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      <base href="https://bugs.llvm.org/">
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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 - Add a unit test for frame index expansion"
   href="https://bugs.llvm.org/show_bug.cgi?id=39554">39554</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Add a unit test for frame index expansion
          </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>Backend: AVR
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>me@dylanmckay.io
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>In avr-rust <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - casting a string constant to void crashes llvm-gcc"
   href="show_bug.cgi?id=112">bug #112</a>, we encountered a backend bug caused by invalid expansion
of a FRMIDX instruction into a MOVWRdRr instruction. The backend would leave an
extraneous operand from the original FRMIDX that was not consistent with the
definition of MOVWRdRr.

This would trigger an assertion:

    Assertion failed: ((isImpReg || Op.isRegMask() || MCID->isVariadic() ||
                        OpNo < MCID->getNumOperands() || isMetaDataOp) &&
                        "Trying to add an operand to a machine instr that is
already done!"),
    function addOperand, file llvm/lib/CodeGen/MachineInstr.cpp


More informatiob about that bug can be found at:
<a href="https://github.com/avr-rust/rust/issues/112">https://github.com/avr-rust/rust/issues/112</a>

We should write unit tests that cover the expansion of FRMIDX nodes into
MOVWRdRr instructions.</pre>
        </div>
      </p>


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