-
4038a28b
by Andreas Klebinger at 2025-10-30T12:38:52-04:00
Add a perf test for #26425
-
f997618e
by Andreas Klebinger at 2025-10-30T12:38:52-04:00
OccAnal: Be stricter for better compiler perf.
In particular we are now stricter:
* When combining usageDetails.
* When computing binder info.
In combineUsageDetails when combining the underlying adds we compute a
new `LocalOcc` for each entry by combining the two existing ones.
Rather than wait for those entries to be forced down the road we now
force them immediately. Speeding up T26425 by about 10% with little
effect on the common case.
We also force binders we put into the Core AST everywhere now.
Failure to do so risks leaking the occ env used to set the binders
OccInfo.
For T26425 compiler residency went down by a factor of ~10x.
Compile time also improved by a factor of ~1.6.
-------------------------
Metric Decrease:
T18698a
T26425
T9233
-------------------------
-
5618645b
by Vladislav Zavialov at 2025-10-30T12:39:33-04:00
Fix namespace specifiers in subordinate exports (#12488)
This patch fixes an oversight in the `lookupChildrenExport` function that
caused explicit namespace specifiers of subordinate export items to be
ignored:
module M (T (type A)) where -- should be rejected
data T = A
Based on the `IEWrappedName` data type, there are 5 cases to consider:
1. Unadorned name: P(X)
2. Named default: P(default X)
3. Pattern synonym: P(pattern X)
4. Type name: P(type X)
5. Data name: P(data X)
Case 1 is already handled correctly; cases 2 and 3 are parse errors; and
it is cases 4 and 5 that we are concerned with in this patch.
Following the precedent established in `LookupExactName`, we introduce
a boolean flag in `LookupChildren` to control whether to look up in all
namespaces or in a specific one. If an export item is accompanied by an
explicit namespace specifier `type` or `data`, we restrict the lookup in
`lookupGRE` to a specific namespace.
The newly introduced diagnostic `TcRnExportedSubordinateNotFound`
provides error messages and suggestions more tailored to this context
than the previously used `reportUnboundName`.
-
f75ab223
by Peter Trommler at 2025-10-31T18:43:13-04:00
ghc-toolchain: detect PowerPC 64 bit ABI
Check preprocessor macro defined for ABI v2 and assume v1 otherwise.
Fixes #26521
-
d086c474
by Peter Trommler at 2025-10-31T18:43:13-04:00
ghc-toolchain: refactor, move lastLine to Utils
-
995dfe0d
by Vladislav Zavialov at 2025-10-31T18:43:54-04:00
Tests for -Wduplicate-exports, -Wdodgy-exports
Add test cases for the previously untested diagnostics:
[GHC-51876] TcRnDupeModuleExport
[GHC-64649] TcRnNullExportedModule
This also revealed a typo (incorrect capitalization of "module") in the
warning text for TcRnDupeModuleExport, which is now fixed.
-
f6961b02
by Cheng Shao at 2025-11-01T00:08:01+01:00
wasm: reformat dyld source code
This commit reformats dyld source code with prettier, to avoid
introducing unnecessary diffs in subsequent patches when they're
formatted before committing.
-
0c9032a0
by Cheng Shao at 2025-11-01T00:08:01+01:00
wasm: simplify _initialize logic in dyld
This commit simplifies how we _initialize a wasm shared library in
dyld and removes special treatment for libc.so, see added comment for
detailed explanation.
-
ec1b40bd
by Cheng Shao at 2025-11-01T00:08:01+01:00
wasm: support running dyld fully client side in the browser
This commit refactors the wasm dyld script so that it can be used to
load and run wasm shared libraries fully client-side in the browser
without needing a wasm32-wasi-ghci backend:
- A new `DyLDBrowserHost` class is exported, which runs in the browser
and uses the in-memory vfs without any RPC calls. This meant to be
used to create a `rpc` object for the fully client side use cases.
- The exported `main` function now can be used to load user-specified
shared libraries, and the user can use the returned `DyLD` instance
to run their own exported Haskell functions.
- The in-browser wasi implementation is switched to
https://github.com/haskell-wasm/browser_wasi_shim for bugfixes and
major performance improvements not landed upstream yet.
- When being run by deno, it now correctly switches to non-nodejs code
paths, so it's more convenient to test dyld logic with deno.
See added comments for details, as well as the added `playground001`
test case for an example of using it to build an in-browser Haskell
playground.
-
8f3e481f
by Cheng Shao at 2025-11-01T00:08:01+01:00
testsuite: add playground001 to test haskell playground
This commit adds the playground001 test case to test the haskell
playground in browser, see comments for details.
-
af40606a
by Cheng Shao at 2025-11-01T00:08:04+01:00
Revert "testsuite: add T26431 test case"
This reverts commit 695036686f8c6d78611edf3ed627608d94def6b7. T26431
is now retired, wasm ghc internal-interpreter logic is tested by
playground001.
-
86c82745
by Vladislav Zavialov at 2025-11-01T07:24:29-04:00
Supplant TcRnExportHiddenComponents with TcRnDodgyExports (#26534)
Remove a bogus special case in lookup_ie_kids_all,
making TcRnExportHiddenComponents obsolete.
-
fcf6331e
by Richard Eisenberg at 2025-11-03T08:33:05+00:00
Refactor fundep solving
This commit is a large-scale refactor of the increasingly-messy code that
handles functional dependencies. It has virtually no effect on what compiles
but improves error messages a bit. And it does the groundwork for #23162.
The big picture is described in
Note [Overview of functional dependencies in type inference]
in GHC.Tc.Solver.FunDeps
* New module GHC.Tc.Solver.FunDeps contains all the fundep-handling
code for the constraint solver.
* Fundep-equalities are solved in a nested scope; they may generate
unifications but otherwise have no other effect.
See GHC.Tc.Solver.FunDeps.solveFunDeps
The nested needs to start from the Givens in the inert set, but
not the Wanteds; hence a new function `resetInertCans`, used in
`nestFunDepsTcS`.
* That in turn means that fundep equalities never show up in error
messages, so the complicated FunDepOrigin tracking can all disappear.
* We need to be careful about tracking unifications, so we kick out
constraints from the inert set after doing unifications. Unification
tracking has been majorly reformed: see Note [WhatUnifications] in
GHC.Tc.Utils.Unify.
A good consequence is that the hard-to-grok `resetUnificationFlag`
has been replaced with a simpler use of
`reportCoarseGrainUnifications`
Smaller things:
* Rename `FunDepEqn` to `FunDepEqns` since it contains multiple
type equalities.
Some compile time improvement
Metrics: compile_time/bytes allocated
Baseline
Test value New value Change
---------------------- --------------------------------------
T5030(normal) 173,839,232 148,115,248 -14.8% GOOD
hard_hole_fits(normal) 286,768,048 284,015,416 -1.0%
geo. mean -0.2%
minimum -14.8%
maximum +0.3%
Metric Decrease:
T5030
-
231adc30
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
QuickLook's tcInstFun should make instantiation variables directly
tcInstFun must make "instantiation variables", not regular
unification variables, when instantiating function types. That was
previously implemented by a hack: set the /ambient/ level to QLInstTyVar.
But the hack finally bit me, when I was refactoring WhatUnifications.
And it was always wrong: see the now-expunged (TCAPP2) note.
This commit does it right, by making tcInstFun call its own
instantiation functions. That entails a small bit of duplication,
but the result is much, much cleaner.
-
39d4a24b
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Build implication for constraints from (static e)
This commit addresses #26466, by buiding an implication for the
constraints arising from a (static e) form. The implication has
a special ic_info field of StaticFormSkol, which tells the constraint
solver to use an empty set of Givens.
See (SF3) in Note [Grand plan for static forms]
in GHC.Iface.Tidy.StaticPtrTable
This commit also reinstates an `assert` in GHC.Tc.Solver.Equality.
The test `StaticPtrTypeFamily` was failing with an assertion failure,
but it now works.
-
2e2aec1e
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Comments about defaulting representation equalities
-
52a4d1da
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Improve tracking of rewriter-sets
This refactor substantially improves the treatment of so-called
"rewriter-sets" in the constraint solver.
The story is described in the rewritten
Note [Wanteds rewrite Wanteds: rewriter-sets]
in GHC.Tc.Types.Constraint
Some highlights
* Trace the free coercion holes of a filled CoercionHole,
in CoercionPlusHoles. See Note [Coercion holes] (COH5)
This avoids taking having to take the free coercion variables
of a coercion when zonking a rewrriter-set
* Many knock on changes
* Make fillCoercionHole take CoercionPlusHoles as its argument
rather than to separate arguments.
* Similarly setEqIfWanted, setWantedE, wrapUnifierAndEmit.
* Be more careful about passing the correct CoHoleSet to
`rewriteEqEvidence` and friends
* Make kickOurAfterFillingCoercionHole more clever. See
new Note [Kick out after filling a coercion hole]
Smaller matters
* Rename RewriterSet to CoHoleSet
* Add special-case helper `rewriteEqEvidenceSwapOnly`
-
3e78e1ba
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Tidy up constraint solving for foralls
* In `can_eq_nc_forall` make sure to track Givens that are used
in the nested solve step.
* Tiny missing-swap bug-fix in `lookup_eq_in_qcis`
* Fix some leftover mess from
commit 14123ee646f2b9738a917b7cec30f9d3941c13de
Author: Simon Peyton Jones <simon.peytonjones@gmail.com>
Date: Wed Aug 20 00:35:48 2025 +0100
Solve forall-constraints via an implication, again
Specifically, trySolveImplication is now dead.
-
973f2c25
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Do not treat CoercionHoles as free variables in coercions
This fixes a long-standing wart in the free-variable finder;
now CoercionHoles are no longer treated as a "free variable"
of a coercion.
I got big and unexpected performance regressions when making
this change. Turned out that CallArity didn't discover that
the free variable finder could be eta-expanded, which gave very
poor code.
So I re-used Note [The one-shot state monad trick] for Endo,
resulting in GHC.Utils.EndoOS. Very simple, big win.
-
c2b8a0f9
by Simon Peyton Jones at 2025-11-03T08:33:05+00:00
Update debug-tracing in CallArity
No effect on behaviour, and commented out anyway
-
9aa5ee99
by Simon Peyton Jones at 2025-11-03T08:33:28+00:00
Comments only -- remove dangling Note references
-
6683f183
by Simon Peyton Jones at 2025-11-03T08:33:28+00:00
Accept error message wibbles
-
3ba3d9f9
by Luite Stegeman at 2025-11-04T00:59:41-05:00
rts: fix eager black holes: record mutated closure and fix assertion
This fixes two problems with handling eager black holes, introduced
by a1de535f762bc23d4cf23a5b1853591dda12cdc9.
- the closure mutation must be recorded even for eager black holes,
since the mutator has mutated it before calling threadPaused
- The assertion that an unmarked eager black hole must be owned by
the TSO calling threadPaused is incorrect, since multiple threads
can race to claim the black hole.
fixes #26495
-
b5508f2c
by Rodrigo Mesquita at 2025-11-04T14:10:56+00:00
build: Relax ghc/ghc-boot Cabal bound to 3.16
Fixes #26202
-
c5b3541f
by Rodrigo Mesquita at 2025-11-04T14:10:56+00:00
cabal-reinstall: Use haddock-api +in-tree-ghc
Fixes #26202
-
c6d4b945
by Rodrigo Mesquita at 2025-11-04T14:10:56+00:00
cabal-reinstall: Pass --strict to Happy
This is necessary to make the generated Parser build successfully
This mimics Hadrian, which always passes --strict to happy.
Fixes #26202
-
79df1e0e
by Rodrigo Mesquita at 2025-11-04T14:10:56+00:00
genprimopcode: Require higher happy version
I've bumped the happy version to forbid deprecated Happy versions which
don't successfully compile.
-
fa5d33de
by Simon Peyton Jones at 2025-11-05T08:35:40-05:00
Add a HsWrapper optimiser
This MR addresses #26349, by introduceing optSubTypeHsWrapper.
There is a long
Note [Deep subsumption and WpSubType]
in GHC.Tc.Types.Evidence that explains what is going on.
-
ea58cae5
by Simon Peyton Jones at 2025-11-05T08:35:40-05:00
Improve mkWpFun_FRR
This commit ensures that `mkWpFun_FRR` directly produces a `FunCo` in
the cases where it can.
(Previously called `mkWpFun` which in turn optimised to a `FunCo`, but
that made the smarts in `mkWpFun` /essential/ rather than (as they
should be) optional.
-
5cdcfaed
by Ben Gamari at 2025-11-06T09:01:36-05:00
compiler: Exclude units with no exposed modules from unused package check
Such packages cannot be "used" in the Haskell sense of the word yet
are nevertheless necessary as they may provide, e.g., C object code or
link flags.
Fixes #24120.
-
74b8397a
by Brandon Chinn at 2025-11-06T09:02:19-05:00
Replace deprecated argparse.FileType
-
36ddf988
by Ben Gamari at 2025-11-06T09:03:01-05:00
Bump unix submodule to 2.8.8.0
Closes #26474.
-
c32b3a29
by fendor at 2025-11-06T09:03:43-05:00
Fix assertion in `postStringLen` to account for \0 byte
We fix the assertion to handle trailing \0 bytes in `postStringLen`.
Before this change, the assertion looked like this:
ASSERT(eb->begin + eb->size > eb->pos + len + 1);
Let's assume some values to see why this is actually off by one:
eb->begin = 0
eb->size = 1
eb->pos = 0
len = 1
then the assertion would trigger correctly:
0 + 1 > 0 + 1 + 1 => 1 > 2 => false
as there is not enough space for the \0 byte (which is the trailing +1).
However, if we change `eb->size = 2`, then we do have enough space for a
string of length 1, but the assertion still fails:
0 + 2 > 0 + 1 + 1 => 2 > 2 => false
Which causes the assertion to fail if there is exactly enough space for
the string with a trailing \0 byte.
Clearly, the assertion should be `>=`!
If we switch around the operand, it should become more obvious that `<=`
is the correct comparison:
ASSERT(eb->pos + len + 1 <= eb->begin + eb->size);
This is expresses more naturally that the current position plus the
length of the string (and the null byte) must be smaller or equal to the
overall size of the buffer.
This change also is in line with the implementation in
`hasRoomForEvent` and `hasRoomForVariableEvent`:
```
StgBool hasRoomForEvent(EventsBuf *eb, EventTypeNum eNum)
{
uint32_t size = ...;
if (eb->pos + size > eb->begin + eb->size)
...
```
the check `eb->pos + size > eb->begin + eb->size` is identical to
`eb->pos + size <= eb->begin + eb->size` plus a negation.
-
3034a6f2
by Ben Gamari at 2025-11-06T09:04:24-05:00
Bump os-string submodule to 2.0.8
-
39567e85
by Cheng Shao at 2025-11-06T09:05:06-05:00
rts: use computed goto for instruction dispatch in the bytecode interpreter
This patch uses computed goto for instruction dispatch in the bytecode
interpreter. Previously instruction dispatch is done by a classic
switch loop, so executing the next instruction requires two jumps: one
to the start of the switch loop and another to the case block based on
the instruction tag. By using computed goto, we can build a jump table
consisted of code addresses indexed by the instruction tags
themselves, so executing the next instruction requires only one jump,
to the destination directly fetched from the jump table.
Closes #12953.
-
93fc7265
by sheaf at 2025-11-06T21:33:24-05:00
Correct hasFixedRuntimeRep in matchExpectedFunTys
This commit fixes a bug in the representation-polymormorphism check in
GHC.Tc.Utils.Unify.matchExpectedFunTys. The problem was that we put
the coercion resulting from hasFixedRuntimeRep in the wrong place,
leading to the Core Lint error reported in #26528.
The change is that we have to be careful when using 'mkWpFun': it
expects **both** the expected and actual argument types to have a
syntactically fixed RuntimeRep, as explained in Note [WpFun-FRR-INVARIANT]
in GHC.Tc.Types.Evidence.
On the way, this patch improves some of the commentary relating to
other usages of 'mkWpFun' in the compiler, in particular in the view
pattern case of 'tc_pat'. No functional changes, but some stylistic
changes to make the code more readable, and make it easier to understand
how we are upholding the WpFun-FRR-INVARIANT.
Fixes #26528
-
c052c724
by Simon Peyton Jones at 2025-11-06T21:34:06-05:00
Fix a horrible shadowing bug in implicit parameters
Fixes #26451. The change is in GHC.Tc.Solver.Monad.updInertDicts
where we now do /not/ delete /Wanted/ implicit-parameeter constraints.
This bug has been in GHC since 9.8! But it's quite hard to provoke;
I contructed a tests in T26451, but it was hard to do so.
-
b253013e
by Georgios Karachalias at 2025-11-07T17:21:57-05:00
Remove the `CoreBindings` constructor from `LinkablePart`
Adjust HscRecompStatus to disallow unhydrated WholeCoreBindings
from being passed as input to getLinkDeps (which would previously
panic in this case).
Fixes #26497
-
ac7b737e
by Sylvain Henry at 2025-11-07T17:22:51-05:00
Testsuite: pass ext-interp test way (#26552)
Note that some tests are still marked as broken with the ext-interp way
(see #26552 and #14335)
-
3c2f4bb4
by sheaf at 2025-11-11T11:47:28-05:00
Preserve user-written kinds in data declarations
This commit ensures that we preserve the user-written kind for data
declarations, e.g. in
type T2T = Type -> Type
type D :: T2T
data D a where { .. }
that we preserve the user-written kind of D as 'T2T', instead of
expanding the type synonym 'T2T' during kind checking.
We do this by storing 'tyConKind' separately from 'tyConResKind'. This
means that 'tyConKind' is not necessarily equal to
'mkTyConKind binders res_kind', as e.g. in the above example the former
is 'T2T' while the latter is 'Type -> Type'.
This is explained in Note [Preserve user-written TyCon kind] in GHC.Core.TyCon.
This is particularly important for Haddock, as the kinds stored in
interface files affect the generated documentation, and we want to
preserve the user-written types as much as possible.
-
19859584
by sheaf at 2025-11-11T11:47:28-05:00
Store user-written datacon tvs in interface files
This commit ensures we store the user-written quantified type variables
of data constructors in interface files, e.g. in
data D a where
MkD1 :: forall x. x -> D x
MkD2 :: forall u v. u -> v -> D v
The previous behaviour was to rename the universal variables to match
the universal variables of the data constructor. This was undesirable
because the names that end up in interface files end up mattering for
generated Haddock documentation; it's better to preserve the user-written
type variables.
Moreover, the universal variables may not have been user-written at all,
e.g. in an example such as:
type T2T = Type -> Type
data G :: T2T where
MkG :: forall x. D x
Here GHC will invent the type variable name 'a' for the first binder of
the TyCon G. We really don't want to then rename the user-written 'x'
into the generated 'a'.
-
034b2056
by sheaf at 2025-11-11T11:47:28-05:00
DataCon univ_tvs names: pick TyCon over inferred
This commit changes how we compute the names of universal type variables
in GADT data constructors. This augments the existing logic that chose
which type variable name to use, in GHC.Tc.TyCl.mkGADTVars. We continue
to prefer DataCon tv names for user-written binders, but we now prefer
TyCon tv names for inferred (non-user-written) DataCon binders.
This makes a difference in examples such as:
type (:~~:) :: k1 -> k2 -> Type
data a :~~: b where
HRefl :: a :~~: a
Before this patch, we ended up giving HRefl the type:
forall {k2}. forall (a :: k2). a :~~: a
whereas we now give it the type:
forall {k1}. forall (a :: k1). a :~~: a
The important part isn't really 'k1' or 'k2', but more that the inferred
type variable names of the DataCon can be arbitrary/unpredictable (as
they are chosen by GHC and depend on how unification proceeds), so it's
much better to use the more predictable TyCon type variable names.
-
95078d00
by sheaf at 2025-11-11T11:47:28-05:00
Backpack Rename: use explicit record construction
This commit updates the Backpack boilerplate in GHC.Iface.Rename to
use explicit record construction rather than record update. This makes
sure that the code stays up to date when the underlying constructors
change (e.g. new fields are added). The rationale is further explained
in Note [Prefer explicit record construction].
-
2bf36263
by sheaf at 2025-11-11T11:47:28-05:00
Store # eta binders in TyCon and use for Haddock
This commit stores the number of TyCon binders that were introduced by
eta-expansion (by the function GHC.Tc.Gen.HsType.splitTyConKind).
This is then used to pretty-print the TyCon as the user wrote it, e.g.
for
type Effect :: (Type -> Type) -> Type -> Type
data State s :: Effect where {..} -- arity 3
GHC will eta-expand the data declaration to
data State s a b where {..}
but also store in the 'TyCon' that the number of binders introduced by
this eta expansion is 2. This allows us, in
'Haddock.Convert.synifyTyConKindSig', to recover the original user-written
syntax, preserving the user's intent in Haddock documentation.
See Note [Inline kind signatures with GADTSyntax] in Haddock.Convert.
-
6c91582f
by Matthew Pickering at 2025-11-11T11:48:12-05:00
driver: Properly handle errors during LinkNode steps
Previously we were not properly catching errors during the LinkNode step
(see T9930fail test).
This is fixed by wrapping the `LinkNode` action in `wrapAction`, the
same handler which is used for module compilation.
Fixes #26496
-
e1e1eb32
by Matthew Pickering at 2025-11-11T11:48:54-05:00
driver: Remove unecessary call to hscInsertHPT
This call was left-over from e9445c013fbccf9318739ca3d095a3e0a2e1be8a
If you follow the functions which call `upsweep_mod`, they immediately
add the interface to the HomePackageTable when `upsweep_mod` returns.
-
b22777d4
by ARATA Mizuki at 2025-11-11T11:49:44-05:00
LLVM backend: Pass the +evex512 attribute to LLVM 18+ if -mavx512f is set
The newer LLVM requires the +evex512 attribute to enable use of ZMM registers.
LLVM exhibits a backward-compatible behavior if the cpu is `x86-64`, but not if `penryn`.
Therefore, on macOS, where the cpu is set to `penryn`, we need to explicitly pass +evex512.
Fixes #26410
-
6ead7d06
by Vladislav Zavialov at 2025-11-11T11:50:26-05:00
Comments only in GHC.Parser.PostProcess.Haddock
Remove outdated Note [Register keyword location], as the issue it describes
was addressed by commit 05eb50dff2fcc78d025e77b9418ddb369db49b9f.
-
43fa8be8
by sheaf at 2025-11-11T11:51:18-05:00
localRegistersConflict: account for assignment LHS
This commit fixes a serious oversight in GHC.Cmm.Sink.conflicts,
specifically the code that computes which local registers conflict
between an assignment and a Cmm statement.
If we have:
assignment: <local_reg> = <expr>
node: <local_reg> = <other_expr>
then clearly the two conflict, because we cannot move one statement past
the other, as they assign two different values to the same local
register. (Recall that 'conflicts (local_reg,expr) node' is False if and
only if the assignment 'local_reg = expr' can be safely commuted past
the statement 'node'.)
The fix is to update 'GHC.Cmm.Sink.localRegistersConflict' to take into
account the following two situations:
(1) 'node' defines the LHS local register of the assignment,
(2) 'node' defines a local register used in the RHS of the assignment.
The bug is precisely that we were previously missing condition (1).
Fixes #26550
-
79dfcfe0
by sheaf at 2025-11-11T11:51:18-05:00
Update assigned register format when spilling
When we come to spilling a register to put new data into it, in
GHC.CmmToAsm.Reg.Linear.allocRegsAndSpill_spill, we need to:
1. Spill the data currently in the register. That is, do a spill
with a format that matches what's currently in the register.
2. Update the register assignment, allocating a virtual register to
this real register, but crucially **updating the format** of this
assignment.
Due to shadowing in the Haskell code for allocRegsAndSpill_spill, we
were mistakenly re-using the old format. This could lead to a situation
where:
a. We were using xmm6 to store a Double#.
b. We want to store a DoubleX2# into xmm6, so we spill the current
content of xmm6 to the stack using a scalar move (correct).
c. We update the register assignment, but we fail to update the format
of the assignment, so we continue to think that xmm6 stores a
Double# and not a DoubleX2#.
d. Later on, we need to spill xmm6 because it is getting clobbered by
another instruction. We then decide to only spill the lower 64 bits
of the register, because we still think that xmm6 only stores a
Double# and not a DoubleX2#.
Fixes #26542
-
aada5db9
by ARATA Mizuki at 2025-11-11T11:52:07-05:00
Fix the order of spill/reload instructions
The AArch64 NCG could emit multiple instructions for a single spill/reload,
but their order was not consistent between the definition and a use.
Fixes #26537
Co-authored-by: sheaf <sam.derbyshire@gmail.com>
-
64ec82ff
by Andreas Klebinger at 2025-11-11T11:52:48-05:00
Add hpc to release script
-
741da00c
by Ben Gamari at 2025-11-12T03:38:20-05:00
template-haskell: Better describe getQ semantics
Clarify that the state is a type-indexed map, as suggested by #26484.
-
8b080e04
by ARATA Mizuki at 2025-11-12T03:39:11-05:00
Fix incorrect markups in the User's Guide
* Correct markup for C--: "C-\-" in reST
* Fix internal links
* Fix code highlighting
* Fix inline code: Use ``code`` rather than `code`
* Remove extra backslashes
Fixes #16812
Co-authored-by: sheaf <sam.derbyshire@gmail.com>
-
a00840ea
by Simon Peyton Jones at 2025-11-14T15:23:56+00:00
Make TYPE and CONSTRAINT apart again
This patch finally fixes #24279.
* The story started with #11715
* Then #21623 articulated a plan, which made Type and Constraint
not-apart; a horrible hack but it worked. The main patch was
commit 778c6adca2c995cd8a1b84394d4d5ca26b915dac
Author: Simon Peyton Jones <simonpj@microsoft.com>
Date: Wed Nov 9 10:33:22 2022 +0000
Type vs Constraint: finally nailed
* #24279 reported a bug in the above big commit; this small patch fixes it
commit af6932d6c068361c6ae300d52e72fbe13f8e1f18
Author: Simon Peyton Jones <simon.peytonjones@gmail.com>
Date: Mon Jan 8 10:49:49 2024 +0000
Make TYPE and CONSTRAINT not-apart
Issue #24279 showed up a bug in the logic in GHC.Core.Unify.unify_ty
which is supposed to make TYPE and CONSTRAINT be not-apart.
* Then !10479 implemented "unary classes".
* That change in turn allows us to make Type and Constraint apart again,
cleaning up the compiler and allowing a little bit more expressiveness.
It fixes the original hope in #24279, namely that `Type` and `Constraint`
should be distinct throughout.
-
c0a1e574
by Georgios Karachalias at 2025-11-15T05:14:31-05:00
Report all missing modules with -M
We now report all missing modules at once in GHC.Driver.Makefile.processDeps,
as opposed to only reporting a single missing module. Fixes #26551.
-
c9fa3449
by Sylvain Henry at 2025-11-15T05:15:26-05:00
JS: fix array index for registers
We used to store R32 in h$regs[-1]. While it's correct in JavaScript,
fix this to store R32 in h$regs[0] instead.
-
9e469909
by Sylvain Henry at 2025-11-15T05:15:26-05:00
JS: support more than 128 registers (#26558)
The JS backend only supported 128 registers (JS variables/array slots
used to pass function arguments). It failed in T26537 when 129
registers were required.
This commit adds support for more than 128 registers: it is now limited to
maxBound :: Int (compiler's Int). If we ever go above this threshold the
compiler now panics with a more descriptive message.
A few built-in JS functions were assuming 128 registers and have been
rewritten to use loops. Note that loops are only used for "high"
registers that are stored in an array: the 31 "low" registers are still
handled with JS global variables and with explicit switch-cases to
maintain good performance in the most common cases (i.e. few registers
used). Adjusting the number of low registers is now easy: just one
constant to adjust (GHC.StgToJS.Regs.lowRegsCount).
No new test added: T26537 is used as a regression test instead.
-
0a64a78b
by Sven Tennie at 2025-11-15T20:31:10-05:00
AArch64: Simplify CmmAssign and CmmStore
The special handling for floats was fake: The general case is always
used. So, the additional code path isn't needed (and only adds
complexity for the reader.)
-
15b311be
by sheaf at 2025-11-15T20:32:02-05:00
SimpleOpt: refactor & push coercions into lambdas
This commit improves the simple optimiser (in GHC.Core.SimpleOpt)
in a couple of ways:
- The logic to push coercion lambdas is shored up.
The function 'pushCoercionIntoLambda' used to be called in 'finish_app',
but this meant we could not continue to optimise the program after
performing this transformation.
Now, we call 'pushCoercionIntoLambda' as part of 'simple_app'.
Doing so can be important when dealing with unlifted newtypes,
as explained in Note [Desugaring unlifted newtypes].
- The code is re-structured to avoid duplication and out-of-sync
code paths.
Now, 'simple_opt_expr' defers to 'simple_app' for the 'App', 'Var',
'Cast' and 'Lam' cases. This means all the logic for those is
centralised in a single place (e.g. the 'go_lam' helper function).
To do this, the general structure is brought a bit closer to the
full-blown simplifier, with a notion of 'continuation'
(see 'SimpleContItem').
This commit also modifies GHC.Core.Opt.Arity.pushCoercionIntoLambda to
apply a substitution (a slight generalisation of its existing implementation).
-
b33284c7
by sheaf at 2025-11-15T20:32:02-05:00
Improve typechecking of data constructors
This commit changes the way in which we perform typecheck data
constructors, in particular how we make multiplicities line up.
Now, impedance matching occurs as part of the existing subsumption
machinery. See the revamped Note [Typechecking data constructors] in
GHC.Tc.Gen.App, as well as Note [Polymorphisation of linear fields]
in GHC.Core.Multiplicity.
This allows us to get rid of a fair amount of hacky code that was
added with the introduction of LinearTypes; in particular the logic of
GHC.Tc.Gen.Head.tcInferDataCon.
-------------------------
Metric Decrease:
T10421
T14766
T15164
T15703
T19695
T5642
T9630
WWRec
-------------------------
-
b6faf5d0
by sheaf at 2025-11-15T20:32:02-05:00
Handle unsaturated rep-poly newtypes
This commit allows GHC to handle unsaturated occurrences of unlifted
newtype constructors. The plan is detailed in
Note [Eta-expanding rep-poly unlifted newtypes]
in GHC.Tc.Utils.Concrete: for unsaturated unlifted newtypes, we perform
the appropriate representation-polymorphism check in tcInstFun.
-
682bf979
by Mike Pilgrem at 2025-11-16T16:44:14+00:00
Fix #26293 Valid stack.yaml for hadrian
-
acc70c3a
by Simon Peyton Jones at 2025-11-18T16:21:20-05:00
Fix a bug in defaulting
Addresses #26582
Defaulting was doing some unification but then failing to
iterate. Silly.
I discovered that the main solver was unnecessarily iterating even
if there was a unification for an /outer/ unification variable, so
I fixed that too.
-
c12fa73e
by Simon Peyton Jones at 2025-11-19T02:55:01-05:00
Make PmLit be in Ord, and use it in Map
This MR addresses #26514, by changing from
data PmAltConSet = PACS !(UniqDSet ConLike) ![PmLit]
to
data PmAltConSet = PACS !(UniqDSet ConLike) !(Map PmLit PmLit)
This matters when doing pattern-match overlap checking, when there
is a very large set of patterns. For most programs it makes
no difference at all.
For the N=5000 case of the repro case in #26514, compiler
mutator time (with `-fno-code`) goes from 1.9s to 0.43s.
All for the price for an Ord instance for PmLit
-
41b84f40
by sheaf at 2025-11-19T02:55:52-05:00
Add passing tests for #26311 and #26072
This commit adds two tests cases that now pass since landing the changes
to typechecking of data constructors in b33284c7.
Fixes #26072 #26311
-
1faa758a
by sheaf at 2025-11-19T02:55:52-05:00
mkCast: weaken bad cast warning for multiplicity
This commit weakens the warning message emitted when constructing a bad
cast in mkCast to ignore multiplicity.
Justification: since b33284c7, GHC uses sub-multiplicity coercions to
typecheck data constructors. The coercion optimiser is free to discard
these coercions, both for performance reasons, and because GHC's Core
simplifier does not (yet) preserve linearity.
We thus weaken 'mkCast' to use 'eqTypeIgnoringMultiplicity' instead of
'eqType', to avoid getting many spurious warnings about mismatched
multiplicities.
-
55eab80d
by Sylvain Henry at 2025-11-20T17:33:13-05:00
Build external interpreter program on demand (#24731)
This patch teaches GHC how to build the external interpreter program
when it is missing. As long as we have the `ghci` library, doing this is
trivial so most of this patch is refactoring for doing it sanely.
-
08bbc028
by Rodrigo Mesquita at 2025-11-20T17:33:54-05:00
Add tests for #23973 and #26565
These were fixed by 4af4f0f070f83f948e49ad5d7835fd91b8d3f0e6 in !10417
-
6b42232c
by sheaf at 2025-11-20T17:34:35-05:00
Mark T26410_ffi as fragile on Windows
As seen in #26595, this test intermittently fails on Windows.
This commit marks it as fragile, until we get around to fixing it.
-
b7b7c049
by Andrew Lelechenko at 2025-11-21T21:04:01+00:00
Add nubOrd / nubOrdBy to Data.List and Data.List.NonEmpty
As per https://github.com/haskell/core-libraries-committee/issues/336
-
352d5462
by Marc Scholten at 2025-11-22T10:33:03-05:00
Fix haddock test runner to handle UTF-8 output
xhtml 3000.4.0.0 now produces UTF-8 output instead of escaping non-ASCII characters.
When using --test-accept it previously wrote files in the wrong encoding
because they have not been decoded properly when reading the files.
-
48a3ed57
by Simon Peyton Jones at 2025-11-25T15:33:54+00:00
Add a fast-path for args=[] to occAnalApp
In the common case of having not arguments, occAnalApp
was doing redundant work.
-
951e5ed9
by Simon Peyton Jones at 2025-11-25T15:33:54+00:00
Fix a performance hole in the occurrence analyser
As #26425 showed, the clever stuff in
Note [Occurrence analysis for join points]
does a lot of duplication of usage details. This patch
improved matters with a little fancy footwork. It is
described in the new (W4) of the same Note.
Compile-time allocations go down slightly. Here are the changes
of +/- 0.5% or more:
T13253(normal) 329,369,244 326,395,544 -0.9%
T13253-spj(normal) 66,410,496 66,095,864 -0.5%
T15630(normal) 129,797,200 128,663,136 -0.9%
T15630a(normal) 129,212,408 128,027,560 -0.9%
T16577(normal) 6,756,706,896 6,723,028,512 -0.5%
T18282(normal) 128,462,070 125,808,584 -2.1% GOOD
T18698a(normal) 208,418,305 202,037,336 -3.1% GOOD
T18730(optasm) 136,981,756 136,208,136 -0.6%
T18923(normal) 58,103,088 57,745,840 -0.6%
T19695(normal) 1,386,306,272 1,365,609,416 -1.5%
T26425(normal) 3,344,402,957 2,457,811,664 -26.5% GOOD
T6048(optasm) 79,763,816 79,212,760 -0.7%
T9020(optasm) 225,278,408 223,682,440 -0.7%
T9961(normal) 303,810,717 300,729,168 -1.0% GOOD
geo. mean -0.5%
minimum -26.5%
maximum +0.4%
Metric Decrease:
T18282
T18698a
T26425
T9961
-
f1959dfc
by Simon Peyton Jones at 2025-11-26T11:58:07+00:00
Remove a quadratic-cost assertion check in mkCoreApp
See the new Note [Assertion checking in mkCoreApp]
-
98fa0d36
by Simon Hengel at 2025-11-27T17:54:57-05:00
Fix typo in docs/users_guide/exts/type_families.rst
-
5b97e5ce
by Simon Hengel at 2025-11-27T17:55:37-05:00
Fix broken RankNTypes example in user's guide
-
fa2aaa00
by Simon Peyton Jones at 2025-11-27T17:56:18-05:00
Switch off specialisation in ExactPrint
In !15057 (where we re-introduced -fpolymoprhic-specialisation) we found
that ExactPrint's compile time blew up by a factor of 5. It turned out
to be caused by bazillions of specialisations of `markAnnotated`.
Since ExactPrint isn't perf-critical, it does not seem worth taking
the performance hit, so this patch switches off specialisation in
this one module.
-
1fd25987
by Simon Peyton Jones at 2025-11-27T17:56:18-05:00
Switch -fpolymorphic-specialisation on by default
This patch addresses #23559.
Now that !10479 has landed and #26329 is fixed, we can switch on
polymorphic specialisation by default, addressing a bunch of other
tickets listed in #23559.
Metric changes:
* CoOpt_Singleton: +4% compiler allocations: we just get more
specialisations
* info_table_map_perf: -20% decrease in compiler allocations.
This is caused by using -fno-specialise in ExactPrint.hs
Without that change we get a 4x blow-up in compile time;
see !15058 for details
Metric Decrease:
info_table_map_perf
Metric Increase:
CoOpt_Singletons
-
b7fe7445
by Matthew Pickering at 2025-11-27T17:56:59-05:00
rts: Fix a deadlock with eventlog flush interval and RTS shutdown
The ghc_ticker thread attempts to flush at the eventlog tick interval, this requires
waiting to take all capabilities.
At the same time, the main thread is shutting down, the schedule is
stopped and then we wait for the ticker thread to finish.
Therefore we are deadlocked.
The solution is to use `newBoundTask/exitMyTask`, so that flushing can
cooperate with the scheduler shutdown.
Fixes #26573
-
1d4a1229
by sheaf at 2025-11-27T17:58:02-05:00
SimpleOpt: don't subst in pushCoercionIntoLambda
It was noticed in #26589 that the change in 15b311be was incorrect:
the simple optimiser carries two different substitution-like pieces of
information: 'soe_subst' (from InVar to OutExpr) and 'soe_inl'
(from InId to InExpr). It is thus incorrect to have 'pushCoercionIntoLambda'
apply the substitution from 'soe_subst' while discarding 'soe_inl'
entirely, which is what was done in 15b311be.
Instead, we change back pushCoercionIntoLambda to take an InScopeSet,
and optimise the lambda before calling 'pushCoercionIntoLambda' to avoid
mixing InExpr with OutExpr, or mixing two InExpr with different
environments. We can then call 'soeZapSubst' without problems.
Fixes #26588 #26589
-
84a087d5
by Sylvain Henry at 2025-11-28T17:35:28-05:00
Fix PIC jump tables on Windows (#24016)
Avoid overflows in jump tables by using a base label closer to the jump
targets. See added Note [Jump tables]
-
82db7042
by Zubin Duggal at 2025-11-28T17:36:10-05:00
rts/linker/PEi386: Copy strings before they are inserted into LoadedDllCache. The original strings are temporary and might be freed at an arbitrary point.
Fixes #26613
-
ff3f0d09
by Ben Gamari at 2025-11-29T18:34:28-05:00
gitlab-ci: Run ghcup-metadata jobs on OpenCape runners
This significantly reduces our egress traffic
and makes the jobs significantly faster.
-
ef0dc33b
by Matthew Pickering at 2025-11-29T18:35:10-05:00
Use 'OsPath' in getModificationTimeIfExists
This part of the compiler is quite hot during recompilation checking in
particular since the filepaths will be translated to a string. It is
better to use the 'OsPath' native function, which turns out to be easy
to do.
-
fa3bd0a6
by Georgios Karachalias at 2025-11-29T18:36:05-05:00
Use OsPath in PkgDbRef and UnitDatabase, not FilePath
-
0d7c05ec
by Ben Gamari at 2025-12-01T03:13:46-05:00
hadrian: Place user options after package arguments
This makes it easier for the user to override the default package
arguments with `UserSettings.hs`.
Fixes #25821.
-------------------------
Metric Decrease:
T14697
-------------------------
-
3b2c4598
by Vladislav Zavialov at 2025-12-01T03:14:29-05:00
Namespace-specified wildcards in import/export lists (#25901)
This change adds support for top-level namespace-specified wildcards
`type ..` and `data ..` to import and export lists.
Examples:
import M (type ..) -- imports all type and class constructors from M
import M (data ..) -- imports all data constructors and terms from M
module M (type .., f) where
-- exports all type and class constructors defined in M,
-- plus the function 'f'
The primary intended usage of this feature is in combination with module
aliases, allowing namespace disambiguation:
import Data.Proxy as T (type ..) -- T.Proxy is unambiguously the type constructor
import Data.Proxy as D (data ..) -- D.Proxy is unambiguously the data constructor
The patch accounts for the interactions of wildcards with:
* Imports with `hiding` clauses
* Import warnings -Wunused-imports, -Wdodgy-imports
* Export warnings -Wduplicate-exports, -Wdodgy-exports
Summary of the changes:
1. Move the NamespaceSpecifier type from GHC.Hs.Binds to GHC.Hs.Basic,
making it possible to use it in more places in the AST.
2. Extend the AST (type: IE) with a representation of `..`, `type ..`,
and `data ..` (constructor: IEWholeNamespace). Per the proposal, the
plain `..` is always rejected with a dedicated error message.
3. Extend the grammar in Parser.y with productions for `..`, `type ..`,
and `data ..` in both import and export lists.
4. Implement wildcard imports by updating the `filterImports` function
in GHC.Rename.Names; the logic for IEWholeNamespace is roughly
modeled after the Nothing (no explicit import list) case.
5. Implement wildcard exports by updating the `exports_from_avail`
function in GHC.Tc.Gen.Export; the logic for IEWholeNamespace is
closely modeled after the IEModuleContents case.
6. Refactor and extend diagnostics to report the new warnings and
errors. See PsErrPlainWildcardImport, DodgyImportsWildcard,
PsErrPlainWildcardExport, DodgyExportsWildcard,
TcRnDupeWildcardExport.
Note that this patch is specifically about top-level import/export
items. Subordinate import/export items are left unchanged.
-
c71faa76
by Luite Stegeman at 2025-12-01T03:16:05-05:00
rts: Handle overflow of ELF section header string table
If the section header string table is stored in a section greater
than or equal to SHN_LORESERVE (0xff00), the 16-bit field e_shstrndx
in the ELF header does not contain the section number, but rather
an overflow value SHN_XINDEX (0xffff) indicating that we need to look
elsewhere.
This fixes the linker by not using e_shstrndx directly but calling
elf_shstrndx, which correctly handles the SHN_XINDEX value.
Fixes #26603
-
ab20eb54
by Mike Pilgrem at 2025-12-01T22:46:55+00:00
Re CLC issue 292 Warn GHC.Internal.List.{init,last} are partial
Also corrects the warning for `tail` to refer to `Data.List.uncons` (like the existing warning for `head`).
In module `Settings.Warnings`, applies `-Wno-x-partial` to the `filepath`, and `parsec` packages (outside GHC's repository).
Also bumps submodules.
-
fc1d7f79
by Jade Lovelace at 2025-12-02T11:04:09-05:00
docs: fix StandaloneKindSignatures in DataKinds docs
These should be `type` as otherwise GHC reports a duplicate definition
error.
-
beae879b
by Rodrigo Mesquita at 2025-12-03T15:42:37+01:00
task: Substitute some datatypes for newtypes
* Substitutes some data type declarations for newtype declarations
* Adds comment to `LlvmConfigCache`, which must decidedly not be a
newtype.
Fixes #23555
-
3bd7dd44
by mangoiv at 2025-12-04T04:36:45-05:00
Renamer: reinstate the template haskell level check in notFound
Out-of-scope names might be caused by a staging error, as is explained by
Note [Out of scope might be a staging error] in GHC.Tc.Utils.Env.hs.
This logic was assumed to be dead code after 217caad1 and has thus been
removed. This commit reintroduces it and thus fixes issue #26099.
-
0318010b
by Zubin Duggal at 2025-12-04T04:37:27-05:00
testlib: Optionally include the way name in the expected output file
This allows us to have different outputs for different ways.
-
6d945fdd
by Zubin Duggal at 2025-12-04T04:37:27-05:00
testsuite: Accept output of tests failing in ext-interp way due to differing compilation requirements
Fixes #26552
-
0ffc5243
by Cheng Shao at 2025-12-04T04:38:09-05:00
devx: minor fixes for compile_flags.txt
This patch includes minor fixes for compile_flags.txt to improve
developer experience when using clangd as language server to hack on
RTS C sources:
- Ensure `-fPIC` is passed and `__PIC__` is defined, to be coherent
with `-DDYNAMIC` and ensure the `__PIC__` guarded code paths are
indexed
- Add the missing `-DRtsWay` definition, otherwise a few source files
like `RtsUtils.c` and `Trace.c` would produce clangd errors
-
e36a5fcb
by Matthew Pickering at 2025-12-05T16:25:57-05:00
Add support for building bytecode libraries
A bytecode library is a collection of bytecode files (.gbc) and a
library which combines together additional object files.
A bytecode library is created by invoking GHC with the `-bytecodelib`
flag.
A library can be created from in-memory `ModuleByteCode` linkables or
by passing `.gbc` files as arguments on the command line.
Fixes #26298
-
8f9ae339
by Matthew Pickering at 2025-12-05T16:25:57-05:00
Load bytecode libraries to satisfy package dependencies
This commit allows you to use a bytecode library to satisfy a package
dependency when using the interpreter.
If a user enables `-fprefer-byte-code`, then if a package provides a
bytecode library, that will be loaded and used to satisfy the
dependency.
The main change is to separate the relevant parts of the `LoaderState`
into external and home package byte code. Bytecode is loaded into either
the home package or external part (similar to HPT/EPS split), HPT
bytecode can be unloaded. External bytecode is never unloaded.
The unload function has also only been called with an empty list of
"stable linkables" for a long time. It has been modified to directly
implement a complete unloading of the home package bytecode linkables.
At the moment, the bytecode libraries are found in the "library-dirs"
field from the package description. In the future when `Cabal`
implements support for "bytecode-library-dirs" field, we can read the
bytecode libraries from there. No changes to the Cabal submodule are
necessary at the moment.
Four new tests are added in testsuite/tests/cabal, which generate fake
package descriptions and test loading the libraries into GHCi.
Fixes #26298
-
54458ce4
by mangoiv at 2025-12-05T16:26:50-05:00
ExplicitLevelImports: improve documentation of the code
- more explicit names for variable names like `flg` or `topLevel`
- don't pass the same value twice to functions
- some explanations of interesting but undocumented code paths
- adjust comment to not mention non-existent error message
-
c7061392
by mangoiv at 2025-12-05T16:27:42-05:00
driver: don't expect nodes to exist when checking paths between them
In `mgQueryZero`, previously node lookups were expected to never fail,
i.e. it was expected that when calculating the path between two nodes in
a zero level import graph, both nodes would always exist. This is not
the case, e.g. in some situations involving exact names (see the
test-case). The fix is to first check whether the node is present in the
graph at all, instead of panicking, just to report that there is no
path.
Closes #26568
-
d6cf8463
by Peng Fan at 2025-12-06T11:06:28-05:00
NCG/LA64: Simplify genCCall into two parts
genCCall is too long, so it's been simplified into two parts:
genPrim and genLibCCall.
Suggested by Andreas Klebinger
-
9d371d23
by Matthew Pickering at 2025-12-06T11:07:09-05:00
hadrian: Use a response file to invoke GHC for dep gathering.
In some cases we construct an argument list too long for GHC to
handle directly on windows. This happens when we generate
the dependency file because the command line will contain
references to a large number of .hs files.
To avoid this we now invoke GHC using a response file when
generating dependencies to sidestep length limitations.
Note that we only pass the actual file names in the dependency
file. Why? Because this side-steps #26560
-
0043bfb0
by Marc Scholten at 2025-12-06T11:08:03-05:00
update xhtml to 3000.4.0.0
haddock-api: bump xhtml bounds
haddock-api: use lazy text instead of string to support xhtml 3000.4.0.0
Bumping submodule xhtml to 3000.4.0.0
add xhtml to stage0Packages
remove unused import of writeUtf8File
Remove redundant import
Update haddock golden files for xhtml 3000.4.0.0
Metric Decrease:
haddock.Cabal
haddock.base
-
fc958fc9
by Julian Ospald at 2025-12-06T11:08:53-05:00
rts: Fix object file format detection in loadArchive
Commit 76d1041dfa4b96108cfdd22b07f2b3feb424dcbe seems to
have introduced this bug, ultimately leading to failure of
test T11788. I can only theorize that this test isn't run
in upstream's CI, because they don't build a static GHC.
The culprit is that we go through the thin archive, trying
to follow the members on the filesystem, but don't
re-identify the new object format of the member. This pins
`object_fmt` to `NotObject` from the thin archive.
Thanks to @angerman for spotting this.
-
0f297f6e
by mangoiv at 2025-12-06T11:09:44-05:00
users' guide: don't use f strings in the python script to ensure compatibility with python 3.5
-
3bfe7aa2
by Matthew Pickering at 2025-12-07T12:18:57-05:00
ci: Try using multi repl in ghc-in-ghci test
This should be quite a bit faster than the ./hadrian/ghci command as it
doesn't properly build all the dependencies.
-
2ef1601a
by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00
Stack.Decode: Don't error on bitmap size 0
A RET_BCO may have a bitmap with no payload.
In that case, the bitmap = 0.
One can observe this by using -ddump-bcos and interpreting
```
main = pure ()
```
Observe, for instance, that the BCO for this main function has size 0:
```
ProtoBCO Main.main#0:
\u []
break<main:Main,0>() GHC.Internal.Base.pure
GHC.Internal.Base.$fApplicativeIO GHC.Internal.Tuple.()
bitmap: 0 []
BRK_FUN <breakarray> main:Main 0 <cc>
PACK () 0
PUSH_G GHC.Internal.Base.$fApplicativeIO
PUSH_APPLY_PP
PUSH_G GHC.Internal.Base.pure
ENTER
```
Perhaps we never tried to decode a stack in which a BCO like this was
present. However, for the debugger, we want to decode stacks of threads
stopped at breakpoints, and these kind of BCOs do get on a stack under
e.g. `stg_apply_interp_info` frames.
See the accompanying test in the next commit for an example to trigger
the bug this commit fixes.
Fixes #26640
-
747153d2
by Rodrigo Mesquita at 2025-12-07T12:19:38-05:00
Add test for #26640
-
d4b1e353
by Simon Hengel at 2025-12-10T00:00:02-05:00
Fix syntax error in gadt_syntax.rst
-
91cc8be6
by Cheng Shao at 2025-12-10T00:00:43-05:00
ci: fix "ci.sh clean" to address frequent out of space error on windows runners
This patch fixes the `ci.sh clean` logic to address frequent out of
space error on windows runners; previously it didn't clean up the
inplace mingw blobs, which is the largest source of space leak on
windows runners. See added comment for detailed explanation.
-
fe2b79f4
by Recursion Ninja at 2025-12-10T08:34:18-05:00
Narrow before optimising MUL/DIV/REM into shifts
The MUL/DIV/REM operations can be optimised into shifts when one of the
operands is a constant power of 2. However, as literals in Cmm are
stored as 'Integer', for this to be correct we first need to narrow the
literal to the appropriate width before checking whether the literal is
a power of 2.
Fixes #25664
-
06c2349c
by Recursion Ninja at 2025-12-10T08:34:58-05:00
Decouple 'Language.Haskell.Syntax.Type' from 'GHC.Utils.Panic'
- Remove the *original* defintion of 'hsQTvExplicit' defined within 'Language.Haskell.Syntax.Type'
- Redefine 'hsQTvExplicit' as 'hsq_explicit' specialized to 'GhcPass' exported by 'GHC.Utils.Panic'
- Define 'hsQTvExplicitBinders' as 'hsq_explicit' specialized to 'DocNameI' exported by 'Haddock.GhcUtils'.
- Replace all call sites of the original 'hsQTvExplicit' definition with either:
1. 'hsQTvExplicit' updated definition
2. 'hsQTvExplicitBinders'
All call sites never entered the 'XLHsQTyVars' constructor branch, but a call to 'panic' existed on this code path because the type system was not strong enought to guarantee that the 'XLHsQTyVars' construction was impossible.
These two specialized functions provide the type system with enough information to make that guarantee, and hence the dependancy on 'panic' can be removed.
-
ac0815d5
by sheaf at 2025-12-10T23:39:57-05:00
Quantify arg before mult in function arrows
As noted in #23764, we expect quantification order to be left-to-right,
so that in a type such as
a %m -> b
the inferred quantification order should be [a, m, b] and not [m, a, b].
This was addressed in commit d31fbf6c, but that commit failed to update
some other functions such as GHC.Core.TyCo.FVs.tyCoFVsOfType.
This affects Haddock, as whether we print an explicit forall or not
depends on whether the inferred quantification order matches the actual
quantification order.
-
2caf796e
by sheaf at 2025-12-10T23:39:57-05:00
Haddock: improvements to ty-var quantification
This commit makes several improvements to how Haddock deals with the
quantification of type variables:
1. In pattern synonyms, Haddock used to jumble up universal and
existential quantification. That is now fixed, fixing #26252.
Tested in the 'PatternSyns2' haddock-html test.
2. The logic for computing whether to use an explicit kind annotation
for a type variable quantified in a forall was not even wrong.
This commit improves the heuristic, but it will always remain an
imperfect heuristic (lest we actually run kind inference again).
In the future (#26271), we hope to avoid reliance on this heuristic.
-
b14bdd59
by Teo Camarasu at 2025-12-10T23:40:38-05:00
Add explicit export list to GHC.Num
Let's make clear what this module exports to allow us to easily deprecate and remove some of these in the future. Resolves https://gitlab.haskell.org/ghc/ghc/-/issues/26625
-
d99f8326
by Cheng Shao at 2025-12-11T19:14:18-05:00
compiler: remove unused CPP code in foreign stub
This patch removes unused CPP code in the generated foreign stub:
- `#define IN_STG_CODE 0` is not needed, since `Rts.h` already
includes this definition
- The `if defined(__cplusplus)` code paths are not needed in the `.c`
file, since we don't generate C++ stubs and don't include C++
headers in our stubs. But it still needs to be present in the `.h`
header since it might be later included into C++ source files.
-
46c9746f
by Cheng Shao at 2025-12-11T19:14:57-05:00
configure: bump LlvmMaxVersion to 22
This commit bumps LlvmMaxVersion to 22; 21.x releases have been
available since Aug 26th, 2025 and there's no regressions with 21.x so
far. This bump is also required for updating fedora image to 43.
-
96fce8d0
by Cheng Shao at 2025-12-12T01:17:51+01:00
hadrian: add support for building with UndefinedBehaviorSanitizer
This patch adds a +ubsan flavour transformer to hadrian to build all
stage1+ C/C++ code with UndefinedBehaviorSanitizer. This is
particularly useful to catch potential undefined behavior in the RTS
codebase.
-
f7a06d8c
by Cheng Shao at 2025-12-12T01:17:51+01:00
ci: update alpine/fedora & add ubsan job
This patch updates alpine image to 3.23, fedora image to 43, and adds
a `x86_64-linux-fedora43-validate+debug_info+ubsan` job that's run in
validate/nightly pipelines to catch undefined behavior in the RTS
codebase.
-
2ccd11ca
by Cheng Shao at 2025-12-12T01:17:51+01:00
rts: fix zero-length VLA undefined behavior in interpretBCO
This commit fixes a zero-length VLA undefined behavior in interpretBCO, caught by UBSan:
```
+rts/Interpreter.c:3133:19: runtime variable length array bound evaluates to non-positive value 0
```
-
4156ed19
by Cheng Shao at 2025-12-12T01:17:51+01:00
rts: fix unaligned ReadSpB in interpretBCO
This commit fixes unaligned ReadSpB in interpretBCO, caught by UBSan:
```
+rts/Interpreter.c:2174:64: runtime load of misaligned address 0x004202059dd1 for type 'StgWord', which requires 8 byte alignment
```
To perform proper unaligned read, we define StgUnalignedWord as a type
alias of StgWord with aligned(1) attribute, and load StgUnalignedWord
instead of StgWord in ReadSpB, so the C compiler is aware that we're
not loading with natural alignment.
-
fef89fb9
by Cheng Shao at 2025-12-12T01:17:51+01:00
rts: fix signed integer overflow in subword arithmetic in interpretBCO
This commit fixes signed integer overflow in subword arithmetic in
interpretBCO, see added note for detailed explanation.
-
3c001377
by Cheng Shao at 2025-12-13T05:03:15-05:00
ci: use treeless fetch for perf notes
This patch improves the ci logic for fetching perf notes by using
treeless fetch
(https://github.blog/open-source/git/get-up-to-speed-with-partial-clone-and-shallow-clone),
to avoid downloading all blobs of the perf notes repo at once, and
only fetch the actually required blobs on-demand when needed. This
makes the initial `test-metrics.sh pull` operation much faster, and
also more robust, since we are seeing an increasing rate of 504 errors
in CI when fetching all perf notes at once, which is a major source of
CI flakiness at this point.
Co-authored-by: Codex <codex@openai.com>
-
123a8d77
by Peter Trommler at 2025-12-13T05:03:57-05:00
Cmm: remove restriction in MachOp folding
-
0b54b5fd
by Andreas Klebinger at 2025-12-13T05:04:38-05:00
Remove explicit Typeable deriviations.
-
08b13f7b
by Cheng Shao at 2025-12-13T05:05:18-05:00
ci: set gc.auto=0 during setup stage
This patch sets `gc.auto=0` during `setup` stage of CI, see added
comment for detailed explanation.
-
3b5aecb5
by Ben Gamari at 2025-12-13T23:43:10+01:00
Bump exceptions submodule to 0.10.11
-
c32de3b0
by Johan Förberg at 2025-12-15T02:36:03-05:00
base: Define Semigroup and Monoid instances for lazy ST
CLC proposal:
https://github.com/haskell/core-libraries-committee/issues/374
Fixes #26581
-
4f8b660c
by mangoiv at 2025-12-15T02:37:05-05:00
ci: do not require nightly cabal-reinstall job to succeed
-
2c2a3ef3
by Cheng Shao at 2025-12-15T11:51:53-05:00
docs: drop obsolete warning about -fexternal-interpreter on windows
This patch drops an obsolete warning about -fexternal-interpreter not
supported on windows; it is supported since a long time ago, including
the profiled way.
-
68573aa5
by Marc Scholten at 2025-12-15T11:53:00-05:00
haddock: Drop Haddock.Backends.HaddockDB as it's unused
-
b230d549
by mangoiv at 2025-12-16T15:17:45-05:00
base: generalize delete{Firsts,}By
When we delete{Firsts,}By we should not require the
lists to be the same type. This is an especially useful
generalisation in the case of deleteFirstsBy because we
can skip an invocation of the map function.
This change was discussed on the core-libraries-committee's bug
tracker at https://github.com/haskell/core-libraries-committee/issues/372.
-
6a2b43e3
by Cheng Shao at 2025-12-16T15:18:30-05:00
compiler: clean up redundant LANGUAGE pragmas
This patch bumps `default-language` of `ghc`/`ghc-bin` from `GHC2021`
to `GHC2024` (which is supported in ghc 9.10, current boot ghc lower
version bound), and also cleans up redundant `LANGUAGE` pragmas (as
well as `default-extensions`/`other-extensions`) that are already
implied by `GHC2024`.
Co-authored-by: Codex <codex@openai.com>
-
fca9cd7c
by sheaf at 2025-12-18T13:18:18-05:00
X86 CodeGen: fix assign_eax_sse_regs
We must set %al to the number of SSE2 registers that contain arguments
(in case we are dealing with a varargs function). The logic for counting
how many arguments reside in SSE2 registers was incorrect, as it used
'isFloatFormat', which incorrectly ignores vector registers.
We now instead do case analysis on the register class:
is_sse_reg r =
case targetClassOfReg platform r of
RcFloatOrVector -> True
RcInteger -> False
This change is necessary to prevent segfaults in T20030_test1j, because
subsequent commits change the format calculations, resulting in vector
formats more often.
-
53150617
by sheaf at 2025-12-18T13:18:19-05:00
X86 regUsageOfInstr: fix format for IMUL
When used with 8-bit operands, the IMUL instruction returns the result
in the lower 16 bits of %rax (also known as %ax). This is different
than for the other sizes, where an input at 16, 32 or 64 bits will
result in 16, 32 or 64 bits of output in both %rax and %rdx.
This doesn't affect the behaviour of the compiler, because we don't
allow partial writes at sub-word sizes. The rationale is explained
in Wrinkle [Don't allow scalar partial writes] in Note [Register formats in liveness analysis],
in GHC.CmmToAsm.Reg.Liveness.
-
c7a56dd1
by sheaf at 2025-12-18T13:18:19-05:00
Liveness analysis: consider register formats
This commit updates the register allocator to be a bit more careful in
situations in which a single register is used at multiple different
formats, e.g. when xmm1 is used both to store a Double# and a DoubleX2#.
This is done by introducing the 'Regs' newtype around 'UniqSet RegWithFormat',
for which the combining operations take the larger of the two formats
instead of overriding the format.
Operations on 'Regs' are defined in 'GHC.CmmToAsm.Reg.Regs'. There is
a modest compile-time cost for the additional overhead for tracking
register formats, which causes the metric increases of this commit.
The subtle aspects of the implementation are outlined in
Note [Register formats in liveness analysis] in GHC.CmmToAsm.Reg.Liveness.
Fixes #26411 #26611
-------------------------
Metric Increase:
T12707
T26425
T3294
-------------------------
-
c2e83339
by sheaf at 2025-12-18T13:18:19-05:00
Register allocator: reload at same format as spill
This commit ensures that if we spill a register onto the stack at a
given format, we then always reload the register at this same format.
This ensures we don't end up in a situation where we spill F64x2 but end
up only reloading the lower F64. This first reload would make us believe
the whole data is in a register, thus silently losing the upper 64 bits
of the spilled register's contents.
Fixes #26526
-
55ab583b
by sheaf at 2025-12-18T13:18:19-05:00
Register allocation: writes redefine format
As explained in Note [Allocated register formats] in GHC.CmmToAsm.Reg.Linear,
we consider all writes to redefine the format of the register.
This ensures that in a situation such as
movsd .Ln6m(%rip),%v1
shufpd $0,%v1,%v1
we properly consider the broadcast operation to change the format of %v1
from F64 to F64x2.
This completes the fix to #26411 (test in T26411b).
-
951402ed
by Vladislav Zavialov at 2025-12-18T13:19:05-05:00
Parser: improve mkModuleImpExp, remove checkImportSpec
1. The `mkModuleImpExp` helper now knows whether it is processing an import or
export list item, and uses this information to produce a more accurate error
message for `import M (T(..,x))` with PatternSynonyms disabled.
The old message incorrectly referred to this case as an export form.
2. The `checkImportSpec` helper is removed in favor of more comprehensive error
checking in `mkModuleImpExp`.
3. Additionaly, the invariants of `ImpExpList` and `ImpExpAllWith` have been
made more explicit in the comments and assertions (calls to 'panic').
Test case: import-syntax-no-ext
-
47d83d96
by Vladislav Zavialov at 2025-12-18T13:19:06-05:00
Subordinate namespace-specified wildcards (#25901)
Add support for subordinate namespace-specified wildcards
`X(type ..)` and `X(data ..)` to import and export lists.
Examples:
import M (Cls(type ..)) -- imports Cls and all its associated types
import M (Cls(data ..)) -- imports Cls and all its methods
module M (R(data ..), C(type ..)) where
-- exports R and all its data constructors and record fields;
-- exports C and all its associated types, but not its methods
The scope of this change is limited to the case where the wildcard is the only
subordinate import/export item, whereas the more complex forms `X(type .., f)`
or `X(type .., data ..)` are unsupported and raise the newly introduced
PsErrUnsupportedExplicitNamespace error. This restriction may be lifted later.
Summary of the changes:
1. Refactor IEThingAll to store its extension field XIEThingAll as a record
IEThingAllExt instead of a tuple.
2. Extend the AST by adding a NamespaceSpecifier field to IEThingAllExt,
representing an optional namespace specifier `type` or `data` in front
of a subordinate wildcard `X(..)`.
3. Extend the grammar in Parser.y with productions for `type ..` and `data ..`
in subordinate import/export items.
4. Introduce `filterByNamespaceGREs` to filter [GlobalRdrElt] by a
NamespaceSpecifier; use it in `filterImports` and `exports_from_avail`
to account for the namespace specifier in IEThingAll.
5. Improve diagnostics by storing more information in DodgyImportsEmptyParent
and DodgyExportsEmptyParent.
Test cases:
T25901_sub_e T25901_sub_f T25901_sub_g T25901_sub_a
T25901_sub_b T25901_sub_c T25901_sub_d T25901_sub_w
DodgyImports02 DodgyImports03 DodgyImports04
-
eac418bb
by Recursion Ninja at 2025-12-18T13:19:48-05:00
Removing the 'Data' instance for 'InstEnv'.
The 'Data' instance is blocking work on Trees that Grow, and the
'Data' instance seem to have been added without a clear purpose.
-
e920e038
by Recursion Ninja at 2025-12-18T13:19:48-05:00
'Decouple Language.Haskell.Syntax.Decls' from 'GHC.Unit.Module.Warnings'
-
bd38b76c
by Cheng Shao at 2025-12-18T13:20:31-05:00
testsuite: improve coverage of foundation test
This patch refactors the `foundation` test a bit to improve coverage:
- Instead of using a hard-coded seed, a random seed is now taken from
the command line, and printed upon test failure. This improves test
coverage over many future CI runs, and shall a failure occur, the
seed is available in the CI log for local reproduction.
- The iterations count is bumped to 1000 instead of 100, similar to
the bump in `test-primops`. Runtime timeout is bumped 2x just to be
safe.
- Improve `newLCGGen` by using non-atomic loads/stores on a
`MutableByteArray#` for storing mutable `Word64`, this test doesn't
use parallelism in the first place
- Fixed a few compiler warnings and removed redundant pragmas and
imports
Co-authored-by: Codex <codex@openai.com>
-
3995187c
by Sylvain Henry at 2025-12-18T13:21:45-05:00
Doc: document -pgmi "" (#26634)
-
5729418c
by Cheng Shao at 2025-12-18T13:22:29-05:00
rts: use __builtin_mul_overflow for hs_mulIntMayOflo
This patch uses `__builtin_mul_overflow` to implement
`hs_mulIntMayOflo`. This is a GNU C checked arithmetic builtin
function supported by gcc/clang, is type-generic so works for both
32-bit/64-bit, and makes the code both more efficient and easier to
read/maintain than the previous hand rolled logic.
-
1ca4b49a
by Cheng Shao at 2025-12-18T13:23:11-05:00
compiler/rts: fix ABI mismatch in barf() invocations
This patch fixes a long-standing issue of ABI mismatch in `barf()`
invocations, both in compiler-emitted code and in hand written Cmm
code:
- In RTS, we have `barf()` which reports a fatal internal error
message and exits the program.
- `barf()` is a variadic C function! When used as a callee of a
foreign call with `ccall` calling convention instead of `capi`,
there is an ABI mismatch between the caller and the callee!
- Unfortunately, both the compiler and the Cmm sources contain many
places where we call `barf()` via `ccall` convention!! Like, when
you write `foreign "C" barf("foo object (%p) entered!", R1)`, it
totally doesn't do what you think it'll do at all!! The second
argument `R1` is not properly passed in `va_list`, and the behavior
is completely undefined!!
- Even more unfortunately, this issue has been sitting around long
enough because the ABI mismatch is subtle enough on normie platforms
like x64 and arm64.
- But there are platforms like wasm32 that are stricter about ABI, and
the broken `barf()` invocations already causes trouble for wasm
backend: we had to use ugly hacks like `barf(errmsg, NULL)` to make
`wasm-ld` happy, and even with this band-aid, compiler-generated
`barf()` invocations are still broken, resulting in regressions in
certain debug-related functionality, e.g. `-dtag-inference-checks`
is broken on wasm32 (#22882).
This patch properly fixes the issue:
- We add non-variadic `barf` wrappers in the RTS that can be used as
`ccall` callees
- Both the compiler `emitBarf` logic and the hand-written Cmm are
changed to call these wrappers
- `emitBarf` now also properly annotates the foreign call as
`CmmNeverReturns` to indicate it's a noreturn call to enable more
efficient code generation
`-dtag-inference-checks` now works on wasm. Closes #22882.
Co-authored-by: Codex <codex@openai.com>
-
b3dd23b9
by Vilim Lendvaj at 2025-12-18T13:23:57-05:00
Remove outdated comment
The Traversable instance for ZipList is no longer in
GHC.Internal.Data.Traversable. In fact, it is right below this very comment.
-
9a9c2f03
by Cheng Shao at 2025-12-18T13:24:39-05:00
compiler: remove unused OtherSection logic
This patch removes the OtherSection logic in Cmm, given it's never
actually used by any of our backends.
-
91edd292
by Wolfgang Jeltsch at 2025-12-19T03:18:19-05:00
Remove unused known-key and name variables for generics
This removes the known-key and corresponding name variables for `K1`,
`M1`, `R`, `D`, `C`, `S`, and `URec` from `GHC.Generics`, as they are
apparently nowhere used in GHC’s source code.
-
73ee7e38
by Wolfgang Jeltsch at 2025-12-19T03:19:02-05:00
Remove unused known keys and names for generics classes
This removes the known-key and corresponding name variables for
`Datatype`, `Constructor`, and `Selector` from `GHC.Generics`, as they
are apparently nowhere used in GHC’s source code.
-
f69c5f14
by Cheng Shao at 2025-12-19T03:19:45-05:00
wasm: fix handling of ByteArray#/MutableByteArray# arguments in JSFFI imports
This patch fixes the handling of ByteArray#/MutableByteArray#
arguments in JSFFI imports, see the amended note and manual for
explanation. Also adds a test to witness the fix.
Co-authored-by: Codex <codex@openai.com>
-
224446a2
by Cheng Shao at 2025-12-20T07:49:54-05:00
rts: workaround -Werror=maybe-uninitialized false positives
In some cases gcc might report -Werror=maybe-uninitialized that we
know are false positives, but need to workaround it to make validate
builds with -Werror pass.
-
251ec087
by Cheng Shao at 2025-12-20T07:49:54-05:00
hadrian: use -Og as C/C++ optimization level when debugging
This commit enables -Og as optimization level when compiling the debug
ways of rts. According to gcc documentation
(https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-Og),
-Og is a better choice than -O0 for producing debuggable code. It's
also supported by clang as well, so it makes sense to use it as a
default for debugging. Also add missing -g3 flag to C++ compilation
flags in +debug_info flavour transformer.
-
fb586c67
by Cheng Shao at 2025-12-20T07:50:36-05:00
compiler: replace DList with OrdList
This patch removes `DList` logic from the compiler and replaces it
with `OrdList` which also supports O(1) concatenation and should be
more memory efficient than the church-encoded `DList`.
-
8149c987
by Cheng Shao at 2025-12-20T17:06:51-05:00
hadrian: add with_profiled_libs flavour transformer
This patch adds a `with_profiled_libs` flavour transformer to hadrian
which is the exact opposite of `no_profiled_libs`. It adds profiling
ways to stage1+ rts/library ways, and doesn't alter other flavour
settings. It is useful when needing to test profiling logic locally
with a quick flavour.
-
746b18cd
by Cheng Shao at 2025-12-20T17:06:51-05:00
hadrian: fix missing profiled dynamic libraries in profiled_ghc
This commit fixes the profiled_ghc flavour transformer to include
profiled dynamic libraries as well, since they're supported by GHC
since !12595.
-
4dd7e3b9
by Cheng Shao at 2025-12-20T17:07:33-05:00
ci: set http.postBuffer to mitigate perf notes timeout on some runners
This patch sets http.postBuffer to mitigate the timeout when fetching
perf notes on some runners with slow internet connection. Fixes #26684.
-
bc36268a
by Wolfgang Jeltsch at 2025-12-21T16:23:24-05:00
Remove unused known keys and names for type representations
This removes the known-key and corresponding name variables for
`TrName`, `TrNameD`, `TypeRep`, `KindRepTypeLitD`, `TypeLitSort`, and
`mkTrType`, as they are apparently nowhere used in GHC’s source code.
-
ff5050e9
by Wolfgang Jeltsch at 2025-12-21T16:24:04-05:00
Remove unused known keys and names for natural operations
This removes the known-key and corresponding name variables for
`naturalAndNot`, `naturalLog2`, `naturalLogBaseWord`, `naturalLogBase`,
`naturalPowMod`, `naturalSizeInBase`, `naturalToFloat`, and
`naturalToDouble`, as they are apparently nowhere used in GHC’s source
code.
-
424388c2
by Wolfgang Jeltsch at 2025-12-21T16:24:45-05:00
Remove the unused known key and name for `Fingerprint`
This removes the variables for the known key and the name of the
`Fingerprint` data constructor, as they are apparently nowhere used in
GHC’s source code.
-
a1ed86fe
by Wolfgang Jeltsch at 2025-12-21T16:25:26-05:00
Remove the unused known key and name for `failIO`
This removes the variables for the known key and the name of the
`failIO` operation, as they are apparently nowhere used in GHC’s source
code.
-
b8220daf
by Wolfgang Jeltsch at 2025-12-21T16:26:07-05:00
Remove the unused known key and name for `liftM`
This removes the variables for the known key and the name of the `liftM`
operation, as they are apparently nowhere used in GHC’s source code.
-
eb0628b1
by Wolfgang Jeltsch at 2025-12-21T16:26:47-05:00
Fix the documentation of `hIsClosed`
-
db1ce858
by sheaf at 2025-12-22T17:11:17-05:00
Do deep subsumption when computing valid hole fits
This commit makes a couple of improvements to the code that
computes "valid hole fits":
1. It uses deep subsumption for data constructors.
This matches up the multiplicities, as per
Note [Typechecking data constructors].
This fixes #26338 (test: LinearHoleFits).
2. It now suggests (non-unidirectional) pattern synonyms as valid
hole fits. This fixes #26339 (test: PatSynHoleFit).
3. It uses 'stableNameCmp', to make the hole fit output deterministic.
-------------------------
Metric Increase:
hard_hole_fits
-------------------------
-
72ee9100
by sheaf at 2025-12-22T17:11:17-05:00
Speed up hole fits with a quick pre-test
This speeds up the machinery for valid hole fits by doing a small
check to rule out obviously wrong hole fits, such as:
1. A hole fit identifier whose type has a different TyCon at the head,
after looking through foralls and (=>) arrows, e.g.:
hole_ty = Int
cand_ty = Maybe a
or
hole_ty = forall a b. a -> b
cand_ty = forall x y. Either x y
2. A hole fit identifier that is not polymorphic when the hole type
is polymorphic, e.g.
hole_ty = forall a. a -> a
cand_ty = Int -> Int
-------------------------
Metric Decrease:
hard_hole_fits
-------------------------
-
30e513ba
by Cheng Shao at 2025-12-22T17:12:00-05:00
configure: remove unused win32-tarballs.md5sum
This patch removes the unused `win32-tarballs.md5sum` file from the
tree. The current mingw tarball download logic in
`mk/get-win32-tarballs.py` fetches and checks against `SHA256SUM` from
the same location where the tarballs are fetched, and this file has
been unused for a few years.
-
a2d52b3b
by Wolfgang Jeltsch at 2025-12-23T04:47:33-05:00
Add an operation `System.IO.hGetNewlineMode`
This commit also contains some small code and documentation changes for
related operations, for the sake of consistency.
-
b26d134a
by Cheng Shao at 2025-12-23T04:48:15-05:00
rts: opportunistically reclaim slop space in shrinkMutableByteArray#
Previously, `shrinkMutableByteArray#` shrinks a `MutableByteArray#`
in-place by assigning the new size to it, and zeroing the extra slop
space. That slop space is not reclaimed and wasted. But it's often the
case that we allocate a `MutableByteArray#` upfront, then shrink it
shortly after, so the `MutableByteArray#` closure sits right at the
end of a nursery block; this patch identifies such chances, and also
shrink `bd->free` if possible, reducing heap space fragmentation.
Co-authored-by: Codex <codex@openai.com>
-------------------------
Metric Decrease:
T10678
-------------------------
-
c72ddabf
by Cheng Shao at 2025-12-23T16:13:23-05:00
hadrian: fix bootstrapping with ghc-9.14
This patch fixes bootstrapping GHC with ghc-9.14, tested locally with
ghc-9.14.1 release as bootstrapping GHC.
-
0fd6d8e4
by Cheng Shao at 2025-12-23T16:14:05-05:00
hadrian: pass -keep-tmp-files to test ghc when --keep-test-files is enabled
This patch makes hadrian pass `-keep-tmp-files` to test ghc when
`--keep-test-files` is enabled, so you can check the ghc intermediate
files when debugging certain test failures. Closes #26688.
-
81d10134
by Cheng Shao at 2025-12-24T06:11:52-05:00
configure: remove dead code in configure scripts
This patch removes dead code in our configure scripts, including:
- Variables and auto-detected programs that are not used
- autoconf functions that are not used, or export a variable that's
not used
- `AC_CHECK_HEADERS` invocations that don't have actual corresponding
`HAVE_XXX_H` usage
- Other dead code (e.g. stray `AC_DEFUN()`)
Co-authored-by: Codex <codex@openai.com>
-
fb1381c3
by Wolfgang Jeltsch at 2025-12-24T06:12:34-05:00
Remove unused known keys and names for list operations
This removes the known-key and corresponding name variables for
`concat`, `filter`, `zip`, and `(++)`, as they are apparently nowhere
used in GHC’s source code.
-
7b9c20f4
by Recursion Ninja at 2025-12-24T10:35:36-05:00
Decoupling Language.Haskell.Syntax.Binds from GHC.Types.Basic
by transferring InlinePragma types between the modules.
* Moved InlinePragma data-types to Language.Haskell.Syntax.Binds.InlinePragma
* Partitioned of Arity type synonyms to GHC.Types.Arity
* InlinePragma is now extensible via Trees That Grow
* Activation is now extensible via Trees That Grow
* Maybe Arity change to more descriptive InlineSaturation data-type
* InlineSaturation information removed from InlinePragma during GHS parsing pass
* Cleaned up the exposed module interfaces of the new modules
-
a3afae0c
by Simon Peyton Jones at 2025-12-25T15:26:36-05:00
Check for rubbish literals in Lint
Addresses #26607.
See new Note [Checking for rubbish literals] in GHC.Core.Lint
-
8a317b6f
by Aaron Allen at 2026-01-01T03:05:15-05:00
[#26183] Associated Type Iface Fix
When determining "extras" for class decl interface entries, axioms for
the associated types need to included so that dependent modules will be
recompiled if those axioms change.
resolves #26183
-
ae1aeaab
by Cheng Shao at 2026-01-01T03:06:32-05:00
testsuite: run numeric tests with optasm when available
This patch adds the `optasm` extra way to nueric tests when NCG is
available. Some numeric bugs only surface with optimization, omitting
this can hide these bugs and even make them slip into release! (e.g. #26711)
-
6213bb57
by maralorn at 2026-01-02T16:30:32+01:00
GHC.Internal.Exception.Context: Fix comment
on addExceptionAnnotation
-
b820ff50
by Janis Voigtlaender at 2026-01-05T02:43:18-05:00
GHC.Internal.Control.Monad.replicateM: Fix comment
-
a8a94aad
by Cheng Shao at 2026-01-05T16:24:04-05:00
hadrian: drops unused PE linker script for windows
This patch drops unused PE linker script for windows in the
`MergeObjects` builder of hadrian. The linker script is used for
merging object files into a single `HS*.o` object file and undoing the
effect of split sections, when building the "ghci library" object
file. However, we don't build the ghci library on windows, and this
code path is actually unreachable.
-
53038ea9
by Cheng Shao at 2026-01-05T16:24:04-05:00
hadrian: drop unused logic for building ghci libraries
This patch drops the unused logic for building ghci libraries in
hadrian:
- The term "ghci library" refers to an optional object file per
library `HS*.o`, which is merged from multiple object files in that
library using the `MergeObjects` builder in hadrian.
- The original rationale of having a ghci library object, in addition
to normal archives, was to speedup ghci loading, since the combined
object is linked with a linker script to undo the effects of
`-fsplit-sections` to reduce section count and make it easier for
the RTS linker to handle.
- However, most GHC builds enable `dynamicGhcPrograms` by default, in
such cases the ghci library would already not be built.
- `dynamicGhcPrograms` is disabled on Windows, but still we don't
build the ghci library due to lack of functioning merge objects
command.
- The only case that we actually build ghci library objects, are
alpine fully static bindists. However, for other reasons, split
sections is already disabled for fully static builds anyway!
- There will not be any regression if the ghci library objects are
absent from a GHC global libdir when `dynamicGhcPrograms` is
disabled. The RTS linker can already load the archives without any
issue.
Hence the removal. We now forcibly disable ghci libraries for all
Cabal components, and rip out all logic related to `MergeObjects` and
ghci libraries in hadrian. This also nicely cleans up some old todos
and fixmes that are no longer relevant.
Note that MergeObjects in hadrian is not the same thing as merge
objects in the GHC driver. The latter is not affected by this patch.
-------------------------
Metric Decrease:
libdir
-------------------------
Co-authored-by: Codex <codex@openai.com>
-
8f209336
by Simon Jakobi at 2026-01-05T16:24:48-05:00
User's guide: Fix link to language extensions
Instead of linking to haddocks, it seemed more useful to link
to the extension overview in the user's guide.
Closes #26614.
-
0b7df6db
by Simon Peyton Jones at 2026-01-06T09:32:23-05:00
Improved fundeps for closed type families
The big payload of this commit is to execute the plan suggested
in #23162, by improving the way that we generate functional
dependencies for closed type families.
It is all described in Note [Exploiting closed type families]
Most of the changes are in GHC.Tc.Solver.FunDeps
Other small changes
* GHC.Tc.Solver.bumpReductionDepth. This function brings together the code that
* Bumps the depth
* Checks for overflow
Previously the two were separated, sometimes quite widely.
* GHC.Core.Unify.niFixSubst: minor improvement, removing an unnecessary
itraetion in the base case.
* GHC.Core.Unify: no need to pass an InScopeSet to
tcUnifyTysForInjectivity. It can calculate one for itself; and it is
never inspected anyway so it's free to do so.
* GHC.Tc.Errors.Ppr: slight impovement to the error message for
reduction-stack overflow, when a constraint (rather than a type) is
involved.
* GHC.Tc.Solver.Monad.wrapUnifier: small change to the API
-
fde8bd88
by Simon Peyton Jones at 2026-01-06T09:32:23-05:00
Add missing (KK4) to kick-out criteria
There was a missing case in kick-out that meant we could fail
to solve an eminently-solvable constraint.
See the new notes about (KK4)
-
00082844
by Simon Peyton Jones at 2026-01-06T09:32:23-05:00
Some small refactorings of error reporting in the typechecker
This is just a tidy-up commit.
* Add ei_insoluble to ErrorItem, to cache insolubility.
Small tidy-up.
* Remove `is_ip` and `mkIPErr` from GHC.Tc.Errors; instead enhance mkDictErr
to handle implicit parameters. Small refactor.
-
fe4cb252
by Simon Peyton Jones at 2026-01-06T09:32:24-05:00
Improve recording of insolubility for fundeps
This commit addresses #22652, by recording when the fundeps for
a constraint are definitely insoluble. That in turn improves the
perspicacity of the pattern-match overlap checker.
See Note [Insoluble fundeps]
-
df0ffaa5
by Simon Peyton Jones at 2026-01-06T09:32:24-05:00
Fix a buglet in niFixSubst
The MR of which this is part failed an assertion check extendTvSubst
because we extended the TvSubst with a CoVar. Boo.
This tiny patch fixes it, and adds the regression test from #13882
that showed it up.
-
3d6aba77
by konsumlamm at 2026-01-06T09:33:16-05:00
Fix changelog formatting
-
69e0ab59
by Cheng Shao at 2026-01-06T19:37:56-05:00
compiler: add targetHasRTSWays function
This commit adds a `targetHasRTSWays` util function in
`GHC.Driver.Session` to query if the target RTS has a given Ways (e.g.
WayThreaded).
-
25a0ab94
by Cheng Shao at 2026-01-06T19:37:56-05:00
compiler: link on-demand external interpreter with threaded RTS
This commit makes the compiler link the on-demand external interpreter
program with threaded RTS if it is available in the target RTS ways.
This is a better default than the previous single-threaded RTS, and it
enables the external interpreter to benefit from parallelism when
deserializing CreateBCOs messages.
-
92404a2b
by Cheng Shao at 2026-01-06T19:37:56-05:00
hadrian: link iserv with threaded RTS
This commit makes hadrian link iserv with threaded RTS if it's
available in the RTS ways. Also cleans up the iserv main C program
which can be replaced by the `-fkeep-cafs` link-time option.
-
a20542d2
by Cheng Shao at 2026-01-06T19:38:38-05:00
ghc-internal: remove unused GMP macros
This patch removes unused GMP related macros from `ghc-internal`. The
in-tree GMP version was hard coded and outdated, but it was not used
anywhere anyway.
-
4079dcd6
by Cheng Shao at 2026-01-06T19:38:38-05:00
hadrian: fix in-tree gmp configure error on newer c compilers
Building in-tree gmp on newer c compilers that default to c23 fails at
configure stage, this patch fixes it, see added comment for
explanation.
-
414d1fe1
by Cheng Shao at 2026-01-06T19:39:20-05:00
compiler: fix LLVM backend pdep/pext handling for i386 target
This patch fixes LLVM backend's pdep/pext handling for i386 target,
and also removes non-existent 128/256/512 bit hs_pdep/hs_pext callees.
See amended note for more explanation. Fixes #26450.
Co-authored-by: Codex <codex@openai.com>
-
c7f6fba3
by Cheng Shao at 2026-01-06T19:39:20-05:00
ci: remove allow_failure flag for i386 alpine job
The LLVM codegen issue for i386 has been fixed, and the i386 alpine
job should pass now. This commit removes the allow_failure flag so
that other i386 regressions in the future are signaled more timely.
-
52d00c05
by Simon Peyton Jones at 2026-01-07T10:24:21-05:00
Add missing InVar->OutVar lookup in SetLevels
As #26681 showed, the SetLevels pass was failing to map an InVar to
an OutVar. Very silly! I'm amazed it hasn't broken before now.
I have improved the type singatures (to mention InVar and OutVar)
so it's more obvious what needs to happen.
-
ab0a5594
by Cheng Shao at 2026-01-07T10:25:04-05:00
hadrian: drop deprecated pkgHashSplitObjs code path
This patch drops deprecated `pkgHashSplitObjs` code path from hadrian,
since GHC itself has removed split objs support many versions ago and
this code path is unused.
-
bb3a2ba1
by Cheng Shao at 2026-01-07T10:25:44-05:00
hadrian: remove linting/assertion in quick-validate flavour
The `quick-validate` flavour is meant for testing ghc and passing the
testsuite locally with similar settings to `validate` but faster. This
patch removes the linting/assertion overhead in `quick-validate` to
improve developer experience. I also took the chance to simplify
redundant logic of rts/library way definition in `validate` flavour.
-
7971f5dd
by Cheng Shao at 2026-01-07T10:26:26-05:00
deriveConstants: clean up unused constants
This patch cleans up unused constants from `deriveConstants`, they are
not used by C/Cmm code in the RTS, nor compiler-generated code.
Co-authored-by: Codex <codex@openai.com>
-
4df96993
by Cheng Shao at 2026-01-07T10:27:08-05:00
hadrian: pass -fno-omit-frame-pointer with +debug_info
This patch adds `-fno-omit-frame-pointer` as C/C++ compilation flag
when compiling with `+debug_info` flavour transformer. It's a sane
default when you care about debugging and reliable backtraces, and
makes debugging/profiling with bpf easier.
-
8a3900a3
by Aaron Allen at 2026-01-07T10:27:57-05:00
[26705] Include TyCl instances in data fam iface entry
Ensures dependent modules are recompiled when the class instances for a
data family instance change.
resolves #26705
-
a0b980af
by Cheng Shao at 2026-01-07T10:28:38-05:00
hadrian: remove unused Hp2Ps/Hpc builders
This patch removes the Hp2Ps/Hpc builders from hadrian, they are
unused in the build system. Note that the hp2ps/hpc programs are still
built and not affected.
-
50a58757
by Cheng Shao at 2026-01-07T10:29:20-05:00
hadrian: only install js files to libdir for wasm/js targets
There are certain js files required for wasm/js targets to work, and
previously hadrian would install those js files to libdir
unconditionally on other targets as well. This could be a minor
annoyance for packagers especially when the unused js files contain
shebangs that interfere with the packaging process. This patch makes
hadrian only selectively install the right js files for the right
targets.
Co-authored-by: Codex <codex@openai.com>
-
da40e553
by Simon Peyton Jones at 2026-01-07T10:30:00-05:00
Add flavour transformer assertions_stage1
This allows us to enable -DDEBUG assertions in the stage1 compiler
-
ec3cf767
by Cheng Shao at 2026-01-08T06:24:31-05:00
make: remove unused Makefiles from legacy make build system
This patch removes unused Makefiles from legacy make build system; now
they are never used by hadrian in any way, and they already include
common boilerplate mk files that are long gone in the make build
system removal, hence the housecleaning.
Co-authored-by: Codex <codex@openai.com>
-
04ea3f83
by Cheng Shao at 2026-01-08T06:25:13-05:00
compiler: use -O3 as LLVM optimization level for ghc -O2
The GHC driver clamps LLVM optimization level to `-O2` due to LLVM
crashes, but those were historical issues many years ago that are no
longer relevant for LLVM versions we support today. This patch changes
the driver to use `-O3` as LLVM optimization level when compiling with
`-O2`, which is a better default when we're willing to trade
compilation time for faster generated code.
-
472df471
by Peter Trommler at 2026-01-08T13:28:54-05:00
Use half-word literals in info tables
With this commit info tables are mapped to the same assembler code
on big-endian and little-endian platforms.
Fixes #26579.
-
393f9c51
by Simon Peyton Jones at 2026-01-08T13:29:35-05:00
Refactor srutOkForBinderSwap
This MR does a small refactor:
* Moves `scrutOkForBinderSwap` and `BinderSwapDecision`
to GHC.Core.Utils
* Inverts the sense of the coercion it returns, which makes
more sense
No effect on behaviour
-
ad76fb0f
by Simon Peyton Jones at 2026-01-08T13:29:36-05:00
Improve case merging
This small MR makes case merging happen a bit more often than
it otherwise could, by getting join points out of the way.
See #26709 and GHC.Core.Utils
Note [Floating join points out of DEFAULT alternatives]
-
4c9395f5
by Cheng Shao at 2026-01-08T13:30:16-05:00
hadrian: remove broken hsc2hs flag when cross compiling to windows
This patch removes the `--via-asm` hsc2hs flag when cross compiling to
windows. With recent llvm-mingw toolchain, it would fail with:
```
x86_64-w64-mingw32-hsc2hs: Cannot combine instructions: [Quad 8,Long 4,Long 241,Ref ".Ltmp1-.Ltmp0"]
```
The hsc2hs default `--cross-compile` logic is slower but works.
-
71fdef55
by Simon Peyton Jones at 2026-01-08T13:30:57-05:00
Try harder to keep the substitution empty
Avoid unnecessary cloning of variables in the Simplifier.
Addresses #26724,
See Note [Keeping the substitution empty]
We get some big wins in compile time
Metrics: compile_time/bytes allocated
-------------------------------------
Baseline
Test Metric value New value Change
----------------------------------------------------------------------------
CoOpt_Singletons(normal) ghc/alloc 721,544,088 692,174,216 -4.1% GOOD
LargeRecord(normal) ghc/alloc 1,268,031,157 1,265,168,448 -0.2%
T14766(normal) ghc/alloc 918,218,533 688,432,296 -25.0% GOOD
T15703(normal) ghc/alloc 318,103,629 306,638,016 -3.6% GOOD
T17836(normal) ghc/alloc 419,174,584 418,400,824 -0.2%
T18478(normal) ghc/alloc 471,042,976 470,261,376 -0.2%
T20261(normal) ghc/alloc 573,387,162 563,663,336 -1.7%
T24984(normal) ghc/alloc 87,832,666 87,636,168 -0.2%
T25196(optasm) ghc/alloc 1,103,284,040 1,101,376,992 -0.2%
hard_hole_fits(normal) ghc/alloc 224,981,413 224,608,208 -0.2%
geo. mean -0.3%
minimum -25.0%
maximum +0.1%
Metric Decrease:
CoOpt_Singletons
T14766
T15703
-
30341168
by Simon Peyton Jones at 2026-01-08T13:31:38-05:00
Add regression test for #24867
-
1ac1a541
by Julian Ospald at 2026-01-09T02:48:53-05:00
Support statically linking executables properly
Fixes #26434
In detail, this does a number of things:
* Makes GHC aware of 'extra-libraries-static' (this changes the package
database format).
* Adds a switch '-static-external' that will honour 'extra-libraries-static'
to link external system dependencies statically.
* Adds a new field to settings/targets: "ld supports verbatim namespace".
This field is used by '-static-external' to conditionally use '-l:foo.a'
syntax during linking, which is more robust than trying to find the
absolute path to an archive on our own.
* Adds a switch '-fully-static' that is meant as a high-level interface
for e.g. cabal. This also honours 'extra-libraries-static'.
This also attempts to clean up the confusion around library search directories.
At the moment, we have 3 types of directories in the package database
format:
* library-dirs
* library-dirs-static
* dynamic-library-dirs
However, we only have two types of linking: dynamic or static. Given the
existing logic in 'mungeDynLibFields', this patch assumes that
'library-dirs' is really just nothing but a fallback and always
prefers the more specific variants if they exist and are non-empty.
Conceptually, we should be ok with even just one search dirs variant.
Haskell libraries are named differently depending on whether they're
static or dynamic, so GHC can conveniently pick the right one depending
on the linking needs. That means we don't really need to play tricks
with search paths to convince the compiler to do linking as we want it.
For system C libraries, the convention has been anyway to place static and
dynamic libs next to each other, so we need to deal with that issue
anyway and it is outside of our control. But this is out of the scope
of this patch.
This patch is backwards compatible with cabal. Cabal should however
be patched to use the new '-fully-static' switch.
-
ad3c808d
by Julian Ospald at 2026-01-09T02:48:53-05:00
Warn when "-dynamic" is mixed with "-staticlib"
-
322dd672
by Matthew Pickering at 2026-01-09T02:49:35-05:00
rts: Use INFO_TABLE_CONSTR for stg_dummy_ret_closure
Since the closure type is CONSTR_NOCAF, we need to use INFO_TABLE_CONSTR
to populate the constructor description field (this crashes ghc-debug
when decoding AP_STACK frames sometimes)
Fixes #26745
-
039bac4c
by Ben Gamari at 2026-01-09T20:22:16-05:00
ghc-internal: Move STM utilities out of GHC.Internal.Conc.Sync
This is necessary to avoid an import cycle on Windows when importing
`GHC.Internal.Exception.Context` in `GHC.Internal.Conc.Sync`.
On the road to address #25365.
-
8c389e8c
by Ben Gamari at 2026-01-09T20:22:16-05:00
base: Capture backtrace from throwSTM
Implements core-libraries-committee#297.
Fixes #25365.
-
e1ce1fc3
by Ben Gamari at 2026-01-09T20:22:16-05:00
base: Annotate rethrown exceptions in catchSTM with WhileHandling
Implements core-libraries-committee#298
-
c4ebdbdf
by Cheng Shao at 2026-01-09T20:23:06-05:00
compiler: make getPrim eagerly evaluate its result
This commit makes `GHC.Utils.Binary.getPrim` eagerly evaluate its
result, to avoid accidental laziness when future patches build other
binary parsers using `getPrim`.
-
66a0c4f7
by Cheng Shao at 2026-01-09T20:23:06-05:00
compiler: implement fast get/put for Word16/Word32/Word64
Previously, `GHC.Utils.Binary` contains `get`/`put` functions for
`Word16`/`Word32`/`Word64` which always loads and stores them as
big-endian words at a potentially unaligned address. The previous
implementation is based on loads/stores of individual bytes and
concatenating bytes with bitwise operations, which currently cannot be
fused to a single load/store operation by GHC.
This patch implements fast `get`/`put` functions for
`Word16`/`Word32`/`Word64` based on a single memory load/store, with
an additional `byteSwap` operation on little-endian hosts. It is based
on unaligned load/store primops added since GHC 9.10, and we already
require booting with at least 9.10, so it's about time to switch to
this faster path.
-
641ec3f0
by Simon Peyton Jones at 2026-01-09T20:23:55-05:00
Fix scoping errors in specialisation
Using -fspecialise-aggressively in #26682 showed up a couple of
subtle errors in the type-class specialiser.
* dumpBindUDs failed to call `deleteCallsMentioning`, resulting in a
call that mentioned a dictionary that was not in scope. This call
has been missing since 2009!
commit c43c981705ec33da92a9ce91eb90f2ecf00be9fe
Author: Simon Peyton Jones <simonpj@microsoft.com>
Date: Fri Oct 23 16:15:51 2009 +0000
Fixed by re-combining `dumpBindUDs` and `dumpUDs`.
* I think there was another bug involving the quantified type
variables in polymorphic specialisation. In any case I refactored
`specHeader` and `spec_call` so that the former looks for the
extra quantified type variables rather than the latter. This
is quite a worthwhile simplification: less code, easier to grok.
Test case in simplCore/should_compile/T26682,
brilliantly minimised by @sheaf.
-
2433e91d
by Cheng Shao at 2026-01-09T20:24:43-05:00
compiler: change sectionProtection to take SectionType argument
This commit changes `sectionProtection` to only take `SectionType`
argument instead of whole `Section`, since it doesn't need the Cmm
section content anyway, and it can then be called in parts of NCG
where we only have a `SectionType` in scope.
-
e5926fbe
by Cheng Shao at 2026-01-09T20:24:43-05:00
compiler: change isInitOrFiniSection to take SectionType argument
This commit changes `isInitOrFiniSection` to only take `SectionType`
argument instead of whole `Section`, since it doesn't need the Cmm
section content anyway, and it can then be called in parts of NCG
where we only have a `SectionType` in scope. Also marks it as
exported.
-
244d57d7
by Cheng Shao at 2026-01-09T20:24:43-05:00
compiler: fix split sections on windows
This patch fixes split sections on windows by emitting the right
COMDAT section header in NCG, see added comment for more explanation.
Fix #26696 #26494.
-------------------------
Metric Decrease:
LargeRecord
T9675
size_hello_artifact
size_hello_artifact_gzip
size_hello_unicode
size_hello_unicode_gzip
Metric Increase:
T13035
-------------------------
Co-authored-by: Codex <codex@openai.com>
-
182f3d0f
by Cheng Shao at 2026-01-09T20:25:28-05:00
iserv: add comment about -fkeep-cafs
-
49675b69
by Matthew Craven at 2026-01-09T20:26:14-05:00
Account for "stupid theta" in demand sig for DataCon wrappers
Fixes #26748.
-
f3c18890
by Samuel Thibault at 2026-01-10T15:48:22+01:00
hurd: Fix getExecutablePath build
3939a8bf93e27 ("GNU/Hurd: Add getExecutablePath support") added using
/proc/self/exe for GNU/Hurd but missed adding the required imports for
the corresponding code.
-
7f15bd15
by Samuel Thibault at 2026-01-12T07:16:25-05:00
Fix the OS string encoding for GNU/Hurd
Following https://github.com/haskell/cabal/pull/9434/files , and as seen
in the various gnu_HOST_OS usages in the source code, it is expected that
GNU/Hurd is advertised as "gnu", like the autotools do.
-
1db2f240
by Andrew Lelechenko at 2026-01-12T07:17:06-05:00
Add since annotation for Data.Bifoldable1
Fixes #26432
-
e038a383
by Sven Tennie at 2026-01-12T07:17:49-05:00
Ignore Windows CI tool directories in Git
Otherwise, we see thousands of changes in `git status` which is very
confusing to work with.
-
023c301c
by sheaf at 2026-01-13T04:57:30-05:00
Don't re-use stack slots for growing registers
This commit avoids re-using a stack slot for a register that has grown
but already had a stack slot.
For example, suppose we have stack slot assigments
%v1 :: FF64 |-> StackSlot 0
%v2 :: FF64 |-> StackSlot 1
Later, we start using %v1 at a larger format (e.g. F64x2) and we need
to spill it again. Then we **must not** use StackSlot 0, as a spill
at format F64x2 would clobber the data in StackSlot 1.
This can cause some fragmentation of the `StackMap`, but that's probably
OK.
Fixes #26668
-
d0966e64
by fendor at 2026-01-13T04:58:11-05:00
Remove `traceId` from ghc-pkg executable
-
20d7efec
by Simon Peyton Jones at 2026-01-13T12:41:22-05:00
Make SpecContr rules fire a bit later
See #26615 and Note [SpecConstr rule activation]
-
8bc4eb8c
by Andrew Lelechenko at 2026-01-13T12:42:03-05:00
Upgrade mtl submodule to 2.3.2
Fixes #26656
-
c94aaacd
by Cheng Shao at 2026-01-13T12:42:44-05:00
compiler: remove iserv and only use on-demand external interpreter
This patch removes `iserv` from the tree completely. Hadrian would no
longer build or distribute `iserv`, and the GHC driver would use the
on-demand external interpreter by default when invoked with
`-fexternal-interpreter`, without needing to specify `-pgmi ""`. This
has multiple benefits:
- It allows cleanup of a lot of legacy hacks in the hadrian codebase.
- It paves the way for running cross ghc's iserv via cross emulator
(#25523), fixing TH/ghci support for cross targets other than
wasm/js.
-
c1fe0097
by Peter Trommler at 2026-01-14T03:54:49-05:00
PPC NCG: Fix shift right MO code
The shift amount in shift right [arithmetic] MOs is machine word
width. Therefore remove unnecessary zero- or sign-extending of
shift amount.
It looks harmless to extend the shift amount argument because the
shift right instruction uses only the seven lowest bits (i. e. mod 128).
But now we have a conversion operation from a smaller type to word width
around a memory load at word width. The types are not matching up but
there is no check done in CodeGen. The necessary conversion from word
width down to the smaller width would be translated into a no-op on
PowerPC anyway. So all seems harmless if it was not for a small
optimisation in getRegister'.
In getRegister' a load instruction with the smaller width of the
conversion operation was generated. This loaded the most significant
bits of the word in memory on a big-endian platform. These bits were
zero and hence shift right was used with shift amount zero and not one
as required in test Sized.
Fixes #26519
-
2dafc65a
by Cheng Shao at 2026-01-14T03:55:31-05:00
Tree-wide cleanup of cygwin logic
GHC has not supported cygwin for quite a few years already, and will
not resume support in the forseeable future. The only supported
windows toolchain is clang64/clangarm64 of the msys2 project. This
patch cleans up the unused cygwin logic in the tree.
Co-authored-by: Codex <codex@openai.com>
-
66b96e2a
by Teo Camarasu at 2026-01-14T03:56:13-05:00
Set default eventlog-flush-interval to 5s
Resolves #26707
-
d0254579
by Andrew Lelechenko at 2026-01-14T03:56:53-05:00
Document when -maxN RTS option was added
-
f25e2b12
by Cheng Shao at 2026-01-14T11:10:39-05:00
testsuite: remove obsolete --ci option from the testsuite driver
This patch removes the obsolete `--ci` option from the testsuite
driver: neither the CI scripts nor hadrian ever invokes the testsuite
driver with `--ci`, and the perf notes are always fetched to the
`refs/notes/perf` local reference anyway.
-
7964763b
by Julian Ospald at 2026-01-14T11:11:31-05:00
Fix fetch_cabal
* download cabal if the existing one is of an older version
* fix FreeBSD download url
* fix unpacking on FreeBSD
-
6b0129c1
by Julian Ospald at 2026-01-14T11:11:31-05:00
Bump toolchain in CI
-
0f53ccc6
by Julian Ospald at 2026-01-14T11:11:31-05:00
Use libffi-clib
Previously, we would build libffi via hadrian
and bundle it manually with the GHC bindist.
This now moves all that logic out of hadrian
and allows us to have a clean Haskell package
to build and link against and ship it without
extra logic.
This patch still retains the ability to link
against a system libffi.
The main reason of bundling libffi was that on
some platforms (e.g. FreeBSD and Mac), system libffi
is not visible to the C toolchain by default,
so users would require settings in e.g. cabal
to be able to compile anything.
This adds the submodule libffi-clib to the repository.
-
5e1cd595
by Peng Fan at 2026-01-14T11:12:26-05:00
NCG/LA64: add support for la664 micro architecture
Add '-mla664' flag to LA664, which has some new features:
atomic instructions, dbar hints, etc.
'LA464' is the default so that unrecognized instructions are not
generated.
-
c56567ec
by Simon Peyton Jones at 2026-01-15T23:19:04+00:00
Add evals for strict data-con args in worker-functions
This fixes #26722, by adding an eval in a worker for
arguments of strict data constructors, even if the
function body uses them strictly.
See (WIS1) in Note [Which Ids should be strictified]
I took the opportunity to make substantial improvements in the
documentation for call-by-value functions. See especially
Note [CBV Function Ids: overview] in GHC.Types.Id.Info
Note [Which Ids should be CBV candidates?] ditto
Note [EPT enforcement] in GHC.Stg.EnforceEpt
among others.
-
9719ce5d
by Simon Peyton Jones at 2026-01-15T23:19:04+00:00
Improve `interestingArg`
This function analyses a function's argument to see if it is
interesting enough to deserve an inlining discount. Improvements
for
* LitRubbish arguments
* exprIsExpandable arguments
See Note [Interesting arguments] which is substantially rewritten.
-
7b616b9f
by Cheng Shao at 2026-01-16T06:45:00-05:00
compiler: fix regression when compiling foreign stubs in the rts unit
This patch fixes a regression when compiling foreign stubs in the rts
unit introduced in 05e25647f72bc102061af3f20478aa72bff6ff6e. A simple
revert would fix it, but it's better to implement a proper fix with
comment for better understanding of the underlying problem, see the
added comment for explanation.
Co-authored-by: Codex <codex@openai.com>
-
c343ef64
by Sylvain Henry at 2026-01-16T06:45:51-05:00
base: remove GHC.JS.Prim.Internal.Build (#23432)
See accepted CLC proposal https://github.com/haskell/core-libraries-committee/issues/329
-
29c0aceb
by Simon Peyton Jones at 2026-01-16T17:18:11-05:00
Improve newtype unwrapping
Ticket #26746 describes several relatively-minor shortcomings of newtype
unwrapping. This MR addresses them, while also (arguably) simplifying
the code a bit.
See new Note [Solving newtype equalities: overview]
and Note [Decomposing newtype equalities]
and Note [Eager newtype decomposition]
and Note [Even more eager newtype decomposition]
For some reason, on Windows only, runtime allocations decrease for test
T5205 (from 52k to 48k). I have not idea why. No change at all on Linux.
I'm just going to accept the change. (I saw this same effect in another
MR so I think it's a fault in the baseline.)
Metric Decrease:
T5205
-
8b59e62c
by Andreas Klebinger at 2026-01-16T17:18:52-05:00
testsuite: Widen acceptance window for T5205.
Fixes #26782
-
9e5e0234
by mangoiv at 2026-01-17T06:03:03-05:00
add a new issue template for getting verified
To reduce spam created by new users, we will in future not grant
any rights but reporting issues to new users. That is why we will
have to be able to verify them. The added issue template serves that
purpose.
-
b18b2c42
by Cheng Shao at 2026-01-17T06:03:44-05:00
llvm: fix split sections for llvm backend
This patch fixes split sections for llvm backend:
- Pass missing `--data-sections`/`--function-sections` flags to
llc/opt.
- Use `@llvm.compiler.used` instead of `@llvm.used` to avoid sections
being unnecessarily retained at link-time.
Fixes #26770.
-------------------------
Metric Decrease:
libdir
size_hello_artifact
size_hello_unicode
-------------------------
Co-authored-by: Codex <codex@openai.com>
-
ebf66f67
by Cheng Shao at 2026-01-17T13:16:50-05:00
Update autoconf scripts
Scripts taken from autoconf a2287c3041a3f2a204eb942e09c015eab00dc7dd
-
598624b9
by Andreas Klebinger at 2026-01-17T13:17:32-05:00
CString.hs: Update incorrect comment.
Fixes #26322
-
eea2036b
by Cheng Shao at 2026-01-18T10:00:49-05:00
libraries: bump haskeline submodule to 0.8.4.1
This patch bumps the haskeline submodule to 0.8.4.1 which includes an
important fix for an ANSI handling bug on Windows
(https://github.com/haskell/haskeline/pull/126).
-
87d8f6c2
by Cheng Shao at 2026-01-18T10:01:30-05:00
hadrian: replace default -H32m/-H64m with -O64M to improve mutator productivity
Most hadrian build flavours pass `-H32m`/`-H64m` to GHC as
conventional wisdom to improve mutator productivity and reduce GC
overhead. They were inherited from the legacy Make build system, and
there used to be make flags to instrument a build process with
`-Rghc-timing` option to collect GC stats of each GHC run from stderr.
It's time to revisit whether there are better defaults for
`-H32m`/`-H64m`, and this patch changes it to `-O64M` which indeed
improves mutator productivity based on real statistics. `-O64M` is
more aggressive than `-H64m`; it allows the old generation to grow to
at least 64M before triggering major GC and reduces major GC runs.
The stats of a clean build with `validate` flavour and `-H64m`:
```
h64m.log
matched RTS stat lines: 5499
sum MUT cpu : 2400.808 s
sum GC cpu : 1378.292 s
sum MUT elapsed : 2788.253 s
sum GC elapsed : 1389.233 s
GC/MUT cpu ratio : 0.574 (GC is 57.4% of MUT)
GC/MUT elapsed ratio : 0.498 (GC is 49.8% of MUT)
GC fraction of (MUT+GC) cpu : 36.5%
GC fraction of (MUT+GC) elapsed : 33.3%
per-line GC/MUT cpu ratio: median 0.691, p90 1.777
per-line GC/MUT elapsed ratio: median 0.519, p90 1.081
```
The stats of a clean build with `validate` flavour and `-O64M`:
```
o64m.log
matched RTS stat lines: 5499
sum MUT cpu : 2377.383 s
sum GC cpu : 1127.146 s
sum MUT elapsed : 2758.857 s
sum GC elapsed : 1135.587 s
GC/MUT cpu ratio : 0.474 (GC is 47.4% of MUT)
GC/MUT elapsed ratio : 0.412 (GC is 41.2% of MUT)
GC fraction of (MUT+GC) cpu : 32.2%
GC fraction of (MUT+GC) elapsed : 29.2%
per-line GC/MUT cpu ratio: median 0.489, p90 1.099
per-line GC/MUT elapsed ratio: median 0.367, p90 0.806
```
Mutator time is roughly in the same ballpark, but GC CPU time has
reduced by 18.22%, and mutator productivity has increased from 63.5%
to 67.8%.
-
8372e13d
by Cheng Shao at 2026-01-18T10:02:12-05:00
rts: remove unused .def files from rts/win32
This patch removes unused .def files from `rts/win32`, given we don't
build .dll files for rts/ghc-internal/ghc-prim at all. Even when we
resurrect win32 dll support at some point in the future, these .def
files still contain incorrect symbols anyway and won't be of any use.
-
f6af485d
by Cheng Shao at 2026-01-18T10:03:19-05:00
.gitmodules: use gitlab mirror for the libffi-clib submodule
This patch fixes .gitmodules to use the gitlab mirror for the
libffi-clib submodule, to make it coherent with other submodules that
allow ghc developers to experiment with wip branches in submodules for
ghc patches. Fixes #26783.
-
41432d25
by Cheng Shao at 2026-01-18T10:05:13-05:00
hadrian: remove the horrible i386 speedHack
When hadrian builds certain rts objects for i386, there's a horrible
speedHack that forces -fno-PIC even for dynamic ways of those objects.
This is not compatible with newer versions of gcc/binutils as well as
clang/lld, and this patch removes it. Fixes #26792.
-
323eb8f0
by Cheng Shao at 2026-01-18T21:48:19-05:00
hadrian: enable split sections for cross stage0
This patch fixes a minor issue with `splitSectionsArgs` in hadrian:
previously, it's unconditionally disabled for stage0 libraries because
it's not going to be shipped in the final bindists. But it's only true
when not cross compiling. So for now we also need to enable it for
cross stage0 as well.
-
3fadfefe
by Andreas Klebinger at 2026-01-18T21:49:01-05:00
RTS: Document -K behaviour better
-
30f442a9
by Teo Camarasu at 2026-01-20T13:57:26-05:00
base: don't expose GHC.Num.{BigNat, Integer, Natural}
We no longer expose GHC.Num.{BigNat, Integer, Natural} from base instead users should get these modules from ghc-bignum.
We make this change to insulate end users from changes to GHC's implementation of big numbers.
Implements CLC proposal 359: https://github.com/haskell/core-libraries-committee/issues/359
-
75a9053d
by Teo Camarasu at 2026-01-20T13:58:07-05:00
base: deprecate GHC internals in GHC.Num
Implements CLC proposal: https://github.com/haskell/core-libraries-committee/issues/360
-
9534b032
by Andreas Klebinger at 2026-01-20T13:58:50-05:00
ghc-experimental: Update Changelog
I tried to reconstruct a high level overview of the changes and when
they were made since we introduced it.
Fixes #26506
Co-authored-by: Teo Camarasu <teofilcamarasu@gmail.com>
-
346f2f5a
by Cheng Shao at 2026-01-20T13:59:30-05:00
hadrian: remove RTS options in ghc-in-ghci flavour
This patch removes the RTS options passed to ghc in ghc-in-ghci
flavour, to workaround command line argument handling issue in
hls/hie-boot that results in `-O64M` instead of `+RTS -O64M -RTS`
being passed to ghc. It's not a hadrian bug per se, since ghc's own
ghc-in-ghci multi repl works fine, but we should still make sure HLS
works. Closes #26801.
-
759fd15a
by Andreas Klebinger at 2026-01-21T16:05:28-05:00
Don't build GHC with -Wcompat
Without bumping the boot compiler the warnings it produces are often not
actionable leading to pointless noise.
Fixes #26800
-
3172db94
by Torsten Schmits at 2026-01-21T16:06:11-05:00
Use the correct field of ModOrigin when formatting error message listing hidden reexports
-
485c12b2
by Cheng Shao at 2026-01-21T16:06:54-05:00
Revert "hadrian: handle findExecutable "" gracefully"
This reverts commit 1e5752f64a522c4025365856d92f78073a7b3bba. The
underlying issue has been fixed in
https://github.com/haskell/directory/commit/75828696e7145adc09179111a0d631b9a09963a4
and present since 1.3.9.0, and hadrian directory lower bound is
1.3.9.0, so we can revert our own in house hack now.
-
5efb58dc
by Cheng Shao at 2026-01-21T16:07:36-05:00
rts: fix typo in TICK_ALLOC_RTS
This patch fixes a typo in the `TICK_ALLOC_RTS` macro, the original
`bytes` argument was silently dropped. The Cmm code has its own
version of `TICK_ALLOC_RTS` not affected by this typo, it affected the
C RTS, and went unnoticed because the variable `n` happened to also be
available at its call site. But the number was incorrect. Also fixes
its call site since `WDS()` is not available in C.
-
c406ea69
by Cheng Shao at 2026-01-21T16:07:36-05:00
rts: remove broken & unused ALLOC_P_TICKY
This patch removes the `ALLOC_P_TICKY` macro from the rts, it's
unused, and its expanded code is already broken.
-
34a27e20
by Simon Peyton Jones at 2026-01-21T16:08:17-05:00
Make the implicit-parameter class have representational role
This MR addresses #26737, by making the built-in class IP
have a representational role for its second parameter.
See Note [IP: implicit parameter class] in
ghc-internal:GHC.Internal.Classes.IP
In fact, IP is (unfortunately, currently) exposed by
base:GHC.Base, so we ran a quick CLC proposal to
agree the change:
https://github.com/haskell/core-libraries-committee/issues/385
Some (small) compilations get faster because they only need to
load (small) interface file GHC.Internal.Classes.IP.hi,
rather than (large) GHC.Internal.Classes.hi.
Metric Decrease:
T10421
T12150
T12425
T24582
T5837
T5030
-
ca79475f
by Cheng Shao at 2026-01-21T16:09:00-05:00
testsuite: avoid re.sub in favor of simple string replacements
This patch refactors the testsuite driver and avoids the usage of
re.sub in favor of simple string replacements when possible. The
changes are not comprehensive, and there are still a lot of re.sub
usages lingering around the tree, but this already addresses a major
performance bottleneck in the testsuite driver that might has to do
with quadratic or worse slowdown in cpython's regular expression
engine when handling certain regex patterns with large strings.
Especially on i386, and i386 jobs are the bottlenecks of all full-ci
validate pipelines!
Here are the elapsed times of testing x86_64/i386 with -j48 before
this patch:
x86_64: `Build completed in 6m06s`
i386: `Build completed in 1h36m`
And with this patch:
x86_64: `Build completed in 4m55s`
i386: `Build completed in 4m23s`
Fixes #26786.
Co-authored-by: Codex <codex@openai.com>
-
88c93796
by Zubin Duggal at 2026-01-21T16:09:42-05:00
ghc-toolchain: Also configure windres on non-windows platforms.
It may be needed for cross compilation.
Fixes #24588
-
9788c0ec
by Cheng Shao at 2026-01-21T16:10:24-05:00
ghci: print external interpreter trace messages to stderr instead of stdout
This patch makes ghci print external interpreter trace messages to
stderr instead of stdout, which is a much saner choice for diagnostic
information. Closes #26807.
-
0491f08a
by Sylvain Henry at 2026-01-22T03:44:26-05:00
GC: don't use CAS without PARALLEL_GC on
If we're not using the parallel GC, there is no reason to do a costly
CAS. This was flagged as taking time in a perf profile.
-
211a8f56
by Sylvain Henry at 2026-01-22T03:44:26-05:00
GC: suffix parallel GC with "par" instead of "thr"
Avoid some potential confusion (see discussion in !15351).
-
77a23cbd
by fendor at 2026-01-22T03:45:08-05:00
Remove blanket ignore that covers libraries/
-
18bf7f5c
by Léana Jiang at 2026-01-22T08:58:45-05:00
doc: update Flavour type in hadrian user-settings
-
3d5a1365
by Cheng Shao at 2026-01-22T08:59:28-05:00
hadrian: add missing notCross predicate for stage0 -O0
There are a few hard-coded hadrian args that pass -O0 when compiling
some heavy modules in stage0, which only makes sense when not
cross-compiling and when cross-compiling we need properly optimized
stage0 packages. So this patch adds the missing `notCross` predicate
in those places.
-
ee937134
by Matthew Pickering at 2026-01-22T09:00:10-05:00
Fix ghc-experimental GHC.Exception.Backtrace.Experimental module
This module wasn't added to the cabal file so it was never compiled or
included in the library.
-
1b490f5a
by Zubin Duggal at 2026-01-22T09:00:53-05:00
hadrian: Add ghc-{experimental,internal}.cabal to the list of dependencies of the doc target
We need these files to detect the version of these libraries
Fixes #26738
-
cdb74049
by Cheng Shao at 2026-01-22T14:52:36-05:00
rts: avoid Cmm loop to initialize Array#/SmallArray#
Previously, `newArray#`/`newSmallArray#` called an RTS C function to
allocate the `Array#`/`SmallArray#`, then used a Cmm loop to
initialize the elements. Cmm doesn't have native for-loop so the code
is a bit awkward, and it's less efficient than a C loop, since the C
compiler can effectively vectorize the loop with optimizations.
So this patch moves the loop that initializes the elements to the C
side. `allocateMutArrPtrs`/`allocateSmallMutArrPtrs` now takes a new
`init` argument and initializes the elements if `init` is non-NULL.
-
4c784f00
by Cheng Shao at 2026-01-22T14:53:19-05:00
Fix testsuite run for +ipe flavour transformer
This patch makes the +ipe flavour transformer pass the entire
testsuite:
- An RTS debug option `-DI` is added, the IPE trace information is now
only printed with `-DI`. The test cases that do require IPE trace
are now run with `-DI`.
- The testsuite config option `ghc_with_ipe` is added, enabled when
running the testsuite with `+ipe`, which skips a few tests that are
sensitive to eventlog output, allocation patterns etc that can fail
under `+ipe`.
This is the first step towards #26799.
Co-authored-by: Codex <codex@openai.com>
-
be8e5236
by Ben Gamari at 2026-01-23T03:28:45-05:00
hadrian: Bump QuickCheck upper bound
This patch bumps QuickCheck upper bound to 2.18. selftest rule
manually tested to work with current latest QuickCheck-2.17.1.0.
-
5aa328fb
by Zubin Duggal at 2026-01-23T03:29:30-05:00
Add genindex to index.rst. This adds a link to the index in the navigation bar.
Fixes #26437
-
917ab8ff
by Oleg Grenrus at 2026-01-23T10:52:55-05:00
Export labelThread from Control.Concurrent
-
3f5e8d80
by Cheng Shao at 2026-01-23T10:53:37-05:00
ci: only push perf notes on master/release branches
This patch fixes push_perf_notes logic in ci.sh to only push perf
notes on master/release branches. We used to unconditionally push perf
notes even in MRs, but the perf numbers in the wip branches wouldn't
be used as baseline anyway, plus this is causing a space leak in the
ghc-performance-notes repo. See #25317 for the perf notes repo size
problem.
Co-authored-by: Codex <codex@openai.com>
-
414b9593
by Cheng Shao at 2026-01-24T07:11:51-05:00
ci: remove duplicate keys in .gitlab-ci.yml
This patch removes accidentally duplicate keys in `.gitlab-ci.yml`.
The YAML spec doesn't allow duplicate keys in the first place, and
according to GitLab docs
(https://docs.gitlab.com/ci/yaml/yaml_optimization/#anchors), the
latest key overrides the earlier entries.
-
e5cb5491
by Cheng Shao at 2026-01-24T07:12:34-05:00
hadrian: drop obsolete configure/make builder logic for libffi
This patch drops obsolete hadrian logic around `Configure
libffiPath`/`Make libffiPath` builders, they are no longer needed
after libffi-clib has landed. Closes #26815.
-
2d160222
by Simon Hengel at 2026-01-24T07:13:17-05:00
Fix typo in roles.rst
-
56db94f7
by Peter Trommler at 2026-01-26T11:26:18+01:00
PPC NCG: Generate clear right insn at arch width
The clear right immediate (clrrxi) is only available in word and
doubleword width. Generate clrrxi instructions at architecture
width for all MachOp widths.
Fixes #24145
-
5957a8ad
by Wolfgang Jeltsch at 2026-01-27T06:11:40-05:00
Add operations for obtaining operating-system handles
This contribution implements CLC proposal #369. It adds operations for
obtaining POSIX file descriptors and Windows handles that underlie
Haskell handles. Those operating system handles can also be obtained
without such additional operations, but this is more involved and, more
importantly, requires using internals.
-
86a0510c
by Greg Steuck at 2026-01-27T06:12:34-05:00
Move flags to precede patterns for grep and read files directly
This makes the tests pass with non-GNU (i.e. POSIX-complicant) tools.
There's no reason to use cat and pipe where direct file argument works.
-
50761451
by Cheng Shao at 2026-01-27T21:51:23-05:00
ci: update darwin boot ghc to 9.10.3
This patch updates darwin boot ghc to 9.10.3, along with other related
updates, and pays off some technical debt here:
- Update `nixpkgs` and use the `nixpkgs-25.05-darwin` channel.
- Update the `niv` template.
- Update LLVM to 21 and update `llvm-targets` to reflect LLVM 21
layout changes for arm64/x86_64 darwin targets.
- Use `stdenvNoCC` to prevent nix packaged apple sdk from being used
by boot ghc, and manually set `DEVELOPER_DIR`/`SDKROOT` to enforce
the usage of system-wide command line sdk for macos.
- When building nix derivation for boot ghc, run `configure` via the
`arch` command so that `configure` and its subprocesses pick up the
manually specified architecture.
- Remove the previous horrible hack that obliterates `configure` to
make autoconf test result in true. `configure` now properly does its
job.
- Remove the now obsolete configure args and post install settings
file patching logic.
- Use `scheme-small` for texlive to avoid build failures in certain
unused texlive packages, especially on x86_64-darwin.
-
94dcd15e
by Matthew Pickering at 2026-01-27T21:52:05-05:00
Evaluate backtraces for "error" exceptions at the moment they are thrown
See Note [Capturing the backtrace in throw] and
Note [Hiding precise exception signature in throw] which explain the
implementation.
This commit makes `error` and `throw` behave the same with regard to
backtraces. Previously, exceptions raised by `error` would not contain
useful IPE backtraces.
I did try and implement `error` in terms of `throw` but it started to
involve putting diverging functions into hs-boot files, which seemed to
risky if the compiler wouldn't be able to see if applying a function
would diverge.
CLC proposal: https://github.com/haskell/core-libraries-committee/issues/383
Fixes #26751
-
ef35e3ea
by Teo Camarasu at 2026-01-27T21:52:46-05:00
ghc-internal: move all Data instances to Data.Data
Most instances of Data are defined in GHC.Internal.Data.Data.
Let's move all remaining instance there.
This moves other modules down in the dependency hierarchy allowing for
more parallelism, and it decreases the likelihood that we would need to
load this heavy .hi file if we don't actually need it.
Resolves #26830
Metric Decrease:
T12227
T16875
-
5e0ec555
by sheaf at 2026-01-28T06:56:38-05:00
Add test case for #25679
This commit adds the T25679 test case. The test now passes, thanks to
commit 1e53277af36d3f0b6ad5491f70ffc5593a49dcfd.
Fixes #25679
-
f1cd1611
by sheaf at 2026-01-28T06:56:38-05:00
Improve defaulting of representational equalities
This commit makes the defaulting of representational equalities, introduced
in 1e53277a, a little bit more robust. Now, instead of calling the eager
unifier, it calls the full-blown constraint solver, which means that it can
handle some subtle situations, e.g. involving functional dependencies and
type-family injectivity annotations, such as:
type family F a = r | r -> a
type instance F Int = Bool
[W] F beta ~R Bool
-
25edf516
by sheaf at 2026-01-28T06:56:38-05:00
Improve errors for unsolved representational equalities
This commit adds a new field of CtLoc, CtExplanations, which allows the
typechecker to leave some information about what it has done. For the moment,
it is only used to improve error messages for unsolved representational
equalities. The typechecker will now accumulate, when unifying at
representational role:
- out-of-scope newtype constructors,
- type constructors that have nominal role in a certain argument,
- over-saturated type constructors,
- AppTys, e.g. `c a ~R# c b`, to report that we must assume that 'c' has
nominal role in its parameters,
- data family applications that do not reduce, potentially preventing
newtype unwrapping.
Now, instead of having to re-construct the possible errors after the fact,
we simply consult the CtExplanations field.
Additionally, this commit modifies the typechecker error messages that
concern out-of-scope newtype constructors. The error message now depends
on whether we have an import suggestion to provide to the user:
- If we have an import suggestion for the newtype constructor,
the message will be of the form:
The data constructor MkN of the newtype N is out of scope
Suggested fix: add 'MkN' to the import list in the import of 'M'
- If we don't have any import suggestions, the message will be
of the form:
NB: The type 'N' is an opaque newtype, whose constructor is hidden
Fixes #15850, #20289, #20468, #23731, #25949, #26137
-
4d0e6da1
by Simon Peyton Jones at 2026-01-28T06:57:19-05:00
Fix two bugs in short-cut constraint solving
There are two main changes here:
* Use `isSolvedWC` rather than `isEmptyWC` in `tryShortCutSolver`
The residual constraint may have some fully-solved, but
still-there implications, and we don't want them to abort short
cut solving! That bug caused #26805.
* In the short-cut solver, we abandon the fully-solved residual
constraint; but we may thereby lose track of Givens that are
needed, and either report them as redundant or prune evidence
bindings that are in fact needed.
This bug stopped the `constraints` package from compiling;
see the trail in !15389.
The second bug led me to (another) significant refactoring
of the mechanism for tracking needed EvIds. See the new
Note [Tracking needed EvIds] in GHC.Tc.Solver.Solve
It's simpler and much less head-scratchy now.
Some particulars:
* An EvBindsVar now tracks NeededEvIds
* We deal with NeededEvIds for an implication only when it is
fully solved. Much simpler!
* `tryShortCutTcS` now takes a `TcM WantedConstraints` rather than
`TcM Bool`, so that is can plumb the needed EvIds correctly.
* Remove `ic_need` and `ic_need_implic` from Implication (hooray),
and add `ics_dm` and `ics_non_dm` to `IC_Solved`.
Pure refactor
* Shorten data constructor `CoercionHole` to `CH`, following
general practice in GHC.
* Rename `EvBindMap` to `EvBindsMap` for consistency
-
662480b7
by Cheng Shao at 2026-01-28T06:58:00-05:00
ci: use debian validate bindists instead of fedora release bindists in testing stage
This patch changes the `abi-test`, `hadrian-multi` and `perf` jobs in
the full-ci pipeline testing stage to use debian validate bindists
instead of fedora release bindists, to increase pipeline level
parallelism and allow full-ci pipelines to complete earlier. Closes #26818.
-
39581ec6
by Cheng Shao at 2026-01-28T06:58:40-05:00
ci: run perf test with -j$cores
This patch makes the perf ci job compile Cabal with -j$cores to speed
up the job.
-
607b287b
by Wolfgang Jeltsch at 2026-01-28T15:41:53+02:00
Remove `GHC.Desugar` from `base`
`GHC.Desugar` was deprecated and should have been removed in GHC 9.14.
However, the removal was forgotten, although there was a code block that
was intended to trigger a compilation error when the GHC version in use
was 9.14 or later. This code sadly didn’t work, because the
`__GLASGOW_HASKELL__` macro was misspelled as `__GLASGOW_HASKELL`.
-
e8f5a45d
by sterni at 2026-01-29T04:19:18-05:00
users_guide: fix runtime error during build with Sphinx 9.1.0
Appears that pathto is stricter about what it accepts now.
Tested Sphinx 8.2.3 and 9.1.0 on the ghc-9.10 branch.
Resolves #26810.
Co-authored-by: Martin Weinelt <hexa@darmstadt.ccc.de>
-
ce2d62fb
by Jessica Clarke at 2026-01-29T19:48:51-05:00
PPC NCG: Use libcall for 64-bit cmpxchg on 32-bit PowerPC
There is no native instruction for this, and even if there were a
register pair version we could use, the implementation here is assuming
the values fit in a single register, and we end up only using / defining
the low halves of the registers.
Fixes: b4d39adbb5 ("PrimOps: Add CAS op for all int sizes")
Fixes: #23969
-
43d97761
by Michael Karcher at 2026-01-29T19:49:43-05:00
NCG for PPC: add pattern for CmmRegOff to iselExpr64
Closes #26828
-
aeeb4a20
by Matthew Pickering at 2026-01-30T11:42:47-05:00
determinism: Use deterministic map for Strings in TyLitMap
When generating typeable evidence the types we need evidence for all
cached in a TypeMap, the order terms are retrieved from a type map
determines the order the bindings appear in the program.
A TypeMap is quite diligent to use deterministic maps, apart from in the
TyLitMap, which uses a UniqFM for storing strings, whose ordering
depends on the Unique of the FastString.
This can cause non-deterministic .hi and .o files.
An unexpected side-effect is the error message but RecordDotSyntaxFail8
changing. I looked into this with Sam and this change caused the
constraints to be solved in a different order which results in a
slightly different error message. I have accepted the new test, since
the output before was non-deterministic and the new output is consistent
with the other messages in that file.
Fixes #26846
-
9e4d70c2
by Andrew Lelechenko at 2026-01-30T11:43:29-05:00
Upgrade text submodule to 2.1.4
-
631fa5ae
by Recursion Ninja at 2026-01-31T22:30:11+00:00
Decouple `L.S.H.Decls` from importing `GHC.Types.Basic`
Data-types within `GHC.Types.Basic` which describe components of
the AST are migrated to `Language.Haskell.Syntax.Basic`. Related
function definitions are also moved.
Types moved to L.H.S. because they are part of the AST:
* TopLevelFlag
* RuleName
Types moved from L.H.S. to GHC.Hs. because they are not needed in the AST:
* TyConFlavour
* TypeOrData
* NewOrData
Migrated instances:
* `Outputable` instances moved to in `GHC.Utils.Outputable`
* `Binary` instance of `Boxity` moved to to `GHC.Utils.Binary`
* Other `Binary` instances are orphans to be migrated later.
The `OverlapMode` data-type is given a TTG extension point.
The `OverlapFlag` data-type, which depends on `OverlapMode`,
is updated to support `OverlapMode` with a GHC "pass" type paramerter.
In order to avoid module import cycles, `OverlapMode` and `OverlapFlag`
are migrated to new modules (no way around this).
* Migrated `OverlapMode` to new module `Language.Haskell.Syntax.Overlap`
* Migrated `OverlapFlag` to new module `GHC.Hs.Decls.Overlap`
-
9769cc03
by Simon Hengel at 2026-02-01T04:21:03-05:00
Update the documentation for MultiWayIf (fixes #25376)
(so that it matches the implementation)
-
5fc9442a
by Peter Trommler at 2026-02-01T04:21:44-05:00
hadrian: Fix dependency generation for assembler
Assembler files allow # for comments unless in column 1. A modern
cpp for C treats those a preprocessor directives. We tell gcc that
a .S file is assembler with cpp and not C.
Fixes #26819
-
269c4087
by Simon Peyton Jones at 2026-02-01T19:38:10-05:00
Include current phase in the range for rule/unfoldings
This MR fixes a bad loop in the compiler: #26826.
The fix is to add (WAR2) to
Note [What is active in the RHS of a RULE or unfolding?]
in GHC.Core.Opt.Simplify.Utils
-
ddf1434f
by Vladislav Zavialov at 2026-02-01T19:38:52-05:00
Refactor: merge HsMultilineString into HsString (#26860)
Before this patch, HsLit defined two separate constructors to represent
single-line and multi-line strings:
data HsLit x
...
| HsString (XHsString x) FastString
| HsMultilineString (XHsMultilineString x) FastString
I found this to be an unnecessary complication and an obstacle to unifying
HsLit with HsTyLit. Now we use HsString for both kinds of literals.
One user-facing change here is `ppr (HsString st s)` behaving differently for
single-line strings containing newlines:
x = "first line \
\asdf\n\
\second line"
Previously, the literal was fed to `ftext` with its newlines, producing an
ill-formed SDoc. This issue is now addressed by using `split` for both
single-line and multi-line strings:
vcat $ map text $ split '\n' (unpackFS src)
See the parser/should_fail/T26860ppr test.
In addition (and unrelatedly to the main payload of this patch),
drop the unused pmPprHsLit helper.
-
2b4f463c
by Simon Peyton Jones at 2026-02-02T17:32:32+00:00
Remove exprIsCheap from doFloatFromRhs
See #26854 and Note [Float when expandable]
This patch simplifies the code, by removing an extra unnecessary test.
-
9db7f21f
by Brandon Chinn at 2026-02-03T09:15:10-05:00
Refactor: make function patterns exhaustive
Also added missing (==) logic for:
* HsMultilineString
* HsInt{8,16,32}
* HsWord{8,16,32}
-
aa9c5e2c
by Hécate Kleidukos at 2026-02-03T15:58:35-05:00
driver: Hide source paths at verbosity level 1 by default
-
c64cca1e
by mangoiv at 2026-02-03T15:59:29-05:00
ExplicitLevelImports: check staging for types just like for values
Previously, imported types were entirely exempted from staging checks as
the implicit stage persistance assumed to be all imported types to be
well staged. ExplicitLevelImports' change specification, however, does
not do such an exemption. Thus we want to introduce such a check, just
like we have for values.
ExplicitLevelImports does not, however, talk about local names - from
its perspective, we could theoretically keep treating locally introduced
types specially - e.g. an ill-staged used in a quote would only emit a
warning, not an error. To allow for a potential future migration away
from such wrinkles as the staging check in notFound
(see Note [Out of scope might be a staging error]) we consistently do
the strict staging check that we also do for value if ExplicitLevelImports
is on.
Closes #26098
-
5f0dbeb6
by Simon Hengel at 2026-02-03T16:00:12-05:00
Use Haddock formatting in deprecation message of `initNameCache`
-
01ecb612
by Andreas Klebinger at 2026-02-04T09:56:25-05:00
testsuite: Explicitly use utf-8 encoding in rts-includes linter.
Not doing so caused failures on windows, as python failed to pick a
reasonable encoding even with locale set.
Fixes #26850
-
ea0d1317
by Zubin Duggal at 2026-02-04T09:57:06-05:00
Bump transformers submodule to 0.6.3.0
Fixes #26790
-
cbe4300e
by Simon Peyton Jones at 2026-02-05T04:31:04-05:00
Fix subtle bug in GHC.Core.Utils.mkTick
This patch fixes a decade-old bug in `mkTick`, which
could generate type-incorrect code! See the diagnosis
in #26772.
The new code is simpler and easier to understand.
(As #26772 says, I think it could be improved further.)
-
a193a8da
by Simon Peyton Jones at 2026-02-05T04:31:04-05:00
Modify a debug-trace in the Simplifier
...just to show a bit more information.
-
b579dfdc
by Simon Peyton Jones at 2026-02-05T04:31:04-05:00
Fix long-standing interaction between ticks and casts
The code for Note [Eliminate Identity Cases] was simply wrong when
ticks and casts interacted. This patch fixes the interaction.
It was shown up when validating #26772, although it's not the exactly
the bug that's reported by #26772. Nor is it easy to reproduce, hence
no regression test.
-
fac0de1e
by Cheng Shao at 2026-02-05T04:31:49-05:00
libraries: bump Cabal submodule to 3.16.1.0
-
00589122
by Cheng Shao at 2026-02-05T04:31:49-05:00
libraries: bump deepseq submodule to 1.5.2.0
Also:
- Get rid of usage of deprecated `NFData` function instance in the
compiler
- `T21391` still relies on `NFData` function instance, add
`-Wno-deprecations` for the time being.
-
84474c71
by Cheng Shao at 2026-02-05T04:31:50-05:00
libraries: bump directory submodule to 1.3.10.1
-
1a9f4662
by Cheng Shao at 2026-02-05T04:31:50-05:00
libraries: bump exceptions submodule to 0.10.12
-
2e39a340
by Peng Fan at 2026-02-07T03:42:01-05:00
NCG/LA64: adjust register usage to avoid src-register being clobbered
-
9faf1b35
by Teo Camarasu at 2026-02-07T03:42:43-05:00
ghc-internal: Delete unnecessary GHC.Internal.Data.Ix
This module merely re-exports GHC.Internal.Ix. It was copied from
`base` when `ghc-internal` was split, but there is no reason to have
this now. So, let's delete it.
Resolves #26848
-
d112b440
by Sven Tennie at 2026-02-07T10:47:56-05:00
Add cabal.project file to generate-ci
This fixes the HLS setup for our CI code generation script
(generate-ci).
The project file simply makes `generate-ci` of the cabal file
discoverable.
-
5339f6f0
by Andreas Klebinger at 2026-02-07T10:48:40-05:00
CI: Don't collapse test results.
This puts test output back into the primary test log instead of a
subsection removing the need to expand a section to see test results.
While the intention was good in practice the old behaviour mostly wastes time
by requiring expansion of the section.
Fixes #26882
-
0e1cd2e0
by Evan Piro at 2026-02-08T10:35:16-08:00
Linker.MacOS reduce dynflags import
-
1c79a4cd
by Michael Alan Dorman at 2026-02-09T08:11:51-05:00
Remove `extra_src_files` variable from `testsuite/driver/testlib.py`
While reading through the test harness code, I noticed this variable
with a TODO attached that referenced #12223. Although that bug is
closed, it strongly implied that this special-case variable that only
affected a single test was expected to be removed at some point.
I also looked at 3415bcaa0b1903b5e12dfaadb5b774718e406eab---where it
was added---whose commit message suggested that it would have been
desirable to remove it, but that there were special circumstances that
meant it had to remain (though it doesn't elucidate what those special
circumstances are).
However, the special circumstances were mentioned as if the test was
in a different location than is currently is, so I decided to try
changing the test to use the standard `extra_files` mechanism, which
works in local testing.
This also seems like a reasonable time to remove the script that was
originally used in the transition, since it doesn't really serve a
purpose anymore.
-
0020e38a
by Matthew Pickering at 2026-02-09T17:29:14-05:00
determinism: Use a stable sort in WithHsDocIdentifiers binary instance
`WithHsDocIdentifiers` is defined as
```
71 data WithHsDocIdentifiers a pass = WithHsDocIdentifiers
72 { hsDocString :: !a
73 , hsDocIdentifiers :: ![Located (IdP pass)]
74 }
```
This list of names is populated from `rnHsDocIdentifiers`, which calls
`lookupGRE`, which calls `lookupOccEnv_AllNameSpaces`, which calls
`nonDetEltsUFM` and returns the results in an order depending on
uniques.
Sorting the list with a stable sort before returning the interface makes
the output deterministic and follows the approach taken by other fields
in `Docs`.
Fixes #26858
-
89898ce6
by echoumcp1 at 2026-02-09T17:30:01-05:00
Replace putstrln with logMsg in handleSeqHValueStatus
Fixes #26549
-
7c52c4f9
by John Paul Adrian Glaubitz at 2026-02-10T13:52:43-05:00
rts: Switch prim to use modern atomic compiler builtins
The __sync_*() atomic compiler builtins have been deprecated in GCC
for a while now and also don't provide variants for 64-bit values
such as __sync_fetch_and_add_8().
Thus, replace them with the modern __atomic_*() compiler builtins and
while we're at it, also drop the helper macro CAS_NAND() which is now
no longer needed since we stopped using the __sync_*() compiler builtins
altogether.
Co-authored-by: Ilias Tsitsimpis <iliastsi@debian.org>
Fixes #26729
-
cf60850a
by Recursion Ninja at 2026-02-10T13:53:27-05:00
Decoupling L.H.S.Decls from GHC.Types.ForeignCall
- Adding TTG extension point for 'CCallTarget'
- Adding TTG extension point for 'CType'
- Adding TTG extension point for 'Header'
- Moving ForeignCall types that do not need extension
to new L.H.S.Decls.Foreign module
- Replacing 'Bool' parameters with descriptive data-types
to increase clairty and prevent "Boolean Blindness"
-
11a04cbb
by Eric Lee at 2026-02-11T09:20:46-05:00
Derive Semigroup/Monoid for instances believed could be derived in #25871
-
15d9ce44
by Eric Lee at 2026-02-11T09:20:46-05:00
add Ghc.Data.Pair deriving
-
c85dc170
by Evan Piro at 2026-02-11T09:21:45-05:00
Linker.MacOS reduce options import
-
a541dd83
by Chris Wendt at 2026-02-11T16:06:41-05:00
Initialize plugins for `:set +c` in GHCi
Fixes #23110.
-
0f5a73bc
by Cheng Shao at 2026-02-11T16:07:27-05:00
compiler: add Binary Text instance
This patch adds `Binary` instance for strict `Text`, in preparation of
making `Text` usable in certain GHC API use cases (e.g. haddock). This
also introduces `text` as a direct dependency of the `ghc` package.
-
9e58b8a1
by Cheng Shao at 2026-02-11T16:08:10-05:00
ghc-toolchain: add C11 check
This patch partially reverts commit
b8307eab80c5809df5405d76c822bf86877f5960 that removed C99 check in
autoconf/ghc-toolchain. Now we:
- No longer re-implement `FP_SET_CFLAGS_C11` similar to
`FP_SET_CFLAGS_C99` in the past, since autoconf doesn't provide a
convenient `AC_PROG_CC_C11` function. ghc-toolchain will handle it
anyway.
- The Cmm CPP C99 check is relanded and repurposed for C11.
- The C99 logic in ghc-toolchain is relanded and repurposed for C11.
- The C99 check in Stg.h is corrected to check for C11. The obsolete
_ISOC99_SOURCE trick is dropped.
- Usages of `-std=gnu99` in the testsuite are corrected to use
`-std=gnu11`.
Closes #26908.
-
694defb0
by Duncan Coutts at 2026-02-11T22:48:32+00:00
Move THREADED_RTS-conditional struct members to end of Capability
Accessing members of the Capability struct from CMM code rely on
accessor macros. (The macros are generated by deriveConstants).
These macros have a single definition. This means that the offsets of
all struct members must *not* vary based on THREADED_RTS vs
!THREADED_RTS. This requires that any struct members that are
conditional on THREADED_RTS must occur after the unconditional struct
members. Hence we move all the ones that are conditional on
THREADED_RTS to the end.
Add a deriveConstants entry for the iomgr member of the Capability
struct, which was the motivation for this change.
Add warning messages to help our future selves. Debugging this took me
a couple hours in gdb!
-
f340f464
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Make the IOManager API use CapIOManager rather than Capability
This makes the API somewhat more self-contained and more consistent.
Now the IOManager API and each of the backends takes just the I/O
manager structure. Previously we had a bit of a mixture, depending on
whether the function needed access to the Capability or just the
CapIOManager.
We still need access to the cap, so we introduce a back reference to
reach the capability, via iomgr->cap.
Convert all uses in select and poll backends, but not win32 ones.
Convert callers in the scheduler and elsewhere.
Also convert the three CMM primops that call IOManager APIs. They just
need to use Capability_iomgr(MyCapability()).
-
65ddbeb8
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Split posix/MIO.c out of posix/Signals.c
The MIO I/O manager was secretly living inside the Signals file.
Now it gets its own file, like any other self-respecting I/O manager.
-
938ca0da
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Rationalise some scheduler run queue utilities
Move them all to the same place in the file.
Make some static that were used only internally.
Also remove a redundant assignment after calling truncateRunQueue that
is already done within truncateRunQueue.
-
6d67a062
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Rename initIOManager{AfterFork} to {re}startIOManager
These are more accurate names, since these actions happen after
initialisation and are really about starting (or restarting) background
threads.
-
5fca4746
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Add a TODO to the MIO I/O manager
The direction of travel is to make I/O managers per-capability and have
all their state live in the struct CapIOManager. The MIO I/O manager
however still has a number of global variables.
It's not obvious how handle these globals however.
-
13657907
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Free per-cap I/O managers during shutdown and forkProcess
Historically this was not strictly necessary. The select and win32
legacy I/O managers did not maintain any dynamically allocated
resources. The new poll one does (an auxillary table), and so this
should be freed.
After forkProcess, all threads get deleted. This includes threads
waiting on I/O or timers. So as of this patch, resetting the I/O
manager is just about tidying things up. For example, for the poll
I/O manager this will reset the size of the AIOP table (which
otherwise grows but never shrinks).
In future however the re-initialising will become neeecessary for
functionality, since some I/O managers will need to re-initialise
wakeup fds that are set CLOEXEC.
-
8a1bff55
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Add an FdWakup module for posix I/O managers
This will be used to implement wakeupIOManager for in-RTS I/O managers.
It provides a notification/wakeup mechanism using FDs, suitable for
situations when I/O managers are blocked on a set of fds anyway.
-
e874ac1e
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Add wakeupIOManager support for select I/O manager
Uses the FdWakup mechanism.
-
d386ca39
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Add wakeupIOManager support for poll I/O manager
Uses the FdWakup mechanism.
A quirk we have to cope with is that we now need to poll one more fd --
the wakeup_fd_r -- but this fd has no corresponding entry in the
aiop_table. This is awkward since we have set up our aiop_poll_table to
be an auxilliary table with matching indicies.
The solution this patch uses (and described in the comments) is to have
two tables: struct pollfd *aiop_poll_table, *full_poll_table;
and to have the aiop_poll_table alias the tail of the full_poll_table.
The head entry in the full_poll_table is the extra fd. So we poll the
full_poll_table, while the aiop_poll_table still has matching indicies
with the aiop_table.
Hurrah for C aliasing rules.
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ddf53864
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Add wakeupIOManager support for win32 legacy I/O manager
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7823f045
by Duncan Coutts at 2026-02-11T22:48:35+00:00
wakeupIOManager is now required for all I/O managers
We are going to rely on it. Previously it could be a no-op. Update the
docs in the header file.
Also, temporarily disable awaitCompletedTimeoutsOrIO post-condition
assertion. It will become more complicated due to wakeupIOManager, and
it's not yet clear how to express it.
We will re-introduce a post condition after a few more changes.
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e0d12403
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Make signal handling be a respondibility of the I/O manager(s)
Previously it was scattered between I/O managers and the scheduler, and
especially the scheduler's deadlock detection.
Previously the scheduler would poll for pending signals each iteration
of the scheduler loop. The scheduler also had some hairy signal
functionality in the deadlock detection: in the non-threaded RTS (only)
if there were still no threads running after deadlock detection then it
would block waiting for signals.
But signals can and (in my opinion) should be thought of as just a funny
kind of I/O, and thus should be a responsibility of the I/O manager.
So now we have the I/O managers poll for signals when they are polling
for I/O completion (and removing the separate poll in the scheduler).
And when I/O managers block waiting for I/O then they now also start
signal handlers if they get interrupted by a signal. Crucially, if there
is no pending I/O or timers, the awaitCompletedTimeoutsOrIO will still
block waiting for signals.
This patch puts us into an intermediate state: it temporarily breaks
deadlock detection in the non-threaded RTS. The waiting on I/O currently
happens before deadlock detection. This means we'll now wait forever on
signals before doing deadlock detection. We need to move waiting after
deadlock detection. We'll do that in a later patch.
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0a0ae21f
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Clean up signal handling internal API
Now that the I/O manager is responsible for signals, we can simplify the
API we present for signal handling.
We now just need startPendingSignalHandlers, which is called from the
I/O managers. We can get rid of awaitUserSignals. We also don't need
RtsSignals.h to re-export the platform-specific posix/Signals.h or
win32/ConsoleHandler.h
We can also hide more of the implementation of signals. Less has to be
exposed in posix/Signals.h or win32/ConsoleHandler.h. Partly this is
because we don't need inline functions (or macros) in the interface.
Also remove signal_handlers from RTS ABI exported symbols list. It does
not appear to have any users in the core libs, and its really an
internal implementation detail. It should not be exposed unless its
really necessary.
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88c369ef
by Duncan Coutts at 2026-02-11T22:48:35+00:00
In the scheduler, move I/O blocking after deadlock detection
To make deadlock detection effective in the non-threaded RTS when there
are deadlocked threads and other unrelated threads waiting on I/O, we
need to arrange to do deadlock detection before we block in scheduler
to wait on I/O.
The solution is to:
1. adjust scheduleFindWork, which runs before deadlock detection, to
only poll for I/O and not block; and
2. add a step after deadlock detection to wait on I/O if there are
still no threads to run (and there's any I/O or timeouts outstanding)
The scheduleCheckBlockedThreads is now so simple that it made more sense
to inline it into scheduleFindWork.
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c46c875c
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Remove bogus anyPendingTimeoutsOrIO guard from scheduleDetectDeadlock
The deadlock detection was only invoked if both of these conditions
hold:
1. the run queue is empty
2. there is no pending I/O or timeouts
The second condition is unnecessary. The deadlock detection mechanism
can find deadlocks even if there are other threads waiting on I/O or
timers. Having this extra condition means that we fail to detect
blocked threads if there are any threads waiting on I/O or timers.
Part of fixing issue #26408
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549c5ecf
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Don't consider pending I/O for early context switch optimisation
Context switches are normally initiated by the timer signal. If however
the user specifies "context switch as often as possible", with +RTS -C0
then the scheduler arranges for an early context switch (when it's just
about to run a Haskell thread).
Context switching very often is expensive, so as an optimisation there
cases where we do not arrange an early context switch:
1. if there's no other threads to run
2. if there is no pending I/O or timers
This patch eliminates case 2, leaving only case 1.
The rationale is as follows. The use of this was inconsistent across
platforms and threaded/non-threaded RTS ways. It only worked on the
non-threaded RTS and on Windows only worked for the win32-legacy I/O
manager. On all other combinations anyPendingTimeoutsOrIO would always
return false. The fact that nobody noticed and complained about this
inconsistency suggests that the feature is not relied upon.
If however it turns out that applications do rely on this, then the
proper thing to do is not to restore this check, but to add a new I/O
manager hint function that returns if there is any pending events that
are likely to happen *soon*: for example timeouts expiring within one
timeslice, or I/O waits on things likely to complete soon like disk I/O,
but not for example socket/pipe I/O.
The motivation to avoid this use of anyPendingTimeoutsOrIO is to
allow us to eliminate anyPendingTimeoutsOrIO entirely. All other uses
of this are just guards on {await,poll}CompletedTimeoutsOrIO and
the guards can safely be folded into those functions. This will better
cope with some I/O managers having no proper implementation of
anyPendingTimeoutsOrIO.
Ultimately this will let us simplify the scheduler which currently has
to have special #ifdef mingw32_HOST_OS cases to cope with the lack of a
working anyPendingTimeoutsOrIO for some Windows I/O managers
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6d4e7580
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Remove anyPendingTimeoutsOrIO guarding {poll,await}CompletedTimeoutsOrIO
Previously the API of the I/O manager used a two step process: check
anyPendingTimeoutsOrIO and then call {poll,await}CompletedTimeoutsOrIO.
This was primarily there as a performance thing, to cheaply check if we
need to do anything.
And then because anyPendingTimeoutsOrIO existed, it was used for other
things too. We have now eliminated the other uses, and are just left
with the performance pattern.
But this was problematic because not all I/O managers correctly
implement anyPendingTimeoutsOrIO (specifically the win32 ones), and now
that we also make I/O managers responsible for signals then we need to
poll/await even if there is no pending I/O or timeouts. If there is no
pending I/O or timeouts then poll/await needs to degenerate to just
waiting forever for any signals.
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16255c2b
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Remove anyPendingTimeoutsOrIO, it is no longer used
And this avoids the problems arising from the win32 I/O managers having
had a bogus implementation.
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99ec95da
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Remove second scheduler call to awaitCompletedTimeoutsOrIO
Previously awaitCompletedTimeoutsOrIO was called both before and after
deadlock detection in the scheduler. The reason for that was that the
win32 I/O managers had a bogus implementation of anyPendingTimeoutsOrIO
and this was used to guard the call of awaitCompletedTimeoutsOrIO prior
to deadlock detection. This meant the first call site was never actually
called when using the win32 I/O managers. This was the reason for the
second call: the first one was never used. What a mess.
So now we have a simple design in the scheduler:
1. poll for completed I/O, timers or signals
2. if no runnable threads: do deadlock detection
3. if still no runnable threads: block waiting for I/O, timers or
signals.
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2f6f6b4f
by Duncan Coutts at 2026-02-11T22:48:35+00:00
Lift emptyRunQueue guard out of scheduleDetectDeadlock
this improved the clarity of the logic when reading the scheduler code.
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8ed45f42
by Duncan Coutts at 2026-02-11T22:48:36+00:00
Make non-threaded deadlock detection also rely on idle GC
Only do deadlock detection GC when idle GC kicks in. This also relies on
using wakeUpRts, so now do this unconditionally. Previously wakeUpRts
was for the threaded rts only.
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010330a2
by Duncan Coutts at 2026-02-11T22:48:36+00:00
Enable idle GC by default on non-threaded RTS.
The behaviour is now uniform between threaded and non-threaded. The
deadlock detection now relies on idle GC for both threaded and
non-threaded ways. Previously deadlock detection did not rely on idle
GC for the non-threaded way.
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a3fb335b
by Duncan Coutts at 2026-02-11T22:48:36+00:00
Add a long Note [Deadlock detection]
It describes the historical and modern designs and their trade-offs.
The point is we've now unified the code for deadlock detection between
the threaded and non-threaded ways, by changing the non-threaded to
follow the same design as the threaded.
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8e281e15
by Duncan Coutts at 2026-02-11T22:48:36+00:00
Add a test for deadlock detection, issue #26408
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89687a43
by Duncan Coutts at 2026-02-11T22:48:36+00:00
Update the user guide with the revised idle GC behaviour
i.e. it's now not just for the threaded RTS, but general.
Also document the fact that disabling idle GC also disables deadlock
detection.