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<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Thanks for reverting it Jordan! I’ll take a look.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">--Max<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Jordan Rupprecht <rupprecht@google.com>
<br>
<b>Sent:</b> Wednesday, January 23, 2019 8:15 AM<br>
<b>To:</b> Maxim Kazantsev <max.kazantsev@azul.com><br>
<b>Cc:</b> llvm-commits@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm] r351520 - Re-enable terminator folding in LoopSimplifyCFG: underlying bugs fixed<o:p></o:p></span></p>
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<p class="MsoNormal">Here's the creduce + stack trace w/ a debug build:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">$ cat /tmp/repro.c</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">int a, b, *c, d, e;</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">void f() {</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> int g;</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> for (;;) {</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> for (; e; e = b) {</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> c = g;</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> for (; c; c = d)</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> if (a) break;</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> if (c) break;</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> }</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> }</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">$ clang -O1 -fexperimental-new-pass-manager -mllvm -enable-loop-simplifycfg-term-folding -c /tmp/repro.c</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">clang-9: ~/src/llvm-project/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp:63: void llvm::DeleteDeadBlocks(SmallVectorImpl<llvm::BasicBlock *> &, llvm::DomTreeUpdater *): Assertion</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">`Dead.count(Pred) && "All predecessors must be dead!"' failed.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">...</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> #9 0x00007f448da1723b llvm::DeleteDeadBlocks(llvm::SmallVectorImpl<llvm::BasicBlock*>&, llvm::DomTreeUpdater*) ~/src/llvm-project/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp:62:</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">5</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">#10 0x00007f448e5c67ab (anonymous namespace)::ConstantTerminatorFoldingImpl::deleteDeadLoopBlocks() ~/src/llvm-project/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp:415:5<o:p></o:p></span></p>
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<p class="MsoNormal">On Tue, Jan 22, 2019 at 9:43 AM Jordan Rupprecht <<a href="mailto:rupprecht@google.com">rupprecht@google.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">It looks like this is still causing crashes, so I've temporarily reverted this as
<a href="https://reviews.llvm.org/rL351845" target="_blank">https://reviews.llvm.org/rL351845</a>. I hope to have a repro later today.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Jan 17, 2019 at 9:01 PM Max Kazantsev via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Author: mkazantsev<br>
Date: Thu Jan 17 20:57:32 2019<br>
New Revision: 351520<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=351520&view=rev" target="_blank">
http://llvm.org/viewvc/llvm-project?rev=351520&view=rev</a><br>
Log:<br>
Re-enable terminator folding in LoopSimplifyCFG: underlying bugs fixed<br>
<br>
Modified:<br>
llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp<br>
<br>
Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=351520&r1=351519&r2=351520&view=diff" target="_blank">
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=351520&r1=351519&r2=351520&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)<br>
+++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Thu Jan 17 20:57:32 2019<br>
@@ -42,7 +42,7 @@ using namespace llvm;<br>
#define DEBUG_TYPE "loop-simplifycfg"<br>
<br>
static cl::opt<bool> EnableTermFolding("enable-loop-simplifycfg-term-folding",<br>
- cl::init(false));<br>
+ cl::init(true));<br>
<br>
STATISTIC(NumTerminatorsFolded,<br>
"Number of terminators folded to unconditional branches");<br>
<br>
<br>
_______________________________________________<br>
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<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits</a><o:p></o:p></p>
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