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Ben Gamari pushed to branch wip/T26053 at Glasgow Haskell Compiler / GHC

Commits:

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