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<h3>
Simon Peyton Jones pushed to branch wip/T18502
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/aee45d9ea8c6cf4ebad4d5c732748923c7865cbe">aee45d9e</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-07-27T07:06:56-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Improve NegativeLiterals (#18022, GHC Proposal #344)
Before this patch, NegativeLiterals used to parse x-1 as x (-1).
This may not be what the user expects, and now it is fixed:
x-1 is parsed as (-) x 1.
We achieve this by the following requirement:
* When lexing a negative literal,
it must not be preceded by a 'closing token'.
This also applies to unboxed literals, e.g. -1#.
See GHC Proposal #229 for the definition of a closing token.
A nice consequence of this change is that -XNegativeLiterals becomes a
subset of -XLexicalNegation. In other words, enabling both of those
extensions has the same effect as enabling -XLexicalNegation alone.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/667ab69e5edacb2ce2f42fb810cd54c8f856d30b">667ab69e</a></strong>
<div>
<span>by leiftw</span>
<i>at 2020-07-27T07:07:32-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">fix typo referring to non-existent `-ohidir` flag, should be `-hidir` I think</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6ff89c173f39813f74d7bbf95770c5e40039f155">6ff89c17</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-07-27T07:08:07-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Refactor the parser a little
* Create a dedicated production for type operators
* Create a dedicated type for the UNPACK pragma
* Remove an outdated part of Note [Parsing data constructors is hard]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/aa054d32a8ff69c334293a0d6c9d11b83a236a96">aa054d32</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-27T20:09:07-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Drop 32-bit Windows support
As noted in #18487, we have reached the end of this road.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6da73bbf97cca8bd64d70a26298e7f7ddad2ce52">6da73bbf</a></strong>
<div>
<span>by Michalis Pardalos</span>
<i>at 2020-07-27T20:09:44-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add minimal test for #12492
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/47680cb76b068508fd16d052e0a3bed12e38ea5f">47680cb7</a></strong>
<div>
<span>by Michalis Pardalos</span>
<i>at 2020-07-27T20:09:44-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Use allocate, not ALLOC_PRIM_P for unpackClosure#
ALLOC_PRIM_P fails for large closures, by directly using allocate
we can handle closures which are larger than the block size.
Fixes #12492
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3d345c9680ab3d766ef43dd8389ccc1eaeca066c">3d345c96</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-27T20:10:19-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Eta-expand the Simplifier monad
This patch eta-expands the Simplifier's monad, using the method
explained in GHC.Core.Unify Note [The one-shot state monad trick].
It's part of the exta-expansion programme in #18202.
It's a tiny patch, but is worth a 1-2% reduction in bytes-allocated
by the compiler. Here's the list, based on the compiler-performance
tests in perf/compiler:
Reduction in bytes allocated
T10858(normal) -0.7%
T12425(optasm) -1.3%
T13056(optasm) -1.8%
T14683(normal) -1.1%
T15164(normal) -1.3%
T15630(normal) -1.4%
T17516(normal) -2.3%
T18282(normal) -1.6%
T18304(normal) -0.8%
T1969(normal) -0.6%
T4801(normal) -0.8%
T5321FD(normal) -0.7%
T5321Fun(normal) -0.5%
T5642(normal) -0.9%
T6048(optasm) -1.1%
T9020(optasm) -2.7%
T9233(normal) -0.7%
T9675(optasm) -0.5%
T9961(normal) -2.9%
WWRec(normal) -1.2%
Metric Decrease:
T12425
T9020
T9961
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/57aca6bba1c000f8542ce94e8b724b0334ff96d4">57aca6bb</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-27T20:10:54-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">gitlab-ci: Ensure that Hadrian jobs don't download artifacts
Previously the Hadrian jobs had the default dependencies, meaning that
they would download artifacts from all jobs of earlier stages. This is
unneccessary.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0a815cea9fa11ce6ef22aec3525dd7a0df541daf">0a815cea</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-27T20:10:54-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">gitlab-ci: Bump bootstrap compiler to 8.8.4
Hopefully this will make the Windows jobs a bit more reliable.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0bd60059b0edfee9e8f66c6817257bbb946656cd">0bd60059</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-28T02:01:49-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">This patch addresses the exponential blow-up in the simplifier.
Specifically:
#13253 exponential inlining
#10421 ditto
#18140 strict constructors
#18282 another nested-function call case
This patch makes one really significant changes: change the way that
mkDupableCont handles StrictArg. The details are explained in
GHC.Core.Opt.Simplify Note [Duplicating StrictArg].
Specific changes
* In mkDupableCont, when making auxiliary bindings for the other arguments
of a call, add extra plumbing so that we don't forget the demand on them.
Otherwise we haev to wait for another round of strictness analysis. But
actually all the info is to hand. This change affects:
- Make the strictness list in ArgInfo be [Demand] instead of [Bool],
and rename it to ai_dmds.
- Add as_dmd to ValArg
- Simplify.makeTrivial takes a Demand
- mkDupableContWithDmds takes a [Demand]
There are a number of other small changes
1. For Ids that are used at most once in each branch of a case, make
the occurrence analyser record the total number of syntactic
occurrences. Previously we recorded just OneBranch or
MultipleBranches.
I thought this was going to be useful, but I ended up barely
using it; see Note [Note [Suppress exponential blowup] in
GHC.Core.Opt.Simplify.Utils
Actual changes:
* See the occ_n_br field of OneOcc.
* postInlineUnconditionally
2. I found a small perf buglet in SetLevels; see the new
function GHC.Core.Opt.SetLevels.hasFreeJoin
3. Remove the sc_cci field of StrictArg. I found I could get
its information from the sc_fun field instead. Less to get
wrong!
4. In ArgInfo, arrange that ai_dmds and ai_discs have a simpler
invariant: they line up with the value arguments beyond ai_args
This allowed a bit of nice refactoring; see isStrictArgInfo,
lazyArgcontext, strictArgContext
There is virtually no difference in nofib. (The runtime numbers
are bogus -- I tried a few manually.)
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
fft +0.0% -2.0% -48.3% -49.4% 0.0%
multiplier +0.0% -2.2% -50.3% -50.9% 0.0%
--------------------------------------------------------------------------------
Min -0.4% -2.2% -59.2% -60.4% 0.0%
Max +0.0% +0.1% +3.3% +4.9% 0.0%
Geometric Mean +0.0% -0.0% -33.2% -34.3% -0.0%
Test T18282 is an existing example of these deeply-nested strict calls.
We get a big decrease in compile time (-85%) because so much less
inlining takes place.
Metric Decrease:
T18282
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6ee07b494ddd0131d53ea2fd6a4bb29cd05f4dd8">6ee07b49</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-28T02:02:27-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Bignum: add support for negative shifts (fix #18499)
shiftR/shiftL support negative arguments despite Haskell 2010 report
saying otherwise. We explicitly test for negative values which is bad
(it gets in the way of constant folding, etc.). Anyway, for consistency
we fix Bits instancesof Integer/Natural.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f305bbfd0d7afee8fe7464252fbfc167205220ae">f305bbfd</a></strong>
<div>
<span>by Peter Trommler</span>
<i>at 2020-07-28T02:03:02-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">config: Fix Haskell platform constructor w/ params
Fixes #18505
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/49d8597c9da32a5b674987cdc6ee227bcb627bb2">49d8597c</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-28T10:14:32+01:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add two bangs to improve perf of flattening
This tiny patch improves the compile time of flatten-heavy
programs by 1-2%, by adding two bangs.
Addresses (somewhat) #18502
This reduces allocation by
T9872b -1.1%
T9872d -3.3%
T5321Fun -0.2%
T5631 -0.2%
T5837 +0.1%
T6048 +0.1%
Metric Decrease:
T9872b
T9872d
</pre>
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.gitlab-ci.yml
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