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34fc50c1
by Ben Gamari at 2025-08-11T13:36:25-04:00
Kill IOPort#
This type is unnecessary, having been superceded by `MVar` and a rework
of WinIO's blocking logic.
See #20947.
See https://github.com/haskell/core-libraries-committee/issues/213.
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56b32c5a
by sheaf at 2025-08-12T10:00:19-04:00
Improve deep subsumption
This commit improves the DeepSubsumption sub-typing implementation
in GHC.Tc.Utils.Unify.tc_sub_type_deep by being less eager to fall back
to unification.
For example, we now are properly able to prove the subtyping relationship
((∀ a. a->a) -> Int) -> Bool <= β[tau] Bool
for an unfilled metavariable β. In this case (with an AppTy on the right),
we used to fall back to unification. No longer: now, given that the LHS
is a FunTy and that the RHS is a deep rho type (does not need any instantiation),
we try to make the RHS into a FunTy, viz.
β := (->) γ
We can then continue using covariance & contravariance of the function
arrow, which allows us to prove the subtyping relationship, instead of
trying to unify which would cause us to error out with:
Couldn't match expected type ‘β’ with actual type ‘(->) ((∀ a. a -> a) -> Int)
See Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify.
The other main improvement in this patch concerns type inference.
The main subsumption logic happens (before & after this patch) in
GHC.Tc.Gen.App.checkResultTy. However, before this patch, all of the
DeepSubsumption logic only kicked in in 'check' mode, not in 'infer' mode.
This patch adds deep instantiation in the 'infer' mode of checkResultTy
when we are doing deep subsumption, which allows us to accept programs
such as:
f :: Int -> (forall a. a->a)
g :: Int -> Bool -> Bool
test1 b =
case b of
True -> f
False -> g
test2 b =
case b of
True -> g
False -> f
See Note [Deeply instantiate in checkResultTy when inferring].
Finally, we add representation-polymorphism checks to ensure that the
lambda abstractions we introduce when doing subsumption obey the
representation polymorphism invariants of Note [Representation polymorphism invariants]
in GHC.Core. See Note [FunTy vs FunTy case in tc_sub_type_deep].
This is accompanied by a courtesy change to `(<.>) :: HsWrapper -> HsWrapper -> HsWrapper`,
adding the equation:
WpCast c1 <.> WpCast c2 = WpCast (c1 `mkTransCo` c2)
This is useful because mkWpFun does not introduce an eta-expansion when
both of the argument & result wrappers are casts; so this change allows
us to avoid introducing lambda abstractions when casts suffice.
Fixes #26225
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d175aff8
by Sylvain Henry at 2025-08-12T10:01:31-04:00
Add regression test for #18619
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a3983a26
by Sylvain Henry at 2025-08-12T10:02:20-04:00
RTS: remove some TSAN annotations (#20464)
Use RELAXED_LOAD_ALWAYS macro instead.
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0434af81
by Ben Gamari at 2025-08-12T10:03:02-04:00
Bump time submodule to 1.15
Also required bumps of Cabal, directory, and hpc.
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ff0c70ba
by Simon Peyton Jones at 2025-08-13T13:02:07-04:00
Make injecting implicit bindings into its own pass
Previously we were injecting "impliicit bindings" (data constructor
worker and wrappers etc)
- both at the end of CoreTidy,
- and at the start of CorePrep
This is unpleasant and confusing. This patch puts it it its own pass,
addImplicitBinds, which runs between the two.
The function `GHC.CoreToStg.AddImplicitBinds.addImplicitBinds` now takes /all/
TyCons, not just the ones for algebraic data types. That change ripples
through to
- corePrepPgm
- doCodeGen
- byteCodeGen
All take [TyCon] which includes all TyCons
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876aac38
by Simon Peyton Jones at 2025-08-13T13:02:08-04:00
Implement unary classes
The big change is described exhaustively in
Note [Unary class magic] in GHC.Core.TyCon
Other changes
* We never unbox class dictionaries in worker/wrapper. This has been true for some
time now, but the logic is now centralised in functions in
GHC.Core.Opt.WorkWrap.Utils, namely `canUnboxTyCon`, and `canUnboxArg`
See Note [Do not unbox class dictionaries] in GHC.Core.Opt.WorkWrap.Utils.
* Refactored the `notWorthFloating` logic in GHc.Core.Opt.SetLevels.
I can't remember if I actually changed any behaviour here, but if so it's
only in a corner cases.
* Fixed a bug in `GHC.Core.TyCon.isEnumerationTyCon`, which was wrongly returning
True for (##).
* Remove redundant Role argument to `liftCoSubstWithEx`. It was always
Representational.
* I refactored evidence generation in the constraint solver:
* Made GHC.Tc.Types.Evidence contain better abstactions for evidence
generation.
* I deleted the file `GHC.Tc.Types.EvTerm` and merged its (small) contents
elsewhere. It wasn't paying its way.
* Made evidence for implicit parameters go via a proper abstraction.
* Fix inlineBoringOk; see (IB6) in Note [inlineBoringOk]
This fixes a slowdown in `countdownEffectfulDynLocal`
in the `effectful` library.
Smaller things
* Rename `isDataTyCon` to `isBoxedDataTyCon`.
* GHC.Core.Corecion.liftCoSubstWithEx was only called with Representational role,
so I baked that into the function and removed the argument.
* Get rid of `GHC.Core.TyCon.tyConSingleAlgDataCon_maybe` in favour of calling
`not isNewTyCon` at the call sites; more explicit.
* Refatored `GHC.Core.TyCon.isInjectiveTyCon`; but I don't think I changed its
behaviour
* Moved `decomposeIPPred` to GHC.Core.Predicate
Compile time performance changes:
geo. mean +0.1%
minimum -6.8%
maximum +14.4%
The +14% one is in T21839c, where it seems that a bit more inlining
is taking place. That seems acceptable; and the average change is small
Metric Decrease:
LargeRecord
T12227
T12707
T16577
T21839r
T5642
Metric Increase:
T15164
T21839c
T3294
T5321FD
T5321Fun
WWRec
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9bf00666
by Simon Peyton Jones at 2025-08-13T13:02:46-04:00
Slight improvement to pre/postInlineUnconditionally
Avoids an extra simplifier iteration
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60db2c66
by Simon Peyton Jones at 2025-08-13T13:02:46-04:00
Fix a long-standing assertion error in normSplitTyConApp_maybe
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b2b95dce
by Simon Peyton Jones at 2025-08-13T13:02:46-04:00
Add comment to coercion optimiser