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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Simon Peyton Jones pushed to branch wip/T25445b at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
Commits:
</h4>
<ul>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/64756530071afccf6ab339e8ee7bf4cad598b931">64756530</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2024-12-14T22:28:04-05:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Tidy up the handling of `assert`
Fixes #25493
</pre>
</li>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8658fbc15fa2d73636eeca0b75848e61091d7960">8658fbc1</a></strong>
<div>
<span> by Rodrigo Mesquita </span> <i> at 2024-12-14T22:28:41-05:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>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
</pre>
</li>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2d3a0a70def8a2044f2954b29df1a186b3f08dcc">2d3a0a70</a></strong>
<div>
<span> by ARATA Mizuki </span> <i> at 2024-12-15T18:35:30-05:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>LLVM: When emitting a vector literal with ppTypeLit, include the type information
Fixes #25561
</pre>
</li>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/bfacc086604c18e30758772a05a8c81e3a4e01bc">bfacc086</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2024-12-15T18:36:05-05:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Fix signature lookup in instance declarations
This fixes a bug introduced by the fix to #16610
</pre>
</li>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/80f0e02dae5ea257fb5b1107ba551583d369e7c1">80f0e02d</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2024-12-16T17:13:52+00:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>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.
</pre>
</li>
<li>
<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/175a1355341e5594ae16515b485c3ebedb88c057">175a1355</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2024-12-16T17:13:52+00:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #28272d; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>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.
</pre>
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<a href="#182d6a315e784018aa9c8b2ad736036b97bd5d48">
compiler/GHC/Core.hs
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<a href="#783e5dae6e86931f06700fc088fb7d48c8a07386">
compiler/GHC/Core/Coercion.hs
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<a href="#36a42448a83a9d1f6df8475f03ead2eed199dd8e">
compiler/GHC/Core/Lint.hs
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<a href="#c3967bb9d3e8f5aae2dd111b5a335b48c21c1999">
compiler/GHC/Core/Opt/Arity.hs
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compiler/GHC/Core/Opt/SpecConstr.hs
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compiler/GHC/Core/Opt/Specialise.hs
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compiler/GHC/Core/SimpleOpt.hs
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compiler/GHC/Core/Subst.hs
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<a href="#578c7c3857d66d963736ff6742f3433a0e8d01b7">
compiler/GHC/Core/TyCo/Rep.hs
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compiler/GHC/Core/TyCo/Subst.hs
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compiler/GHC/Core/Type.hs
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compiler/GHC/Data/Unboxed.hs
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compiler/GHC/Hs/Dump.hs
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compiler/GHC/Llvm/Ppr.hs
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compiler/GHC/Rename/Bind.hs
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compiler/GHC/Rename/Env.hs
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compiler/GHC/Tc/Gen/Head.hs
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compiler/GHC/Tc/Solver/Equality.hs
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compiler/GHC/Tc/TyCl.hs
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compiler/GHC/Tc/Utils/TcType.hs
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compiler/GHC/Types/Var.hs
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libraries/base/changelog.md
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libraries/ghc-internal/src/GHC/Internal/Base.hs
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libraries/ghc-internal/src/GHC/Internal/IO/Exception.hs
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testsuite/tests/rename/should_fail/T25437.hs
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testsuite/tests/rename/should_fail/T5001b.stderr
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testsuite/tests/rename/should_fail/all.T
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