diff options
| author | Ben Gamari <ben@smart-cactus.org> | 2020-12-22 11:02:35 -0500 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-02-27 19:05:18 -0500 |
| commit | 382cd3b0c0a69d8e85e1588dc69b743c4a721818 (patch) | |
| tree | 0adee868f71d686455597a621c091a9b57f5d272 | |
| parent | 30500a4f8421ec7624316005f69c5ca252dbc37b (diff) | |
| download | haskell-382cd3b0c0a69d8e85e1588dc69b743c4a721818.tar.gz | |
Rewrite.split: Fix reboxing
As noted in #19102, we would previously ended up reboxing the tuple
result of `split`'s worker and then immediately take apart the boxed
tuple to again unpack it into an unboxed result.
Fixes #19102.
| -rw-r--r-- | compiler/GHC/Tc/Solver/Rewrite.hs | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/compiler/GHC/Tc/Solver/Rewrite.hs b/compiler/GHC/Tc/Solver/Rewrite.hs index 76500f0519..6300215d2a 100644 --- a/compiler/GHC/Tc/Solver/Rewrite.hs +++ b/compiler/GHC/Tc/Solver/Rewrite.hs @@ -1017,10 +1017,13 @@ split_pi_tys' :: Type -> ([TyCoBinder], Type, Bool) split_pi_tys' ty = split ty ty where -- put common cases first - split _ (ForAllTy b res) = let (bs, ty, _) = split res res + split _ (ForAllTy b res) = let -- This bang is necessary lest we see rather + -- terrible reboxing, as noted in #19102. + !(bs, ty, _) = split res res in (Named b : bs, ty, True) split _ (FunTy { ft_af = af, ft_mult = w, ft_arg = arg, ft_res = res }) - = let (bs, ty, named) = split res res + = let -- See #19102 + !(bs, ty, named) = split res res in (Anon af (mkScaled w arg) : bs, ty, named) split orig_ty ty | Just ty' <- coreView ty = split orig_ty ty' |