diff options
| -rw-r--r-- | compiler/simplCore/OccurAnal.lhs | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/compiler/simplCore/OccurAnal.lhs b/compiler/simplCore/OccurAnal.lhs index ae2b7b9023..5ed57fbe92 100644 --- a/compiler/simplCore/OccurAnal.lhs +++ b/compiler/simplCore/OccurAnal.lhs @@ -308,12 +308,10 @@ reOrderCycle bndrs (bind : binds) -- Also vital to avoid risk of divergence: -- Note [Recursive rules] - | is_con_app rhs = 2 -- Data types help with cases - -- This used to have a lower score than inlineCandidate, but - -- it's *really* helpful if dictionaries get inlined fast, - -- so I'm experimenting with giving higher priority to data-typed things + | inlineCandidate bndr rhs = 2 -- Likely to be inlined + -- Note [Inline candidates] - | inlineCandidate bndr rhs = 1 -- Likely to be inlined + | is_con_app rhs = 1 -- Data types help with cases | otherwise = 0 @@ -356,6 +354,25 @@ makeLoopBreaker bndrs rhs_usg bndr rules_only = bndrs `intersectsUFM` rhs_usg \end{code} +Note [Inline candidates] +~~~~~~~~~~~~~~~~~~~~~~~~ +At one point I gave is_con_app a higher score than inline-candidate, +on the grounds that "it's *really* helpful if dictionaries get inlined fast". +However a nofib run revealed no change if they were swapped so that +inline-candidate has the higher score. And it's important that it does, +else you can get a bad worker-wrapper split thus: + rec { + $wfoo x = ....foo x.... + + {-loop brk-} foo x = ...$wfoo x... + } +But we *want* the wrapper to be inlined! If it isn't, the interface +file sees the unfolding for $wfoo, and sees that foo is strict (and +hence it gets an auto-generated wrapper. Result: an infinite inlining +in the importing scope. So be a bit careful if you change this. A +good example is Tree.repTree in nofib/spectral/minimax. If is_con_app +has the higher score, then compiling Game.hs goes into an infinite loop. + Note [Recursive rules] ~~~~~~~~~~~~~~~~~~~~~~ Consider this group, which is typical of what SpecConstr builds: |