X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Fspecialise%2FRules.lhs;h=8ff1edcac71362b90d7a3cce8052c01984cf4e03;hp=028ec836d109d2248be8bbd530398b9083f21bd5;hb=b3bc4006fef38476d2e66d99879d5adc71d5aa6a;hpb=cf96c6c8f2ead02205e509975282e212a5eb9aee diff --git a/compiler/specialise/Rules.lhs b/compiler/specialise/Rules.lhs index 028ec83..8ff1edc 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, 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 ( exprType ) +import CoreUtils ( exprType, eqExprX ) import PprCore ( pprRules ) -import Type ( Type, TvSubstEnv, tcEqTypeX ) +import Type ( Type, TvSubstEnv ) import TcType ( tcSplitTyConApp_maybe ) import CoreTidy ( tidyRules ) import Id @@ -45,18 +45,82 @@ 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 import Maybes -import OrdList import Bag import Util import Data.List \end{code} +Note [Overall plumbing for rules] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +* After the desugarer: + - The ModGuts initially contains mg_rules :: [CoreRule] of + locally-declared rules for imported Ids. + - Locally-declared rules for locally-declared Ids are attached to + the IdInfo for that Id. See Note [Attach rules to local ids] in + DsBinds + +* TidyPgm strips off all the rules from local Ids and adds them to + mg_rules, so that the ModGuts has *all* the locally-declared rules. + +* The HomePackageTable contains a ModDetails for each home package + module. Each contains md_rules :: [CoreRule] of rules declared in + that module. The HomePackageTable grows as ghc --make does its + up-sweep. In batch mode (ghc -c), the HPT is empty; all imported modules + are treated by the "external" route, discussed next, regardless of + which package they come from. + +* The ExternalPackageState has a single eps_rule_base :: RuleBase for + Ids in other packages. This RuleBase simply grow monotonically, as + ghc --make compiles one module after another. + + During simplification, interface files may get demand-loaded, + as the simplifier explores the unfoldings for Ids it has in + its hand. (Via an unsafePerformIO; the EPS is really a cache.) + That in turn may make the EPS rule-base grow. In contrast, the + HPT never grows in this way. + +* The result of all this is that during Core-to-Core optimisation + there are four sources of rules: + + (a) Rules in the IdInfo of the Id they are a rule for. These are + easy: fast to look up, and if you apply a substitution then + it'll be applied to the IdInfo as a matter of course. + + (b) Rules declared in this module for imported Ids, kept in the + ModGuts. If you do a substitution, you'd better apply the + substitution to these. There are seldom many of these. + + (c) Rules declared in the HomePackageTable. These never change. + + (d) Rules in the ExternalPackageTable. These can grow in response + to lazy demand-loading of interfaces. + +* At the moment (c) is carried in a reader-monad way by the CoreMonad. + The HomePackageTable doesn't have a single RuleBase because technically + we should only be able to "see" rules "below" this module; so we + generate a RuleBase for (c) by combing rules from all the modules + "below" us. That's why we can't just select the home-package RuleBase + from HscEnv. + + [NB: we are inconsistent here. We should do the same for external + pacakges, but we don't. Same for type-class instances.] + +* So in the outer simplifier loop, we combine (b-d) into a single + RuleBase, reading + (b) from the ModGuts, + (c) from the CoreMonad, and + (d) from its mutable variable + [Of coures this means that we won't see new EPS rules that come in + during a single simplifier iteration, but that probably does not + matter.] + + %************************************************************************ %* * \subsection[specialisation-IdInfo]{Specialisation info about an @Id@} @@ -92,15 +156,16 @@ might have a specialisation where pi' :: Lift Int# is the specialised version of pi. \begin{code} -mkLocalRule :: RuleName -> Activation - -> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule +mkRule :: Bool -> 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' -mkLocalRule name act fn bndrs args rhs +mkRule is_auto 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_auto = is_auto, ru_local = is_local } -------------- roughTopNames :: [CoreExpr] -> [Maybe Name] @@ -192,18 +257,32 @@ 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 + %************************************************************************ %* * @@ -242,38 +321,24 @@ pprRuleBase rules = vcat [ pprRules (tidyRules emptyTidyEnv rs) %************************************************************************ %* * -\subsection{Matching} + Matching %* * %************************************************************************ -Note [Extra args in rule matching] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -If we find a matching rule, we return (Just (rule, rhs)), -but the rule firing has only consumed as many of the input args -as the ruleArity says. It's up to the caller to keep track -of any left-over args. E.g. if you call - lookupRule ... f [e1, e2, e3] -and it returns Just (r, rhs), where r has ruleArity 2 -then the real rewrite is - f e1 e2 e3 ==> rhs e3 - -You might think it'd be cleaner for lookupRule to deal with the -leftover arguments, by applying 'rhs' to them, but the main call -in the Simplifier works better as it is. Reason: the 'args' passed -to lookupRule are the result of a lazy substitution - \begin{code} -- | The main rule matching function. Attempts to apply all (active) -- 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 @@ -283,11 +348,14 @@ 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] ) - go ms rs + -- ppr [ (arg_id, unfoldingTemplate unf) + -- | Var arg_id <- args + -- , let unf = idUnfolding arg_id + -- , isCheapUnfolding unf] ) + go ms rs findBest :: (Id, [CoreExpr]) -> (CoreRule,CoreExpr) -> [(CoreRule,CoreExpr)] -> (CoreRule,CoreExpr) @@ -314,20 +382,51 @@ findBest target (rule1,ans1) ((rule2,ans2):prs) (fn,args) = target isMoreSpecific :: CoreRule -> CoreRule -> Bool -isMoreSpecific (BuiltinRule {}) _ = True -isMoreSpecific _ (BuiltinRule {}) = False +-- This tests if one rule is more specific than another +-- We take the view that a BuiltinRule is less specific than +-- anything else, because we want user-define rules to "win" +-- In particular, class ops have a built-in rule, but we +-- any user-specific rules to win +-- eg (Trac #4397) +-- truncate :: (RealFrac a, Integral b) => a -> b +-- {-# RULES "truncate/Double->Int" truncate = double2Int #-} +-- double2Int :: Double -> Int +-- We want the specific RULE to beat the built-in class-op rule +isMoreSpecific (BuiltinRule {}) _ = False +isMoreSpecific (Rule {}) (BuiltinRule {}) = True 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 noBlackList :: Activation -> Bool noBlackList _ = False -- Nothing is black listed +\end{code} + +Note [Extra args in rule matching] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +If we find a matching rule, we return (Just (rule, rhs)), +but the rule firing has only consumed as many of the input args +as the ruleArity says. It's up to the caller to keep track +of any left-over args. E.g. if you call + lookupRule ... f [e1, e2, e3] +and it returns Just (r, rhs), where r has ruleArity 2 +then the real rewrite is + f e1 e2 e3 ==> rhs e3 + +You might think it'd be cleaner for lookupRule to deal with the +leftover arguments, by applying 'rhs' to them, but the main call +in the Simplifier works better as it is. Reason: the 'args' passed +to lookupRule are the result of a lazy substitution -matchRule :: (Activation -> Bool) -> InScopeSet +\begin{code} +------------------------------------ +matchRule :: (Activation -> Bool) -> IdUnfoldingFun + -> InScopeSet -> [CoreExpr] -> [Maybe Name] -> CoreRule -> Maybe CoreExpr @@ -353,43 +452,44 @@ 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 - Nothing -> Nothing - Just (binds, tpl_vals) -> Just (mkLets binds $ - rule_fn `mkApps` tpl_vals) + = case matchN id_unf in_scope tpl_vars tpl_args args of + Nothing -> Nothing + Just (bind_wrapper, tpl_vals) -> Just (bind_wrapper $ + rule_fn `mkApps` tpl_vals) where rule_fn = occurAnalyseExpr (mkLams tpl_vars rhs) -- We could do this when putting things into the rulebase, I guess -\end{code} -\begin{code} --- 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], + -> Maybe (BindWrapper, -- Floated bindings; see Note [Matching lets] [CoreExpr]) +-- 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 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, + ; return (binds, map (lookup_tmpl tv_subst id_subst) tmpl_vars') } where (init_rn_env, tmpl_vars') = mapAccumL rnBndrL (mkRnEnv2 in_scope) tmpl_vars @@ -399,12 +499,12 @@ 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 lookup_tmpl tv_subst id_subst tmpl_var' - | isTyVar tmpl_var' = case lookupVarEnv tv_subst tmpl_var' of + | isTyCoVar 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 @@ -443,15 +543,19 @@ necessary; the renamed ones are the tmpl_vars' -- * The domain of the TvSubstEnv and IdSubstEnv are the template -- variables passed into the match. -- --- * The (OrdList CoreBind) in a SubstEnv are the bindings floated out +-- * The BindWrapper in a SubstEnv are the bindings floated out -- from nested matches; see the Let case of match, below -- -type SubstEnv = (TvSubstEnv, IdSubstEnv, OrdList CoreBind) +type SubstEnv = (TvSubstEnv, IdSubstEnv, BindWrapper) + +type BindWrapper = CoreExpr -> CoreExpr + -- See Notes [Matching lets] and [Matching cases] + -- we represent the floated bindings as a core-to-core function + type IdSubstEnv = IdEnv CoreExpr emptySubstEnv :: SubstEnv -emptySubstEnv = (emptyVarEnv, emptyVarEnv, nilOL) - +emptySubstEnv = (emptyVarEnv, emptyVarEnv, \e -> e) -- At one stage I tried to match even if there are more -- template args than real args. @@ -462,7 +566,8 @@ emptySubstEnv = (emptyVarEnv, emptyVarEnv, nilOL) -- SLPJ July 99 -match :: MatchEnv +match :: IdUnfoldingFun + -> MatchEnv -> SubstEnv -> CoreExpr -- Template -> CoreExpr -- Target @@ -484,52 +589,62 @@ 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 (Note _ e1) e2 = match menv subst e1 e2 -match menv subst e1 (Note _ e2) = match menv subst e1 e2 +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 menv subst e1 (Var v2) -- Note [Expanding variables] - | not (locallyBoundR rn_env v2) -- Note [Do not expand locally-bound variables] - , Just e2' <- expandId v2' - = match (menv { me_env = nukeRnEnvR rn_env }) subst e1 e2' +match id_unfolding_fun menv subst e1 (Var v2) -- Note [Expanding variables] + | not (inRnEnvR rn_env v2) -- Note [Do not expand locally-bound variables] + , Just e2' <- expandUnfolding_maybe (id_unfolding_fun v2') + = match id_unfolding_fun (menv { me_env = nukeRnEnvR rn_env }) subst e1 e2' where 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] -- No need to apply any renaming first (hence no rnOccR) - -- becuase of the not-locallyBoundR - -match 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 (menv { me_env = rn_env' }) - (tv_subst, id_subst, binds `snocOL` bind') - e1 e2' + -- because of the not-inRnEnvR + +match idu menv (tv_subst, id_subst, binds) e1 (Let bind e2) + | okToFloat rn_env bndrs (bindFreeVars bind) -- See Note [Matching lets] + = match idu (menv { me_env = rn_env' }) + (tv_subst, id_subst, binds . Let bind) + e1 e2 where rn_env = me_env menv - bndrs = bindersOf bind - bind_fvs = varSetElems (bindFreeVars bind) - freshly_bound x = not (x `rnInScope` rn_env) - bind' = bind - e2' = e2 - rn_env' = extendRnInScopeList rn_env bndrs + rn_env' = extendRnInScopeList rn_env bndrs + bndrs = bindersOf bind + +{- Disabled: see Note [Matching cases] below +match idu menv (tv_subst, id_subst, binds) e1 + (Case scrut case_bndr ty [(con, alt_bndrs, rhs)]) + | exprOkForSpeculation scrut -- See Note [Matching cases] + , okToFloat rn_env bndrs (exprFreeVars scrut) + = match idu (menv { me_env = rn_env' }) + (tv_subst, id_subst, binds . case_wrap) + e1 rhs + where + rn_env = me_env menv + rn_env' = extendRnInScopeList rn_env bndrs + bndrs = case_bndr : alt_bndrs + case_wrap rhs' = Case scrut case_bndr ty [(con, alt_bndrs, rhs')] +-} -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 } @@ -538,45 +653,55 @@ 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 + (rn_env', new_x) = rnEtaL (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 + (rn_env', new_x) = rnEtaR (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 } + ; 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 +okToFloat :: RnEnv2 -> [Var] -> VarSet -> Bool +okToFloat rn_env bndrs bind_fvs + = all freshly_bound bndrs + && foldVarSet ((&&) . not_captured) True bind_fvs + where + freshly_bound x = not (x `rnInScope` rn_env) + not_captured fv = not (inRnEnvR rn_env fv) + +------------------------------------------ +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)) @@ -599,7 +724,7 @@ 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' | eqExpr (nukeRnEnvL rn_env) e1' e2 + Just e1' | eqExprX idu (nukeRnEnvL rn_env) e1' e2 -> Just subst | otherwise @@ -620,38 +745,37 @@ 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} -Matching Core types: use the matcher in TcType. -Notice that we treat newtypes as opaque. For example, suppose -we have a specialised version of a function at a newtype, say - newtype T = MkT Int -We only want to replace (f T) with f', not (f Int). - -\begin{code} ------------------------------------------ match_ty :: MatchEnv -> SubstEnv -> Type -- Template -> Type -- Target -> Maybe SubstEnv +-- Matching Core types: use the matcher in TcType. +-- Notice that we treat newtypes as opaque. For example, suppose +-- we have a specialised version of a function at a newtype, say +-- newtype T = MkT Int +-- We only want to replace (f T) with f', not (f Int). + match_ty menv (tv_subst, id_subst, binds) ty1 ty2 = do { tv_subst' <- Unify.ruleMatchTyX menv tv_subst ty1 ty2 ; return (tv_subst', id_subst, binds) } @@ -704,13 +828,13 @@ 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. + (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 @@ -736,7 +860,25 @@ Other cases to think about (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 [Matching cases] +~~~~~~~~~~~~~~~~~~~~~ +{- NOTE: This idea is currently disabled. It really only works if + the primops involved are OkForSpeculation, and, since + they have side effects readIntOfAddr and touch are not. + Maybe we'll get back to this later . -} + +Consider + f (case readIntOffAddr# p# i# realWorld# of { (# s#, n# #) -> + case touch# fp s# of { _ -> + I# n# } } ) +This happened in a tight loop generated by stream fusion that +Roman encountered. We'd like to treat this just like the let +case, because the primops concerned are ok-for-speculation. +That is, we'd like to behave as if it had been + case readIntOffAddr# p# i# realWorld# of { (# s#, n# #) -> + case touch# fp s# of { _ -> + f (I# n# } } ) + Note [Lookup in-scope] ~~~~~~~~~~~~~~~~~~~~~~ Consider this example @@ -772,82 +914,6 @@ at all. That is why the 'lookupRnInScope' call in the (Var v2) case of 'match' is so important. -\begin{code} -eqExpr :: 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 env (Var v1) e2 - | not (locallyBoundL env v1) - , Just e1' <- expandId (lookupRnInScope env v1) - = eqExpr (nukeRnEnvL env) e1' e2 - -eqExpr env e1 (Var v2) - | not (locallyBoundR env v2) - , Just e2' <- expandId (lookupRnInScope env v2) - = eqExpr (nukeRnEnvR env) e1 e2' - -eqExpr _ (Lit lit1) (Lit lit2) = lit1 == lit2 -eqExpr env (App f1 a1) (App f2 a2) = eqExpr env f1 f2 && eqExpr env a1 a2 -eqExpr env (Lam v1 e1) (Lam v2 e2) = eqExpr (rnBndr2 env v1 v2) e1 e2 -eqExpr env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && eqExpr env e1 e2 -eqExpr env (Cast e1 co1) (Cast e2 co2) = tcEqTypeX env co1 co2 && eqExpr env e1 e2 -eqExpr env (Type t1) (Type t2) = tcEqTypeX env t1 t2 - -eqExpr env (Let (NonRec v1 r1) e1) - (Let (NonRec v2 r2) e2) = eqExpr env r1 r2 - && eqExpr (rnBndr2 env v1 v2) e1 e2 -eqExpr env (Let (Rec ps1) e1) - (Let (Rec ps2) e2) = equalLength ps1 ps2 - && and (zipWith eq_rhs ps1 ps2) - && eqExpr 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 env' r1 r2 -eqExpr env (Case e1 v1 t1 a1) - (Case e2 v2 t2 a2) = eqExpr env e1 e2 - && tcEqTypeX env t1 t2 - && equalLength a1 a2 - && and (zipWith (eq_alt env') a1 a2) - where - env' = rnBndr2 env v1 v2 - -eqExpr _ _ _ = False - -eq_alt :: RnEnv2 -> CoreAlt -> CoreAlt -> Bool -eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 && eqExpr (rnBndrs2 env vs1 vs2) r1 r2 - -eq_note :: RnEnv2 -> Note -> Note -> Bool -eq_note _ (SCC cc1) (SCC cc2) = cc1 == cc2 -eq_note _ (CoreNote s1) (CoreNote s2) = s1 == s2 -eq_note _ (InlineMe) (InlineMe) = True -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 - - -expandId :: Id -> Maybe CoreExpr -expandId id - | isExpandableUnfolding unfolding = Just (unfoldingTemplate unfolding) - | otherwise = Nothing - where - unfolding = idUnfolding id -\end{code} - %************************************************************************ %* * Rule-check the program @@ -860,12 +926,12 @@ expandId id \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 @@ -874,11 +940,17 @@ 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 } @@ -913,13 +985,13 @@ 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)] @@ -936,14 +1008,14 @@ 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" @@ -955,7 +1027,7 @@ 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)