-
62ae97de
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Handle heap allocation failure in I/O primops
The current I/O managers do not use allocateMightFail, but future ones
will. To support this properly we need to be able to return to the
primop with a failure. We simply use a bool return value.
Currently however, we will just throw an exception rather than calling
the GC because that's what all the other primops do too.
For the general issue of primops invoking GC and retrying, see
https://gitlab.haskell.org/ghc/ghc/-/issues/24105
-
cb9093f5
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Move (and rename) scheduleStartSignalHandlers into RtsSignals.h
Previously it was a local helper (static) function in Schedule.c.
Rename it to startPendingSignalHandlers and deifine it as an inline
header function in RtsSignals.h. So it should still be fast.
Each (new style) I/O manager is going to need to do the same, so eliminating
the duplication now makes sense.
-
9736d44a
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Reduce detail in printThreadBlockage I/O blocking cases
The printThreadBlockage is used in debug tracing output.
For the cases BlockedOn{Read,Write,Delay} the output previously included
the fd that was being waited on, and the delay target wake time.
Superficially this sounds useful, but it's clearly not that useful
because it was already wrong for the Win32 non-threaded I/O manager. In
that situation it will print garbage (the async_result pointer, cast to
a fd or a time).
So given that it apparently never mattered that the information was
accurate, then it's hardly a big jump to say it doesn't matter if it is
present at all.
A good reason to remove it is that otherwise we have to make a new
API and a per-I/O manager implementation to fetch the information. And
for some I/O manager implementations, this information is not available.
It is not available in the win32 non-threaded I/O manager. And for some
future Linux ones, there is no need for the fd to be stored, so storing
it would be just extra space used for very little gain.
So the simplest thing is to just remove the detail.
-
bc0f2d5d
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Add TimeoutQueue.{c,h} and corresponding tests
A data structure used to efficiently manage a collection of timeouts.
It is a priority queue based on absolute expiry time. It uses 64bit
high-precision Time for the keys. The values are normal closures which
allows for example using MVars for unblocking.
It is common in many applications for timeouts to be created and then
deleted or altered before they expire. Thus the choice of data structure
for timeouts should support this efficiently. The implementation choice
here is a leftist heap with the extra feature that it supports deleting
arbitrary elements, provided the caller retain a pointer to the element.
While the deleteMin operation takes O(log n) time, as in all heap
structures, the delete operation for arbitrary elements /typically/
takes O(1), and only O(log n) in the worst case. In practice, when
managing thousands of timeouts it can be a factor of 10 faster to delete
a random timeout queue element than to remove the minimum element. This
supports the common use case.
The plan is to use it in some of the RTS-side I/O managers to support
their timer functionality. In this use case the heap value will be an
MVar used for each timeout to unblock waiting threads.
-
d1679c9d
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Add ClosureTable.{c,h} and corresponding tests
A table of pointers to closures on the GC heap with stable indexes.
It provides O(1) alloc, free and lookup. The table can be expanded
using a simple doubling strategy: in which case allocation is typically
O(1) and occasionally O(n) for overall amortised O(1). No shrinking is
used.
The table itself is heap allocated, and points to other heap objects.
As such it's necessary to use markClosureTable to ensure the table is
used as a GC root to keep the table entries alive, and maintain proper
pointers to them as the GC moves heap objects about.
It is designed to be allocated and accesses exclusively from a single
capability, enabling it to work without any locking. It is thus similar
to the StablePtr table, but per-capability which removes the need for
locking. It _should_ also provide lower GC pause times with the
non-moving GC by spending only O(1) time in markClosureTable, vs O(n)
for markStablePtrTable.
The plan is to use it in some of the I/O managers to keep track of
in-flight I/O operations (but not timers). This allows the tracking
info to be kept on the (unpinned) GC heap, and shared with Haskell
code, and by putting a pointer to the tracking information in a table,
the index remains stable and can be passed via foreign code (like the
kernel).
-
78cb8dd5
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Add the StgAsyncIOOp closure type
This is intended to be used by multiple I/O managers to help with
tracking in-flight I/O operations.
It is called asynchronous because from the point of view of the RTS we
have many such operations in progress at once. From the point of view of
a Haskell thread of course it can look synchronous.
-
a2839896
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Add StgAsyncIOOp and StgTimeoutQueue to tso->block_info
These will be used by new I/O managers, for threads blocked on I/O or
timeouts.
-
fdc2451c
by Duncan Coutts at 2025-09-12T13:23:33-04:00
Add a new I/O manager based on poll()
This is a proof of concept I/O manager, to show how to add new ones
neatly, using the ClosureTable and TimeoutQueue infrastructure.
It uses the old unix poll() API, so it is of course limited in
performance by that, but it should have the benefit of wide
compatibility. Also we neatly avoid a name clash with the existing
select() I/O manager.
Compared to the select() I/O manager:
1. beause it uses poll() it is not limited to 1024 file descriptors
(but it's still O(n) so don't expect great performance);
2. it should have much faster threadDelay (when using it in lots of
threads at once) because it's based on the new TimeoutQueue which is
O(log n) rather than O(n).
Some of the code related to timers/timouts is put into a shared module
rts/posix/Timeout.{h,c} since it is intended to be shared with other
similar I/O managers.
-
6c273b76
by Duncan Coutts at 2025-09-12T13:23:34-04:00
Document the I/O managers in the user guide
and note the new poll I/O manager in the release notes.
-
824fab74
by Duncan Coutts at 2025-09-12T13:23:34-04:00
Use the poll() I/O manager by default
That is, for the non-threaded RTS, prefer the poll I/O manager over the
legacy select() one, if both can be enabled.
This patch is primarily for CI testing, so we should probably remove
this patch before merging. We can change defaults later after wider
testing and feedback.
-
39392532
by Luite Stegeman at 2025-09-12T13:24:16-04:00
Support larger unboxed sums
Change known constructor encoding for sums in interfaces to use
11 bits for both the arity and the alternative (up from 8 and 6,
respectively)
-
2af12e21
by Luite Stegeman at 2025-09-12T13:24:16-04:00
Decompose padding smallest-first in Cmm toplevel data constructors
This makes each individual padding value aligned
-
418fa78f
by Luite Stegeman at 2025-09-12T13:24:16-04:00
Use slots smaller than word as tag for smaller unboxed sums
This packs unboxed sums more efficiently by allowing
Word8, Word16 and Word32 for the tag field if the number of
constructors is small enough
-
8d7e912f
by Rodrigo Mesquita at 2025-09-12T17:57:24-04:00
ghc-toolchain: Use ByteOrder rather than new Endianness
Don't introduce a duplicate datatype when the previous one is equivalent
and already used elsewhere. This avoids unnecessary translation between
the two.
-
7d378476
by Rodrigo Mesquita at 2025-09-12T17:57:24-04:00
Read Toolchain.Target files rather than 'settings'
This commit makes GHC read `lib/targets/default.target`, a file with a
serialized value of `ghc-toolchain`'s `GHC.Toolchain.Target`.
Moreover, it removes all the now-redundant entries from `lib/settings`
that are configured as part of a `Target` but were being written into
`settings`.
This makes it easier to support multiple targets from the same compiler
(aka runtime retargetability). `ghc-toolchain` can be re-run many times
standalone to produce a `Target` description for different targets, and,
in the future, GHC will be able to pick at runtime amongst different
`Target` files.
This commit only makes it read the default `Target` configured in-tree
or configured when installing the bindist.
The remaining bits of `settings` need to be moved to `Target` in follow
up commits, but ultimately they all should be moved since they are
per-target relevant.
Fixes #24212
On Windows, the constant overhead of parsing a slightly more complex
data structure causes some small-allocation tests to wiggle around 1 to
2 extra MB (1-2% in these cases).
-------------------------
Metric Increase:
MultiLayerModulesTH_OneShot
T10421
T10547
T12234
T12425
T13035
T18140
T18923
T9198
TcPlugin_RewritePerf
-------------------------
-
e0780a16
by Rodrigo Mesquita at 2025-09-12T17:57:24-04:00
ghc-toolchain: Move TgtHasLibm to per-Target file
TargetHasLibm is now part of the per-target configuration
Towards #26227
-
8235dd8c
by Rodrigo Mesquita at 2025-09-12T17:57:24-04:00
ghc-toolchain: Move UseLibdw to per-Target file
To support DWARF unwinding, the RTS must be built with the -f+libdw flag
and with the -DUSE_LIBDW macro definition. These flags are passed on
build by Hadrian when --enable-dwarf-unwinding is specified at configure
time.
Whether the RTS was built with support for DWARF is a per-target
property, and as such, it was moved to the per-target
GHC.Toolchain.Target.Target file.
Additionally, we keep in the target file the include and library paths
for finding libdw, since libdw should be checked at configure time (be
it by configure, or ghc-toolchain, that libdw is properly available).
Preserving the user-given include paths for libdw facilitates in the
future building the RTS on demand for a given target (if we didn't keep
that user input, we couldn't)
Towards #26227
-
d5ecf2e8
by Rodrigo Mesquita at 2025-09-12T17:57:25-04:00
ghc-toolchain: Make "Support SMP" a query on a Toolchain.Target
"Support SMP" is merely a function of target, so we can represent it as
such in `ghc-toolchain`.
Hadrian queries the Target using this predicate to determine how to
build GHC, and GHC queries the Target similarly to report under --info
whether it "Support SMP"
Towards #26227
-
e07b031a
by Rodrigo Mesquita at 2025-09-12T17:57:25-04:00
ghc-toolchain: Make "tgt rts linker only supports shared libs" function on Target
Just like with "Support SMP", "target RTS linker only supports shared
libraries" is a predicate on a `Target` so we can just compute it when
necessary from the given `Target`.
Towards #26227
-
14123ee6
by Simon Peyton Jones at 2025-09-12T17:58:07-04:00
Solve forall-constraints via an implication, again
In this earlier commit:
commit 953fd8f1dc080f1c56e3a60b4b7157456949be29
Author: Simon Peyton Jones <simon.peytonjones@gmail.com>
Date: Mon Jul 21 10:06:43 2025 +0100
Solve forall-constraints immediately, or not at all
I used a all-or-nothing strategy for quantified constraints
(aka forall-constraints). But alas that fell foul of #26315,
and #26376.
So this MR goes back to solving a quantified constraint by
turning it into an implication; UNLESS we are simplifying
constraints from a SPECIALISE pragma, in which case the
all-or-nothing strategy is great. See:
Note [Solving a Wanted forall-constraint]
Other stuff in this MR:
* TcSMode becomes a record of flags, rather than an enumeration
type; much nicer.
* Some fancy footwork to avoid error messages worsening again
(The above MR made them better; we want to retain that.)
See `GHC.Tc.Errors.Ppr.pprQCOriginExtra`.
-------------------------
Metric Decrease:
T24471
-------------------------
-
e6c192e2
by Simon Peyton Jones at 2025-09-12T17:58:07-04:00
Add a test case for #26396
...same bug ast #26315
-
8f3d80ff
by Luite Stegeman at 2025-09-13T08:43:09+02:00
Use mkVirtHeapOffsets for reconstructing terms in RTTI
This makes mkVirtHeapOffsets the single source of truth for
finding field offsets in closures.
-
eb389338
by Luite Stegeman at 2025-09-13T08:43:09+02:00
Sort non-pointer fields by size for more efficient packing
This sorts non-pointer fields in mkVirtHeapOffsets, always
storing the largest field first. The relative order of
equally sized fields remains unchanged.
This reduces wasted padding/alignment space in closures with
differently sized fields.
-
99b233f4
by Alison at 2025-09-13T16:51:04-04:00
ghc-heap: Fix race condition with profiling builds
Apply the same fix from Closures.hs (64fd0fac83) to Heap.hs by adding
empty imports to make way-dependent dependencies visible to `ghc -M`.
Fixes #15197, #26407
-
77deaa7a
by Cheng Shao at 2025-09-14T21:29:45-04:00
hadrian: build in-tree gmp with -fvisibility=hidden
When hadrian builds in-tree gmp, it should build the shared objects
with -fvisibility=hidden. The gmp symbols are only used by bignum
logic in ghc-internal and shouldn't be exported by the ghc-internal
shared library. We should always strive to keep shared library symbol
table lean, which benefits platforms with slow dynamic linker or even
hard limits about how many symbols can be exported (e.g. macos dyld,
win32 dll and wasm dyld).
-
42a18960
by Cheng Shao at 2025-09-14T21:30:26-04:00
Revert "wasm: add brotli compression for ghci browser mode"
This reverts commit 731217ce68a1093b5f9e26a07d5bd2cdade2b352.
Benchmarks show non-negligible overhead when browser runs on the same
host, which is the majority of actual use cases.
-
e6755b9f
by Cheng Shao at 2025-09-14T21:30:26-04:00
wasm: remove etag logic in ghci browser mode web server
This commit removes the etag logic in dyld script's ghci browser mode
web server. It was meant to support caching logic of wasm shared
libraries, but even if the port is manually specified to make caching
even relevant, for localhost the extra overhead around etag logic is
simply not worth it according to benchmarks.
-
ac5859b9
by sheaf at 2025-09-16T14:58:38-04:00
Add 'Outputable Natural' instance
This commit adds an Outputable instance for the Natural natural-number type,
as well as a "natural :: Natural -> SDoc" function that mirrors the existing
"integer" function.
-
d48ebc23
by Cheng Shao at 2025-09-16T14:59:18-04:00
autoconf: emit warning instead of error for FIND_PYTHON logic
This patch makes FIND_PYTHON logic emit warning instead of error, so
when the user doesn't expect to run the testsuite driver (especially
when installing a bindist), python would not be mandatory. Fixes #26347.
-
54b5950e
by Sylvain Henry at 2025-09-17T04:45:18-04:00
Print fully qualified unit names in name mismatch
It's more user-friendly to directly print the right thing instead of
requiring the user to retry with the additional `-dppr-debug` flag.
-
403cb665
by Ben Gamari at 2025-09-17T04:46:00-04:00
configure: Fix consistency between distrib and source CC check
Previously distrib/configure.ac did not
include `cc`.
Closes #26394.
-
2dcd4cb9
by Oleg Grenrus at 2025-09-17T04:46:41-04:00
Use isPrint in showUnique
The comment say
```
-- Avoid emitting non-printable characters in pretty uniques. See #25989.
```
so let the code do exactly that.
There are tags (at least : and 0 .. 9) which weren't in A .. z range.
-
e5dd754b
by Oleg Grenrus at 2025-09-17T04:46:42-04:00
Shorten in-module links in hyperlinked source
Instead of href="This.Module#ident" to just "#ident"
-
63189b2c
by Oleg Grenrus at 2025-09-17T04:46:42-04:00
Use showUnique in internalAnchorIdent
Showing the key of Unique as a number is generally not a great idea.
GHC Unique has a tag in high bits, so the raw number is unnecessarily
big.
So now we have
```html
<a href="#l-rvgK"><span class="hs-identifier hs-var hs-var">bar</span></a>
```
instead of
```html
<a href="#local-6989586621679015689"><span class="hs-identifier hs-var hs-var">bar</span></a>
```
Together with previous changes of shorter intra-module links the effect
on compressed files is not huge, that is expected as we simply remove
repetitive contents which pack well.
```
12_694_206 Agda-2.9.0-docs-orig.tar.gz
12_566_065 Agda-2.9.0-docs.tar.gz
```
However when unpacked, the difference can be significant,
e.g. Agda's largest module source got 5% reduction:
```
14_230_117 Agda.Syntax.Parser.Parser.html
13_422_109 Agda.Syntax.Parser.Parser.html
```
The whole hyperlinked source code directory got similar reduction
```
121M Agda-2.9.0-docs-orig/src
114M Agda-2.9.0-docs/src
```
For the reference, sources are about 2/3 of the generated haddocks
```
178M Agda-2.9.0-docs-old
172M Agda-2.9.0-docs
```
so we get around 3.5% size reduction overall. Not bad for a small local
changes.
-
6f63f57b
by Stefan Schulze Frielinghaus at 2025-09-17T04:47:22-04:00
rts: Fix alignment for gen_workspace #26334
After a0fa4941903272c48b050d24e93eec819eff51bd bootstrap is broken on
s390x and errors out with
rts/sm/GCThread.h:207:5: error:
error: alignment of array elements is greater than element size
207 | gen_workspace gens[];
| ^~~~~~~~~~~~~
The alignment constraint is applied via the attribute to the type
gen_workspace and leaves the underlying type struct gen_workspace_
untouched. On Aarch64, x86, and s390x the struct has a size of 128
bytes. On Aarch64 and x86 the alignments of 128 and 64 are divisors of
the size, respectively, which is why the type is a viable member type
for an array. However, on s390x, the alignment is 256 and therefore is
not a divisor of the size and hence cannot be used for arrays.
Basically I see two fixes here. Either decrease the alignment
requirement on s390x, or by applying the alignment constraint on the
struct itself. The former might affect performance as noted in
a0fa4941903272c48b050d24e93eec819eff51bd. The latter introduces padding
bits whenever necessary in order to ensure that
sizeof(gen_workspace[N])==N*sizeof(gen_workspace) holds which is done by
this patch.
-
06d25623
by Cheng Shao at 2025-09-17T19:32:27-04:00
ghci: add :shell command
This patch adds a new :shell command to ghci which works similarly to
:!, except it guarantees to run the command via sh -c. On POSIX hosts
the behavior is identical to :!, but on Windows it uses the msys2
shell instead of system cmd.exe shell. This is convenient when writing
simple ghci scripts that run simple POSIX commands, and the behavior
can be expected to be coherent on both Windows and POSIX.
Co-authored-by: Codex <codex@openai.com>
-
186054f7
by Cheng Shao at 2025-09-17T19:32:27-04:00
testsuite: remove legacy :shell trick
This commit makes use of the built-in :shell functionality in ghci in
the test cases, and remove the legacy :shell trick.
-
0a3a4aa3
by Cheng Shao at 2025-09-17T19:32:27-04:00
docs: document :shell in ghci
This commit documents the :shell command in ghci.
Co-authored-by: Codex <codex@openai.com>
-
a4ff12bb
by Cheng Shao at 2025-09-17T19:33:09-04:00
ghc-internal: fix codepages program
codepages was not properly updated during the base -> ghc-internal
migration, this commit fixes it.
-
7e094def
by Cheng Shao at 2025-09-17T19:33:09-04:00
ghc-internal: relax ucd2haskell cabal upper bounds
This commit relaxes ucd2haskell cabal upper bounds to make it runnable
via ghc 9.12/9.14.
-
7077c9f7
by Cheng Shao at 2025-09-17T19:33:09-04:00
ghc-internal: update to unicode 17.0.0
This commit updates the generated code in ghc-internal to match
unicode 17.0.0.
-
cef8938f
by sheaf at 2025-09-17T19:34:09-04:00
Bad record update msg: allow out-of-scope datacons
This commit ensures that, when we encounter an invalid record update
(because no constructor exists which contains all of the record fields
mentioned in the record update), we graciously handle the situation in
which the constructors themselves are not in scope. In that case,
instead of looking up the constructors in the GlobalRdrEnv, directly
look up their GREInfo using the lookupGREInfo function.
Fixes #26391
-
a2d9d7c2
by sheaf at 2025-09-17T19:34:09-04:00
Improve Notes about disambiguating record updates
This commit updates the notes [Disambiguating record updates] and
[Type-directed record disambiguation], in particular adding more
information about the deprecation status of type-directed disambiguation
of record updates.
-
2f3c3905
by Cheng Shao at 2025-09-18T17:11:31+02:00
rel-eng: update fedora image to 42
This patch is a part of #25876 and updates fedora image to 42.