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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [SimpleLoopUnswitch] Assertion `OldContainingL->hasDedicatedExits() && "Unexpected predecessor of hoisted loop preheader!"' failed."
   href="https://bugs.llvm.org/show_bug.cgi?id=38283">38283</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[SimpleLoopUnswitch]  Assertion `OldContainingL->hasDedicatedExits() && "Unexpected predecessor of hoisted loop preheader!"' failed.
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Loop Optimizer
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>paulsson@linux.vnet.ibm.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=20593" name="attach_20593" title="reduced testcase">attachment 20593</a> <a href="attachment.cgi?id=20593&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase

Getting dozens of test failures with -enable-simple-loop-unswitch currently.
Attached is a reduced test case for opt:

opt -mtriple=s390x-linux-gnu -O3 -mcpu=z13 -enable-simple-loop-unswitch
./tc_simpleloopunsw.ll

opt:
/home/ijonpan/llvm/llvm-dev/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp:308:
void hoistLoopToNewParent(llvm::Loop&, llvm::BasicBlock&, llvm::DominatorTree&,
llvm::LoopInfo&): Assertion `OldContainingL->hasDedicatedExit\
s() && "Unexpected predecessor of hoisted loop preheader!"' failed.
Stack dump:
0.      Program arguments: /home/ijonpan/llvm/build/llvm-dev/bin/opt
-mtriple=s390x-linux-gnu -O3 -mcpu=z13 -enable-simple-loop-unswitch
./tc_simpleloopunsw.ll
1.      Running pass 'CallGraph Pass Manager' on module
'./tc_simpleloopunsw.ll'.
2.      Running pass 'Loop Pass Manager' on function '@func_9'
3.      Running pass 'Simple unswitch loops' on basic block '%bb9'
...</pre>
        </div>
      </p>


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