<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html lang="en">
<head>
<meta content="text/html; charset=US-ASCII" http-equiv="Content-Type">
<title>
GitLab
</title>
<style>img {
max-width: 100%; height: auto;
}
</style>
</head>
<body>
<div class="content">
<h3>
Sebastian Graf pushed to branch wip/T18078
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/f9823d86e55a19ee5633fd83585f51e988237be6">f9823d86</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-06-09T11:07:26+02:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Implement cast worker/wrapper properly
The cast worker/wrapper transformation transforms
x = e |> co
into
y = e
x = y |> co
This is done by the simplifier, but we were being
careless about transferring IdInfo from x to y,
and about what to do if x is a NOINLNE function.
This resulted in a series of bugs:
#17673, #18093, #18078.
This patch fixes all that:
* Main change is in GHC.Core.Opt.Simplify, and
the new prepareBinding function, which does this
cast worker/wrapper transform.
See Note [Cast worker/wrappers].
* There is quite a bit of refactoring around
prepareRhs, makeTrivial etc. It's nicer now.
* Some wrappers from strictness and cast w/w, notably those for
a function with a NOINLINE, should inline very late. There
wasn't really a mechanism for that, which was an existing bug
really; so I invented a new finalPhase = Phase (-1). It's used
for all simplifier runs after the user-visible phase 2,1,0 have
run. (No new runs of the simplifier are introduced thereby.)
See new Note [Compiler phases] in GHC.Types.Basic;
the main changes are in GHC.Core.Opt.Driver
* Doing this made me trip over two places where the AnonArgFlag on a
FunTy was being lost so we could end up with (Num a -> ty)
rather than (Num a => ty)
- In coercionLKind/coercionRKind
- In contHoleType in the Simplifier
I fixed the former by defining mkFunctionType and using it in
coercionLKind/RKind.
I could have done the same for the latter, but the information
is almost to hand. So I fixed the latter by
- adding sc_hole_ty to ApplyToVal (like ApplyToTy),
- adding as_hole_ty to ValArg (like TyArg)
- adding sc_fun_ty to StrictArg
Turned out I could then remove ai_type from ArgInfo. This is
just moving the deck chairs around, but it worked out nicely.
See the new Note [AnonArgFlag] in GHC.Types.Var
* When looking at the 'arity decrease' thing (#18093) I discovered
that stable unfoldings had a much lower arity than the actual
optimised function. That's what led to the arity-decrease
message. Simple solution: eta-expand.
It's described in Note [Eta-expand stable unfoldings]
in GHC.Core.Opt.Simplify
* I also discovered that unsafeCoerce wasn't being inlined if
the context was boring. So (\x. f (unsafeCoerce x)) would
create a thunk -- yikes! I fixed that by making inlineBoringOK
a bit cleverer: see Note [Inline unsafeCoerce] in GHC.Core.Unfold.
I also found that unsafeCoerceName was unused, so I removed it.
I made a test case for #18078, and a very similar one for #17673.
The net effect of all this on nofib is very modest, but positive:
--------------------------------------------------------------------------------
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
anna -0.4% -0.1% -3.1% -3.1% 0.0%
fannkuch-redux -0.4% -0.3% -0.1% -0.1% 0.0%
maillist -0.4% -0.1% -7.8% -1.0% -14.3%
primetest -0.4% -15.6% -7.1% -6.6% 0.0%
--------------------------------------------------------------------------------
Min -0.9% -15.6% -13.3% -14.2% -14.3%
Max -0.3% 0.0% +12.1% +12.4% 0.0%
Geometric Mean -0.4% -0.2% -2.3% -2.2% -0.1%
Metric Decrease:
T5631
T13701
T14697
T15164
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
<ul>
<li class="file-stats">
<a href="#0887cf39c5cdf9cf8d6758f410d7dab3023c0d77">
compiler/GHC/Builtin/Names.hs
</a>
</li>
<li class="file-stats">
<a href="#783e5dae6e86931f06700fc088fb7d48c8a07386">
compiler/GHC/Core/Coercion.hs
</a>
</li>
<li class="file-stats">
<a href="#446b4afbe6836b950115a619acea24ddde19dc90">
compiler/GHC/Core/Opt/CSE.hs
</a>
</li>
<li class="file-stats">
<a href="#c1bf6b849619bc8d7ef37a97d993dbfaa9966f7b">
compiler/GHC/Core/Opt/CprAnal.hs
</a>
</li>
<li class="file-stats">
<a href="#f2f5de8b9f31451d693079c2a2d27fb47b18a3f4">
compiler/GHC/Core/Opt/Driver.hs
</a>
</li>
<li class="file-stats">
<a href="#f168a93cde5e2aec2441d6331dfe500172df4af3">
compiler/GHC/Core/Opt/Simplify.hs
</a>
</li>
<li class="file-stats">
<a href="#48fbb5cdea308650de5756521feb28ec68819b9b">
compiler/GHC/Core/Opt/Simplify/Utils.hs
</a>
</li>
<li class="file-stats">
<a href="#b6a5ba32bafb8fbda933538b3007e755fef6f101">
compiler/GHC/Core/Opt/SpecConstr.hs
</a>
</li>
<li class="file-stats">
<a href="#5b215b0e109123e4bef5434854f18e2f61c45b88">
compiler/GHC/Core/Opt/WorkWrap.hs
</a>
</li>
<li class="file-stats">
<a href="#11ffe98a94d798427bc600e4fcfe899407536346">
compiler/GHC/Core/SimpleOpt.hs
</a>
</li>
<li class="file-stats">
<a href="#84c9d3ba34173297e7d7747e02caa2e004b164fc">
compiler/GHC/Core/Type.hs
</a>
</li>
<li class="file-stats">
<a href="#2811a7297b8aa206197ac1f5dabd0818e3c7ec5a">
compiler/GHC/Core/Unfold.hs
</a>
</li>
<li class="file-stats">
<a href="#1a7aba0daeafab195716dd25432479804a55ab60">
compiler/GHC/Core/Utils.hs
</a>
</li>
<li class="file-stats">
<a href="#a5d27de4e3111a69f69902c65ecf7b3379f7c49a">
compiler/GHC/CoreToStg/Prep.hs
</a>
</li>
<li class="file-stats">
<a href="#166e3514d27c63ef7e86af29830d9e8b2a31c8b1">
compiler/GHC/Types/Basic.hs
</a>
</li>
<li class="file-stats">
<a href="#261c0c5029eb34eb7436b087d77314f377ff8223">
compiler/GHC/Types/Id/Make.hs
</a>
</li>
<li class="file-stats">
<a href="#5dac619989e8509003cf7b463c100f5cc56072a3">
compiler/GHC/Types/Var.hs
</a>
</li>
<li class="file-stats">
<a href="#f35faa85de2e0a75cdaa452eb7336a09c677d450">
compiler/GHC/Utils/Binary.hs
</a>
</li>
<li class="file-stats">
<a href="#98b46afb652ad9b66a276d3c312d1262c3838642">
libraries/base/Unsafe/Coerce.hs
</a>
</li>
<li class="file-stats">
<a href="#f7296c640c970ad9c7ff46e3e4854d4ab2dd7c14">
testsuite/tests/codeGen/should_compile/debug.stdout
</a>
</li>
<li class="file-stats">
<a href="#71247aaad504d89a31c398d6edd6cfc090975b86">
testsuite/tests/deSugar/should_compile/T2431.stderr
</a>
</li>
<li class="file-stats">
<a href="#b788976ba3555853d385fd1c6246444c972d749f">
testsuite/tests/perf/compiler/T16473.stdout
</a>
</li>
<li class="file-stats">
<a href="#6e2ce964ea02e92c2202946150700a3219beed86">
testsuite/tests/simplCore/should_compile/T13143.stderr
</a>
</li>
<li class="file-stats">
<a href="#bed56c1799aaab17a90f7de64953a3c8b0b8de48">
<span class="new-file">
+
testsuite/tests/simplCore/should_compile/T17673.hs
</span>
</a>
</li>
<li class="file-stats">
<a href="#b60bc5262db8520abdfa01f255cd29eec5891d15">
<span class="new-file">
+
testsuite/tests/simplCore/should_compile/T17673.stderr
</span>
</a>
</li>
<li class="file-stats">
<a href="#05c47cd4b4d1fb1924b29f5b95b19813a5ce9fcd">
<span class="new-file">
+
testsuite/tests/simplCore/should_compile/T18078.hs
</span>
</a>
</li>
<li class="file-stats">
<a href="#d714e0dbbb2f419378e3fdd77e8efff312ad2e41">
<span class="new-file">
+
testsuite/tests/simplCore/should_compile/T18078.stderr
</span>
</a>
</li>
<li class="file-stats">
<a href="#ae44213f400f8badeaf992dd66c7c6bfd26ffd60">
testsuite/tests/simplCore/should_compile/T3772.stdout
</a>
</li>
<li class="file-stats">
<a href="#0e264f20bcb9f21ef8f19196ea35fb751107dd1f">
testsuite/tests/simplCore/should_compile/T7360.stderr
</a>
</li>
<li class="file-stats">
<a href="#e9ed289bdfe6bcb0204e76be84b2f377004a5d3d">
testsuite/tests/simplCore/should_compile/T7865.stdout
</a>
</li>
</ul>
<h5>The diff was not included because it is too large.</h5>
</div>
<div class="footer" style="margin-top: 10px;">
<p style="font-size: small; color: #777;">
—
<br>
<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f9823d86e55a19ee5633fd83585f51e988237be6">View it on GitLab</a>.
<br>
You're receiving this email because of your account on gitlab.haskell.org.
If you'd like to receive fewer emails, you can
adjust your notification settings.
<script type="application/ld+json">{"@context":"http://schema.org","@type":"EmailMessage","action":{"@type":"ViewAction","name":"View Commit","url":"https://gitlab.haskell.org/ghc/ghc/-/commit/f9823d86e55a19ee5633fd83585f51e988237be6"}}</script>
</p>
</div>
</body>
</html>