v2 | v1' == rnOccR rn_env v2 -> Just subst + other -> Nothing + where + rn_env = me_env menv + v1' = rnOccL rn_env v1 - other -> match_fail +-- 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) + where + unfolding = idUnfolding v2 -match (Lit lit1) (Lit lit2) tpl_vars kont subst +match menv subst (Lit lit1) (Lit lit2) | lit1 == lit2 - = kont subst + = Just subst -match (App f1 a1) (App f2 a2) tpl_vars kont subst - = match f1 f2 tpl_vars (match a1 a2 tpl_vars kont) subst +match menv subst (App f1 a1) (App f2 a2) + = do { subst' <- match menv subst f1 f2 + ; match menv subst' a1 a2 } -match (Lam x1 e1) (Lam x2 e2) tpl_vars kont subst - = bind [x1] [x2] (match e1 e2) tpl_vars kont subst +match menv subst (Lam x1 e1) (Lam x2 e2) + = match menv' subst e1 e2 + where + menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 } -- This rule does eta expansion -- (\x.M) ~ N iff M ~ N x --- See assumption A3 -match (Lam x1 e1) e2 tpl_vars kont subst - = bind [x1] [x1] (match e1 (App e2 (mkVarArg x1))) tpl_vars kont subst +match menv subst (Lam x1 e1) e2 + = match 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 \y.M y ~ \y.N --- iff M y ~ N --- Remembering that by (A), y can't be free in M, we get this -match e1 (Lam x2 e2) tpl_vars kont subst - = bind [new_id] [x2] (match (App e1 (mkVarArg new_id)) e2) tpl_vars kont subst - where - new_id = uniqAway (substInScope subst) x2 - -- This uniqAway is actually needed. Here's the example: - -- rule: foldr (mapFB (:) f) [] = mapList - -- target: foldr (\x. mapFB k f x) [] - -- where - -- k = \x. mapFB ... x - -- The first \x is ok, but when we inline k, hoping it might - -- match (:) we find a second \x. - -match (Case e1 x1 alts1) (Case e2 x2 alts2) tpl_vars kont subst - = match e1 e2 tpl_vars case_kont subst +-- M ~ (\y.N) iff M y ~ N +match menv subst e1 (Lam x2 e2) + = match menv' subst (App e1 (varToCoreExpr new_x)) e2 where - case_kont subst = bind [x1] [x2] (match_alts alts1 (sortLt lt_alt alts2)) - tpl_vars kont subst + (rn_env', new_x) = rnBndrR (me_env menv) x2 + menv' = menv { me_env = rn_env' } -match (Type ty1) (Type ty2) tpl_vars kont subst - = match_ty ty1 ty2 tpl_vars kont subst +match 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 + ; let menv' = menv { me_env = rnBndr2 (me_env menv) x2 x2 } + ; match_alts menv' subst2 alts1 alts2 -- Alts are both sorted + } -match (Note (Coerce to1 from1) e1) (Note (Coerce to2 from2) e2) - tpl_vars kont subst - = (match_ty to1 to2 tpl_vars $ - match_ty from1 from2 tpl_vars $ - match e1 e2 tpl_vars kont) subst +match menv subst (Type ty1) (Type ty2) + = match_ty menv subst ty1 ty2 - -{- I don't buy this let-rule any more - The let rule fails on matching - forall f,x,xs. f (x:xs) - against - f (let y = e in (y:[])) - because we just get x->y, which is bogus. +match menv subst (Note (Coerce to1 from1) e1) (Note (Coerce to2 from2) e2) + = do { subst1 <- match_ty menv subst to1 to2 + ; subst2 <- match_ty menv subst1 from1 from2 + ; match menv subst2 e1 e2 } -- 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. Meanwhile, we can't get false matches because --- (also by assumption) the term being matched has no shadowing. -match e1 (Let bind e2) tpl_vars kont subst - = match e1 e2 tpl_vars kont subst --} - --- 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 e1 (Var v2) tpl_vars kont subst - | isCheapUnfolding unfolding - = match e1 (unfoldingTemplate unfolding) tpl_vars kont subst +-- them when we encounter them. +match menv subst e1 (Let (NonRec x2 r2) e2) + = match menv' subst e1 e2 where - unfolding = idUnfolding v2 - - --- We can't cope with lets in the template - -match e1 e2 tpl_vars kont subst = match_fail - + menv' = menv { me_env = fst (rnBndrR (me_env menv) x2) } + -- It's important to do this renaming. 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! Instead, we + -- need an occurs check. + +-- Everything else fails +match menv subst e1 e2 = Nothing ------------------------------------------ -match_alts [] [] tpl_vars kont subst - = kont subst -match_alts ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) tpl_vars kont subst +match_alts :: MatchEnv + -> SubstEnv + -> [CoreAlt] -- Template + -> [CoreAlt] -- Target + -> Maybe SubstEnv +match_alts menv subst [] [] + = return subst +match_alts menv subst ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) | c1 == c2 - = bind vs1 vs2 (match r1 r2) tpl_vars - (match_alts alts1 alts2 tpl_vars kont) - subst -match_alts alts1 alts2 tpl_vars kont subst = match_fail - -lt_alt (con1, _, _) (con2, _, _) = con1 < con2 - ----------------------------------------- -bind :: [CoreBndr] -- Template binders - -> [CoreBndr] -- Target binders - -> Matcher result - -> Matcher result --- This makes uses of assumption (A) above. For example, --- this would fail: --- Template: (\x.y) (y is free) --- Target : (\y.y) (y is bound) --- We rename x to y in the template... but then erroneously --- match y against y. But this can't happen because of (A) -bind vs1 vs2 matcher tpl_vars kont subst - = WARN( not (all not_in_subst vs1), bug_msg ) - matcher tpl_vars kont' subst' + = do { subst1 <- match menv' subst r1 r2 + ; match_alts menv subst1 alts1 alts2 } where - kont' subst'' = kont (unBindSubstList subst'' vs1 vs2) - subst' = bindSubstList subst vs1 vs2 - - -- The unBindSubst relies on no shadowing in the template - not_in_subst v = isNothing (lookupSubst subst v) - bug_msg = sep [ppr vs1, ppr vs2] + menv' :: MatchEnv + menv' = menv { me_env = rnBndrs2 (me_env menv) vs1 vs2 } ----------------------------------------- -mkVarArg :: CoreBndr -> CoreArg -mkVarArg v | isId v = Var v - | otherwise = Type (mkTyVarTy v) +match_alts menv subst alts1 alts2 + = Nothing \end{code} Matching Core types: use the matcher in TcType. @@ -386,84 +512,10 @@ we have a specialised version of a function at a newtype, say We only want to replace (f T) with f', not (f Int). \begin{code} ----------------------------------------- -match_ty ty1 ty2 tpl_vars kont subst - = TcType.match ty1 ty2 tpl_vars kont' (substEnv subst) - where - kont' senv = kont (setSubstEnv subst senv) -\end{code} - - - -%************************************************************************ -%* * -\subsection{Adding a new rule} -%* * -%************************************************************************ - -\begin{code} -addRule :: Id -> CoreRules -> CoreRule -> CoreRules - --- Add a new rule to an existing bunch of rules. --- The rules are for the given Id; the Id argument is needed only --- so that we can exclude the Id from its own RHS free-var set - --- Insert the new rule just before a rule that is *less specific* --- than the new one; or at the end if there isn't such a one. --- In this way we make sure that when looking up, the first match --- is the most specific. --- --- We make no check for rules that unify without one dominating --- the other. Arguably this would be a bug. - -addRule id (Rules rules rhs_fvs) rule@(BuiltinRule _ _) - = Rules (rule:rules) rhs_fvs - -- Put it at the start for lack of anything better - -addRule id (Rules rules rhs_fvs) rule - = Rules (insertRule rules new_rule) (rhs_fvs `unionVarSet` new_rhs_fvs) - where - new_rule = occurAnalyseRule rule - new_rhs_fvs = ruleRhsFreeVars new_rule `delVarSet` id - -- Hack alert! - -- Don't include the Id in its own rhs free-var set. - -- Otherwise the occurrence analyser makes bindings recursive - -- that shoudn't be. E.g. - -- RULE: f (f x y) z ==> f x (f y z) - -insertRule rules new_rule@(Rule _ _ tpl_vars tpl_args _) - = go rules - where - tpl_var_set = mkInScopeSet (mkVarSet tpl_vars) - -- Actually we should probably include the free vars of tpl_args, - -- but I can't be bothered - - go [] = [new_rule] - go (rule:rules) | new_is_more_specific rule = (new_rule:rule:rules) - | otherwise = rule : go rules - - new_is_more_specific rule = isJust (matchRule noBlackList tpl_var_set rule tpl_args) - -addIdSpecialisations :: Id -> [CoreRule] -> Id -addIdSpecialisations id rules - = setIdSpecialisation id new_specs - where - new_specs = foldl (addRule id) (idSpecialisation id) rules -\end{code} - - -%************************************************************************ -%* * -\subsection{Looking up a rule} -%* * -%************************************************************************ - -\begin{code} -lookupRule :: (Activation -> Bool) -> InScopeSet - -> Id -> [CoreExpr] -> Maybe (RuleName, CoreExpr) -lookupRule is_active in_scope fn args - = case idSpecialisation fn of - Rules rules _ -> matchRules is_active in_scope rules args +------------------------------------------ +match_ty menv (tv_subst, id_subst) ty1 ty2 + = do { tv_subst' <- Unify.ruleMatchTyX menv tv_subst ty1 ty2 + ; return (tv_subst', id_subst) } \end{code} @@ -516,8 +568,8 @@ ruleCheck env (App f a) = ruleCheckApp env (App f a) [] ruleCheck env (Note n e) = ruleCheck env e ruleCheck env (Let bd e) = ruleCheckBind env bd `unionBags` ruleCheck env e ruleCheck env (Lam b e) = ruleCheck env e -ruleCheck env (Case e _ as) = ruleCheck env e `unionBags` - unionManyBags [ruleCheck env r | (_,_,r) <- as] +ruleCheck env (Case e _ _ as) = ruleCheck env e `unionBags` + unionManyBags [ruleCheck env r | (_,_,r) <- as] ruleCheckApp env (App f a) as = ruleCheck env a `unionBags` ruleCheckApp env f (a:as) ruleCheckApp env (Var f) as = ruleCheckFun env f as @@ -533,8 +585,7 @@ ruleCheckFun (phase, pat) fn args | null name_match_rules = emptyBag | otherwise = unitBag (ruleAppCheck_help phase fn args name_match_rules) where - name_match_rules = case idSpecialisation fn of - Rules rules _ -> filter match rules + name_match_rules = filter match (idCoreRules fn) match rule = pat `isPrefixOf` unpackFS (ruleName rule) ruleAppCheck_help :: CompilerPhase -> Id -> [CoreExpr] -> [CoreRule] -> SDoc @@ -545,25 +596,27 @@ ruleAppCheck_help phase fn args rules where n_args = length args i_args = args `zip` [1::Int ..] + rough_args = map roughTopName args check_rule rule = rule_herald rule <> colon <+> rule_info rule - rule_herald (BuiltinRule name _) = - ptext SLIT("Builtin rule") <+> doubleQuotes (ftext name) - rule_herald (Rule name _ _ _ _) = - ptext SLIT("Rule") <+> doubleQuotes (ftext name) + rule_herald (BuiltinRule { ru_name = name }) + = ptext SLIT("Builtin rule") <+> doubleQuotes (ftext name) + rule_herald (Rule { ru_name = name }) + = ptext SLIT("Rule") <+> doubleQuotes (ftext name) rule_info rule - | Just (name,_) <- matchRule noBlackList emptyInScopeSet rule args + | Just _ <- matchRule noBlackList emptyInScopeSet args rough_args rule = text "matches (which is very peculiar!)" - rule_info (BuiltinRule name fn) = text "does not match" + rule_info (BuiltinRule {}) = text "does not match" - rule_info (Rule name act rule_bndrs rule_args _) + rule_info (Rule { ru_name = name, ru_act = act, + ru_bndrs = rule_bndrs, ru_args = rule_args}) | not (isActive phase 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 the rule as a whole does not" + | n_mismatches == 0 = text "all arguments match (considered individually), but rule as a whole does not" | otherwise = text "arguments" <+> ppr mismatches <+> text "do not match (1-indexing)" where n_rule_args = length rule_args @@ -571,61 +624,11 @@ ruleAppCheck_help phase fn args rules mismatches = [i | (rule_arg, (arg,i)) <- rule_args `zip` i_args, not (isJust (match_fn rule_arg arg))] - bndr_set = mkVarSet rule_bndrs - match_fn rule_arg arg = match rule_arg arg bndr_set (\s -> Just ()) emptySubst + lhs_fvs = exprsFreeVars rule_args -- Includes template tyvars + match_fn rule_arg arg = match menv emptySubstEnv rule_arg arg + where + in_scope = lhs_fvs `unionVarSet` exprFreeVars arg + menv = ME { me_env = mkRnEnv2 (mkInScopeSet in_scope) + , me_tmpls = mkVarSet rule_bndrs } \end{code} - -%************************************************************************ -%* * -\subsection{Getting the rules ready} -%* * -%************************************************************************ - -\begin{code} -data RuleBase = RuleBase - IdSet -- Ids with their rules in their specialisations - -- Held as a set, so that it can simply be the initial - -- in-scope set in the simplifier - -- This representation is a bit cute, and I wonder if we should - -- change it to use (IdEnv CoreRule) which seems a bit more natural - -ruleBaseIds (RuleBase ids) = ids -emptyRuleBase = RuleBase emptyVarSet - -extendRuleBaseList :: RuleBase -> [(Id,CoreRule)] -> RuleBase -extendRuleBaseList rule_base new_guys - = foldl extendRuleBase rule_base new_guys - -extendRuleBase :: RuleBase -> (Id,CoreRule) -> RuleBase -extendRuleBase (RuleBase rule_ids) (id, rule) - = RuleBase (extendVarSet rule_ids new_id) - where - new_id = setIdSpecialisation id (addRule id old_rules rule) - old_rules = idSpecialisation (fromMaybe id (lookupVarSet rule_ids id)) - -- Get the old rules from rule_ids if the Id is already there, but - -- if not, use the Id from the incoming rule. If may be a PrimOpId, - -- in which case it may have rules in its belly already. Seems - -- dreadfully hackoid. - -getLocalRules :: Module -> RuleBase -> (IdSet, -- Ids with local rules - RuleBase) -- Non-local rules --- Get the rules for locally-defined Ids out of the RuleBase --- If we miss any rules for Ids defined here, then we end up --- giving the local decl a new Unique (because the in-scope-set is (hackily) the --- same as the non-local-rule-id set, so the Id looks as if it's in scope --- and hence should be cloned), and now the binding for the class method --- doesn't have the same Unique as the one in the Class and the tc-env --- Example: class Foo a where --- op :: a -> a --- {-# RULES "op" op x = x #-} --- --- NB we can't use isLocalId, because isLocalId isn't true of class methods. -getLocalRules this_mod (RuleBase ids) - = (mkVarSet local_ids, RuleBase (mkVarSet imp_ids)) - where - (local_ids, imp_ids) = partition (idIsFrom this_mod) (varSetElems ids) - -pprRuleBase :: RuleBase -> SDoc -pprRuleBase (RuleBase rules) = vcat [ pprTidyIdRules id | id <- varSetElems rules ] -\end{code}