Duncan Coutts pushed to branch wip/dcoutts/issue-27105-stopTicker-2 at Glasgow Haskell Compiler / GHC Commits: f2f5c6ba by Nikita Efremov at 2026-06-02T16:04:54+00:00 fix typo : compete with performance, not complete - - - - - 5524ea0e by Wolfgang Jeltsch at 2026-06-03T08:01:26-04:00 Make the current `base` buildable with GHC 9.14 This comprises the following changes: * Disable some imports into `GHC.Base` for GHC 9.14 * Disable some imports into `Prelude` for GHC 9.14 * Disable separate `ArrowLoop` import for GHC 9.14 * Disable `GHC.Internal.STM` import for GHC 9.14 * Disable `GHC.Internal.Unicode.Version` import for GHC 9.14 * Disable `GHC.Internal.TH.Monad` import for GHC 9.14 * Add alternative `fixIO` import for GHC 9.14 * Add alternative `unsafeCodeCoerce` import for GHC 9.14 * Disable hiding of imported SIMD operations for GHC 9.14 * Disable use of GHC 9.14’s `printToHandleFinalizerExceptionHandler` * Enable use of `getFileHash` from `ghc-internal` for GHC 9.14 * Make `thenA` available for GHC 9.14 * Make `thenM` available for GHC 9.14 * Disable translation of `IoManagerFlagPoll` for GHC 9.14 * Add `hGetNewlineMode` for GHC 9.14 - - - - - d3438055 by Enrico Maria De Angelis at 2026-06-03T08:02:17-04:00 Fix #27067 - Clarify haddocks on `minusNaturalMaybe` - - - - - f9bcfac2 by sheaf at 2026-06-03T14:47:19-04:00 Avoid mkTick in Core Prep breaking ANF As discovered in #27182, mkTick can break ANF. This patch introduces a variant of mkTick that skips the single optimisation that could break ANF. This is preferrable over switching to the raw Tick constructor, as the latter may introduce spurious cost centres in profiling reports. This is a temporary measure until we more thoroughly refactor how mkTick works (see #27141). See Note [mkTick breaks ANF] in GHC.CoreToStg.Prep. Fixes #27182 - - - - - cf1fd661 by Artem Pelenitsyn at 2026-06-03T14:48:09-04:00 clarify comment for getSizeofMutableByteArray#: we get the size in bytes, not "elements" - - - - - a3b431f3 by David Eichmann at 2026-06-04T10:10:19+00:00 Hadrian: convert env variable ACLOCAL_PATH to unix paths. Convert ACLOCAL_PATH to a unix style path when invoking autoreconf. Autoreconf doesn't handle windows paths. See Note [Autoreconf unix paths from ACLOCAL_PATH]. Fixes #27311 - - - - - 18f6138a by Simon Jakobi at 2026-06-04T20:20:31-04:00 testsuite: Deduplicate --only test names config.only is assumed to be a set, but supplying --only overwrote it with the (list) argparse result, which can contain duplicates. When a test ran, config.only.remove(name) dropped only the first occurrence, so a duplicated name lingered and was later misreported as a "test not found" framework failure. Store it as a set instead. Fixes #27322 Co-Authored-By: Claude Opus 4.7 - - - - - 2f3cc9ff by Simon Jakobi at 2026-06-08T07:55:49-04:00 testsuite: detect fast bignum via ghc-internal, not removed ghc-bignum The ghc-bignum package was merged into ghc-internal, so the BIGNUM_GMP probe in test.mk ran `ghc-pkg field ghc-bignum exposed-modules`, which fails with "cannot find package ghc-bignum". That error went to stderr and leaked into the captured stderr of every makefile_test, causing spurious [bad stderr] failures across the suite. The probe also silently returned empty, so config.have_fast_bignum was wrongly False even on GMP builds. Probe ghc-internal's extra-libraries for the gmp library instead: the GMP backend module is an other-module (not exposed), but GMP_LIBS adds gmp to extra-libraries only on a GMP build, so this distinguishes the backends. Redirect stderr to keep any future missing-package error off the harness's stderr. This also removes a stale comment as per suggestion from hsyl20. Co-Authored-By: Claude Opus 4.7 - - - - - eb3bf6e7 by Alan Zimmerman at 2026-06-08T07:56:32-04:00 EPA: Rename Transform.anchorEof to addModuleCommentOrigDeltas This now matches what it actually does. - - - - - 498bb21a by David Eichmann at 2026-06-09T18:02:39-04:00 Hadrian: avoid response files when command line is short enough This replaces the logic of always using response files on Windows. With the new condition based on command line lenght, reponse files can be avoided in many more cases (on windows). Now that response files are only used in a small number of cases, response files are always kept and the -r / --keep-response-files command line options have been removed The response file paths are nolonger randomized. They are placed in the `_build/rsp` directory. This ensures they are ignored by git and we that Hadrian reuses response file paths when rebuilding rather than leaving stale response files around. Update user guide putting response files in its own section - - - - - 87f510a5 by Simon Hengel at 2026-06-09T18:03:25-04:00 Don't use non-breaking spaces - - - - - 41a19379 by David Eichmann at 2026-06-09T18:04:11-04:00 Hadrian: remove unused wrapper scripts from windows bindist These wrapper scripts are only installed on non-relocatable builds which are not generally supported on windows. - - - - - ce01ccb6 by sheaf at 2026-06-10T05:08:48-04:00 Don't drop ticks around variables of type `IO ()` GHC.Core.Utils.mkTick is responsible for placing a tick on a Core expression. It contains logic for dropping SCCs (non-counting profiling ticks) around non-function variables, as such variables cannot meaningfully contribute to profiles. However, the logic for what counts as a function was incorrect: it used `isFunTy` which returns 'False' for types such as 'IO ()' where the function arrow is hidden under a newtype. We now use 'mightBeFunTy' instead of 'isFunTy'. This ensures we don't drop ticks in cases we aren't sure. On the way, we improve the documentation of 'isFunTy', 'isPiTy' and 'mightBeFunTy', and update the latter's implementation to consistently handle unary classes. Fixes #27225 ------------------------- Metric Decrease: T5642 ------------------------- - - - - - d311c4f1 by Simon Jakobi at 2026-06-10T05:09:32-04:00 testsuite: Add regression test for #4081 Check that a strict constructor field is unboxed once outside an enclosing loop, not re-inspected each iteration (the float-out case-floating from 9cb20b488). Uses simonpj's `data T a = T !a` example from the ticket; T4081.stderr captures the expected Core. Co-Authored-By: Claude Opus 4.7 - - - - - 333df444 by sheaf at 2026-06-10T05:10:25-04:00 Check for cabal-install >= 3.12 upfront Starting with commit 8cb99552f607f6bc4000e45ab32532d50c8bb996, Hadrian requires cabal-install >= 3.12 in order to use the 'cabal path' command that was introduced in version 3.12, as per https://github.com/haskell/cabal/blob/a51c4ee1556d816ad86e90db7e6330dd51b0b6... This was not reflected in the Hadrian build script, causing a delayed build failure instead of enforcing the version requirement upfront, which this patch does. Fixes #27317 - - - - - 98c20394 by sheaf at 2026-06-10T05:11:09-04:00 Fix crash in Data.Data instance for HsCtxt The Data.Data instance for HsCtxt contained an error for the 'toConstr' method, which could trigger for example when looking at -ddump-tc-ast traces. Replace it with the 'abstractConstr' pattern used in the rest of the codebase. - - - - - 125b6dcc by Duncan Coutts at 2026-06-10T14:11:12+00:00 Promote HAVE_PREEMPTION from Timer.c to OSThreads.h We will want to know about HAVE_PREEMPTION in more places. HAVE_PREEMPTION tells us that we do have OS threads available, irrespective of whether THREADED is defined. In particular, HAVE_PREEMPTION is defined on all proper OSs, but not on WASM (and hyopthetically may not be true on some other platforms like micro-controllers, RTOSs, VM hypervisors etc). - - - - - a7676f21 by Duncan Coutts at 2026-06-10T14:11:12+00:00 Define ACQUIRE_LOCK_ALWAYS and friends Fix issue #27335 Like the atomic _ALWAYS variants, these lock actions are always defined, rather than being dependent on whether we are in the THREADED case. All the "normal" LOCK macros are defined to be no-ops when !THREADED. The use case for the _ALWAYS variants is where we are using OS threads even in the non-threaded RTS. This includes everything to do with the timer/ticker thread, which is used in the non-threaded RTS too. In particular, we will want to use this for eventlog things, because the timer thread performs eventlogging concurrently with the main capability, even in the non-threaded RTS. - - - - - f843463d by Duncan Coutts at 2026-06-10T14:11:12+00:00 Use ACQUIRE/RELEASE_LOCK_ALWAYS with eventBufMutex Even in the non-threaded RTS the eventBufMutex is needed by both the main capability and the timer/ticker thread, so always use the mutex. This should fix #25165 which is about the main capability and the timer thread posting events to the eventlog buffer concurrently and thereby corrupting the buffer data. - - - - - 88a5acd0 by Duncan Coutts at 2026-06-10T14:11:12+00:00 Expose eventBufMutex in the EventLog interface/header We will need it in forkProcess to ensure we don't write to the global eventlog buffer concurrently with trying to flush eventlog buffers and do the fork(). - - - - - 57e6b753 by Duncan Coutts at 2026-06-10T14:11:12+00:00 Split flushAllCapsEventsBufs into safe and unlocked version Following the convention that unlocked versions have a trailing _ underscore in their name. This one requires the caller to hold the eventlog global buffer mutex. We will need this in forkProcess. - - - - - c8654c4e by Duncan Coutts at 2026-06-10T14:11:12+00:00 Remove redundant use of stopTimer in setNumCapabilities Historically, the comment here was: We must stop the interval timer while we are changing the capabilities array lest handle_tick may try to context switch an old capability. See #17289. and We must disable the timer while we do this since the tick handler may call contextSwitchAllCapabilities, which may see the capabilities array as we free it. What this refers to is that historically, when changing the number of capabilities, the array of capabilities was reallocated to a new size, allocating new ones and freeing the old ones, thus invalidating all existing capbility pointers. Strangely, for good measure the code used to call stopTimer twice (hence the two similar comments above). However, since commit a3eccf06292dd666b24606251a52da2b466a9612, the capabilities array is no longer reallocated. Instead the array is allcoated once on RTS startup to the maximum size it could ever be allowed to be, and then capabilities get enabled/disabled at runtime. So the capability pointers never become invalid anymore. At worst, they may point to capabilities that are disabled. Thus we no longer need to stop the timer (twice) while we change the number of enabled capabilities. This also partially solves issue #27105, which notes that stopTimer is being used as if it were synchronous, when it is not. At least for this case, the solution is that stopTimer is not needed at all! - - - - - 2de7ec63 by Duncan Coutts at 2026-06-10T14:11:12+00:00 Remove redundant use of stopTimer in forkProcess but replace it with taking the eventlog buffer lock during the fork. Fixes issue #27105 The original reason to block the timer during a fork was that historically the timer was implemented using a periodic timer signal, and the signal itself would interrupt the fork system call (returning EINTR). For large processes (where fork() takes a while) this could permanently livelock: the timer always would go off before the fork could complete, which got retried in a loop forever. The timer is no longer implemented as a unix signal, but uses threads. Thus the original problem no longer exists. The only remaining reason to block the timer tick is to prevent actions taken by the tick from interfering with the delicate process involved in fork (taking a load of locks and pausing everything). The only thing we need to do is to prevent the eventlog from being written to or flushed while the fork is taking place. To achieve this all we need to do is hold the mutex for the global eventlog buffer. This removes the last use of stopTimer that expects stopTimer to work synchronously (which it was not) and thus solves issue #27105. To be clear, we solve issue #27105 not by making stopTimer synchronous, but by eliminating the use sites that expected it to be synchronous. - - - - - 72 changed files: - boot - + changelog.d/T27182.md - + changelog.d/T27225 - + changelog.d/T27317 - + changelog.d/T27359 - changelog.d/hadrian-response-files.md - compiler/GHC/Builtin/primops.txt.pp - compiler/GHC/Core/Type.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/CoreToStg/Prep.hs - compiler/GHC/Driver/Backend.hs - compiler/GHC/Hs/Instances.hs - compiler/GHC/Parser/PostProcess/Haddock.hs - compiler/GHC/Runtime/Debugger/Breakpoints.hs - compiler/GHC/Runtime/Eval/Types.hs - compiler/GHC/Runtime/Heap/Inspect.hs - compiler/GHC/Types/RepType.hs - compiler/GHC/Utils/Logger.hs - docs/users_guide/javascript.rst - docs/users_guide/using.rst - hadrian/build-cabal - hadrian/src/Builder.hs - hadrian/src/CommandLine.hs - hadrian/src/Hadrian/Builder/Ar.hs - hadrian/src/Hadrian/Oracles/Path.hs - hadrian/src/Hadrian/Utilities.hs - hadrian/src/Rules/BinaryDist.hs - libraries/base/src/Control/Applicative.hs - libraries/base/src/Control/Arrow.hs - libraries/base/src/Control/Monad.hs - libraries/base/src/Data/Array/Byte.hs - libraries/base/src/Data/Fixed.hs - libraries/base/src/GHC/Base.hs - libraries/base/src/GHC/Conc.hs - libraries/base/src/GHC/Conc/Sync.hs - libraries/base/src/GHC/Exts.hs - libraries/base/src/GHC/Fingerprint.hs - libraries/base/src/GHC/IO/Handle.hs - libraries/base/src/GHC/RTS/Flags.hs - libraries/base/src/GHC/Unicode.hs - libraries/base/src/GHC/Weak.hs - libraries/base/src/GHC/Weak/Finalize.hs - libraries/base/src/Prelude.hs - libraries/base/src/System/IO.hs - libraries/base/src/System/Mem/Weak.hs - libraries/ghc-internal/src/GHC/Internal/Lexeme.hs - libraries/ghc-internal/src/GHC/Internal/Natural.hs - rts/Capability.c - rts/Schedule.c - rts/Timer.c - rts/eventlog/EventLog.c - rts/eventlog/EventLog.h - rts/include/rts/OSThreads.h - testsuite/driver/runtests.py - testsuite/mk/test.mk - testsuite/tests/count-deps/CountDepsAst.stdout - testsuite/tests/count-deps/CountDepsParser.stdout - + testsuite/tests/profiling/should_compile/T27182.hs - testsuite/tests/profiling/should_compile/all.T - + testsuite/tests/profiling/should_run/T27225.hs - + testsuite/tests/profiling/should_run/T27225.stdout - + testsuite/tests/profiling/should_run/T27225b.hs - + testsuite/tests/profiling/should_run/T27225b.stdout - testsuite/tests/profiling/should_run/all.T - testsuite/tests/profiling/should_run/caller-cc/CallerCc1.prof.sample - testsuite/tests/profiling/should_run/callstack001.stdout - testsuite/tests/profiling/should_run/scc001.prof.sample - + testsuite/tests/simplCore/should_compile/T4081.hs - + testsuite/tests/simplCore/should_compile/T4081.stderr - testsuite/tests/simplCore/should_compile/all.T - utils/check-exact/Main.hs - utils/check-exact/Transform.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/55c052e21d93dc427d55a64c11e8a71... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/55c052e21d93dc427d55a64c11e8a71... You're receiving this email because of your account on gitlab.haskell.org.