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[Git][ghc/ghc][wip/ani/tc-expand] Fixes from Simon [skip ci]
by Simon Peyton Jones (＠simonpj) 26 Mar '26

26 Mar '26

Simon Peyton Jones pushed to branch wip/ani/tc-expand at Glasgow Haskell Compiler / GHC Commits: 87447590 by Simon Peyton Jones at 2026-03-26T13:04:10+00:00 Fixes from Simon [skip ci] ..need documentation. - - - - - 7 changed files: - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Gen/Match.hs - compiler/GHC/Tc/Utils/TcMType.hs - compiler/GHC/Tc/Utils/TcType.hs - compiler/GHC/Tc/Utils/Unify.hs Changes: ===================================== compiler/GHC/Tc/Gen/App.hs ===================================== @@ -1915,8 +1915,12 @@ quickLookArg1 pos app_lspan (fun, fun_lspan) larg@(L _ arg) sc_arg_ty@(Scaled _ -- generated by calls in arg do { ((rn_fun_arg, fun_lspan_arg), rn_args) <- splitHsApps arg + ; if tooComplicatedForQuickLook rn_fun_arg + then skipQuickLook app_lspan larg sc_arg_ty + else + -- Step 1: get the type of the head of the argument - ; (fun_ue, (tc_fun_arg_head, fun_sigma_arg_head)) <- tcCollectingUsage $ tcInferExprSigma rn_fun_arg + do { (fun_ue, (tc_fun_arg_head, fun_sigma_arg_head)) <- tcCollectingUsage $ tcInferExprSigma rn_fun_arg -- tcCollectingUsage: the use of an Id at the head generates usage-info -- See the call to `tcEmitBindingUsage` in `check_local_id`. So we must -- capture and save it in the `EValArgQL`. See (QLA6) in @@ -1978,7 +1982,7 @@ quickLookArg1 pos app_lspan (fun, fun_lspan) larg@(L _ arg) sc_arg_ty@(Scaled _ , eaql_wanted = wanted , eaql_encl = arg_influences_enclosing_call , eaql_res_rho = app_res_rho }) - } + }} mk_origin :: SrcSpan -- SrcSpan of the function @@ -1999,6 +2003,16 @@ mk_origin fun_lspan rn_fun } +tooComplicatedForQuickLook :: HsExpr GhcRn -> Bool +tooComplicatedForQuickLook expr + = case expr of + HsVar {} -> False + ExprWithTySig {} -> False + XExpr (HsRecSelRn {}) -> False + HsOverLit {} -> False + _ -> True -- Too complicated + + {- ********************************************************************* * * Folding over instantiation variables ===================================== compiler/GHC/Tc/Gen/Expr.hs ===================================== @@ -323,6 +323,7 @@ tcExpr :: HsExpr GhcRn -- Se Note [Typechecking by expansion: overview] tcExpr e@(HsVar _ v_rn) res_ty = do { (v_tc, sigma_ty) <- tcInferId v_rn + ; traceTc "tcExpr:HsVar" (ppr v_tc <+> dcolon <+> ppr sigma_ty $$ ppr res_ty) ; tcWrapResult e v_tc sigma_ty res_ty } tcExpr e@(ExprWithTySig _ e_rn e_ty) res_ty @@ -545,8 +546,9 @@ tcExpr (HsCase ctxt scrut matches) res_ty tcExpr (HsIf x pred b1 b2) res_ty = do { pred' <- tcCheckMonoExpr pred boolTy - ; (u1,b1') <- tcCollectingUsage $ tcMonoLExpr b1 res_ty - ; (u2,b2') <- tcCollectingUsage $ tcMonoLExpr b2 res_ty + ; let res_ty' = adjustExpTypeForCaseBranches res_ty [b1,b2] + ; (u1,b1') <- tcCollectingUsage $ tcMonoLExpr b1 res_ty' + ; (u2,b2') <- tcCollectingUsage $ tcMonoLExpr b2 res_ty' ; tcEmitBindingUsage (supUE u1 u2) ; return (HsIf x pred' b1' b2') } ===================================== compiler/GHC/Tc/Gen/Head.hs ===================================== @@ -232,6 +232,7 @@ splitHsApps e = go e noSrcSpan [] go (HsAppType _ (L l fun) ty) lspan args = go fun (locA l) (mkETypeArg lspan ty : args) go (HsApp _ (L l fun) arg) lspan args = go fun (locA l) (mkEValArg lspan arg : args) +{- -- See Note [Looking through Template Haskell splices in splitHsApps] go e@(HsUntypedSplice splice_res splice) _ args = do { fun <- getUntypedSpliceBody splice_res @@ -242,6 +243,7 @@ splitHsApps e = go e noSrcSpan [] HsUntypedSpliceExpr _ (L l _) -> locA l -- l :: SrcAnn AnnListItem HsQuasiQuote _ _ (L l _) -> locA l -- l :: SrcAnn NoEpAnns (XUntypedSplice (HsImplicitLiftSplice _ _ _ (L l _))) -> locA l +-} -- See Note [Desugar OpApp in the typechecker] go e@(OpApp _ arg1 (L l op) arg2) _ args @@ -342,6 +344,8 @@ where Note [Looking through ExpandedThingRn] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +**** TODO **** this note is out of date. Fix me. + When creating an application chain in splitHsApps, we must deal with ExpandedThingRn f1 (f `HsApp` e1) `HsApp` e2 `HsApp` e3 ===================================== compiler/GHC/Tc/Gen/Match.hs ===================================== @@ -219,10 +219,10 @@ tcMatches :: (AnnoBody body, Outputable (body GhcTc)) -> MatchGroup GhcRn (LocatedA (body GhcRn)) -> TcM (MatchGroup GhcTc (LocatedA (body GhcTc))) -tcMatches ctxt tc_body pat_tys rhs_ty (MG { mg_alts = L l matches +tcMatches ctxt tc_body pat_tys exp_ty (MG { mg_alts = L l matches , mg_ext = origin }) | null matches -- Deal with case e of {} - -- Since there are no branches, no one else will fill in rhs_ty + -- Since there are no branches, no one else will fill in exp_ty -- when in inference mode, so we must do it ourselves, -- here, using expTypeToType = do { tcEmitBindingUsage bottomUE @@ -233,17 +233,19 @@ tcMatches ctxt tc_body pat_tys rhs_ty (MG { mg_alts = L l matches [ExpForAllPatTy tvb] -> failWithTc $ TcRnEmptyCase ctxt (EmptyCaseForall tvb) [] -> panic "tcMatches: no arguments in EmptyCase" _t1:(_t2:_ts) -> panic "tcMatches: multiple arguments in EmptyCase" - ; rhs_ty <- expTypeToType rhs_ty + ; rhs_ty <- expTypeToType exp_ty ; return (MG { mg_alts = L l [] , mg_ext = MatchGroupTc [pat_ty] rhs_ty origin }) } | otherwise - = do { umatches <- mapM (tcCollectingUsage . tcMatch tc_body pat_tys rhs_ty) matches - ; let (usages, matches') = unzip umatches + = do { let exp_ty' = adjustExpTypeForCaseBranches exp_ty matches + tc_match match = tcCollectingUsage $ + tcMatch tc_body pat_tys exp_ty' match + ; (usages, matches') <- mapAndUnzipM tc_match matches ; tcEmitBindingUsage $ supUEs usages ; pat_tys <- mapM readScaledExpType (filter_out_forall_pat_tys pat_tys) - ; rhs_ty <- readExpType rhs_ty + ; rhs_ty <- readExpType exp_ty' ; traceTc "tcMatches" (ppr matches' $$ ppr pat_tys $$ ppr rhs_ty) ; return (MG { mg_alts = L l matches' , mg_ext = MatchGroupTc pat_tys rhs_ty origin ===================================== compiler/GHC/Tc/Utils/TcMType.hs ===================================== @@ -63,7 +63,7 @@ module GHC.Tc.Utils.TcMType ( mkCheckExpType, newInferExpType, newInferExpTypeFRR, runInfer, runInferRho, runInferSigma, runInferKind, runInferRhoFRR, runInferSigmaFRR, readExpType, readExpType_maybe, readScaledExpType, - expTypeToType, scaledExpTypeToType, + expTypeToType, scaledExpTypeToType, adjustExpTypeForCaseBranches, checkingExpType_maybe, checkingExpType, inferResultToType, ensureMonoType, promoteTcType, @@ -499,6 +499,17 @@ inferResultToType (IR { ir_uniq = u, ir_lvl = tc_lvl ; let conc_orig = ConcreteFRR $ FixedRuntimeRepOrigin tau frr ; return tau } +adjustExpTypeForCaseBranches :: ExpRhoType -> [branch] -> ExpRhoType +-- See Note [fillInferResult: multiple branches] +adjustExpTypeForCaseBranches exp_ty branches + = case exp_ty of + Infer ir | IR { ir_inst = IIF_Sigma } <- ir + , branches `lengthAtLeast` 2 + -> Infer (ir { ir_inst = IIF_DeepRho }) + | otherwise + -> exp_ty + Check {} -> exp_ty + {- Note [inferResultToType] ~~~~~~~~~~~~~~~~~~~~~~~~~~~ expTypeToType and inferResultType convert an InferResult to a monotype. ===================================== compiler/GHC/Tc/Utils/TcType.hs ===================================== @@ -441,11 +441,12 @@ data InferInstFlag -- Specifies whether the inference should return an uninstan | IIF_ShallowRho -- Trying to infer a shallow RhoType (no foralls or => at the top) -- Top-instantiate (only, regardless of DeepSubsumption) before filling the hole - -- Typically used when inferring the type of an expression + -- Used only for view patterns; see Note [View patterns and polymorphism] | IIF_DeepRho -- Trying to infer a possibly-deep RhoType (depending on DeepSubsumption) -- If DeepSubsumption is off, same as IIF_ShallowRho -- If DeepSubsumption is on, instantiate deeply before filling the hole + -- Typically used when inferring the type of an expression type ExpSigmaType = ExpType type ExpRhoType = ExpType ===================================== compiler/GHC/Tc/Utils/Unify.hs ===================================== @@ -1197,13 +1197,15 @@ There are two things to worry about: 1. What if it is under a GADT or existential pattern match? - GADTs: a unification variable (and Infer's hole is similar) is untouchable - Existentials: be careful about skolem-escape + See Note [fillInferResult: GADTs and existentials] 2. What if it is filled in more than once? E.g. multiple branches of a case case e of T1 -> e1 T2 -> e2 + See Note [fillInferResult: multiple branches] -Our typing rules are: +In general our typing rules are: * The RHS of a existential or GADT alternative must always be a monotype, regardless of the number of alternatives. @@ -1218,17 +1220,13 @@ Our typing rules are: We use choice (2) in that Section. (GHC 8.10 and earlier used choice (1).) - But note that - case e of - True -> hr - False -> \x -> hr x - will fail, because we still /infer/ both branches, so the \x will get - a (monotype) unification variable, which will fail to unify with - (forall a. a->a) +Note [fillInferResult: GADTs and existentials] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +We can detect the GADT/existential situation, case (1) of Note [fillInferResult], +by seeing that the current TcLevel is greater than that stored in ir_lvl of the +Infer ExpType. We bump the level whenever we go past a GADT/existential match. -For (1) we can detect the GADT/existential situation by seeing that -the current TcLevel is greater than that stored in ir_lvl of the Infer -ExpType. We bump the level whenever we go past a GADT/existential match. +We insist that the RHS has a monotype, regardless of the number of alternatives. Then, before filling the hole use promoteTcType to promote the type to the outer ir_lvl. promoteTcType does this @@ -1239,11 +1237,6 @@ That forces the type to be a monotype (since unification variables can only unify with monotypes); and catches skolem-escapes because the alpha is untouchable until the equality floats out. -For (2), we simply look to see if the hole is filled already. - - if not, we promote (as above) and fill the hole - - if it is filled, we simply unify with the type that is - already there - (FIR1) There is one wrinkle. Suppose we have case e of T1 -> e1 :: (forall a. a->a) -> Int @@ -1258,7 +1251,36 @@ For (2), we simply look to see if the hole is filled already. So if we check G2 second, we still want to emit a constraint that restricts the RHS to be a monotype. This is done by ensureMonoType, and it works by simply generating a constraint (alpha ~ ty), where alpha is a fresh -unification variable. We discard the evidence. + unification variable. We discard the evidence. + +Note [fillInferResult: multiple branches] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +If there are multiple case branches, case (2) of Note [fillInferResult] +we simply look to see if the hole is filled already. + - if not, we promote (as above) and fill the hole + - if it is filled, we simply unify with the type that is already there + +But consider + case x of + True -> True + False -> error "urk" +and suppose we call `tcInferSigma` on this expression, so that the `ir_inst` +field of the expected result type is `IIF_Sigma`. The danger is that we'll +fill the hole with `Bool` (from the `True`) and then reject when we try to +unify that with `forall a. a->a`, from the call to `error`. + +To avoid this, we never infer a sigma-type from a multi-branch `case`. Instead +we just zap the `IIF_Sigma` to `IIF_DeepRho` when walking inside the branches +of multi-arm case-expression, or an if-expression. See calls to +`adjustExpTypeForCaseBranches`. + +Note that + case e of + True -> hr + False -> \x -> hr x + where hr :: (forall a. a->a) -> Int +will fail, because we still /infer/ both branches, so the \x will get a +(monotype) unification variable, which will fail to unify with (forall a. a->a) Note [Instantiation of InferResult] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -1316,7 +1338,7 @@ HOWEVER, not always! Here are places where we want `IIF_Sigma` meaning but /not/ deeply instantiate (#26331). See Note [View patterns and polymorphism] in GHC.Tc.Gen.Pat. This the only place we use IIF_ShallowRho. -Why do we want to deeply instantiate, ever? Why isn't top-instantiation enough? +Why do we want to /deeply/ instantiate, ever? Why isn't top-instantiation enough? Answer: to accept the following program (T26225b) with -XDeepSubsumption, we need to deeply instantiate when inferring in checkResultTy: View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/87447590958fad8c6209f444140b6f0… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/87447590958fad8c6209f444140b6f0… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/ipe-interpreter-test] 59 commits: Introduce `-fimport-loaded-targets` GHCi flag
by Hannes Siebenhandl (＠fendor) 26 Mar '26

26 Mar '26

Hannes Siebenhandl pushed to branch wip/ipe-interpreter-test at Glasgow Haskell Compiler / GHC Commits: 86bd9bfc by fendor at 2026-03-17T23:46:09-04:00 Introduce `-fimport-loaded-targets` GHCi flag This new flag automatically adds all loaded targets to the GHCi session by adding an `InteractiveImport` for the loaded targets. By default, this flag is disabled, as it potentially increases memory-usage. This interacts with the flag `-fno-load-initial-targets` as follows: * If no module is loaded, no module is added as an interactive import. * If a reload loads up to a module, all loaded modules are added as interactive imports. * Unloading modules removes them from the interactive context. Fixes #26866 by rendering the use of a `-ghci-script` to achieve the same thing redundant. - - - - - e3d4c1bb by mniip at 2026-03-17T23:47:03-04:00 ghc-internal: Remove GHC.Internal.Data.Eq It served no purpose other than being a re-export. - - - - - 6f4f6cf0 by mniip at 2026-03-17T23:47:03-04:00 ghc-internal: Refine GHC.Internal.Base imports Removed re-exports from GHC.Internal.Base. This reveals some modules that don't actually use anything *defined* in GHC.Internal.Base, and that can be pushed down a little in the import graph. Replaced most imports of GHC.Internal.Base with non-wildcard imports from modules where the identifiers are actually defined. Part of #26834 Metric Decrease: T5321FD - - - - - 7fb51f54 by mangoiv at 2026-03-17T23:48:00-04:00 ci: clone, don't copy when creating the cabal cache Also removed WINDOWS_HOST variable detected via uname - we now just check whether the CI job has windows in its name. This works because we only ever care about it if the respective job is not a cross job. We also statically detect darwin cross jobs in the same way. We only ever have darwin -> darwin cross jobs so this is enough to detect the host reliably. - - - - - f8817879 by mangoiv at 2026-03-17T23:48:44-04:00 ci: mark size_hello_artifact fragile on darwin x86 The size of the x86_64 hello artifact is not stable which results in flaky testruns. Resolves #26814 - - - - - e34cb6da by Adam Gundry at 2026-03-20T12:20:00-04:00 ghci: Mention active language edition in startup banner Per GHC proposal 632, this makes the GHCi startup banner include the active language edition, plus an indication of whether this was the default (as opposed to being explicitly selected via an option such as `-XGHC2024`). For example: ``` $ ghci GHCi, version 9.14.1: https://www.haskell.org/ghc/ :? for help Using default language edition: GHC2024 ghci> ``` Fixes #26037. - - - - - 52c3e6ba by sheaf at 2026-03-20T12:21:09-04:00 Improve incomplete record selector warnings This commit stops GHC from emitting spurious incomplete record selector warnings for bare selectors/projections such as .fld There are two places we currently emit incomplete record selector warnings: 1. In the desugarer, when we see a record selector or an occurrence of 'getField'. Here, we can use pattern matching information to ensure we don't give false positives. 2. In the typechecker, which might sometimes give false positives but can emit warnings in cases that the pattern match checker would otherwise miss. This is explained in Note [Detecting incomplete record selectors] in GHC.HsToCore.Pmc. Now, we obviously don't want to emit the same error twice, and generally we prefer (1), as those messages contain fewer false positives. So we suppress (2) when we are sure we are going to emit (1); the logic for doing so is in GHC.Tc.Instance.Class.warnIncompleteRecSel, and works by looking at the CtOrigin. Now, the issue was that this logic handled explicit record selectors as well as overloaded record field selectors such as "x.r" (which turns into a simple GetFieldOrigin CtOrigin), but it didn't properly handle record projectors like ".fld" or ".fld1.fld2" (which result in other CtOrigins such as 'RecordFieldProjectionOrigin'). To solve this problem, we re-use the 'isHasFieldOrigin' introduced in fbdc623a (slightly adjusted). On the way, we also had to update the desugarer with special handling for the 'ExpandedThingTc' case in 'ds_app', to make sure that 'ds_app_var' sees all the type arguments to 'getField' in order for it to indeed emit warnings like in (1). Fixes #26686 - - - - - 309d7e87 by Cheng Shao at 2026-03-20T12:21:53-04:00 rts: opportunistically grow the MutableByteArray# in-place in resizeMutableByteArray# Following !15234, this patch improves `resizeMutableByteArray#` memory efficiency by growing the `MutableByteArray#` in-place if possible, addressing an old todo comment here. Also adds a new test case `resizeMutableByteArrayInPlace` that stresses this behavior. - - - - - 7d4ef162 by Matthew Craven at 2026-03-20T12:22:47-04:00 Change representation of floating point literals This commit changes the representation of floating point literals throughough the compiler, in particular in Core and Cmm. The Rational type is deficient for this purpose, dealing poorly with NaN, +/-Infinity, and negative zero. Instead, the new module GHC.Types.Literal.Floating uses the host Float/Double type to represent NaNs, infinities and negative zero. It also contains a Rational constructor, for the benefit of -fexcess-precision. Other changes: - Remove Note [negative zero] and related code This also removes the restrictions on constant-folding of division by zero, and should make any problems with NaN/Infinity more obvious. - Use -0.0 as the additive identity for Core constant folding rules for floating-point addition, fixing #21227. - Manual worker-wrapper for GHC.Float.rationalToDouble. This is intended to prevent the compiler's WW on this function from interfering with constant-folding. This change means that we now avoid allocating a box for the result of a 'realToFrac' call in T10359. - Combine floatDecodeOp and doubleDecodeOp. This change also fixes a bug in doubleDecodeOp wherein it would incorrectly produce an Int# instead of an Int64# literal for the mantissa component with 64-bit targets. - Use Float/Double for assembly immediates, and update the X86 and PowerPC backends to properly handle special values such as NaN and infinity. - Allow 'rational_to' to handle zero denominators, fixing a TODO in GHC.Core.Opt.ConstantFold. Fixes #8364 #9811 #18897 #21227 Progress towards #26919 Metric Decrease: T10359 Co-authored-by: sheaf <sam.derbyshire(a)gmail.com> ------------------------- Metric Decrease: T1969 T5321FD ------------------------- - - - - - 80e2dd4f by Zubin Duggal at 2026-03-20T12:23:33-04:00 compiler/ffi: Collapse void pointer chains in capi wrappers New gcc/clang treat -Wincompatible-pointer-types as an error by default. Since C only allows implicit conversion from void*, not void**, capi wrappers for functions taking e.g. abstract** would fail to compile when the Haskell type Ptr (Ptr Abstract) was naively translated to void**. Collapse nested void pointers to a single void* when the pointee type has no known C representation. Fixes #26852 - - - - - 1c50bd7b by Luite Stegeman at 2026-03-20T12:24:37-04:00 Move some functions related to pointer tagging to a separate module - - - - - bfd7aafd by Luite Stegeman at 2026-03-20T12:24:37-04:00 Branchless unpacking for enumeration types Change unpacking for enumeration types to go to Word8#/Word16#/Word# directly instead of going through an intermediate unboxed sum. This allows us to do a branchless conversion using DataToTag and TagToEnum. Fixes #26970 - - - - - 72b20fc0 by Luite Stegeman at 2026-03-20T12:25:30-04:00 bytecode: Carefully SLIDE off the end of a stack chunk The SLIDE bytecode instruction was not checking for stack chunk boundaries and could corrupt the stack underflow frame, leading to crashes. We add a check to use safe writes if we cross the chunk boundary and also handle stack underflow if Sp is advanced past the underflow frame. fix #27001 - - - - - 2e22b43c by Cheng Shao at 2026-03-20T12:26:14-04:00 ghci: serialize BCOByteArray buffer directly when possible This patch changes the `Binary` instances of `BCOByteArray` to directly serialize the underlying buffer when possible, while also taking into account the issue of host-dependent `Word` width. See added comments and amended `Note [BCOByteArray serialization]` for detailed explanation. Closes #27020. - - - - - 89d9ba37 by Sylvain Henry at 2026-03-20T12:27:34-04:00 JS: replace BigInt with Number arithmetic for 32/64-bit quot/rem (#23597) Replace BigInt-based implementations of quotWord32, remWord32, quotRemWord32, quotRem2Word32, quotWord64, remWord64, quotInt64, and remInt64 with pure Number (double/integer) arithmetic to avoid the overhead of BigInt promotion. - - - - - ae4ddd60 by Sylvain Henry at 2026-03-20T12:28:28-04:00 Core: add constant-folding rules for Addr# eq/ne (#18032) - - - - - 3e767f98 by Matthew Pickering at 2026-03-20T12:29:11-04:00 Use OsPath rather than FilePath in Downsweep cache This gets us one step closure to uniformly using `OsPath` in the compiler. - - - - - 2c57de29 by Cheng Shao at 2026-03-20T12:29:55-04:00 hadrian: fix ghc-in-ghci flavour stage0 shared libraries This patch fixes missing stage0 shared libraries in hadrian ghc-in-ghci flavour, which was accidentally dropped in 669d09f950a6e88b903d9fd8a7571531774d4d5d and resulted in a regression in HLS support on linux/macos. Fixes #27057. - - - - - 5b1be555 by Sylvain Henry at 2026-03-20T12:30:48-04:00 JS: install rts/Types.h header file (#27033) It was an omission, making HsFFI.h not usable with GHC using the JS backend. - - - - - b883f08f by Cheng Shao at 2026-03-20T12:31:33-04:00 hadrian: don't compile RTS with -Winline This patch removes `-Winline` from cflags when compiling the RTS, given that: 1. It generates a huge pile of spam and hurts developer experience 2. Whether inlining happens is highly dependent on toolchains, flavours, etc, and it's not really an issue to fix if inlining doesn't happen; it's a hint to the C compiler anyway. Fixes #27060. - - - - - 333387d6 by Cheng Shao at 2026-03-20T12:31:33-04:00 hadrian: compile libffi-clib with -Wno-deprecated-declarations This patch adds `-Wno-deprecated-declarations` to cflags of `libffi-clib`, given that it produces noise at compile-time that aren't really our issue to fix anyway, it's from vendored libffi source code. - - - - - 67c47771 by Rodrigo Mesquita at 2026-03-20T12:32:17-04:00 Expose decodeStackWithIpe from ghc-experimental This decoding is useful to the debugger and it wasn't originally exported as an oversight. - - - - - 18513365 by Matthew Pickering at 2026-03-21T04:43:26-04:00 Add support for custom external interpreter commands It can be useful for GHC API clients to implement their own external interpreter commands. For example, the debugger may want an efficient way to inspect the stacks of the running threads in the external interpreter. - - - - - 4636d906 by mangoiv at 2026-03-21T04:44:10-04:00 ci: remove obsolete fallback for old debian and ubuntu versions - - - - - 2e3a2805 by mangoiv at 2026-03-21T04:44:10-04:00 ci: drop ubuntu 18 and 20 Ubuntu 18 EOL: May 2023 Ubuntu 20 EOL: May 2025 We should probably not make another major release supporting these platforms. Also updates the generator script. Resolves #25876 - - - - - de54e264 by Cheng Shao at 2026-03-21T17:52:08+01:00 rts: fix -Wcompare-distinct-pointer-types errors This commit fixes `-Wcompare-distinct-pointer-types` errors in the RTS which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. - - - - - b9bd73de by Cheng Shao at 2026-03-21T17:52:08+01:00 ghc-internal: fix unused imports This commit fixes unused imports in `ghc-internal` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #26987 #27059. - - - - - da946a16 by Cheng Shao at 2026-03-21T17:03:51+00:00 ghci: fix unused imports This commit fixes unused imports in `ghci` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #26987 #27059. - - - - - 955b1cf8 by Cheng Shao at 2026-03-21T17:03:51+00:00 compiler: fix unused imports in GHC.Tc.Types.Origin This commit fixes unused imports in `GHC.Tc.Types.Origin` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #27059. - - - - - 3b1aeb50 by Cheng Shao at 2026-03-21T17:03:51+00:00 hadrian: fix missing +werror in validate flavour This patch fixes missing `+werror` in validate flavour, which was an oversight in bb3a2ba1eefadf0b2ef4f39b31337a23eec67f29. Fixes #27066. - - - - - 44f118f0 by Cheng Shao at 2026-03-22T04:54:01-04:00 ci: bump CACHE_REV and add the missing reminder This patch bumps `CACHE_REV` to address recent `[Cabal-7159]` CI errors due to stale cabal cache on some runners, and also adds a reminder to remind future maintainers. Fixes #27075. - - - - - 2a218737 by ARATA Mizuki at 2026-03-23T11:11:39-04:00 Add 128-bit SIMD support to AArch64 NCG Changes: - Add `Format` field to vector-capable instructions. These instructions will emit `vN.4s` (for example) as a operand. - Additional constructors for `Operand`: `OpVecLane` represents a vector lane and will be emitted as `vN.<width>[<index>]` (`vN.s[3]` for example). `OpScalarAsVec` represents a scalar, but printed as a vector lane like `vN.<width>[0]` (`vN.s[0]` for example). - Integer quot/rem are implemented in C, like x86. Closes #26536 Metric Increase: T3294 - - - - - 5d6e2be9 by ARATA Mizuki at 2026-03-23T11:11:39-04:00 AArch64 NCG: Improve code generation for floating-point and vector constants Some floating-point constants can be directly encoded using the FMOV instruction. Similarly, a class of vectors with same values can be encoded using FMOV, MOVI, or MVNI. - - - - - c6d262aa by Simon Jakobi at 2026-03-23T11:12:22-04:00 Add regression test for #13729 Closes #13729. - - - - - aa5dfe67 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - c8a7b588 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - a5ec467e by ARATA Mizuki at 2026-03-26T03:49:49-04:00 rts: Align stack to 64-byte boundary in StgRun on x86 When LLVM spills AVX/AVX-512 vector registers to the stack, it requires 32-byte (__m256) or 64-byte (__m512) alignment. If the stack is not sufficiently aligned, LLVM inserts a realignment prologue that reserves %rbp as a frame pointer, conflicting with GHC's use of %rbp as an STG callee-saved register and breaking the tail-call-based calling convention. Previously, GHC worked around this by lying to LLVM about the stack alignment and rewriting aligned vector loads/stores (VMOVDQA, VMOVAPS) to unaligned ones (VMOVDQU, VMOVUPS) in the LLVM Mangler. This had two problems: - It did not extend to AVX-512, which requires 64-byte alignment. (#26595) - When Haskell calls a C function that takes __m256/__m512 arguments on the stack, the callee requires genuine alignment, which could cause a segfault. (#26822) This patch genuinely aligns the stack to 64 bytes in StgRun by saving the original stack pointer before alignment and restoring it in StgReturn. We now unconditionally advertise 64-byte stack alignment to LLVM for all x86 targets, making rewriteAVX in the LLVM Mangler unnecessary. STG_RUN_STACK_FRAME_SIZE is increased from 48 to 56 bytes on non-Windows x86-64 to store the saved stack pointer. Closes #26595 and #26822 Co-Authored-By: Claude Opus 4.5 <noreply(a)anthropic.com> - - - - - 661da815 by Teo Camarasu at 2026-03-26T03:50:33-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - 45428f88 by sheaf at 2026-03-26T03:51:31-04:00 Avoid infinite loop in deep subsumption This commit ensures we only unify after we recur in the deep subsumption code in the FunTy vs non-FunTy case of GHC.Tc.Utils.Unify.tc_sub_type_deep, to avoid falling into an infinite loop. See the new Wrinkle [Avoiding a loop in tc_sub_type_deep] in Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify. Fixes #26823 Co-authored-by: simonpj <simon.peytonjones(a)gmail.com> - - - - - 2823b039 by Ian Duncan at 2026-03-26T03:52:21-04:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. - - - - - 57b7878d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12002 Closes #12002. - - - - - c8f9df2d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12046 Closes #12046. Co-authored-by: Andreas Klebinger <klebinger.andreas(a)gmx.at> - - - - - 615d72ac by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #13180 Closes #13180. - - - - - 423eebcf by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11141 Closes #11141. - - - - - 286849a4 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11505 Closes #11505. - - - - - 7db149d9 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression perf test for #13820 Closes #13820. - - - - - e73c4adb by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #10381 Closes #10381. - - - - - 5ebcfb57 by Benjamin Maurer at 2026-03-26T03:54:02-04:00 Generate assembly on x86 for word2float (#22252) We used to emit C function call for MO_UF_Conv primitive. Now emits direct assembly instead. Co-Authored-By: Sylvain Henry <sylvain(a)haskus.fr> Co-Authored-By: Claude Sonnet 4.6 <noreply(a)anthropic.com> - - - - - 5b550754 by Matthew Pickering at 2026-03-26T03:54:51-04:00 rts: forward clone-stack messages after TSO migration MSG_CLONE_STACK assumed that the target TSO was still owned by the capability that received the message. This is not always true: the TSO can migrate before the inbox entry is handled. When that happened, handleCloneStackMessage could clone a live stack from the wrong capability and use the wrong capability for allocation and performTryPutMVar, leading to stack sanity failures such as checkStackFrame: weird activation record found on stack. Fix this by passing the current capability into handleCloneStackMessage, rechecking msg->tso->cap at handling time, and forwarding the message if the TSO has migrated. Once ownership matches, use the executing capability consistently for cloneStack, rts_apply, and performTryPutMVar. Fixes #27008 - - - - - ef0a1bd2 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: adopt release tracking ticket from #16816 - - - - - a7f40fd9 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: add a release tracking ticket Brings the information in the release tracking ticket up to date with https://gitlab.haskell.org/ghc/ghc-hq/-/blob/main/release-management.mkd Resolves #26691 - - - - - 161d3285 by Teo Camarasu at 2026-03-26T03:56:18-04:00 Revert "Set default eventlog-flush-interval to 5s" Flushing the eventlog forces a synchronisation of all the capabilities and there was a worry that this might lead to a performance cost for some highly parallel workloads. This reverts commit 66b96e2a591d8e3d60e74af3671344dfe4061cf2. - - - - - 36eed985 by Cheng Shao at 2026-03-26T03:57:03-04:00 ghc-boot: move GHC.Data.SmallArray to ghc-boot This commit moves `GHC.Data.SmallArray` from the `ghc` library to `ghc-boot`, so that it can be used by `ghci` as well: - The `Binary` (from `ghc`) instance of `SmallArray` is moved to `GHC.Utils.Binary` - Util functions `replicateSmallArrayIO`, `mapSmallArrayIO`, `mapSmallArrayM_`, `imapSmallArrayM_` , `smallArrayFromList` and `smallArrayToList` are added - The `Show` instance is added - The `Binary` (from `binary`) instance is added - - - - - fdf828ae by Cheng Shao at 2026-03-26T03:57:03-04:00 compiler: use `Binary` instance of `BCOByteArray` for bytecode objects This commit defines `Binary` (from `compiler`) instance of `BCOByteArray` which serializes the underlying buffer directly, and uses it directly in bytecode object serialization. Previously we reuse the `Binary` (from `binary`) instance, and this change allows us to avoid double-copying via an intermediate `ByteString` when using `put`/`get` in `binnary`. Also see added comment for explanation. - - - - - 3bf62d0a by Cheng Shao at 2026-03-26T03:57:03-04:00 ghci: use SmallArray directly in ResolvedBCO This patch makes ghci use `SmallArray` directly in `ResolvedBCO` when applicable, making the memory representation more compact and reducing marshaling overhead. Closes #27058. - - - - - 3d6492ce by Wen Kokke at 2026-03-26T03:57:53-04:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. - - - - - 7b9a75f0 by Phil Hazelden at 2026-03-26T03:58:37-04:00 Fix build with werror on glibc 2.43. We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same values as defined in glibc prior to 2.43. But in 2.43, glibc changes them to new values, which means we get a warning when redefining them. By `#undef`ing them first, we no longer get a warning. Closes #27076. - - - - - fe6e76c5 by Tobias Haslop at 2026-03-26T03:59:30-04:00 Fix broken Haddock link to Bifunctor class in description of Functor class - - - - - df34af7e by Matthew Pickering at 2026-03-26T13:55:21+01:00 Add failing test for `-finfo-table-map` and bytecode backend If you compile a module using the bytecode backend, with -finfo-table-map, then the info table map doesn't get populated for the module. This is because the -finfo-table-map code path is implemented mostly in the StgToCmm phase which isn't run when creating bytecode. Ticket #27039 - - - - - 513 changed files: - .gitlab-ci.yml - .gitlab/ci.sh - .gitlab/generate-ci/flake.lock - .gitlab/generate-ci/gen_ci.hs - + .gitlab/issue_templates/release_tracking.md - .gitlab/jobs.yaml - .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/CodeGen.Platform.h - compiler/GHC/Builtin/Names.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Cmm/CommonBlockElim.hs - compiler/GHC/Cmm/Expr.hs - compiler/GHC/Cmm/Node.hs - compiler/GHC/Cmm/Opt.hs - compiler/GHC/Cmm/Parser.y - compiler/GHC/Cmm/Type.hs - compiler/GHC/Cmm/Utils.hs - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/AArch64/Ppr.hs - compiler/GHC/CmmToAsm/AArch64/Regs.hs - compiler/GHC/CmmToAsm/LA64/CodeGen.hs - compiler/GHC/CmmToAsm/LA64/Ppr.hs - compiler/GHC/CmmToAsm/LA64/Regs.hs - compiler/GHC/CmmToAsm/PPC/CodeGen.hs - compiler/GHC/CmmToAsm/PPC/Ppr.hs - compiler/GHC/CmmToAsm/PPC/Regs.hs - compiler/GHC/CmmToAsm/RV64/CodeGen.hs - compiler/GHC/CmmToAsm/RV64/Ppr.hs - compiler/GHC/CmmToAsm/RV64/Regs.hs - compiler/GHC/CmmToAsm/Reg/Graph/TrivColorable.hs - compiler/GHC/CmmToAsm/Wasm/FromCmm.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Ppr.hs - compiler/GHC/CmmToAsm/X86/Regs.hs - compiler/GHC/CmmToC.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/CodeGen.hs - compiler/GHC/CmmToLlvm/Config.hs - compiler/GHC/CmmToLlvm/Data.hs - compiler/GHC/CmmToLlvm/Mangler.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/Driver/Config/StgToCmm.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Foreign/C.hs - compiler/GHC/HsToCore/Match/Literal.hs - compiler/GHC/HsToCore/Pmc.hs - compiler/GHC/HsToCore/Pmc/Solver/Types.hs - + compiler/GHC/Platform/Tag.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/Stg/Unarise.hs - compiler/GHC/StgToByteCode.hs - compiler/GHC/StgToCmm/Closure.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Lit.hs - compiler/GHC/StgToCmm/Prim.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/StgToJS/Literal.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Instance/Class.hs - compiler/GHC/Tc/TyCl/Build.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Types/Id/Make.hs - compiler/GHC/Types/Literal.hs - + compiler/GHC/Types/Literal/Floating.hs - compiler/GHC/Types/RepType.hs - compiler/GHC/Utils/Binary.hs - compiler/ghc.cabal.in - docs/users_guide/9.16.1-notes.rst - docs/users_guide/ghci.rst - docs/users_guide/utils.py - ghc/GHCi/UI.hs - ghc/Main.hs - hadrian/cabal.project - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Flavours/Validate.hs - hadrian/src/Settings/Packages.hs - libraries/base/src/Control/Applicative.hs - libraries/base/src/Data/Char.hs - libraries/base/src/Data/Eq.hs - libraries/base/src/Data/Semigroup.hs - libraries/base/src/GHC/Base.hs - libraries/base/src/GHC/Weak/Finalize.hs - libraries/base/src/Prelude.hs - compiler/GHC/Data/SmallArray.hs → libraries/ghc-boot/GHC/Data/SmallArray.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-experimental/ghc-experimental.cabal.in - libraries/ghc-experimental/src/GHC/Profiling/Eras.hs - + libraries/ghc-experimental/src/GHC/Stack/Decode/Experimental.hs - libraries/ghc-internal/codepages/MakeTable.hs - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/AllocationLimitHandler.hs - libraries/ghc-internal/src/GHC/Internal/Arr.hs - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/Bits.hs - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Clock.hsc - libraries/ghc-internal/src/GHC/Internal/ClosureTypes.hs - libraries/ghc-internal/src/GHC/Internal/Conc/Bound.hs - libraries/ghc-internal/src/GHC/Internal/Conc/IO.hs - libraries/ghc-internal/src/GHC/Internal/Conc/POSIX.hs - libraries/ghc-internal/src/GHC/Internal/Conc/Signal.hs - libraries/ghc-internal/src/GHC/Internal/Conc/Sync.hs - libraries/ghc-internal/src/GHC/Internal/Conc/Windows.hs - libraries/ghc-internal/src/GHC/Internal/ConsoleHandler.hsc - libraries/ghc-internal/src/GHC/Internal/Control/Arrow.hs - libraries/ghc-internal/src/GHC/Internal/Control/Concurrent/MVar.hs - libraries/ghc-internal/src/GHC/Internal/Control/Exception.hs - libraries/ghc-internal/src/GHC/Internal/Control/Exception/Base.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/Fail.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/Fix.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/IO/Class.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Imp.hs - libraries/ghc-internal/src/GHC/Internal/Control/Monad/ST/Lazy/Imp.hs - libraries/ghc-internal/src/GHC/Internal/Data/Bits.hs - libraries/ghc-internal/src/GHC/Internal/Data/Data.hs - libraries/ghc-internal/src/GHC/Internal/Data/Dynamic.hs - libraries/ghc-internal/src/GHC/Internal/Data/Either.hs - − libraries/ghc-internal/src/GHC/Internal/Data/Eq.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Function.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Utils.hs - libraries/ghc-internal/src/GHC/Internal/Data/IORef.hs - libraries/ghc-internal/src/GHC/Internal/Data/List.hs - libraries/ghc-internal/src/GHC/Internal/Data/Maybe.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/OldList.hs - libraries/ghc-internal/src/GHC/Internal/Data/Ord.hs - libraries/ghc-internal/src/GHC/Internal/Data/Proxy.hs - libraries/ghc-internal/src/GHC/Internal/Data/STRef.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/String.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Type/Bool.hs - libraries/ghc-internal/src/GHC/Internal/Data/Type/Coercion.hs - libraries/ghc-internal/src/GHC/Internal/Data/Type/Equality.hs - libraries/ghc-internal/src/GHC/Internal/Data/Type/Ord.hs - libraries/ghc-internal/src/GHC/Internal/Data/Typeable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Typeable/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Unique.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Debug/Trace.hs - libraries/ghc-internal/src/GHC/Internal/Debug/Trace.hs-boot - libraries/ghc-internal/src/GHC/Internal/Encoding/UTF8.hs - libraries/ghc-internal/src/GHC/Internal/Enum.hs - libraries/ghc-internal/src/GHC/Internal/Environment.hs - libraries/ghc-internal/src/GHC/Internal/Event/Array.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Event/EPoll.hsc - libraries/ghc-internal/src/GHC/Internal/Event/IntVar.hs - libraries/ghc-internal/src/GHC/Internal/Event/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Event/Internal/Types.hs - libraries/ghc-internal/src/GHC/Internal/Event/KQueue.hsc - libraries/ghc-internal/src/GHC/Internal/Event/Manager.hs - libraries/ghc-internal/src/GHC/Internal/Event/PSQ.hs - libraries/ghc-internal/src/GHC/Internal/Event/Poll.hsc - libraries/ghc-internal/src/GHC/Internal/Event/Thread.hs - libraries/ghc-internal/src/GHC/Internal/Event/TimeOut.hs - libraries/ghc-internal/src/GHC/Internal/Event/TimerManager.hs - libraries/ghc-internal/src/GHC/Internal/Event/Unique.hs - libraries/ghc-internal/src/GHC/Internal/Event/Windows.hsc - 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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/a0d2657357211c62c047c015f9c39e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/a0d2657357211c62c047c015f9c39e… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/T27056] 26 commits: Check that shift values are valid
by Teo Camarasu (＠teo) 26 Mar '26

26 Mar '26

Teo Camarasu pushed to branch wip/T27056 at Glasgow Haskell Compiler / GHC Commits: aa5dfe67 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - c8a7b588 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - a5ec467e by ARATA Mizuki at 2026-03-26T03:49:49-04:00 rts: Align stack to 64-byte boundary in StgRun on x86 When LLVM spills AVX/AVX-512 vector registers to the stack, it requires 32-byte (__m256) or 64-byte (__m512) alignment. If the stack is not sufficiently aligned, LLVM inserts a realignment prologue that reserves %rbp as a frame pointer, conflicting with GHC's use of %rbp as an STG callee-saved register and breaking the tail-call-based calling convention. Previously, GHC worked around this by lying to LLVM about the stack alignment and rewriting aligned vector loads/stores (VMOVDQA, VMOVAPS) to unaligned ones (VMOVDQU, VMOVUPS) in the LLVM Mangler. This had two problems: - It did not extend to AVX-512, which requires 64-byte alignment. (#26595) - When Haskell calls a C function that takes __m256/__m512 arguments on the stack, the callee requires genuine alignment, which could cause a segfault. (#26822) This patch genuinely aligns the stack to 64 bytes in StgRun by saving the original stack pointer before alignment and restoring it in StgReturn. We now unconditionally advertise 64-byte stack alignment to LLVM for all x86 targets, making rewriteAVX in the LLVM Mangler unnecessary. STG_RUN_STACK_FRAME_SIZE is increased from 48 to 56 bytes on non-Windows x86-64 to store the saved stack pointer. Closes #26595 and #26822 Co-Authored-By: Claude Opus 4.5 <noreply(a)anthropic.com> - - - - - 661da815 by Teo Camarasu at 2026-03-26T03:50:33-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - 45428f88 by sheaf at 2026-03-26T03:51:31-04:00 Avoid infinite loop in deep subsumption This commit ensures we only unify after we recur in the deep subsumption code in the FunTy vs non-FunTy case of GHC.Tc.Utils.Unify.tc_sub_type_deep, to avoid falling into an infinite loop. See the new Wrinkle [Avoiding a loop in tc_sub_type_deep] in Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify. Fixes #26823 Co-authored-by: simonpj <simon.peytonjones(a)gmail.com> - - - - - 2823b039 by Ian Duncan at 2026-03-26T03:52:21-04:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. - - - - - 57b7878d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12002 Closes #12002. - - - - - c8f9df2d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12046 Closes #12046. Co-authored-by: Andreas Klebinger <klebinger.andreas(a)gmx.at> - - - - - 615d72ac by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #13180 Closes #13180. - - - - - 423eebcf by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11141 Closes #11141. - - - - - 286849a4 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11505 Closes #11505. - - - - - 7db149d9 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression perf test for #13820 Closes #13820. - - - - - e73c4adb by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #10381 Closes #10381. - - - - - 5ebcfb57 by Benjamin Maurer at 2026-03-26T03:54:02-04:00 Generate assembly on x86 for word2float (#22252) We used to emit C function call for MO_UF_Conv primitive. Now emits direct assembly instead. Co-Authored-By: Sylvain Henry <sylvain(a)haskus.fr> Co-Authored-By: Claude Sonnet 4.6 <noreply(a)anthropic.com> - - - - - 5b550754 by Matthew Pickering at 2026-03-26T03:54:51-04:00 rts: forward clone-stack messages after TSO migration MSG_CLONE_STACK assumed that the target TSO was still owned by the capability that received the message. This is not always true: the TSO can migrate before the inbox entry is handled. When that happened, handleCloneStackMessage could clone a live stack from the wrong capability and use the wrong capability for allocation and performTryPutMVar, leading to stack sanity failures such as checkStackFrame: weird activation record found on stack. Fix this by passing the current capability into handleCloneStackMessage, rechecking msg->tso->cap at handling time, and forwarding the message if the TSO has migrated. Once ownership matches, use the executing capability consistently for cloneStack, rts_apply, and performTryPutMVar. Fixes #27008 - - - - - ef0a1bd2 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: adopt release tracking ticket from #16816 - - - - - a7f40fd9 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: add a release tracking ticket Brings the information in the release tracking ticket up to date with https://gitlab.haskell.org/ghc/ghc-hq/-/blob/main/release-management.mkd Resolves #26691 - - - - - 161d3285 by Teo Camarasu at 2026-03-26T03:56:18-04:00 Revert "Set default eventlog-flush-interval to 5s" Flushing the eventlog forces a synchronisation of all the capabilities and there was a worry that this might lead to a performance cost for some highly parallel workloads. This reverts commit 66b96e2a591d8e3d60e74af3671344dfe4061cf2. - - - - - 36eed985 by Cheng Shao at 2026-03-26T03:57:03-04:00 ghc-boot: move GHC.Data.SmallArray to ghc-boot This commit moves `GHC.Data.SmallArray` from the `ghc` library to `ghc-boot`, so that it can be used by `ghci` as well: - The `Binary` (from `ghc`) instance of `SmallArray` is moved to `GHC.Utils.Binary` - Util functions `replicateSmallArrayIO`, `mapSmallArrayIO`, `mapSmallArrayM_`, `imapSmallArrayM_` , `smallArrayFromList` and `smallArrayToList` are added - The `Show` instance is added - The `Binary` (from `binary`) instance is added - - - - - fdf828ae by Cheng Shao at 2026-03-26T03:57:03-04:00 compiler: use `Binary` instance of `BCOByteArray` for bytecode objects This commit defines `Binary` (from `compiler`) instance of `BCOByteArray` which serializes the underlying buffer directly, and uses it directly in bytecode object serialization. Previously we reuse the `Binary` (from `binary`) instance, and this change allows us to avoid double-copying via an intermediate `ByteString` when using `put`/`get` in `binnary`. Also see added comment for explanation. - - - - - 3bf62d0a by Cheng Shao at 2026-03-26T03:57:03-04:00 ghci: use SmallArray directly in ResolvedBCO This patch makes ghci use `SmallArray` directly in `ResolvedBCO` when applicable, making the memory representation more compact and reducing marshaling overhead. Closes #27058. - - - - - 3d6492ce by Wen Kokke at 2026-03-26T03:57:53-04:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. - - - - - 7b9a75f0 by Phil Hazelden at 2026-03-26T03:58:37-04:00 Fix build with werror on glibc 2.43. We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same values as defined in glibc prior to 2.43. But in 2.43, glibc changes them to new values, which means we get a warning when redefining them. By `#undef`ing them first, we no longer get a warning. Closes #27076. - - - - - fe6e76c5 by Tobias Haslop at 2026-03-26T03:59:30-04:00 Fix broken Haddock link to Bifunctor class in description of Functor class - - - - - c3c10dc4 by Teo Camarasu at 2026-03-26T12:37:33+00:00 doc: improve eventlog-flush-interval flag documentation We mention the performance cost and how this flag can be turned off. Resolves #27056 - - - - - 57490e1f by Teo Camarasu at 2026-03-26T12:37:33+00:00 docs/user_guide: fix typo - - - - - 110 changed files: - + .gitlab/issue_templates/release_tracking.md - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Cmm/Node.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/Config.hs - compiler/GHC/CmmToLlvm/Mangler.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Utils/Binary.hs - compiler/ghc.cabal.in - docs/users_guide/9.16.1-notes.rst - docs/users_guide/runtime_control.rst - compiler/GHC/Data/SmallArray.hs → libraries/ghc-boot/GHC/Data/SmallArray.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/Generics.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/Read.hs - libraries/ghc-internal/src/GHC/Internal/Unicode/Bits.hs - libraries/ghci/GHCi/CreateBCO.hs - libraries/ghci/GHCi/ResolvedBCO.hs - rts/CloneStack.c - rts/CloneStack.h - rts/Messages.c - rts/RtsFlags.c - rts/StgCRun.c - rts/eventlog/EventLog.c - rts/include/rts/Constants.h - rts/include/rts/PosixSource.h - testsuite/tests/codeGen/should_run/Word2Float32.hs - testsuite/tests/codeGen/should_run/Word2Float32.stdout - testsuite/tests/codeGen/should_run/Word2Float64.hs - testsuite/tests/codeGen/should_run/Word2Float64.stdout - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/ghci/scripts/ListTuplePunsPpr.stdout - testsuite/tests/ghci/scripts/T10963.stderr - testsuite/tests/ghci/scripts/ghci064.stdout - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - + testsuite/tests/parser/should_compile/T12002.hs - + testsuite/tests/parser/should_compile/T12002.stderr - testsuite/tests/parser/should_compile/all.T - + testsuite/tests/perf/compiler/T13820.hs - testsuite/tests/perf/compiler/all.T - + testsuite/tests/rebindable/T10381.hs - testsuite/tests/rebindable/all.T - testsuite/tests/rts/all.T - + testsuite/tests/rts/cloneThreadStackMigrating.hs - + testsuite/tests/simd/should_run/StackAlignment32.hs - + testsuite/tests/simd/should_run/StackAlignment32.stdout - + testsuite/tests/simd/should_run/StackAlignment32_main.c - + testsuite/tests/simd/should_run/StackAlignment64.hs - + testsuite/tests/simd/should_run/StackAlignment64.stdout - + testsuite/tests/simd/should_run/StackAlignment64_main.c - testsuite/tests/simd/should_run/all.T - + testsuite/tests/simplCore/should_compile/T19166.hs - + testsuite/tests/simplCore/should_compile/T19166.stderr - + testsuite/tests/simplCore/should_compile/T25718.hs - + testsuite/tests/simplCore/should_compile/T25718.stderr - + testsuite/tests/simplCore/should_compile/T25718a.hs - + testsuite/tests/simplCore/should_compile/T25718a.stderr - + testsuite/tests/simplCore/should_compile/T25718b.hs - + testsuite/tests/simplCore/should_compile/T25718b.stderr - + testsuite/tests/simplCore/should_compile/T25718c.hs - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/all.T - + testsuite/tests/typecheck/T13180/T13180.hs - + testsuite/tests/typecheck/T13180/T13180.hs-boot - + testsuite/tests/typecheck/T13180/T13180.stderr - + testsuite/tests/typecheck/T13180/T13180A.hs - + testsuite/tests/typecheck/T13180/all.T - + testsuite/tests/typecheck/should_compile/T11141.hs - + testsuite/tests/typecheck/should_compile/T11141.stderr - + testsuite/tests/typecheck/should_compile/T11505Bar.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs-boot - + testsuite/tests/typecheck/should_compile/T12046.hs - testsuite/tests/typecheck/should_compile/T26225.hs - testsuite/tests/typecheck/should_compile/all.T - + testsuite/tests/typecheck/should_fail/T26823.hs - + testsuite/tests/typecheck/should_fail/T26823.stderr - testsuite/tests/typecheck/should_fail/all.T The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/eda74917d34ad015e2a0bc7b8d8426… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/eda74917d34ad015e2a0bc7b8d8426… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/dcoutts/posix-ticker] 6 commits: Note that rtsTimerSignal is deprecated.
by Duncan Coutts (＠dcoutts) 26 Mar '26

26 Mar '26

Duncan Coutts pushed to branch wip/dcoutts/posix-ticker at Glasgow Haskell Compiler / GHC Commits: b326559b by Duncan Coutts at 2026-03-25T09:35:19+00:00 Note that rtsTimerSignal is deprecated. - - - - - b9b13d71 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Add a rts posix FdWakup utility module 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 a thread is blocked on a set of fds anyway. It uses the classic self-pipe trick, or equivalently eventfd on supported platforms. This will initially be used to implement prompt interrupt or shutdown of the posix ticker thread. - - - - - f772e4fc by Duncan Coutts at 2026-03-25T09:42:50+00:00 Add prompt shutdown to the pthread ticker implementation. The Linux timerfd ticker monitors a pipe which is used by exitTicker to ensure a prompt wakeup and shutdown. The pthread ticker lacked this and so would only exit at the next ticker wakeup (10ms by default). This patch adds the same mechanism to the pthread ticker. This changes the pthread ticker from waiting by using nanosleep() to waiting using either ppoll() or select(), so that it can wait on both a time and a file descriptor. On Linux at least, a test program to compare the timing jitter of these APIs shows that using nanpsleep, ppoll or select makes no statistical difference to the maximum or average jitter. This is a step towards unifying the posix ticker implementations, so that we can have just one portable one (albeit with some limited cpp). It is also a step towards using the ticker as part of a more general implementation of wakeUpRts, since this will require a method to wake the rts from a signal handler context (ctl-c handler). - - - - - 961da708 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Update ticker header commentary It was antique and didn't apply even to the previous implementation, and certainly not to the updated one. - - - - - ed56824f by Duncan Coutts at 2026-03-25T09:42:50+00:00 Remove the timerfd-based ticker implementation There does not appear to be any remaining advantage on Linux to using the timerfd ticker implementation over the portable one (using ppoll on Linux for precise timing). The eventfd implementation was originally added at a time when Linux was still using a signal based implementation. So it made sense at the time. See (closed) issue #10840. - - - - - 31e49b58 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Consolidate to a single posix ticker implementation Previously we had four implementations, two using signals and two using threads. Having just one should make behaviour more consistent between platforms, and should make maintenance easier. - - - - - 7 changed files: - rts/include/rts/Timer.h - + rts/posix/FdWakeup.c - + rts/posix/FdWakeup.h - rts/posix/Ticker.c - − rts/posix/ticker/Pthread.c - − rts/posix/ticker/TimerFd.c - rts/rts.cabal Changes: ===================================== rts/include/rts/Timer.h ===================================== @@ -15,4 +15,4 @@ void startTimer (void); void stopTimer (void); -int rtsTimerSignal (void); +int rtsTimerSignal (void); // Deprecated: see issue #27073 ===================================== rts/posix/FdWakeup.c ===================================== @@ -0,0 +1,134 @@ +/* ----------------------------------------------------------------------------- + * + * (c) The GHC Team 2025 + * + * Utilities for a simple fd-based cross-thread wakeup mechanism. + * + * This is used to provide a mechanism to wake a thread when it is blocked + * waiting on fds and timeouts. The mechanism works by including the read end + * fd into the set of fds the thread waits on, and when a wake up is needed, + * the write end fd is used. + * + * This is implemented using either eventfd() or pipe(). + * + * Linux 2.6.22+ and FreeBSD 13+ support eventfd. It is a single fd with a + * 64bit counter. It uses less resources than a pipe, and is probably a tad + * faster. Using write() adds to the counter, while read() reads and resets + * it. This gives us event combining. + * + * Otherwise we use a classic unix pipe. + * + * -------------------------------------------------------------------------*/ + +#include "rts/PosixSource.h" +#include "Rts.h" + +#include "FdWakeup.h" + +#include <fcntl.h> +#include <unistd.h> + +#ifdef HAVE_SYS_EVENTFD_H +#include <sys/eventfd.h> +#endif + +#if !defined(HAVE_EVENTFD) \ + || (defined(HAVE_EVENTFD) && !(defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK))) +static void fcntl_CLOEXEC_NONBLOCK(int fd) +{ + int res1 = fcntl(fd, F_SETFD, FD_CLOEXEC); + int res2 = fcntl(fd, F_SETFL, O_NONBLOCK); + if (RTS_UNLIKELY(res1 < 0 || res2 < 0)) { + sysErrorBelch("newFdWakeup fcntl()"); + stg_exit(EXIT_FAILURE); + } +} +#endif + +void newFdWakeup(int *wakeup_fd_r, int *wakeup_fd_w) +{ +#if defined(HAVE_EVENTFD) + int wakeup_fd; +#if defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK) + wakeup_fd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK); +#else + wakeup_fd = eventfd(0, 0); + if (wakeup_fd >= 0) fcntl_CLOEXEC_NONBLOCK(wakeup_fd); +#endif + if (RTS_UNLIKELY(wakeup_fd < 0)) { + sysErrorBelch("newFdWakeup eventfd()"); + stg_exit(EXIT_FAILURE); + } + /* eventfd uses the same fd for each end */ + *wakeup_fd_r = wakeup_fd; + *wakeup_fd_w = wakeup_fd; +#else + int pipefd[2]; + int res; + res = pipe(pipefd); + if (RTS_UNLIKELY(res < 0)) { + sysErrorBelch("newFdWakeup pipe"); + stg_exit(EXIT_FAILURE); + } + fcntl_CLOEXEC_NONBLOCK(pipefd[0]); + fcntl_CLOEXEC_NONBLOCK(pipefd[1]); + *wakeup_fd_r = pipefd[0]; /* read end */ + *wakeup_fd_w = pipefd[1]; /* write end */ +#endif +} + +void closeFdWakeup(int wakeup_fd_r, int wakeup_fd_w) +{ +#if defined(HAVE_EVENTFD) + ASSERT(wakeup_fd_r == wakeup_fd_w); + close(wakeup_fd_r); +#else + ASSERT(wakeup_fd_r != wakeup_fd_w); + close(wakeup_fd_r); + close(wakeup_fd_w); +#endif +} + +/* This is safe to use from a signal handler. Using write() to a pipe + * or eventfd is fine. */ +void sendFdWakeup(int wakeup_fd_w) +{ + int res; +#if defined(HAVE_EVENTFD) + uint64_t val = 1; + res = write(wakeup_fd_w, &val, 8); +#else + unsigned char buf = 1; + res = write(wakeup_fd_w, &buf, 1); +#endif + if (RTS_UNLIKELY(res < 0)) { + /* Unlikely the pipe buffer will fill, but it would not be an error. */ + if (errno == EAGAIN) return; + sysErrorBelch("sendFdWakeup write"); + stg_exit(EXIT_FAILURE); + } +} + +void collectFdWakeup(int wakeup_fd_r) +{ + int res; +#if defined(HAVE_EVENTFD) + uint64_t buf; + /* eventfd combines events into one counter, so a single read is enough */ + res = read(wakeup_fd_r, &buf, 8); +#else + /* Drain the pipe buffer. Multiple wakeup notifications could + * have been sent before we have a chance to collect them. + */ + uint64_t buf; + do { + res = read(wakeup_fd_r, &buf, 8); + } while (res == 8); +#endif + if (RTS_UNLIKELY(res < 0)) { + /* After the first pipe read, it could block */ + if (errno == EAGAIN) return; + sysErrorBelch("collectFdWakeup read"); + stg_exit(EXIT_FAILURE); + } +} ===================================== rts/posix/FdWakeup.h ===================================== @@ -0,0 +1,40 @@ +/* ----------------------------------------------------------------------------- + * + * (c) The GHC Team 2025 + * + * Utilities for a simple fd-based cross-thread wakeup mechanism. + * + * It provides a mechanism for a thread that block on fds to add a simple + * wakeup/notification feature. + * + * Start with newFdWakeup, and pass the fd_r to the thread that needs the + * wakeup feature. The thread that needs to be woken should include the fd_r + * into the set of fds that the thread waits on (e.g. using poll or similar). + * If this fd becomes ready for read, the thread must call collectFdWakeup, + * and when a wake up is needed, the write end fd is used. In any other thread + * (or in a signal handler), call sendFdWakeup(fd_w) to (asynchronously) cause + * the wakeup. + * + * There is no message payload. Multiple wakeups may be combined (if they're + * sent multiple times before the notified thread can wake and call + * collectFdWakeup). + * + * The implementation uses pipe() or eventfd() on supported OSs. + * + * Prototypes for functions in FdWakeup.c + * + * -------------------------------------------------------------------------*/ + +#pragma once + +#include "BeginPrivate.h" + +void newFdWakeup(int *fd_r, int *fd_w); +void closeFdWakeup(int fd_r, int fd_w); + +/* This is safe to use from a signal handler */ +void sendFdWakeup(int fd_w); +void collectFdWakeup(int fd_r); + +#include "EndPrivate.h" + ===================================== rts/posix/Ticker.c ===================================== @@ -1,19 +1,53 @@ /* ----------------------------------------------------------------------------- * - * (c) The GHC Team, 1995-2007 + * (c) The GHC Team, 1995-2026 * - * Posix implementation(s) of the interval timer for profiling and pre-emptive - * scheduling. + * The posix implementation of the interval timer, used for pre-emptive + * scheduling of Haskell threads, and for sample based profiling. + * + * This file defines the "ticker": the platform-specific service to install and + * run the timer. See rts/Timer.c for the platform-dependent view of interval + * timing. * * ---------------------------------------------------------------------------*/ -/* The interval timer is used for profiling and for context switching. - * This file defines the platform-specific services to install and run the - * timers, and we call this the ticker. See rts/Timer.c for the - * platform-dependent view of interval timing. +/* This implementation uses a posix thread which repeatedly blocks on a timeout + * using either the ppoll() or select() API. This lets it also block on a file + * descriptor for early wakeup. + * + * The design uses a simple relative time delay with no catchup. That is, time + * spent by the ticker thread itself (e.g. flushing eventlog buffers) is not + * accounted for, and the next tick is delayed by that much (modulo wakeup + * jitter). This is probably the right thing to do: generally in realtime + * systems one does not want to try to catch up when behind, since that tends + * towards oversubscribing resources. Graceful degredation is usually + * preferable. + * + * Experimental results (on Linux 6.18 on x86-64) to measure the typical + * difference between the requested wakeup time and actual wakeup time for + * different delay intervals: + * + * interval typical actual wakeup time after due time + * 10000us 340 -- 400us (this is the default interval) + * 1000us 55 -- 100us + * 100us 55us + * 10us 55us + * + * While there's quite a bit of variance to these numbers, the results do not + * vary significantly between using select, ppoll or nanosleep. + * + * On Linux at least, for longer delays the kernel allows itself lower wakeup + * accuracy (which allows it to save power by coalescing multiple wakeups). + * Similarly, the reason for 55us on the low end is that the default thread + * timer slack on Linux is 50us, and context switch time accounts for the + * remainder. + * + * In conclusion, on Linux at least, the accuracy is fine, both for the + * default interval (10ms, 10000us) and for shorter intervals used during + * profiling. * * Historically we had ticker implementations using signals. This was always a - * rather shakey thing to do but we had few alternatives. + * rather shakey thing to do but we originally had few alternatives. * - One problem with using signals is that there are severe limits on what * code can be called from signal handlers. In particular it's not possible * to take locks in a signal handler contex. This was enough for contex @@ -23,17 +57,245 @@ * calls (#10840) or can be overwritten by user code. */ -/* Select a ticker implementation to use: - * - * On modern Linux, FreeBSD and NetBSD we can use timerfd_create and a thread - * that waits on it using poll. Linux has had timerfd since version 2.6.25. - * NetBSD has had timerfd since version 10, and FreeBSD since version 15. - * - * For older version of linux/bsd without timerfd, and for all other posix - * platforms, we use the implementation using posix pthreads and nanosleep(). +#include "rts/PosixSource.h" +#include "Rts.h" + +#include "Ticker.h" +#include "RtsUtils.h" +#include "Proftimer.h" +#include "Schedule.h" +#include "posix/Clock.h" +#include "posix/FdWakeup.h" + +#if defined(HAVE_DECL_PPOLL) && HAVE_DECL_PPOLL == 1 +/* We prefer the ppoll() function if available since it allows sanely waiting + * on a single fd with precise timeouts (nanosecond precision). It is not in + * the posix standard however and some platforms (notably glibc and freebsd) + * need special CPP defines to make it available: + */ +#define _GNU_SOURCE 1 +#define __BSD_VISIBLE 1 +#include <signal.h> +#include <poll.h> +#else +/* Otherwise we use the classic select(), which does have microsecond + * precision, but requires we build three whole 1024 bit (128 byte) fd sets + * just to wait on one fd. */ -#if defined(HAVE_SYS_TIMERFD_H) -#include "ticker/TimerFd.c" +#include <sys/select.h> +#endif + +#include <time.h> +#if HAVE_SYS_TIME_H +# include <sys/time.h> +#endif + +#if defined(HAVE_SIGNAL_H) +# include <signal.h> +#endif + +#include <string.h> + +#include <pthread.h> +#if defined(HAVE_PTHREAD_NP_H) +#include <pthread_np.h> +#endif +#include <unistd.h> +#include <fcntl.h> + +static Time itimer_interval = DEFAULT_TICK_INTERVAL; + +// Should we be firing ticks? +// Writers to this must hold the mutex below. +static bool stopped = false; + +// should the ticker thread exit? +// This can be set without holding the mutex. +static bool exited = true; + +// Signaled when we want to (re)start the timer +static Condition start_cond; +static Mutex mutex; +static OSThreadId thread; + +// fds for interrupting the ticker +static int interruptfd_r = -1, interruptfd_w = -1; + +static void *itimer_thread_func(void *_handle_tick) +{ + TickProc handle_tick = _handle_tick; + +#if defined(HAVE_DECL_PPOLL) && HAVE_DECL_PPOLL == 1 + struct pollfd pollfds[1]; + + pollfds[0].fd = interruptfd_r; + pollfds[0].events = POLLIN; + + struct timespec ts = { .tv_sec = TimeToSeconds(itimer_interval) + , .tv_nsec = TimeToNS(itimer_interval) % 1000000000 + }; #else -#include "ticker/Pthread.c" + fd_set selectfds; + FD_ZERO(&selectfds); + FD_SET(interruptfd_r, &selectfds); + + struct timeval tv = { .tv_sec = TimeToSeconds(itimer_interval) + /* convert remainder time in nanoseconds + to microseconds, rounding up: */ + , .tv_usec = ((TimeToNS(itimer_interval) % 1000000000) + + 999) / 1000 + }; +#endif + + // Relaxed is sufficient: If we don't see that exited was set in one iteration we will + // see it next time. + while (!RELAXED_LOAD_ALWAYS(&exited)) { + +#if defined(HAVE_DECL_PPOLL) && HAVE_DECL_PPOLL == 1 + int nfds = 1; + int nready = ppoll(pollfds, nfds, &ts, NULL); +#else + struct timeval tv_tmp = tv; // copy since select may change this value. + int nfds = interruptfd_r+1; + int nready = select(nfds, &selectfds, NULL, NULL, &tv_tmp); +#endif + // In either case (ppoll or select), the result nready is the number + // of fds that are ready. + if (RTS_LIKELY(nready == 0)) { + // Timer expired, not interrupted, continue. + } else if (nready > 0) { + // We only monitor one fd (the interruptfd_r), so we know + // it is that fd that is ready without any further checks. + collectFdWakeup(interruptfd_r); + // No further action needed, continue on to handling the final tick + // and then stop. + + // Note that we rely on sendFdWakeup and select/poll to provide the + // happens-before relation. So if 'exited' was set before calling + // sendFdWakeup, then we should be able to reliably read it after. + // And thus reading 'exited' in the while loop guard is ok. + } else { + // While the RTS attempts to mask signals, some foreign libraries + // that rely on signal delivery may unmask them. Consequently we + // may see EINTR. See #24610. + if (errno != EINTR) { + sysErrorBelch("Ticker: poll failed: %s", strerror(errno)); + } + } + + // first try a cheap test + if (RELAXED_LOAD_ALWAYS(&stopped)) { + OS_ACQUIRE_LOCK(&mutex); + // should we really stop? + if (stopped) { + waitCondition(&start_cond, &mutex); + } + OS_RELEASE_LOCK(&mutex); + } else { + handle_tick(0); + } + } + + return NULL; +} + +void +initTicker (Time interval, TickProc handle_tick) +{ + itimer_interval = interval; + stopped = true; + exited = false; +#if defined(HAVE_SIGNAL_H) + sigset_t mask, omask; + int sigret; +#endif + int ret; + + initCondition(&start_cond); + initMutex(&mutex); + + /* Open the interrupt fd synchronously. + * + * We used to do it in itimer_thread_func (i.e. in the timer thread) but it + * meant that some user code could run before it and get confused by the + * allocation of the timerfd. + * + * See hClose002 which unsafely closes a file descriptor twice expecting an + * exception the second time: it sometimes failed when the second call to + * "close" closed our own timerfd which inadvertently reused the same file + * descriptor closed by the first call! (see #20618) + */ + + if (interruptfd_r != -1) { + // don't leak the old file descriptors after a fork (#25280) + closeFdWakeup(interruptfd_r, interruptfd_w); + } + newFdWakeup(&interruptfd_r, &interruptfd_w); + + /* + * Create the thread with all blockable signals blocked, leaving signal + * handling to the main and/or other threads. This is especially useful in + * the non-threaded runtime, where applications might expect sigprocmask(2) + * to effectively block signals. + */ +#if defined(HAVE_SIGNAL_H) + sigfillset(&mask); + sigret = pthread_sigmask(SIG_SETMASK, &mask, &omask); +#endif + ret = createAttachedOSThread(&thread, "ghc_ticker", itimer_thread_func, (void*)handle_tick); +#if defined(HAVE_SIGNAL_H) + if (sigret == 0) + pthread_sigmask(SIG_SETMASK, &omask, NULL); #endif + + if (ret != 0) { + barf("Ticker: Failed to spawn thread: %s", strerror(errno)); + } +} + +void +startTicker(void) +{ + OS_ACQUIRE_LOCK(&mutex); + RELAXED_STORE(&stopped, false); + signalCondition(&start_cond); + OS_RELEASE_LOCK(&mutex); +} + +/* There may be at most one additional tick fired after a call to this */ +void +stopTicker(void) +{ + OS_ACQUIRE_LOCK(&mutex); + RELAXED_STORE(&stopped, true); + OS_RELEASE_LOCK(&mutex); +} + +/* There may be at most one additional tick fired after a call to this */ +void +exitTicker (bool wait) +{ + ASSERT(!SEQ_CST_LOAD(&exited)); + SEQ_CST_STORE(&exited, true); + // ensure that ticker wakes up if stopped + startTicker(); + sendFdWakeup(interruptfd_w); + + // wait for ticker to terminate if necessary + if (wait) { + if (pthread_join(thread, NULL)) { + sysErrorBelch("Ticker: Failed to join: %s", strerror(errno)); + } + closeFdWakeup(interruptfd_r, interruptfd_w); + closeMutex(&mutex); + closeCondition(&start_cond); + } else { + pthread_detach(thread); + } +} + +int +rtsTimerSignal(void) +{ + return SIGALRM; +} ===================================== rts/posix/ticker/Pthread.c deleted ===================================== @@ -1,195 +0,0 @@ -/* ----------------------------------------------------------------------------- - * - * (c) The GHC Team, 1995-2007 - * - * Interval timer for profiling and pre-emptive scheduling. - * - * ---------------------------------------------------------------------------*/ - -/* - * We use a realtime timer by default. I found this much more - * reliable than a CPU timer: - * - * Experiments with different frequencies: using - * CLOCK_REALTIME/CLOCK_MONOTONIC on Linux 2.6.32, - * 1000us has <1% impact on runtime - * 100us has ~2% impact on runtime - * 10us has ~40% impact on runtime - * - * using CLOCK_PROCESS_CPUTIME_ID on Linux 2.6.32, - * I cannot get it to tick faster than 10ms (10000us) - * which isn't great for profiling. - * - * In the threaded RTS, we can't tick in CPU time because the thread - * which has the virtual timer might be idle, so the tick would never - * fire. Therefore we used to tick in realtime in the threaded RTS and - * in CPU time otherwise, but now we always tick in realtime, for - * several reasons: - * - * - resolution (see above) - * - consistency (-threaded is the same as normal) - * - more consistency: Windows only has a realtime timer - * - * Note we want to use CLOCK_MONOTONIC rather than CLOCK_REALTIME, - * because the latter may jump around (NTP adjustments, leap seconds - * etc.). - */ - -#include "rts/PosixSource.h" -#include "Rts.h" - -#include "Ticker.h" -#include "RtsUtils.h" -#include "Proftimer.h" -#include "Schedule.h" -#include "posix/Clock.h" -#include <poll.h> - -#include <time.h> -#if HAVE_SYS_TIME_H -# include <sys/time.h> -#endif - -#if defined(HAVE_SIGNAL_H) -# include <signal.h> -#endif - -#include <string.h> - -#include <pthread.h> -#if defined(HAVE_PTHREAD_NP_H) -#include <pthread_np.h> -#endif -#include <unistd.h> -#include <fcntl.h> - -/* - * TFD_CLOEXEC has been added in Linux 2.6.26. - * If it is not available, we use fcntl(F_SETFD). - */ -#if !defined(TFD_CLOEXEC) -#define TFD_CLOEXEC 0 -#endif - -static Time itimer_interval = DEFAULT_TICK_INTERVAL; - -// Should we be firing ticks? -// Writers to this must hold the mutex below. -static bool stopped = false; - -// should the ticker thread exit? -// This can be set without holding the mutex. -static bool exited = true; - -// Signaled when we want to (re)start the timer -static Condition start_cond; -static Mutex mutex; -static OSThreadId thread; - -static void *itimer_thread_func(void *_handle_tick) -{ - TickProc handle_tick = _handle_tick; - - // Relaxed is sufficient: If we don't see that exited was set in one iteration we will - // see it next time. - while (!RELAXED_LOAD_ALWAYS(&exited)) { - if (rtsSleep(itimer_interval) != 0) { - sysErrorBelch("Ticker: sleep failed: %s", strerror(errno)); - } - - // first try a cheap test - if (RELAXED_LOAD_ALWAYS(&stopped)) { - OS_ACQUIRE_LOCK(&mutex); - // should we really stop? - if (stopped) { - waitCondition(&start_cond, &mutex); - } - OS_RELEASE_LOCK(&mutex); - } else { - handle_tick(0); - } - } - - return NULL; -} - -void -initTicker (Time interval, TickProc handle_tick) -{ - itimer_interval = interval; - stopped = true; - exited = false; -#if defined(HAVE_SIGNAL_H) - sigset_t mask, omask; - int sigret; -#endif - int ret; - - initCondition(&start_cond); - initMutex(&mutex); - - /* - * Create the thread with all blockable signals blocked, leaving signal - * handling to the main and/or other threads. This is especially useful in - * the non-threaded runtime, where applications might expect sigprocmask(2) - * to effectively block signals. - */ -#if defined(HAVE_SIGNAL_H) - sigfillset(&mask); - sigret = pthread_sigmask(SIG_SETMASK, &mask, &omask); -#endif - ret = createAttachedOSThread(&thread, "ghc_ticker", itimer_thread_func, (void*)handle_tick); -#if defined(HAVE_SIGNAL_H) - if (sigret == 0) - pthread_sigmask(SIG_SETMASK, &omask, NULL); -#endif - - if (ret != 0) { - barf("Ticker: Failed to spawn thread: %s", strerror(errno)); - } -} - -void -startTicker(void) -{ - OS_ACQUIRE_LOCK(&mutex); - RELAXED_STORE(&stopped, false); - signalCondition(&start_cond); - OS_RELEASE_LOCK(&mutex); -} - -/* There may be at most one additional tick fired after a call to this */ -void -stopTicker(void) -{ - OS_ACQUIRE_LOCK(&mutex); - RELAXED_STORE(&stopped, true); - OS_RELEASE_LOCK(&mutex); -} - -/* There may be at most one additional tick fired after a call to this */ -void -exitTicker (bool wait) -{ - ASSERT(!SEQ_CST_LOAD(&exited)); - SEQ_CST_STORE(&exited, true); - // ensure that ticker wakes up if stopped - startTicker(); - - // wait for ticker to terminate if necessary - if (wait) { - if (pthread_join(thread, NULL)) { - sysErrorBelch("Ticker: Failed to join: %s", strerror(errno)); - } - closeMutex(&mutex); - closeCondition(&start_cond); - } else { - pthread_detach(thread); - } -} - -int -rtsTimerSignal(void) -{ - return SIGALRM; -} ===================================== rts/posix/ticker/TimerFd.c deleted ===================================== @@ -1,291 +0,0 @@ -/* ----------------------------------------------------------------------------- - * - * (c) The GHC Team, 1995-2023 - * - * Interval timer for profiling and pre-emptive scheduling. - * - * ---------------------------------------------------------------------------*/ - -/* - * We use a realtime timer by default. I found this much more - * reliable than a CPU timer: - * - * Experiments with different frequencies: using - * CLOCK_REALTIME/CLOCK_MONOTONIC on Linux 2.6.32, - * 1000us has <1% impact on runtime - * 100us has ~2% impact on runtime - * 10us has ~40% impact on runtime - * - * using CLOCK_PROCESS_CPUTIME_ID on Linux 2.6.32, - * I cannot get it to tick faster than 10ms (10000us) - * which isn't great for profiling. - * - * In the threaded RTS, we can't tick in CPU time because the thread - * which has the virtual timer might be idle, so the tick would never - * fire. Therefore we used to tick in realtime in the threaded RTS and - * in CPU time otherwise, but now we always tick in realtime, for - * several reasons: - * - * - resolution (see above) - * - consistency (-threaded is the same as normal) - * - more consistency: Windows only has a realtime timer - * - * Note we want to use CLOCK_MONOTONIC rather than CLOCK_REALTIME, - * because the latter may jump around (NTP adjustments, leap seconds - * etc.). - */ - -#include "rts/PosixSource.h" -#include "Rts.h" - -#include "Ticker.h" -#include "RtsUtils.h" -#include "Proftimer.h" -#include "Schedule.h" -#include "posix/Clock.h" -#include <poll.h> - -#include <time.h> -#if HAVE_SYS_TIME_H -# include <sys/time.h> -#endif - -#if defined(HAVE_SIGNAL_H) -# include <signal.h> -#endif - -#include <string.h> - -#include <pthread.h> -#if defined(HAVE_PTHREAD_NP_H) -#include <pthread_np.h> -#endif -#include <unistd.h> -#include <fcntl.h> - -#include <sys/timerfd.h> - - -/* - * TFD_CLOEXEC has been added in Linux 2.6.26. - * If it is not available, we use fcntl(F_SETFD). - */ -#if !defined(TFD_CLOEXEC) -#define TFD_CLOEXEC 0 -#endif - -static Time itimer_interval = DEFAULT_TICK_INTERVAL; - -// Should we be firing ticks? -// Writers to this must hold the mutex below. -static bool stopped = false; - -// should the ticker thread exit? -// This can be set without holding the mutex. -static bool exited = true; - -// Signaled when we want to (re)start the timer -static Condition start_cond; -static Mutex mutex; -static OSThreadId thread; - -// file descriptor for the timer (Linux only) -static int timerfd = -1; - -// pipe for signaling exit -static int pipefds[2]; - -static void *itimer_thread_func(void *_handle_tick) -{ - TickProc handle_tick = _handle_tick; - uint64_t nticks; - ssize_t r = 0; - struct pollfd pollfds[2]; - - pollfds[0].fd = pipefds[0]; - pollfds[0].events = POLLIN; - pollfds[1].fd = timerfd; - pollfds[1].events = POLLIN; - - // Relaxed is sufficient: If we don't see that exited was set in one iteration we will - // see it next time. - while (!RELAXED_LOAD_ALWAYS(&exited)) { - if (poll(pollfds, 2, -1) == -1) { - // While the RTS attempts to mask signals, some foreign libraries - // may rely on signal delivery may unmask them. Consequently we may - // see EINTR. See #24610. - if (errno != EINTR) { - sysErrorBelch("Ticker: poll failed: %s", strerror(errno)); - } - } - - // We check the pipe first, even though the timerfd may also have triggered. - if (pollfds[0].revents & POLLIN) { - // the pipe is ready for reading, the only possible reason is that we're exiting - exited = true; // set this again to make sure even RELAXED_LOAD will read the proper value - // no further action needed, skip ahead to handling the final tick and then stopping - } - else if (pollfds[1].revents & POLLIN) { // the timerfd is ready for reading - r = read(timerfd, &nticks, sizeof(nticks)); // this should never block now - - if ((r == 0) && (errno == 0)) { - /* r == 0 is expected only for non-blocking fd (in which case - * errno should be EAGAIN) but we use a blocking fd. - * - * Due to a kernel bug (cf https://lkml.org/lkml/2019/8/16/335) - * on some platforms we could see r == 0 and errno == 0. - */ - IF_DEBUG(scheduler, debugBelch("read(timerfd) returned 0 with errno=0. This is a known kernel bug. We just ignore it.")); - } - else if (r != sizeof(nticks) && errno != EINTR) { - barf("Ticker: read(timerfd) failed with %s and returned %zd", strerror(errno), r); - } - } - - // first try a cheap test - if (RELAXED_LOAD_ALWAYS(&stopped)) { - OS_ACQUIRE_LOCK(&mutex); - // should we really stop? - if (stopped) { - waitCondition(&start_cond, &mutex); - } - OS_RELEASE_LOCK(&mutex); - } else { - handle_tick(0); - } - } - - close(timerfd); - return NULL; -} - -void -initTicker (Time interval, TickProc handle_tick) -{ - itimer_interval = interval; - stopped = true; - exited = false; -#if defined(HAVE_SIGNAL_H) - sigset_t mask, omask; - int sigret; -#endif - int ret; - - initCondition(&start_cond); - initMutex(&mutex); - - /* Open the file descriptor for the timer synchronously. - * - * We used to do it in itimer_thread_func (i.e. in the timer thread) but it - * meant that some user code could run before it and get confused by the - * allocation of the timerfd. - * - * See hClose002 which unsafely closes a file descriptor twice expecting an - * exception the second time: it sometimes failed when the second call to - * "close" closed our own timerfd which inadvertently reused the same file - * descriptor closed by the first call! (see #20618) - */ - struct itimerspec it; - it.it_value.tv_sec = TimeToSeconds(itimer_interval); - it.it_value.tv_nsec = TimeToNS(itimer_interval) % 1000000000; - it.it_interval = it.it_value; - - if (timerfd != -1) { - // don't leak the old file descriptors after a fork (#25280) - close(timerfd); - close(pipefds[0]); - close(pipefds[1]); - timerfd = -1; - } - - timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC); - if (timerfd == -1) { - barf("timerfd_create: %s", strerror(errno)); - } - if (!TFD_CLOEXEC) { - fcntl(timerfd, F_SETFD, FD_CLOEXEC); - } - if (timerfd_settime(timerfd, 0, &it, NULL)) { - barf("timerfd_settime: %s", strerror(errno)); - } - - if (pipe(pipefds) < 0) { - barf("pipe: %s", strerror(errno)); - } - - /* - * Create the thread with all blockable signals blocked, leaving signal - * handling to the main and/or other threads. This is especially useful in - * the non-threaded runtime, where applications might expect sigprocmask(2) - * to effectively block signals. - */ -#if defined(HAVE_SIGNAL_H) - sigfillset(&mask); - sigret = pthread_sigmask(SIG_SETMASK, &mask, &omask); -#endif - ret = createAttachedOSThread(&thread, "ghc_ticker", itimer_thread_func, (void*)handle_tick); -#if defined(HAVE_SIGNAL_H) - if (sigret == 0) - pthread_sigmask(SIG_SETMASK, &omask, NULL); -#endif - - if (ret != 0) { - barf("Ticker: Failed to spawn thread: %s", strerror(errno)); - } -} - -void -startTicker(void) -{ - OS_ACQUIRE_LOCK(&mutex); - RELAXED_STORE(&stopped, false); - signalCondition(&start_cond); - OS_RELEASE_LOCK(&mutex); -} - -/* There may be at most one additional tick fired after a call to this */ -void -stopTicker(void) -{ - OS_ACQUIRE_LOCK(&mutex); - RELAXED_STORE(&stopped, true); - OS_RELEASE_LOCK(&mutex); -} - -/* There may be at most one additional tick fired after a call to this */ -void -exitTicker (bool wait) -{ - ASSERT(!SEQ_CST_LOAD(&exited)); - SEQ_CST_STORE(&exited, true); - // ensure that ticker wakes up if stopped - startTicker(); - - // wait for ticker to terminate if necessary - if (wait) { - // write anything to the pipe to trigger poll() in the ticker thread - if (write(pipefds[1], "stop", 5) < 0) { - sysErrorBelch("Ticker: Failed to write to pipe: %s", strerror(errno)); - } - - if (pthread_join(thread, NULL)) { - sysErrorBelch("Ticker: Failed to join: %s", strerror(errno)); - } - - // These need to happen AFTER the ticker thread has finished to prevent a race condition - // where the ticker thread closes the read end of the pipe before we're done writing to it. - close(pipefds[0]); - close(pipefds[1]); - - closeMutex(&mutex); - closeCondition(&start_cond); - } else { - pthread_detach(thread); - } -} - -int -rtsTimerSignal(void) -{ - return SIGALRM; -} ===================================== rts/rts.cabal ===================================== @@ -582,11 +582,9 @@ library posix/Ticker.c posix/OSMem.c posix/OSThreads.c + posix/FdWakeup.c posix/Poll.c posix/Select.c posix/Signals.c posix/Timeout.c posix/TTY.c - -- ticker/*.c - -- We don't want to compile posix/ticker/*.c, these will be #included - -- from Ticker.c View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b1d18cd217f4384dd8b06350c1b5ef… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b1d18cd217f4384dd8b06350c1b5ef… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/dcoutts/idle-gc] 39 commits: ghci: Mention active language edition in startup banner
by Duncan Coutts (＠dcoutts) 26 Mar '26

26 Mar '26

Duncan Coutts pushed to branch wip/dcoutts/idle-gc at Glasgow Haskell Compiler / GHC Commits: e34cb6da by Adam Gundry at 2026-03-20T12:20:00-04:00 ghci: Mention active language edition in startup banner Per GHC proposal 632, this makes the GHCi startup banner include the active language edition, plus an indication of whether this was the default (as opposed to being explicitly selected via an option such as `-XGHC2024`). For example: ``` $ ghci GHCi, version 9.14.1: https://www.haskell.org/ghc/ :? for help Using default language edition: GHC2024 ghci> ``` Fixes #26037. - - - - - 52c3e6ba by sheaf at 2026-03-20T12:21:09-04:00 Improve incomplete record selector warnings This commit stops GHC from emitting spurious incomplete record selector warnings for bare selectors/projections such as .fld There are two places we currently emit incomplete record selector warnings: 1. In the desugarer, when we see a record selector or an occurrence of 'getField'. Here, we can use pattern matching information to ensure we don't give false positives. 2. In the typechecker, which might sometimes give false positives but can emit warnings in cases that the pattern match checker would otherwise miss. This is explained in Note [Detecting incomplete record selectors] in GHC.HsToCore.Pmc. Now, we obviously don't want to emit the same error twice, and generally we prefer (1), as those messages contain fewer false positives. So we suppress (2) when we are sure we are going to emit (1); the logic for doing so is in GHC.Tc.Instance.Class.warnIncompleteRecSel, and works by looking at the CtOrigin. Now, the issue was that this logic handled explicit record selectors as well as overloaded record field selectors such as "x.r" (which turns into a simple GetFieldOrigin CtOrigin), but it didn't properly handle record projectors like ".fld" or ".fld1.fld2" (which result in other CtOrigins such as 'RecordFieldProjectionOrigin'). To solve this problem, we re-use the 'isHasFieldOrigin' introduced in fbdc623a (slightly adjusted). On the way, we also had to update the desugarer with special handling for the 'ExpandedThingTc' case in 'ds_app', to make sure that 'ds_app_var' sees all the type arguments to 'getField' in order for it to indeed emit warnings like in (1). Fixes #26686 - - - - - 309d7e87 by Cheng Shao at 2026-03-20T12:21:53-04:00 rts: opportunistically grow the MutableByteArray# in-place in resizeMutableByteArray# Following !15234, this patch improves `resizeMutableByteArray#` memory efficiency by growing the `MutableByteArray#` in-place if possible, addressing an old todo comment here. Also adds a new test case `resizeMutableByteArrayInPlace` that stresses this behavior. - - - - - 7d4ef162 by Matthew Craven at 2026-03-20T12:22:47-04:00 Change representation of floating point literals This commit changes the representation of floating point literals throughough the compiler, in particular in Core and Cmm. The Rational type is deficient for this purpose, dealing poorly with NaN, +/-Infinity, and negative zero. Instead, the new module GHC.Types.Literal.Floating uses the host Float/Double type to represent NaNs, infinities and negative zero. It also contains a Rational constructor, for the benefit of -fexcess-precision. Other changes: - Remove Note [negative zero] and related code This also removes the restrictions on constant-folding of division by zero, and should make any problems with NaN/Infinity more obvious. - Use -0.0 as the additive identity for Core constant folding rules for floating-point addition, fixing #21227. - Manual worker-wrapper for GHC.Float.rationalToDouble. This is intended to prevent the compiler's WW on this function from interfering with constant-folding. This change means that we now avoid allocating a box for the result of a 'realToFrac' call in T10359. - Combine floatDecodeOp and doubleDecodeOp. This change also fixes a bug in doubleDecodeOp wherein it would incorrectly produce an Int# instead of an Int64# literal for the mantissa component with 64-bit targets. - Use Float/Double for assembly immediates, and update the X86 and PowerPC backends to properly handle special values such as NaN and infinity. - Allow 'rational_to' to handle zero denominators, fixing a TODO in GHC.Core.Opt.ConstantFold. Fixes #8364 #9811 #18897 #21227 Progress towards #26919 Metric Decrease: T10359 Co-authored-by: sheaf <sam.derbyshire(a)gmail.com> ------------------------- Metric Decrease: T1969 T5321FD ------------------------- - - - - - 80e2dd4f by Zubin Duggal at 2026-03-20T12:23:33-04:00 compiler/ffi: Collapse void pointer chains in capi wrappers New gcc/clang treat -Wincompatible-pointer-types as an error by default. Since C only allows implicit conversion from void*, not void**, capi wrappers for functions taking e.g. abstract** would fail to compile when the Haskell type Ptr (Ptr Abstract) was naively translated to void**. Collapse nested void pointers to a single void* when the pointee type has no known C representation. Fixes #26852 - - - - - 1c50bd7b by Luite Stegeman at 2026-03-20T12:24:37-04:00 Move some functions related to pointer tagging to a separate module - - - - - bfd7aafd by Luite Stegeman at 2026-03-20T12:24:37-04:00 Branchless unpacking for enumeration types Change unpacking for enumeration types to go to Word8#/Word16#/Word# directly instead of going through an intermediate unboxed sum. This allows us to do a branchless conversion using DataToTag and TagToEnum. Fixes #26970 - - - - - 72b20fc0 by Luite Stegeman at 2026-03-20T12:25:30-04:00 bytecode: Carefully SLIDE off the end of a stack chunk The SLIDE bytecode instruction was not checking for stack chunk boundaries and could corrupt the stack underflow frame, leading to crashes. We add a check to use safe writes if we cross the chunk boundary and also handle stack underflow if Sp is advanced past the underflow frame. fix #27001 - - - - - 2e22b43c by Cheng Shao at 2026-03-20T12:26:14-04:00 ghci: serialize BCOByteArray buffer directly when possible This patch changes the `Binary` instances of `BCOByteArray` to directly serialize the underlying buffer when possible, while also taking into account the issue of host-dependent `Word` width. See added comments and amended `Note [BCOByteArray serialization]` for detailed explanation. Closes #27020. - - - - - 89d9ba37 by Sylvain Henry at 2026-03-20T12:27:34-04:00 JS: replace BigInt with Number arithmetic for 32/64-bit quot/rem (#23597) Replace BigInt-based implementations of quotWord32, remWord32, quotRemWord32, quotRem2Word32, quotWord64, remWord64, quotInt64, and remInt64 with pure Number (double/integer) arithmetic to avoid the overhead of BigInt promotion. - - - - - ae4ddd60 by Sylvain Henry at 2026-03-20T12:28:28-04:00 Core: add constant-folding rules for Addr# eq/ne (#18032) - - - - - 3e767f98 by Matthew Pickering at 2026-03-20T12:29:11-04:00 Use OsPath rather than FilePath in Downsweep cache This gets us one step closure to uniformly using `OsPath` in the compiler. - - - - - 2c57de29 by Cheng Shao at 2026-03-20T12:29:55-04:00 hadrian: fix ghc-in-ghci flavour stage0 shared libraries This patch fixes missing stage0 shared libraries in hadrian ghc-in-ghci flavour, which was accidentally dropped in 669d09f950a6e88b903d9fd8a7571531774d4d5d and resulted in a regression in HLS support on linux/macos. Fixes #27057. - - - - - 5b1be555 by Sylvain Henry at 2026-03-20T12:30:48-04:00 JS: install rts/Types.h header file (#27033) It was an omission, making HsFFI.h not usable with GHC using the JS backend. - - - - - b883f08f by Cheng Shao at 2026-03-20T12:31:33-04:00 hadrian: don't compile RTS with -Winline This patch removes `-Winline` from cflags when compiling the RTS, given that: 1. It generates a huge pile of spam and hurts developer experience 2. Whether inlining happens is highly dependent on toolchains, flavours, etc, and it's not really an issue to fix if inlining doesn't happen; it's a hint to the C compiler anyway. Fixes #27060. - - - - - 333387d6 by Cheng Shao at 2026-03-20T12:31:33-04:00 hadrian: compile libffi-clib with -Wno-deprecated-declarations This patch adds `-Wno-deprecated-declarations` to cflags of `libffi-clib`, given that it produces noise at compile-time that aren't really our issue to fix anyway, it's from vendored libffi source code. - - - - - 67c47771 by Rodrigo Mesquita at 2026-03-20T12:32:17-04:00 Expose decodeStackWithIpe from ghc-experimental This decoding is useful to the debugger and it wasn't originally exported as an oversight. - - - - - 18513365 by Matthew Pickering at 2026-03-21T04:43:26-04:00 Add support for custom external interpreter commands It can be useful for GHC API clients to implement their own external interpreter commands. For example, the debugger may want an efficient way to inspect the stacks of the running threads in the external interpreter. - - - - - 4636d906 by mangoiv at 2026-03-21T04:44:10-04:00 ci: remove obsolete fallback for old debian and ubuntu versions - - - - - 2e3a2805 by mangoiv at 2026-03-21T04:44:10-04:00 ci: drop ubuntu 18 and 20 Ubuntu 18 EOL: May 2023 Ubuntu 20 EOL: May 2025 We should probably not make another major release supporting these platforms. Also updates the generator script. Resolves #25876 - - - - - de54e264 by Cheng Shao at 2026-03-21T17:52:08+01:00 rts: fix -Wcompare-distinct-pointer-types errors This commit fixes `-Wcompare-distinct-pointer-types` errors in the RTS which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. - - - - - b9bd73de by Cheng Shao at 2026-03-21T17:52:08+01:00 ghc-internal: fix unused imports This commit fixes unused imports in `ghc-internal` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #26987 #27059. - - - - - da946a16 by Cheng Shao at 2026-03-21T17:03:51+00:00 ghci: fix unused imports This commit fixes unused imports in `ghci` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #26987 #27059. - - - - - 955b1cf8 by Cheng Shao at 2026-03-21T17:03:51+00:00 compiler: fix unused imports in GHC.Tc.Types.Origin This commit fixes unused imports in `GHC.Tc.Types.Origin` which should have been caught by the `validate` flavour but was warnings in CI due to the recent `+werror` regression. Fixes #27059. - - - - - 3b1aeb50 by Cheng Shao at 2026-03-21T17:03:51+00:00 hadrian: fix missing +werror in validate flavour This patch fixes missing `+werror` in validate flavour, which was an oversight in bb3a2ba1eefadf0b2ef4f39b31337a23eec67f29. Fixes #27066. - - - - - 44f118f0 by Cheng Shao at 2026-03-22T04:54:01-04:00 ci: bump CACHE_REV and add the missing reminder This patch bumps `CACHE_REV` to address recent `[Cabal-7159]` CI errors due to stale cabal cache on some runners, and also adds a reminder to remind future maintainers. Fixes #27075. - - - - - 2a218737 by ARATA Mizuki at 2026-03-23T11:11:39-04:00 Add 128-bit SIMD support to AArch64 NCG Changes: - Add `Format` field to vector-capable instructions. These instructions will emit `vN.4s` (for example) as a operand. - Additional constructors for `Operand`: `OpVecLane` represents a vector lane and will be emitted as `vN.<width>[<index>]` (`vN.s[3]` for example). `OpScalarAsVec` represents a scalar, but printed as a vector lane like `vN.<width>[0]` (`vN.s[0]` for example). - Integer quot/rem are implemented in C, like x86. Closes #26536 Metric Increase: T3294 - - - - - 5d6e2be9 by ARATA Mizuki at 2026-03-23T11:11:39-04:00 AArch64 NCG: Improve code generation for floating-point and vector constants Some floating-point constants can be directly encoded using the FMOV instruction. Similarly, a class of vectors with same values can be encoded using FMOV, MOVI, or MVNI. - - - - - c6d262aa by Simon Jakobi at 2026-03-23T11:12:22-04:00 Add regression test for #13729 Closes #13729. - - - - - ae60a690 by Duncan Coutts at 2026-03-24T22:03:34+00:00 Remove signal-based ticker implementations Fixes issue #27073 All supported platforms should work with the pthreads + nanosleep based ticker implementation. This avoids all the problems with using signals. In practice, all supported platforms were probably using the non-signal tickers already, which is probably why we do not get lots of reports about deadlocks and other weirdness: we were definately using functions that are not async signal safe in the tick handler (such as fflush to flussh the eventlog). Only Solaris was explicitly using the timer_create ticker impl, and even Solaris could probably use the pthreads one (if anyone cared: Solaris is no longer a Teir 3 supported platform). Plausibly the only supported platform that this will change will be AIX, which should now use the pthreads impl. - - - - - a0c4271d by Duncan Coutts at 2026-03-24T22:03:34+00:00 Tidy up some timer/ticker comments elsewhere - - - - - c1ad27cf by Duncan Coutts at 2026-03-24T22:03:34+00:00 Remove now-unused install_vtalrm_handler Support function used by both of the signal-based ticker implementations. - - - - - d73c9bca by Duncan Coutts at 2026-03-24T22:03:34+00:00 No longer probe for timer_create in rts/configure It was only used by the TimerCreate.c ticker impl. - - - - - b326559b by Duncan Coutts at 2026-03-25T09:35:19+00:00 Note that rtsTimerSignal is deprecated. - - - - - b9b13d71 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Add a rts posix FdWakup utility module 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 a thread is blocked on a set of fds anyway. It uses the classic self-pipe trick, or equivalently eventfd on supported platforms. This will initially be used to implement prompt interrupt or shutdown of the posix ticker thread. - - - - - f772e4fc by Duncan Coutts at 2026-03-25T09:42:50+00:00 Add prompt shutdown to the pthread ticker implementation. The Linux timerfd ticker monitors a pipe which is used by exitTicker to ensure a prompt wakeup and shutdown. The pthread ticker lacked this and so would only exit at the next ticker wakeup (10ms by default). This patch adds the same mechanism to the pthread ticker. This changes the pthread ticker from waiting by using nanosleep() to waiting using either ppoll() or select(), so that it can wait on both a time and a file descriptor. On Linux at least, a test program to compare the timing jitter of these APIs shows that using nanpsleep, ppoll or select makes no statistical difference to the maximum or average jitter. This is a step towards unifying the posix ticker implementations, so that we can have just one portable one (albeit with some limited cpp). It is also a step towards using the ticker as part of a more general implementation of wakeUpRts, since this will require a method to wake the rts from a signal handler context (ctl-c handler). - - - - - 961da708 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Update ticker header commentary It was antique and didn't apply even to the previous implementation, and certainly not to the updated one. - - - - - ed56824f by Duncan Coutts at 2026-03-25T09:42:50+00:00 Remove the timerfd-based ticker implementation There does not appear to be any remaining advantage on Linux to using the timerfd ticker implementation over the portable one (using ppoll on Linux for precise timing). The eventfd implementation was originally added at a time when Linux was still using a signal based implementation. So it made sense at the time. See (closed) issue #10840. - - - - - 31e49b58 by Duncan Coutts at 2026-03-25T09:42:50+00:00 Consolidate to a single posix ticker implementation Previously we had four implementations, two using signals and two using threads. Having just one should make behaviour more consistent between platforms, and should make maintenance easier. - - - - - 174 changed files: - .gitlab-ci.yml - .gitlab/generate-ci/flake.lock - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - .gitlab/rel_eng/fetch-gitlab-artifacts/fetch_gitlab.py - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/CodeGen.Platform.h - compiler/GHC/Builtin/Names.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/Cmm/CommonBlockElim.hs - compiler/GHC/Cmm/Expr.hs - compiler/GHC/Cmm/Opt.hs - compiler/GHC/Cmm/Parser.y - compiler/GHC/Cmm/Type.hs - compiler/GHC/Cmm/Utils.hs - compiler/GHC/CmmToAsm/AArch64/CodeGen.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/AArch64/Ppr.hs - compiler/GHC/CmmToAsm/AArch64/Regs.hs - compiler/GHC/CmmToAsm/LA64/CodeGen.hs - compiler/GHC/CmmToAsm/LA64/Ppr.hs - compiler/GHC/CmmToAsm/LA64/Regs.hs - compiler/GHC/CmmToAsm/PPC/CodeGen.hs - compiler/GHC/CmmToAsm/PPC/Ppr.hs - compiler/GHC/CmmToAsm/PPC/Regs.hs - compiler/GHC/CmmToAsm/RV64/CodeGen.hs - compiler/GHC/CmmToAsm/RV64/Ppr.hs - compiler/GHC/CmmToAsm/RV64/Regs.hs - compiler/GHC/CmmToAsm/Reg/Graph/TrivColorable.hs - compiler/GHC/CmmToAsm/Wasm/FromCmm.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToAsm/X86/Ppr.hs - compiler/GHC/CmmToAsm/X86/Regs.hs - compiler/GHC/CmmToC.hs - compiler/GHC/CmmToLlvm/CodeGen.hs - compiler/GHC/CmmToLlvm/Data.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Make.hs - compiler/GHC/Core/Opt/ConstantFold.hs - compiler/GHC/Driver/Config/StgToCmm.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Foreign/C.hs - compiler/GHC/HsToCore/Match/Literal.hs - compiler/GHC/HsToCore/Pmc.hs - compiler/GHC/HsToCore/Pmc/Solver/Types.hs - + compiler/GHC/Platform/Tag.hs - compiler/GHC/Stg/Unarise.hs - compiler/GHC/StgToByteCode.hs - compiler/GHC/StgToCmm/Closure.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Lit.hs - compiler/GHC/StgToCmm/Prim.hs - compiler/GHC/StgToJS/Literal.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Instance/Class.hs - compiler/GHC/Tc/TyCl/Build.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Types/Id/Make.hs - compiler/GHC/Types/Literal.hs - + compiler/GHC/Types/Literal/Floating.hs - compiler/GHC/Types/RepType.hs - compiler/GHC/Utils/Binary.hs - compiler/ghc.cabal.in - docs/users_guide/9.16.1-notes.rst - docs/users_guide/utils.py - ghc/GHCi/UI.hs - ghc/Main.hs - hadrian/cabal.project - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Flavours/Validate.hs - hadrian/src/Settings/Packages.hs - libraries/ghc-experimental/ghc-experimental.cabal.in - + libraries/ghc-experimental/src/GHC/Stack/Decode/Experimental.hs - libraries/ghc-internal/src/GHC/Internal/Conc/IO.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Event/KQueue.hsc - libraries/ghc-internal/src/GHC/Internal/Float.hs - libraries/ghc-internal/src/GHC/Internal/Float/RealFracMethods.hs - libraries/ghc-internal/src/GHC/Internal/IO/FD.hs - libraries/ghc-internal/src/GHC/Internal/Int.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/RTS/Flags/Test.hsc - libraries/ghc-internal/src/GHC/Internal/System/Environment.hs - libraries/ghc-internal/src/GHC/Internal/System/Environment/Blank.hsc - libraries/ghc-internal/src/GHC/Internal/System/IO.hs - libraries/ghc-internal/src/GHC/Internal/System/Posix/Internals.hs - libraries/ghc-internal/src/GHC/Internal/TopHandler.hs - libraries/ghci/GHCi/Message.hs - libraries/ghci/GHCi/ResolvedBCO.hs - libraries/ghci/GHCi/Run.hs - libraries/ghci/GHCi/Server.hs - − m4/fp_check_timer_create.m4 - rts/Interpreter.c - rts/PrimOps.cmm - rts/Timer.c - rts/configure.ac - rts/include/rts/Timer.h - rts/include/stg/Prim.h - rts/include/stg/SMP.h - rts/js/arith.js - + rts/posix/FdWakeup.c - + rts/posix/FdWakeup.h - rts/posix/Signals.c - rts/posix/Signals.h - rts/posix/Ticker.c - − rts/posix/ticker/Pthread.c - − rts/posix/ticker/Setitimer.c - − rts/posix/ticker/TimerCreate.c - − rts/posix/ticker/TimerFd.c - rts/prim/vectorQuotRem.c - rts/rts.cabal - + testsuite/tests/bytecode/T27001.hs - + testsuite/tests/bytecode/T27001.stdout - testsuite/tests/bytecode/all.T - + testsuite/tests/codeGen/should_run/T21227.hs - + testsuite/tests/codeGen/should_run/T21227.stdout - + testsuite/tests/codeGen/should_run/T9811.hs - + testsuite/tests/codeGen/should_run/T9811.stdout - testsuite/tests/codeGen/should_run/all.T - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - + testsuite/tests/driver/T13729/A/A.cabal - + testsuite/tests/driver/T13729/A/Setup.hs - + testsuite/tests/driver/T13729/A/TH.hs - + testsuite/tests/driver/T13729/A/Types1.hs - + testsuite/tests/driver/T13729/A/Types2.hs - + testsuite/tests/driver/T13729/B/B.cabal - + testsuite/tests/driver/T13729/B/Main.hs - + testsuite/tests/driver/T13729/B/Setup.hs - + testsuite/tests/driver/T13729/Makefile - + testsuite/tests/driver/T13729/Setup.hs - + testsuite/tests/driver/T13729/all.T - + testsuite/tests/ffi/should_compile/T26852.h - + testsuite/tests/ffi/should_compile/T26852.hs - + testsuite/tests/ffi/should_compile/T26852.stderr - testsuite/tests/ffi/should_compile/all.T - + testsuite/tests/ghci/custom-external-interpreter-commands/Main.hs - + testsuite/tests/ghci/custom-external-interpreter-commands/all.T - + testsuite/tests/ghci/custom-external-interpreter-commands/custom-external-interpreter-commands.stdout - testsuite/tests/ghci/should_run/BinaryArray.hs - testsuite/tests/interface-stability/ghc-experimental-exports.stdout - testsuite/tests/interface-stability/ghc-experimental-exports.stdout-mingw32 - + testsuite/tests/javascript/js-c-sources/T27033.hs - + testsuite/tests/javascript/js-c-sources/T27033.stdout - + testsuite/tests/javascript/js-c-sources/T27033_c.c - + testsuite/tests/javascript/js-c-sources/T27033_js.js - testsuite/tests/javascript/js-c-sources/all.T - testsuite/tests/numeric/should_run/T7014.hs - + testsuite/tests/overloadedrecflds/should_compile/T26686.hs - + testsuite/tests/overloadedrecflds/should_compile/T26686.stderr - testsuite/tests/overloadedrecflds/should_compile/all.T - testsuite/tests/rts/all.T - + testsuite/tests/rts/resizeMutableByteArrayInPlace.hs - + testsuite/tests/simd/should_run/FloatConstant.hs - + testsuite/tests/simd/should_run/FloatConstant.stdout - + testsuite/tests/simd/should_run/IntConstant.hs - + testsuite/tests/simd/should_run/IntConstant.stdout - testsuite/tests/simd/should_run/all.T - testsuite/tests/simd/should_run/int16x8_shuffle.hs - testsuite/tests/simd/should_run/int16x8_shuffle.stdout - testsuite/tests/simd/should_run/int16x8_shuffle_baseline.hs - testsuite/tests/simd/should_run/int16x8_shuffle_baseline.stdout - testsuite/tests/simd/should_run/int8x16_shuffle.hs - testsuite/tests/simd/should_run/int8x16_shuffle.stdout - testsuite/tests/simd/should_run/int8x16_shuffle_baseline.hs - testsuite/tests/simd/should_run/int8x16_shuffle_baseline.stdout - testsuite/tests/simd/should_run/simd013C.c - + testsuite/tests/simplCore/should_compile/T18032.hs - + testsuite/tests/simplCore/should_compile/T18032.stderr - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/simplStg/should_run/all.T - + testsuite/tests/simplStg/should_run/unpack_enum.hs - + testsuite/tests/simplStg/should_run/unpack_enum.stdout The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/21d712cc0fd217bea622e1dadd5863… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/21d712cc0fd217bea622e1dadd5863… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/fendor/linkable-usage] 28 commits: Check that shift values are valid
by Hannes Siebenhandl (＠fendor) 26 Mar '26

26 Mar '26

Hannes Siebenhandl pushed to branch wip/fendor/linkable-usage at Glasgow Haskell Compiler / GHC Commits: aa5dfe67 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - c8a7b588 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - a5ec467e by ARATA Mizuki at 2026-03-26T03:49:49-04:00 rts: Align stack to 64-byte boundary in StgRun on x86 When LLVM spills AVX/AVX-512 vector registers to the stack, it requires 32-byte (__m256) or 64-byte (__m512) alignment. If the stack is not sufficiently aligned, LLVM inserts a realignment prologue that reserves %rbp as a frame pointer, conflicting with GHC's use of %rbp as an STG callee-saved register and breaking the tail-call-based calling convention. Previously, GHC worked around this by lying to LLVM about the stack alignment and rewriting aligned vector loads/stores (VMOVDQA, VMOVAPS) to unaligned ones (VMOVDQU, VMOVUPS) in the LLVM Mangler. This had two problems: - It did not extend to AVX-512, which requires 64-byte alignment. (#26595) - When Haskell calls a C function that takes __m256/__m512 arguments on the stack, the callee requires genuine alignment, which could cause a segfault. (#26822) This patch genuinely aligns the stack to 64 bytes in StgRun by saving the original stack pointer before alignment and restoring it in StgReturn. We now unconditionally advertise 64-byte stack alignment to LLVM for all x86 targets, making rewriteAVX in the LLVM Mangler unnecessary. STG_RUN_STACK_FRAME_SIZE is increased from 48 to 56 bytes on non-Windows x86-64 to store the saved stack pointer. Closes #26595 and #26822 Co-Authored-By: Claude Opus 4.5 <noreply(a)anthropic.com> - - - - - 661da815 by Teo Camarasu at 2026-03-26T03:50:33-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - 45428f88 by sheaf at 2026-03-26T03:51:31-04:00 Avoid infinite loop in deep subsumption This commit ensures we only unify after we recur in the deep subsumption code in the FunTy vs non-FunTy case of GHC.Tc.Utils.Unify.tc_sub_type_deep, to avoid falling into an infinite loop. See the new Wrinkle [Avoiding a loop in tc_sub_type_deep] in Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify. Fixes #26823 Co-authored-by: simonpj <simon.peytonjones(a)gmail.com> - - - - - 2823b039 by Ian Duncan at 2026-03-26T03:52:21-04:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. - - - - - 57b7878d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12002 Closes #12002. - - - - - c8f9df2d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12046 Closes #12046. Co-authored-by: Andreas Klebinger <klebinger.andreas(a)gmx.at> - - - - - 615d72ac by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #13180 Closes #13180. - - - - - 423eebcf by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11141 Closes #11141. - - - - - 286849a4 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11505 Closes #11505. - - - - - 7db149d9 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression perf test for #13820 Closes #13820. - - - - - e73c4adb by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #10381 Closes #10381. - - - - - 5ebcfb57 by Benjamin Maurer at 2026-03-26T03:54:02-04:00 Generate assembly on x86 for word2float (#22252) We used to emit C function call for MO_UF_Conv primitive. Now emits direct assembly instead. Co-Authored-By: Sylvain Henry <sylvain(a)haskus.fr> Co-Authored-By: Claude Sonnet 4.6 <noreply(a)anthropic.com> - - - - - 5b550754 by Matthew Pickering at 2026-03-26T03:54:51-04:00 rts: forward clone-stack messages after TSO migration MSG_CLONE_STACK assumed that the target TSO was still owned by the capability that received the message. This is not always true: the TSO can migrate before the inbox entry is handled. When that happened, handleCloneStackMessage could clone a live stack from the wrong capability and use the wrong capability for allocation and performTryPutMVar, leading to stack sanity failures such as checkStackFrame: weird activation record found on stack. Fix this by passing the current capability into handleCloneStackMessage, rechecking msg->tso->cap at handling time, and forwarding the message if the TSO has migrated. Once ownership matches, use the executing capability consistently for cloneStack, rts_apply, and performTryPutMVar. Fixes #27008 - - - - - ef0a1bd2 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: adopt release tracking ticket from #16816 - - - - - a7f40fd9 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: add a release tracking ticket Brings the information in the release tracking ticket up to date with https://gitlab.haskell.org/ghc/ghc-hq/-/blob/main/release-management.mkd Resolves #26691 - - - - - 161d3285 by Teo Camarasu at 2026-03-26T03:56:18-04:00 Revert "Set default eventlog-flush-interval to 5s" Flushing the eventlog forces a synchronisation of all the capabilities and there was a worry that this might lead to a performance cost for some highly parallel workloads. This reverts commit 66b96e2a591d8e3d60e74af3671344dfe4061cf2. - - - - - 36eed985 by Cheng Shao at 2026-03-26T03:57:03-04:00 ghc-boot: move GHC.Data.SmallArray to ghc-boot This commit moves `GHC.Data.SmallArray` from the `ghc` library to `ghc-boot`, so that it can be used by `ghci` as well: - The `Binary` (from `ghc`) instance of `SmallArray` is moved to `GHC.Utils.Binary` - Util functions `replicateSmallArrayIO`, `mapSmallArrayIO`, `mapSmallArrayM_`, `imapSmallArrayM_` , `smallArrayFromList` and `smallArrayToList` are added - The `Show` instance is added - The `Binary` (from `binary`) instance is added - - - - - fdf828ae by Cheng Shao at 2026-03-26T03:57:03-04:00 compiler: use `Binary` instance of `BCOByteArray` for bytecode objects This commit defines `Binary` (from `compiler`) instance of `BCOByteArray` which serializes the underlying buffer directly, and uses it directly in bytecode object serialization. Previously we reuse the `Binary` (from `binary`) instance, and this change allows us to avoid double-copying via an intermediate `ByteString` when using `put`/`get` in `binnary`. Also see added comment for explanation. - - - - - 3bf62d0a by Cheng Shao at 2026-03-26T03:57:03-04:00 ghci: use SmallArray directly in ResolvedBCO This patch makes ghci use `SmallArray` directly in `ResolvedBCO` when applicable, making the memory representation more compact and reducing marshaling overhead. Closes #27058. - - - - - 3d6492ce by Wen Kokke at 2026-03-26T03:57:53-04:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. - - - - - 7b9a75f0 by Phil Hazelden at 2026-03-26T03:58:37-04:00 Fix build with werror on glibc 2.43. We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same values as defined in glibc prior to 2.43. But in 2.43, glibc changes them to new values, which means we get a warning when redefining them. By `#undef`ing them first, we no longer get a warning. Closes #27076. - - - - - fe6e76c5 by Tobias Haslop at 2026-03-26T03:59:30-04:00 Fix broken Haddock link to Bifunctor class in description of Functor class - - - - - 57d0cdde by fendor at 2026-03-26T10:03:08+01:00 Extract Binary instances to `GHC.ByteCode.Binary` - - - - - b72a4f4c by fendor at 2026-03-26T10:03:09+01:00 Add `seqNonEmpty` for evaluating `NonEmpty a` - - - - - f8e749cb by fendor at 2026-03-26T10:03:56+01:00 Record `LinkableUsage` instead of `Linkable` in `LoaderState` Retaining a ByteCode `Linkable` after it has been loaded retains its `UnlinkedBCO`, keeping it alive for the remainder of the program. This starts accumulating a lot of `UnlinkedBCO` and memory over time. However, the `Linkable` is merely used to later record its usage in `mkObjectUsage`, which is used for recompilation checking. However, this is incorrect, as the interface file and bytecode objects could be in different states, e.g. the interface changes, but the bytecode library hasn't changed so we don't need to recompile and vice versa. By computing a `Fingerprint` for the `ModuleByteCode`, and recording it in the `LinkableUsage`, we know precisely whether the `ByteCode` object on disk is outdated. Thus, parts of this commit just makes sure that we efficiently compute a `Fingerprint` for `ModuleByteCode` and store it in the on-disk representation of `ModuleByteCode`. We change the `LoaderState` to retain `LinkableUsage`, which is smaller representation of a `Linkable`. This allows us to free the unneeded fields of `Linkable` after linking them. We declare the following memory invariants that this commit implements: * No `LinkablePart` should be retained from `LoaderState`. * `Linkable`s should be unloaded after they have been loaded. These invariants are unfortunately tricky to automatically uphold, so we are simply documenting our assumptions for now. We introduce the `linkable-space` test which makes sure that after loading, no `DotGBC` or `UnlinkedBCO` is retained. ------------------------- Metric Increase: MultiLayerModulesTH_OneShot ------------------------- We allocate a bit more, but the peak number of bytes doesn't change. While a bit unfortunate, accepting the metric increase. We add multiple new performance measurements where we were able to observe the desired memory invariants. Further, we add regression tests to validate that the recompilation checker behaves more correct than before. - - - - - b41223b6 by fendor at 2026-03-26T10:03:57+01:00 Fix LinkableUsage test on wasm - - - - - 148 changed files: - + .gitlab/issue_templates/release_tracking.md - + compiler/GHC/ByteCode/Binary.hs - compiler/GHC/ByteCode/Linker.hs - + compiler/GHC/ByteCode/Recomp/Binary.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Cmm/Node.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/Config.hs - compiler/GHC/CmmToLlvm/Mangler.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/Driver/Hooks.hs - compiler/GHC/Driver/Main.hs - compiler/GHC/Driver/Pipeline.hs - compiler/GHC/Driver/Plugins.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Iface/Recomp/Types.hs - compiler/GHC/Linker/ByteCode.hs - compiler/GHC/Linker/Deps.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Linker/Types.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/Runtime/Loader.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Unit/Home/ModInfo.hs - compiler/GHC/Unit/Module/Deps.hs - compiler/GHC/Unit/Module/Status.hs - compiler/GHC/Utils/Binary.hs - compiler/GHC/Utils/Misc.hs - compiler/ghc.cabal.in - docs/users_guide/9.16.1-notes.rst - ghc/GHCi/Leak.hs - compiler/GHC/Data/SmallArray.hs → libraries/ghc-boot/GHC/Data/SmallArray.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/Generics.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/Read.hs - libraries/ghc-internal/src/GHC/Internal/Unicode/Bits.hs - libraries/ghci/GHCi/CreateBCO.hs - libraries/ghci/GHCi/ResolvedBCO.hs - rts/CloneStack.c - rts/CloneStack.h - rts/Messages.c - rts/RtsFlags.c - rts/StgCRun.c - rts/eventlog/EventLog.c - rts/include/rts/Constants.h - rts/include/rts/PosixSource.h - 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+ testsuite/tests/simd/should_run/StackAlignment32.hs - + testsuite/tests/simd/should_run/StackAlignment32.stdout - + testsuite/tests/simd/should_run/StackAlignment32_main.c - + testsuite/tests/simd/should_run/StackAlignment64.hs - + testsuite/tests/simd/should_run/StackAlignment64.stdout - + testsuite/tests/simd/should_run/StackAlignment64_main.c - testsuite/tests/simd/should_run/all.T - + testsuite/tests/simplCore/should_compile/T19166.hs - + testsuite/tests/simplCore/should_compile/T19166.stderr - + testsuite/tests/simplCore/should_compile/T25718.hs - + testsuite/tests/simplCore/should_compile/T25718.stderr - + testsuite/tests/simplCore/should_compile/T25718a.hs - + testsuite/tests/simplCore/should_compile/T25718a.stderr - + testsuite/tests/simplCore/should_compile/T25718b.hs - + testsuite/tests/simplCore/should_compile/T25718b.stderr - + testsuite/tests/simplCore/should_compile/T25718c.hs - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/all.T - + testsuite/tests/typecheck/T13180/T13180.hs - + testsuite/tests/typecheck/T13180/T13180.hs-boot - + testsuite/tests/typecheck/T13180/T13180.stderr - + testsuite/tests/typecheck/T13180/T13180A.hs - + testsuite/tests/typecheck/T13180/all.T - + testsuite/tests/typecheck/should_compile/T11141.hs - + testsuite/tests/typecheck/should_compile/T11141.stderr - + testsuite/tests/typecheck/should_compile/T11505Bar.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs-boot - + testsuite/tests/typecheck/should_compile/T12046.hs - testsuite/tests/typecheck/should_compile/T26225.hs - testsuite/tests/typecheck/should_compile/all.T - + testsuite/tests/typecheck/should_fail/T26823.hs - + testsuite/tests/typecheck/should_fail/T26823.stderr - testsuite/tests/typecheck/should_fail/all.T The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c7abbce1bc70fae935e6b2fca631b5… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c7abbce1bc70fae935e6b2fca631b5… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/fendor/linkable-usage] 2 commits: Record `LinkableUsage` instead of `Linkable` in `LoaderState`
by Hannes Siebenhandl (＠fendor) 26 Mar '26

26 Mar '26

Hannes Siebenhandl pushed to branch wip/fendor/linkable-usage at Glasgow Haskell Compiler / GHC Commits: 6352c5e9 by fendor at 2026-03-26T09:57:37+01:00 Record `LinkableUsage` instead of `Linkable` in `LoaderState` Retaining a ByteCode `Linkable` after it has been loaded retains its `UnlinkedBCO`, keeping it alive for the remainder of the program. This starts accumulating a lot of `UnlinkedBCO` and memory over time. However, the `Linkable` is merely used to later record its usage in `mkObjectUsage`, which is used for recompilation checking. However, this is incorrect, as the interface file and bytecode objects could be in different states, e.g. the interface changes, but the bytecode library hasn't changed so we don't need to recompile and vice versa. By computing a `Fingerprint` for the `ModuleByteCode`, and recording it in the `LinkableUsage`, we know precisely whether the `ByteCode` object on disk is outdated. Thus, parts of this commit just makes sure that we efficiently compute a `Fingerprint` for `ModuleByteCode` and store it in the on-disk representation of `ModuleByteCode`. We change the `LoaderState` to retain `LinkableUsage`, which is smaller representation of a `Linkable`. This allows us to free the unneeded fields of `Linkable` after linking them. We declare the following memory invariants that this commit implements: * No `LinkablePart` should be retained from `LoaderState`. * `Linkable`s should be unloaded after they have been loaded. These invariants are unfortunately tricky to automatically uphold, so we are simply documenting our assumptions for now. We introduce the `linkable-space` test which makes sure that after loading, no `DotGBC` or `UnlinkedBCO` is retained. ------------------------- Metric Increase: MultiLayerModulesTH_OneShot ------------------------- We allocate a bit more, but the peak number of bytes doesn't change. While a bit unfortunate, accepting the metric increase. We add multiple new performance measurements where we were able to observe the desired memory invariants. Further, we add regression tests to validate that the recompilation checker behaves more correct than before. - - - - - c7abbce1 by fendor at 2026-03-26T09:57:51+01:00 Fix LinkableUsage test on wasm - - - - - 42 changed files: - compiler/GHC/ByteCode/Binary.hs - + compiler/GHC/ByteCode/Recomp/Binary.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Driver/Hooks.hs - compiler/GHC/Driver/Main.hs - compiler/GHC/Driver/Pipeline.hs - compiler/GHC/Driver/Plugins.hs - compiler/GHC/HsToCore/Usage.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Iface/Recomp/Types.hs - compiler/GHC/Linker/ByteCode.hs - compiler/GHC/Linker/Deps.hs - compiler/GHC/Linker/Loader.hs - compiler/GHC/Linker/Types.hs - compiler/GHC/Runtime/Loader.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Unit/Home/ModInfo.hs - compiler/GHC/Unit/Module/Deps.hs - compiler/GHC/Unit/Module/Status.hs - compiler/ghc.cabal.in - ghc/GHCi/Leak.hs - + testsuite/tests/bytecode/TLinkable/BCOTemplate.hs - + testsuite/tests/bytecode/TLinkable/LinkableUsage01.stderr - + testsuite/tests/bytecode/TLinkable/LinkableUsage02.stderr - + testsuite/tests/bytecode/TLinkable/Makefile - + testsuite/tests/bytecode/TLinkable/all.T - + testsuite/tests/bytecode/TLinkable/genLinkables.sh - + testsuite/tests/bytecode/TLinkable/linkable-space.hs - + testsuite/tests/bytecode/TLinkable/linkable-space.stdout - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - testsuite/tests/driver/multipleHomeUnits/multipleHomeUnits_recomp_th.stdout - + testsuite/tests/driver/recomp022/A1.hs - + testsuite/tests/driver/recomp022/A2.hs - + testsuite/tests/driver/recomp022/A3.hs - + testsuite/tests/driver/recomp022/B.hs - + testsuite/tests/driver/recomp022/C.hs - + testsuite/tests/driver/recomp022/Makefile - + testsuite/tests/driver/recomp022/all.T - + testsuite/tests/driver/recomp022/recomp022a.stdout - + testsuite/tests/driver/recomp022/recomp022b.stdout The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c85f11afd7e8b342653797d2f493ab… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/c85f11afd7e8b342653797d2f493ab… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 28 commits: Check that shift values are valid
by Marge Bot (＠marge-bot) 26 Mar '26

26 Mar '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: aa5dfe67 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Check that shift values are valid In GHC's codebase in non-DEBUG builds we silently substitute shiftL/R with unsafeShiftL/R for performance reasons. However we were not checking that the shift value was valid for unsafeShiftL/R, leading to wrong computations, but only in non-DEBUG builds. This patch adds the necessary checks and reports an error when a wrong shift value is passed. - - - - - c8a7b588 by Sylvain Henry at 2026-03-26T03:48:56-04:00 Implement basic value range analysis (#25718) Perform basic value range analysis to try to determine at compile time the result of the application of some comparison primops (ltWord#, etc.). This subsumes the built-in rewrite rules used previously to check if one of the comparison argument was a bound (e.g. (x :: Word8) <= 255 is always True). Our analysis is more powerful and handles type conversions: e.g. word8ToWord x <= 255 is now detected as always True too. We also use value range analysis to filter unreachable alternatives in case-expressions. To support this, we had to allow case-expressions for primitive types to not have a DEFAULT alternative (as was assumed before and checked in Core lint). - - - - - a5ec467e by ARATA Mizuki at 2026-03-26T03:49:49-04:00 rts: Align stack to 64-byte boundary in StgRun on x86 When LLVM spills AVX/AVX-512 vector registers to the stack, it requires 32-byte (__m256) or 64-byte (__m512) alignment. If the stack is not sufficiently aligned, LLVM inserts a realignment prologue that reserves %rbp as a frame pointer, conflicting with GHC's use of %rbp as an STG callee-saved register and breaking the tail-call-based calling convention. Previously, GHC worked around this by lying to LLVM about the stack alignment and rewriting aligned vector loads/stores (VMOVDQA, VMOVAPS) to unaligned ones (VMOVDQU, VMOVUPS) in the LLVM Mangler. This had two problems: - It did not extend to AVX-512, which requires 64-byte alignment. (#26595) - When Haskell calls a C function that takes __m256/__m512 arguments on the stack, the callee requires genuine alignment, which could cause a segfault. (#26822) This patch genuinely aligns the stack to 64 bytes in StgRun by saving the original stack pointer before alignment and restoring it in StgReturn. We now unconditionally advertise 64-byte stack alignment to LLVM for all x86 targets, making rewriteAVX in the LLVM Mangler unnecessary. STG_RUN_STACK_FRAME_SIZE is increased from 48 to 56 bytes on non-Windows x86-64 to store the saved stack pointer. Closes #26595 and #26822 Co-Authored-By: Claude Opus 4.5 <noreply(a)anthropic.com> - - - - - 661da815 by Teo Camarasu at 2026-03-26T03:50:33-04:00 ghc-internal: Float Generics to near top of module graph We remove GHC.Internal.Generics from the critical path of the `ghc-internal` module graph. GHC.Internal.Generics used to be in the middle of the module graph, but now it is nearer the top (built later). This change thins out the module graph and allows us to get rid of the ByteOrder hs-boot file. We implement this by moving Generics instances from the module where the datatype is defined to the GHC.Internal.Generics module. This trades off increasing the compiled size of GHC.Internal.Generics with reducing the dependency footprint of datatype modules. Not all instances are moved to GHC.Internal.Generics. For instance, `GHC.Internal.Control.Monad.Fix` keeps its instance as it is one of the very last modules compiled in `ghc-internal` and so inverting the relationship here would risk adding GHC.Internal.Generics back onto the critical path. We also don't change modules that are re-exported from the `template-haskell` or `ghc-heap`. This is done to make it easy to eventually move `Generics` to `base` once something like #26657 is implemented. Resolves #26930 Metric Decrease: T21839c - - - - - 45428f88 by sheaf at 2026-03-26T03:51:31-04:00 Avoid infinite loop in deep subsumption This commit ensures we only unify after we recur in the deep subsumption code in the FunTy vs non-FunTy case of GHC.Tc.Utils.Unify.tc_sub_type_deep, to avoid falling into an infinite loop. See the new Wrinkle [Avoiding a loop in tc_sub_type_deep] in Note [FunTy vs non-FunTy case in tc_sub_type_deep] in GHC.Tc.Utils.Unify. Fixes #26823 Co-authored-by: simonpj <simon.peytonjones(a)gmail.com> - - - - - 2823b039 by Ian Duncan at 2026-03-26T03:52:21-04:00 AArch64: fix MOVK regUsageOfInstr to mark dst as both read and written MOVK (move with keep) modifies only a 16-bit slice of the destination register, so the destination is both read and written. The register allocator must know this to avoid clobbering live values. Update regUsageOfInstr to list the destination in both src and dst sets. No regression test: triggering the misallocation requires specific register pressure around a MOVK sequence, which is difficult to reliably provoke from Haskell source. - - - - - 57b7878d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12002 Closes #12002. - - - - - c8f9df2d by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #12046 Closes #12046. Co-authored-by: Andreas Klebinger <klebinger.andreas(a)gmx.at> - - - - - 615d72ac by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #13180 Closes #13180. - - - - - 423eebcf by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11141 Closes #11141. - - - - - 286849a4 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #11505 Closes #11505. - - - - - 7db149d9 by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression perf test for #13820 Closes #13820. - - - - - e73c4adb by Simon Jakobi at 2026-03-26T03:53:07-04:00 Add regression test for #10381 Closes #10381. - - - - - 5ebcfb57 by Benjamin Maurer at 2026-03-26T03:54:02-04:00 Generate assembly on x86 for word2float (#22252) We used to emit C function call for MO_UF_Conv primitive. Now emits direct assembly instead. Co-Authored-By: Sylvain Henry <sylvain(a)haskus.fr> Co-Authored-By: Claude Sonnet 4.6 <noreply(a)anthropic.com> - - - - - 5b550754 by Matthew Pickering at 2026-03-26T03:54:51-04:00 rts: forward clone-stack messages after TSO migration MSG_CLONE_STACK assumed that the target TSO was still owned by the capability that received the message. This is not always true: the TSO can migrate before the inbox entry is handled. When that happened, handleCloneStackMessage could clone a live stack from the wrong capability and use the wrong capability for allocation and performTryPutMVar, leading to stack sanity failures such as checkStackFrame: weird activation record found on stack. Fix this by passing the current capability into handleCloneStackMessage, rechecking msg->tso->cap at handling time, and forwarding the message if the TSO has migrated. Once ownership matches, use the executing capability consistently for cloneStack, rts_apply, and performTryPutMVar. Fixes #27008 - - - - - ef0a1bd2 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: adopt release tracking ticket from #16816 - - - - - a7f40fd9 by mangoiv at 2026-03-26T03:55:34-04:00 release tracking: add a release tracking ticket Brings the information in the release tracking ticket up to date with https://gitlab.haskell.org/ghc/ghc-hq/-/blob/main/release-management.mkd Resolves #26691 - - - - - 161d3285 by Teo Camarasu at 2026-03-26T03:56:18-04:00 Revert "Set default eventlog-flush-interval to 5s" Flushing the eventlog forces a synchronisation of all the capabilities and there was a worry that this might lead to a performance cost for some highly parallel workloads. This reverts commit 66b96e2a591d8e3d60e74af3671344dfe4061cf2. - - - - - 36eed985 by Cheng Shao at 2026-03-26T03:57:03-04:00 ghc-boot: move GHC.Data.SmallArray to ghc-boot This commit moves `GHC.Data.SmallArray` from the `ghc` library to `ghc-boot`, so that it can be used by `ghci` as well: - The `Binary` (from `ghc`) instance of `SmallArray` is moved to `GHC.Utils.Binary` - Util functions `replicateSmallArrayIO`, `mapSmallArrayIO`, `mapSmallArrayM_`, `imapSmallArrayM_` , `smallArrayFromList` and `smallArrayToList` are added - The `Show` instance is added - The `Binary` (from `binary`) instance is added - - - - - fdf828ae by Cheng Shao at 2026-03-26T03:57:03-04:00 compiler: use `Binary` instance of `BCOByteArray` for bytecode objects This commit defines `Binary` (from `compiler`) instance of `BCOByteArray` which serializes the underlying buffer directly, and uses it directly in bytecode object serialization. Previously we reuse the `Binary` (from `binary`) instance, and this change allows us to avoid double-copying via an intermediate `ByteString` when using `put`/`get` in `binnary`. Also see added comment for explanation. - - - - - 3bf62d0a by Cheng Shao at 2026-03-26T03:57:03-04:00 ghci: use SmallArray directly in ResolvedBCO This patch makes ghci use `SmallArray` directly in `ResolvedBCO` when applicable, making the memory representation more compact and reducing marshaling overhead. Closes #27058. - - - - - 3d6492ce by Wen Kokke at 2026-03-26T03:57:53-04:00 Fix race condition between flushEventLog and start/endEventLogging. This commit changes `flushEventLog` to acquire/release the `state_change` mutex to prevent interleaving with `startEventLogging` and `endEventLogging`. In the current RTS, `flushEventLog` _does not_ acquire this mutex, which may lead to eventlog corruption on the following interleaving: - `startEventLogging` writes the new `EventLogWriter` to `event_log_writer`. - `flushEventLog` flushes some events to `event_log_writer`. - `startEventLogging` writes the eventlog header to `event_log_writer`. This causes the eventlog to be written out in an unreadable state, with one or more events preceding the eventlog header. This commit renames the old function to `flushEventLog_` and defines `flushEventLog` simply as: ```c void flushEventLog(Capability **cap USED_IF_THREADS) { ACQUIRE_LOCK(&state_change_mutex); flushEventLog_(cap); RELEASE_LOCK(&state_change_mutex); } ``` The old function is still needed internally within the compilation unit, where it is used in `endEventLogging` in a context where the `state_change` mutex has already been acquired. I've chosen to mark `flushEventLog_` as static and let other uses of `flushEventLog` within the RTS refer to the new version. There is one use in `hs_init_ghc` via `flushTrace`, where the new locking behaviour should be harmless, and one use in `handle_tick`, which I believe was likely vulnerable to the same race condition, so the new locking behaviour is desirable. I have not added a test. The behaviour is highly non-deterministic and requires a program that concurrently calls `flushEventLog` and `startEventLogging`/`endEventLogging`. I encountered the issue while developing `eventlog-socket` and within that context have verified that my patch likely addresses the issue: a test that used to fail within the first dozen or so runs now has been running on repeat for several hours. - - - - - 7b9a75f0 by Phil Hazelden at 2026-03-26T03:58:37-04:00 Fix build with werror on glibc 2.43. We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same values as defined in glibc prior to 2.43. But in 2.43, glibc changes them to new values, which means we get a warning when redefining them. By `#undef`ing them first, we no longer get a warning. Closes #27076. - - - - - fe6e76c5 by Tobias Haslop at 2026-03-26T03:59:30-04:00 Fix broken Haddock link to Bifunctor class in description of Functor class - - - - - e4d6c2ce by Vladislav Zavialov at 2026-03-26T04:32:51-04:00 Extend HsExpr with the StarIsType syntax (#26587, #26967) This patch allows kinds of the form `k -> *` and `* -> k` to occur in expression syntax, i.e. to be used as required type arguments. For example: {-# LANGUAGE RequiredTypeArguments, StarIsType #-} x1 = f (* -> * -> *) x2 = f (forall k. k -> *) x3 = f ((* -> *) -> Constraint) Summary of the changes: * Introduce the HsStar constructor of HsExpr and its extension field XStar. It is analogous to HsStarTy in HsType. * Refactor HsStarTy to store the unicode flag as TokStar, defined as type TokStar = EpUniToken "*" "★" -- similar to TokForall, TokRArrow, etc. The token is stored in the extension field and replaces the Bool field. * Extend the `infixexp2` nonterminal to parse `*` as a direct argument of `->`. This is more limited than the full StarIsType syntax, but has the nice property of not conflicting with the multiplication operator `a * b`. Test case: T26967 T26967_tyop - - - - - a6f8d2fe by Sylvain Henry at 2026-03-26T04:32:59-04:00 STM: don't create a transaction in the rhs of catchRetry# (#26028) We don't need to create a transaction for the rhs of (catchRetry#) because contrary to the lhs we don't need to abort it on retry. Moreover it is particularly harmful if we have code such as (#26028): let cN = readTVar vN >> retry tree = c1 `orElse` (c2 `orElse` (c3 `orElse` ...)) atomically tree Because it will stack transactions for the rhss and the read-sets of all the transactions will be iteratively merged in O(n^2) after the execution of the most nested retry. This is the second attempt at implementing this. The first attempt triggered segfaults (#26291) and has been reverted. Co-Authored-By: Claude Sonnet 4.6 <noreply(a)anthropic.com> - - - - - d63a71a2 by Luite Stegeman at 2026-03-26T04:33:13-04:00 Don't refine DEFAULT alt for unary typeclasses A non-DEFAULT data alt for a unary typeclass dictionary would interfere with Unary Class Magic, leading to segfaults. fixes #27071 - - - - - 966b39d4 by sheaf at 2026-03-26T04:33:19-04:00 Fix several oversights in hsExprType This commit fixes several oversights in GHC.Hs.Syn.Type.hsExprType: - The 'RecordCon' case was returning the type of the constructor, instead of the constructor application. This is fixed by using 'splitFunTys'. - The 'ExplicitTuple' case failed to take into account tuple sections, and was also incorrectly handling 1-tuples (e.g. 'Solo') which can be constructed using Template Haskell. - The 'NegApp' case was returning the type of the negation operator, again failing to apply it to the argument. Fixed by using 'funResultTy'. - The 'HsProc' case was computing the result type of the arrow proc block, without taking into account the argument type. Fix that by adding a new field to 'CmdTopTc' that stores the arrow type, so that we can construct the correct result type `arr a b` for `proc (pat :: a) -> (cmd :: b)`. - The 'ArithSeq' and 'NegApp' cases were failing to take into account the result 'HsWrapper', which could e.g. silently drop casts. This is fixed by introducing 'syntaxExpr_wrappedFunResTy' which, on top of taking the result type, applies the result 'HsWrapper'. These fixes are validated by the new GHC API test T26910. Fixes #26910 - - - - - 169 changed files: - + .gitlab/issue_templates/release_tracking.md - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/Cmm/Node.hs - compiler/GHC/CmmToAsm/AArch64/Instr.hs - compiler/GHC/CmmToAsm/X86/CodeGen.hs - compiler/GHC/CmmToLlvm.hs - compiler/GHC/CmmToLlvm/Config.hs - compiler/GHC/CmmToLlvm/Mangler.hs - compiler/GHC/Core.hs - compiler/GHC/Core/Lint.hs - compiler/GHC/Core/Opt/ConstantFold.hs - + compiler/GHC/Core/Opt/Range.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/TyCon.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/Syn/Type.hs - compiler/GHC/Hs/Type.hs - compiler/GHC/HsToCore/Arrows.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Type.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/Errors/Types.hs - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Arrow.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/Utils/Binary.hs - compiler/GHC/Utils/Outputable.hs - compiler/Language/Haskell/Syntax/Expr.hs - compiler/Language/Haskell/Syntax/Extension.hs - compiler/Language/Haskell/Syntax/Type.hs - compiler/ghc.cabal.in - docs/users_guide/9.16.1-notes.rst - docs/users_guide/exts/required_type_arguments.rst - compiler/GHC/Data/SmallArray.hs → libraries/ghc-boot/GHC/Data/SmallArray.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-internal/src/GHC/Internal/Base.hs - libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs - − libraries/ghc-internal/src/GHC/Internal/ByteOrder.hs-boot - libraries/ghc-internal/src/GHC/Internal/Char.hs - libraries/ghc-internal/src/GHC/Internal/Data/Foldable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Const.hs - libraries/ghc-internal/src/GHC/Internal/Data/Functor/Identity.hs - libraries/ghc-internal/src/GHC/Internal/Data/Monoid.hs - libraries/ghc-internal/src/GHC/Internal/Data/Semigroup/Internal.hs - libraries/ghc-internal/src/GHC/Internal/Data/Traversable.hs - libraries/ghc-internal/src/GHC/Internal/Data/Version.hs - libraries/ghc-internal/src/GHC/Internal/Event/Control.hs - libraries/ghc-internal/src/GHC/Internal/Functor/ZipList.hs - libraries/ghc-internal/src/GHC/Internal/Generics.hs - libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs - libraries/ghc-internal/src/GHC/Internal/RTS/Flags.hsc - libraries/ghc-internal/src/GHC/Internal/Read.hs - libraries/ghc-internal/src/GHC/Internal/Unicode/Bits.hs - libraries/ghci/GHCi/CreateBCO.hs - libraries/ghci/GHCi/ResolvedBCO.hs - rts/CloneStack.c - rts/CloneStack.h - rts/Messages.c - rts/PrimOps.cmm - rts/RaiseAsync.c - rts/RtsFlags.c - rts/STM.c - rts/STM.h - rts/Schedule.c - rts/StgCRun.c - rts/eventlog/EventLog.c - rts/include/rts/Constants.h - rts/include/rts/PosixSource.h - testsuite/tests/codeGen/should_run/Word2Float32.hs - testsuite/tests/codeGen/should_run/Word2Float32.stdout - testsuite/tests/codeGen/should_run/Word2Float64.hs - testsuite/tests/codeGen/should_run/Word2Float64.stdout - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - + testsuite/tests/ghc-api/T26910.hs - + testsuite/tests/ghc-api/T26910.stdout - + testsuite/tests/ghc-api/T26910_Input.hs - testsuite/tests/ghc-api/all.T - testsuite/tests/ghci/scripts/ListTuplePunsPpr.stdout - testsuite/tests/ghci/scripts/T10963.stderr - testsuite/tests/ghci/scripts/ghci064.stdout - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 - + testsuite/tests/lib/stm/T26028.hs - + testsuite/tests/lib/stm/T26028.stdout - + testsuite/tests/lib/stm/T26291a.hs - + testsuite/tests/lib/stm/T26291a.stdout - + testsuite/tests/lib/stm/T26291b.hs - + testsuite/tests/lib/stm/T26291b.stdout - + testsuite/tests/lib/stm/all.T - + testsuite/tests/parser/should_compile/T12002.hs - + testsuite/tests/parser/should_compile/T12002.stderr - testsuite/tests/parser/should_compile/all.T - + testsuite/tests/perf/compiler/T13820.hs - testsuite/tests/perf/compiler/all.T - + testsuite/tests/rebindable/T10381.hs - testsuite/tests/rebindable/all.T - testsuite/tests/rts/all.T - + testsuite/tests/rts/cloneThreadStackMigrating.hs - + testsuite/tests/simd/should_run/StackAlignment32.hs - + testsuite/tests/simd/should_run/StackAlignment32.stdout - + testsuite/tests/simd/should_run/StackAlignment32_main.c - + testsuite/tests/simd/should_run/StackAlignment64.hs - + testsuite/tests/simd/should_run/StackAlignment64.stdout - + testsuite/tests/simd/should_run/StackAlignment64_main.c - testsuite/tests/simd/should_run/all.T - + testsuite/tests/simplCore/should_compile/T19166.hs - + testsuite/tests/simplCore/should_compile/T19166.stderr - + testsuite/tests/simplCore/should_compile/T25718.hs - + testsuite/tests/simplCore/should_compile/T25718.stderr - + testsuite/tests/simplCore/should_compile/T25718a.hs - + testsuite/tests/simplCore/should_compile/T25718a.stderr - + testsuite/tests/simplCore/should_compile/T25718b.hs - + testsuite/tests/simplCore/should_compile/T25718b.stderr - + testsuite/tests/simplCore/should_compile/T25718c.hs - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-32 - + testsuite/tests/simplCore/should_compile/T25718c.stderr-ws-64 - testsuite/tests/simplCore/should_compile/all.T - + testsuite/tests/simplCore/should_run/T27071.hs - + testsuite/tests/simplCore/should_run/T27071.stdout - testsuite/tests/simplCore/should_run/all.T - + testsuite/tests/typecheck/T13180/T13180.hs - + testsuite/tests/typecheck/T13180/T13180.hs-boot - + testsuite/tests/typecheck/T13180/T13180.stderr - + testsuite/tests/typecheck/T13180/T13180A.hs - + testsuite/tests/typecheck/T13180/all.T - + testsuite/tests/typecheck/should_compile/T11141.hs - + testsuite/tests/typecheck/should_compile/T11141.stderr - + testsuite/tests/typecheck/should_compile/T11505Bar.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs - + testsuite/tests/typecheck/should_compile/T11505Foo.hs-boot - + testsuite/tests/typecheck/should_compile/T12046.hs - testsuite/tests/typecheck/should_compile/T26225.hs - testsuite/tests/typecheck/should_compile/all.T - + testsuite/tests/typecheck/should_fail/T26823.hs - + testsuite/tests/typecheck/should_fail/T26823.stderr - testsuite/tests/typecheck/should_fail/all.T - + testsuite/tests/vdq-rta/should_compile/T26967.hs - + testsuite/tests/vdq-rta/should_compile/T26967.stderr - + testsuite/tests/vdq-rta/should_compile/T26967_tyop.hs - + testsuite/tests/vdq-rta/should_compile/T26967_tyop.stderr - testsuite/tests/vdq-rta/should_compile/all.T - utils/check-exact/ExactPrint.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Interface/RenameType.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f3fe26e88536cb089e256fe50f035d… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f3fe26e88536cb089e256fe50f035d… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] Fix broken Haddock link to Bifunctor class in description of Functor class
by Marge Bot (＠marge-bot) 26 Mar '26

26 Mar '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: fe6e76c5 by Tobias Haslop at 2026-03-26T03:59:30-04:00 Fix broken Haddock link to Bifunctor class in description of Functor class - - - - - 1 changed file: - libraries/ghc-internal/src/GHC/Internal/Base.hs Changes: ===================================== libraries/ghc-internal/src/GHC/Internal/Base.hs ===================================== @@ -961,7 +961,7 @@ class Functor f where -- Note that for any type constructor with more than one parameter (e.g., 'Either'), -- only the last type parameter can be modified with `fmap` (e.g., `b` in @Either a b@). -- - -- Some type constructors with two parameters or more have a @'Data.Bifunctor'@ instance that allows + -- Some type constructors with two parameters or more have a @'Data.Bifunctor.Bifunctor'@ instance that allows -- both the last and the penultimate parameters to be mapped over. -- -- ==== __Examples__ View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fe6e76c5e0155b9b34948957476b0bb… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fe6e76c5e0155b9b34948957476b0bb… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][master] Fix build with werror on glibc 2.43.
by Marge Bot (＠marge-bot) 26 Mar '26

26 Mar '26

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 7b9a75f0 by Phil Hazelden at 2026-03-26T03:58:37-04:00 Fix build with werror on glibc 2.43. We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same values as defined in glibc prior to 2.43. But in 2.43, glibc changes them to new values, which means we get a warning when redefining them. By `#undef`ing them first, we no longer get a warning. Closes #27076. - - - - - 1 changed file: - rts/include/rts/PosixSource.h Changes: ===================================== rts/include/rts/PosixSource.h ===================================== @@ -29,6 +29,8 @@ Oracle's Solaris 11 supports only up to XPG6, hence the ifdef. */ +#undef _POSIX_C_SOURCE +#undef _XOPEN_SOURCE #if defined(solaris2_HOST_OS) #define _POSIX_C_SOURCE 200112L #define _XOPEN_SOURCE 600 View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7b9a75f09a0a8d11d843f43e8e938b6… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7b9a75f09a0a8d11d843f43e8e938b6… You're receiving this email because of your account on gitlab.haskell.org.

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