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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Simon Peyton Jones pushed to branch wip/T22404 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/a53193589ac5bd9973711733a7ccd66080dca794">a5319358</a></strong>
<div>
<span> by David Knothe </span> <i> at 2023-07-28T13:13:10-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: "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;'>Update Match Datatype
EquationInfo currently contains a list of the equation's patterns together with a CoreExpr that is to be evaluated after a successful match on this equation.
All the match-functions only operate on the first pattern of an equation - after successfully matching it, match is called recursively on the tail of the pattern list.
We can express this more clearly and make the code a little more elegant by updating the datatype of EquationInfo as follows:
data EquationInfo
= EqnMatch { eqn_pat = Pat GhcTc, eqn_rest = EquationInfo }
| EqnDone { eqn_rhs = MatchResult CoreExpr }
An EquationInfo now explicitly exposes its first pattern which most functions operate on, and exposes the equation that remains after processing the first pattern. An EqnDone signifies an empty equation where the CoreExpr can now be evaluated.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/86ad1af987747645b600bf9606509f27e4f3e45c">86ad1af9</a></strong>
<div>
<span> by David Binder </span> <i> at 2023-07-28T13:13:53-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: "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 documentation for Data.Fixed
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f8fa1d08d7cbfef508bab355bda80f495e928f98">f8fa1d08</a></strong>
<div>
<span> by Ben Gamari </span> <i> at 2023-07-28T13:14:31-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: "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-prim: Use C11 atomics
Previously `ghc-prim`'s atomic wrappers used the legacy `__sync_*`
family of C builtins. Here we refactor these to rather use the
appropriate C11 atomic equivalents, allowing us to be more explicit
about the expected ordering semantics.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/af04ebee389800f4350d22b7bb0e919604baf2eb">af04ebee</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-07-28T22:54:13+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: "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 the occurrence analyser smarter about join points
This MR addresses #22404. There is a big Note
Note [Occurrence analysis for join points]
that explains it all. Significant changes
* New field occ_join_points in OccEnv
* The NonRec case of occAnalBind splits into two cases:
one for existing join points (which does the special magic for
Note [Occurrence analysis for join points], and one for other
bindings.
* mkOneOcc adds in info from occ_join_points.
* All "bring into scope" activity is centralised in the
new function `addInScope`.
* I made a local data type LocalOcc for use inside the occurrence analyser
It is like OccInfo, but lacks IAmDead and IAmALoopBreaker, which in turn
makes computationns over it simpler and more efficient.
* I found quite a bit of allocation in GHC.Core.Rules.getRules
so I optimised it a bit.
More minor changes
* I found I was using (Maybe Arity) a lot, so I defined a new data
type JoinPointHood and used it everwhere. This touches a lot of
non-occ-anal files, but it makes everything more perspicuous.
* Renamed data constructor WithUsageDetails to WUD, and
WithTailUsageDetails to WTUD
This also fixes #21128, on the way.
--------- Compiler perf -----------
I spent quite a time on performance tuning, so even though it
does more than before, the occurrence analyser runs slightly faster
on average. Here are the compile-time allocation changes over 0.5%
CoOpt_Read(normal) ghc/alloc 766,025,520 754,561,992 -1.5%
CoOpt_Singletons(normal) ghc/alloc 759,436,840 762,925,512 +0.5%
LargeRecord(normal) ghc/alloc 1,814,482,440 1,799,530,456 -0.8%
PmSeriesT(normal) ghc/alloc 68,159,272 67,519,720 -0.9%
T10858(normal) ghc/alloc 120,805,224 118,746,968 -1.7%
T11374(normal) ghc/alloc 164,901,104 164,070,624 -0.5%
T11545(normal) ghc/alloc 79,851,808 78,964,704 -1.1%
T12150(optasm) ghc/alloc 73,903,664 71,237,544 -3.6% GOOD
T12227(normal) ghc/alloc 333,663,200 331,625,864 -0.6%
T12234(optasm) ghc/alloc 52,583,224 52,340,344 -0.5%
T12425(optasm) ghc/alloc 81,943,216 81,566,720 -0.5%
T13056(optasm) ghc/alloc 294,517,928 289,642,512 -1.7%
T13253-spj(normal) ghc/alloc 118,271,264 59,859,040 -49.4% GOOD
T15164(normal) ghc/alloc 1,102,630,352 1,091,841,296 -1.0%
T15304(normal) ghc/alloc 1,196,084,000 1,166,733,000 -2.5%
T15630(normal) ghc/alloc 148,729,632 147,261,064 -1.0%
T15703(normal) ghc/alloc 379,366,664 377,600,008 -0.5%
T16875(normal) ghc/alloc 32,907,120 32,670,976 -0.7%
T17516(normal) ghc/alloc 1,658,001,888 1,627,863,848 -1.8%
T17836(normal) ghc/alloc 395,329,400 393,080,248 -0.6%
T18140(normal) ghc/alloc 71,968,824 73,243,040 +1.8%
T18223(normal) ghc/alloc 456,852,568 453,059,088 -0.8%
T18282(normal) ghc/alloc 129,105,576 131,397,064 +1.8%
T18304(normal) ghc/alloc 71,311,712 70,722,720 -0.8%
T18698a(normal) ghc/alloc 208,795,112 210,102,904 +0.6%
T18698b(normal) ghc/alloc 230,320,736 232,697,976 +1.0% BAD
T19695(normal) ghc/alloc 1,483,648,128 1,504,702,976 +1.4%
T20049(normal) ghc/alloc 85,612,024 85,114,376 -0.6%
T21839c(normal) ghc/alloc 415,080,992 410,906,216 -1.0% GOOD
T4801(normal) ghc/alloc 247,590,920 250,726,272 +1.3%
T6048(optasm) ghc/alloc 95,699,416 95,080,680 -0.6%
T783(normal) ghc/alloc 335,323,384 332,988,120 -0.7%
T9233(normal) ghc/alloc 709,641,224 685,947,008 -3.3% GOOD
T9630(normal) ghc/alloc 965,635,712 948,356,120 -1.8%
T9675(optasm) ghc/alloc 444,604,152 428,987,216 -3.5% GOOD
T9961(normal) ghc/alloc 303,064,592 308,798,800 +1.9% BAD
WWRec(normal) ghc/alloc 503,728,832 498,102,272 -1.1%
geo. mean -1.0%
minimum -49.4%
maximum +1.9%
In fact these figures seem to vary between platforms; generally worse
on i386 for some reason. But the geom mean stay solidly negative, which
is good. The "increase/decrease" list below covers all platforms.
The big win on T13253-spj comes because it has a big nest of join
points, each occurring twice in the next one. The new occ-anal takes
only one iteration of the simplifier to do the inlining; the old one
took four. Moreover, we get much smaller code with the new one:
New: Result size of Tidy Core
= {terms: 429, types: 84, coercions: 0, joins: 14/14}
Old: Result size of Tidy Core
= {terms: 2,437, types: 304, coercions: 0, joins: 10/10}
--------- Runtime perf -----------
No significant changes in nofib results, except a 1% reduction in
compiler allocation.
Metric Decrease:
CoOpt_Read
T13253-spj
T9233
T9630
T9675
T12150
T21839c
LargeRecord
MultiComponentModulesRecomp
Metric Increase:
T18140
T9961
T18282
T18698a
T18698b
T19695
</pre>
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compiler/GHC/Core/Lint.hs
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compiler/GHC/Core/Opt/CSE.hs
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compiler/GHC/Core/Opt/DmdAnal.hs
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compiler/GHC/Core/Opt/Exitify.hs
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compiler/GHC/Core/Opt/FloatIn.hs
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compiler/GHC/Core/Opt/FloatOut.hs
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compiler/GHC/Stg/Lint.hs
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