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<h3>
Marge Bot pushed to branch wip/marge_bot_batch_merge_job
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/72a87fbc7a95c012be260d1a14374e2b06ed0a36">72a87fbc</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-12-01T19:57:41-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Move core flattening algorithm to Core.Unify
This sets the stage for a later change, where this
algorithm will be needed from GHC.Core.InstEnv.
This commit also splits GHC.Core.Map into
GHC.Core.Map.Type and GHC.Core.Map.Expr,
in order to avoid module import cycles
with GHC.Core.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0dd45d0adbade7eaae973b09b4d0ff1acb1479b8">0dd45d0a</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-12-01T19:57:41-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Bump the # of commits searched for perf baseline
The previous value of 75 meant that a feature branch with
more than 75 commits would get spurious CI passes.
This affects #18692, but does not fix that ticket, because
if a baseline cannot be found, we should fail, not succeed.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8bb52d9186655134e3e06b4dc003e060379f5417">8bb52d91</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-12-01T19:57:41-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Remove flattening variables
This patch redesigns the flattener to simplify type family applications
directly instead of using flattening meta-variables and skolems. The key new
innovation is the CanEqLHS type and the new CEqCan constraint (Ct). A CanEqLHS
is either a type variable or exactly-saturated type family application; either
can now be rewritten using a CEqCan constraint in the inert set.
Because the flattener no longer reduces all type family applications to
variables, there was some performance degradation if a lengthy type family
application is now flattened over and over (not making progress). To
compensate, this patch contains some extra optimizations in the flattener,
leading to a number of performance improvements.
Close #18875.
Close #18910.
There are many extra parts of the compiler that had to be affected in writing
this patch:
* The family-application cache (formerly the flat-cache) sometimes stores
coercions built from Given inerts. When these inerts get kicked out, we must
kick out from the cache as well. (This was, I believe, true previously, but
somehow never caused trouble.) Kicking out from the cache requires adding a
filterTM function to TrieMap.
* This patch obviates the need to distinguish "blocking" coercion holes from
non-blocking ones (which, previously, arose from CFunEqCans). There is thus
some simplification around coercion holes.
* Extra commentary throughout parts of the code I read through, to preserve
the knowledge I gained while working.
* A change in the pure unifier around unifying skolems with other types.
Unifying a skolem now leads to SurelyApart, not MaybeApart, as documented
in Note [Binding when looking up instances] in GHC.Core.InstEnv.
* Some more use of MCoercion where appropriate.
* Previously, class-instance lookup automatically noticed that e.g. C Int was
a "unifier" to a target [W] C (F Bool), because the F Bool was flattened to
a variable. Now, a little more care must be taken around checking for
unifying instances.
* Previously, tcSplitTyConApp_maybe would split (Eq a => a). This is silly,
because (=>) is not a tycon in Haskell. Fixed now, but there are some
knock-on changes in e.g. TrieMap code and in the canonicaliser.
* New function anyFreeVarsOf{Type,Co} to check whether a free variable
satisfies a certain predicate.
* Type synonyms now remember whether or not they are "forgetful"; a forgetful
synonym drops at least one argument. This is useful when flattening; see
flattenView.
* The pattern-match completeness checker invokes the solver. This invocation
might need to look through newtypes when checking representational equality.
Thus, the desugarer needs to keep track of the in-scope variables to know
what newtype constructors are in scope. I bet this bug was around before but
never noticed.
* Extra-constraints wildcards are no longer simplified before printing.
See Note [Do not simplify ConstraintHoles] in GHC.Tc.Solver.
* Whether or not there are Given equalities has become slightly subtler.
See the new HasGivenEqs datatype.
* Note [Type variable cycles in Givens] in GHC.Tc.Solver.Canonical
explains a significant new wrinkle in the new approach.
* See Note [What might match later?] in GHC.Tc.Solver.Interact, which
explains the fix to #18910.
* The inert_count field of InertCans wasn't actually used, so I removed
it.
Though I (Richard) did the implementation, Simon PJ was very involved
in design and review.
This updates the Haddock submodule to avoid #18932 by adding
a type signature.
-------------------------
Metric Decrease:
T12227
T5030
T9872a
T9872b
T9872c
Metric Increase:
T9872d
-------------------------
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d66660ba4c491f9937a1a959b009d90f08a4fbee">d66660ba</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-12-01T19:57:41-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Rename the flattener to become the rewriter.
Now that flattening doesn't produce flattening variables,
it's not really flattening anything: it's rewriting. This
change also means that the rewriter can no longer be confused
the core flattener (in GHC.Core.Unify), which is sometimes used
during type-checking.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/add0aeaefd4d823d31315564e924ce8c018fb69e">add0aeae</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-01T19:58:17-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts: Introduce mmapAnonForLinker
Previously most of the uses of mmapForLinker were mapping anonymous
memory, resulting in a great deal of unnecessary repetition. Factor this
out into a new helper.
Also fixes a few places where error checking was missing or suboptimal.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/97d71646ddf3814de62573100ed0b224d1588cbc">97d71646</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-01T19:58:17-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/linker: Introduce munmapForLinker
Consolidates munmap calls to ensure consistent error handling.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d8872af08d205c3067371d56200e68cf2f0c1ffc">d8872af0</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-01T19:58:18-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/Linker: Introduce Windows implementations for mmapForLinker, et al.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c35d0e03514ce111ff8265426a7b911456984f50">c35d0e03</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-01T19:58:18-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/m32: Introduce NEEDS_M32 macro
Instead of relying on RTS_LINKER_USE_MMAP
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/41c64eb5db50c80e110e47b7ab1c1ee18dada46b">41c64eb5</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-01T19:58:18-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/linker: Use m32 to allocate symbol extras in PEi386
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e0b08c5f445f70381c854f78913489685feb224e">e0b08c5f</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-03T13:01:47-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">gitlab-ci: Fix copy-paste error
Also be more consistent in quoting.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/33ec3a0600fe8c009ab8ed6d86941a8fd88fb033">33ec3a06</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-12-03T23:11:31-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">gitlab-ci: Run linters through ci.sh
Ensuring that the right toolchain is used.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/ad28aa1300301ad577ba32f0712d4ace6c880014">ad28aa13</a></strong>
<div>
<span>by Shayne Fletcher</span>
<i>at 2020-12-04T20:15:31-05:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix bad span calculations of post qualified imports
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
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<li class="file-stats">
<a href="#587d266bb27a4dc3022bbed44dfa19849df3044c">
.gitlab-ci.yml
</a>
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<li class="file-stats">
<a href="#157f7634c25bc6366cb7c9c9edb48e819dce38db">
.gitlab/ci.sh
</a>
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<li class="file-stats">
<a href="#806448db91cc2906ebcc088107220a663d3d43eb">
compiler/GHC/Cmm/CommonBlockElim.hs
</a>
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<li class="file-stats">
<a href="#4fbb1c5f251c38fc01fcde693420ee6d02df7e45">
compiler/GHC/Cmm/Dataflow/Label.hs
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<a href="#783e5dae6e86931f06700fc088fb7d48c8a07386">
compiler/GHC/Core/Coercion.hs
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<a href="#b0ab2032bd0c006bb9cda1e5433173de35930f53">
compiler/GHC/Core/Coercion.hs-boot
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<a href="#f10ed7a2470454dfdd8691a08beba67d8b78ee70">
compiler/GHC/Core/Coercion/Axiom.hs
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<a href="#975dc08a8e7942b32d621f617d5a9c1b668601dd">
compiler/GHC/Core/Coercion/Opt.hs
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<a href="#91648438362e5a35363d2bb7abb04016dedd7d7e">
compiler/GHC/Core/FamInstEnv.hs
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<a href="#5596bb0f228bd2a308c4391df97375ae879430a8">
compiler/GHC/Core/InstEnv.hs
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<a href="#640612f2fdc707ac7ee74f4165a7b86f38aa6249">
<span class="new-file">
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compiler/GHC/Core/Map/Expr.hs
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<a href="#691eec62dc293d0881c314b38b7363dc88b44c59">
compiler/GHC/Core/Map.hs
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compiler/GHC/Core/Map/Type.hs
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<a href="#446b4afbe6836b950115a619acea24ddde19dc90">
compiler/GHC/Core/Opt/CSE.hs
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<a href="#039e8f5676356ef05c90af828aae48aac7296e47">
compiler/GHC/Core/TyCo/FVs.hs
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<a href="#578c7c3857d66d963736ff6742f3433a0e8d01b7">
compiler/GHC/Core/TyCo/Rep.hs
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<a href="#4aad0050db1a8a20db8bbca149111de99cb299c9">
compiler/GHC/Core/TyCon.hs
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<a href="#d1a980a3e0f207c148bb3ab404696977015bcc56">
compiler/GHC/Core/TyCon/Env.hs
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<a href="#84c9d3ba34173297e7d7747e02caa2e004b164fc">
compiler/GHC/Core/Type.hs
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<a href="#89a2e0e1a3095c7a42b10f2819049908908080e8">
compiler/GHC/Core/Unify.hs
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<a href="#2fefe3125c649bc5377b06a7cca18e785855b79c">
compiler/GHC/Data/Bag.hs
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<a href="#f4ae6618b39d5ee4af8302b821aa7e38097a84b7">
compiler/GHC/Data/Maybe.hs
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<a href="#87e780e9b5d14cf4e8a52bb125fc352fa8a1d4be">
compiler/GHC/Data/TrieMap.hs
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<a href="#2e5692f568fd7b67a6b172e2a60469da8392508c">
compiler/GHC/Driver/Flags.hs
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compiler/GHC/Driver/Session.hs
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compiler/GHC/HsToCore/Monad.hs
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compiler/GHC/HsToCore/Pmc/Solver.hs
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<a href="#6983b6dc1a4f225d4e72180ad45d8484d9d32931">
compiler/GHC/HsToCore/Pmc/Solver/Types.hs
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<a href="#b2fd0f5f3e0bc9dcc507931c0b7388bf10e925c2">
compiler/GHC/HsToCore/Types.hs
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<a href="#1cf39038e57acc2a80cb5fb3fef9733e8e37b8fb">
compiler/GHC/Iface/Ext/Utils.hs
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<a href="#bf951467d4a9aa443cb109cb4c84a2891945649b">
compiler/GHC/Parser.y
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<h5>The diff was not included because it is too large.</h5>
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