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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Sebastian Graf pushed to branch wip/T21754
at <a href="https://gitlab.haskell.org/ghc/ghc" style="color: #1068bf;">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
Commits:
</h4>
<ul>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/aeafdba5503b8d26a62dc7bc7078caef170d4154" style="color: #1068bf;">aeafdba5</a></strong>
<div>
<span>by Sebastian Graf</span>
<i>at 2022-09-27T15:14:54+02:00</i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.8125rem; color: #303030; position: relative; font-family: "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: #fafafa; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dbdbdb;'>Demand: Clear distinction between Call SubDmd and eval Dmd (#21717)
In #21717 we saw a reportedly unsound strictness signature due to an unsound
definition of plusSubDmd on Calls. This patch contains a description and the fix
to the unsoundness as outlined in `Note [Call SubDemand vs. evaluation Demand]`.
This fix means we also get rid of the special handling of `-fpedantic-bottoms`
in eta-reduction. Thanks to less strict and actually sound strictness results,
we will no longer eta-reduce the problematic cases in the first place, even
without `-fpedantic-bottoms`.
So fixing the unsoundness also makes our eta-reduction code simpler with less
hacks to explain. But there is another, more unfortunate side-effect:
We *unfix* #21085, but fortunately we have a new fix ready:
See `Note [mkCall and plusSubDmd]`.
There's another change:
I decided to make `Note [SubDemand denotes at least one evaluation]` a lot
simpler by using `plusSubDmd` (instead of `lubPlusSubDmd`) even if both argument
demands are lazy. That leads to less precise results, but in turn rids ourselves
from the need for 4 different `OpMode`s and the complication of
`Note [Manual specialisation of lub*Dmd/plus*Dmd]`. The result is simpler code
that is in line with the paper draft on Demand Analysis.
I left the abandoned idea in `Note [Unrealised opportunity in plusDmd]` for
posterity. The fallout in terms of regressions is negligible, as the testsuite
and NoFib shows.
```
Program Allocs Instrs
--------------------------------------------------------------------------------
hidden +0.2% -0.2%
linear -0.0% -0.7%
--------------------------------------------------------------------------------
Min -0.0% -0.7%
Max +0.2% +0.0%
Geometric Mean +0.0% -0.0%
```
Fixes #21717.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9b1595c87f0c2406bb340c5e27a4a45dfcde0e2c" style="color: #1068bf;">9b1595c8</a></strong>
<div>
<span>by Ross Paterson</span>
<i>at 2022-09-27T14:12:01-04:00</i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.8125rem; color: #303030; position: relative; font-family: "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: #fafafa; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dbdbdb;'>implement proposal 106 (Define Kinds Without Promotion) (fixes #6024)
includes corresponding changes to haddock submodule
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3bf718f71ec57e09e20a93344c8e04ebdc49eb34" style="color: #1068bf;">3bf718f7</a></strong>
<div>
<span>by Sebastian Graf</span>
<i>at 2022-09-28T10:38:45+02:00</i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.8125rem; color: #303030; position: relative; font-family: "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: #fafafa; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dbdbdb;'>Boxity: Don't update Boxity unless worker/wrapper follows (#21754)
A small refactoring in our Core Opt pipeline and some new functions for
transfering argument boxities from one signature to another to facilitate
`Note [Don't change boxity without worker/wrapper]`.
Fixes #21754.
</pre>
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<a href="#6fcf64907fb5bdd93082d2d1eb94e4566e735865" style="color: #1068bf;">
compiler/GHC/Core/DataCon.hs
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compiler/GHC/Core/Opt/Arity.hs
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<a href="#8104fa1b71db6cfc4eb90cd769463d9eb9004619" style="color: #1068bf;">
compiler/GHC/Core/Opt/DmdAnal.hs
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compiler/GHC/Core/Opt/Pipeline.hs
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compiler/GHC/Core/Opt/Pipeline/Types.hs
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compiler/GHC/Core/Opt/Simplify/Utils.hs
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compiler/GHC/Driver/Config/Core/Lint.hs
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