<html>
    <head>
      <base href="https://llvm.org/bugs/" />
    </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 --- - NewGVN fails to verify memory congruency"
   href="https://llvm.org/bugs/show_bug.cgi?id=31573">31573</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>NewGVN fails to verify memory congruency
          </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>All
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>Scalar Optimizations
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>davide@freebsd.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dberlin@dberlin.org, llvm-bugs@lists.llvm.org, paulsson@linux.vnet.ibm.com
          </td>
        </tr>

        <tr>
          <th>Blocks</th>
          <td>30995
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Reduced from Jonas Paulsson's report.

define void @patatino(i8* %blah) {
entry:
  br label %while.cond

while.cond:
  %meh = phi i8* [ %blah, %entry ], [ null, %while.body ]
  switch i32 undef, label %while.body [
    i32 666, label %while.end
  ]

while.body:
  br label %while.cond

while.end:
  store i8 0, i8* %meh, align 1
  store i8 0, i8* %blah, align 1
  ret void
}

$ opt -newgvn patatuccio.ll -o /dev/null
opt: ../lib/Transforms/Scalar/NewGVN.cpp:1477: void
NewGVN::verifyMemoryCongruency(): Assertion
`ValueToClass.lookup(FirstMUD->getMemoryInst()) ==
ValueToClass.lookup(SecondMUD->getMemoryInst()) && "The instructions for these
memory operations should have been in " "the same congruence class"' failed.
[...]</pre>
        </div>
      </p>
      <hr>
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      <ul>
          <li>You are on the CC list for the bug.</li>
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