Sven Tennie pushed to branch wip/romes/hadrian-cross-stage2-rebase_SVEN_FINAL at Glasgow Haskell Compiler / GHC

Commits:

• 29c0aceb
  by Simon Peyton Jones at 2026-01-16T17:18:11-05:00

  Improve newtype unwrapping
  
  Ticket #26746 describes several relatively-minor shortcomings of newtype
  unwrapping.  This MR addresses them, while also (arguably) simplifying
  the code a bit.
  
  See new Note [Solving newtype equalities: overview]
  and     Note [Decomposing newtype equalities]
  and     Note [Eager newtype decomposition]
  and     Note [Even more eager newtype decomposition]
  
  For some reason, on Windows only, runtime allocations decrease for test
  T5205 (from 52k to 48k).  I have not idea why. No change at all on Linux.
  I'm just going to accept the change.  (I saw this same effect in another
  MR so I think it's a fault in the baseline.)
  
  Metric Decrease:
      T5205
  

• 8b59e62c
  by Andreas Klebinger at 2026-01-16T17:18:52-05:00

  testsuite: Widen acceptance window for T5205.
  
  Fixes #26782
  

• 9e5e0234
  by mangoiv at 2026-01-17T06:03:03-05:00

  add a new issue template for getting verified
  
  To reduce spam created by new users, we will in future not grant
  any rights but reporting issues to new users. That is why we will
  have to be able to verify them. The added issue template serves that
  purpose.
  

• b18b2c42
  by Cheng Shao at 2026-01-17T06:03:44-05:00

  llvm: fix split sections for llvm backend
  
  This patch fixes split sections for llvm backend:
  
  - Pass missing `--data-sections`/`--function-sections` flags to
    llc/opt.
  - Use `@llvm.compiler.used` instead of `@llvm.used` to avoid sections
    being unnecessarily retained at link-time.
  
  Fixes #26770.
  
  -------------------------
  Metric Decrease:
      libdir
      size_hello_artifact
      size_hello_unicode
  -------------------------
  
  Co-authored-by: Codex <codex@openai.com>
  

• ebf66f67
  by Cheng Shao at 2026-01-17T13:16:50-05:00

  Update autoconf scripts
  
  Scripts taken from autoconf a2287c3041a3f2a204eb942e09c015eab00dc7dd
  

• 598624b9
  by Andreas Klebinger at 2026-01-17T13:17:32-05:00

  CString.hs: Update incorrect comment.
  
  Fixes #26322
  

• eea2036b
  by Cheng Shao at 2026-01-18T10:00:49-05:00

  libraries: bump haskeline submodule to 0.8.4.1
  
  This patch bumps the haskeline submodule to 0.8.4.1 which includes an
  important fix for an ANSI handling bug on Windows
  (https://github.com/haskell/haskeline/pull/126).
  

• 87d8f6c2
  by Cheng Shao at 2026-01-18T10:01:30-05:00

  hadrian: replace default -H32m/-H64m with -O64M to improve mutator productivity
  
  Most hadrian build flavours pass `-H32m`/`-H64m` to GHC as
  conventional wisdom to improve mutator productivity and reduce GC
  overhead. They were inherited from the legacy Make build system, and
  there used to be make flags to instrument a build process with
  `-Rghc-timing` option to collect GC stats of each GHC run from stderr.
  
  It's time to revisit whether there are better defaults for
  `-H32m`/`-H64m`, and this patch changes it to `-O64M` which indeed
  improves mutator productivity based on real statistics. `-O64M` is
  more aggressive than `-H64m`; it allows the old generation to grow to
  at least 64M before triggering major GC and reduces major GC runs.
  
  The stats of a clean build with `validate` flavour and `-H64m`:
  
  ```
  h64m.log
    matched RTS stat lines: 5499
    sum MUT cpu     : 2400.808 s
    sum GC cpu      : 1378.292 s
    sum MUT elapsed : 2788.253 s
    sum GC elapsed  : 1389.233 s
    GC/MUT cpu ratio     : 0.574 (GC is 57.4% of MUT)
    GC/MUT elapsed ratio : 0.498 (GC is 49.8% of MUT)
    GC fraction of (MUT+GC) cpu     : 36.5%
    GC fraction of (MUT+GC) elapsed : 33.3%
    per-line GC/MUT cpu ratio: median 0.691, p90 1.777
    per-line GC/MUT elapsed ratio: median 0.519, p90 1.081
  ```
  
  The stats of a clean build with `validate` flavour and `-O64M`:
  
  ```
  o64m.log
    matched RTS stat lines: 5499
    sum MUT cpu     : 2377.383 s
    sum GC cpu      : 1127.146 s
    sum MUT elapsed : 2758.857 s
    sum GC elapsed  : 1135.587 s
    GC/MUT cpu ratio     : 0.474 (GC is 47.4% of MUT)
    GC/MUT elapsed ratio : 0.412 (GC is 41.2% of MUT)
    GC fraction of (MUT+GC) cpu     : 32.2%
    GC fraction of (MUT+GC) elapsed : 29.2%
    per-line GC/MUT cpu ratio: median 0.489, p90 1.099
    per-line GC/MUT elapsed ratio: median 0.367, p90 0.806
  ```
  
  Mutator time is roughly in the same ballpark, but GC CPU time has
  reduced by 18.22%, and mutator productivity has increased from 63.5%
  to 67.8%.
  

• 8372e13d
  by Cheng Shao at 2026-01-18T10:02:12-05:00

  rts: remove unused .def files from rts/win32
  
  This patch removes unused .def files from `rts/win32`, given we don't
  build .dll files for rts/ghc-internal/ghc-prim at all. Even when we
  resurrect win32 dll support at some point in the future, these .def
  files still contain incorrect symbols anyway and won't be of any use.
  

• f6af485d
  by Cheng Shao at 2026-01-18T10:03:19-05:00

  .gitmodules: use gitlab mirror for the libffi-clib submodule
  
  This patch fixes .gitmodules to use the gitlab mirror for the
  libffi-clib submodule, to make it coherent with other submodules that
  allow ghc developers to experiment with wip branches in submodules for
  ghc patches. Fixes #26783.
  

• 41432d25
  by Cheng Shao at 2026-01-18T10:05:13-05:00

  hadrian: remove the horrible i386 speedHack
  
  When hadrian builds certain rts objects for i386, there's a horrible
  speedHack that forces -fno-PIC even for dynamic ways of those objects.
  This is not compatible with newer versions of gcc/binutils as well as
  clang/lld, and this patch removes it. Fixes #26792.
  

• 2ff7ba49
  by Matthew Pickering at 2026-01-18T19:06:53+01:00

  Add missing req_interp modifier to T18441fail3 and T18441fail19
  
  These tests require the interpreter but they were failing in a different
  way with the javascript backend because the interpreter was disabled and
  stderr is ignored by the test.
  

• ecc69c0c
  by Matthew Pickering at 2026-01-18T19:06:53+01:00

  Use explicit syntax rather than pure
  

• 990d07f0
  by Matthew Pickering at 2026-01-18T19:06:53+01:00

  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
  

• 1fe43aae
  by Matthew Pickering at 2026-01-18T19:06:53+01:00

  hadrian: Fill in more of the default.host toolchain file
  
  When you are building a cross compiler this file will be used to build
  stage1 and it's libraries, so we need enough information here to work
  accurately. There is still more work to be done (see for example, word
  size is still fixed).
  

• 3a92728f
  by Matthew Pickering at 2026-01-18T19:06:53+01:00

  hadrian: Disable docs when cross compiling
  
  Before there were a variety of ad-hoc places where doc building was
  disabled when cross compiling.
  
  * Some CI jobs sets --docs=none in gen_ci.hs
  * Some CI jobs set --docs=none in .gitlab/ci.sh
  * There was some logic in hadrian to not need the ["docs"] target when
    making a bindist.
  
  Now the situation is simple:
  
  * If you are cross compiling then defaultDocsTargets is empty by
    default.
  
  In theory, there is no reason why we can't build documentation for cross
  compiler bindists, but this is left to future work to generalise the
  documentation building rules to allow this (#24289)
  

• 21b4d783
  by Matthew Pickering at 2026-01-18T19:16:19+01:00

  hadrian: Build stage 2 cross compilers
  
  * Most of hadrian is abstracted over the stage in order to remove the
    assumption that the target of all stages is the same platform. This
    allows the RTS to be built for two different targets for example.
  * Abstracts the bindist creation logic to allow building either normal
    or cross bindists. Normal bindists use stage 1 libraries and a stage 2
    compiler. Cross bindists use stage 2 libararies and a stage 2
    compiler.
  * hadrian: Make binary-dist-dir the default build target. This allows us
    to have the logic in one place about which libraries/stages to build
    with cross compilers. Fixes #24192
  
  New hadrian target:
  
  * `binary-dist-dir-cross`: Build a cross compiler bindist (compiler =
    stage 1, libraries = stage 2)
  
  This commit also contains various changes to make stage2 compilers
  feasible.
  
  -------------------------
  Metric Decrease:
      ManyAlternatives
      MultiComponentModulesRecomp
      MultiLayerModulesRecomp
      T10421
      T12425
      T12707
      T13035
      T13379
      T15703
      T16577
      T18698a
      T18698b
      T18923
      T1969
      T21839c
      T3294
      T4801
      T5030
      T5321Fun
      T5642
      T783
      T9198
      T9872d
      T9961
      parsing001
      T5321FD
      T6048
  -------------------------
  
  Co-authored-by: Sven Tennie <sven.tennie@gmail.com>
  

• bc5de15c
  by Sven Tennie at 2026-01-18T19:16:19+01:00

  Align CI scripts with master
  
  Fixup
  

• d1491a63
  by Matthew Pickering at 2026-01-18T19:16:19+01:00

  ci: Test cross bindists
  
  We remove the special logic for testing in-tree cross
  compilers and instead test cross compiler bindists, like we do for all
  other platforms.
  

• a2cbcd99
  by Matthew Pickering at 2026-01-18T19:16:19+01:00

  ci: Introduce CROSS_STAGE variable
  
  In preparation for building and testing stage3 bindists we introduce the
  CROSS_STAGE variable which is used by a CI job to determine what kind of
  bindist the CI job should produce.
  
  At the moment we are only using CROSS_STAGE=2 but in the future we will
  have some jobs which set CROSS_STAGE=3 to produce native bindists for a
  target, but produced by a cross compiler, which can be tested on by
  another CI job on the native platform.
  
  CROSS_STAGE=2: Build a normal cross compiler bindist
  CROSS_STAGE=3: Build a stage 3 bindist, one which is a native compiler and library for the target
  

• 001b1d84
  by Matthew Pickering at 2026-01-18T19:16:19+01:00

  hadrian: Refactor system-cxx-std-lib rules0
  
  I noticed a few things wrong with the hadrian rules for `system-cxx-std-lib` rules.
  
  * For `text` there is an ad-hoc check to depend on `system-cxx-std-lib` outside of `configurePackage`.
  * The `system-cxx-std-lib` dependency is not read from cabal files.
  * Recache is not called on the packge database after the `.conf` file is generated, a more natural place for this rule is `registerRules`.
  
  Treating this uniformly like other packages is complicated by it not having any source code or a cabal file. However we can do a bit better by reporting the dependency firstly in `PackageData` and then needing the `.conf` file in the same place as every other package in `configurePackage`.
  
  Fixes #25303
  

• 0c82f141
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  ci: Increase timeout for emulators
  
  Test runs with emulators naturally take longer than on native machines.
  
  Generate jobs.yml
  

• cef6cbd9
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  ghc: Distinguish between having an interpreter and having an internal one
  
  Otherwise, we fail with warnings when compiling tools. Actually, these
  are related but different things:
  
  - ghc can run an interpreter (either internal or external)
  - ghc is compiled with an internal interpreter
  

• 31b3d03f
  by Matthew Pickering at 2026-01-18T19:16:20+01:00

  ci: Javascript don't set CROSS_EMULATOR
  
  There is no CROSS_EMULATOR needed to run javascript binaries, so we
  don't set the CROSS_EMULATOR to some dummy value.
  

• 67984106
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  Javascript skip T23697
  
  See #22355 about how HSC2HS and the Javascript target don't play well
  together.
  

• 6b4bf022
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  Mark T24602 as fragile
  
  It was skipped before (due to CROSS_EMULATOR being set, which changed
  for JS), so we don't make things worse by marking it as fragile.
  

• 2a8e33f0
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  Windows needs NM_STAGE0 as well
  
  The stage0 always needs nm.
  

• f0902dfe
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  T17912 sometimes works for windows-validate
  
  This seems to be timing related. However, just simply increasing the
  timeout (sleep) statement of this test didn't help. Maybe, it has been
  flaky on CI before.
  

• f8f82145
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  Fix rebase: settings-use-distro-mingw is now staged
  

• 11f70549
  by Sven Tennie at 2026-01-18T19:16:20+01:00

  TextFile should contain no logic
  
  It's very confusing to query for one file and then get another...
  

103 changed files:

• .gitlab/ci.sh
• .gitlab/generate-ci/gen_ci.hs
• + .gitlab/issue_templates/get-verified.md
• .gitlab/jobs.yaml
• .gitmodules
• compiler/GHC/CmmToLlvm.hs
• compiler/GHC/CmmToLlvm/Base.hs
• compiler/GHC/Core/FamInstEnv.hs
• compiler/GHC/Driver/Pipeline/Execute.hs
• compiler/GHC/Tc/Instance/Family.hs
• compiler/GHC/Tc/Solver/Equality.hs
• compiler/GHC/Tc/Solver/Monad.hs
• config.guess
• config.sub
• configure.ac
• distrib/configure.ac.in
• ghc/GHC/Driver/Session/Mode.hs
• ghc/GHCi/UI.hs
• ghc/Main.hs
• ghc/ghc-bin.cabal.in
• hadrian/README.md
• hadrian/bindist/config.mk.in
• hadrian/cfg/default.host.target.in
• + hadrian/cfg/system.config.host.in
• hadrian/cfg/system.config.in
• + hadrian/cfg/system.config.target.in
• hadrian/doc/flavours.md
• hadrian/hadrian.cabal
• hadrian/src/Base.hs
• + hadrian/src/BindistConfig.hs
• hadrian/src/Builder.hs
• hadrian/src/Context.hs
• hadrian/src/Expression.hs
• hadrian/src/Flavour.hs
• hadrian/src/Flavour/Type.hs
• hadrian/src/Hadrian/Builder.hs
• hadrian/src/Hadrian/Haskell/Cabal/Parse.hs
• hadrian/src/Hadrian/Haskell/Cabal/Type.hs
• hadrian/src/Hadrian/Haskell/Hash.hs
• hadrian/src/Hadrian/Oracles/TextFile.hs
• hadrian/src/Oracles/Flag.hs
• hadrian/src/Oracles/Flavour.hs
• hadrian/src/Oracles/Setting.hs
• hadrian/src/Oracles/TestSettings.hs
• hadrian/src/Packages.hs
• hadrian/src/Rules.hs
• hadrian/src/Rules/BinaryDist.hs
• hadrian/src/Rules/CabalReinstall.hs
• hadrian/src/Rules/Compile.hs
• hadrian/src/Rules/Documentation.hs
• hadrian/src/Rules/Generate.hs
• hadrian/src/Rules/Gmp.hs
• + hadrian/src/Rules/Libffi.hs
• hadrian/src/Rules/Library.hs
• hadrian/src/Rules/Program.hs
• hadrian/src/Rules/Register.hs
• hadrian/src/Rules/Test.hs
• hadrian/src/Settings.hs
• hadrian/src/Settings/Builders/Cabal.hs
• hadrian/src/Settings/Builders/Common.hs
• hadrian/src/Settings/Builders/Configure.hs
• hadrian/src/Settings/Builders/DeriveConstants.hs
• hadrian/src/Settings/Builders/Ghc.hs
• hadrian/src/Settings/Builders/Hsc2Hs.hs
• hadrian/src/Settings/Builders/RunTest.hs
• hadrian/src/Settings/Builders/SplitSections.hs
• hadrian/src/Settings/Default.hs
• hadrian/src/Settings/Flavours/Benchmark.hs
• hadrian/src/Settings/Flavours/Development.hs
• hadrian/src/Settings/Flavours/GhcInGhci.hs
• hadrian/src/Settings/Flavours/Performance.hs
• hadrian/src/Settings/Flavours/Quick.hs
• hadrian/src/Settings/Flavours/QuickCross.hs
• hadrian/src/Settings/Flavours/Quickest.hs
• hadrian/src/Settings/Flavours/Validate.hs
• hadrian/src/Settings/Packages.hs
• hadrian/src/Settings/Program.hs
• hadrian/src/Settings/Warnings.hs
• libraries/base/tests/IO/all.T
• libraries/base/tests/all.T
• libraries/ghc-internal/src/GHC/Internal/CString.hs
• libraries/haskeline
• m4/fp_find_nm.m4
• m4/fptools_set_platform_vars.m4
• m4/prep_target_file.m4
• − rts/win32/libHSffi.def
• − rts/win32/libHSghc-internal.def
• − rts/win32/libHSghc-prim.def
• testsuite/ghc-config/ghc-config.hs
• testsuite/tests/deriving/should_fail/T8984.stderr
• testsuite/tests/deriving/should_fail/deriving-via-fail.stderr
• testsuite/tests/deriving/should_fail/deriving-via-fail4.stderr
• testsuite/tests/deriving/should_fail/deriving-via-fail5.stderr
• testsuite/tests/ghc-e/should_fail/all.T
• testsuite/tests/javascript/closure/all.T
• testsuite/tests/perf/should_run/all.T
• + testsuite/tests/typecheck/should_compile/T26746.hs
• testsuite/tests/typecheck/should_compile/all.T
• testsuite/tests/typecheck/should_fail/T15801.stderr
• testsuite/tests/typecheck/should_fail/T22924b.stderr
• testsuite/tests/typecheck/should_fail/TcCoercibleFail.hs
• testsuite/tests/typecheck/should_fail/TcCoercibleFail.stderr
• testsuite/tests/typecheck/should_fail/all.T

The diff was not included because it is too large.