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<p class="MsoNormal">Should this be merged into 6.0?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">llvm-commits <llvm-commits-bounces@lists.llvm.org> on behalf of Dimitry Andric via llvm-commits <llvm-commits@lists.llvm.org><br>
<b>Reply-To: </b>Dimitry Andric <dimitry@andric.com><br>
<b>Date: </b>Thursday, January 11, 2018 at 12:04 AM<br>
<b>To: </b>"llvm-commits@lists.llvm.org" <llvm-commits@lists.llvm.org><br>
<b>Subject: </b>[lld] r322264 - Fix thread race between SectionPiece's OutputOff and Live members<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Author: dim<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Date: Thu Jan 11 00:03:22 2018<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">New Revision: 322264<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">URL: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D322264-26view-3Drev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=l5swfwKkexIb_mVxncjt1ygki08cGq_Xj6D46fD5OqM&e=">
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D322264-26view-3Drev&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=l5swfwKkexIb_mVxncjt1ygki08cGq_Xj6D46fD5OqM&e=</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Log:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Fix thread race between SectionPiece's OutputOff and Live members<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Summary:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">As reported in bug 35788, rL316280 reintroduces a race between two<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">members of SectionPiece, which share the same 64 bit memory location.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">To fix the race, check the hash before checking the Live member, as<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">suggested by Rafael.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Reviewers: ruiu, rafael<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Reviewed By: ruiu<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Subscribers: smeenai, emaste, llvm-commits<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Differential Revision: <a href="https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D41884&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=dy5VuBxeCmtDUygIahWUYtVcPQTAypaA-1W-lJsyTMc&e=">
https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D41884&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=dy5VuBxeCmtDUygIahWUYtVcPQTAypaA-1W-lJsyTMc&e=</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Modified:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> lld/trunk/ELF/SyntheticSections.cpp<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Modified: lld/trunk/ELF/SyntheticSections.cpp<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">URL: <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_lld_trunk_ELF_SyntheticSections.cpp-3Frev-3D322264-26r1-3D322263-26r2-3D322264-26view-3Ddiff&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=Y5724oLNQOEvmUSt4gRXiCeTBv9BgWDLqZc-WjB_LyQ&e=">
https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_lld_trunk_ELF_SyntheticSections.cpp-3Frev-3D322264-26r1-3D322263-26r2-3D322264-26view-3Ddiff&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=Y5724oLNQOEvmUSt4gRXiCeTBv9BgWDLqZc-WjB_LyQ&e=</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">==============================================================================<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">--- lld/trunk/ELF/SyntheticSections.cpp (original)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">+++ lld/trunk/ELF/SyntheticSections.cpp Thu Jan 11 00:03:22 2018<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">@@ -2451,10 +2451,8 @@ void MergeNoTailSection::finalizeContent<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> parallelForEachN(0, Concurrency, [&](size_t ThreadId) {<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> for (MergeInputSection *Sec : Sections) {<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I) {<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">- if (!Sec->Pieces[I].Live)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">- continue;<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> size_t ShardId = getShardId(Sec->Pieces[I].Hash);<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">- if ((ShardId & (Concurrency - 1)) == ThreadId)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">+ if ((ShardId & (Concurrency - 1)) == ThreadId && Sec->Pieces[I].Live)<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> Sec->Pieces[I].OutputOff = Shards[ShardId].add(Sec->getData(I));<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> }<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> }<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">_______________________________________________<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">llvm-commits mailing list<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Dcommits&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=YZq7G3sWEhLNixHYrxl6zXBuu0ZSTRGlLhLss21Ce2E&e=">https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_llvm-2Dcommits&d=DwIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=Xzeycr3aeaH2s-dbwn36tREoztaX3UBAqTs_Puspq3c&s=YZq7G3sWEhLNixHYrxl6zXBuu0ZSTRGlLhLss21Ce2E&e=</a><o:p></o:p></p>
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