Duncan Coutts pushed to branch wip/dcoutts/io-manager-tidy at Glasgow Haskell Compiler / GHC

Commits:

• c6d53c16
  by sheaf at 2026-07-02T21:35:44-04:00

  Test driver: normalise line numbers into libraries
  
  When comparing the stdout of tests that print out callstacks, we can't
  rely on the stability of exact line:column spans pointing into libraries
  (e.g. ghc-internal), as any change (such as adding a comment) can change
  them.
  
  This commit addresses this by normalising away line:column in callstacks,
  but only when those point into internal libraries. We don't do this in
  general, as the exact span might be important to the test (e.g. for a
  span within the test module itself).
  
  Fixes #27387
  

• 81ee62e0
  by Alan Zimmerman at 2026-07-02T21:36:33-04:00

  EPA: Remove LocatedLW from MatchGroup
  
  This is the last usage of LocatedLW / SrcSpanAnnLW
  

• 925959db
  by Recursion Ninja at 2026-07-04T04:14:12-04:00

  Decoupling 'L.H.S' from 'GHC.Hs.Doc'
  
    * Migrated 'GHC.Hs.Doc' and 'GHC.Hs.DocString' AST defintions from 'GHC.*' namespace,
      to new 'Language.Haskell.Syntax.Doc' module in the 'L.H.S' "namespace."
    * Updated 'HsDocString to be TTG-parameterised as 'HsDocString pass'.
    * Added 'GHC.Hs.Extension.Pass': splits 'GhcPass'/'Pass' and all 'HsDocString'
      TTG instances out of 'GHC.Hs.Extension', which re-exports it unchanged
      (this is backwards compatible and prevents the introduction of a boot file).
    * Deleted 'GHC.Hs.Doc.hs-boot'; removed all 'L.H.S.*' imports of 'GHC.Hs.Doc'.
    * Updated 'GHC.Hs.DocString' to be TTG pass-parameterised throughout; moved
      'mkHsDocStringChunk'/'unpackHDSC' here (require 'GHC.Utils.Encoding').
    * Split 'GHC.Rename.Doc.rnHsDoc' from 'rnHsDocIdentifiersOnly'.
    * Updated parser, renamer, typechecker, HIE, and exact-print for new types.
    * Added 'HsDocString' TTG instances for 'DocNameI' to 'Haddock.Types'.
    * Killed the last module loop between GHC.* and LHS.*.
          - Only edges from LHS.* to GHC.Data.FastString now!
  
  Resolves #26971
  

• b7e24044
  by mangoiv at 2026-07-04T04:14:56-04:00

  ci: retry fetching test metrics
  
  Retry fetching test metrics to make the CI not fail if the services is
  temporarily unavailable
  

• 4180af3f
  by Zubin Duggal at 2026-07-04T04:15:38-04:00

  Bump semaphore-compat submodule to 2.0.1
  
  This versions includes some cruicial fixes for darwin
  

• 242d4317
  by sheaf at 2026-07-04T04:16:19-04:00

  Remove outdated comment in GHC.Data.ShortText
  
  There was a long comment in GHC.Data.ShortText about a workaround that
  was necessary when bootstrapping with GHC 9.2 and below. The actual
  logic has since been dropped, but the comment remained. This commit
  removes the vestigial comment.
  

• 9b714c4c
  by Zubin Duggal at 2026-07-05T09:40:36+05:30

  CorePrep: Don't speculatively evaluate bindings that we have already discovered to be absent
  
  In #25924, we segfault because speculation forces a projection out of a RUBBISH dictionary
  (which we generated because it absent).
  
  Solution: Don't speculate on bindings we already know are absent.
  
  Fixes 25924
  

• 4a59b3ee
  by Zubin Duggal at 2026-07-05T09:40:36+05:30

  Don't make absent fillers for terminating types
  
  In #25924 we discovered that we could speculatively evaluate an absent filler
  for a dictionary, and project a field (a superclass selector) out of it,
  resulting in segfaults.
  
  Solution: Never make an absent filler or rubbish literal for a terminating type
  like a dictionary. mkAbsentFiller returns Nothing for isTerminatingType, so
  worker/wrapper and the specialiser keep the real argument instead.
  
  Some small metric decreases because we do a little less work in the
  simplifier now.
  
  Metric Decrease:
      T9872a
      T9872b
      T9872c
      TcPlugin_RewritePerf
  

• 383ddcd4
  by Alan Zimmerman at 2026-07-06T07:08:16-04:00

  EPA: Move the 'where' annotation for PatSynBind
  
  This allows us to move it out of the MatchGroup exact print annotation
  too
  

• 388446cf
  by Duncan Coutts at 2026-07-06T14:55:28+01:00

  Move THREADED_RTS-conditional struct members to end of Capability
  
  Accessing members of the Capability struct from CMM code rely on
  accessor macros. (The macros are generated by deriveConstants).
  
  These macros have a single definition. This means that the offsets of
  all struct members must *not* vary based on THREADED_RTS vs
  !THREADED_RTS. This requires that any struct members that are
  conditional on THREADED_RTS must occur after the unconditional struct
  members. Hence we move all the ones that are conditional on
  THREADED_RTS to the end.
  
  Add a deriveConstants entry for the iomgr member of the Capability
  struct, which was the motivation for this change.
  
  Add warning messages to help our future selves. Debugging this took me
  a couple hours in gdb!
  

• 3aa51ecf
  by Duncan Coutts at 2026-07-06T14:55:29+01:00

  Make the IOManager API use CapIOManager rather than Capability
  
  This makes the API somewhat more self-contained and more consistent.
  Now the IOManager API and each of the backends takes just the I/O
  manager structure. Previously we had a bit of a mixture, depending on
  whether the function needed access to the Capability or just the
  CapIOManager.
  
  We still need access to the cap, so we introduce a back reference to
  reach the capability, via iomgr->cap.
  
  Convert all uses in select and poll backends, but not win32 ones.
  Convert callers in the scheduler and elsewhere.
  
  Also convert the three CMM primops that call IOManager APIs. They just
  need to use Capability_iomgr(MyCapability()).
  

• 3e5f3cd9
  by Duncan Coutts at 2026-07-06T14:55:29+01:00

  Split posix/MIO.c out of posix/Signals.c
  
  The MIO I/O manager was secretly living inside the Signals file.
  
  Now it gets its own file, like any other self-respecting I/O manager.
  

• 5b26ba34
  by Duncan Coutts at 2026-07-06T14:55:29+01:00

  Rationalise some scheduler run queue utilities
  
  Move them all to the same place in the file.
  
  Make some static that were used only internally.
  
  Also remove a redundant assignment after calling truncateRunQueue that
  is already done within truncateRunQueue.
  

• 98f0c19c
  by Duncan Coutts at 2026-07-06T14:55:29+01:00

  Rename initIOManager{AfterFork} to {re}startIOManager
  
  These are more accurate names, since these actions happen after
  initialisation and are really about starting (or restarting) background
  threads.
  

• 268152b0
  by Duncan Coutts at 2026-07-06T14:55:29+01:00

  Free per-cap I/O managers during shutdown and forkProcess
  
  Historically this was not strictly necessary. The select and win32
  legacy I/O managers did not maintain any dynamically allocated
  resources. The new poll one does (an auxillary table), and so this
  should be freed.
  
  After forkProcess, all threads get deleted. This includes threads
  waiting on I/O or timers. So as of this patch, resetting the I/O
  manager is just about tidying things up. For example, for the poll
  I/O manager this will reset the size of the AIOP table (which
  otherwise grows but never shrinks).
  
  In future however the re-initialising will become neeecessary for
  functionality, since some I/O managers will need to re-initialise
  wakeup fds that are set CLOEXEC.
  

119 changed files:

• .gitlab/test-metrics.sh
• + changelog.d/fix-absent-dict-projection
• changelog.d/semaphore-v2
• compiler/GHC/Builtin/Utils.hs
• compiler/GHC/Core/Make.hs
• compiler/GHC/Core/Opt/Specialise.hs
• compiler/GHC/Core/Opt/WorkWrap.hs
• compiler/GHC/Core/Opt/WorkWrap/Utils.hs
• compiler/GHC/CoreToStg/Prep.hs
• compiler/GHC/Hs.hs
• compiler/GHC/Hs/Binds.hs
• compiler/GHC/Hs/Doc.hs
• − compiler/GHC/Hs/Doc.hs-boot
• compiler/GHC/Hs/DocString.hs
• compiler/GHC/Hs/Dump.hs
• compiler/GHC/Hs/Expr.hs
• compiler/GHC/Hs/Extension.hs
• + compiler/GHC/Hs/Extension/Pass.hs
• compiler/GHC/Hs/ImpExp.hs
• compiler/GHC/Hs/Utils.hs
• compiler/GHC/HsToCore/Docs.hs
• compiler/GHC/Iface/Ext/Ast.hs
• compiler/GHC/Iface/Syntax.hs
• compiler/GHC/Parser.y
• compiler/GHC/Parser/Annotation.hs
• compiler/GHC/Parser/HaddockLex.x
• compiler/GHC/Parser/Lexer.x
• compiler/GHC/Parser/PostProcess.hs
• compiler/GHC/Parser/PostProcess/Haddock.hs
• compiler/GHC/Parser/Types.hs
• compiler/GHC/Rename/Bind.hs
• compiler/GHC/Rename/Doc.hs
• compiler/GHC/Rename/Module.hs
• compiler/GHC/Rename/Utils.hs
• compiler/GHC/Tc/Errors/Hole.hs
• compiler/GHC/Tc/Errors/Hole/FitTypes.hs
• compiler/GHC/Tc/Gen/Arrow.hs
• compiler/GHC/Tc/Gen/Do.hs
• compiler/GHC/Tc/Gen/Expr.hs
• compiler/GHC/Tc/Gen/Match.hs
• compiler/GHC/Tc/Gen/Splice.hs
• compiler/GHC/Tc/Module.hs
• compiler/GHC/Tc/TyCl/PatSyn.hs
• compiler/GHC/ThToHs.hs
• compiler/GHC/Types/Basic.hs
• compiler/GHC/Types/Literal.hs
• compiler/Language/Haskell/Syntax.hs
• compiler/Language/Haskell/Syntax/Decls.hs
• + compiler/Language/Haskell/Syntax/Doc.hs
• compiler/Language/Haskell/Syntax/Expr.hs-boot
• compiler/Language/Haskell/Syntax/Extension.hs
• compiler/Language/Haskell/Syntax/ImpExp.hs
• compiler/Language/Haskell/Syntax/Type.hs
• − compiler/Language/Haskell/Syntax/Type.hs-boot
• compiler/ghc.cabal.in
• hadrian/src/Settings/Warnings.hs
• libraries/ghc-boot/GHC/Data/ShortText.hs
• libraries/semaphore-compat
• rts/Capability.c
• rts/Capability.h
• rts/IOManager.c
• rts/IOManager.h
• rts/IOManagerInternals.h
• rts/PrimOps.cmm
• rts/RaiseAsync.c
• rts/RtsStartup.c
• rts/Schedule.c
• rts/Schedule.h
• + rts/posix/MIO.c
• + rts/posix/MIO.h
• rts/posix/Poll.c
• rts/posix/Poll.h
• rts/posix/Select.c
• rts/posix/Select.h
• rts/posix/Signals.c
• rts/posix/Signals.h
• rts/posix/Timeout.c
• rts/posix/Timeout.h
• rts/rts.cabal
• testsuite/driver/testlib.py
• + testsuite/tests/core-to-stg/T25924/B.hs
• + testsuite/tests/core-to-stg/T25924/Main.hs
• + testsuite/tests/core-to-stg/T25924/all.T
• + testsuite/tests/core-to-stg/T25924a.hs
• + testsuite/tests/core-to-stg/T25924a.stdout
• testsuite/tests/core-to-stg/all.T
• testsuite/tests/count-deps/CountDepsAst.stdout
• testsuite/tests/count-deps/CountDepsParser.stdout
• testsuite/tests/dmdanal/should_compile/T18982.stderr
• testsuite/tests/ghc-api/exactprint/T22919.stderr
• testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr
• testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr
• testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr
• testsuite/tests/module/mod185.stderr
• testsuite/tests/parser/should_compile/DumpParsedAst.stderr
• testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr
• testsuite/tests/parser/should_compile/DumpRenamedAst.stderr
• testsuite/tests/parser/should_compile/DumpSemis.stderr
• testsuite/tests/parser/should_compile/DumpTypecheckedAst.stderr
• testsuite/tests/parser/should_compile/KindSigs.stderr
• testsuite/tests/parser/should_compile/T15279.stderr
• testsuite/tests/parser/should_compile/T20718.stderr
• testsuite/tests/parser/should_compile/T20846.stderr
• testsuite/tests/parser/should_compile/T23315/T23315.stderr
• testsuite/tests/parser/should_compile/all.T
• testsuite/tests/printer/Test20297.stdout
• testsuite/tests/printer/Test24533.stdout
• testsuite/tests/showIface/DocsInHiFile1.stdout
• testsuite/tests/showIface/HaddockSpanIssueT24378.stdout
• testsuite/tests/showIface/MagicHashInHaddocks.stdout
• testsuite/tests/showIface/NoExportList.stdout
• testsuite/tests/simplCore/should_compile/T26615.stderr
• utils/check-exact/ExactPrint.hs
• utils/check-exact/Utils.hs
• utils/deriveConstants/Main.hs
• utils/haddock/haddock-api/src/Haddock/Interface/Create.hs
• utils/haddock/haddock-api/src/Haddock/Interface/LexParseRn.hs
• utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs
• utils/haddock/haddock-api/src/Haddock/Types.hs

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