GitLab

Rodrigo Mesquita pushed to branch wip/romes/26227 at Glasgow Haskell Compiler / GHC

Commits:

f707bab4

by Andreas Klebinger at 2025-07-12T14:56:16+01:00

Specialise: Improve specialisation by refactoring interestingDict

This MR addresses #26051, which concerns missed type-class specialisation.
The main payload of the MR is to completely refactor the key function
      `interestingDict` in GHC.Core.Opt.Specialise

The main change is that we now also look at the structure of the
dictionary we consider specializing on, rather than only the type.

See the big `Note [Interesting dictionary arguments]`

ca7a9d42

by Simon Peyton Jones at 2025-07-12T14:56:16+01:00

Treat tuple dictionaries uniformly; don't unbox them

See `Note [Do not unbox class dictionaries]` in DmdAnal.hs,
sep (DNB1).

This MR reverses the plan in #23398, which suggested a special case to
unbox tuple dictionaries in worker/wrapper.  But:

- This was the cause of a pile of complexity in the specialiser (#26158)

- Even with that complexity, specialision was still bad, very bad
  See https://gitlab.haskell.org/ghc/ghc/-/issues/19747#note_626297

And it's entirely unnecessary!  Specialision works fine without
unboxing tuple dictionaries.

be7296c9

by Andreas Klebinger at 2025-07-12T14:56:16+01:00

Remove complex special case from the type-class specialiser

There was a pretty tricky special case in Specialise which is no
longer necessary.
   * Historical Note [Floating dictionaries out of cases]
   * #26158
   * #19747 https://gitlab.haskell.org/ghc/ghc/-/issues/19747#note_626297

This MR removes it.  Hooray.

4acf3a86
by Ben Gamari at 2025-07-15T05:46:32-04:00
```
configure: bump version to 9.15
```

45efaf71

by Teo Camarasu at 2025-07-15T05:47:13-04:00

rts/nonmovingGC: remove n_free

We remove the nonmovingHeap.n_free variable.

We wanted this to track the length of nonmovingHeap.free.
But this isn't possible to do atomically.

When this isn't accurate we can get a segfault by going past the end of
the list.

Instead, we just count the length of the list when we grab it in
nonmovingPruneFreeSegment.

Resolves #26186

c635f164

by Ben Gamari at 2025-07-15T14:05:54-04:00

configure: Drop probing of ld.gold

As noted in #25716, `gold` has been dropped from binutils-2.44.

Fixes #25716.

Metric Increase:
    size_hello_artifact_gzip
    size_hello_unicode_gzip
    ghc_prim_so

637bb538

by Ben Gamari at 2025-07-15T14:05:55-04:00

testsuite/recomp015: Ignore stderr

This is necessary since ld.bfd complains
that we don't have a .note.GNU-stack section,
potentially resulting in an executable stack.

d3cd4ec8
by Wen Kokke at 2025-07-15T14:06:39-04:00
```
Fix documentation for heap profile ID
```
73082769
by Ben Gamari at 2025-07-15T16:56:38-04:00
```
Bump win32-tarballs to v0.9
```

3b63b254

by Ben Gamari at 2025-07-15T16:56:39-04:00

rts/LoadArchive: Handle null terminated string tables

As of `llvm-ar` now emits filename tables terminated with null
characters instead of the usual POSIX `/\n` sequence.

Fixes #26150.

195f6527

by Tamar Christina at 2025-07-15T16:56:39-04:00

rts: rename label so name doesn't conflict with param

63373b95
by Tamar Christina at 2025-07-15T16:56:39-04:00
```
rts: Handle API set symbol versioning conflicts
```

48e9aa3e

by Tamar Christina at 2025-07-15T16:56:39-04:00

rts: Mark API set symbols as HIDDEN and correct symbol type

959e827a

by Tamar Christina at 2025-07-15T16:56:39-04:00

rts: Implement WEAK EXTERNAL undef redirection by target symbol name

65f19293

by Ben Gamari at 2025-07-15T16:56:39-04:00

rts/LoadArchive: Handle string table entries terminated with /

llvm-ar appears to terminate string table entries with `/\n` [1]. This
matters in the case of thin archives, since the filename is used. In the
past this worked since `llvm-ar` would produce archives with "small"
filenames when possible. However, now it appears to always use the
string table.

[1] https://github.com/llvm/llvm-project/blob/bfb686bb5ba503e9386dc899e1ebbe2488e6a0a8/llvm/lib/Object/ArchiveWriter.cpp#L314

9cbb3ef5

by Ben Gamari at 2025-07-15T16:56:39-04:00

testsuite: Mark T12497 as fixed

Thanks to the LLVM toolchain update.

Closes #22694.

2854407e

by Ben Gamari at 2025-07-15T16:56:39-04:00

testsuite: Accept new output of T11223_link_order_a_b_2_fail on Windows

The archive member number changed due to the fact that llvm-ar now uses a
string table.

28439593

by Ben Gamari at 2025-07-15T16:56:39-04:00

rts/linker/PEi386: Implement IMAGE_REL_AMD64_SECREL

This appears to now be used by libc++ as distributed by msys2.

2b053755

by Tamar Christina at 2025-07-15T16:56:39-04:00

rts: Cleanup merge resolution residue in lookupSymbolInDLL_PEi386 and make safe without dependent

e8acd2e7

by Wen Kokke at 2025-07-16T08:37:04-04:00

Remove the `profile_id` parameter from various RTS functions.

Various RTS functions took a `profile_id` parameter, intended to be used to
distinguish parallel heap profile breakdowns (e.g., `-hT` and `-hi`). However,
this feature was never implemented and the `profile_id` parameter was set to 0
throughout the RTS. This commit removes the parameter but leaves the hardcoded
profile ID in the functions that emit the encoded eventlog events as to not
change the protocol.

The affected functions are `traceHeapProfBegin`, `postHeapProfBegin`,
`traceHeapProfSampleString`, `postHeapProfSampleString`,
`traceHeapProfSampleCostCentre`, and `postHeapProfSampleCostCentre`.

76d392a2
by Wen Kokke at 2025-07-16T08:37:04-04:00
```
Make `traceHeapProfBegin` an init event.
```

bbaa44a7

by Peng Fan at 2025-07-16T16:50:42-04:00

NCG/LA64: Support finer-grained DBAR hints

For LA664 and newer uarchs, they have made finer granularity hints
available:

    Bit4: ordering or completion (0: completion, 1: ordering)
    Bit3: barrier for previous read (0: true, 1: false)
    Bit2: barrier for previous write (0: true, 1: false)
    Bit1: barrier for succeeding read (0: true, 1: false)
    Bit0: barrier for succeeding write (0: true, 1: false)

And not affect the existing models because other hints are treated
as 'dbar 0' there.

7da86e16

by Andreas Klebinger at 2025-07-16T16:51:25-04:00

Disable -fprof-late-overloaded-calls for join points.

Currently GHC considers cost centres as destructive to
join contexts. Or in other words this is not considered valid:

    join f x = ...
    in
              ... -> scc<tick> jmp

This makes the functionality of `-fprof-late-overloaded-calls` not feasible
for join points in general. We used to try to work around this by putting the
ticks on the rhs of the join point rather than around the jump. However beyond
the loss of accuracy this was broken for recursive join points as we ended up
with something like:

    rec-join f x = scc<tick> ... jmp f x

Which similarly is not valid as the tick once again destroys the tail call.
One might think we could limit ourselves to non-recursive tail calls and do
something clever like:

  join f x = scc<tick> ...
  in ... jmp f x

And sometimes this works! But sometimes the full rhs would look something like:

  join g x = ....
  join f x = scc<tick> ... -> jmp g x

Which, would again no longer be valid. I believe in the long run we can make
cost centre ticks non-destructive to join points. Or we could keep track of
where we are/are not allowed to insert a cost centre. But in the short term I will
simply disable the annotation of join calls under this flag.

7ee22fd5

by ARATA Mizuki at 2025-07-17T06:05:30-04:00

x86 NCG: Better lowering for shuffleFloatX4# and shuffleDoubleX2#

The new implementation

* make use of specialized instructions like (V)UNPCK{L,H}{PS,PD}, and
* do not require -mavx.

Close #26096

Co-authored-by: sheaf <sam.derbyshire@gmail.com>

c6cd2da1

by Jappie Klooster at 2025-07-17T06:06:20-04:00

Update interact docs to explain about buffering

We need to tell the user to set to the
appropriate buffer format.
Otherwise, this function may get randomly stuck,
or just behave confusingly.

issue: https://gitlab.haskell.org/ghc/ghc/-/issues/26131

NB, I'm running this with cabal *NOT* ghci. ghci messes with buffering anyway.

```haskell
interaction :: String -> String
interaction "jappie" = "hi"
interaction "jakob" = "hello"
interaction x = "unkown input: " <> x

main :: IO ()
main = interact  interaction
```
so in my input (prefixed by `>`) I get:

```
> jappie
unkown input: jappie
```

we confirmed later this was due to lack of \n matching.
Anyway movnig on to more unexpected stuff:

```haskell
main :: IO ()
main = do
  interact  (concatMap interaction . lines)
```

get's stuck forever.
actually `^D` (ctrl+d) unstucks it and runs all input as expected.
for example you can get:
```
> sdfkds
> fakdsf
unkown input: sdfkdsunkown input: fakdsf
```

This program works!
```haskell
interaction :: String -> String
interaction "jappie" = "hi \n"
interaction "jakob" = "hello \n"
interaction x = "unkown input: " <> x <> "\n"

main :: IO ()
main = do
  interact  (concatMap interaction . lines)
```
the reason is that linebuffering is set for both in and output by default.
so lines eats the input lines, and all the \n postfixes make sure the buffer
is put out.

9fa590a6

by Zubin Duggal at 2025-07-17T06:07:03-04:00

fetch_gitlab: Ensure we copy users_guide.pdf and Haddock.pdf to the release docs directory

Fixes #24093

cc650b4b

by Andrew Lelechenko at 2025-07-17T12:30:24-04:00

Add Data.List.NonEmpty.mapMaybe

As per https://github.com/haskell/core-libraries-committee/issues/337

360fa82c

by Duncan Coutts at 2025-07-17T12:31:14-04:00

base: Deprecate GHC.Weak.Finalize.runFinalizerBatch

https://github.com/haskell/core-libraries-committee/issues/342

f4e8466c

by Alan Zimmerman at 2025-07-17T12:31:55-04:00

EPA: Update exact printing based on GHC 9.14 tests

As a result of migrating the GHC ghc-9.14 branch tests to
ghc-exactprint in
https://github.com/alanz/ghc-exactprint/tree/ghc-9.14, a couple of
discrepancies were picked up

- The opening paren for a DefaultDecl was printed in the wrong place
- The import declaration level specifiers were not printed.

This commit adds those fixes, and some tests for them.
The tests brought to light that the ImportDecl ppr instance had not
been updated for level specifiers, so it updates that too.

8b731e3c

by Matthew Pickering at 2025-07-21T13:36:43-04:00

level imports: Fix infinite loop with cyclic module imports

I didn't anticipate that downsweep would run before we checked for
cyclic imports. Therefore we need to use the reachability function which
handles cyclic graphs.

Fixes #26087

d751a9f1
by Pierre Thierry at 2025-07-21T13:37:28-04:00
```
Fix documentation about deriving from generics
```

f8d9d016

by Andrew Lelechenko at 2025-07-22T21:13:28-04:00

Fix issues with toRational for types capable to represent infinite and not-a-number values

This commit fixes all of the following pitfalls:

> toRational (read "Infinity" :: Double)
179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216 % 1
> toRational (read "NaN" :: Double)
269653970229347386159395778618353710042696546841345985910145121736599013708251444699062715983611304031680170819807090036488184653221624933739271145959211186566651840137298227914453329401869141179179624428127508653257226023513694322210869665811240855745025766026879447359920868907719574457253034494436336205824 % 1

> realToFrac (read "NaN" :: Double) -- With -O0
Infinity
> realToFrac (read "NaN" :: Double) -- With -O1
NaN

> realToFrac (read "NaN" :: Double) :: CDouble
Infinity
> realToFrac (read "NaN" :: CDouble) :: Double
Infinity

Implements https://github.com/haskell/core-libraries-committee/issues/338

5dabc718

by Zubin Duggal at 2025-07-22T21:14:10-04:00

haddock: Don't warn about missing link destinations for derived names.

Fixes #26114

9c3a0937

by Matthew Pickering at 2025-07-22T21:14:52-04:00

template haskell: use a precise condition when implicitly lifting

Implicit lifting corrects a level error by replacing references to `x`
with `$(lift x)`, therefore you can use a level `n` binding at level `n
+ 1`, if it can be lifted.

Therefore, we now have a precise check that the use level is 1 more than
the bind level.

Before this bug was not observable as you only had 0 and 1 contexts but
it is easily evident when using explicit level imports.

Fixes #26088

5144b22f

by Andreas Klebinger at 2025-07-22T21:15:34-04:00

Add since tag and more docs for do-clever-arg-eta-expansion

Fixes #26113

c865623b

by Andreas Klebinger at 2025-07-22T21:15:34-04:00

Add since tag for -fexpose-overloaded-unfoldings

Fixes #26112

49a44ab7
by Simon Hengel at 2025-07-23T17:59:55+07:00
```
Refactor GHC.Driver.Errors.printMessages
```

84711c39

by Simon Hengel at 2025-07-23T18:27:34+07:00

Respect `-fdiagnostics-as-json` for error messages from pre-processors

(fixes #25480)

d046b5ab

by Simon Hengel at 2025-07-24T06:12:05-04:00

Include the rendered message in -fdiagnostics-as-json output

This implements #26173.

d2b89603

by Ben Gamari at 2025-07-24T06:12:47-04:00

rts/Interpreter: Factor out ctoi tuple info tables into data

Instead of a massive case let's put this into data which we can reuse
elsewhere.

4bc78496

by Sebastian Graf at 2025-07-24T16:19:34-04:00

CprAnal: Detect recursive newtypes (#25944)

While `cprTransformDataConWork` handles recursive data con workers, it
did not detect the case when a newtype is responsible for the recursion.
This is now detected in the `Cast` case of `cprAnal`.

The same reproducer made it clear that `isRecDataCon` lacked congruent
handling for `AppTy` and `CastTy`, now fixed.

Furthermore, the new repro case T25944 triggered this bug via an
infinite loop in `cprFix`, caused by the infelicity in `isRecDataCon`.
While it should be much less likely to trigger such an infinite loop now
that `isRecDataCon` has been fixed, I made sure to abort the loop after
10 iterations and emitting a warning instead.

Fixes #25944.

0a583689

by Sylvain Henry at 2025-07-24T16:20:26-04:00

STM: don't create a transaction in the rhs of catchRetry# (#26028)

We don't need to create a transaction for the rhs of (catchRetry#)
because contrary to the lhs we don't need to abort it on retry. Moreover
it is particularly harmful if we have code such as (#26028):

  let cN = readTVar vN >> retry
      tree = c1 `orElse` (c2 `orElse` (c3 `orElse` ...))
  atomically tree

Because it will stack transactions for the rhss and the read-sets of all
the transactions will be iteratively merged in O(n^2) after the
execution of the most nested retry.

a49eca26

by Simon Peyton Jones at 2025-07-25T09:49:58+01:00

Renaming around predicate types

.. we were (as it turned out) abstracting over
type-class selectors in SPECIALISATION rules!

Wibble isEqPred

f80375dd

by Simon Peyton Jones at 2025-07-25T09:49:58+01:00

Refactor of Specialise.hs

This patch just tidies up `specHeader` a bit, removing one
of its many results, and adding some comments.

No change in behaviour.

Also add a few more `HasDebugCallStack` contexts.

1bd12371

by Simon Peyton Jones at 2025-07-25T09:49:58+01:00

Improve treatment of SPECIALISE pragmas -- again!

This MR does another major refactor of the way that SPECIALISE
pragmas work, to fix #26115, #26116, #26117.

* We now /always/ solve forall-constraints in an all-or-nothing way.
  See Note [Solving a Wanted forall-constraint] in GHC.Tc.Solver.Solve

  This means we might have unsolved quantified constraints, which need
  to be reported.  See `inert_insts` in `getUnsolvedInerts`.

* I refactored the short-cut solver for type classes to work by
  recursively calling the solver rather than by having a little baby
  solver that kept being not clever enough.
  See Note [Shortcut solving] in GHC.Tc.Solver.Dict

* I totally rewrote the desugaring of SPECIALISE pragmas, again.
  The new story is in Note [Desugaring new-form SPECIALISE pragmas]
  in GHC.HsToCore.Binds

  Both old-form and new-form SPECIALISE pragmas now route through the same
  function `dsSpec_help`.   The tricky function `decomposeRuleLhs` is now used only
  for user-written RULES, not for SPECIALISE pragmas.

* I improved `solveOneFromTheOther` to account for rewriter sets. Previously
  it would solve a non-rewritten dict from a rewritten one.  For equalities
  we were already dealing with this, in

Some incidental refactoring

* A small refactor: `ebv_tcvs` in `EvBindsBar` now has a list of coercions, rather
  than a set of tyvars.  We just delay taking the free vars.

* GHC.Core.FVs.exprFVs now returns /all/ free vars.
  Use `exprLocalFVs` for Local vars.
  Reason: I wanted another variant for /evidence/ variables.

* Ues `EvId` in preference to `EvVar`.  (Evidence variables are always Ids.)
  Rename `isEvVar` to `isEvId`.

* I moved `inert_safehask` out of `InertCans` and into `InertSet` where it
  more properly belongs.

Compiler-perf changes:
  * There was a palpable bug (#26117) which this MR fixes in
    newWantedEvVar, which bypassed all the subtle overlapping-Given
    and shortcutting logic.  (See the new `newWantedEvVar`.)  Fixing this
    but leads to extra dictionary bindings; they are optimised away quickly
    but they made CoOpt_Read allocate 3.6% more.

  * Hpapily T15164 improves.

  * The net compiler-allocation change is 0.0%

Metric Decrease:
    T15164
Metric Increase:
    CoOpt_Read
    T12425

953fd8f1

by Simon Peyton Jones at 2025-07-25T09:49:58+01:00

Solve forall-constraints immediately, or not at all

This MR refactors the constraint solver to solve forall-constraints immediately,
rather than emitting an implication constraint to be solved later.

The most immediate motivation was that when solving quantified constraints
in SPECIALISE pragmas, we really really don't want to leave behind half-
solved implications.  Also it's in tune with the approach of the new
short-cut solver, which recursively invokes the solver.

It /also/ saves quite a bit of plumbing; e.g

  - The `wl_implics` field of `WorkList` is gone,

  - The types of `solveSimpleWanteds` and friends are simplified.

  - An EvFun contains binding, rather than an EvBindsVar ref-cell that
    will in the future contain bindings.  That makes `evVarsOfTerm`
    simpler.  Much nicer.

It also improves error messages a bit.

All described in Note [Solving a Wanted forall-constraint] in
GHC.Tc.Solver.Solve.

One tiresome point: in the tricky case of `inferConstraintsCoerceBased`
we make a forall-constraint.  This we /do/ want to partially solve, so
we can infer a suitable context. (I'd be quite happy to force the user to
write a context, bt I don't want to change behavior.)  So we want to generate
an /implication/ constraint in `emitPredSpecConstraints` rather than a
/forall-constraint/ as we were doing before.  Discussed in (WFA3) of
the above Note.

Incidental refactoring

* `GHC.Tc.Deriv.Infer.inferConstraints` was consulting the state monad for
  the DerivEnv that the caller had just consulted.  Nicer to pass it as an
  argument I think, so I have done that.  No change in behaviour.

6921ab42

by Simon Peyton Jones at 2025-07-25T09:49:58+01:00

Remove duplicated code in Ast.hs for evTermFreeVars

This is just a tidy up.

1165f587
by Simon Peyton Jones at 2025-07-25T09:49:58+01:00
```
Small tc-tracing changes only
```

0776ffe0

by Simon Hengel at 2025-07-26T04:54:20-04:00

Respect `-fdiagnostics-as-json` for core diagnostics (see #24113)

cc1116e0
by Andrew Lelechenko at 2025-07-26T04:55:01-04:00
```
docs: add since pragma to Data.List.NonEmpty.mapMaybe
```

ee2dc248

by Simon Hengel at 2025-07-31T06:25:35-04:00

Update comments on `OptKind` to reflect the code reality

b029633a

by Wen Kokke at 2025-07-31T06:26:21-04:00

rts: Disable --eventlog-flush-interval unless compiled with -threaded.

This commit fixes issue #26222:
Using --eventlog-flush-interval with the non-threaded RTS leads to eventlog corruption.
https://gitlab.haskell.org/ghc/ghc/-/issues/26222

This commit makes three changes when code is compiled against the non-threaded RTS:

1. It disables the --eventlog-flush-interval flag.
2. It disables the documentation for the --eventlog-flush-interval flag.
3. It disables the relevant state from RtsConfig and code from Timer.
4. It updates the entry for --eventlog-flush-interval in the users guide.

31159f1d

by Wen Kokke at 2025-07-31T06:26:21-04:00

rts: Split T20006 into tests with and without -threaded

618687ef

by Simon Hengel at 2025-07-31T06:27:03-04:00

docs/users_guide/win32-dlls.rst: Remove references to `readline`

083e40f1

by Rodrigo Mesquita at 2025-08-01T04:38:23-04:00

debugger: Uniquely identify breakpoints by internal id

Since b85b11994e0130ff2401dd4bbdf52330e0bcf776 (support inlining
breakpoints), a breakpoint has been identified at runtime by *two* pairs
of <module,index>.

- The first, aka a 'BreakpointId', uniquely identifies a breakpoint in
  the source of a module by using the Tick index. A Tick index can index
  into ModBreaks.modBreaks_xxx to fetch source-level information about
  where that tick originated.

    - When a user specifies e.g. a line breakpoint using :break, we'll reverse
      engineer what a Tick index for that line
    - We update the `BreakArray` of that module (got from the
      LoaderState) at that tick index to `breakOn`.
    - A BCO we can stop at is headed by a BRK_FUN instruction. This
      instruction stores in an operand the `tick index` it is associated
      to. We look it up in the associated `BreakArray` (also an operand)
      and check wheter it was set to `breakOn`.

- The second, aka the `ibi_info_mod` + `ibi_info_ix` of the
  `InternalBreakpointId`, uniquely index into the `imodBreaks_breakInfo`
  -- the information we gathered during code generation about the
  existing breakpoint *ocurrences*.

  - Note that with optimisation there may be many occurrences of the
    same source-tick-breakpoint across different modules. The
    `ibi_info_ix` is unique per occurrence, but the `bi_tick_ix` may be
    shared. See Note [Breakpoint identifiers] about this.

  - Note that besides the tick ids, info ids are also stored in
    `BRK_FUN` so the break handler can refer to the associated
    `CgBreakInfo`.

In light of that, the driving changes come from the desire to have the
info_id uniquely identify the breakpoint at runtime, and the source tick
id being derived from it:

- An InternalBreakpointId should uniquely identify a breakpoint just
  from the code-generation identifiers of `ibi_info_ix` and `ibi_info_mod`.
  So we drop `ibi_tick_mod` and `ibi_tick_ix`.
- A BRK_FUN instruction need only record the "internal breakpoint id",
  not the tick-level id.
  So we drop the tick mod and tick index operands.
- A BreakArray should be indexed by InternalBreakpointId rather than
  BreakpointId

That means we need to do some more work when setting a breakpoint.
Specifically, we need to figure out the internal ids (occurrences of a
breakpoint) from the source-level BreakpointId we want to set the
breakpoint at (recall :break refers to breaks at the source level).

Besides this change being an improvement to the handling of breakpoints
(it's clearer to have a single unique identifier than two competing
ones), it unlocks the possibility of generating "internal" breakpoints
during Cg (needed for #26042).
It should also be easier to introduce multi-threaded-aware `BreakArrays`
following this change (needed for #26064).

Se also the new Note [ModBreaks vs InternalModBreaks]

On i386-linux:

-------------------------
Metric Decrease:
    interpreter_steplocal
-------------------------

bf03bbaa

by Simon Hengel at 2025-08-01T04:39:05-04:00

Don't use MCDiagnostic for `ghcExit`

This changes the error message of `ghcExit` from

```
<no location info>: error:
Compilation had errors

```
to
```

Compilation had errors

```

a889ec75

by Simon Hengel at 2025-08-01T04:39:05-04:00

Respect `-fdiagnostics-as-json` for driver diagnostics (see #24113)

3e6d49f7