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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/3b51995c158fe19d48839b92cf1ff78ce7825ce4">3b51995c</a></strong>
<div>
<span> by Andrei Borzenkov </span> <i> at 2024-05-07T14:39:40-04:00 </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;'>Rename Solo# data constructor to MkSolo# (#24673)
- data Solo# a = (# a #)
+ data Solo# a = MkSolo# a
And `(# foo #)` syntax now becomes just a syntactic
sugar for `MkSolo# a`.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4d59abf295cd371448f22c1724b955dce4974302">4d59abf2</a></strong>
<div>
<span> by Arsen Arsenović </span> <i> at 2024-05-07T14:40:24-04:00 </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 the cmm_cpp_is_gcc predicate to the testsuite
A future C-- test called T24474-cmm-override-g0 relies on the
GCC-specific behaviour of -g3 implying -dD, which, in turn, leads to it
emitting #defines past the preprocessing stage. Clang, at least, does
not do this, so the test would fail if ran on Clang.
As the behaviour here being tested is ``-optCmmP-g3'' undoing effects of
the workaround we apply as a fix for bug #24474, and the workaround was
for GCC-specific behaviour, the test needs to be marked as fragile on
other compilers.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/25b0b40467d0a12601497117c0ad14e1fcab0b74">25b0b404</a></strong>
<div>
<span> by Arsen Arsenović </span> <i> at 2024-05-07T14:40:24-04:00 </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;'>Split out the C-- preprocessor, and make it pass -g0
Previously, C-- was processed with the C preprocessor program. This
means that it inherited flags passed via -optc. A flag that is somewhat
often passed through -optc is -g. At certain -g levels (>=2), GCC
starts emitting defines *after* preprocessing, for the purposes of
debug info generation. This is not useful for the C-- compiler, and, in
fact, causes lexer errors. We can suppress this effect (safely, if
supported) via -g0.
As a workaround, in older versions of GCC (<=10), GCC only emitted
defines if a certain set of -g*3 flags was passed. Newer versions check
the debug level. For the former, we filter out those -g*3 flags and,
for the latter, we specify -g0 on top of that.
As a compatible and effective solution, this change adds a C--
preprocessor distinct from the C compiler and preprocessor, but that
keeps its flags. The command line produced for C-- preprocessing now
looks like:
$pgmCmmP $optCs_without_g3 $g0_if_supported $optCmmP
Closes: https://gitlab.haskell.org/ghc/ghc/-/issues/24474
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9b4129a580e6c1d18197ef2ed3a8b89d52a2b133">9b4129a5</a></strong>
<div>
<span> by Andreas Klebinger </span> <i> at 2024-05-08T13:24:20-04:00 </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;'>-fprof-late: Only insert cost centres on functions/non-workfree cafs.
They are usually useless and doing so for data values comes with
a large compile time/code size overhead.
Fixes #24103
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/259b63d32e77e935a9a4f54f6823f89a51fa3fc5">259b63d3</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2024-05-08T13:24:57-04:00 </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;'>Simplifier: Preserve OccInfo on DataAlt fields when case binder is dead (#24770)
See the adjusted `Note [DataAlt occ info]`.
This change also has a positive repercussion on
`Note [Combine case alts: awkward corner]`.
Fixes #24770.
We now try not to call `dataConRepStrictness` in `adjustFieldsIdInfo` when all
fields are lazy anyway, leading to a 2% ghc/alloc decrease in T9675.
Metric Decrease:
T9675
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/31b28cdb4adde2ab14adb153afa817ef9197830f">31b28cdb</a></strong>
<div>
<span> by Sebastian Graf </span> <i> at 2024-05-08T13:24:57-04:00 </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;'>Kill seqRule, discard dead seq# in Prep (#24334)
Discarding seq#s in Core land via `seqRule` was problematic; see #24334.
So instead we discard certain dead, discardable seq#s in Prep now.
See the updated `Note [seq# magic]`.
This fixes the symptoms of #24334.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b2682534f1a707b6b3a955837ffd4d0e33d408d2">b2682534</a></strong>
<div>
<span> by Rodrigo Mesquita </span> <i> at 2024-05-10T01:47:51-04:00 </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;'>Document NcgImpl methods
Fixes #19914
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4d3acbcf4c78636afd79883ad021ed6f7ea92a75">4d3acbcf</a></strong>
<div>
<span> by Zejun Wu </span> <i> at 2024-05-10T01:48:28-04:00 </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 renamer to be more flexible with parens in the LHS of the rules
We used to reject LHS like `(f a) b` in RULES and requires it to be written as
`f a b`. It will be handy to allow both as the expression may be more
readable with extra parens in some cases when infix operator is involved.
Espceially when TemplateHaskell is used, extra parens may be added out of
user's control and result in "valid" rules being rejected and there
are not always ways to workaround it.
Fixes #24621
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/ab840ce6f83a74f36dac939d087b69f97404399a">ab840ce6</a></strong>
<div>
<span> by Ben Gamari </span> <i> at 2024-05-10T01:49:04-04:00 </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;'>IPE: Eliminate dependency on Read
Instead of encoding the closure type as decimal string we now simply
represent it as an integer, eliminating the need for `Read` in
`GHC.Internal.InfoProv.Types.peekInfoProv`.
Closes #24504.
-------------------------
Metric Decrease:
T24602_perf_size
size_hello_artifact
-------------------------
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/a9979f55d0f688fabd25ee318e44b9addd904988">a9979f55</a></strong>
<div>
<span> by Cheng Shao </span> <i> at 2024-05-10T01:49:43-04:00 </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;'>testsuite: fix testwsdeque with recent clang
This patch fixes compilation of testwsdeque.c with recent versions of
clang, which will fail with the error below:
```
testwsdeque.c:95:33: error:
warning: format specifies type 'long' but the argument has type 'void *' [-Wformat]
95 | barf("FAIL: %ld %d %d", p, n, val);
| ~~~ ^
testwsdeque.c:95:39: error:
warning: format specifies type 'int' but the argument has type 'StgWord' (aka 'unsigned long') [-Wformat]
95 | barf("FAIL: %ld %d %d", p, n, val);
| ~~ ^~~
| %lu
testwsdeque.c:133:42: error:
error: incompatible function pointer types passing 'void (void *)' to parameter of type 'OSThreadProc *' (aka 'void *(*)(void *)') [-Wincompatible-function-pointer-types]
133 | createOSThread(&ids[n], "thief", thief, (void*)(StgWord)n);
| ^~~~~
/workspace/ghc/_build/stage1/lib/../lib/x86_64-linux-ghc-9.11.20240502/rts-1.0.2/include/rts/OSThreads.h:193:51: error:
note: passing argument to parameter 'startProc' here
193 | OSThreadProc *startProc, void *param);
| ^
2 warnings and 1 error generated.
```
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c2b33fc9091c7b30962d88e7144fb8705b881631">c2b33fc9</a></strong>
<div>
<span> by Rodrigo Mesquita </span> <i> at 2024-05-10T01:50:20-04:00 </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;'>Rename pre-processor invocation args
Small clean up. Uses proper names for the various groups of arguments
that make up the pre-processor invocation.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2b1af08b94024c104b54eadd710855e9f8a90fb6">2b1af08b</a></strong>
<div>
<span> by Cheng Shao </span> <i> at 2024-05-10T01:50:55-04:00 </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;'>ghc-heap: fix typo in ghc-heap cbits
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/fc2d6de15c4a578a710cb475f9c258cf47e17756">fc2d6de1</a></strong>
<div>
<span> by Jade </span> <i> at 2024-05-10T21:07:16-04:00 </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;'>Improve performance of Data.List.sort(By)
This patch improves the algorithm to sort lists in base.
It does so using two strategies:
1) Use a four-way-merge instead of the 'default' two-way-merge.
This is able to save comparisons and allocations.
2) Use `(>) a b` over `compare a b == GT` and allow inlining and specialization.
This mainly benefits types with a fast (>).
Note that this *may* break instances with a *malformed* Ord instance
where `a > b` is *not* equal to `compare a b == GT`.
CLC proposal: https://github.com/haskell/core-libraries-committee/issues/236
Fixes #24280
-------------------------
Metric Decrease:
MultiLayerModulesTH_Make
T10421
T13719
T15164
T18698a
T18698b
T1969
T9872a
T9961
T18730
WWRec
T12425
T15703
-------------------------
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/1012e8aae57d1e61ea2f3b39ebe7bfa1ebe2dc0e">1012e8aa</a></strong>
<div>
<span> by Matthew Pickering </span> <i> at 2024-05-10T21:07:52-04:00 </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;'>Revert "ghcup-metadata: Drop output_name field"
This reverts commit ecbf22a6ac397a791204590f94c0afa82e29e79f.
This breaks the ghcup metadata generation on the nightly jobs.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/daff1e30219d136977c71f42e82ccc58c9013cfb">daff1e30</a></strong>
<div>
<span> by Jannis </span> <i> at 2024-05-12T13:38:35-04:00 </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;'>Division by constants optimization
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/413217ba04b999313949b570a9386ca36e8ac82c">413217ba</a></strong>
<div>
<span> by Andreas Klebinger </span> <i> at 2024-05-12T13:39:11-04:00 </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;'>Tidy: Add flag to expose unfoldings if they take dictionary arguments.
Add the flag `-fexpose-overloaded-unfoldings` to be able to control this
behaviour.
For ghc's boot libraries file size grew by less than 1% when it was
enabled. However I refrained from enabling it by default for now.
I've also added a section on specialization more broadly to the users
guide.
-------------------------
Metric Decrease:
MultiLayerModulesTH_OneShot
Metric Increase:
T12425
T13386
hard_hole_fits
-------------------------
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c5d89412dd21a428709c00499dfa611312ad4735">c5d89412</a></strong>
<div>
<span> by Zubin Duggal </span> <i> at 2024-05-13T22:19:53-04:00 </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;'>Don't store a GlobalRdrEnv in `mi_globals` for GHCi.
GHCi only needs the `mi_globals` field for modules imported with
:module +*SomeModule.
It uses this field to make the top level environment in `SomeModule` available
to the repl.
By default, only the first target in the command line parameters is
"star" loaded into GHCi. Other modules have to be manually "star" loaded
into the repl.
Storing the top level GlobalRdrEnv for each module is very wasteful, especially
given that we will most likely never need most of these environments.
Instead we store only the information needed to reconstruct the top level environment
in a module, which is the `IfaceTopEnv` data structure, consisting of all import statements
as well as all top level symbols defined in the module (not taking export lists into account)
When a particular module is "star-loaded" into GHCi (as the first commandline target, or via
an explicit `:module +*SomeModule`, we reconstruct the top level environment on demand using
the `IfaceTopEnv`.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d65bf4a28688028600ef706c0b62275f1fdca628">d65bf4a2</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-13T22:20:30-04:00 </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 perf regression test for `-fwrite-if-simplified-core`
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2c0f8ddbdf351ed84395afa04a2654a7cbe2ad35">2c0f8ddb</a></strong>
<div>
<span> by Andrei Borzenkov </span> <i> at 2024-05-13T22:21:07-04:00 </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;'>Improve pattern to type pattern transformation (23739)
`pat_to_type_pat` function now can handle more patterns:
- TuplePat
- ListPat
- LitPat
- NPat
- ConPat
Allowing these new constructors in type patterns significantly
increases possible shapes of type patterns without `type` keyword.
This patch also changes how lookups in `lookupOccRnConstr` are
performed, because we need to fall back into
types when we didn't find a constructor on data level to perform
`ConPat` to type transformation properly.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/be514bb48629747258416e602c8b00810b3863b0">be514bb4</a></strong>
<div>
<span> by Cheng Shao </span> <i> at 2024-05-13T22:21:43-04:00 </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;'>hadrian: fix hadrian building with ghc-9.10.1
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/ad38e954bf088b43fa1cecfeaf474b6b9c11e2ed">ad38e954</a></strong>
<div>
<span> by Cheng Shao </span> <i> at 2024-05-13T22:21:43-04:00 </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;'>linters: fix lint-whitespace compilation with ghc-9.10.1
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/aef813106689d6866fdbd0965cd8e7dc0eb836f7">aef81310</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:00:24+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;'>Add Eq and Ord instance to `IfaceType`
We add an `Ord` instance so that we can store `IfaceType` in a
`Data.Map` container.
This is required to deduplicate `IfaceType` while writing `.hi` files to
disk. Deduplication has many beneficial consequences to both file size
and memory usage, as the deduplication enables implicit sharing of
values.
See issue #24540 for more motivation.
The `Ord` instance would be unnecessary if we used a `TrieMap` instead
of `Data.Map` for the deduplication process. While in theory this is
clerarly the better option, experiments on the agda code base showed
that a `TrieMap` implementation has worse run-time performance
characteristics.
To the change itself, we mostly derive `Eq` and `Ord`. This requires us
to change occurrences of `FastString` with `LexicalFastString`, since
`FastString` has no `Ord` instance.
We change the definition of `IfLclName` to a newtype of
`LexicalFastString`, to make such changes in the future easier.
Bump haddock submodule for IfLclName changes
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/531dfd3ec5ecca9c22c7263d839129b31846287b">531dfd3e</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:00:24+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;'>Move out LiteralMap to avoid cyclic module dependencies
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3447248eb14ac294d259f49e997203df53ebd78b">3447248e</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:00:24+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;'>Add deduplication table for `IfaceType`
The type `IfaceType` is a highly redundant, tree-like data structure.
While benchmarking, we realised that the high redundancy of `IfaceType`
causes high memory consumption in GHCi sessions when byte code is
embedded into the `.hi` file via `-fwrite-if-simplified-core` or
`-fbyte-code-and-object-code`.
Loading such `.hi` files from disk introduces many duplicates of
memory expensive values in `IfaceType`, such as `IfaceTyCon`,
`IfaceTyConApp`, `IA_Arg` and many more.
We improve the memory behaviour of GHCi by adding an additional
deduplication table for `IfaceType` to the serialisation of `ModIface`,
similar to how we deduplicate `Name`s and `FastString`s.
When reading the interface file back, the table allows us to automatically
share identical values of `IfaceType`.
To provide some numbers, we evaluated this patch on the agda code base.
We loaded the full library from the `.hi` files, which contained the
embedded core expressions (`-fwrite-if-simplified-core`).
Before this patch:
* Load time: 11.7 s, 2.5 GB maximum residency.
After this patch:
* Load time: 7.3 s, 1.7 GB maximum residency.
This deduplication has the beneficial side effect to additionally reduce
the size of the on-disk interface files tremendously.
For example, on agda, we reduce the size of `.hi` files (with
`-fwrite-if-simplified-core`):
* Before: 101 MB on disk
* Now: 24 MB on disk
This has even a beneficial side effect on the cabal store. We reduce the
size of the store on disk:
* Before: 341 MB on disk
* Now: 310 MB on disk
Note, none of the dependencies have been compiled with
`-fwrite-if-simplified-core`, but `IfaceType` occurs in multiple
locations in a `ModIface`.
We also add IfaceType deduplication table to .hie serialisation and
refactor .hie file serialisation to use the same infrastrucutre as
`putWithTables`.
Bump haddock submodule to accomodate for changes to the deduplication
table layout and binary interface.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7e99b3508197267b9d8271036345568eeec0222f">7e99b350</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:00:24+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;'>Add run-time configurability of `.hi` file compression
Introduce the flag `-fwrite-if-compression=<n>` which allows to
configure the compression level of writing .hi files.
The motivation is that some deduplication operations are too expensive
for the average use case. Hence, we introduce multiple compression
levels with variable impact on performance, but still reduce the
memory residency and `.hi` file size on disk considerably.
We introduce three compression levels:
* `1`: `Normal` mode. This is the least amount of compression.
It deduplicates only `Name` and `FastString`s, and is naturally the
fastest compression mode.
* `2`: `Safe` mode. It has a noticeable impact on .hi file size and is
marginally slower than `Normal` mode. In general, it should be safe to
always use `Safe` mode.
* `3`: `Full` deduplication mode. Deduplicate as much as we can,
resulting in minimal .hi files, but at the cost of additional
compilation time.
Reading .hi files doesn't need to know the initial compression level,
and can always deserialise a `ModIface`, as we write out a byte that
indicates the next value has been deduplicated.
This allows users to experiment with different compression levels for
packages, without recompilation of dependencies.
Note, the deduplication also has an additional side effect of reduced
memory consumption to implicit sharing of deduplicated elements.
See https://gitlab.haskell.org/ghc/ghc/-/issues/24540 for example where
that matters.
-------------------------
Metric Decrease:
MultiLayerModulesDefsGhciWithCore
T16875
T21839c
T24471
hard_hole_fits
libdir
-------------------------
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0c246d82ed9eb74d109c05cddb93d9dd40c23896">0c246d82</a></strong>
<div>
<span> by Matthew Pickering </span> <i> at 2024-05-14T13:00:24+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;'>Introduce regression tests for `.hi` file sizes
Add regression tests to track how `-fwrite-if-compression` levels affect
the size of `.hi` files.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c05ff9fe213acb58dfe92c7020b4fda5e58d24b8">c05ff9fe</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:01:32+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`
As a `ModIface` contains often 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 reduced 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/e4e4f7a7aa21bbbe8b86be94f6bb4b211e554955">e4e4f7a7</a></strong>
<div>
<span> by Fendor </span> <i> at 2024-05-14T13:31:57+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 serailised 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 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.
This leads to new primitives for `ModIface`, which help to construct
relative offsets.
Bump Haddock submodule, to account for interface file changes.
-------------------------
Metric Increase:
MultiComponentModules
MultiLayerModules
T10421
T12425
T13035
T13701
T13719
T14697
T18730
T9198
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 neglible impact on run-time performance.
</pre>
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