\begin{code}
module Rules (
- RuleBase, prepareRuleBase, lookupRule,
- addIdSpecialisations,
- ProtoCoreRule(..), pprProtoCoreRule,
- orphanRule
+ RuleBase, emptyRuleBase,
+ extendRuleBaseList,
+ ruleBaseIds, pprRuleBase, ruleCheckProgram,
+
+ lookupRule, addRule, addIdSpecialisations
) where
#include "HsVersions.h"
import CoreSyn -- All of it
-import OccurAnal ( occurAnalyseExpr, tagBinders, UsageDetails )
-import BinderInfo ( markMany )
-import CoreFVs ( exprFreeVars, idRuleVars, ruleSomeLhsFreeVars )
+import OccurAnal ( occurAnalyseRule )
+import CoreFVs ( exprFreeVars, ruleRhsFreeVars )
import CoreUnfold ( isCheapUnfolding, unfoldingTemplate )
import CoreUtils ( eqExpr )
-import PprCore ( pprCoreRule )
-import Subst ( Subst, InScopeSet, substBndr, lookupSubst, extendSubst,
- mkSubst, substEnv, setSubstEnv, emptySubst, isInScope,
- unBindSubst, bindSubstList, unBindSubstList, substInScope
+import CoreTidy ( pprTidyIdRules )
+import Subst ( Subst, InScopeSet, mkInScopeSet, lookupSubst, extendSubst,
+ substEnv, setSubstEnv, emptySubst, isInScope, emptyInScopeSet,
+ bindSubstList, unBindSubstList, substInScope, uniqAway
)
-import Id ( Id, getIdUnfolding, zapLamIdInfo,
- getIdSpecialisation, setIdSpecialisation,
- setIdNoDiscard, maybeModifyIdInfo, modifyIdInfo
- )
-import IdInfo ( setSpecInfo, specInfo )
-import Name ( Name, isLocallyDefined )
-import Var ( isTyVar, isId )
+import Id ( Id, idUnfolding, idSpecialisation, setIdSpecialisation )
+import Var ( isId )
import VarSet
import VarEnv
-import Type ( mkTyVarTy, getTyVar_maybe )
-import qualified Unify ( match )
-import CmdLineOpts ( opt_D_dump_simpl, opt_D_verbose_core2core )
+import TcType ( mkTyVarTy )
+import qualified TcType ( match )
+import BasicTypes ( Activation, CompilerPhase, isActive )
-import UniqFM
-import ErrUtils ( dumpIfSet )
import Outputable
-import Maybes ( maybeToBool )
-import List ( partition )
-import Util ( sortLt )
+import FastString
+import Maybe ( isJust, isNothing, fromMaybe )
+import Util ( sortLe )
+import Bag
+import List ( isPrefixOf )
\end{code}
%************************************************************************
\begin{code}
-matchRules :: InScopeSet -> [CoreRule] -> [CoreExpr] -> Maybe (FAST_STRING, CoreExpr, [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 (FAST_STRING, CoreExpr, [CoreExpr])
+matchRule :: (Activation -> Bool) -> InScopeSet
+ -> CoreRule -> [CoreExpr] -> Maybe (RuleName, CoreExpr)
--- If (matchRule rule args) returns Just (name,rhs,args')
+-- If (matchRule rule args) returns Just (name,rhs)
-- then (f args) matches the rule, and the corresponding
--- rewritten RHS is (rhs args').
+-- rewritten RHS is rhs
--
-- The bndrs and rhs is occurrence-analysed
--
-- map (f.g) x) -- rhs
--
-- Then the call: matchRule the_rule [e1,map e2 e3]
--- = Just ("map/map", \f,g,x -> rhs, [e1,e2,e3])
+-- = Just ("map/map", (\f,g,x -> rhs) e1 e2 e3)
--
-- Any 'surplus' arguments in the input are simply put on the end
-- of the output.
-- (\x->E) matches (\x->F x)
-matchRule in_scope rule@(Rule rn tpl_vars tpl_args rhs) args
+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
= 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
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, mkLams tpl_vars rhs, mk_result_args subst tpl_vars)
- go [] args subst = Just (rn, mkLams tpl_vars rhs, mk_result_args subst tpl_vars ++ args)
+ 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
+ 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.
mk_result_args subst done)
Nothing -> Nothing -- Failure
where
- (done, leftovers) = partition (\v -> maybeToBool (lookupSubstEnv subst_env v))
+ (done, leftovers) = partition (\v -> isJust (lookupSubstEnv subst_env v))
(map zapOccInfo tpl_vars)
-- Zap the occ info
subst_env = substEnv subst
Nothing -> Nothing
eta_complete other vars = Nothing
--}
-
- -----------------------
- mk_result_args subst vs = map go vs
- where
- senv = substEnv subst
- go v = case lookupSubstEnv senv v of
- Just (DoneEx ex) -> ex
- Just (DoneTy ty) -> Type ty
- -- Substitution should bind them all!
zapOccInfo bndr | isTyVar bndr = bndr
| otherwise = zapLamIdInfo bndr
+-}
\end{code}
\begin{code}
-type Matcher result = IdOrTyVarSet -- Template variables
+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
kont (extendSubst subst v1 (DoneEx e2))
- | eqExpr (Var v1) e2 -> kont subst
+ | eqExpr (Var v1) e2 -> kont subst
-- v1 is not a template variable, so it must be a global constant
- Just (DoneEx e2') | eqExpr e2' e2 -> kont subst
+ Just (DoneEx e2') | eqExpr e2' e2 -> kont subst
other -> match_fail
-match (Con c1 es1) (Con c2 es2) tpl_vars kont subst
- | c1 == c2
- = matches es1 es2 tpl_vars kont subst
+match (Lit lit1) (Lit lit2) tpl_vars kont subst
+ | lit1 == lit2
+ = kont 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 (Case e1 x1 alts1) (Case e2 x2 alts2) tpl_vars kont subst
= match e1 e2 tpl_vars case_kont subst
where
- case_kont subst = bind [x1] [x2] (match_alts alts1 (sortLt lt_alt alts2))
+ case_kont subst = bind [x1] [x2] (match_alts alts1 (sortLe le_alt alts2))
tpl_vars kont subst
match (Type ty1) (Type ty2) tpl_vars kont subst
| isCheapUnfolding unfolding
= match e1 (unfoldingTemplate unfolding) tpl_vars kont subst
where
- unfolding = getIdUnfolding v2
+ unfolding = idUnfolding v2
-- We can't cope with lets in the template
subst
match_alts alts1 alts2 tpl_vars kont subst = match_fail
-lt_alt (con1, _, _) (con2, _, _) = con1 < con2
+le_alt (con1, _, _) (con2, _, _) = con1 <= con2
----------------------------------------
bind :: [CoreBndr] -- Template binders
subst' = bindSubstList subst vs1 vs2
-- The unBindSubst relies on no shadowing in the template
- not_in_subst v = not (maybeToBool (lookupSubst subst v))
+ not_in_subst v = isNothing (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)
\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 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
-- 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 str tpl_vars tpl_args rhs)
- = Rules (insert rules) (rhs_fvs `unionVarSet` new_rhs_fvs)
- where
- new_rule = Rule str tpl_vars' tpl_args rhs'
- -- Add occ info to tpl_vars, rhs
-
- (rhs_uds, rhs') = occurAnalyseExpr isLocallyDefined rhs
- (rhs_uds1, tpl_vars') = tagBinders rhs_uds tpl_vars
-
- insert [] = [new_rule]
- insert (rule:rules) | new_is_more_specific rule = (new_rule:rule:rules)
- | otherwise = rule : insert rules
-
- new_is_more_specific rule = maybeToBool (matchRule tpl_var_set rule tpl_args)
+addRule id (Rules rules rhs_fvs) rule@(BuiltinRule _ _)
+ = Rules (rule:rules) rhs_fvs
+ -- Put it at the start for lack of anything better
- tpl_var_set = mkVarSet tpl_vars'
- -- Actually we should probably include the free vars of tpl_args,
- -- but I can't be bothered
-
- new_rhs_fvs = (exprFreeVars rhs' `minusVarSet` tpl_var_set) `delVarSet` id
+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)
-addIdSpecialisations :: Id -> [([CoreBndr], [CoreExpr], CoreExpr)] -> Id
-addIdSpecialisations id spec_stuff
- = setIdSpecialisation id new_rules
+insertRule rules new_rule@(Rule _ _ tpl_vars tpl_args _)
+ = go rules
where
- rule_name = _PK_ ("SPEC " ++ showSDoc (ppr id))
- new_rules = foldr add (getIdSpecialisation id) spec_stuff
- add (vars, args, rhs) rules = addRule id rules (Rule rule_name vars args rhs)
+ 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{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 (Just fn) rule
-
-lookupRule :: InScopeSet -> Id -> [CoreExpr] -> Maybe (FAST_STRING, CoreExpr, [CoreExpr])
-lookupRule in_scope fn args
- = case getIdSpecialisation fn of
- Rules rules _ -> matchRules in_scope rules args
-
-orphanRule :: ProtoCoreRule -> Bool
--- An "orphan rule" is one that is defined in this
--- module, but of ran *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
+ -> 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
\end{code}
%************************************************************************
%* *
-\subsection{Getting the rules ready}
+\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}
-type RuleBase = (IdSet, -- Imported Ids that have rules attached
- IdSet) -- Ids (whether local or imported) mentioned on
- -- LHS of some rule; these should be black listed
+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}
--- 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
+\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
-prepareRuleBase :: [CoreBind] -> [ProtoCoreRule] -> ([CoreBind], RuleBase)
-prepareRuleBase binds rules
- = (map zap_bind binds, (imported_rule_ids, rule_lhs_fvs))
+ruleCheckFun (phase, pat) fn args
+ | null name_match_rules = emptyBag
+ | otherwise = unitBag (ruleAppCheck_help phase fn args name_match_rules)
where
- (rule_ids, rule_lhs_fvs) = foldr add_rule (emptyVarSet, emptyVarSet) rules
- imported_rule_ids = filterVarSet (not . isLocallyDefined) rule_ids
-
- -- rule_fvs is the set of all variables mentioned in 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
-
-add_rule (ProtoCoreRule _ id rule)
- (rule_id_set, rule_fvs)
- = (rule_id_set `extendVarSet` new_id,
- rule_fvs `unionVarSet` extendVarSet lhs_fvs id)
+ 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
- new_id = case lookupVarSet rule_id_set id of
- Just id' -> addRuleToId id' rule
- Nothing -> addRuleToId id rule
- lhs_fvs = ruleSomeLhsFreeVars isId rule
- -- Find *all* the free Ids of the LHS, not just
- -- locally defined ones!!
-
-addRuleToId id rule = setIdSpecialisation id (addRule id (getIdSpecialisation id) rule)
+ 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 the 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))]
+
+ bndr_set = mkVarSet rule_bndrs
+ match_fn rule_arg arg = match rule_arg arg bndr_set (\s -> Just ()) emptySubst
\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.
+
+pprRuleBase :: RuleBase -> SDoc
+pprRuleBase (RuleBase rules) = vcat [ pprTidyIdRules id | id <- varSetElems rules ]
+\end{code}
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