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      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Infinite loop in -callsite-splitting"
   href="https://bugs.llvm.org/show_bug.cgi?id=36105">36105</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Infinite loop in -callsite-splitting
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </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>new bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>mikael.holmen@ericsson.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=19755" name="attach_19755" title="reproducer">attachment 19755</a> <a href="attachment.cgi?id=19755&action=edit" title="reproducer">[details]</a></span>
reproducer

Running

 opt -S -o - foo.ll -callsite-splitting

we get stuck and loop forever in function recordConditions in
CallSitesplitting.cpp:

/// Record ICmp conditions relevant to any argument in CS following Pred's
/// single successors. If there are conflicting conditions along a path, like
/// x == 1 and x == 0, the first condition will be used.
static void recordConditions(CallSite CS, BasicBlock *Pred,
                             ConditionsTy &Conditions) {
  recordCondition(CS, Pred, CS.getInstruction()->getParent(), Conditions);
  BasicBlock *From = Pred;
  BasicBlock *To = Pred;
  SmallPtrSet<BasicBlock *, 4> Visited = {From};
  while (!Visited.count(From->getSinglePredecessor()) &&
         (From = From->getSinglePredecessor())) {
    recordCondition(CS, From, To, Conditions);
    To = From;
  }
}

It looks suspicious to me that Visited isn't updated in the loop.</pre>
        </div>
      </p>


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