\begin{code}
module Rules (
- RuleBase, emptyRuleBase, extendRuleBase, extendRuleBaseList,
- prepareLocalRuleBase, prepareOrphanRuleBase,
- unionRuleBase, lookupRule, addRule, addIdSpecialisations,
- ProtoCoreRule(..), pprProtoCoreRule, pprRuleBase,
- localRule, orphanRule
+ RuleBase, emptyRuleBase,
+ extendRuleBaseList,
+ ruleBaseIds, pprRuleBase, ruleCheckProgram,
+
+ lookupRule, addRule, addRules, addIdSpecialisations
) where
#include "HsVersions.h"
import CoreSyn -- All of it
import OccurAnal ( occurAnalyseRule )
-import CoreFVs ( exprFreeVars, idRuleVars, ruleRhsFreeVars, ruleSomeLhsFreeVars )
+import CoreFVs ( exprFreeVars, exprsFreeVars, ruleRhsFreeVars )
import CoreUnfold ( isCheapUnfolding, unfoldingTemplate )
-import CoreUtils ( eqExpr )
-import PprCore ( pprCoreRule )
-import Subst ( Subst, InScopeSet, mkInScopeSet, lookupSubst, extendSubst,
- substEnv, setSubstEnv, emptySubst, isInScope,
- bindSubstList, unBindSubstList, substInScope, uniqAway
- )
-import Id ( Id, idUnfolding, zapLamIdInfo,
- idSpecialisation, setIdSpecialisation,
- setIdNoDiscard
- )
-import Name ( isLocallyDefined )
-import Var ( isTyVar, isId )
+import CoreUtils ( tcEqExprX )
+import Type ( Type )
+import CoreTidy ( pprTidyIdRules )
+import Id ( Id, idUnfolding, isLocalId, idSpecialisation, setIdSpecialisation )
+import Var ( Var )
import VarSet
import VarEnv
-import Type ( mkTyVarTy )
-import qualified Unify ( match )
+import Unify ( tcMatchTyX, MatchEnv(..) )
+import BasicTypes ( Activation, CompilerPhase, isActive )
-import UniqFM
import Outputable
-import Maybes ( maybeToBool )
-import Util ( sortLt )
+import FastString
+import Maybe ( isJust, fromMaybe )
+import Bag
+import List ( isPrefixOf )
\end{code}
%************************************************************************
\begin{code}
-matchRules :: InScopeSet -> [CoreRule] -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
+matchRules :: (Activation -> Bool) -> InScopeSet
+ -> [CoreRule] -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
-- See comments on matchRule
-matchRules in_scope [] args = Nothing
-matchRules in_scope (rule:rules) args
- = case matchRule in_scope rule args of
+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 in_scope rules args
+ Nothing -> matchRules is_active in_scope rules args
+noBlackList :: Activation -> Bool
+noBlackList act = False -- Nothing is black listed
-matchRule :: InScopeSet -> CoreRule -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
+matchRule :: (Activation -> Bool) -> InScopeSet
+ -> CoreRule -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
-- If (matchRule rule args) returns Just (name,rhs)
-- then (f args) matches the rule, and the corresponding
--
-- 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 in_scope rule@(BuiltinRule match_fn) args = match_fn args
-
-matchRule in_scope rule@(Rule rn tpl_vars tpl_args rhs) args
- = 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 -> maybeToBool (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
+
+matchRule is_active in_scope rule@(BuiltinRule name match_fn) args
+ = case match_fn args of
+ Just expr -> Just (name,expr)
+ Nothing -> Nothing
+
+matchRule is_active in_scope rule@(Rule rn act tpl_vars tpl_args rhs) args
+ | not (is_active act)
+ = Nothing
+ | otherwise
+ = case matchN in_scope tpl_vars tpl_args args of
+ Just (tpl_vals, leftovers) -> Just (rn, mkLams tpl_vars rhs `mkApps` tpl_vals `mkApps` leftovers)
+ Nothing -> Nothing
\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.
- | eqExpr (Var v1) e2 -> kont subst
- -- v1 is not a template variable, so it must be a global constant
+-- 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
- Just (DoneEx e2') | eqExpr e2' e2 -> kont subst
- other -> match_fail
+match :: MatchEnv
+ -> SubstEnv
+ -> CoreExpr -- Template
+ -> CoreExpr -- Target
+ -> Maybe SubstEnv
+
+-- See the notes with Unify.match, which matches types
+-- Everything is very similar for terms
-match (Lit lit1) (Lit lit2) tpl_vars 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
+
+-- 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 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
-
+ 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
--- We can't cope with lets in the template
+------------------------------------------
+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
+ = do { subst1 <- match menv' subst r1 r2
+ ; match_alts menv subst1 alts1 alts2 }
+ where
+ menv' :: MatchEnv
+ menv' = menv { me_env = rnBndrs2 (me_env menv) vs1 vs2 }
-match e1 e2 tpl_vars kont subst = match_fail
+match_alts menv subst alts1 alts2
+ = 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_alts [] [] tpl_vars kont subst
- = kont subst
-match_alts ((c1,vs1,r1):alts1) ((c2,vs2,r2):alts2) tpl_vars kont subst
- | 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'
- 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 = not (maybeToBool (lookupSubst subst v))
- bug_msg = sep [ppr vs1, ppr vs2]
-
-----------------------------------------
-match_ty ty1 ty2 tpl_vars kont subst
- = case Unify.match ty1 ty2 tpl_vars Just (substEnv subst) of
- Nothing -> match_fail
- Just senv' -> kont (setSubstEnv subst senv')
-
-----------------------------------------
-matches [] [] tpl_vars kont subst
- = kont subst
-matches (e:es) (e':es') tpl_vars kont subst
- = match e e' tpl_vars (matches es es' tpl_vars kont) subst
-matches es es' tpl_vars kont subst
- = match_fail
-
-----------------------------------------
-mkVarArg :: CoreBndr -> CoreArg
-mkVarArg v | isId v = Var v
- | otherwise = Type (mkTyVarTy v)
+match_ty menv (tv_subst, id_subst) ty1 ty2
+ = do { tv_subst' <- Unify.tcMatchTyX menv tv_subst ty1 ty2
+ ; return (tv_subst', id_subst) }
\end{code}
+
%************************************************************************
%* *
\subsection{Adding a new rule}
%************************************************************************
\begin{code}
-addRule :: CoreRules -> Id -> CoreRule -> CoreRules
+addRules :: Id -> CoreRules -> [CoreRule] -> CoreRules
+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.
-- We make no check for rules that unify without one dominating
-- the other. Arguably this would be a bug.
-addRule (Rules rules rhs_fvs) id rule@(BuiltinRule _)
+addRules id rules rule_list = foldl (addRule id) rules rule_list
+
+addRule id (Rules rules rhs_fvs) rule@(BuiltinRule _ _)
= Rules (rule:rules) rhs_fvs
-- Put it at the start for lack of anything better
-addRule (Rules rules rhs_fvs) id rule
+addRule id (Rules rules rhs_fvs) rule
= Rules (insertRule rules new_rule) (rhs_fvs `unionVarSet` new_rhs_fvs)
where
new_rule = occurAnalyseRule rule
-- 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 _)
+insertRule rules new_rule@(Rule _ _ tpl_vars tpl_args _)
= go rules
where
tpl_var_set = mkInScopeSet (mkVarSet tpl_vars)
go (rule:rules) | new_is_more_specific rule = (new_rule:rule:rules)
| otherwise = rule : go rules
- new_is_more_specific rule = maybeToBool (matchRule tpl_var_set rule tpl_args)
+ new_is_more_specific rule = isJust (matchRule noBlackList tpl_var_set rule tpl_args)
-addIdSpecialisations :: Id -> [([CoreBndr], [CoreExpr], CoreExpr)] -> Id
-addIdSpecialisations id spec_stuff
- = setIdSpecialisation id new_rules
+addIdSpecialisations :: Id -> [CoreRule] -> Id
+addIdSpecialisations id rules
+ = setIdSpecialisation id new_specs
where
- rule_name = _PK_ ("SPEC " ++ showSDoc (ppr id))
- new_rules = foldr add (idSpecialisation id) spec_stuff
- add (vars, args, rhs) rules = addRule rules id (Rule rule_name vars args rhs)
+ new_specs = addRules id (idSpecialisation id) rules
\end{code}
%************************************************************************
%* *
-\subsection{Preparing the rule base
+\subsection{Looking up a rule}
%* *
%************************************************************************
\begin{code}
-data ProtoCoreRule
- = ProtoCoreRule
- Bool -- True <=> this rule was defined in this module,
- Id -- What Id is it for
- CoreRule -- The rule itself
-
-
-pprProtoCoreRule (ProtoCoreRule _ fn rule) = pprCoreRule (ppr fn) rule
-
-lookupRule :: InScopeSet -> Id -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
-lookupRule in_scope fn args
- = case idSpecialisation fn of
- Rules rules _ -> matchRules in_scope rules args
-
-localRule :: ProtoCoreRule -> Bool
-localRule (ProtoCoreRule local _ _) = local
-
-orphanRule :: ProtoCoreRule -> Bool
--- An "orphan rule" is one that is defined in this
--- module, but for an *imported* function. We need
--- to track these separately when generating the interface file
-orphanRule (ProtoCoreRule local fn _)
- = local && not (isLocallyDefined fn)
+lookupRule :: (Activation -> Bool)
+ -> InScopeSet
+ -> RuleBase -- Ids from other modules
+ -> Id -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
+lookupRule is_active in_scope rules fn args
+ = case idSpecialisation fn' of
+ Rules rules _ -> matchRules is_active in_scope rules args
+ where
+ fn' | isLocalId fn = fn
+ | Just ext_fn <- lookupVarSet (ruleBaseIds rules) fn = ext_fn
+ | otherwise = fn
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Checking a program for failing rule applications}
+%* *
+%************************************************************************
+
+-----------------------------------------------------
+ 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.
+
+NB: we assume that this follows a run of the simplifier, so every Id
+occurrence (including occurrences of imported Ids) is decorated with
+all its (active) rules. No need to construct a rule base or anything
+like that.
+
+\begin{code}
+ruleCheckProgram :: CompilerPhase -> String -> [CoreBind] -> SDoc
+-- Report partial matches for rules beginning
+-- with the specified string
+ruleCheckProgram phase rule_pat binds
+ | isEmptyBag results
+ = text "Rule check results: no rule application sites"
+ | otherwise
+ = vcat [text "Rule check results:",
+ line,
+ vcat [ p $$ line | p <- bagToList results ]
+ ]
+ where
+ results = unionManyBags (map (ruleCheckBind (phase, rule_pat)) binds)
+ line = text (replicate 20 '-')
+
+type RuleCheckEnv = (CompilerPhase, String) -- Phase and Pattern
+
+ruleCheckBind :: RuleCheckEnv -> CoreBind -> Bag SDoc
+ -- The Bag returned has one SDoc for each call site found
+ruleCheckBind env (NonRec b r) = ruleCheck env r
+ruleCheckBind env (Rec prs) = unionManyBags [ruleCheck env r | (b,r) <- prs]
+
+ruleCheck :: RuleCheckEnv -> CoreExpr -> Bag SDoc
+ruleCheck env (Var v) = emptyBag
+ruleCheck env (Lit l) = emptyBag
+ruleCheck env (Type ty) = emptyBag
+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]
+
+ruleCheckApp env (App f a) as = ruleCheck env a `unionBags` ruleCheckApp env f (a:as)
+ruleCheckApp env (Var f) as = ruleCheckFun env f as
+ruleCheckApp env other as = ruleCheck env other
+\end{code}
+
+\begin{code}
+ruleCheckFun :: RuleCheckEnv -> Id -> [CoreExpr] -> Bag SDoc
+-- Produce a report for all rules matching the predicate
+-- saying why it doesn't match the specified application
+
+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
+ match rule = pat `isPrefixOf` unpackFS (ruleName rule)
+
+ruleAppCheck_help :: CompilerPhase -> Id -> [CoreExpr] -> [CoreRule] -> SDoc
+ruleAppCheck_help phase 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)]
+ where
+ n_args = length args
+ i_args = args `zip` [1::Int ..]
+
+ 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_info rule
+ | Just (name,_) <- matchRule noBlackList emptyInScopeSet rule args
+ = text "matches (which is very peculiar!)"
+
+ rule_info (BuiltinRule name fn) = text "does not match"
+
+ rule_info (Rule name act rule_bndrs 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 rule as a whole does not"
+ | otherwise = text "arguments" <+> ppr mismatches <+> text "do not match (1-indexing)"
+ where
+ n_rule_args = length rule_args
+ n_mismatches = length mismatches
+ mismatches = [i | (rule_arg, (arg,i)) <- rule_args `zip` i_args,
+ 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
+ where
+ in_scope = lhs_fvs `unionVarSet` exprFreeVars arg
+ menv = ME { me_env = mkRnEnv2 (mkInScopeSet in_scope)
+ , me_tmpls = mkVarSet rule_bndrs }
\end{code}
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
- IdSet -- Ids (whether local or imported) mentioned on
- -- LHS of some rule; these should be black listed
+ruleBaseIds (RuleBase ids) = ids
+emptyRuleBase = RuleBase emptyVarSet
-emptyRuleBase = RuleBase emptyVarSet emptyVarSet
-
-extendRuleBaseList :: RuleBase -> [(Id,CoreRule)] -> RuleBase
+extendRuleBaseList :: RuleBase -> [IdCoreRule] -> RuleBase
extendRuleBaseList rule_base new_guys
= foldl extendRuleBase rule_base new_guys
-extendRuleBase :: RuleBase -> (Id,CoreRule) -> RuleBase
-extendRuleBase (RuleBase rule_ids rule_fvs) (id, rule)
+extendRuleBase :: RuleBase -> IdCoreRule -> RuleBase
+extendRuleBase (RuleBase rule_ids) (IdCoreRule id _ rule)
= RuleBase (extendVarSet rule_ids new_id)
- (rule_fvs `unionVarSet` extendVarSet lhs_fvs id)
- where
- new_id = setIdSpecialisation id (addRule old_rules id rule)
- old_rules = case lookupVarSet rule_ids id of
- Nothing -> emptyCoreRules
- Just id' -> idSpecialisation id'
-
- lhs_fvs = ruleSomeLhsFreeVars isId rule
- -- Find *all* the free Ids of the LHS, not just
- -- locally defined ones!!
-
-unionRuleBase (RuleBase rule_ids1 black_ids1) (RuleBase rule_ids2 black_ids2)
- = RuleBase (plusUFM_C merge_rules rule_ids1 rule_ids2)
- (unionVarSet black_ids1 black_ids2)
where
-
-merge_rules id1 id2 = let rules1 = idSpecialisation id1
- rules2 = idSpecialisation id2
- new_rules = foldl (addRule id1) rules1 (rulesRules rules2)
- in
- setIdSpecialisation id1 new_rules
+ 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.
pprRuleBase :: RuleBase -> SDoc
-pprRuleBase (RuleBase rules _) = vcat [ pprCoreRule (ppr id) rs
- | id <- varSetElems rules,
- rs <- rulesRules $ idSpecialisation id ]
-
--- prepareLocalRuleBase takes the CoreBinds and rules defined in this module.
--- It attaches those rules that are for local Ids to their binders, and
--- returns the remainder attached to Ids in an IdSet. It also returns
--- Ids mentioned on LHS of some rule; these should be blacklisted.
-
--- The rule Ids and LHS Ids are black-listed; that is, they aren't inlined
--- so that the opportunity to apply the rule isn't lost too soon
-
-prepareLocalRuleBase :: [CoreBind] -> [(Id,CoreRule)] -> ([CoreBind], RuleBase)
-prepareLocalRuleBase binds local_rules
- = error "urk"
-{-
- = (map zap_bind binds, RuleBase imported_id_rule_ids rule_lhs_fvs)
- where
- RuleBase rule_ids rule_lhs_fvs = extendRuleBaseList emptyRuleBase local_rules
- imported_id_rule_ids = filterVarSet (not . isLocallyDefined) rule_ids
-
- -- rule_fvs is the set of all variables mentioned in this module's rules
- rule_fvs = foldVarSet (unionVarSet . idRuleVars) rule_lhs_fvs rule_ids
-
- -- Attach the rules for each locally-defined Id to that Id.
- -- - This makes the rules easier to look up
- -- - It means that transformation rules and specialisations for
- -- locally defined Ids are handled uniformly
- -- - It keeps alive things that are referred to only from a rule
- -- (the occurrence analyser knows about rules attached to Ids)
- -- - It makes sure that, when we apply a rule, the free vars
- -- of the RHS are more likely to be in scope
- --
- -- The LHS and RHS Ids are marked 'no-discard'.
- -- This means that the binding won't be discarded EVEN if the binding
- -- ends up being trivial (v = w) -- the simplifier would usually just
- -- substitute w for v throughout, but we don't apply the substitution to
- -- the rules (maybe we should?), so this substitution would make the rule
- -- bogus.
- zap_bind (NonRec b r) = NonRec (zap_bndr b) r
- zap_bind (Rec prs) = Rec [(zap_bndr b, r) | (b,r) <- prs]
-
- zap_bndr bndr = case lookupVarSet rule_ids bndr of
- Just bndr' -> setIdNoDiscard bndr'
- Nothing | bndr `elemVarSet` rule_fvs -> setIdNoDiscard bndr
- | otherwise -> bndr
--}
-
-addRuleToId id rule = setIdSpecialisation id (addRule (idSpecialisation id) id rule)
-
--- prepareOrphanRuleBase does exactly the same as prepareLocalRuleBase, except that
--- it assumes that none of the rules can be attached to local Ids.
-
-prepareOrphanRuleBase :: [ProtoCoreRule] -> RuleBase
-prepareOrphanRuleBase imported_rules
- = error "urk"
-{-
- = foldr add_rule emptyRuleBase imported_rules
--}
+pprRuleBase (RuleBase rules) = vcat [ pprTidyIdRules id | id <- varSetElems rules ]
\end{code}
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