[Git][ghc/ghc][wip/T25445b] 6 commits: Tidy up the handling of `assert`

Simon Peyton Jones (@simonpj) gitlab at gitlab.haskell.org
Mon Dec 16 17:14:01 UTC 2024



Simon Peyton Jones pushed to branch wip/T25445b at Glasgow Haskell Compiler / GHC


Commits:
64756530 by Simon Peyton Jones at 2024-12-14T22:28:04-05:00
Tidy up the handling of `assert`

Fixes #25493

- - - - -
8658fbc1 by Rodrigo Mesquita at 2024-12-14T22:28:41-05:00
base: displayException for SomeAsyncException

Provide a better implementation of `SomeException` for
`SomeAsyncException`.
The previous, implicit, implementation, would not use the
`displayException` of the exception wrapped by `SomeAsyncException`.

Implements CLC-Proposal#309

Closes #25513

- - - - -
2d3a0a70 by ARATA Mizuki at 2024-12-15T18:35:30-05:00
LLVM: When emitting a vector literal with ppTypeLit, include the type information

Fixes #25561

- - - - -
bfacc086 by Simon Peyton Jones at 2024-12-15T18:36:05-05:00
Fix signature lookup in instance declarations

This fixes a bug introduced by the fix to #16610

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80f0e02d by Simon Peyton Jones at 2024-12-16T17:13:52+00:00
Improve GHC build times

Two small changes

* In GHC.Data.Unboxed, never omit interface pragmas.  In "fast builds"
  one might omit them generally, but doing so gives very bad
  performance for code that imports this module.

* In GHC.Hs.Dump don't do type-class specialisation.  For some reason
  it goes mad and generates vast amounts of useless code.  See #25463.

- - - - -
175a1355 by Simon Peyton Jones at 2024-12-16T17:13:52+00:00
Refactor Lint

Refactor Lint for two reasons:

* To improve performance
* To prepare for type-lets

The big changes are all in GHC.Core.Lint:

* Change the main APIs:
  * `lintType` returns nothing rather than returning a `LintedType`;
  * `lintCoercion` return nothing rather than returning a `LintedCoercion`
  Reason: these functions did a lot of allocation to return a substituted
  type/coercion that was often discarded, or used only to extract its kind.

  Instead we now return nothing, and, when needed, extract the kind and
  substitute.

* Applications are treated as a whole, by `lintApp`.  By treating
  multiple arguments all at once we avoid performing multiple
  substitutions, each substituting a single type variable. This can
  make an absolutely huge difference.

Overall this led to a pretty massive rewrite of Lint, with many smaller
changes.

Smaller chnages elsewhere

* Rename `GHC.Core.TyCo.Subst.getSubstInScope` to `substInScopeSet` for consistency

* Define and use `GHC.Core.Type.liftedTypeOrConstraintKind`

Performance. This MR someimtes gives gives a very large improvement in
compile time, when Lint is on.  here is a selection of changes over 5%
in perf/compiler (with -dcore-lint)

      T25196                       -97.0%
      T14766                       -89.7%
      T14683                       -74.4%
      T5631                        -60.9%
      T20261                       -56.7%
      T18923                       -17.6%
      T13035                       -15.8%
      T6048                        -15.8%
      CoOpt_Read                   -14.4%
      T9630                        -10.9%
      T5642                         -7.3%

Eliminating the egregious offenders is a big win.

However, in some cases the compiler allocation /increases/. Here ae the
changes over 1%:

      T9961                          1.5%
      T8095                          2.8%
      T14052                         3.9%
      T12545                         4.5%
      T14052Type                     5.5%
      T5030                          8.0%
      T5321Fun                       8.3%
      T3064                         12.7%
      CoOpt_Singletons              15.6%
      T9198                         16.0%
      LargeRecord                   18.1%

I looked at the two biggest increases in compile-time bytes allocated.  Interestingly,
they both show substantial *decreases* in actual compile time, due to much smaller GC times.
I'm honestly not sure either why the allocation increases, or why the GC time decreases;
but I'm going to take the win!

    T9198
                 Baseline            With patch
    No Lint
      Alloc       44.6M              44.6M
      Mut time    0.23s              0.22s
      GC time     0.21s              0.21s

    With Lint
      Alloc       309M               360M
      Mut time    1.51s              0.85s
      GC time     2.97s              0.25s

    -------------------
    LargeRecord
                 Baseline            With patch
    No Lint
      Alloc       1.37G              1.37G
      Mut time    2.33s              2.33s
      GC time     2.40s              2.42s

    With Lint
      Alloc       3.4G               4.0G
      Mut time    6.02s              5.68s
      GC time     3.67s              3.03s

IMPORTANT NOTE: These changes don't show up in CI because in CI the
tests in perf/compiler are all run with -dcore-lint switched off.  I
gathered this data with some manual runs.

- - - - -


30 changed files:

- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/SpecConstr.hs
- compiler/GHC/Core/Opt/Specialise.hs
- compiler/GHC/Core/SimpleOpt.hs
- compiler/GHC/Core/Subst.hs
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCo/Subst.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Data/Unboxed.hs
- compiler/GHC/Hs/Dump.hs
- compiler/GHC/Llvm/Ppr.hs
- compiler/GHC/Rename/Bind.hs
- compiler/GHC/Rename/Env.hs
- compiler/GHC/Tc/Gen/Head.hs
- compiler/GHC/Tc/Solver/Equality.hs
- compiler/GHC/Tc/TyCl.hs
- compiler/GHC/Tc/Utils/TcType.hs
- compiler/GHC/Types/Var.hs
- libraries/base/changelog.md
- libraries/ghc-internal/src/GHC/Internal/Base.hs
- libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs
- + testsuite/tests/rename/should_fail/T25437.hs
- + testsuite/tests/rename/should_fail/T25437.stderr
- testsuite/tests/rename/should_fail/T5001b.stderr
- testsuite/tests/rename/should_fail/all.T
- + testsuite/tests/simd/should_run/T25561.hs
- + testsuite/tests/simd/should_run/T25561.stdout


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b507e652e201674d60d08c075319e72159461643...175a1355341e5594ae16515b485c3ebedb88c057

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b507e652e201674d60d08c075319e72159461643...175a1355341e5594ae16515b485c3ebedb88c057
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