diff options
Diffstat (limited to 'compiler/stranal/DmdAnal.lhs')
| -rw-r--r-- | compiler/stranal/DmdAnal.lhs | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/compiler/stranal/DmdAnal.lhs b/compiler/stranal/DmdAnal.lhs index 0bfd025410..ddeb1aa864 100644 --- a/compiler/stranal/DmdAnal.lhs +++ b/compiler/stranal/DmdAnal.lhs @@ -44,7 +44,7 @@ import UniqFM ( addToUFM_Directly, lookupUFM_Directly, minusUFM, filterUFM ) import Type ( isUnLiftedType, eqType, tyConAppTyCon_maybe ) import Coercion ( coercionKind ) -import Util ( mapAndUnzip, lengthIs, zipEqual ) +import Util import BasicTypes ( Arity, TopLevelFlag(..), isTopLevel, isNeverActive, RecFlag(..), isRec, isMarkedStrict ) import Maybes ( orElse, expectJust ) @@ -277,7 +277,7 @@ dmdAnal env dmd (Case scrut case_bndr ty alts) = let (alt_tys, alts') = mapAndUnzip (dmdAnalAlt env dmd) alts (scrut_ty, scrut') = dmdAnal env evalDmd scrut - (alt_ty, case_bndr') = annotateBndr (foldr1 lubType alt_tys) case_bndr + (alt_ty, case_bndr') = annotateBndr (foldr lubType botDmdType alt_tys) case_bndr res_ty = alt_ty `bothType` scrut_ty in -- pprTrace "dmdAnal:Case2" (vcat [ text "scrut" <+> ppr scrut @@ -592,7 +592,7 @@ mkSigTy top_lvl rec_flag id rhs dmd_ty maybe_id_dmd = idDemandInfo_maybe id -- Is Nothing the first time round - thunk_cpr_ok + thunk_cpr_ok -- See Note [CPR for thunks] | isTopLevel top_lvl = False -- Top level things don't get -- their demandInfo set at all | isRec rec_flag = False -- Ditto recursive things @@ -601,8 +601,8 @@ mkSigTy top_lvl rec_flag id rhs dmd_ty -- See notes below \end{code} -The thunk_cpr_ok stuff [CPR-AND-STRICTNESS] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Note [CPR for thunks] +~~~~~~~~~~~~~~~~~~~~~ If the rhs is a thunk, we usually forget the CPR info, because it is presumably shared (else it would have been inlined, and so we'd lose sharing if w/w'd it into a function). E.g. @@ -662,8 +662,8 @@ have a CPR in it or not. Simple solution: NB: strictly_demanded is never true of a top-level Id, or of a recursive Id. -The Nothing case in thunk_cpr_ok [CPR-AND-STRICTNESS] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Note [Optimistic in the Nothing case] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Demand info now has a 'Nothing' state, just like strictness info. The analysis works from 'dangerous' towards a 'safe' state; so we start with botSig for 'Nothing' strictness infos, and we start with @@ -1010,8 +1010,7 @@ extendSigsWithLam :: AnalEnv -> Id -> AnalEnv extendSigsWithLam env id = case idDemandInfo_maybe id of Nothing -> extendAnalEnv NotTopLevel env id cprSig - -- Optimistic in the Nothing case; - -- See notes [CPR-AND-STRICTNESS] + -- See Note [Optimistic in the Nothing case] Just (Eval (Prod _)) -> extendAnalEnv NotTopLevel env id cprSig _ -> env \end{code} |