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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Hannes Siebenhandl pushed to branch wip/fendor/ghc-iface-sharing-avoid-reserialisation 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/e0099721ce4b2f7f2b5ab21a75160aa212751804">e0099721</a></strong>
<div>
<span> by Andrew Lelechenko </span> <i> at 2024-06-16T17:57:38-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Make flip representation polymorphic, similar to ($) and (&)
CLC proposal: https://github.com/haskell/core-libraries-committee/issues/245
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/118a12921a9ad3049420cdc67deb9c4ea2ccff23">118a1292</a></strong>
<div>
<span> by Alan Zimmerman </span> <i> at 2024-06-16T17:58:15-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>EPA: Add location to Match Pats list
So we can freely modify the pats and the following item spacing will
still be valid when exact printing.
Closes #24862
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/db3433247fd62af09727379355381543b288b63d">db343324</a></strong>
<div>
<span> by Fabricio de Sousa Nascimento </span> <i> at 2024-06-17T10:01:51-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>compiler: Rejects RULES whose LHS immediately fails to type-check
Fixes GHC crashing on `decomposeRuleLhs` due to ignoring coercion values. This
happens when we have a RULE that does not type check, and enable
`-fdefer-type-errors`. We prevent this to happen by rejecting RULES with an
immediately LHS type error.
Fixes #24026
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e7a956623b7d71e50fa86fee83459d2611c423b8">e7a95662</a></strong>
<div>
<span> by Dylan Thinnes </span> <i> at 2024-06-17T10:02:35-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Add hscTypecheckRenameWithDiagnostics, for HLS (#24996)
Use runHsc' in runHsc so that both functions can't fall out of sync
We're currently copying parts of GHC code to get structured warnings
in HLS, so that we can recreate `hscTypecheckRenameWithDiagnostics`
locally. Once we get this function into GHC we can drop the copied code
in future versions of HLS.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/13320ff25a59596c01a17d5990c87382cd8d77c8">13320ff2</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-06-17T17:31:34+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Improve sharing of duplicated values in `ModIface`, fixes #24723
As a `ModIface` often contains duplicated values that are not
necessarily shared, we improve sharing by serialising the `ModIface`
to an in-memory byte array. Serialisation uses deduplication tables, and
deserialisation implicitly shares duplicated values.
This helps reducing the peak memory usage while compiling in
`--make` mode. The peak memory usage is especially smaller when
generating interface files with core expressions
(`-fwrite-if-simplified-core`).
On agda, this reduces the peak memory usage:
* `2.2 GB` to `1.9 GB` for a ghci session.
On `lib:Cabal`, we report:
* `570 MB` to `500 MB` for a ghci session
* `790 MB` to `667 MB` for compiling `lib:Cabal` with ghc
There is a small impact on execution time, around 2% on the agda code
base.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/52e2537a0c24ff3a75a808403a63313c809c355d">52e2537a</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-06-17T17:31:37+02:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Avoid unneccessarily re-serialising the `ModIface`
To reduce memory usage of `ModIface`, we serialise `ModIface` to an
in-memory byte array, which implicitly shares duplicated values.
This serialised byte array can be reused to avoid work when we actually
write the `ModIface` to disk.
We introduce a new field to `ModIface` which allows us to save the byte
array, and write it direclty to disk if the `ModIface` wasn't changed
after the initial serialisation.
This requires us to change absolute offsets, for example to jump to the
deduplication table for `Name` or `FastString` with relative offsets, as
the deduplication byte array doesn't contain header information, such as
fingerprints.
To allow us to dump the binary blob to disk, we need to replace all
absolute offsets with relative ones.
We introduce additional helpers for `ModIface` binary serialisation, which
construct relocatable binary blobs. We say the binary blob is relocatable,
if the binary representation can be moved and does not contain any
absolute offsets.
Further, we introduce new primitives for `Binary` that allow to create
relocatable binaries, such as `forwardGetRel` and `forwardPutRel`.
-------------------------
Metric Decrease:
MultiLayerModulesDefsGhcWithCore
Metric Increase:
MultiComponentModules
MultiLayerModules
T10421
T12150
T12234
T12425
T13035
T13253-spj
T13701
T13719
T14697
T15703
T16875
T18698b
T18140
T18304
T18698a
T18730
T18923
T20049
T24582
T5837
T6048
T9198
T9961
mhu-perf
-------------------------
These metric increases may look bad, but they are all completely benign,
we simply allocate 1 MB per module for `shareIface`. As this allocation
is quite quick, it has a negligible impact on run-time performance.
In fact, the performance difference wasn't measurable on my local
machine. Reducing the size of the pre-allocated 1 MB buffer avoids these
test failures, but also requires us to reallocate the buffer if the
interface file is too big. These reallocations *did* have an impact on
performance, which is why I have opted to accept all these metric
increases, as the number of allocated bytes is merely a guidance.
This 1MB allocation increase causes a lot of tests to fail that
generally have a low allocation number. E.g., increasing from 40MB to
41MB is a 2.5% increase.
In particular, the tests T12150, T13253-spj, T18140, T18304, T18698a,
T18923, T20049, T24582, T5837, T6048, and T9961 only fail on i386-darwin
job, where the number of allocated bytes seems to be lower than in other
jobs.
The tests T16875 and T18698b fail on i386-linux for the same reason.
</pre>
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<h4 style="margin-top: 10px; margin-bottom: 10px;">
30 changed files:
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<a href="#d0d96a6d03668aeab20ebe05e2c4ccb798c7e64c">
compiler/GHC.hs
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compiler/GHC/Driver/Env.hs
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compiler/GHC/Driver/Main.hs
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compiler/GHC/Hs/Expr.hs
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compiler/GHC/Hs/Utils.hs
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compiler/GHC/HsToCore/Arrows.hs
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compiler/GHC/HsToCore/Binds.hs
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compiler/GHC/HsToCore/Expr.hs
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compiler/GHC/HsToCore/Match.hs
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compiler/GHC/HsToCore/Pmc/Desugar.hs
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compiler/GHC/HsToCore/Quote.hs
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compiler/GHC/HsToCore/Ticks.hs
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compiler/GHC/Iface/Binary.hs
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compiler/GHC/Iface/Ext/Ast.hs
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compiler/GHC/Iface/Ext/Binary.hs
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compiler/GHC/Iface/Ext/Fields.hs
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compiler/GHC/Iface/Load.hs
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compiler/GHC/Iface/Make.hs
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compiler/GHC/Iface/Recomp.hs
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compiler/GHC/Iface/Rename.hs
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compiler/GHC/Parser.y
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compiler/GHC/Parser/Annotation.hs
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compiler/GHC/Parser/PostProcess.hs
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compiler/GHC/Rename/Bind.hs
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compiler/GHC/Rename/Expr.hs
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compiler/GHC/Rename/HsType.hs
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compiler/GHC/Rename/Module.hs
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compiler/GHC/Rename/Utils.hs
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compiler/GHC/Tc/Deriv/Functor.hs
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compiler/GHC/Tc/Deriv/Generate.hs
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The diff was not included because it is too large.
</h5>
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