diff options
Diffstat (limited to 'compiler/coreSyn/CoreOpt.hs')
| -rw-r--r-- | compiler/coreSyn/CoreOpt.hs | 44 |
1 files changed, 2 insertions, 42 deletions
diff --git a/compiler/coreSyn/CoreOpt.hs b/compiler/coreSyn/CoreOpt.hs index 4240647d58..0f35e8f3ac 100644 --- a/compiler/coreSyn/CoreOpt.hs +++ b/compiler/coreSyn/CoreOpt.hs @@ -22,7 +22,7 @@ module CoreOpt ( import GhcPrelude -import CoreArity( joinRhsArity, etaExpandToJoinPoint ) +import CoreArity( etaExpandToJoinPoint ) import CoreSyn import CoreSubst @@ -646,58 +646,18 @@ joinPointBinding_maybe bndr rhs = Just (bndr, rhs) | AlwaysTailCalled join_arity <- tailCallInfo (idOccInfo bndr) - , not (bad_unfolding join_arity (idUnfolding bndr)) , (bndrs, body) <- etaExpandToJoinPoint join_arity rhs = Just (bndr `asJoinId` join_arity, mkLams bndrs body) | otherwise = Nothing - where - -- bad_unfolding returns True if we should /not/ convert a non-join-id - -- into a join-id, even though it is AlwaysTailCalled - -- See Note [Join points and INLINE pragmas] - bad_unfolding join_arity (CoreUnfolding { uf_src = src, uf_tmpl = rhs }) - = isStableSource src && join_arity > joinRhsArity rhs - bad_unfolding _ (DFunUnfolding {}) - = True - bad_unfolding _ _ - = False - joinPointBindings_maybe :: [(InBndr, InExpr)] -> Maybe [(InBndr, InExpr)] joinPointBindings_maybe bndrs = mapM (uncurry joinPointBinding_maybe) bndrs -{- Note [Join points and INLINE pragmas] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Consider - f x = let g = \x. not -- Arity 1 - {-# INLINE g #-} - in case x of - A -> g True True - B -> g True False - C -> blah2 - -Here 'g' is always tail-called applied to 2 args, but the stable -unfolding captured by the INLINE pragma has arity 1. If we try to -convert g to be a join point, its unfolding will still have arity 1 -(since it is stable, and we don't meddle with stable unfoldings), and -Lint will complain (see Note [Invariants on join points], (2a), in -CoreSyn. Trac #13413. - -Moreover, since g is going to be inlined anyway, there is no benefit -from making it a join point. - -If it is recursive, and uselessly marked INLINE, this will stop us -making it a join point, which is annoying. But occasionally -(notably in class methods; see Note [Instances and loop breakers] in -TcInstDcls) we mark recursive things as INLINE but the recursion -unravels; so ignoring INLINE pragmas on recursive things isn't good -either. - - -************************************************************************ +{- ********************************************************************* * * exprIsConApp_maybe * * |