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    <head>
      <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 - [AArch64] failed to form 'ubfiz'"
   href="https://bugs.llvm.org/show_bug.cgi?id=43191">43191</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[AArch64] failed to form 'ubfiz'
          </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>enhancement
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>Backend: AArch64
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>spatel+llvm@rotateright.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>arnaud.degrandmaison@arm.com, llvm-bugs@lists.llvm.org, peter.smith@linaro.org, Ties.Stuij@arm.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>As discussed in:
<a href="https://reviews.llvm.org/D67021">https://reviews.llvm.org/D67021</a>
...there seems to be something missing in the transforms/recognition between
TLI.isDesirableToCommuteWithShift() and
AArch64DAGToDAGISel::tryBitfieldInsertInZeroOp() with this example:

define i32 @ubfiz(i8 %x) {
  %conv = zext i8 %x to i32
  %r = shl nuw nsw i32 %conv, 3
  ret i32 %r
}

$ llc -o - ubfiz.ll
  and   w8, w0, #0xff
  lsl   w0, w8, #3

But this could be:
  ubfiz w0, w0, #3, #8</pre>
        </div>
      </p>


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