import CoreFVs ( idRuleVars )
import CoreUtils ( exprIsTrivial )
import Const ( Con(..), Literal(..) )
-import Id ( isSpecPragmaId,
- getInlinePragma, setInlinePragma,
+import Id ( isSpecPragmaId, isOneShotLambda, setOneShotLambda,
+ getIdOccInfo, setIdOccInfo,
isExportedId, modifyIdInfo, idInfo,
getIdSpecialisation,
idType, idUnique, Id
)
-import IdInfo ( InlinePragInfo(..), OccInfo(..), copyIdInfo )
+import IdInfo ( OccInfo(..), insideLam, copyIdInfo )
import VarSet
import VarEnv
-- Common case of simple self-recursion
reOrderRec env (CyclicSCC [bind])
- = [(setInlinePragma tagged_bndr IAmALoopBreaker, rhs)]
+ = [(setIdOccInfo tagged_bndr IAmALoopBreaker, rhs)]
where
((tagged_bndr, rhs), _, _) = bind
-- do SCC analysis on the rest, and recursively sort them out
concat (map (reOrderRec env) (stronglyConnCompR unchosen))
++
- [(setInlinePragma tagged_bndr IAmALoopBreaker, rhs)]
+ [(setIdOccInfo tagged_bndr IAmALoopBreaker, rhs)]
where
(chosen_pair, unchosen) = choose_loop_breaker bind (score bind) [] binds
inlineCandidate :: Id -> CoreExpr -> Bool
inlineCandidate id (Note InlineMe _) = True
- inlineCandidate id rhs = case getInlinePragma id of
- IMustBeINLINEd -> True
- ICanSafelyBeINLINEd _ _ -> True
- other -> False
+ inlineCandidate id rhs = case getIdOccInfo id of
+ OneOcc _ _ -> True
+ other -> False
-- Real example (the Enum Ordering instance from PrelBase):
-- rec f = \ x -> case d of (p,q,r) -> p x
= case occAnal (env_body `addNewCands` binders) body of { (body_usage, body') ->
let
(final_usage, tagged_binders) = tagBinders body_usage binders
+ -- URGH! Sept 99: we don't seem to be able to use binders' here, because
+ -- we get linear-typed things in the resulting program that we can't handle yet.
+ -- (e.g. PrelShow) TODO
+
really_final_usage = if linear then
final_usage
else
mkLams tagged_binders body') }
where
(binders, body) = collectBinders expr
- (linear, env_body) = getCtxt env (count isId binders)
+ (linear, env_body, binders') = oneShotGroup env binders
occAnal env (Case scrut bndr alts)
= case mapAndUnzip (occAnalAlt alt_env) alts of { (alts_usage_s, alts') ->
case occAnal (zapCtxt env) scrut of { (scrut_usage, scrut') ->
let
alts_usage = foldr1 combineAltsUsageDetails alts_usage_s
- (alts_usage1, tagged_bndr) = tagBinder alts_usage bndr
+ alts_usage' = addCaseBndrUsage alts_usage
+ (alts_usage1, tagged_bndr) = tagBinder alts_usage' bndr
total_usage = scrut_usage `combineUsageDetails` alts_usage1
in
total_usage `seq` (total_usage, Case scrut' tagged_bndr alts') }}
where
alt_env = env `addNewCand` bndr
+ -- The case binder gets a usage of either "many" or "dead", never "one".
+ -- Reason: we like to inline single occurrences, to eliminate a binding,
+ -- but inlining a case binder *doesn't* eliminate a binding.
+ -- We *don't* want to transform
+ -- case x of w { (p,q) -> f w }
+ -- into
+ -- case x of w { (p,q) -> f (p,q) }
+ addCaseBndrUsage usage = case lookupVarEnv usage bndr of
+ Nothing -> usage
+ Just occ -> extendVarEnv usage bndr (markMany occ)
+
occAnal env (Let bind body)
= case occAnal new_env body of { (body_usage, body') ->
case occAnalBind env bind body_usage of { (final_usage, new_binds) ->
setCtxt :: OccEnv -> CtxtTy -> OccEnv
setCtxt (OccEnv ifun cands _) ctxt = OccEnv ifun cands ctxt
-getCtxt :: OccEnv -> Int -> (Bool, OccEnv) -- True <=> this is a linear lambda
- -- The Int is the number of lambdas
-getCtxt env@(OccEnv ifun cands []) n = (False, env)
-getCtxt (OccEnv ifun cands ctxt) n = (and (take n ctxt), OccEnv ifun cands (drop n ctxt))
- -- Only return True if *all* the lambdas are linear
+oneShotGroup :: OccEnv -> [CoreBndr] -> (Bool, OccEnv, [CoreBndr])
+ -- True <=> this is a one-shot linear lambda group
+ -- The [CoreBndr] are the binders.
+
+ -- The result binders have one-shot-ness set that they might not have had originally.
+ -- This happens in (build (\cn -> e)). Here the occurrence analyser
+ -- linearity context knows that c,n are one-shot, and it records that fact in
+ -- the binder. This is useful to guide subsequent float-in/float-out tranformations
+
+oneShotGroup (OccEnv ifun cands ctxt) bndrs
+ = case go ctxt bndrs [] of
+ (new_ctxt, new_bndrs) -> (all is_one_shot new_bndrs, OccEnv ifun cands new_ctxt, new_bndrs)
+ where
+ is_one_shot b = isId b && isOneShotLambda b
+
+ go ctxt [] rev_bndrs = (ctxt, reverse rev_bndrs)
+
+ go (lin_ctxt:ctxt) (bndr:bndrs) rev_bndrs
+ | isId bndr = go ctxt bndrs (bndr':rev_bndrs)
+ where
+ bndr' | lin_ctxt = setOneShotLambda bndr
+ | otherwise = bndr
+
+ go ctxt (bndr:bndrs) rev_bndrs = go ctxt bndrs (bndr:rev_bndrs)
+
zapCtxt env@(OccEnv ifun cands []) = env
zapCtxt (OccEnv ifun cands _ ) = OccEnv ifun cands []
tagBinders usage binders
= let
usage' = usage `delVarEnvList` binders
- uss = map (setBinderPrag usage) binders
+ uss = map (setBinderOcc usage) binders
in
usage' `seq` (usage', uss)
tagBinder usage binder
= let
usage' = usage `delVarEnv` binder
- binder' = setBinderPrag usage binder
+ binder' = setBinderOcc usage binder
in
usage' `seq` (usage', binder')
-setBinderPrag :: UsageDetails -> CoreBndr -> CoreBndr
-setBinderPrag usage bndr
- | isTyVar bndr
- = bndr
-
- | otherwise
- = case old_prag of
- NoInlinePragInfo -> new_bndr
- IAmDead -> new_bndr -- The next three are annotations
- ICanSafelyBeINLINEd _ _ -> new_bndr -- from the previous iteration of
- IAmALoopBreaker -> new_bndr -- the occurrence analyser
-
- other | its_now_dead -> new_bndr -- Overwrite the others iff it's now dead
- | otherwise -> bndr
-
+setBinderOcc :: UsageDetails -> CoreBndr -> CoreBndr
+setBinderOcc usage bndr
+ | isTyVar bndr = bndr
+ | isExportedId bndr
+ = -- Don't use local usage info for visible-elsewhere things
+ -- BUT *do* erase any IAmALoopBreaker annotation, because we're
+ -- about to re-generate it and it shouldn't be "sticky"
+ case getIdOccInfo bndr of
+ NoOccInfo -> bndr
+ other -> setIdOccInfo bndr NoOccInfo
+
+ | otherwise = setIdOccInfo bndr occ_info
where
- old_prag = getInlinePragma bndr
- new_bndr = setInlinePragma bndr new_prag
-
- its_now_dead = case new_prag of
- IAmDead -> True
- other -> False
-
- new_prag = occInfoToInlinePrag occ_info
-
- occ_info
- | isExportedId bndr = noBinderInfo
- -- Don't use local usage info for visible-elsewhere things
- -- But NB that we do set NoInlinePragma for exported things
- -- thereby nuking any IAmALoopBreaker from a previous pass.
-
- | otherwise = case lookupVarEnv usage bndr of
- Nothing -> deadOccurrence
- Just info -> info
+ occ_info = case lookupVarEnv usage bndr of
+ Nothing -> IAmDead
+ Just info -> binderInfoToOccInfo info
markBinderInsideLambda :: CoreBndr -> CoreBndr
markBinderInsideLambda bndr
= bndr
| otherwise
- = case getInlinePragma bndr of
- ICanSafelyBeINLINEd not_in_lam nalts
- -> bndr `setInlinePragma` ICanSafelyBeINLINEd InsideLam nalts
- other -> bndr
+ = case getIdOccInfo bndr of
+ OneOcc _ once -> bndr `setIdOccInfo` OneOcc insideLam once
+ other -> bndr
funOccZero = funOccurrence 0
\end{code}
projects / ghc-hetmet.git / blobdiff