March 2026 - ghc-commits

[Git][ghc/ghc] Pushed new branch wip/better-error-for-chr
by Bodigrim (＠Bodigrim) 28 Mar '26

28 Mar '26

Bodigrim pushed new branch wip/better-error-for-chr at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/better-error-for-chr You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new branch wip/sjakobi/T27115
by Simon Jakobi (＠sjakobi2) 28 Mar '26

28 Mar '26

Simon Jakobi pushed new branch wip/sjakobi/T27115 at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/T27115 You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new branch wip/sjakobi/T27106
by Simon Jakobi (＠sjakobi2) 28 Mar '26

28 Mar '26

Simon Jakobi pushed new branch wip/sjakobi/T27106 at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/T27106 You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new branch wip/int-index/low-hanging-unify
by Vladislav Zavialov (＠int-index) 28 Mar '26

28 Mar '26

Vladislav Zavialov pushed new branch wip/int-index/low-hanging-unify at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/int-index/low-hanging-unify You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/supersven/correctly_propagate_host-build-target] Respect user set CFLAGS, CXXFLAGS, LDFLAGS, etc.
by Sven Tennie (＠supersven) 28 Mar '26

28 Mar '26

Sven Tennie pushed to branch wip/supersven/correctly_propagate_host-build-target at Glasgow Haskell Compiler / GHC Commits: 0ff88825 by Sven Tennie at 2026-03-28T07:47:47+01:00 Respect user set CFLAGS, CXXFLAGS, LDFLAGS, etc. These were ignored on installs. - - - - - 1 changed file: - distrib/configure.ac.in Changes: ===================================== distrib/configure.ac.in ===================================== @@ -153,12 +153,38 @@ AC_SUBST([EnableStrictGhcToolchainCheck]) dnl ** Which gcc to use? dnl -------------------------------------------------------------- + +dnl AC_PROG_CC sets CFLAGS to `-g -O2` if the env var is empty. +dnl Same goes for AC_PROG_CXX and CXXFLAGS. Setting the vars prevents this. +dnl (`-g` increases binary sizes with debugging symbols. `-O2` may optimize +dnl symbols away, confusing the RTS linker.) +: ${CFLAGS=""} +: ${CXXFLAGS=""} + AC_PROG_CC([cc gcc clang]) AC_PROG_CXX([c++ g++ clang++]) # Work around #24324 MOVE_TO_FLAGS([CC],[CFLAGS]) MOVE_TO_FLAGS([CXX],[CXXFLAGS]) +dnl Save the original user-provided environment variables immediately +dnl before any m4 macros modify them. These will be passed to ghc-toolchain +dnl so it can make independent decisions and reach the same conclusions as autoconf. +USER_CONF_CC_OPTS_STAGE2="$CFLAGS" +USER_CONF_CXX_OPTS_STAGE2="$CXXFLAGS" +USER_CONF_GCC_LINKER_OPTS_STAGE2="$LDFLAGS" +USER_CPP_ARGS="$CPPFLAGS" +USER_HS_CPP_ARGS="$HaskellCPPArgs" +USER_JS_CPP_ARGS="$JavaScriptCPPArgs" +USER_CMM_CPP_ARGS="$CmmCPPArgs" + +dnl Initialize CONF_* variables with user-provided environment variables +dnl so that subsequent configure checks modify them and both autoconf and +dnl ghc-toolchain see the same values +CONF_CC_OPTS_STAGE2="$CFLAGS" +CONF_CXX_OPTS_STAGE2="$CXXFLAGS" +CONF_GCC_LINKER_OPTS_STAGE2="$LDFLAGS" + dnl ** figure out how to invoke the C preprocessor (i.e. `gcc -E`) AC_PROG_CPP View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/0ff88825f13c20d4047cba27a03b942… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/0ff88825f13c20d4047cba27a03b942… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/supersven/correctly_propagate_host-build-target] 43 commits: Check that shift values are valid
by Sven Tennie (＠supersven) 28 Mar '26

28 Mar '26

Sven Tennie pushed to branch wip/supersven/correctly_propagate_host-build-target 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 - - - - - 404b71c1 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Fix assert in Interpreter.c If we skip exactly the number of words on the stack we end up on the first word in the next chunk. - - - - - a85bd503 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Support arbitrary size unboxed tuples in bytecode This stores the size (number of words on the stack) of the next expected tuple in the TSO, ctoi_spill_size field, eliminating the need of stg_ctoi_tN frames for each size. Note: On 32 bit platform there is still a bytecode tuple size limit of 255 words on the stack. Fixes #26946 - - - - - e2209031 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Add specialized frames for small tuples Small tuples are now returned more efficiently to the interpreter. They use one less word of stack space and don't need manipulation of the TSO anymore. - - - - - b26bb2ea by VeryMilkyJoe at 2026-03-27T04:41:38-04:00 Remove backwards compatibility pattern synonym `ModLocation` Fixes #24932 - - - - - 66e5e324 by Vladislav Zavialov at 2026-03-27T04:42:25-04:00 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 - - - - - f8de456f by Sylvain Henry at 2026-03-27T04:43:22-04:00 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> - - - - - fcf092dd by Luite Stegeman at 2026-03-27T04:44:17-04:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 - - - - - 05094993 by Luite Stegeman at 2026-03-27T04:45:12-04:00 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 - - - - - 4ee260cf by sheaf at 2026-03-27T04:46:06-04:00 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 - - - - - e97232ce by Hai at 2026-03-27T04:47:04-04:00 Parser.y: avoid looking at token with QualifiedDo This changes the behavior of 'hintQualifiedDo' so that the supplied token is not inspected when the QualifiedDo language extension bit is set. - - - - - 9831385b by Vladislav Zavialov at 2026-03-27T17:22:30-04:00 Infix holes in types (#11107) This patch introduces several improvements that follow naturally from refactoring HsOpTy to represent the operator as an HsType, aligning it with the approach taken by OpApp and HsExpr. User-facing changes: 1. Infix holes (t1 `_` t2) are now permitted in types, following the precedent set by term-level expressions. Test case: T11107 2. Error messages for illegal promotion ticks are now reported at more precise source locations. Test case: T17865 Internal changes: * The definition of HsOpTy now mirrors that of OpApp: | HsOpTy (XOpTy p) (LHsType p) (LHsType p) (LHsType p) | OpApp (XOpApp p) (LHsExpr p) (LHsExpr p) (LHsExpr p) This moves us one step closer to unifying HsType and HsExpr. * Ignoring locations, the old pattern match (HsOpTy x prom lhs op rhs) is now written as (HsOpTy x lhs (HsTyVar x' prom op) rhs) but we also handle (HsOpTy x lhs (HsWildCardTy x') rhs) Constructors other than HsTyVar and HsWildCardTy never appear in the operator position. * The various definitions across the compiler have been updated to work with the new representation, drawing inspiration from the term-level pipeline where appropriate. For example, ppr_infix_ty <=> ppr_infix_expr get_tyop <=> get_op lookupTypeFixityRn <=> lookupExprFixityRn (the latter is factored out from rnExpr) Test cases: T11107 T17865 - - - - - 5b6757d7 by mangoiv at 2026-03-27T17:23:19-04:00 ci: build i386 non-validate for deb12 This is a small fix that will unlock ghcup metadata to run, i386 debian 12 was missing as a job. - - - - - 95dd407b by Matthew Pickering at 2026-03-28T06:41:04+00:00 packaging: correctly propagate build/host/target to bindist configure script At the moment the host and target which we will produce a compiler for is fixed at the initial configure time. Therefore we need to persist the choice made at this time into the installation bindist as well so we look for the right tools, with the right prefixes at install time. In the future, we want to provide a bit more control about what kind of bindist we produce so the logic about what the host/target will have to be written by hadrian rather than persisted by the configure script. In particular with cross compilers we want to either build a normal stage 2 cross bindist or a stage 3 bindist, which creates a bindist which has a native compiler for the target platform. Fixes #21970 Co-authored-by: Sven Tennie <sven.tennie(a)gmail.com> - - - - - 136d30c6 by Sven Tennie at 2026-03-28T06:41:04+00:00 Cross --host and --target no longer required for cross (#21970) We set sane defaults in the configure script. Thus, these paramenters aren't required any longer. - - - - - a0c6c7f7 by Sven Tennie at 2026-03-28T06:41:04+00:00 bindist: Propagate user set $LD to ghc-toolchain Otherwise, ghc-toolchain wrongly emits `-fuse-ld` for cross-compilers. - - - - - 42a6fc34 by Sven Tennie at 2026-03-28T06:41:04+00:00 Respect user set CFLAGS, CXXFLAGS and LDFLAGS These were ignored on installs. - - - - - 1659bbe3 by Sven Tennie at 2026-03-28T06:41:04+00:00 Only add flags if they are new This prevents duplicated when the user already set the arguments in CXXFLAGS or CFLAGS. - - - - - 336386de by Sven Tennie at 2026-03-28T06:41:04+00:00 Revert "Only add flags if they are new" This reverts commit 312deb98d69a80a3b1183188c92bf83c86644021. - - - - - 0024bbbc by Sven Tennie at 2026-03-28T06:41:04+00:00 Prevent -g - - - - - 234 changed files: - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - + .gitlab/issue_templates/release_tracking.md - .gitlab/jobs.yaml - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/GHC.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/ByteCode/Types.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/CoreToStg/AddImplicitBinds.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/Hs/Utils.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 - 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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6c712038468504482327995bbc92fc… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6c712038468504482327995bbc92fc… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/ani/no-ds-flag-cache] 52 commits: Add 128-bit SIMD support to AArch64 NCG
by Apoorv Ingle (＠ani) 28 Mar '26

28 Mar '26

Apoorv Ingle pushed to branch wip/ani/no-ds-flag-cache at Glasgow Haskell Compiler / GHC Commits: 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 - - - - - 404b71c1 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Fix assert in Interpreter.c If we skip exactly the number of words on the stack we end up on the first word in the next chunk. - - - - - a85bd503 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Support arbitrary size unboxed tuples in bytecode This stores the size (number of words on the stack) of the next expected tuple in the TSO, ctoi_spill_size field, eliminating the need of stg_ctoi_tN frames for each size. Note: On 32 bit platform there is still a bytecode tuple size limit of 255 words on the stack. Fixes #26946 - - - - - e2209031 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Add specialized frames for small tuples Small tuples are now returned more efficiently to the interpreter. They use one less word of stack space and don't need manipulation of the TSO anymore. - - - - - b26bb2ea by VeryMilkyJoe at 2026-03-27T04:41:38-04:00 Remove backwards compatibility pattern synonym `ModLocation` Fixes #24932 - - - - - 66e5e324 by Vladislav Zavialov at 2026-03-27T04:42:25-04:00 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 - - - - - f8de456f by Sylvain Henry at 2026-03-27T04:43:22-04:00 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> - - - - - fcf092dd by Luite Stegeman at 2026-03-27T04:44:17-04:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 - - - - - 05094993 by Luite Stegeman at 2026-03-27T04:45:12-04:00 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 - - - - - 4ee260cf by sheaf at 2026-03-27T04:46:06-04:00 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 - - - - - e97232ce by Hai at 2026-03-27T04:47:04-04:00 Parser.y: avoid looking at token with QualifiedDo This changes the behavior of 'hintQualifiedDo' so that the supplied token is not inspected when the QualifiedDo language extension bit is set. - - - - - 9831385b by Vladislav Zavialov at 2026-03-27T17:22:30-04:00 Infix holes in types (#11107) This patch introduces several improvements that follow naturally from refactoring HsOpTy to represent the operator as an HsType, aligning it with the approach taken by OpApp and HsExpr. User-facing changes: 1. Infix holes (t1 `_` t2) are now permitted in types, following the precedent set by term-level expressions. Test case: T11107 2. Error messages for illegal promotion ticks are now reported at more precise source locations. Test case: T17865 Internal changes: * The definition of HsOpTy now mirrors that of OpApp: | HsOpTy (XOpTy p) (LHsType p) (LHsType p) (LHsType p) | OpApp (XOpApp p) (LHsExpr p) (LHsExpr p) (LHsExpr p) This moves us one step closer to unifying HsType and HsExpr. * Ignoring locations, the old pattern match (HsOpTy x prom lhs op rhs) is now written as (HsOpTy x lhs (HsTyVar x' prom op) rhs) but we also handle (HsOpTy x lhs (HsWildCardTy x') rhs) Constructors other than HsTyVar and HsWildCardTy never appear in the operator position. * The various definitions across the compiler have been updated to work with the new representation, drawing inspiration from the term-level pipeline where appropriate. For example, ppr_infix_ty <=> ppr_infix_expr get_tyop <=> get_op lookupTypeFixityRn <=> lookupExprFixityRn (the latter is factored out from rnExpr) Test cases: T11107 T17865 - - - - - 5b6757d7 by mangoiv at 2026-03-27T17:23:19-04:00 ci: build i386 non-validate for deb12 This is a small fix that will unlock ghcup metadata to run, i386 debian 12 was missing as a job. - - - - - 3519a2aa by Apoorv Ingle at 2026-03-28T00:19:34-05:00 Work for #25001 Notes added [Error Context Stack] [Typechecking by expansion: overview] Notes updated Note [Expanding HsDo with XXExprGhcRn] ------------------------- Metric Decrease: T9020 ------------------------- * Streamlines implementations of `tcExpr` and `tcXExpr` to work on `XExpr` * Kills `VACtxt` (and its associated `VAExpansion` and `VACall`) datatype, it is subsumed by simply a `SrcSpan`. * Kills the function `addHeadCtxt` as it is now mearly setting a location * The function `tcValArgs` does its own argument number management * Makes `splitHsApps` not look through `XExpr` * `tcExprSigma` is called if the head of the expression after calling `splitHsApps` turns out to be an `XExpr` * Removes location information from `OrigPat` payload * Removes special case of tcBody from `tcLambdaMatches` * Removes special case of `dsExpr` for `ExpandedThingTc` * Rename `HsThingRn` to `SrcCodeCtxt` * Kills `tcl_in_gen_code` and `tcl_err_ctxt`. It is subsumed by `ErrCtxtStack` * Kills `ExpectedFunTyOrig`. It is subsumed by `CtOrigin` * Fixes `CtOrigin` for `HsProjection` case in `exprCtOrigin`. It was previously assigned to be `SectionOrigin`. It is now just the expression * Adds a new `CtOrigin.ExpansionOrigin` for storing the original syntax * Adds a new `CtOrigin.ExpectedTySyntax` as a replacement for `ExpectedTySyntaxOp`. Cannot kill the former yet because of `ApplicativeDo` * Renames `tcMonoExpr` -> `tcMonoLExpr`, `tcMonoExprNC` -> `tcMonoLExpr` * Renames `EValArg`, `EValArgQL` fields: `ea_ctxt` -> `ea_loc_span` and `eaql_ctx` -> `eaql_loc_span` * kill `PopErrCtxt` from `XXExprGhcRn` * simplify `addArgCtxt` and push `setSrcSpan` inside `addLExprCtxt`. Make sure addExprCtxt is not called by itself * fun_orig in tcApp depends on the SrcSpan of the head of the application chain (similar to addArgCtxt) * rename fun_ctxt to fun_lspan, fun_orig passed in tcInstFun to default to app chain head if its user located, fall back to srcCodeOrigin if it's a generated location * fix quickLookArg function to blame the correct application chain head. The arguments application chain head should be blamed, not the original head when we quick look arg * Make sure only expression wrapped around generated src span are ignored while adding them to the error context stack * `getDeepSubsumptionFlag_DataConHead` performs a non-trivial traversal if the expression passed to it is complex. This traversal is necessary if the head of the function is an `XExpr` and `splitHsApps` does not look through them - The deepsubsumption flag is stored in EVAlArgQL to reduce the need to call `getDeepSubsumptionFlag_DataConHead` - `getDeepSubsumptionFlag_DataConHead` is called in `tcExprSigma` and `tcInferAppHead` to reduce AST traversals * Make a new variant `GeneratedSrcSpan` in `SrcSpan` for HIEAst Nodes * wrap `fromListN` with a generated src span with GeneratedSrcSpanDetails field to store the original srcspan * remove `UnhelpfulGenerated` from `UnhelpfulSpanReason` and into new datatype `GeneratedSrcSpanDetails` * trying to remove SrcCodeOrigin by merging it with ErrCtxtMsg * ErrCtxtMsg is now HsCtxt * Landmarks are now just computed on the fly * killed off CodeSrcFlag - - - - - f0ea55da by Apoorv Ingle at 2026-03-28T00:19:53-05:00 make HsExpandedRn and HsExpandedTc payload LExpr, add tcExpand for expanding Do expressions before typechecking in tcExpr - - - - - af2b60ad by Apoorv Ingle at 2026-03-28T00:19:53-05:00 * make HsExpandedRn and HsExpandedTc payload LExpr, HsExpand to mediate between expansion and typechecking * add tcHsExpand type checking expanded Expressions * remove setInGeneratedCode - - - - - 56ab29d0 by Apoorv Ingle at 2026-03-28T00:19:53-05:00 remove srcCodeOrigin references, add some WIP flag - - - - - a0aa2eff by Apoorv Ingle at 2026-03-28T00:19:53-05:00 accept callstack001 testcase - - - - - aa156aec by Apoorv Ingle at 2026-03-28T00:19:54-05:00 update Note to include HsExpansion - - - - - 034b1fd0 by Simon Peyton Jones at 2026-03-28T00:19:54-05:00 Tidying up from Simon - - - - - 0ba604b0 by Simon Peyton Jones at 2026-03-28T00:19:54-05:00 More from Simon - - - - - e92a8b8b by Apoorv Ingle at 2026-03-28T00:19:54-05:00 remove unused function - - - - - f11627b3 by Apoorv Ingle at 2026-03-28T00:19:54-05:00 account for rebase changes - - - - - 53c0213d by Apoorv Ingle at 2026-03-28T00:19:54-05:00 do not cache ds_flag - - - - - 421f879b by Apoorv Ingle at 2026-03-28T01:09:00-05:00 some comments and review changes - - - - - 773862a5 by Apoorv Ingle at 2026-03-28T01:30:43-05:00 do not recurse in ExpandedThingTc HsApp etc in getDeepSubsumptionFlag - - - - - 348 changed files: - .gitlab/generate-ci/gen_ci.hs - + .gitlab/issue_templates/release_tracking.md - .gitlab/jobs.yaml - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/CodeGen.Platform.h - compiler/GHC.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/ByteCode/Types.hs - compiler/GHC/Cmm/Node.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/Reg/Graph/TrivColorable.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/CoreToStg/AddImplicitBinds.hs - compiler/GHC/Driver/Config/CmmToLlvm.hs - compiler/GHC/Driver/Config/StgToCmm.hs - compiler/GHC/Hs/DocString.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/Expr.hs-boot - compiler/GHC/Hs/Instances.hs - compiler/GHC/Hs/Syn/Type.hs - compiler/GHC/Hs/Type.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Arrows.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Match.hs - compiler/GHC/HsToCore/Monad.hs - compiler/GHC/HsToCore/Pmc.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Iface/Ext/Utils.hs - compiler/GHC/Iface/Type.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/Errors/Types.hs - compiler/GHC/Parser/HaddockLex.x - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Prelude/Basic.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Fixity.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Runtime/Debugger/Breakpoints.hs - compiler/GHC/StgToByteCode.hs - compiler/GHC/StgToCmm/Expr.hs - compiler/GHC/StgToCmm/Utils.hs - compiler/GHC/Tc/Deriv.hs - compiler/GHC/Tc/Deriv/Infer.hs - compiler/GHC/Tc/Deriv/Utils.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - + compiler/GHC/Tc/Gen/App.hs-boot - compiler/GHC/Tc/Gen/Arrow.hs - compiler/GHC/Tc/Gen/Bind.hs - compiler/GHC/Tc/Gen/Do.hs - compiler/GHC/Tc/Gen/Export.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Gen/Expr.hs-boot - compiler/GHC/Tc/Gen/Head.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Gen/Match.hs - compiler/GHC/Tc/Gen/Match.hs-boot - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Gen/Sig.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Instance/Class.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/Solver/Solve.hs - compiler/GHC/Tc/TyCl.hs - compiler/GHC/Tc/TyCl/Class.hs - compiler/GHC/Tc/TyCl/Instance.hs - compiler/GHC/Tc/TyCl/PatSyn.hs - compiler/GHC/Tc/Types.hs - compiler/GHC/Tc/Types/BasicTypes.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/CtLoc.hs - compiler/GHC/Tc/Types/ErrCtxt.hs - compiler/GHC/Tc/Types/LclEnv.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Types/Origin.hs-boot - compiler/GHC/Tc/Utils/Instantiate.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/TcType.hs-boot - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Validity.hs - compiler/GHC/Tc/Zonk/TcType.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Error.hs - + compiler/GHC/Types/Error.hs-boot - compiler/GHC/Types/Hint/Ppr.hs - compiler/GHC/Types/Name/Reader.hs - compiler/GHC/Types/SrcLoc.hs - compiler/GHC/Unit/Module/Location.hs - + compiler/GHC/Unit/State.hs-boot - compiler/GHC/Utils/Binary.hs - compiler/GHC/Utils/Logger.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 - ghc/GHCi/UI.hs - ghc/GHCi/UI/Info.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/Apply.cmm - rts/CloneStack.c - rts/CloneStack.h - rts/Continuation.c - rts/ContinuationOps.cmm - rts/HeapStackCheck.cmm - rts/IOManager.c - rts/Interpreter.c - rts/Messages.c - rts/PrimOps.cmm - rts/Printer.c - rts/RaiseAsync.c - rts/RtsFlags.c - rts/RtsSymbols.c - rts/STM.c - rts/STM.h - rts/Schedule.c - rts/StgCRun.c - rts/StgMiscClosures.cmm - rts/Threads.c - rts/Threads.h - rts/eventlog/EventLog.c - rts/include/rts/Bytecodes.h - rts/include/rts/Constants.h - rts/include/rts/PosixSource.h - rts/include/rts/storage/TSO.h - rts/include/stg/MiscClosures.h - rts/include/stg/Prim.h - rts/prim/vectorQuotRem.c - rts/win32/AsyncMIO.c - rts/win32/AsyncMIO.h - + testsuite/tests/bytecode/tuplestress/ByteCode.hs - + testsuite/tests/bytecode/tuplestress/Common.hs-incl - + testsuite/tests/bytecode/tuplestress/Obj.hs - + testsuite/tests/bytecode/tuplestress/TupleStress.hs - + testsuite/tests/bytecode/tuplestress/TupleStress.stdout - + testsuite/tests/bytecode/tuplestress/all.T - 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/concurrent/should_run/T26341.hs - + testsuite/tests/concurrent/should_run/T26341.stdout - + testsuite/tests/concurrent/should_run/T26341a.hs - + testsuite/tests/concurrent/should_run/T26341a.stdout - + testsuite/tests/concurrent/should_run/T26341b.hs - + testsuite/tests/concurrent/should_run/T26341b.stdout - testsuite/tests/concurrent/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/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/ghc-api/fixed-nodes/FixedNodes.hs - testsuite/tests/ghc-api/fixed-nodes/ModuleGraphInvariants.hs - testsuite/tests/ghci/prog-mhu001/prog-mhu001c.stdout - testsuite/tests/ghci/scripts/ListTuplePunsPpr.stdout - testsuite/tests/ghci/scripts/T10963.stderr - testsuite/tests/ghci/scripts/ghci064.stdout - testsuite/tests/indexed-types/should_fail/T2693.stderr - 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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/80dbb0976dc16148d214575225f4a5… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/80dbb0976dc16148d214575225f4a5… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/spj-apporv-Oct24] 51 commits: Add 128-bit SIMD support to AArch64 NCG
by Apoorv Ingle (＠ani) 28 Mar '26

28 Mar '26

Apoorv Ingle pushed to branch wip/spj-apporv-Oct24 at Glasgow Haskell Compiler / GHC Commits: 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 - - - - - 404b71c1 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Fix assert in Interpreter.c If we skip exactly the number of words on the stack we end up on the first word in the next chunk. - - - - - a85bd503 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Support arbitrary size unboxed tuples in bytecode This stores the size (number of words on the stack) of the next expected tuple in the TSO, ctoi_spill_size field, eliminating the need of stg_ctoi_tN frames for each size. Note: On 32 bit platform there is still a bytecode tuple size limit of 255 words on the stack. Fixes #26946 - - - - - e2209031 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Add specialized frames for small tuples Small tuples are now returned more efficiently to the interpreter. They use one less word of stack space and don't need manipulation of the TSO anymore. - - - - - b26bb2ea by VeryMilkyJoe at 2026-03-27T04:41:38-04:00 Remove backwards compatibility pattern synonym `ModLocation` Fixes #24932 - - - - - 66e5e324 by Vladislav Zavialov at 2026-03-27T04:42:25-04:00 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 - - - - - f8de456f by Sylvain Henry at 2026-03-27T04:43:22-04:00 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> - - - - - fcf092dd by Luite Stegeman at 2026-03-27T04:44:17-04:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 - - - - - 05094993 by Luite Stegeman at 2026-03-27T04:45:12-04:00 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 - - - - - 4ee260cf by sheaf at 2026-03-27T04:46:06-04:00 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 - - - - - e97232ce by Hai at 2026-03-27T04:47:04-04:00 Parser.y: avoid looking at token with QualifiedDo This changes the behavior of 'hintQualifiedDo' so that the supplied token is not inspected when the QualifiedDo language extension bit is set. - - - - - 9831385b by Vladislav Zavialov at 2026-03-27T17:22:30-04:00 Infix holes in types (#11107) This patch introduces several improvements that follow naturally from refactoring HsOpTy to represent the operator as an HsType, aligning it with the approach taken by OpApp and HsExpr. User-facing changes: 1. Infix holes (t1 `_` t2) are now permitted in types, following the precedent set by term-level expressions. Test case: T11107 2. Error messages for illegal promotion ticks are now reported at more precise source locations. Test case: T17865 Internal changes: * The definition of HsOpTy now mirrors that of OpApp: | HsOpTy (XOpTy p) (LHsType p) (LHsType p) (LHsType p) | OpApp (XOpApp p) (LHsExpr p) (LHsExpr p) (LHsExpr p) This moves us one step closer to unifying HsType and HsExpr. * Ignoring locations, the old pattern match (HsOpTy x prom lhs op rhs) is now written as (HsOpTy x lhs (HsTyVar x' prom op) rhs) but we also handle (HsOpTy x lhs (HsWildCardTy x') rhs) Constructors other than HsTyVar and HsWildCardTy never appear in the operator position. * The various definitions across the compiler have been updated to work with the new representation, drawing inspiration from the term-level pipeline where appropriate. For example, ppr_infix_ty <=> ppr_infix_expr get_tyop <=> get_op lookupTypeFixityRn <=> lookupExprFixityRn (the latter is factored out from rnExpr) Test cases: T11107 T17865 - - - - - 5b6757d7 by mangoiv at 2026-03-27T17:23:19-04:00 ci: build i386 non-validate for deb12 This is a small fix that will unlock ghcup metadata to run, i386 debian 12 was missing as a job. - - - - - 3519a2aa by Apoorv Ingle at 2026-03-28T00:19:34-05:00 Work for #25001 Notes added [Error Context Stack] [Typechecking by expansion: overview] Notes updated Note [Expanding HsDo with XXExprGhcRn] ------------------------- Metric Decrease: T9020 ------------------------- * Streamlines implementations of `tcExpr` and `tcXExpr` to work on `XExpr` * Kills `VACtxt` (and its associated `VAExpansion` and `VACall`) datatype, it is subsumed by simply a `SrcSpan`. * Kills the function `addHeadCtxt` as it is now mearly setting a location * The function `tcValArgs` does its own argument number management * Makes `splitHsApps` not look through `XExpr` * `tcExprSigma` is called if the head of the expression after calling `splitHsApps` turns out to be an `XExpr` * Removes location information from `OrigPat` payload * Removes special case of tcBody from `tcLambdaMatches` * Removes special case of `dsExpr` for `ExpandedThingTc` * Rename `HsThingRn` to `SrcCodeCtxt` * Kills `tcl_in_gen_code` and `tcl_err_ctxt`. It is subsumed by `ErrCtxtStack` * Kills `ExpectedFunTyOrig`. It is subsumed by `CtOrigin` * Fixes `CtOrigin` for `HsProjection` case in `exprCtOrigin`. It was previously assigned to be `SectionOrigin`. It is now just the expression * Adds a new `CtOrigin.ExpansionOrigin` for storing the original syntax * Adds a new `CtOrigin.ExpectedTySyntax` as a replacement for `ExpectedTySyntaxOp`. Cannot kill the former yet because of `ApplicativeDo` * Renames `tcMonoExpr` -> `tcMonoLExpr`, `tcMonoExprNC` -> `tcMonoLExpr` * Renames `EValArg`, `EValArgQL` fields: `ea_ctxt` -> `ea_loc_span` and `eaql_ctx` -> `eaql_loc_span` * kill `PopErrCtxt` from `XXExprGhcRn` * simplify `addArgCtxt` and push `setSrcSpan` inside `addLExprCtxt`. Make sure addExprCtxt is not called by itself * fun_orig in tcApp depends on the SrcSpan of the head of the application chain (similar to addArgCtxt) * rename fun_ctxt to fun_lspan, fun_orig passed in tcInstFun to default to app chain head if its user located, fall back to srcCodeOrigin if it's a generated location * fix quickLookArg function to blame the correct application chain head. The arguments application chain head should be blamed, not the original head when we quick look arg * Make sure only expression wrapped around generated src span are ignored while adding them to the error context stack * `getDeepSubsumptionFlag_DataConHead` performs a non-trivial traversal if the expression passed to it is complex. This traversal is necessary if the head of the function is an `XExpr` and `splitHsApps` does not look through them - The deepsubsumption flag is stored in EVAlArgQL to reduce the need to call `getDeepSubsumptionFlag_DataConHead` - `getDeepSubsumptionFlag_DataConHead` is called in `tcExprSigma` and `tcInferAppHead` to reduce AST traversals * Make a new variant `GeneratedSrcSpan` in `SrcSpan` for HIEAst Nodes * wrap `fromListN` with a generated src span with GeneratedSrcSpanDetails field to store the original srcspan * remove `UnhelpfulGenerated` from `UnhelpfulSpanReason` and into new datatype `GeneratedSrcSpanDetails` * trying to remove SrcCodeOrigin by merging it with ErrCtxtMsg * ErrCtxtMsg is now HsCtxt * Landmarks are now just computed on the fly * killed off CodeSrcFlag - - - - - f0ea55da by Apoorv Ingle at 2026-03-28T00:19:53-05:00 make HsExpandedRn and HsExpandedTc payload LExpr, add tcExpand for expanding Do expressions before typechecking in tcExpr - - - - - af2b60ad by Apoorv Ingle at 2026-03-28T00:19:53-05:00 * make HsExpandedRn and HsExpandedTc payload LExpr, HsExpand to mediate between expansion and typechecking * add tcHsExpand type checking expanded Expressions * remove setInGeneratedCode - - - - - 56ab29d0 by Apoorv Ingle at 2026-03-28T00:19:53-05:00 remove srcCodeOrigin references, add some WIP flag - - - - - a0aa2eff by Apoorv Ingle at 2026-03-28T00:19:53-05:00 accept callstack001 testcase - - - - - aa156aec by Apoorv Ingle at 2026-03-28T00:19:54-05:00 update Note to include HsExpansion - - - - - 034b1fd0 by Simon Peyton Jones at 2026-03-28T00:19:54-05:00 Tidying up from Simon - - - - - 0ba604b0 by Simon Peyton Jones at 2026-03-28T00:19:54-05:00 More from Simon - - - - - e92a8b8b by Apoorv Ingle at 2026-03-28T00:19:54-05:00 remove unused function - - - - - f11627b3 by Apoorv Ingle at 2026-03-28T00:19:54-05:00 account for rebase changes - - - - - 53c0213d by Apoorv Ingle at 2026-03-28T00:19:54-05:00 do not cache ds_flag - - - - - 421f879b by Apoorv Ingle at 2026-03-28T01:09:00-05:00 some comments and review changes - - - - - 348 changed files: - .gitlab/generate-ci/gen_ci.hs - + .gitlab/issue_templates/release_tracking.md - .gitlab/jobs.yaml - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - 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utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.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/Backends/Xhtml/Utils.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/GhcUtils.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/12945b324b5c15f9d671094ac51d36… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/12945b324b5c15f9d671094ac51d36… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/sjakobi/T27097] Eliminate dictionary-passing in ListMap operations
by Simon Jakobi (＠sjakobi2) 28 Mar '26

28 Mar '26

Simon Jakobi pushed to branch wip/sjakobi/T27097 at Glasgow Haskell Compiler / GHC Commits: 698924cc by Simon Jakobi at 2026-03-28T03:21:27+01:00 Eliminate dictionary-passing in ListMap operations Mark the ListMap helpers 'INLINABLE' so importing modules can specialise the 'TrieMap (ListMap m)' methods and avoid recursive dictionary-passing. See Note [Making ListMap operations specialisable]. Fixes #27097 - - - - - 1 changed file: - compiler/GHC/Data/TrieMap.hs Changes: ===================================== compiler/GHC/Data/TrieMap.hs ===================================== @@ -327,28 +327,60 @@ instance TrieMap m => Foldable (ListMap m) where instance (TrieMap m, Outputable a) => Outputable (ListMap m a) where ppr m = text "List elts" <+> ppr (foldTM (:) m []) +{- Note [Making ListMap operations specialisable] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The 'TrieMap (ListMap m)' methods are thin wrappers around these helpers: + + lookupTM = lkList lookupTM + alterTM = xtList alterTM + foldTM = fdList + filterTM = ftList + mapMaybeTM = mpList + +When these methods are used from another module, the wrappers would otherwise +remain higher-order and polymorphic in the inner trie map. That leaves the +recursive loops in 'xtList', 'fdList', 'ftList', and 'mpList' calling the +inner-map operations indirectly via the 'TrieMap m' dictionary (#27097). + +Marking the helpers 'INLINABLE' exposes unfoldings to importing modules, so +the specialiser can monomorphise those loops; see Note [Specialising imported +functions] in GHC.Core.Opt.Specialise. + +Adding the 'INLINABLE' pragmas reduced compiler allocations by 2.9% in +InstanceMatching and by 2.0% in T24984. + +We mark 'lkList' too, even though it does not itself use the 'TrieMap m' +dictionary and GHC already gives it a non-dictionary-passing worker, for +consistency with the other ListMap operations. +-} + lkList :: TrieMap m => (forall b. k -> m b -> Maybe b) -> [k] -> ListMap m a -> Maybe a lkList _ [] = lm_nil lkList lk (x:xs) = lm_cons >.> lk x >=> lkList lk xs +{-# INLINABLE lkList #-} -- See Note [Making ListMap operations specialisable] xtList :: TrieMap m => (forall b. k -> XT b -> m b -> m b) -> [k] -> XT a -> ListMap m a -> ListMap m a xtList _ [] f m = m { lm_nil = f (lm_nil m) } xtList tr (x:xs) f m = m { lm_cons = lm_cons m |> tr x |>> xtList tr xs f } +{-# INLINABLE xtList #-} -- See Note [Making ListMap operations specialisable] fdList :: forall m a b. TrieMap m => (a -> b -> b) -> ListMap m a -> b -> b fdList k m = foldMaybe k (lm_nil m) . foldTM (fdList k) (lm_cons m) +{-# INLINABLE fdList #-} -- See Note [Making ListMap operations specialisable] ftList :: TrieMap m => (a -> Bool) -> ListMap m a -> ListMap m a ftList f (LM { lm_nil = mnil, lm_cons = mcons }) = LM { lm_nil = filterMaybe f mnil, lm_cons = fmap (filterTM f) mcons } +{-# INLINABLE ftList #-} -- See Note [Making ListMap operations specialisable] mpList :: TrieMap m => (a -> Maybe b) -> ListMap m a -> ListMap m b mpList f (LM { lm_nil = mnil, lm_cons = mcons }) = LM { lm_nil = mnil >>= f, lm_cons = fmap (mapMaybeTM f) mcons } +{-# INLINABLE mpList #-} -- See Note [Making ListMap operations specialisable] {- ************************************************************************ View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/698924ccfdeefce59a1830f61e95632… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/698924ccfdeefce59a1830f61e95632… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/sjakobi/T27097] 37 commits: Check that shift values are valid
by Simon Jakobi (＠sjakobi2) 28 Mar '26

28 Mar '26

Simon Jakobi pushed to branch wip/sjakobi/T27097 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 - - - - - 404b71c1 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Fix assert in Interpreter.c If we skip exactly the number of words on the stack we end up on the first word in the next chunk. - - - - - a85bd503 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Support arbitrary size unboxed tuples in bytecode This stores the size (number of words on the stack) of the next expected tuple in the TSO, ctoi_spill_size field, eliminating the need of stg_ctoi_tN frames for each size. Note: On 32 bit platform there is still a bytecode tuple size limit of 255 words on the stack. Fixes #26946 - - - - - e2209031 by Luite Stegeman at 2026-03-27T04:40:49-04:00 Add specialized frames for small tuples Small tuples are now returned more efficiently to the interpreter. They use one less word of stack space and don't need manipulation of the TSO anymore. - - - - - b26bb2ea by VeryMilkyJoe at 2026-03-27T04:41:38-04:00 Remove backwards compatibility pattern synonym `ModLocation` Fixes #24932 - - - - - 66e5e324 by Vladislav Zavialov at 2026-03-27T04:42:25-04:00 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 - - - - - f8de456f by Sylvain Henry at 2026-03-27T04:43:22-04:00 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> - - - - - fcf092dd by Luite Stegeman at 2026-03-27T04:44:17-04:00 Windows: remove StgAsyncIOResult and fix crash/leaks In stg_block_async{_void}, a stack slot was reserved for an StgAsyncIOResult. This slot would be filled by the IO manager upon completion of the async call. However, if the blocked thread was interrupted by an async exception, we would end up in an invalid state: - If the blocked computation was never re-entered, the StgAsyncIOResult would never be freed. - If the blocked computation was re-entered, the thread would find an unitialized stack slot for the StgAsyncIOResult, leading to a crash reading its fields, or freeing the pointer. We fix this by removing the StgAsyncIOResult altogether and writing the result directly to the stack. Fixes #26341 - - - - - 05094993 by Luite Stegeman at 2026-03-27T04:45:12-04:00 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 - - - - - 4ee260cf by sheaf at 2026-03-27T04:46:06-04:00 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 - - - - - e97232ce by Hai at 2026-03-27T04:47:04-04:00 Parser.y: avoid looking at token with QualifiedDo This changes the behavior of 'hintQualifiedDo' so that the supplied token is not inspected when the QualifiedDo language extension bit is set. - - - - - 9831385b by Vladislav Zavialov at 2026-03-27T17:22:30-04:00 Infix holes in types (#11107) This patch introduces several improvements that follow naturally from refactoring HsOpTy to represent the operator as an HsType, aligning it with the approach taken by OpApp and HsExpr. User-facing changes: 1. Infix holes (t1 `_` t2) are now permitted in types, following the precedent set by term-level expressions. Test case: T11107 2. Error messages for illegal promotion ticks are now reported at more precise source locations. Test case: T17865 Internal changes: * The definition of HsOpTy now mirrors that of OpApp: | HsOpTy (XOpTy p) (LHsType p) (LHsType p) (LHsType p) | OpApp (XOpApp p) (LHsExpr p) (LHsExpr p) (LHsExpr p) This moves us one step closer to unifying HsType and HsExpr. * Ignoring locations, the old pattern match (HsOpTy x prom lhs op rhs) is now written as (HsOpTy x lhs (HsTyVar x' prom op) rhs) but we also handle (HsOpTy x lhs (HsWildCardTy x') rhs) Constructors other than HsTyVar and HsWildCardTy never appear in the operator position. * The various definitions across the compiler have been updated to work with the new representation, drawing inspiration from the term-level pipeline where appropriate. For example, ppr_infix_ty <=> ppr_infix_expr get_tyop <=> get_op lookupTypeFixityRn <=> lookupExprFixityRn (the latter is factored out from rnExpr) Test cases: T11107 T17865 - - - - - 5b6757d7 by mangoiv at 2026-03-27T17:23:19-04:00 ci: build i386 non-validate for deb12 This is a small fix that will unlock ghcup metadata to run, i386 debian 12 was missing as a job. - - - - - 5232e718 by Simon Jakobi at 2026-03-28T03:16:32+01:00 Eliminate dictionary-passing in ListMap operations ...by marking them INLINABLE to allow specialization. The INLINABLE for lkList is added for consistency as GHC already generates a non-dictionary-passing worker function. Closes #27097. - - - - - 226 changed files: - .gitlab/generate-ci/gen_ci.hs - + .gitlab/issue_templates/release_tracking.md - .gitlab/jobs.yaml - .gitlab/rel_eng/mk-ghcup-metadata/mk_ghcup_metadata.py - compiler/GHC.hs - compiler/GHC/ByteCode/Asm.hs - compiler/GHC/ByteCode/Instr.hs - compiler/GHC/ByteCode/Linker.hs - compiler/GHC/ByteCode/Serialize.hs - compiler/GHC/ByteCode/Types.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/CoreToStg/AddImplicitBinds.hs - compiler/GHC/Data/TrieMap.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/Hs/Utils.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/Fixity.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/StgToByteCode.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/Gen/Pat.hs - compiler/GHC/Tc/Gen/Sig.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Unit/Module/Location.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 - 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+ testsuite/tests/vdq-rta/should_compile/T26967_tyop.stderr - testsuite/tests/vdq-rta/should_compile/all.T - utils/check-exact/ExactPrint.hs - utils/deriveConstants/Main.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.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/Convert.hs - utils/haddock/haddock-api/src/Haddock/GhcUtils.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/b97b611f7d12d91b698b7a142dfde5… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b97b611f7d12d91b698b7a142dfde5… You're receiving this email because of your account on gitlab.haskell.org.

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