[Git][ghc/ghc][wip/release-fixes] 138 commits: Note mutability of array and address access primops

Ben Gamari (@bgamari) gitlab at gitlab.haskell.org
Mon Apr 15 15:34:15 UTC 2024



Ben Gamari pushed to branch wip/release-fixes at Glasgow Haskell Compiler / GHC


Commits:
77171cd1 by Ben Orchard at 2024-03-14T09:00:40-04:00
Note mutability of array and address access primops

Without an understanding of immutable vs. mutable memory, the index
primop family have a potentially non-intuitive type signature:

    indexOffAddr :: Addr# -> Int# -> a
    readOffAddr  :: Addr# -> Int# -> State# d -> (# State# d, a #)

indexOffAddr# might seem like a free generality improvement, which it
certainly is not!

This change adds a brief note on mutability expectations for most
index/read/write access primops.

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7da7f8f6 by Alan Zimmerman at 2024-03-14T09:01:15-04:00
EPA: Fix regression discarding comments in contexts

Closes #24533

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73be65ab by Fendor at 2024-03-19T01:42:53-04:00
Fix sharing of 'IfaceTyConInfo' during core to iface type translation

During heap analysis, we noticed that during generation of
'mi_extra_decls' we have lots of duplicates for the instances:

* `IfaceTyConInfo NotPromoted IfaceNormalTyCon`
* `IfaceTyConInfo IsPromoted IfaceNormalTyCon`

which should be shared instead of duplicated. This duplication increased
the number of live bytes by around 200MB while loading the agda codebase
into GHCi.

These instances are created during `CoreToIface` translation, in
particular `toIfaceTyCon`.

The generated core looks like:

    toIfaceTyCon
      = \ tc_sjJw ->
          case $wtoIfaceTyCon tc_sjJw of
          { (# ww_sjJz, ww1_sjNL, ww2_sjNM #) ->
          IfaceTyCon ww_sjJz (IfaceTyConInfo ww1_sjNL ww2_sjNM)
          }

whichs removes causes the sharing to work propery.

Adding explicit sharing, with NOINLINE annotations, changes the core to:

    toIfaceTyCon
      = \ tc_sjJq ->
          case $wtoIfaceTyCon tc_sjJq of { (# ww_sjNB, ww1_sjNC #) ->
          IfaceTyCon ww_sjNB ww1_sjNC
          }

which looks much more like sharing is happening.
We confirmed via ghc-debug that all duplications were eliminated and the
number of live bytes are noticeably reduced.

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bd8209eb by Alan Zimmerman at 2024-03-19T01:43:28-04:00
EPA: Address more 9.10.1-alpha1 regressions from recent changes

Closes #24533
Hopefully for good this time

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31bf85ee by Fendor at 2024-03-19T14:48:08-04:00
Escape multiple arguments in the settings file

Uses responseFile syntax.

The issue arises when GHC is installed on windows into a location that
has a space, for example the user name is 'Fake User'.
The $topdir will also contain a space, consequentially.
When we resolve the top dir in the string `-I$topdir/mingw/include`,
then `words` will turn this single argument into `-I/C/Users/Fake` and
`User/.../mingw/include` which trips up the flag argument parser of
various tools such as gcc or clang.
We avoid this by escaping the $topdir before replacing it in
`initSettngs`.
Additionally, we allow to escape spaces and quotation marks for
arguments in `settings` file.

Add regression test case to count the number of options after variable
expansion and argument escaping took place.
Additionally, we check that escaped spaces and double quotation marks are
correctly parsed.

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f45f700e by Matthew Pickering at 2024-03-19T14:48:44-04:00
Read global package database from settings file

Before this patch, the global package database was always assumed to be
in libdir </> package.conf.d.

This causes issues in GHC's build system because there are sometimes
situations where the package database you need to use is not located in
the same place as the settings file.

* The stage1 compiler needs to use stage1 libraries, so we should set
  "Global Package DB" for the stage1 compiler to the stage1 package
  database.
* Stage 2 cross compilers need to use stage2 libraries, so likewise, we
  should set the package database path to `_build/stage2/lib/`

* The normal situation is where the stage2 compiler uses stage1
  libraries. Then everything lines up.

* When installing we have rearranged everything so that the settings
  file and package database line up properly, so then everything should
  continue to work as before. In this case we set the relative package
  db path to `package.conf.d`, so it resolves the same as before.

* ghc-pkg needs to be modified as well to look in the settings file fo
  the package database rather than assuming the global package database
  location relative to the lib folder.

* Cabal/cabal-install will work correctly because they query the global
  package database using `--print-global-package-db`.

A reasonable question is why not generate the "right" settings files in
the right places in GHC's build system. In order to do this you would
need to engineer wrappers for all executables to point to a specific
libdir. There are also situations where the same package db is used by
two different compilers with two different settings files (think stage2
cross compiler and stage3 compiler).

In short, this 10 line patch allows for some reasonable simplifications
in Hadrian at very little cost to anything else.

Fixes #24502

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4c8f1794 by Matthew Pickering at 2024-03-19T14:48:44-04:00
hadrian: Remove stage1 testsuite wrappers logic

Now instead of producing wrappers which pass the global package database
argument to ghc and ghc-pkg, we write the location of the correct
package database into the settings file so you can just use the intree
compiler directly.

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da0d8ba5 by Matthew Craven at 2024-03-19T14:49:20-04:00
Remove unused ghc-internal module "GHC.Internal.Constants"

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b56d2761 by Matthew Craven at 2024-03-19T14:49:20-04:00
CorePrep: Rework lowering of BigNat# literals

Don't use bigNatFromWord#, because that's terrible:
 * We shouldn't have to traverse a linked list at run-time
   to build a BigNat# literal. That's just silly!
 * The static List object we have to create is much larger
   than the actual BigNat#'s contents, bloating code size.
 * We have to read the corresponding interface file,
   which causes un-tracked implicit dependencies. (#23942)

Instead, encode them into the appropriate platform-dependent
sequence of bytes, and generate code that copies these bytes
at run-time from an Addr# literal into a new ByteArray#.
A ByteArray# literal would be the correct thing to generate,
but these are not yet supported; see also #17747.

Somewhat surprisingly, this change results in a slight
reduction in compiler allocations, averaging around 0.5%
on ghc's compiler performance tests, including when compiling
programs that contain no bignum literals to begin with.
The specific cause of this has not been investigated.

Since this lowering no longer reads the interface file for
GHC.Num.BigNat, the reasoning in Note [Depend on GHC.Num.Integer]
is obsoleted.  But the story of un-tracked built-in dependencies
remains complex, and Note [Tracking dependencies on primitives]
now exists to explain this complexity.

Additionally, many empty imports have been modified to refer to
this new note and comply with its guidance.  Several empty imports
necessary for other reasons have also been given brief explanations.

Metric Decrease:
    MultiLayerModulesTH_OneShot

- - - - -
349ea330 by Fendor at 2024-03-19T14:50:00-04:00
Eliminate thunk in 'IfaceTyCon'

Heap analysis showed that `IfaceTyCon` retains a thunk to
`IfaceTyConInfo`, defeating the sharing of the most common instances of
`IfaceTyConInfo`.
We make sure the indirection is removed by adding bang patterns to
`IfaceTyCon`.

Experimental results on the agda code base, where the `mi_extra_decls`
were read from disk:

Before this change, we observe around 8654045 instances of:

`IfaceTyCon[Name,THUNK_1_0]`

But these thunks almost exclusively point to a shared value!

Forcing the thunk a little bit more, leads to `ghc-debug` reporting:

`IfaceTyCon[Name:Name,IfaceTyConInfo]`

and a noticeable reduction of live bytes (on agda ~10%).

- - - - -
594bee0b by Krzysztof Gogolewski at 2024-03-19T14:50:36-04:00
Minor misc cleanups

- GHC.HsToCore.Foreign.JavaScript: remove dropRuntimeRepArgs;
  boxed tuples don't take RuntimeRep args
- GHC.HsToCore.Foreign.Call: avoid partial pattern matching
- GHC.Stg.Unarise: strengthen the assertion; we can assert that
  non-rubbish literals are unary rather than just non-void
- GHC.Tc.Gen.HsType: make sure the fsLit "literal" rule fires
- users_guide/using-warnings.rst: remove -Wforall-identifier,
  now deprecated and does nothing
- users_guide/using.rst: fix formatting
- andy_cherry/test.T: remove expect_broken_for(23272...), 23272 is fixed

The rest are simple cleanups.

- - - - -
cf55a54b by Ben Gamari at 2024-03-19T14:51:12-04:00
mk/relpath: Fix quoting

Previously there were two instances in this script which lacked proper
quoting. This resulted in `relpath` invocations in the binary
distribution Makefile producing incorrect results on Windows, leading to
confusing failures from `sed` and the production of empty package
registrations.

Fixes #24538.

- - - - -
5ff88389 by Bryan Richter at 2024-03-19T14:51:48-04:00
testsuite: Disable T21336a on wasm

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60023351 by Ben Gamari at 2024-03-19T22:33:10-04:00
hadrian/bindist: Eliminate extraneous `dirname` invocation

Previously we would call `dirname` twice per installed library file.
We now instead reuse this result. This helps appreciably on Windows, where
processes are quite expensive.

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616ac300 by Ben Gamari at 2024-03-19T22:33:10-04:00
hadrian: Package mingw toolchain in expected location

This fixes #24525, a regression due to 41cbaf44a6ab5eb9fa676d65d32df8377898dc89.
Specifically, GHC expects to find the mingw32 toolchain in the binary distribution
root. However, after this patch it was packaged in the `lib/` directory.

- - - - -
de9daade by Ben Gamari at 2024-03-19T22:33:11-04:00
gitlab/rel_eng: More upload.sh tweaks

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1dfe12db by Ben Gamari at 2024-03-19T22:33:11-04:00
rel_eng: Drop dead prepare_docs codepath

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dd2d748b by Ben Gamari at 2024-03-19T22:33:11-04:00
rel_env/recompress_all: unxz before recompressing

Previously we would rather compress the xz *again*, before in addition
compressing it with the desired scheme.

Fixes #24545.

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9d936c57 by Ben Gamari at 2024-03-19T22:33:11-04:00
mk-ghcup-metadata: Fix directory of testsuite tarball

As reported in #24546, the `dlTest` artifact should be extracted into
the `testsuite` directory.

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6d398066 by Ben Gamari at 2024-03-19T22:33:11-04:00
ghcup-metadata: Don't populate dlOutput unless necessary

ghcup can apparently infer the output name of an artifact from its URL.
Consequently, we should only include the `dlOutput` field when it would
differ from the filename of `dlUri`.

Fixes #24547.

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576f8b7e by Zubin Duggal at 2024-03-19T22:33:46-04:00
Revert "Apply shellcheck suggestion to SUBST_TOOLDIR"

This reverts commit c82770f57977a2b5add6e1378f234f8dd6153392.

The shellcheck suggestion is spurious and results in SUBST_TOOLDIR being a
no-op. `set` sets positional arguments for bash, but we want to set the variable
given as the first autoconf argument.

Fixes #24542

Metric decreases because the paths in the settings file are now shorter,
so we allocate less when we read the settings file.

-------------------------
Metric Decrease:
    T12425
    T13035
    T9198
-------------------------

- - - - -
cdfe6e01 by Fendor at 2024-03-19T22:34:22-04:00
Compact serialisation of IfaceAppArgs

In #24563, we identified that IfaceAppArgs serialisation tags each
cons cell element with a discriminator byte. These bytes add up
quickly, blowing up interface files considerably when
'-fwrite-if-simplified-core' is enabled.

We compact the serialisation by writing out the length of
'IfaceAppArgs', followed by serialising the elements directly without
any discriminator byte.

This improvement can decrease the size of some interface files by up
to 35%.

- - - - -
97a2bb1c by Simon Peyton Jones at 2024-03-20T17:11:29+00:00
Expand untyped splices in tcPolyExprCheck

Fixes #24559

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5f275176 by Alan Zimmerman at 2024-03-20T22:44:12-04:00
EPA: Clean up Exactprint helper functions a bit

- Introduce a helper lens to compose on `EpAnn a` vs `a` versions
- Rename some prime versions of functions back to non-prime
  They were renamed during the rework

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da2a10ce by Vladislav Zavialov at 2024-03-20T22:44:48-04:00
Type operators in promoteOccName (#24570)

Type operators differ from term operators in that they are lexically
classified as (type) constructors, not as (type) variables.

Prior to this change, promoteOccName did not account for this
difference, causing a scoping issue that affected RequiredTypeArguments.

  type (!@#) = Bool
  f = idee (!@#)      -- Not in scope: ‘!@#’  (BUG)

Now we have a special case in promoteOccName to account for this.

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247fc0fa by Preetham Gujjula at 2024-03-21T10:19:18-04:00
docs: Remove mention of non-existent Ord instance for Complex

The documentation for Data.Complex says that the Ord instance for Complex Float
is deficient, but there is no Ord instance for Complex a. The Eq instance for
Complex Float is similarly deficient, so we use that as an example instead.

- - - - -
6fafc51e by Andrei Borzenkov at 2024-03-21T10:19:54-04:00
Fix TH handling in `pat_to_type_pat` function (#24571)

There was missing case for `SplicePat` in `pat_to_type_at` function,
hence patterns with splicing that checked against `forall->` doesn't work
properly because they fall into the "illegal pattern" case.

Code example that is now accepted:

  g :: forall a -> ()
  g $([p| a |]) = ()

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52072f8e by Sylvain Henry at 2024-03-21T21:01:59-04:00
Type-check default declarations before deriving clauses (#24566)

See added Note and #24566. Default declarations must be type-checked
before deriving clauses.

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7dfdf3d9 by Sylvain Henry at 2024-03-21T21:02:40-04:00
Lexer: small perf changes

- Use unsafeChr because we know our values to be valid
- Remove some unnecessary use of `ord` (return Word8 values directly)

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864922ef by Sylvain Henry at 2024-03-21T21:02:40-04:00
JS: fix some comments

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3e0b2b1f by Sebastian Graf at 2024-03-21T21:03:16-04:00
Simplifier: Re-do dependency analysis in abstractFloats (#24551)

In #24551, we abstracted a string literal binding over a type variable,
triggering a CoreLint error when that binding floated to top-level.

The solution implemented in this patch fixes this by re-doing dependency
analysis on a simplified recursive let binding that is about to be type
abstracted, in order to find the minimal set of type variables to abstract over.
See wrinkle (AB5) of Note [Floating and type abstraction] for more details.

Fixes #24551

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8a8ac65a by Matthew Craven at 2024-03-23T00:20:52-04:00
Improve toInteger @Word32 on 64-bit platforms

On 64-bit platforms, every Word32 fits in an Int, so we can
convert to Int# without having to perform the overflow check
integerFromWord# uses internally.

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0c48f2b9 by Apoorv Ingle at 2024-03-23T00:21:28-04:00
Fix for #24552 (see testcase T24552)

Fixes for a bug in desugaring pattern synonyms matches, introduced
while working on  on expanding `do`-blocks in #18324

The `matchWrapper` unecessarily (and incorrectly) filtered out the
default wild patterns in a match. Now the wild pattern alternative is
simply ignored by the pm check as its origin is `Generated`.
The current code now matches the expected semantics according to the language spec.

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b72705e9 by Simon Peyton Jones at 2024-03-23T00:22:04-04:00
Print more info about kinds in error messages

This fixes #24553, where GHC unhelpfully said

  error: [GHC-83865]
    • Expected kind ‘* -> * -> *’, but ‘Foo’ has kind ‘* -> * -> *’

See Note [Showing invisible bits of types in error messages]

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8f7cfc7e by Tristan Cacqueray at 2024-03-23T00:22:44-04:00
docs: remove the don't use float hint

This hint is outdated, ``Complex Float`` are now specialised,
and the heap space suggestion needs more nuance so it should
be explained in the unboxed/storable array documentation.

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5bd8ed53 by Andreas Klebinger at 2024-03-23T16:18:33-04:00
NCG: Fix a bug in jump shortcutting.

When checking if a jump has more than one destination account for the
possibility of some jumps not being representable by a BlockId.

We do so by having isJumpishInstr return a `Maybe BlockId` where Nothing
represents non-BlockId jump destinations.

Fixes #24507

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8d67f247 by Ben Gamari at 2024-03-23T16:19:09-04:00
docs: Drop old release notes, add for 9.12.1

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7db8c992 by Cheng Shao at 2024-03-25T13:45:46-04:00
rts: fix clang compilation on aarch64

This patch fixes function prototypes in ARMOutlineAtomicsSymbols.h
which causes "error: address argument to atomic operation must be a
pointer to _Atomic type" when compiling with clang on aarch64.

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237194ce by Sylvain Henry at 2024-03-25T13:46:27-04:00
Lexer: fix imports for Alex 3.5.1 (#24583)

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810660b7 by Cheng Shao at 2024-03-25T22:19:16-04:00
libffi-tarballs: bump libffi-tarballs submodule to libffi 3.4.6

This commit bumps the libffi-tarballs submodule to libffi 3.4.6, which
includes numerous upstream libffi fixes, especially
https://github.com/libffi/libffi/issues/760.

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d2ba41e8 by Alan Zimmerman at 2024-03-25T22:19:51-04:00
EPA: do not duplicate comments in signature RHS

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32a8103f by Rodrigo Mesquita at 2024-03-26T21:16:12-04:00
configure: Use LDFLAGS when trying linkers

A user may configure `LDFLAGS` but not `LD`. When choosing a linker, we
will prefer `ldd`, then `ld.gold`, then `ld.bfd` -- however, we have to
check for a working linker. If either of these fail, we try the next in
line.

However, we were not considering the `$LDFLAGS` when checking if these
linkers worked. So we would pick a linker that does not support the
current $LDFLAGS and fail further down the line when we used that linker
with those flags.

Fixes #24565, where `LDFLAGS=-Wl,-z,pack-relative-relocs` is not
supported by `ld.gold` but that was being picked still.

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bf65a7c3 by Rodrigo Mesquita at 2024-03-26T21:16:48-04:00
bindist: Clean xattrs of bin and lib at configure time

For issue #21506, we started cleaning the extended attributes of
binaries and libraries from the bindist *after* they were installed to
workaround notarisation (#17418), as part of `make install`.

However, the `ghc-toolchain` binary that is now shipped with the bindist
must be run at `./configure` time. Since we only cleaned the xattributes
of the binaries and libs after they were installed, in some situations
users would be unable to run `ghc-toolchain` from the bindist, failing
at configure time (#24554).

In this commit we move the xattr cleaning logic to the configure script.

Fixes #24554

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cfeb70d3 by Rodrigo Mesquita at 2024-03-26T21:17:24-04:00
Revert "NCG: Fix a bug in jump shortcutting."

This reverts commit 5bd8ed53dcefe10b72acb5729789e19ceb22df66.

Fixes #24586

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13223f6d by Serge S. Gulin at 2024-03-27T07:28:51-04:00
JS: `h$rts_isProfiled` is removed from `profiling` and left its version at
`rts/js/config.js`

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0acfe391 by Alan Zimmerman at 2024-03-27T07:29:27-04:00
EPA: Do not extend declaration range for trailine zero len semi

The lexer inserts virtual semicolons having zero width.
Do not use them to extend the list span of items in a list.

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cd0fb82f by Alan Zimmerman at 2024-03-27T19:33:08+00:00
EPA: Fix FamDecl range

The span was incorrect if opt_datafam_kind_sig was empty

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f8f384a8 by Ben Gamari at 2024-03-29T01:23:03-04:00
Fix type of _get_osfhandle foreign import

Fixes #24601.

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00d3ecf0 by Alan Zimmerman at 2024-03-29T12:19:10+00:00
EPA: Extend StringLiteral range to include trailing commas

This goes slightly against the exact printing philosophy where
trailing decorations should be in an annotation, but the
practicalities of adding it to the WarningTxt environment, and the
problems caused by deviating do not make a more principles approach
worthwhile.

- - - - -
efab3649 by brandon s allbery kf8nh at 2024-03-31T20:04:01-04:00
clarify Note [Preproccesing invocations]

- - - - -
c8a4c050 by Ben Gamari at 2024-04-02T12:50:35-04:00
rts: Fix TSAN_ENABLED CPP guard

This should be `#if defined(TSAN_ENABLED)`, not `#if TSAN_ENABLED`,
lest we suffer warnings.

- - - - -
e91dad93 by Cheng Shao at 2024-04-02T12:50:35-04:00
rts: fix errors when compiling with TSAN

This commit fixes rts compilation errors when compiling with TSAN:

- xxx_FENCE macros are redefined and trigger CPP warnings.
- Use SIZEOF_W. WORD_SIZE_IN_BITS is provided by MachDeps.h which
  Cmm.h doesn't include by default.

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a9ab9455 by Cheng Shao at 2024-04-02T12:50:35-04:00
rts: fix clang-specific errors when compiling with TSAN

This commit fixes clang-specific rts compilation errors when compiling
with TSAN:

- clang doesn't have -Wtsan flag
- Fix prototype of ghc_tsan_* helper functions
- __tsan_atomic_* functions aren't clang built-ins and
  sanitizer/tsan_interface_atomic.h needs to be included
- On macOS, TSAN runtime library is
  libclang_rt.tsan_osx_dynamic.dylib, not libtsan. -fsanitize-thread
  as a link-time flag will take care of linking the TSAN runtime
  library anyway so remove tsan as an rts extra library

- - - - -
865bd717 by Cheng Shao at 2024-04-02T12:50:35-04:00
compiler: fix github link to __tsan_memory_order in a comment

- - - - -
07cb627c by Cheng Shao at 2024-04-02T12:50:35-04:00
ci: improve TSAN CI jobs

- Run TSAN jobs with +thread_sanitizer_cmm which enables Cmm
  instrumentation as well.
- Run TSAN jobs in deb12 which ships gcc-12, a reasonably recent gcc
  that @bgamari confirms he's using in #GHC:matrix.org. Ideally we
  should be using latest clang release for latest improvements in
  sanitizers, though that's left as future work.
- Mark TSAN jobs as manual+allow_failure in validate pipelines. The
  purpose is to demonstrate that we have indeed at least fixed
  building of TSAN mode in CI without blocking the patch to land, and
  once merged other people can begin playing with TSAN using their own
  dev setups and feature branches.

- - - - -
a1c18c7b by Andrei Borzenkov at 2024-04-02T12:51:11-04:00
Merge tc_infer_hs_type and tc_hs_type into one function using ExpType philosophy (#24299, #23639)

This patch implements refactoring which is a prerequisite to
updating kind checking of type patterns. This is a huge simplification
of the main worker that checks kind of HsType.

It also fixes the issues caused by previous code duplication, e.g.
that we didn't add module finalizers from splices in inference mode.

- - - - -
817e8936 by Rodrigo Mesquita at 2024-04-02T20:13:05-04:00
th: Hide the Language.Haskell.TH.Lib.Internal module from haddock

Fixes #24562

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b36ee57b by Sylvain Henry at 2024-04-02T20:13:46-04:00
JS: reenable h$appendToHsString optimization (#24495)

The optimization introducing h$appendToHsString wasn't kicking in
anymore (while it did in 9.8.1) because of the changes introduced in #23270 (7e0c8b3bab30).
This patch reenables the optimization by matching on case-expression, as
done in Cmm for unpackCString# standard thunks.

The test is also T24495 added in the next commits (two commits for ease
of backporting to 9.8).

- - - - -
527616e9 by Sylvain Henry at 2024-04-02T20:13:46-04:00
JS: fix h$appendToHsString implementation (#24495)

h$appendToHsString needs to wrap its argument in an updatable thunk
to behave like unpackAppendCString#. Otherwise if a SingleEntry thunk is
passed, it is stored as-is in a CONS cell, making the resulting list
impossible to deepseq (forcing the thunk doesn't update the contents of
the CONS cell)!

The added test checks that the optimization kicks in and that
h$appendToHsString works as intended.

Fix #24495

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faa30b41 by Simon Peyton Jones at 2024-04-02T20:14:22-04:00
Deal with duplicate tyvars in type declarations

GHC was outright crashing before this fix: #24604

- - - - -
e0b0c717 by Simon Peyton Jones at 2024-04-02T20:14:58-04:00
Try using MCoercion in exprIsConApp_maybe

This is just a simple refactor that makes exprIsConApp_maybe
a little bit more direct, simple, and efficient.

Metrics: compile_time/bytes allocated
    geo. mean                                          -0.1%
    minimum                                            -2.0%
    maximum                                            -0.0%

Not a big gain, but worthwhile given that the code is, if anything,
easier to grok.

- - - - -
15f4d867 by Duncan Coutts at 2024-04-03T01:27:17-04:00
Initial ./configure support for selecting I/O managers

In this patch we just define new CPP vars, but don't yet use them
or replace the existing approach. That will follow.

The intention here is that every I/O manager can be enabled/disabled at
GHC build time (subject to some constraints). More than one I/O manager
can be enabled to be built. At least one I/O manager supporting the
non-threaded RTS must be enabled as well as at least one supporting the
non-threaded RTS. The I/O managers enabled here will become the choices
available at runtime at RTS startup (in later patches). The choice can
be made with RTS flags. There are separate sets of choices for the
threaded and non-threaded RTS ways, because most I/O managers are
specific to these ways. Furthermore we must establish a default I/O
manager for the threaded and non-threaded RTS.

Most I/O managers are platform-specific so there are checks to ensure
each one can be enabled on the platform. Such checks are also where (in
future) any system dependencies (e.g. libraries) can be checked.

The output is a set of CPP flags (in the mk/config.h file), with one
flag per named I/O manager:
* IOMGR_BUILD_<name>                : which ones should be built (some)
* IOMGR_DEFAULT_NON_THREADED_<name> : which one is default (exactly one)
* IOMGR_DEFAULT_THREADED_<name>     : which one is default (exactly one)

and a set of derived flags in IOManager.h

* IOMGR_ENABLED_<name>              : enabled for the current RTS way

Note that IOMGR_BUILD_<name> just says that an I/O manager will be
built for _some_ RTS way (i.e. threaded or non-threaded). The derived
flags IOMGR_ENABLED_<name> in IOManager.h say if each I/O manager is
enabled in the "current" RTS way. These are the ones that can be used
for conditional compilation of the I/O manager code.

Co-authored-by: Pi Delport <pi at well-typed.com>

- - - - -
85b0f87a by Duncan Coutts at 2024-04-03T01:27:17-04:00
Change the handling of the RTS flag --io-manager=

Now instead of it being just used on Windows to select between the WinIO
vs the MIO or Win32-legacy I/O managers, it is now used on all platforms
for selecting the I/O manager to use.

Right now it remains the case that there is only an actual choice on
Windows, but that will change later.

Document the --io-manager flag in the user guide.

This change is also reflected in the RTS flags types in the base
library. Deprecate the export of IoSubSystem from GHC.RTS.Flags with a
message to import it from GHC.IO.Subsystem.

The way the 'IoSubSystem' is detected also changes. Instead of looking
at the RTS flag, there is now a C bool global var in the RTS which gets
set on startup when the I/O manager is selected. This bool var says
whether the selected I/O manager classifies as "native" on Windows,
which in practice means the WinIO I/O manager has been selected.

Similarly, the is_io_mng_native_p RTS helper function is re-implemented
in terms of the selected I/O manager, rather than based on the RTS
flags.

We do however remove the ./configure --native-io-manager flag because
we're bringing the WinIO/MIO/Win32-legacy choice under the new general
scheme for selecting I/O managers, and that new scheme involves no
./configure time user choices, just runtime RTS flag choices.

- - - - -
1a8f020f by Duncan Coutts at 2024-04-03T01:27:17-04:00
Convert {init,stop,exit}IOManager to switch style

Rather than ad-hoc cpp conitionals on THREADED_RTS and mingw32_HOST_OS,
we use a style where we switch on the I/O manager impl, with cases for
each I/O manager impl.

- - - - -
a5bad3d2 by Duncan Coutts at 2024-04-03T01:27:17-04:00
Split up the CapIOManager content by I/O manager

Using the new IOMGR_ENABLED_<name> CPP defines.

- - - - -
1d36e609 by Duncan Coutts at 2024-04-03T01:27:17-04:00
Convert initIOManagerAfterFork and wakeupIOManager to switch style

- - - - -
c2f26f36 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Move most of waitRead#/Write# from cmm to C

Moves it into the IOManager.c where we can follow the new pattern of
switching on the selected I/O manager.

- - - - -
457705a8 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Move most of the delay# impl from cmm to C

Moves it into the IOManager.c where we can follow the new pattern of
switching on the selected I/O manager.

Uses a new IOManager API: syncDelay, following the naming convention of
sync* for thread-synchronous I/O & timer/delay operations.

As part of porting from cmm to C, we maintain the rule that the
why_blocked gets accessed using load acquire and store release atomic
memory operations. There was one exception to this rule: in the delay#
primop cmm code on posix (not win32), the why_blocked was being updated
using a store relaxed, not a store release. I've no idea why. In this
convesion I'm playing it safe here and using store release consistently.

- - - - -
e93058e0 by Duncan Coutts at 2024-04-03T01:27:18-04:00
insertIntoSleepingQueue is no longer public

No longer defined in IOManager.h, just a private function in
IOManager.c. Since it is no longer called from cmm code, just from
syncDelay. It ought to get moved further into the select() I/O manager
impl, rather than living in IOManager.c.

On the other hand appendToIOBlockedQueue is still called from cmm code
in the win32-legacy I/O manager primops async{Read,Write}#, and it is
also used by the select() I/O manager. Update the CPP and comments to
reflect this.

- - - - -
60ce9910 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Move anyPendingTimeoutsOrIO impl from .h to .c

The implementation is eventually going to need to use more private
things, which will drag in unwanted includes into IOManager.h, so it's
better to move the impl out of the header file and into the .c file, at
the slight cost of it no longer being inline.

At the same time, change to the "switch (iomgr_type)" style.

- - - - -
f70b8108 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Take a simpler approach to gcc warnings in IOManager.c

We have lots of functions with conditional implementations for
different I/O managers. Some functions, for some I/O managers,
naturally have implementations that do nothing or barf. When only one
such I/O manager is enabled then the whole function implementation will
have an implementation that does nothing or barfs. This then results in
warnings from gcc that parameters are unused, or that the function
should be marked with attribute noreturn (since barf does not return).
The USED_IF_THREADS trick for fine-grained warning supression is fine
for just two cases, but an equivalent here would need
USED_IF_THE_ONLY_ENABLED_IOMGR_IS_X_OR_Y which would have combinitorial
blowup. So we take a coarse grained approach and simply disable these
two warnings for the whole file.

So we use a GCC pragma, with its handy push/pop support:

 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wsuggest-attribute=noreturn"
 #pragma GCC diagnostic ignored "-Wunused-parameter"

...

 #pragma GCC diagnostic pop

- - - - -
b48805b9 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Add a new trace class for the iomanager

It makes sense now for it to be separate from the scheduler class of
tracers.

Enabled with +RTS -Do. Document the -Do debug flag in the user guide.

- - - - -
f0c1f862 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Have the throwTo impl go via (new) IOManager APIs

rather than directly operating on the IO manager's data structures.

Specifically, when thowing an async exception to a thread that is
blocked waiting for I/O or waiting for a timer, then we want to cancel
that I/O waiting or cancel the timer. Currently this is done directly in
removeFromQueues() in RaiseAsync.c. We want it to go via proper APIs
both for modularity but also to let us support multiple I/O managers.

So add sync{IO,Delay}Cancel, which is the cancellation for the
corresponding sync{IO,Delay}. The implementations of these use the usual
"switch (iomgr_type)" style.

- - - - -
4f9e9c4e by Duncan Coutts at 2024-04-03T01:27:18-04:00
Move awaitEvent into a proper IOManager API

and have the scheduler use it.

Previously the scheduler calls awaitEvent directly, and awaitEvent is
implemented directly in the RTS I/O managers (select, win32). This
relies on the old scheme where there's a single active I/O manager for
each platform and RTS way.

We want to move that to go via an API in IOManager.{h,c} which can then
call out to the active I/O manager.

Also take the opportunity to split awaitEvent into two. The existing
awaitEvent has a bool wait parameter, to say if the call should be
blocking or non-blocking. We split this into two separate functions:
pollCompletedTimeoutsOrIO and awaitCompletedTimeoutsOrIO. We split them
for a few reasons: they have different post-conditions (specifically the
await version is supposed to guarantee that there are threads runnable
when it completes). Secondly, it is also anticipated that in future I/O
managers the implementations of the two cases will be simpler if they
are separated.

- - - - -
5ad4b30f by Duncan Coutts at 2024-04-03T01:27:18-04:00
Rename awaitEvent in select and win32 I/O managers

These are now just called from IOManager.c and are the per-I/O manager
backend impls (whereas previously awaitEvent was the entry point).

Follow the new naming convention in the IOManager.{h,c} of
awaitCompletedTimeoutsOrIO, with the I/O manager's name as a suffix:
so awaitCompletedTimeoutsOrIO{Select,Win32}.

- - - - -
d30c6bc6 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Tidy up a couple things in Select.{h,c}

Use the standard #include {Begin,End}Private.h style rather than
RTS_PRIVATE on individual decls.

And conditionally build the code for the select I/O manager based on
the new CPP IOMGR_ENABLED_SELECT rather than on THREADED_RTS.

- - - - -
4161f516 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Add an IOManager API for scavenging TSO blocked_info

When the GC scavenges a TSO it needs to scavenge the tso->blocked_info
but the blocked_info is a big union and what lives there depends on the
two->why_blocked, which for I/O-related reasons is something that in
principle is the responsibility of the I/O manager and not the GC. So
the right thing to do is for the GC to ask the I/O manager to sscavenge
the blocked_info if it encounters any I/O-related why_blocked reasons.

So we add scavengeTSOIOManager in IOManager.{h,c} with the usual style.

Now as it happens, right now, there is no special scavenging to do, so
the implementation of scavengeTSOIOManager is a fancy no-op. That's
because the select I/O manager uses only the fd and target members,
which are not GC pointers, and the win32-legacy I/O manager _ought_ to
be using GC-managed heap objects for the StgAsyncIOResult but it is
actually usingthe C heap, so again no GC pointers. If the win32-legacy
were doing this more sensibly, then scavengeTSOIOManager would be the
right place to do the GC magic.

Future I/O managers will need GC heap objects in the tso->blocked_info
and will make use of this functionality.

- - - - -
94a87d21 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Add I/O manager API notifyIOManagerCapabilitiesChanged

Used in setNumCapabilities.

It only does anything for MIO on Posix.

Previously it always invoked Haskell code, but that code only did
anything on non-Windows (and non-JS), and only threaded. That currently
effectively means the MIO I/O manager on Posix.

So now it only invokes it for the MIO Posix case.

- - - - -
3be6d591 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Select an I/O manager early in RTS startup

We need to select the I/O manager to use during startup before the
per-cap I/O manager initialisation.

- - - - -
aaa294d0 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Make struct CapIOManager be fully opaque

Provide an opaque (forward) definition in Capability.h (since the cap
contains a *CapIOManager) and then only provide a full definition in
a new file IOManagerInternals.h. This new file is only supposed to be
included by the IOManager implementation, not by its users. So that
means IOManager.c and individual I/O manager implementations.

The posix/Signals.c still needs direct access, but that should be
eliminated. Anything that needs direct access either needs to be clearly
part of an I/O manager (e.g. the sleect() one) or go via a proper API.

- - - - -
877a2a80 by Duncan Coutts at 2024-04-03T01:27:18-04:00
The select() I/O manager does have some global initialisation

It's just to make sure an exception CAF is a GC root.

- - - - -
9c51473b by Duncan Coutts at 2024-04-03T01:27:18-04:00
Add tracing for the main I/O manager actions

Using the new tracer class.

Note: The unconditional definition of showIOManager should be
compatible with the debugTrace change in 7c7d1f6.

Co-authored-by: Pi Delport <pi at well-typed.com>

- - - - -
c7d3e3a3 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Include the default I/O manager in the +RTS --info output

Document the extra +RTS --info output in the user guide

- - - - -
8023bad4 by Duncan Coutts at 2024-04-03T01:27:18-04:00
waitRead# / waitWrite# do not work for win32-legacy I/O manager

Previously it was unclear that they did not work because the code path
was shared with other I/O managers (in particular select()).

Following the code carefully shows that what actually happens is that
the calling thread would block forever: the thread will be put into the
blocked queue, but no other action is scheduled that will ever result in
it getting unblocked.

It's better to just fail loudly in case anyone accidentally calls it,
also it's less confusing code.

- - - - -
83a74d20 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Conditionally ignore some GCC warnings

Some GCC versions don't know about some warnings, and they complain
that we're ignoring unknown warnings. So we try to ignore the warning
based on the GCC version.

- - - - -
1adc6fa4 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Accept changes to base-exports

All the changes are in fact not changes at all.

Previously, the IoSubSystem data type was defined in GHC.RTS.Flags and
exported from both GHC.RTS.Flags and GHC.IO.SubSystem. Now, the data
type is defined in GHC.IO.SubSystem and still exported from both
modules.

Therefore, the same exports and same instances are still available from
both modules. But the base-exports records only the defining module, and
so it looks like a change when it is fully compatible.

Related: we do add a deprecation to the export of the type via
GHC.RTS.Flags, telling people to use the export from GHC.IO.SubSystem.

Also the sort order for some unrelated Show instances changed. No idea
why.

The same changes apply in the other versions, with a few more changes
due to sort order weirdness.

- - - - -
8d950968 by Duncan Coutts at 2024-04-03T01:27:18-04:00
Accept metric decrease in T12227

I can't think of any good reason that anything in this MR should have
changed the number of allocations, up or down.

(Yes this is an empty commit.)

Metric Decrease:
    T12227

- - - - -
e869605e by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Several improvements to the handling of coercions

* Make `mkSymCo` and `mkInstCo` smarter
  Fixes #23642

* Fix return role of `SelCo` in the coercion optimiser.
  Fixes #23617

* Make the coercion optimiser `opt_trans_rule` work better for newtypes
  Fixes #23619

- - - - -
1efd0714 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
FloatOut: improve floating for join point

See the new Note [Floating join point bindings].

* Completely get rid of the complicated join_ceiling nonsense, which
  I have never understood.

* Do not float join points at all, except perhaps to top level.

* Some refactoring around wantToFloat, to treat Rec and NonRec more
  uniformly

- - - - -
9c00154d by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Improve eta-expansion through call stacks

See Note [Eta expanding through CallStacks] in GHC.Core.Opt.Arity

This is a one-line change, that fixes an inconsistency
-               || isCallStackPredTy ty
+               || isCallStackPredTy ty || isCallStackTy ty

- - - - -
95a9a172 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Spelling, layout, pretty-printing only

- - - - -
bdf1660f by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Improve exprIsConApp_maybe a little

Eliminate a redundant case at birth.  This sometimes reduces
Simplifier iterations.

See Note [Case elim in exprIsConApp_maybe].

- - - - -
609cd32c by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Inline GHC.HsToCore.Pmc.Solver.Types.trvVarInfo

When exploring compile-time regressions after meddling with the Simplifier, I
discovered that GHC.HsToCore.Pmc.Solver.Types.trvVarInfo was very delicately
balanced.  It's a small, heavily used, overloaded function and it's important
that it inlines. By a fluke it was before, but at various times in my journey it
stopped doing so.  So I just added an INLINE pragma to it; no sense in depending
on a delicately-balanced fluke.

- - - - -
ae24c9bc by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Slight improvement in WorkWrap

Ensure that WorkWrap preserves lambda binders, in case of join points.  Sadly I
have forgotten why I made this change (it was while I was doing a lot of
meddling in the Simplifier, but
  * it does no harm,
  * it is slightly more efficient, and
  * presumably it made something better!

Anyway I have kept it in a separate commit.

- - - - -
e9297181 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Use named record fields for the CastIt { ... } data constructor

This is a pure refactor

- - - - -
b4581e23 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Remove a long-commented-out line

Pure refactoring

- - - - -
e026bdf2 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Simplifier improvements

This MR started as: allow the simplifer to do more in one pass,
arising from places I could see the simplifier taking two iterations
where one would do.  But it turned into a larger project, because
these changes unexpectedly made inlining blow up, especially join
points in deeply-nested cases.

The main changes are below.  There are also many new or rewritten Notes.

Avoiding simplifying repeatedly
~~~~~~~~~~~~~~~
See Note [Avoiding simplifying repeatedly]

* The SimplEnv now has a seInlineDepth field, which says how deep
  in unfoldings we are.  See Note [Inline depth] in Simplify.Env.
  Currently used only for the next point: avoiding repeatedly
  simplifying coercions.

* Avoid repeatedly simplifying coercions.
  see Note [Avoid re-simplifying coercions] in Simplify.Iteration
  As you'll see from the Note, this makes use of the seInlineDepth.

* Allow Simplify.Iteration.simplAuxBind to inline used-once things.
  This is another part of Note [Post-inline for single-use things], and
  is really good for reducing simplifier iterations in situations like
      case K e of { K x -> blah }
  wher x is used once in blah.

* Make GHC.Core.SimpleOpt.exprIsConApp_maybe do some simple case
  elimination.  Note [Case elim in exprIsConApp_maybe]

* Improve the case-merge transformation:
  - Move the main code to `GHC.Core.Utils.mergeCaseAlts`, to join `filterAlts`
    and friends.  See Note [Merge Nested Cases] in GHC.Core.Utils.
  - Add a new case for `tagToEnum#`; see wrinkle (MC3).
  - Add a new case to look through join points: see wrinkle (MC4)

postInlineUnconditionally
~~~~~~~~~~~~~~~~~~~~~~~~~
* Allow Simplify.Utils.postInlineUnconditionally to inline variables
  that are used exactly once. See Note [Post-inline for single-use things].

* Do not postInlineUnconditionally join point, ever.
  Doing so does not reduce allocation, which is the main point,
  and with join points that are used a lot it can bloat code.
  See point (1) of Note [Duplicating join points] in
  GHC.Core.Opt.Simplify.Iteration.

* Do not postInlineUnconditionally a strict (demanded) binding.
  It will not allocate a thunk (it'll turn into a case instead)
  so again the main point of inlining it doesn't hold.  Better
  to check per-call-site.

* Improve occurrence analyis for bottoming function calls, to help
  postInlineUnconditionally.  See Note [Bottoming function calls]
  in GHC.Core.Opt.OccurAnal

Inlining generally
~~~~~~~~~~~~~~~~~~
* In GHC.Core.Opt.Simplify.Utils.interestingCallContext,
  use RhsCtxt NonRecursive (not BoringCtxt) for a plain-seq case.
  See Note [Seq is boring]  Also, wrinkle (SB1), inline in that
  `seq` context only for INLINE functions (UnfWhen guidance).

* In GHC.Core.Opt.Simplify.Utils.interestingArg,
  - return ValueArg for OtherCon [c1,c2, ...], but
  - return NonTrivArg for OtherCon []
  This makes a function a little less likely to inline if all we
  know is that the argument is evaluated, but nothing else.

* isConLikeUnfolding is no longer true for OtherCon {}.
  This propagates to exprIsConLike.  Con-like-ness has /positive/
  information.

Join points
~~~~~~~~~~~
* Be very careful about inlining join points.
  See these two long Notes
    Note [Duplicating join points] in GHC.Core.Opt.Simplify.Iteration
    Note [Inlining join points] in GHC.Core.Opt.Simplify.Inline

* When making join points, don't do so if the join point is so small
  it will immediately be inlined; check uncondInlineJoin.

* In GHC.Core.Opt.Simplify.Inline.tryUnfolding, improve the inlining
  heuristics for join points. In general we /do not/ want to inline
  join points /even if they are small/.  See Note [Duplicating join points]
  GHC.Core.Opt.Simplify.Iteration.

  But sometimes we do: see Note [Inlining join points] in
  GHC.Core.Opt.Simplify.Inline; and the new `isBetterUnfoldingThan` function.

* Do not add an unfolding to a join point at birth.  This is a tricky one
  and has a long Note [Do not add unfoldings to join points at birth]
  It shows up in two places
  - In `mkDupableAlt` do not add an inlining
  - (trickier) In `simplLetUnfolding` don't add an unfolding for a
    fresh join point
  I am not fully satisifed with this, but it works and is well documented.

* In GHC.Core.Unfold.sizeExpr, make jumps small, so that we don't penalise
  having a non-inlined join point.

Performance changes
~~~~~~~~~~~~~~~~~~~
* Binary sizes fall by around 2.6%, according to nofib.

* Compile times improve slightly. Here are the figures over 1%.

  I investiate the biggest differnce in T18304. It's a very small module, just
  a few hundred nodes. The large percentage difffence is due to a single
  function that didn't quite inline before, and does now, making code size a
  bit bigger.  I decided gains outweighed the losses.

    Metrics: compile_time/bytes allocated (changes over +/- 1%)
    ------------------------------------------------
           CoOpt_Singletons(normal)   -9.2% GOOD
                LargeRecord(normal)  -23.5% GOOD
MultiComponentModulesRecomp(normal)   +1.2%
MultiLayerModulesTH_OneShot(normal)   +4.1%  BAD
                  PmSeriesS(normal)   -3.8%
                  PmSeriesV(normal)   -1.5%
                     T11195(normal)   -1.3%
                     T12227(normal)  -20.4% GOOD
                     T12545(normal)   -3.2%
                     T12707(normal)   -2.1% GOOD
                     T13253(normal)   -1.2%
                 T13253-spj(normal)   +8.1%  BAD
                     T13386(normal)   -3.1% GOOD
                     T14766(normal)   -2.6% GOOD
                     T15164(normal)   -1.4%
                     T15304(normal)   +1.2%
                     T15630(normal)   -8.2%
                    T15630a(normal)          NEW
                     T15703(normal)  -14.7% GOOD
                     T16577(normal)   -2.3% GOOD
                     T17516(normal)  -39.7% GOOD
                     T18140(normal)   +1.2%
                     T18223(normal)  -17.1% GOOD
                     T18282(normal)   -5.0% GOOD
                     T18304(normal)  +10.8%  BAD
                     T18923(normal)   -2.9% GOOD
                      T1969(normal)   +1.0%
                     T19695(normal)   -1.5%
                     T20049(normal)  -12.7% GOOD
                    T21839c(normal)   -4.1% GOOD
                      T3064(normal)   -1.5%
                      T3294(normal)   +1.2%  BAD
                      T4801(normal)   +1.2%
                      T5030(normal)  -15.2% GOOD
                   T5321Fun(normal)   -2.2% GOOD
                      T6048(optasm)  -16.8% GOOD
                       T783(normal)   -1.2%
                      T8095(normal)   -6.0% GOOD
                      T9630(normal)   -4.7% GOOD
                      T9961(normal)   +1.9%  BAD
                      WWRec(normal)   -1.4%
        info_table_map_perf(normal)   -1.3%
                 parsing001(normal)   +1.5%

                          geo. mean   -2.0%
                          minimum    -39.7%
                          maximum    +10.8%

* Runtimes generally improve. In the testsuite perf/should_run gives:
   Metrics: runtime/bytes allocated
   ------------------------------------------
             Conversions(normal)   -0.3%
                 T13536a(optasm)  -41.7% GOOD
                   T4830(normal)   -0.1%
           haddock.Cabal(normal)   -0.1%
            haddock.base(normal)   -0.1%
        haddock.compiler(normal)   -0.1%

                       geo. mean   -0.8%
                       minimum    -41.7%
                       maximum     +0.0%

* For runtime, nofib is a better test.  The news is mostly good.
  Here are the number more than +/- 0.1%:

    # bytes allocated
    ==========================++==========
       imaginary/digits-of-e1 ||  -14.40%
       imaginary/digits-of-e2 ||   -4.41%
          imaginary/paraffins ||   -0.17%
               imaginary/rfib ||   -0.15%
       imaginary/wheel-sieve2 ||   -0.10%
                real/compress ||   -0.47%
                   real/fluid ||   -0.10%
                  real/fulsom ||   +0.14%
                  real/gamteb ||   -1.47%
                      real/gg ||   -0.20%
                   real/infer ||   +0.24%
                     real/pic ||   -0.23%
                  real/prolog ||   -0.36%
                     real/scs ||   -0.46%
                 real/smallpt ||   +4.03%
        shootout/k-nucleotide ||  -20.23%
              shootout/n-body ||   -0.42%
       shootout/spectral-norm ||   -0.13%
              spectral/boyer2 ||   -3.80%
         spectral/constraints ||   -0.27%
          spectral/hartel/ida ||   -0.82%
                spectral/mate ||  -20.34%
                spectral/para ||   +0.46%
             spectral/rewrite ||   +1.30%
              spectral/sphere ||   -0.14%
    ==========================++==========
                    geom mean ||   -0.59%

    real/smallpt has a huge nest of local definitions, and I
    could not pin down a reason for a regression.  But there are
    three big wins!

Metric Decrease:
    CoOpt_Singletons
    LargeRecord
    T12227
    T12707
    T13386
    T13536a
    T14766
    T15703
    T16577
    T17516
    T18223
    T18282
    T18923
    T21839c
    T20049
    T5321Fun
    T5030
    T6048
    T8095
    T9630
    T783
Metric Increase:
    MultiLayerModulesTH_OneShot
    T13253-spj
    T18304
    T18698a
    T9961
    T3294

- - - - -
27db3c5e by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Testsuite message changes from simplifier improvements

- - - - -
271a7812 by Simon Peyton Jones at 2024-04-03T01:27:55-04:00
Account for bottoming functions in OccurAnal

This fixes #24582, a small but long-standing bug

- - - - -
0fde229f by Ben Gamari at 2024-04-04T07:04:58-04:00
testsuite: Introduce template-haskell-exports test

- - - - -
0c4a9686 by Luite Stegeman at 2024-04-04T07:05:39-04:00
Update correct counter in bumpTickyAllocd

- - - - -
5f085d3a by Fendor at 2024-04-04T14:47:33-04:00
Replace `SizedSeq` with `FlatBag` for flattened structure

LinkedLists are notoriously memory ineffiecient when all we do is
traversing a structure.
As 'UnlinkedBCO' has been identified as a data structure that impacts
the overall memory usage of GHCi sessions, we avoid linked lists and
prefer flattened structure for storing.

We introduce a new memory efficient representation of sequential
elements that has special support for the cases:

* Empty
* Singleton
* Tuple Elements

This improves sharing in the 'Empty' case and avoids the overhead of
'Array' until its constant overhead is justified.

- - - - -
82cfe10c by Fendor at 2024-04-04T14:47:33-04:00
Compact FlatBag array representation

`Array` contains three additional `Word`'s we do not need in `FlatBag`. Move
`FlatBag` to `SmallArray`.

Expand the API of SmallArray by `sizeofSmallArray` and add common
traversal functions, such as `mapSmallArray` and `foldMapSmallArray`.
Additionally, allow users to force the elements of a `SmallArray`
via `rnfSmallArray`.

- - - - -
36a75b80 by Andrei Borzenkov at 2024-04-04T14:48:10-04:00
Change how invisible patterns represented in  haskell syntax and TH AST (#24557)

Before this patch:
  data ArgPat p
    = InvisPat (LHsType p)
    | VisPat (LPat p)

With this patch:
  data Pat p
    = ...
    | InvisPat (LHsType p)
    ...

And the same transformation in the TH land. The rest of the
changes is just updating code to handle new AST and writing tests
to check if it is possible to create invalid states using TH.

Metric Increase:
    MultiLayerModulesTH_OneShot

- - - - -
28009fbc by Matthew Pickering at 2024-04-04T14:48:46-04:00
Fix off by one error in seekBinNoExpand and seekBin

- - - - -
9b9e031b by Ben Gamari at 2024-04-04T21:30:08-04:00
compiler: Allow more types in GHCForeignImportPrim

For many, many years `GHCForeignImportPrim` has suffered from the rather
restrictive limitation of not allowing any non-trivial types in arguments
or results. This limitation was justified by the code generator allegely
barfing in the presence of such types.

However, this restriction appears to originate well before the NCG
rewrite and the new NCG does not appear to have any trouble with such
types (see the added `T24598` test). Lift this restriction.

Fixes #24598.

- - - - -
1324b862 by Alan Zimmerman at 2024-04-04T21:30:44-04:00
EPA: Use EpaLocation not SrcSpan in ForeignDecls

This allows us to update them for makeDeltaAst in ghc-exactprint

- - - - -
19883a23 by Alan Zimmerman at 2024-04-05T16:58:17-04:00
EPA: Use EpaLocation for RecFieldsDotDot

So we can update it to a delta position in makeDeltaAst if needed.

- - - - -
e8724327 by Matthew Pickering at 2024-04-05T16:58:53-04:00
Remove accidentally committed test.hs

- - - - -
88cb3e10 by Fendor at 2024-04-08T09:03:34-04:00
Avoid UArray when indexing is not required

`UnlinkedBCO`'s can occur many times in the heap. Each `UnlinkedBCO`
references two `UArray`'s but never indexes them. They are only needed
to encode the elements into a `ByteArray#`. The three words for
the lower bound, upper bound and number of elements are essentially
unused, thus we replace `UArray` with a wrapper around `ByteArray#`.
This saves us up to three words for each `UnlinkedBCO`.

Further, to avoid re-allocating these words for `ResolvedBCO`, we repeat
the procedure for `ResolvedBCO` and add custom `Binary` and `Show` instances.

For example, agda's repl session has around 360_000 UnlinkedBCO's,
so avoiding these three words is already saving us around 8MB residency.

- - - - -
f2cc1107 by Fendor at 2024-04-08T09:04:11-04:00
Never UNPACK `FastMutInt` for counting z-encoded `FastString`s

In `FastStringTable`, we count the number of z-encoded FastStrings
that exist in a GHC session.
We used to UNPACK the counters to not waste memory, but live retainer
analysis showed that we allocate a lot of `FastMutInt`s, retained by
`mkFastZString`.

We lazily compute the `FastZString`, only incrementing the counter when the `FastZString` is
forced.
The function `mkFastStringWith` calls `mkZFastString` and boxes the
`FastMutInt`, leading to the following core:

    mkFastStringWith
      = \ mk_fs _  ->
             = case stringTable of
                { FastStringTable _ n_zencs segments# _ ->
                    ...
                         case ((mk_fs (I# ...) (FastMutInt n_zencs))
                            `cast` <Co:2> :: ...)
                            ...

Marking this field as `NOUNPACK` avoids this reboxing, eliminating the
allocation of a fresh `FastMutInt` on every `FastString` allocation.

- - - - -
c6def949 by Matthew Pickering at 2024-04-08T16:06:51-04:00
Force in_multi to avoid retaining entire hsc_env

- - - - -
fbb91a63 by Fendor at 2024-04-08T16:06:51-04:00
Eliminate name thunk in declaration fingerprinting

Thunk analysis showed that we have about 100_000 thunks (in agda and
`-fwrite-simplified-core`) pointing to the name of the name decl.
Forcing this thunk fixes this issue.

The thunk created here is retained by the thunk created by forkM, it is
better to eagerly force this because the result (a `Name`) is already
retained indirectly via the `IfaceDecl`.

- - - - -
3b7b0c1c by Alan Zimmerman at 2024-04-08T16:07:27-04:00
EPA: Use EpaLocation in WarningTxt

This allows us to use an EpDelta if needed when using makeDeltaAst.

- - - - -
12b997df by Alan Zimmerman at 2024-04-08T16:07:27-04:00
EPA: Move DeltaPos and EpaLocation' into GHC.Types.SrcLoc

This allows us to use a NoCommentsLocation for the possibly trailing
comma location in a StringLiteral.
This in turn allows us to correctly roundtrip via makeDeltaAst.

- - - - -
868c8a78 by Fendor at 2024-04-09T08:51:50-04:00
Prefer packed representation for CompiledByteCode

As there are many 'CompiledByteCode' objects alive during a GHCi
session, representing its element in a more packed manner improves space
behaviour at a minimal cost.

When running GHCi on the agda codebase, we find around 380 live
'CompiledByteCode' objects. Packing their respective 'UnlinkedByteCode'
can save quite some pointers.

- - - - -
be3bddde by Alan Zimmerman at 2024-04-09T08:52:26-04:00
EPA: Capture all comments in a ClassDecl

Hopefully the final fix needed for #24533

- - - - -
3d0806fc by Jade at 2024-04-10T05:39:53-04:00
Validate -main-is flag using parseIdentifier

Fixes #24368

- - - - -
dd530bb7 by Rodrigo Mesquita at 2024-04-10T05:40:29-04:00
rts: free error message before returning

Fixes a memory leak in rts/linker/PEi386.c

- - - - -
e008a19a by Alexis King at 2024-04-10T05:40:29-04:00
linker: Avoid linear search when looking up Haskell symbols via dlsym

See the primary Note [Looking up symbols in the relevant objects] for a
more in-depth explanation.

When dynamically loading a Haskell symbol (typical when running a splice or
GHCi expression), before this commit we would search for the symbol in
all dynamic libraries that were loaded. However, this could be very
inefficient when too many packages are loaded (which can happen if there are
many package dependencies) because the time to lookup the would be
linear in the number of packages loaded.

This commit drastically improves symbol loading performance by
introducing a mapping from units to the handles of corresponding loaded
dlls. These handles are returned by dlopen when we load a dll, and can
then be used to look up in a specific dynamic library.

Looking up a given Name is now much more precise because we can get
lookup its unit in the mapping and lookup the symbol solely in the
handles of the dynamic libraries loaded for that unit.

In one measurement, the wait time before the expression was executed
went from +-38 seconds down to +-2s.

This commit also includes Note [Symbols may not be found in pkgs_loaded],
explaining the fallback to the old behaviour in case no dll can be found
in the unit mapping for a given Name.

Fixes #23415

Co-authored-by: Rodrigo Mesquita (@alt-romes)

- - - - -
dcfaa190 by Rodrigo Mesquita at 2024-04-10T05:40:29-04:00
rts: Make addDLL a wrapper around loadNativeObj

Rewrite the implementation of `addDLL` as a wrapper around the more
principled `loadNativeObj` rts linker function. The latter should be
preferred while the former is preserved for backwards compatibility.

`loadNativeObj` was previously only available on ELF platforms, so this
commit further refactors the rts linker to transform loadNativeObj_ELF
into loadNativeObj_POSIX, which is available in ELF and MachO platforms.

The refactor made it possible to remove the `dl_mutex` mutex in favour
of always using `linker_mutex` (rather than a combination of both).

Lastly, we implement `loadNativeObj` for Windows too.

- - - - -
12931698 by Rodrigo Mesquita at 2024-04-10T05:40:29-04:00
Use symbol cache in internal interpreter too

This commit makes the symbol cache that was used by the external
interpreter available for the internal interpreter too.

This follows from the analysis in #23415 that suggests the internal
interpreter could benefit from this cache too, and that there is no good
reason not to have the cache for it too. It also makes it a bit more
uniform to have the symbol cache range over both the internal and
external interpreter.

This commit also refactors the cache into a function which is used by
both `lookupSymbol` and also by `lookupSymbolInDLL`, extending the
caching logic to `lookupSymbolInDLL` too.

- - - - -
dccd3ea1 by Ben Gamari at 2024-04-10T05:40:29-04:00
testsuite: Add test for lookupSymbolInNativeObj

- - - - -
1b1a92bd by Alan Zimmerman at 2024-04-10T05:41:05-04:00
EPA: Remove unnecessary XRec in CompleteMatchSig

The XRec for [LIdP pass] is not needed for exact printing, remove it.

- - - - -
6e18ce2b by Ben Gamari at 2024-04-12T08:16:09-04:00
users-guide: Clarify language extension documentation

Over the years the users guide's language extension documentation has
gone through quite a few refactorings. In the process some of the
descriptions have been rendered non-sensical. For instance, the
description of `NoImplicitPrelude` actually describes the semantics of
`ImplicitPrelude`.

To fix this we:

 * ensure that all extensions are named in their "positive" sense (e.g.
   `ImplicitPrelude` rather than `NoImplicitPrelude`).
 * rework the documentation to avoid flag-oriented wording
   like "enable" and "disable"
 * ensure that the polarity of the documentation is consistent with
   reality.

Fixes #23895.

- - - - -
a933aff3 by Zubin Duggal at 2024-04-12T08:16:45-04:00
driver: Make `checkHomeUnitsClosed` faster

The implementation of `checkHomeUnitsClosed` was traversing every single path
in the unit dependency graph - this grows exponentially and quickly grows to be
infeasible on larger unit dependency graphs.

Instead we replace this with a faster implementation which follows from the
specificiation of the closure property - there is a closure error if there are
units which are both are both (transitively) depended upon by home units and
(transitively) depend on home units, but are not themselves home units.

To compute the set of units required for closure, we first compute the closure
of the unit dependency graph, then the transpose of this closure, and find all
units that are reachable from the home units in the transpose of the closure.

- - - - -
23c3e624 by Andreas Klebinger at 2024-04-12T08:17:21-04:00
RTS: Emit warning when -M < -H

Fixes #24487

- - - - -
d23afb8c by Ben Gamari at 2024-04-12T08:17:56-04:00
testsuite: Add broken test for CApiFFI with -fprefer-bytecode

See #24634.

- - - - -
a4bb3a51 by Ben Gamari at 2024-04-12T08:18:32-04:00
base: Deprecate GHC.Pack

As proposed in #21461.

Closes #21540.

- - - - -
55eb8c98 by Ben Gamari at 2024-04-12T08:19:08-04:00
ghc-internal: Fix mentions of ghc-internal in deprecation warnings

Closes #24609.

- - - - -
b0fbd181 by Ben Gamari at 2024-04-12T08:19:44-04:00
rts: Implement set_initial_registers for AArch64

Fixes #23680.

- - - - -
14c9ec62 by Ben Gamari at 2024-04-12T08:20:20-04:00
ghcup-metadata: Use Debian 9 binaries on Ubuntu 16, 17

Closes #24646.

- - - - -
35a1621e by Ben Gamari at 2024-04-12T08:20:55-04:00
Bump unix submodule to 2.8.5.1

Closes #24640.

- - - - -
a1c24df0 by Finley McIlwaine at 2024-04-12T08:21:31-04:00
Correct default -funfolding-use-threshold in docs

- - - - -
0255d03c by Oleg Grenrus at 2024-04-12T08:22:07-04:00
FastString is a __Modified__ UTF-8

- - - - -
c3489547 by Matthew Pickering at 2024-04-12T13:13:44-04:00
rts: Improve tracing message when nursery is resized

It is sometimes more useful to know how much bigger or smaller the
nursery got when it is resized.

In particular I am trying to investigate situations where we end up with
fragmentation due to the nursery (#24577)

- - - - -
5e4f4ba8 by Simon Peyton Jones at 2024-04-12T13:14:20-04:00
Don't generate wrappers for `type data` constructors with StrictData

Previously, the logic for checking if a data constructor needs a wrapper or not
would take into account whether the constructor's fields have explicit
strictness (e.g., `data T = MkT !Int`), but the logic would _not_ take into
account whether `StrictData` was enabled. This meant that something like `type
data T = MkT Int` would incorrectly generate a wrapper for `MkT` if
`StrictData` was enabled, leading to the horrible errors seen in #24620. To fix
this, we disable generating wrappers for `type data` constructors altogether.

Fixes #24620.

Co-authored-by: Ryan Scott <ryan.gl.scott at gmail.com>

- - - - -
3ecb7512 by Ben Gamari at 2024-04-15T11:33:48-04:00
rel-eng: Fix mktemp usage in recompress-all

We need a temporary directory, not a file.

- - - - -


29 changed files:

- .gitlab/generate-ci/gen_ci.hs
- .gitlab/jobs.yaml
- .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py
- .gitlab/rel_eng/recompress-all
- .gitlab/rel_eng/upload.sh
- compiler/GHC.hs
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Names/TH.hs
- compiler/GHC/Builtin/PrimOps.hs-boot
- compiler/GHC/Builtin/Types/Prim.hs
- compiler/GHC/ByteCode/Asm.hs
- compiler/GHC/ByteCode/Linker.hs
- compiler/GHC/ByteCode/Types.hs
- compiler/GHC/Cmm/Dominators.hs
- compiler/GHC/Cmm/ThreadSanitizer.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/LateCC/OverloadedCalls.hs
- compiler/GHC/Core/Map/Type.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/FloatOut.hs
- compiler/GHC/Core/Opt/Monad.hs
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Core/Opt/Pipeline.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify.hs
- compiler/GHC/Core/Opt/Simplify/Env.hs
- compiler/GHC/Core/Opt/Simplify/Inline.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/470331cd89b6184125f8876085c2aae073d3ea43...3ecb75124d5bcccedb5698240bda264ae49ecde2

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