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Diffstat (limited to 'compiler/GHC/Core/Opt/DmdAnal.hs')
| -rw-r--r-- | compiler/GHC/Core/Opt/DmdAnal.hs | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/compiler/GHC/Core/Opt/DmdAnal.hs b/compiler/GHC/Core/Opt/DmdAnal.hs index ece13d894b..cf76563e3a 100644 --- a/compiler/GHC/Core/Opt/DmdAnal.hs +++ b/compiler/GHC/Core/Opt/DmdAnal.hs @@ -1940,6 +1940,12 @@ finaliseArgBoxities env fn threshold_arity rhs_dmds div rhs -- vcat [text "function:" <+> ppr fn -- , text "dmds before:" <+> ppr (map idDemandInfo (filter isId bndrs)) -- , text "dmds after: " <+> ppr arg_dmds' ]) $ + warnPprTrace (isJoinId fn && length rhs_dmds > threshold_arity) + "finaliseArgBoxities: excess rhs_dmds of join point" + (ppr fn <+> ppr threshold_arity <+> ppr rhs_dmds) $ + -- It is far from clear that it's OK to ignore excess rhs_dmds + -- here rather than zap all boxity. Hence we warn to collect + -- some examples. See Note [Threshold arity of join points] (arg_dmds', set_lam_dmds arg_dmds' rhs) -- set_lam_dmds: we must attach the final boxities to the lambda-binders -- of the function, both because that's kosher, and because CPR analysis |