%
% (c) The GRASP/AQUA Project, Glasgow University, 19921998
%
\section[CoreRules]{Transformation rules}
\begin{code}
module Rules (
RuleBase,
emptyRuleBase, mkRuleBase, extendRuleBaseList,
unionRuleBase, pprRuleBase,
ruleCheckProgram,
mkSpecInfo, extendSpecInfo, addSpecInfo,
addIdSpecialisations,
rulesOfBinds, getRules, pprRulesForUser,
lookupRule, mkLocalRule, roughTopNames
) where
#include "HsVersions.h"
import CoreSyn
import OccurAnal ( occurAnalyseExpr )
import CoreFVs ( exprFreeVars, exprsFreeVars, bindFreeVars, rulesFreeVars )
import CoreUtils ( exprType )
import PprCore ( pprRules )
import Type ( Type, TvSubstEnv, tcEqTypeX )
import TcType ( tcSplitTyConApp_maybe )
import CoreTidy ( tidyRules )
import Id
import IdInfo ( SpecInfo( SpecInfo ) )
import Var ( Var )
import VarEnv
import VarSet
import Name ( Name, NamedThing(..) )
import NameEnv
import Unify ( ruleMatchTyX, MatchEnv(..) )
import BasicTypes ( Activation )
import StaticFlags ( opt_PprStyle_Debug )
import Outputable
import FastString
import Maybes
import OrdList
import Bag
import Util
import Data.List
\end{code}
%************************************************************************
%* *
\subsection[specialisationIdInfo]{Specialisation info about an @Id@}
%* *
%************************************************************************
A @CoreRule@ holds details of one rule for an @Id@, which
includes its specialisations.
For example, if a rule for @f@ contains the mapping:
\begin{verbatim}
forall a b d. [Type (List a), Type b, Var d] ===> f' a b
\end{verbatim}
then when we find an application of f to matching types, we simply replace
it by the matching RHS:
\begin{verbatim}
f (List Int) Bool dict ===> f' Int Bool
\end{verbatim}
All the stuff about how many dictionaries to discard, and what types
to apply the specialised function to, are handled by the fact that the
Rule contains a template for the result of the specialisation.
There is one more exciting case, which is dealt with in exactly the same
way. If the specialised value is unboxed then it is lifted at its
definition site and unlifted at its uses. For example:
pi :: forall a. Num a => a
might have a specialisation
[Int#] ===> (case pi' of Lift pi# -> pi#)
where pi' :: Lift Int# is the specialised version of pi.
\begin{code}
mkLocalRule :: RuleName -> Activation
-> Name -> [CoreBndr] -> [CoreExpr] -> CoreExpr -> CoreRule
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_local = True }
roughTopNames :: [CoreExpr] -> [Maybe Name]
roughTopNames args = map roughTopName args
roughTopName :: CoreExpr -> Maybe Name
roughTopName (Type ty) = case tcSplitTyConApp_maybe ty of
Just (tc,_) -> Just (getName tc)
Nothing -> Nothing
roughTopName (App f _) = roughTopName f
roughTopName (Var f) | isGlobalId f = Just (idName f)
| otherwise = Nothing
roughTopName _ = Nothing
ruleCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool
ruleCantMatch (Just n1 : ts) (Just n2 : as) = n1 /= n2 || ruleCantMatch ts as
ruleCantMatch (_ : ts) (_ : as) = ruleCantMatch ts as
ruleCantMatch _ _ = False
\end{code}
\begin{code}
pprRulesForUser :: [CoreRule] -> SDoc
pprRulesForUser rules
= withPprStyle defaultUserStyle $
pprRules $
sortLe le_rule $
tidyRules emptyTidyEnv rules
where
le_rule r1 r2 = ru_name r1 <= ru_name r2
\end{code}
%************************************************************************
%* *
SpecInfo: the rules in an IdInfo
%* *
%************************************************************************
\begin{code}
mkSpecInfo :: [CoreRule] -> SpecInfo
mkSpecInfo rules = SpecInfo rules (rulesFreeVars rules)
extendSpecInfo :: SpecInfo -> [CoreRule] -> SpecInfo
extendSpecInfo (SpecInfo rs1 fvs1) rs2
= SpecInfo (rs2 ++ rs1) (rulesFreeVars 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 []
= id
addIdSpecialisations id rules
= setIdSpecialisation id $
extendSpecInfo (idSpecialisation id) rules
rulesOfBinds :: [CoreBind] -> [CoreRule]
rulesOfBinds binds = concatMap (concatMap idCoreRules . bindersOf) binds
getRules :: RuleBase -> Id -> [CoreRule]
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` [])
\end{code}
%************************************************************************
%* *
RuleBase
%* *
%************************************************************************
\begin{code}
type RuleBase = NameEnv [CoreRule]
emptyRuleBase :: RuleBase
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}
%************************************************************************
%* *
\subsection{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 leftover 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}
lookupRule :: (Activation -> Bool) -> InScopeSet
-> Id -> [CoreExpr]
-> [CoreRule] -> Maybe (CoreRule, CoreExpr)
lookupRule is_active in_scope fn args rules
=
case go [] rules of
[] -> Nothing
(m:ms) -> Just (findBest (fn,args) m ms)
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)
findBest _ (rule,ans) [] = (rule,ans)
findBest target (rule1,ans1) ((rule2,ans2):prs)
| rule1 `isMoreSpecific` rule2 = findBest target (rule1,ans1) prs
| rule2 `isMoreSpecific` rule1 = findBest target (rule2,ans2) prs
| debugIsOn = let pp_rule rule
| opt_PprStyle_Debug = ppr rule
| otherwise = doubleQuotes (ftext (ru_name rule))
in pprTrace "Rules.findBest: rule overlap (Rule 1 wins)"
(vcat [if opt_PprStyle_Debug then
ptext (sLit "Expression to match:") <+> ppr fn <+> sep (map ppr args)
else empty,
ptext (sLit "Rule 1:") <+> pp_rule rule1,
ptext (sLit "Rule 2:") <+> pp_rule rule2]) $
findBest target (rule1,ans1) prs
| otherwise = findBest target (rule1,ans1) prs
where
(fn,args) = target
isMoreSpecific :: CoreRule -> CoreRule -> Bool
isMoreSpecific (BuiltinRule {}) _ = True
isMoreSpecific _ (BuiltinRule {}) = False
isMoreSpecific (Rule { ru_bndrs = bndrs1, ru_args = args1 })
(Rule { ru_bndrs = bndrs2, ru_args = args2 })
= isJust (matchN in_scope bndrs2 args2 args1)
where
in_scope = mkInScopeSet (mkVarSet bndrs1)
noBlackList :: Activation -> Bool
noBlackList _ = False
matchRule :: (Activation -> Bool) -> InScopeSet
-> [CoreExpr] -> [Maybe Name]
-> CoreRule -> Maybe CoreExpr
matchRule _is_active _in_scope args _rough_args
(BuiltinRule { ru_try = match_fn })
= case match_fn args of
Just expr -> Just expr
Nothing -> Nothing
matchRule is_active 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)
where
rule_fn = occurAnalyseExpr (mkLams tpl_vars rhs)
\end{code}
\begin{code}
matchN :: InScopeSet
-> [Var]
-> [CoreExpr]
-> [CoreExpr]
-> Maybe ([CoreBind],
[CoreExpr])
matchN 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,
map (lookup_tmpl tv_subst id_subst) tmpl_vars') }
where
(init_rn_env, tmpl_vars') = mapAccumL rnBndrL (mkRnEnv2 in_scope) tmpl_vars
init_menv = ME { me_tmpls = mkVarSet tmpl_vars', me_env = init_rn_env }
go _ subst [] _ = Just subst
go _ _ _ [] = Nothing
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
_ -> unbound tmpl_var'
unbound var = pprPanic "Template variable unbound in rewrite rule"
(ppr var $$ ppr tmpl_vars $$ ppr tmpl_vars' $$ ppr tmpl_es $$ ppr target_es)
\end{code}
Note [Template binders]
~~~~~~~~~~~~~~~~~~~~~~~
Consider the following match:
Template: forall x. f x
Target: f (x+1)
This should succeed, because the template variable 'x' has
nothing to do with the 'x' in the target.
On reflection, this case probably does just work, but this might not
Template: forall x. f (\x.x)
Target: f (\y.y)
Here we want to clone when we find the \x, but to know that x must be in scope
To achive this, we use rnBndrL to rename the template variables if
necessary; the renamed ones are the tmpl_vars'
The inner workings of matching
\begin{code}
type SubstEnv = (TvSubstEnv, IdSubstEnv, OrdList CoreBind)
type IdSubstEnv = IdEnv CoreExpr
emptySubstEnv :: SubstEnv
emptySubstEnv = (emptyVarEnv, emptyVarEnv, nilOL)
match :: MatchEnv
-> SubstEnv
-> CoreExpr
-> CoreExpr
-> Maybe SubstEnv
match menv subst (Var v1) e2
| Just subst <- match_var 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 menv subst e1 (Var v2)
| not (locallyBoundR rn_env v2)
, Just e2' <- expandId v2'
= match (menv { me_env = nukeRnEnvR rn_env }) subst e1 e2'
where
v2' = lookupRnInScope rn_env v2
rn_env = me_env menv
match menv (tv_subst, id_subst, binds) e1 (Let bind e2)
| all freshly_bound bndrs
, not (any (locallyBoundR rn_env) bind_fvs)
= match (menv { me_env = rn_env' })
(tv_subst, id_subst, binds `snocOL` bind')
e1 e2'
where
rn_env = me_env menv
bndrs = bindersOf bind
bind_fvs = varSetElems (bindFreeVars bind)
freshly_bound x = not (x `rnInScope` rn_env)
bind' = bind
e2' = e2
rn_env' = extendRnInScopeList rn_env bndrs
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 menv subst (Lam x1 e1) (Lam x2 e2)
= match menv' subst e1 e2
where
menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 }
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' }
match menv subst e1 (Lam x2 e2)
= match menv' subst (App e1 (varToCoreExpr new_x)) e2
where
(rn_env', new_x) = rnBndrR (me_env menv) x2
menv' = menv { me_env = rn_env' }
match menv subst (Case e1 x1 ty1 alts1) (Case e2 x2 ty2 alts2)
= do { subst1 <- match_ty menv subst ty1 ty2
; subst2 <- match menv subst1 e1 e2
; let menv' = menv { me_env = rnBndr2 (me_env menv) x1 x2 }
; match_alts menv' subst2 alts1 alts2
}
match menv subst (Type ty1) (Type ty2)
= match_ty menv subst ty1 ty2
match menv subst (Cast e1 co1) (Cast e2 co2)
= do { subst1 <- match_ty menv subst co1 co2
; match menv subst1 e1 e2 }
match _ _ _e1 _e2 =
Nothing
match_var :: MatchEnv
-> SubstEnv
-> Var
-> CoreExpr
-> Maybe SubstEnv
match_var 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))
-> Nothing
| otherwise
-> do { tv_subst' <- Unify.ruleMatchTyX menv tv_subst (idType v1') (exprType e2)
; return (tv_subst', extendVarEnv id_subst v1' e2, binds) }
Just e1' | eqExpr (nukeRnEnvL rn_env) e1' e2
-> Just subst
| otherwise
-> Nothing
| otherwise
= case e2 of
Var v2 | v1' == rnOccR rn_env v2 -> Just subst
_ -> Nothing
where
rn_env = me_env menv
v1' = rnOccL rn_env v1
match_alts :: MatchEnv
-> SubstEnv
-> [CoreAlt]
-> [CoreAlt]
-> Maybe SubstEnv
match_alts _ 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_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
-> Type
-> Maybe SubstEnv
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) }
\end{code}
Note [Expanding variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~
Here is another Very Important rule: if the term being matched is a
variable, we expand it so long as its unfolding is "expandable". (Its
occurrence information is not necessarily up to date, so we don't use
it.) By "expandable" we mean a WHNF or a "constructor-like" application.
This is the key reason for "constructor-like" Ids. If we have
then in the term
let v = g 3 in ....(f v)....
we want to make the rule fire, to replace (f v) with (h 3).
Note [Do not expand locallybound variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Do *not* expand locallybound variables, else there's a worry that the
unfolding might mention variables that are themselves renamed.
Example
case x of y { (p,q) -> ...y... }
Don't expand 'y' to (p,q) because p,q might themselves have been
renamed. Essentially we only expand unfoldings that are "outside"
the entire match.
Hence, (a) the guard (not (isLocallyBoundR v2))
(b) when we expand we nuke the renaming envt (nukeRnEnvR).
Note [Notes in RULE matching]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Look through Notes in both template and expression being matched. In
particular, we don't want to be confused by InlineMe notes. Maybe we
should be more careful about profiling notes, but for now I'm just
riding roughshod over them. cf Note [Notes in call patterns] in
SpecConstr
Note [Matching lets]
~~~~~~~~~~~~~~~~~~~~
Matching a letexpression. Consider
RULE forall x. f (g x) = <rhs>
and target expression
f (let { w=R } in g E))
Then we'd like the rule to match, to generate
let { w=R } in (\x. <rhs>) E
In effect, we want to float the letbinding outward, to enable
the match to happen. This is the WHOLE REASON for accumulating
bindings in the SubstEnv
We can only do this if
(a) Widening the scope of w does not capture any variables
We use a conservative test: w is not already in scope
If not, we clone the binders, and substitute
(b) The free variables of R are not bound by the part of the
target expression outside the let binding; e.g.
f (\v. let w = v+1 in g E)
Here we obviously cannot float the letbinding for w.
You may think rule (a) would never apply, because rule matching is
mostly invoked from the simplifier, when we have just run substExpr
over the argument, so there will be no shadowing anyway.
The fly in the ointment is that the forall'd variables of the
RULE itself are considered in scope.
I though of various ways to solve (a). One plan was to
clone the binders if they are in scope. But watch out!
(let x=y+1 in let z=x+1 in (z,z)
--> should match (p,p) but watch out that
the use of x on z's rhs is OK!
If we clone x, then the letbinding for 'z' is then caught by (b),
at least unless we elaborate the RnEnv stuff a bit.
So for we simply fail to match unless both (a) and (b) hold.
Other cases to think about
(let x=y+1 in \x. (x,x))
--> let x=y+1 in (\x1. (x1,x1))
(\x. let x = y+1 in (x,x))
--> let x1 = y+1 in (\x. (x1,x1)
(let x=y+1 in (x,x), let x=y1 in (x,x))
--> let x=y+1 in let x1=y1 in ((x,x),(x1,x1))
Note [Lookup inscope]
~~~~~~~~~~~~~~~~~~~~~~
Consider this example
foo :: Int -> Maybe Int -> Int
foo 0 (Just n) = n
foo m (Just n) = foo (mn) (Just n)
SpecConstr sees this fragment:
case w_smT of wild_Xf [Just A] {
Data.Maybe.Nothing -> lvl_smf;
Data.Maybe.Just n_acT [Just S(L)] ->
case n_acT of wild1_ams [Just A] { GHC.Base.I# y_amr [Just L] ->
\$wfoo_smW (GHC.Prim.-# ds_Xmb y_amr) wild_Xf
}};
and correctly generates the rule
RULES: "SC:$wfoo1" [0] __forall {y_amr [Just L] :: GHC.Prim.Int#
sc_snn :: GHC.Prim.Int#}
\$wfoo_smW sc_snn (Data.Maybe.Just @ GHC.Base.Int (GHC.Base.I# y_amr))
= \$s\$wfoo_sno y_amr sc_snn ;]
BUT we must ensure that this rule matches in the original function!
Note that the call to \$wfoo is
\$wfoo_smW (GHC.Prim.-# ds_Xmb y_amr) wild_Xf
During matching we expand wild_Xf to (Just n_acT). But then we must also
expand n_acT to (I# y_amr). And we can only do that if we look up n_acT
in the inscope set, because in wild_Xf's unfolding it won't have an unfolding
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
eqExpr env (Var v1) (Var v2)
| rnOccL env v1 == rnOccR env v2
= True
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}
%************************************************************************
%* *
Rulecheck the program
%* *
%************************************************************************
We want to know what sites have rules that could have fired but didn't.
This pass runs over the tree (without changing it) and reports such.
\begin{code}
ruleCheckProgram :: (Activation -> Bool)
-> String
-> RuleBase
-> [CoreBind]
-> SDoc
ruleCheckProgram is_active rule_pat rule_base 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 (RuleCheckEnv is_active rule_pat rule_base)) binds)
line = text (replicate 20 '-')
data RuleCheckEnv = RuleCheckEnv {
rc_is_active :: Activation -> Bool,
rc_pattern :: String,
rc_rule_base :: RuleBase
}
ruleCheckBind :: RuleCheckEnv -> CoreBind -> Bag SDoc
ruleCheckBind env (NonRec _ r) = ruleCheck env r
ruleCheckBind env (Rec prs) = unionManyBags [ruleCheck env r | (_,r) <- prs]
ruleCheck :: RuleCheckEnv -> CoreExpr -> Bag SDoc
ruleCheck _ (Var _) = emptyBag
ruleCheck _ (Lit _) = emptyBag
ruleCheck _ (Type _) = emptyBag
ruleCheck env (App f a) = ruleCheckApp env (App f a) []
ruleCheck env (Note _ e) = ruleCheck env e
ruleCheck env (Cast e _) = ruleCheck env e
ruleCheck env (Let bd e) = ruleCheckBind env bd `unionBags` ruleCheck env e
ruleCheck env (Lam _ e) = ruleCheck env e
ruleCheck env (Case e _ _ as) = ruleCheck env e `unionBags`
unionManyBags [ruleCheck env r | (_,_,r) <- as]
ruleCheckApp :: RuleCheckEnv -> Expr CoreBndr -> [Arg CoreBndr] -> Bag SDoc
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 _ = ruleCheck env other
\end{code}
\begin{code}
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)
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
=
vcat [text "Expression:" <+> ppr (mkApps (Var fn) args),
vcat (map check_rule 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 { 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 _ <- matchRule noBlackList 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"
| 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
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}