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<h3>
Simon Jakobi pushed to branch wip/T17978
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/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/b2dfb01df4e0511f41ff002558cb753bde9d0ba3">b2dfb01d</a></strong>
<div>
<span>by Simon Jakobi</span>
<i>at 2020-04-02T19:21:50+02:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Combine STG free variable traversals
Closes #17978.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/04c40d8ebd44bfe6c2a0269bc1328037fe4f209e">04c40d8e</a></strong>
<div>
<span>by Simon Jakobi</span>
<i>at 2020-04-03T15:55:17+02:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Remove the STG binds forcing step
With a single pass over the bindings, this shouldn't be necessary any more.
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
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<a href="#182d6a315e784018aa9c8b2ad736036b97bd5d48">
compiler/GHC/Core.hs
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<li class="file-stats">
<a href="#448d7f6e0151c2014de38dead3a902f511c45b75">
compiler/GHC/Core/FVs.hs
</a>
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<li class="file-stats">
<a href="#9e2ce77a946950b2d19d75c55f671c048a5645bd">
compiler/GHC/Core/Op/OccurAnal.hs
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<li class="file-stats">
<a href="#e3fe84599ec044fc7aacb062dada32b067732fc8">
compiler/GHC/Core/Op/Simplify.hs
</a>
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<li class="file-stats">
<a href="#b73ea2c5744c45878c8939cf97da70308baa7e48">
compiler/GHC/Core/Op/Simplify/Utils.hs
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<a href="#d01de95d8c71d4dec6a9a59146186e29a5b3fd38">
compiler/GHC/Core/Rules.hs
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<a href="#708fab0a51bd47227233eda4698e750ff6de66e0">
compiler/GHC/Core/Subst.hs
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<li class="file-stats">
<a href="#2811a7297b8aa206197ac1f5dabd0818e3c7ec5a">
compiler/GHC/Core/Unfold.hs
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<a href="#1a7aba0daeafab195716dd25432479804a55ab60">
compiler/GHC/Core/Utils.hs
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<li class="file-stats">
<a href="#a5d27de4e3111a69f69902c65ecf7b3379f7c49a">
compiler/GHC/CoreToStg/Prep.hs
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<li class="file-stats">
<a href="#9a679a2680ef6061397f1987091ea9f96ffe095d">
compiler/GHC/Driver/Main.hs
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<li class="file-stats">
<a href="#774d88050336ef660c7a219fb06c480c2fc639bc">
compiler/GHC/Driver/Session.hs
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<li class="file-stats">
<a href="#d11203a9321005ba51a16d751c86f609d1f18c71">
compiler/GHC/Iface/Tidy.hs
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<li class="file-stats">
<a href="#06ff7bac58fd8cfe0c17b81963b03f4cce86a065">
compiler/GHC/IfaceToCore.hs
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<li class="file-stats">
<a href="#90a56cf7f130d66194a6a61cb5f372eb339ab111">
compiler/GHC/Stg/CSE.hs
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<a href="#305c148430a70c23122a9aed4b8b89d96bf14b46">
compiler/GHC/Stg/DepAnal.hs
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<li class="file-stats">
<a href="#6c6b170dad20b4eedb2e77f6777d30c062f9bcb1">
compiler/GHC/Stg/Pipeline.hs
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<a href="#d09e98aae6ad2eb59d08eac7894b68c0ab820cda">
compiler/GHC/Types/Demand.hs
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<a href="#38110817cdbc9a34d2b80a14070cabc7515c808a">
compiler/GHC/Types/Id/Info.hs
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<a href="#261c0c5029eb34eb7436b087d77314f377ff8223">
compiler/GHC/Types/Id/Make.hs
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<li class="file-stats">
<a href="#b5293b078eb6c44f702248dd629f1afc4cb6a1b1">
compiler/main/SysTools/Terminal.hs
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<li class="file-stats">
<a href="#2a8bedbc781353ca3c4d1e56daba6faa8829aaf3">
compiler/prelude/primops.txt.pp
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<a href="#4f8d5e20ad75b577322cf46f2e146466d905fe43">
compiler/typecheck/TcSplice.hs
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<li class="file-stats">
<a href="#2eeb40f0acd6cb433ebe65e34262040b618908a7">
hadrian/hadrian.cabal
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<a href="#579888c35e9965d115a2349ac57e4ff79e87518f">
hadrian/src/Hadrian/Haskell/Cabal/Parse.hs
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<a href="#fb6173313439af46b3054cb59d8b9287eaae035c">
hadrian/src/Rules/Library.hs
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<a href="#15573cb40fce6bde985c520c7e7647ab4c13453e">
hadrian/stack.yaml
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<a href="#89ed911ca15ec0db941eb82e8d7df8453f4ab713">
includes/stg/MiscClosures.h
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<li class="file-stats">
<a href="#6ca006a5d6dfdfdb97d0dd72db322e3f6eaa6214">
rts/StgMiscClosures.cmm
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<li class="file-stats">
<a href="#6477e10756faf038741e63d1ad499a1df809fe10">
rts/sm/GC.c
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<h5>The diff was not included because it is too large.</h5>
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