[Git][ghc/ghc][wip/T23083] 53 commits: rts: Ensure non-moving gc is not running when pausing

Wed May 17 14:01:40 UTC 2023

Sebastian Graf pushed to branch wip/T23083 at Glasgow Haskell Compiler / GHC

Commits:
aa84cff4 by Teo Camarasu at 2023-05-12T19:27:23-04:00
rts: Ensure non-moving gc is not running when pausing

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5ad776ab by Teo Camarasu at 2023-05-12T19:27:23-04:00
rts: Teach listAllBlocks about nonmoving heap

List all blocks on the non-moving heap.

Resolves #22627

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d683b2e5 by Krzysztof Gogolewski at 2023-05-12T19:28:00-04:00
Fix coercion optimisation for SelCo (#23362)

setNominalRole_maybe is supposed to output a nominal coercion.
In the SelCo case, it was not updating the stored role to Nominal,
causing #23362.

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59aa4676 by Alexis King at 2023-05-12T19:28:47-04:00
hadrian: Fix linker script flag for MergeObjects builder

This fixes what appears to have been a typo in !9530. The `-t` flag just
enables tracing on all versions of `ld` I’ve looked at, while `-T` is
used to specify a linker script. It seems that this worked anyway for
some reason on some `ld` implementations (perhaps because they
automatically detect linker scripts), but the missing `-T` argument
causes `gold` to complain.

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4bf9fa0f by Adam Gundry at 2023-05-12T23:49:49-04:00
Less coercion optimization for non-newtype axioms

See Note [Push transitivity inside newtype axioms only] for an explanation
of the change here.  This change substantially improves the performance of
coercion optimization for programs involving transitive type family reductions.

-------------------------
Metric Decrease:
    CoOpt_Singletons
    LargeRecord
    T12227
    T12545
    T13386
    T15703
    T5030
    T8095
-------------------------

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dc0c9574 by Adam Gundry at 2023-05-12T23:49:49-04:00
Move checkAxInstCo to GHC.Core.Lint

A consequence of the previous change is that checkAxInstCo is no longer
called during coercion optimization, so it can be moved back where it belongs.

Also includes some edits to Note [Conflict checking with AxiomInstCo] as
suggested by @simonpj.

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8b9b7dbc by Simon Peyton Jones at 2023-05-12T23:50:25-04:00
Use the eager unifier in the constraint solver

This patch continues the refactoring of the constraint solver
described in #23070.

The Big Deal in this patch is to call the regular, eager unifier from the
constraint solver, when we want to create new equalities. This
replaces the existing, unifyWanted which amounted to
yet-another-unifier, so it reduces duplication of a rather subtle
piece of technology. See

  * Note [The eager unifier] in GHC.Tc.Utils.Unify
  * GHC.Tc.Solver.Monad.wrapUnifierTcS

I did lots of other refactoring along the way

* I simplified the treatment of right hand sides that contain CoercionHoles.
  Now, a constraint that contains a hetero-kind CoercionHole is non-canonical,
  and cannot be used for rewriting or unification alike.  This required me
  to add the ch_hertero_kind flag to CoercionHole, with consequent knock-on
  effects. See wrinkle (2) of `Note [Equalities with incompatible kinds]` in
  GHC.Tc.Solver.Equality.

* I refactored the StopOrContinue type to add StartAgain, so that after a
  fundep improvement (for example) we can simply start the pipeline again.

* I got rid of the unpleasant (and inefficient) rewriterSetFromType/Co functions.
  With Richard I concluded that they are never needed.

* I discovered Wrinkle (W1) in Note [Wanteds rewrite Wanteds] in
  GHC.Tc.Types.Constraint, and therefore now prioritise non-rewritten equalities.

Quite a few error messages change, I think always for the better.

Compiler runtime stays about the same, with one outlier: a 17% improvement in T17836

Metric Decrease:
    T17836
    T18223

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5cad28e7 by Bartłomiej Cieślar at 2023-05-12T23:51:06-04:00
Cleanup of dynflags override in export renaming
The deprecation warnings are normally emitted whenever the name's GRE is being looked up, which calls the GHC.Rename.Env.addUsedGRE function. We do not want those warnings to be emitted when renaming export lists, so they are artificially turned off by removing all warning categories from DynFlags at the beginning of GHC.Tc.Gen.Export.rnExports. This commit removes that dependency by unifying the function used for GRE lookup in lookup_ie to lookupGreAvailRn and disabling the call to addUsedGRE in said function (the warnings are also disabled in a call to lookupSubBndrOcc_helper in lookupChildrenExport), as per #17957. This commit also changes the setting for whether to warn about deprecated names in addUsedGREs to be an explicit enum instead of a boolean.

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d85ed900 by Alexis King at 2023-05-13T08:45:18-04:00
Use a uniform return convention in bytecode for unary results

fixes #22958

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8a0d45f7 by Bodigrim at 2023-05-13T08:45:58-04:00
Add more instances for Compose: Enum, Bounded, Num, Real, Integral

See https://github.com/haskell/core-libraries-committee/issues/160 for discussion

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902f0730 by Simon Peyton Jones at 2023-05-13T14:58:34-04:00
Make GHC.Types.Id.Make.shouldUnpackTy a bit more clever

As #23307, GHC.Types.Id.Make.shouldUnpackTy was leaving money on the
table, failing to unpack arguments that are perfectly unpackable.

The fix is pretty easy; see Note [Recursive unboxing]

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a5451438 by sheaf at 2023-05-13T14:59:13-04:00
Fix bad multiplicity role in tyConAppFunCo_maybe

The function tyConAppFunCo_maybe produces a multiplicity coercion
for the multiplicity argument of the function arrow, except that
it could be at the wrong role if asked to produce a representational
coercion. We fix this by using the 'funRole' function, which computes
the right roles for arguments to the function arrow TyCon.

Fixes #23386

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5b9e9300 by sheaf at 2023-05-15T11:26:59-04:00
Turn "ambiguous import" error into a panic

This error should never occur, as a lookup of a type or data constructor
should never be ambiguous. This is because a single module cannot export
multiple Names with the same OccName, as per item (1) of
Note [Exporting duplicate declarations] in GHC.Tc.Gen.Export.

This code path was intended to handle duplicate record fields, but the
rest of the code had since been refactored to handle those in a
different way.

We also remove the AmbiguousImport constructor of IELookupError, as
it is no longer used.

Fixes #23302

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e305e60c by M Farkas-Dyck at 2023-05-15T11:27:41-04:00
Unbreak some tests with latest GNU grep, which now warns about stray '\'.

Confusingly, the testsuite mangled the error to say "stray /".

We also migrate some tests from grep to grep -E, as it seems the author actually wanted an "POSIX extended" (a.k.a. sane) regex.

Background: POSIX specifies 2 "regex" syntaxen: "basic" and "extended". Of these, only "extended" syntax is actually a regular expression. Furthermore, "basic" syntax is inconsistent in its use of the '\' character — sometimes it escapes a regex metacharacter, but sometimes it unescapes it, i.e. it makes an otherwise normal character become a metacharacter. This baffles me and it seems also the authors of these tests. Also, the regex(7) man page (at least on Linux) says "basic" syntax is obsolete. Nearly all modern tools and libraries are consistent in this use of the '\' character (of which many use "extended" syntax by default).

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5ae81842 by sheaf at 2023-05-15T14:49:17-04:00
Improve "ambiguous occurrence" error messages

This error was sometimes a bit confusing, especially when data families
were involved. This commit improves the general presentation of the
"ambiguous occurrence" error, and adds a bit of extra context in the
case of data families.

Fixes #23301

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2f571afe by Sylvain Henry at 2023-05-15T14:50:07-04:00
Fix GHCJS OS platform (fix #23346)

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86aae570 by Oleg Grenrus at 2023-05-15T14:50:43-04:00
Split DynFlags structure into own module

This will allow to make command line parsing to depend on
diagnostic system (which depends on dynflags)

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fbe3fe00 by Josh Meredith at 2023-05-15T18:01:43-04:00
Replace the implementation of CodeBuffers with unboxed types

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21f3aae7 by Josh Meredith at 2023-05-15T18:01:43-04:00
Use unboxed codebuffers in base

Metric Decrease:
    encodingAllocations

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18ea2295 by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Weak pointer cleanups

Various stylistic cleanups. No functional changes.

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c343112f by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Don't force debug output to stderr

Previously `+RTS -Dw -l` would emit debug output to the eventlog while
`+RTS -l -Dw` would emit it to stderr. This was because the parser for
`-D` would unconditionally override the debug output target. Now we
instead only do so if no it is currently `TRACE_NONE`.

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a5f5f067 by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Forcibly flush eventlog on barf

Previously we would attempt to flush via `endEventLogging` which can
easily deadlock, e.g., if `barf` fails during GC.

Using `flushEventLog` directly may result in slightly less consistent
eventlog output (since we don't take all capabilities before flushing)
but avoids deadlocking.

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73b1e87c by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Assert that pointers aren't cleared by -DZ

This turns many segmentation faults into much easier-to-debug assertion
failures by ensuring that LOOKS_LIKE_*_PTR checks recognize bit-patterns
produced by `+RTS -DZ` clearing as invalid pointers.

This is a bit ad-hoc but this is the debug runtime.

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37fb61d8 by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Introduce printGlobalThreads

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451d65a6 by Ben Gamari at 2023-05-15T18:02:20-04:00
rts: Don't sanity-check StgTSO.global_link

See Note [Avoid dangling global_link pointers].

Fixes #19146.

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d69cbd78 by sheaf at 2023-05-15T18:03:00-04:00
Split up tyThingToIfaceDecl from GHC.Iface.Make

This commit moves tyThingToIfaceDecl and coAxiomToIfaceDecl
from GHC.Iface.Make into GHC.Iface.Decl.
This avoids GHC.Types.TyThing.Ppr, which needs tyThingToIfaceDecl,
transitively depending on e.g. GHC.Iface.Load and GHC.Tc.Utils.Monad.

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4d29ecdf by sheaf at 2023-05-15T18:03:00-04:00
Migrate errors to diagnostics in GHC.Tc.Module

This commit migrates the errors in GHC.Tc.Module to use the new
diagnostic infrastructure.

It required a significant overhaul of the compatibility checks between
an hs-boot or signature module and its implementation; we now use
a Writer monad to accumulate errors; see the BootMismatch datatype
in GHC.Tc.Errors.Types, with its panoply of subtypes.
For the sake of readability, several local functions inside the
'checkBootTyCon' function were split off into top-level functions.

We split off GHC.Types.HscSource into a "boot or sig" vs "normal hs file"
datatype, as this mirrors the logic in several other places where we
want to treat hs-boot and hsig files in a similar fashion.

This commit also refactors the Backpack checks for type synonyms
implementing abstract data, to correctly reject implementations that
contain qualified or quantified types (this fixes #23342 and #23344).

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d986c98e by Rodrigo Mesquita at 2023-05-16T00:14:04-04:00
configure: Drop unused AC_PROG_CPP

In configure, we were calling `AC_PROG_CPP` but never making use of the
$CPP variable it sets or reads.

The issue is $CPP will show up in the --help output of configure,
falsely advertising a configuration option that does nothing.

The reason we don't use the $CPP variable is because HS_CPP_CMD is
expected to be a single command (without flags), but AC_PROG_CPP, when
CPP is unset, will set said variable to something like `/usr/bin/gcc -E`.
Instead, we configure HS_CPP_CMD through $CC.

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a8f0435f by Cheng Shao at 2023-05-16T00:14:42-04:00
rts: fix --disable-large-address-space

This patch moves
ACQUIRE_ALLOC_BLOCK_SPIN_LOCK/RELEASE_ALLOC_BLOCK_SPIN_LOCK from
Storage.h to HeapAlloc.h. When --disable-large-address-space is passed
to configure, the code in HeapAlloc.h makes use of these two macros.
Fixes #23385.

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bdb93cd2 by Oleg Grenrus at 2023-05-16T07:59:21+03:00
Add -Wmissing-role-annotations

Implements #22702

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41ecfc34 by Ben Gamari at 2023-05-16T07:28:15-04:00
base: Export {get,set}ExceptionFinalizer from System.Mem.Weak

As proposed in CLC Proposal #126 [1].

[1]: https://github.com/haskell/core-libraries-committee/issues/126

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67330303 by Ben Gamari at 2023-05-16T07:28:16-04:00
base: Introduce printToHandleFinalizerExceptionHandler

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5e3f9bb5 by Josh Meredith at 2023-05-16T13:59:22-04:00
JS: Implement h$clock_gettime in the JavaScript RTS (#23360)

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90e69d5d by Zubin Duggal at 2023-05-16T14:00:00-04:00
compiler: Use compact representation for SourceText

SourceText is serialized along with INLINE pragmas into interface files. Many of
these SourceTexts are identical, for example "{-# INLINE#". When deserialized,
each such SourceText was previously expanded out into a [Char], which is highly
wasteful of memory, and each such instance of the text would allocate an
independent list with its contents as deserializing breaks any sharing that might
have existed.

Instead, we use a `FastString` to represent these, so that each instance unique
text will be interned and stored in a memory efficient manner.

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b70bc690 by Zubin Duggal at 2023-05-16T14:00:00-04:00
compiler: Use compact representation/FastStrings for `SourceNote`s

`SourceNote`s should not be stored as [Char] as this is highly wasteful
and in certain scenarios can be highly duplicated.

Metric Decrease:
  hard_hole_fits

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6231a126 by Zubin Duggal at 2023-05-16T14:00:00-04:00
compiler: Use compact representation for UsageFile (#22744)

Use FastString to store filepaths in interface files, as this data is
highly redundant so we want to share all instances of filepaths in the
compiler session.

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47a58150 by Zubin Duggal at 2023-05-16T14:00:00-04:00
testsuite: add test for T22744

This test checks for #22744 by compiling 100 modules which each have
a dependency on 1000 distinct external files.

Previously, when loading these interfaces from disk, each individual instance
of a filepath in the interface will would be allocated as an individual object
on the heap, meaning we have heap objects for 100*1000 files, when there are
only 1000 distinct files we care about.

This test checks this by first compiling the module normally, then measuring
the peak memory usage in a no-op recompile, as the recompilation checking will
force the allocation of all these filepaths.

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0451bdc9 by Ben Gamari at 2023-05-16T21:31:40-04:00
users guide: Add glossary

Currently this merely explains the meaning of "technology preview" in
the context of released features.

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0ba52e4e by Ben Gamari at 2023-05-16T21:31:40-04:00
Update glossary.rst
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3d23060c by Ben Gamari at 2023-05-16T21:31:40-04:00
Use glossary directive
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2972fd66 by Sylvain Henry at 2023-05-16T21:32:20-04:00
JS: fix getpid (fix #23399)

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7f7cdbe5 by Sebastian Graf at 2023-05-17T11:10:26+02:00
Cleanup a TODO introduced in 1f94e0f7

The change must have slipped through review of !4412

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656f007e by Sebastian Graf at 2023-05-17T11:10:26+02:00
More explicit strictness in GHC.Real

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d1a56c6a by Sebastian Graf at 2023-05-17T11:10:26+02:00
exprIsTrivial: Factor out shared implementation

The duplication between `exprIsTrivial` and `getIdFromTrivialExpr_maybe` has
been bugging me for a long time.

This patch introduces an inlinable worker function `trivial_expr_fold` acting
as the single, shared decision procedure of triviality. It "returns" a
Church-encoded `Maybe (Maybe Id)`, so when it is inlined, it fuses to similar
code as before.
(Better code, even, in the case of `getIdFromTrivialExpr` which presently
allocates a `Just` constructor that cancels away after this patch.)

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b2a95018 by Sebastian Graf at 2023-05-17T11:10:26+02:00
Simplify: Simplification of arguments in a single function

The Simplifier had a function `simplArg` that wasn't called in `rebuildCall`,
which seems to be the main way to simplify args. Hence I consolidated the code
path to call `simplArg`, too, renaming to `simplLazyArg`.

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b3c30fea by Sebastian Graf at 2023-05-17T11:10:27+02:00
Core.Ppr: Omit case binder for empty case alternatives

A minor improvement to pretty-printing

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f76c3b53 by Sebastian Graf at 2023-05-17T11:10:27+02:00
Disable test RepPolyWrappedVar2 in JS backend

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790406b1 by Sebastian Graf at 2023-05-17T11:10:27+02:00
Inlining literals into boring contexts is OK

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bcd1c835 by Sebastian Graf at 2023-05-17T11:10:27+02:00
Kill SetLevel.notWorthFloating.is_triv (#23270)

We have had it since b84ba676034, when it operated on annotated expressions.
Nowadays it operates on vanilla `CoreExpr` though, so we should just call
`exprIsTrivial`; thus handling empty cases and string literals correctly.

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6ea01c67 by Sebastian Graf at 2023-05-17T16:00:30+02:00
ANFise string literal arguments (#23270)

This instates the invariant that a trivial CoreExpr translates to an atomic
StgExpr. Nice.

Fixes #23270.

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5e67e819 by Sebastian Graf at 2023-05-17T16:00:30+02:00
Deactivate -fcatch-nonexhaustive-cases in ghc-bignum (#23345)

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e2158d34 by Sebastian Graf at 2023-05-17T16:01:08+02:00
CorePrep: Eliminate EmptyCase and unsafeEqualityProof in CoreToStg instead

We eliminate EmptyCase by way of `coreToStg (Case e _ _ []) = coreToStg e` now.
The main reason is that it plays far better in conjunction with eta expansion
(as we aim to do for arguments in CorePrep, #23083), because we can discard
any arguments, `(case e of {}) eta == case e of {}`, whereas in `(e |> co) eta`
it's impossible to discard the argument.

We do also give the same treatment to unsafeCoerce proofs and treat them as
trivial iff their RHS is trivial.

It is also both much simpler to describe than the previous mechanism of emitting
an unsafe coercion and simpler to implement, removing quite a bit of commentary
and `CorePrepProv`.

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ff4a6c2e by Sebastian Graf at 2023-05-17T16:01:08+02:00
CorePrep: Eta expand arguments (#23083)

Previously, we'd only eta expand let bindings and lambdas,
now we'll also eta expand arguments such as in T23083:
```hs
g f h = f (h `seq` (h $))
```
Unless `-fpedantic-bottoms` is set, we'll now transform to
```hs
g f h = f (\eta -> h eta)
```
in CorePrep.

See the new `Note [Eta expansion of arguments in CorePrep]` for the details.

We only do this optimisation with -O2 because we saw 2-3% ghc/alloc regressions
in T4801 and T5321FD.

Fixes #23083.

- - - - -

30 changed files:

- compiler/GHC/ByteCode/Asm.hs
- compiler/GHC/ByteCode/Instr.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
- compiler/GHC/CmmToAsm/Dwarf.hs
- compiler/GHC/CmmToAsm/PPC/CodeGen.hs
- compiler/GHC/CmmToAsm/X86/CodeGen.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion.hs-boot
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/FVs.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/CallerCC.hs
- compiler/GHC/Core/Opt/Monad.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/WorkWrap.hs
- compiler/GHC/Core/Ppr.hs
- compiler/GHC/Core/Predicate.hs
- compiler/GHC/Core/Reduction.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Core/TyCo/Compare.hs
- compiler/GHC/Core/TyCo/FVs.hs
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCo/Rep.hs-boot
- compiler/GHC/Core/TyCo/Subst.hs
- compiler/GHC/Core/TyCo/Tidy.hs
- compiler/GHC/Core/TyCon.hs

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/7e299449d425bff43ec85b7684928bf775aac32f...ff4a6c2ebdb2234862d778be1ba1babf929372e2

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