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<h3>
Simon Peyton Jones pushed to branch wip/T17917
at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4>
Commits:
</h4>
<ul>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f024b6e385bd1448968b7bf20de05f655c815bae">f024b6e3</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-03-30T12:48:39+02:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Expect T4267 to pass
Since 54250f2d8de910b094070c1b48f086030df634b1 we expected T4267 to
fail, but it passes on CI.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/57b888c0e90be7189285a6b078c30b26d0923809">57b888c0</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-03-31T10:54:20-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Require GHC 8.8 as the minimum compiler for bootstrapping
This allows us to remove several bits of CPP that are either always
true or no longer reachable. As an added bonus, we no longer need to
worry about importing `Control.Monad.Fail.fail` qualified to avoid
clashing with `Control.Monad.fail`, since the latter is now the same
as the former.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/33f095511a8fce4c945bbcd4feb3910c854dcb61">33f09551</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-03-31T10:54:57-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add regression test for #17963
The panic in #17963 happened to be fixed by commit
e3c374cc5bd7eb49649b9f507f9f7740697e3f70. This patch adds a
regression test to ensure that it remains fixed.
Fixes #17963.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/09a36e80ecaefcfb60eccda98bd06461d0aeca70">09a36e80</a></strong>
<div>
<span>by Ömer Sinan Ağacan</span>
<i>at 2020-03-31T10:55:37-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Simplify stderrSupportsAnsiColors
The combinator andM is used only once, and the code is shorter and
simpler if you inline it.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/95bccdd034ce4dd2d1bc36db9f1ba5e172550249">95bccdd0</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-03-31T10:56:19-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">base: Ensure that encoding global variables aren't inlined
As noted in #17970, these (e.g. `getFileSystemEncoding` and
`setFileSystemEncoding`) previously had unfoldings, which would
break their global-ness.
While not strictly necessary, I also add a NOINLINE on
`initLocaleEncoding` since it is used in `System.IO`, ensuring that we
only system's query the locale encoding once.
Fixes #17970.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/982aaa837aed564ae9b418cda8e97d4facff8fb8">982aaa83</a></strong>
<div>
<span>by Andreas Klebinger</span>
<i>at 2020-03-31T10:56:55-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Update hadrian index revision.
Required in order to build hadrian using ghc-8.10
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4b9c586472bf99425f7bbcf346472d7c54f05028">4b9c5864</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-03-31T10:57:32-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">integer-gmp: Bump version and add changelog entry
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9b39f2e6f63ae50cedd96eaf49146de8ed00fbc8">9b39f2e6</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-04-01T01:20:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Clean up "Eta reduction for data families" Notes
Before, there were two distinct Notes named
"Eta reduction for data families". This renames one of them to
"Implementing eta reduction for data families" to disambiguate the
two and fixes references in other parts of the codebase to ensure
that they are pointing to the right place.
Fixes #17313.
[ci skip]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7627eab5dd882eb6f1567e3ae95c6c770830a5eb">7627eab5</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-04-01T01:20:38-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix the changelog/@since information for hGetContents'/getContents'/readFile'
Fixes #17979.
[ci skip]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0002db1bf436cbd32f97b659a52b1eee4e8b21db">0002db1b</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-04-01T01:21:27-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Kill wORDS_BIGENDIAN and replace it with platformByteOrder (#17957)
Metric Decrease:
T13035
T1969
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7b21717907a741b56513f5e1fa1ebceecf971613">7b217179</a></strong>
<div>
<span>by Sebastian Graf</span>
<i>at 2020-04-01T15:03:24-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">PmCheck: Adjust recursion depth for inhabitation test
In #17977, we ran into the reduction depth limit of the typechecker.
That was only a symptom of a much broader issue: The recursion depth
of the coverage checker for trying to instantiate strict fields in the
`nonVoid` test was far too high (100, the `defaultMaxTcBound`).
As a result, we were performing quite poorly on `T17977`.
Short of a proper termination analysis to prove emptyness of a type,
we just arbitrarily default to a much lower recursion limit of 3.
Fixes #17977.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3c09f636a459f50119bfbb5bf798b9a9e19eb464">3c09f636</a></strong>
<div>
<span>by Andreas Klebinger</span>
<i>at 2020-04-01T15:03:59-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Make hadrian pass on the no-colour setting to GHC.
Fixes #17983.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b943b25d0786da64031ac63ddf9b4574182057bb">b943b25d</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-04-02T01:45:58-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Re-engineer the binder-swap transformation
The binder-swap transformation is implemented by the occurrence
analyser -- see Note [Binder swap] in OccurAnal. However it had
a very nasty corner in it, for the case where the case scrutinee
was a GlobalId. This led to trouble and hacks, and ultimately
to #16296.
This patch re-engineers how the occurrence analyser implements
the binder-swap, by actually carrying out a substitution rather
than by adding a let-binding. It's all described in
Note [The binder-swap substitution].
I did a few other things along the way
* Fix a bug in StgCse, which could allow a loop breaker to be CSE'd
away. See Note [Care with loop breakers] in StgCse. I think it can
only show up if occurrence analyser sets up bad loop breakers, but
still.
* Better commenting in SimplUtils.prepareAlts
* A little refactoring in CoreUnfold; nothing significant
e.g. rename CoreUnfold.mkTopUnfolding to mkFinalUnfolding
* Renamed CoreSyn.isFragileUnfolding to hasCoreUnfolding
* Move mkRuleInfo to CoreFVs
We observed respectively 4.6% and 5.9% allocation decreases for the following
tests:
Metric Decrease:
T9961
haddock.base
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/42d68364f66846969edf029f878875c10cdfe0b2">42d68364</a></strong>
<div>
<span>by Sebastian Graf</span>
<i>at 2020-04-02T01:46:34-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Preserve precise exceptions in strictness analysis
Fix #13380 and #17676 by
1. Changing `raiseIO#` to have `topDiv` instead of `botDiv`
2. Give it special treatment in `Simplifier.Util.mkArgInfo`, treating it
as if it still had `botDiv`, to recover dead code elimination.
This is the first commit of the plan outlined in
https://gitlab.haskell.org/ghc/ghc/-/merge_requests/2525#note_260886.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0a88dd11594b8d8fd20500d026e657a5f99dfdd2">0a88dd11</a></strong>
<div>
<span>by Ömer Sinan Ağacan</span>
<i>at 2020-04-02T01:47:25-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix a pointer format string in RTS
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/5beac042b995b055a66bc16be536d9e920f6864d">5beac042</a></strong>
<div>
<span>by Ömer Sinan Ağacan</span>
<i>at 2020-04-02T01:48:05-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Remove unused closure stg_IND_direct
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/88f38b03025386f0f1e8f5861eed67d80495168a">88f38b03</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-04-02T01:48:42-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Session: Memoize stderrSupportsAnsiColors
Not only is this a reasonable efficiency measure but it avoids making
reentrant calls into ncurses, which is not thread-safe. See #17922.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/27740f24cb70fc14b00c1212c06642a144a6117d">27740f24</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-04-02T01:49:21-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Make Hadrian build with Cabal-3.2
GHC 8.10 ships with `Cabal-3.2.0.0`, so it would be convenient to
make Hadrian supporting building against 3.2.* instead of having to
rebuild the entirety of `Cabal-3.0.0.0`. There is one API change in
`Cabal-3.2.*` that affects Hadrian: the `synopsis` and `description`
functions now return `ShortText` instead of `String`. Since Hadrian
manipulates these `String`s in various places, I found that the
simplest fix was to use CPP to convert `ShortText` to `String`s
where appropriate.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4980200255dabf59ae537f10c55d19ef1a00bbdd">49802002</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-04-02T01:50:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Update Stack resolver for hadrian/build-stack
Broken by 57b888c0e90be7189285a6b078c30b26d0923809
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/30a63e79c65b023497af4fe2347149382c71829d">30a63e79</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-04-02T01:50:36-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix two ASSERT buglets in reifyDataCon
Two `ASSERT`s in `reifyDataCon` were always using `arg_tys`, but
`arg_tys` is not meaningful for GADT constructors. In fact, it's
worse than non-meaningful, since using `arg_tys` when reifying a
GADT constructor can lead to failed `ASSERT`ions, as #17305
demonstrates.
This patch applies the simplest possible fix to the immediate
problem. The `ASSERT`s now use `r_arg_tys` instead of `arg_tys`, as
the former makes sure to give something meaningful for GADT
constructors. This makes the panic go away at the very least. There
is still an underlying issue with the way the internals of
`reifyDataCon` work, as described in
https://gitlab.haskell.org/ghc/ghc/issues/17305#note_227023, but we
leave that as future work, since fixing the underlying issue is
much trickier (see
https://gitlab.haskell.org/ghc/ghc/issues/17305#note_227087).
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9a18e3220ca0ab162a9f1047479f83fb7a327bfa">9a18e322</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-04-02T10:22:14+01:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Avoid useless w/w split
This patch is just a tidy-up for the post-strictness-analysis
worker wrapper split. Consider
f x = x
Strictnesss analysis does not lead to a w/w split, so the
obvious thing is to leave it 100% alone. But actually, because
the RHS is small, we ended up adding a StableUnfolding for it.
There is some reason to do this if we choose /not/ do to w/w
on the grounds that the function is small. See
Note [Don't w/w inline small non-loop-breaker things]
But there is no reason if we would not have done w/w anyway.
This patch just moves the conditional to later. Easy.
This does move soem -ddump-simpl printouts around a bit.
I also discovered that the previous code was overwritten an
InlineCompulsory with InlineStable, which is utterly wrong. That in
turn meant that some default methods (marked InlineCompulsory)
were getting their InlineCompulsory squashed. This patch fixes
that bug --- but of course that does mean a bit more inlining!
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
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<a href="#587d266bb27a4dc3022bbed44dfa19849df3044c">
.gitlab-ci.yml
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<a href="#47cba74ae8965f1665cd11bf2b023760ea27594e">
compiler/GHC/Cmm/Info.hs
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<a href="#f9f29a5a64a0b66967f0a7c538dbf8ad06a9f5bb">
compiler/GHC/Cmm/Utils.hs
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compiler/GHC/CmmToC.hs
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compiler/GHC/Core.hs
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compiler/GHC/Core/Coercion.hs
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compiler/GHC/Core/Coercion/Axiom.hs
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compiler/GHC/Core/FVs.hs
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compiler/GHC/Core/FamInstEnv.hs
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compiler/GHC/Core/Lint.hs
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compiler/GHC/Core/Subst.hs
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compiler/GHC/Core/Unify.hs
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compiler/GHC/Core/Utils.hs
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compiler/GHC/CoreToStg/Prep.hs
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compiler/GHC/Driver/Session.hs
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compiler/GHC/HsToCore/PmCheck/Oracle.hs
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compiler/GHC/Iface/Tidy.hs
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compiler/GHC/IfaceToCore.hs
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compiler/GHC/Llvm/Types.hs
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