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    <head>
      <base href="https://llvm.org/bugs/" />
    </head>
    <body><span class="vcard"><a class="email" href="mailto:sanjoy@playingwithpointers.com" title="Sanjoy Das <sanjoy@playingwithpointers.com>"> <span class="fn">Sanjoy Das</span></a>
</span> changed
              <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED DUPLICATE - Compiler crash in "Induction Variable Simplification" for "-fno-exceptions""
   href="https://llvm.org/bugs/show_bug.cgi?id=27945">bug 27945</a>
        <br>
             <table border="1" cellspacing="0" cellpadding="8">
          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
          </tr>

         <tr>
           <td style="text-align:right;">Status</td>
           <td>NEW
           </td>
           <td>RESOLVED
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">CC</td>
           <td>
                
           </td>
           <td>michael.v.zolotukhin@gmail.com
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">Resolution</td>
           <td>---
           </td>
           <td>DUPLICATE
           </td>
         </tr></table>
      <p>
        <div>
            <b><a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED DUPLICATE - Compiler crash in "Induction Variable Simplification" for "-fno-exceptions""
   href="https://llvm.org/bugs/show_bug.cgi?id=27945#c2">Comment # 2</a>
              on <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED DUPLICATE - Compiler crash in "Induction Variable Simplification" for "-fno-exceptions""
   href="https://llvm.org/bugs/show_bug.cgi?id=27945">bug 27945</a>
              from <span class="vcard"><a class="email" href="mailto:sanjoy@playingwithpointers.com" title="Sanjoy Das <sanjoy@playingwithpointers.com>"> <span class="fn">Sanjoy Das</span></a>
</span></b>
        <pre>Running with this patch 

diff --git a/lib/Analysis/LoopPass.cpp b/lib/Analysis/LoopPass.cpp
index 3181e4f..0ea2bf4 100644
--- a/lib/Analysis/LoopPass.cpp
+++ b/lib/Analysis/LoopPass.cpp
@@ -14,6 +14,7 @@

//===----------------------------------------------------------------------===//

 #include "llvm/Analysis/LoopPass.h"
+#include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/OptBisect.h"
@@ -197,6 +198,15 @@ bool LPPassManager::runOnFunction(Function &F) {
         TimeRegion PassTimer(getPassTimer(P));

         Changed |= P->runOnLoop(CurrentLoop, *this);
+
+        DominatorTree DT;
+        DT.recalculate(F);
+        for (auto *L : make_range(LI->begin(), LI->end())) {
+          if (!L->isRecursivelyLCSSAForm(DT)) {
+            dbgs() << "Broke LCSSA after running " << P->getPassName() << "n";
+            assert(false);
+          }
+        }
       }
       LoopWasDeleted = CurrentLoop->isInvalid();

Crashes as:

Broke LCSSA after running Unroll loops
Assertion failed: (false), function runOnFunction, file
../../lib/Analysis/LoopPass.cpp, line 207.


So it is most likely a duplicate of PR26682.

*** This bug has been marked as a duplicate of <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - crash on x86_64-linux-gnu at -O2 and above in both 32-bit and 64-bit modes (Assertion `L->isRecursivelyLCSSAForm(*DT) && "Indvars did not preserve LCSSA!"' failed)"
   href="show_bug.cgi?id=26682">bug 26682</a> ***</pre>
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