<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en" style="--code-editor-font: GitLab Mono, JetBrains Mono, Menlo, DejaVu Sans Mono, Liberation Mono, Consolas, Ubuntu Mono, Courier New, andale mono, lucida console, monospace;">
<head>
<meta content="text/html; charset=US-ASCII" http-equiv="Content-Type">
<title>
GitLab
</title>
<style data-premailer="ignore" type="text/css">
a { color: #1068bf; }
</style>
<style>img {
max-width: 100%; height: auto;
}
body {
font-size: 0.875rem;
}
body {
-webkit-text-shadow: rgba(255,255,255,0.01) 0 0 1px;
}
body {
font-family: "GitLab Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans", Ubuntu, Cantarell, "Helvetica Neue", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji"; font-size: inherit;
}
</style>
</head>
<body style='font-size: inherit; -webkit-text-shadow: rgba(255,255,255,0.01) 0 0 1px; font-family: "GitLab Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans", Ubuntu, Cantarell, "Helvetica Neue", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";'>
<div class="content">
<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>
</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/4395ece2642e5be3290c5db4d242d1ed2ad75acd">4395ece2</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:16+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>Disable tests RepPolyWrappedVar2 and RepPolyUnsafeCoerce1 in JS backend
... because those coerce between incompatible/unknown PrimReps.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6165155a83e48ad4219dd008cbae6f0f9b1eaaeb">6165155a</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>Inlining literals into boring contexts is OK
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b4c3378f8e15931f5504c792cba141b25c07a751">b4c3378f</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>Clarify floating of unsafeEqualityProofs (#23754)
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/13c9d4a12ebec72b2bf49d4d303f3e76d5f8d1ca">13c9d4a1</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>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/e799b6b1f8df68199b28fd0261851cca1c0f8cc0">e799b6b1</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>ANFise string literal arguments (#23270)
This instates the invariant that a trivial CoreExpr translates to an atomic
StgExpr. Nice.
Annoyingly, in -O0 we sometimes generate
```
foo = case "blah"# of sat { __DEFAULT -> unpackCString# sat }
```
which makes it a bit harder to spot that we can emit a standard
`stg_unpack_cstring` thunk.
Fixes #23270.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/298ec2da3a93e782566b29f3656d618e39a68237">298ec2da</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>Deactivate -fcatch-nonexhaustive-cases in ghc-bignum (#23345)
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d5722ebb453e9e613646b55ea8b230ef997205cc">d5722ebb</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>CorePrep: Eliminate EmptyCase and unsafeEqualityProof in CoreToStg instead
We eliminate EmptyCase by way of `coreToStg (Case e _ _ []) = coreToStg 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.
We do also give the same treatment to unsafeCoerce proofs and treat them as
trivial iff their RHS is trivial.
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 `CorePrepProv`.
In the ghc/alloc perf test `LargeRecord`, we introduce an additional Simplifier
iteration due to #17910. E.g., FloatOut produces a binding
```
lvl_s6uK [Occ=Once1] :: GHC.Types.Int
[LclId]
lvl_s6uK = GHC.Types.I# 2#
lvl_s6uL [Occ=Once1] :: GHC.Types.Any
[LclId]
lvl_s6uL
= case Unsafe.Coerce.unsafeEqualityProof ... of
{ Unsafe.Coerce.UnsafeRefl v2_i6tr -> lvl_s6uK `cast` (... v2_i6tr ...)
}
```
That occurs once and hence is pre-inlined unconditionally in the next Simplifier
pass. It's non-trivial to find a way around that, but not really harmful
otherwise. Hence we accept a 1.2% increase on some architectures.
Metric Increase:
LargeRecord
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6d0d74cd0ea03fcf8a75f3e3aa2dd0e226209afc">6d0d74cd</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2023-08-09T09:37:55+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; 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;'>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>
</li>
</ul>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
30 changed files:
</h4>
<ul>
<li class="file-stats">
<a href="#182d6a315e784018aa9c8b2ad736036b97bd5d48">
compiler/GHC/Core.hs
</a>
</li>
<li class="file-stats">
<a href="#783e5dae6e86931f06700fc088fb7d48c8a07386">
compiler/GHC/Core/Coercion.hs
</a>
</li>
<li class="file-stats">
<a href="#975dc08a8e7942b32d621f617d5a9c1b668601dd">
compiler/GHC/Core/Coercion/Opt.hs
</a>
</li>
<li class="file-stats">
<a href="#448d7f6e0151c2014de38dead3a902f511c45b75">
compiler/GHC/Core/FVs.hs
</a>
</li>
<li class="file-stats">
<a href="#36a42448a83a9d1f6df8475f03ead2eed199dd8e">
compiler/GHC/Core/Lint.hs
</a>
</li>
<li class="file-stats">
<a href="#c3967bb9d3e8f5aae2dd111b5a335b48c21c1999">
compiler/GHC/Core/Opt/Arity.hs
</a>
</li>
<li class="file-stats">
<a href="#cc763cdd1967f5d921161a32f64136cfcf0332c5">
compiler/GHC/Core/Opt/SetLevels.hs
</a>
</li>
<li class="file-stats">
<a href="#48fbb5cdea308650de5756521feb28ec68819b9b">
compiler/GHC/Core/Opt/Simplify/Utils.hs
</a>
</li>
<li class="file-stats">
<a href="#039e8f5676356ef05c90af828aae48aac7296e47">
compiler/GHC/Core/TyCo/FVs.hs
</a>
</li>
<li class="file-stats">
<a href="#578c7c3857d66d963736ff6742f3433a0e8d01b7">
compiler/GHC/Core/TyCo/Rep.hs
</a>
</li>
<li class="file-stats">
<a href="#8ee6f6851986ea96987a52f1dbf39228c85c6032">
compiler/GHC/Core/TyCo/Subst.hs
</a>
</li>
<li class="file-stats">
<a href="#0b087d030078c501a74df752a832dd50836eb075">
compiler/GHC/Core/TyCo/Tidy.hs
</a>
</li>
<li class="file-stats">
<a href="#84c9d3ba34173297e7d7747e02caa2e004b164fc">
compiler/GHC/Core/Type.hs
</a>
</li>
<li class="file-stats">
<a href="#2811a7297b8aa206197ac1f5dabd0818e3c7ec5a">
compiler/GHC/Core/Unfold.hs
</a>
</li>
<li class="file-stats">
<a href="#1a7aba0daeafab195716dd25432479804a55ab60">
compiler/GHC/Core/Utils.hs
</a>
</li>
<li class="file-stats">
<a href="#bbf06eb5d4f0db7bc3213b84b9f5822710ff7be8">
compiler/GHC/CoreToIface.hs
</a>
</li>
<li class="file-stats">
<a href="#d79a8a61508cb6c5f38a23ab2b691bb77306f672">
compiler/GHC/CoreToStg.hs
</a>
</li>
<li class="file-stats">
<a href="#a5d27de4e3111a69f69902c65ecf7b3379f7c49a">
compiler/GHC/CoreToStg/Prep.hs
</a>
</li>
<li class="file-stats">
<a href="#515e45714efa1079dede946c7258fc0d66d9bd35">
compiler/GHC/Driver/Config/CoreToStg/Prep.hs
</a>
</li>
<li class="file-stats">
<a href="#e65e7bbfc24f8830a20082bfc50f6d16e613cbeb">
compiler/GHC/Driver/DynFlags.hs
</a>
</li>
<li class="file-stats">
<a href="#2e5692f568fd7b67a6b172e2a60469da8392508c">
compiler/GHC/Driver/Flags.hs
</a>
</li>
<li class="file-stats">
<a href="#774d88050336ef660c7a219fb06c480c2fc639bc">
compiler/GHC/Driver/Session.hs
</a>
</li>
<li class="file-stats">
<a href="#079d6b28856775716c78fdd4a4b35bb45a59002c">
compiler/GHC/Iface/Syntax.hs
</a>
</li>
<li class="file-stats">
<a href="#f2b2b84d138b362920ab9f144f58bf16254aab64">
compiler/GHC/Iface/Type.hs
</a>
</li>
<li class="file-stats">
<a href="#06ff7bac58fd8cfe0c17b81963b03f4cce86a065">
compiler/GHC/IfaceToCore.hs
</a>
</li>
<li class="file-stats">
<a href="#2f341f858154eb8e1900d5bd92a156b13ddd06f3">
compiler/GHC/StgToCmm/Bind.hs
</a>
</li>
<li class="file-stats">
<a href="#b7b1f615b91c84c9a77878634ec8fb91a564db8b">
compiler/GHC/StgToCmm/Env.hs
</a>
</li>
<li class="file-stats">
<a href="#77c485508ade5a11428d9fce17204d33c5825722">
compiler/GHC/StgToCmm/Expr.hs
</a>
</li>
<li class="file-stats">
<a href="#2822d6defa206d9f39e5b5c6318c7b011dfc5b5a">
compiler/GHC/StgToJS/Utils.hs
</a>
</li>
<li class="file-stats">
<a href="#5ed3ecf19a26af612b8100b2639f8e153f580fe9">
compiler/GHC/Tc/TyCl/Utils.hs
</a>
</li>
</ul>
<h5 style="margin-top: 10px; margin-bottom: 10px; font-size: 0.875rem;">
The diff was not included because it is too large.
</h5>
</div>
<div class="footer" style="margin-top: 10px;">
<p style="font-size: small; color: #737278;">
—
<br>
<a href="https://gitlab.haskell.org/ghc/ghc/-/compare/b3ed94ae0fef38b7f678f879dcdb4e67a04537a7...6d0d74cd0ea03fcf8a75f3e3aa2dd0e226209afc">View it on GitLab</a>.
<br>
You're receiving this email because of your account on <a target="_blank" rel="noopener noreferrer" href="https://gitlab.haskell.org">gitlab.haskell.org</a>. <a href="https://gitlab.haskell.org/-/profile/notifications" target="_blank" rel="noopener noreferrer" class="mng-notif-link">Manage all notifications</a> · <a href="https://gitlab.haskell.org/help" target="_blank" rel="noopener noreferrer" class="help-link">Help</a>
</p>
</div>
</body>
</html>