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<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">Ah yes. This is a long-standing wart:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"><![if !supportLists]><span style="font-size:12.0pt;mso-fareast-language:EN-US"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:12.0pt;mso-fareast-language:EN-US">The CoreTidy pass predicts what will be CAFFY (see https://ghc.haskell.org/trac/ghc/wiki/Commentary/Rts/Storage/GC/CAFs). It predicts that info because the output of CoreTidy
is what goes into interface files.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"><![if !supportLists]><span style="font-size:12.0pt;mso-fareast-language:EN-US"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:12.0pt;mso-fareast-language:EN-US">The CorePrep pass messes the code a bit<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l2 level1 lfo2"><![if !supportLists]><span style="font-size:12.0pt;mso-fareast-language:EN-US"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:12.0pt;mso-fareast-language:EN-US">The CoreToStg pass coverts to STG, and at that point we know for sure what will be CAFFY and what will not<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">The assert trips when the predication in (1) doesn’t agree with reality in (3).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">It would be Much Much better if we took the info from (3) and used that to drive the Core-to-IfaceSyn conversion that creates the interface file content.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">The only reason not to do this is that it’d mean delaying Core-to-IfaceSyn until pass (3) had happened.. possibly bad for space. But maybe it’s a non-issue in practice.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">See
<a href="https://ghc.haskell.org/trac/ghc/ticket/9718">https://ghc.haskell.org/trac/ghc/ticket/9718</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;mso-fareast-language:EN-US">Windows interacts with this because with DLLs some pointers that would be static closures turn into thunks (I think).
See </span><span style="font-size:10.0pt;font-family:"Courier New"">StgSyn.isDllConApp</span><span style="font-size:12.0pt;font-family:"Times New Roman",serif">, and
</span><span style="font-size:10.0pt;font-family:"Courier New"">TidyPgm.hasCafRefs</span><span style="font-size:12.0pt;font-family:"Times New Roman",serif">
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-devs [mailto:ghc-devs-bounces@haskell.org]
<b>On Behalf Of </b>lonetiger@gmail.com<br>
<b>Sent:</b> 15 June 2016 00:26<br>
<b>To:</b> Ömer Sinan Ağacan <omeragacan@gmail.com><br>
<b>Cc:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> RE: CoreToStg Asserts<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Hi Ömer,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks for the pointers, should help me find out more.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It’s not a stock GHC as I’m working on getting Dynamic linking back on Windows.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This assert is triggered on the dyn version of the libs. So something’s bit rotted here.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Tamar<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US">From: </span></b><span lang="EN-US"><a href="mailto:omeragacan@gmail.com">Ömer Sinan Ağacan</a><br>
<b>Sent: </b>Tuesday, June 14, 2016 18:46<br>
<b>To: </b><a href="mailto:lonetiger@gmail.com">Phyx</a><br>
<b>Cc: </b><a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a><br>
<b>Subject: </b>Re: CoreToStg Asserts<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Hi Tamar,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Have a look at Note [Disgusting computation of CafRefs] in TidyPgm.hs. The<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">assertion triggered here is the one that checks `hasCafRefs` mentioned in that<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">note matches with actual CAF-ness.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Are you using stock GHC? Which version? Do you have a minimal program that<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">reproduces this?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">2016-06-13 7:01 GMT-04:00 Phyx <<a href="mailto:lonetiger@gmail.com">lonetiger@gmail.com</a>>:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Hi *,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> I'm hoping someone could help me understand what the asserts in CoreToStg on<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> line 240 and 216 are trying to tell me.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> I hit both of them while trying to compile libraries as dyn.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> WARNING: file compiler\stgSyn\CoreToStg.hs, line 250<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> $trModule2 False True<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> ghc-stage1.exe: panic! (the 'impossible' happened)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> (GHC version 8.1.20160612 for x86_64-unknown-mingw32):<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> ASSERT failed!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> file compiler\stgSyn\CoreToStg.hs line 216 $trModule2<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Please report this as a GHC bug: <a href="http://www.haskell.org/ghc/reportabug">
http://www.haskell.org/ghc/reportabug</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> WARNING: file compiler\simplCore\SimplCore.hs, line 633<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Simplifier bailing out after 4 iterations [6737, 736, 51, 9]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Size = {terms: 12,990, types: 9,998, coercions: 443}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> WARNING: file compiler\stgSyn\CoreToStg.hs, line 250<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> $fEqBigNat_$c/= False True<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> ghc-stage1.exe: panic! (the 'impossible' happened)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> (GHC version 8.1.20160612 for x86_64-unknown-mingw32):<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> ASSERT failed!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> file compiler\stgSyn\CoreToStg.hs line 240<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> [$fEqBigNat_$c/=, $fEqBigNat]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Please report this as a GHC bug: <a href="http://www.haskell.org/ghc/reportabug">
http://www.haskell.org/ghc/reportabug</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Kind Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> Tamar<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> _______________________________________________<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> ghc-devs mailing list<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> <a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">> <a href="http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs">
http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs</a><o:p></o:p></span></p>
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