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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Sebastian Graf pushed to branch wip/T23083 at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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<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/a2050f56fd78ca6bf1610cae830fa650189e61fd">a2050f56</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-04-27T16:13:05+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Inlining literals into boring contexts is OK
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/09940bdeaada8565ea16a0827dd52f2337f508dc">09940bde</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-04-27T16:13:12+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Kill SetLevel.notWorthFloating.is_triv (#23270)
We have had it since b84ba676034, when it operated on annotated expressions.
Nowadays it operates on vanilla `CoreExpr` though, so we should just call
`exprIsTrivial`; thus handling empty cases and string literals correctly.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/85d1fb5986c507e5ce116fcec9bebda8ee8e25d0">85d1fb59</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-04-27T16:34:32+02:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>ANFise string literal arguments (#23270)
This instates the invariant that a trivial CoreExpr translates to an atomic
StgExpr. Nice.
Fixes #23270.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b39167566ed0301426fc335b63266b24572c2295">b3916756</a></strong>
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<span> by Sebastian Graf </span> <i> at 2023-04-27T16:35:50+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>CorePrep: Do not eliminate EmptyCase, do it in StgToCmm instead
We eliminate EmptyCase by way of `cgCase e _ _ [] = cgExpr e` now.
The main reason is that it plays far better in conjunction with eta expansion
(as we aim to do for arguments in CorePrep, #23083), because we can discard
any arguments, `(case e of {}) eta == case e of {}`, whereas in `(e |> co) eta`
it's impossible to discard the argument.
It is also both much simpler to describe than the previous mechanism of emitting
an unsafe coercion and simpler to implement, removing quite a bit of commentary
and the `Bool` field of `CorePrepProv`.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e6893f0a1eb36d59cbd7a1c13434b8216083f35b">e6893f0a</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-04-27T16:35:50+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>CorePrep: Eta expand arguments (#23083)
Previously, we'd only eta expand let bindings and lambdas,
now we'll also eta expand arguments such as in T23083:
```hs
g f h = f (h `seq` (h $))
```
Unless `-fpedantic-bottoms` is set, we'll now transform to
```hs
g f h = f (\eta -> h eta)
```
in CorePrep.
See the new `Note [Eta expansion of arguments in CorePrep]` for the details.
We only do this optimisation with -O2 because we saw 2-3% ghc/alloc regressions
in T4801 and T5321FD.
Fixes #23083.
</pre>
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