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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 - AArch64 missed optimization involving "or(frameindex, n)""
   href="https://bugs.llvm.org/show_bug.cgi?id=46151">46151</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>AArch64 missed optimization involving "or(frameindex, n)"
          </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>Windows NT
          </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>efriedma@quicinc.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>arnaud.degrandmaison@arm.com, llvm-bugs@lists.llvm.org, smithp352@googlemail.com, Ties.Stuij@arm.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Consider the following testcase:

int test(long n, void test2(int*)) {
  int a[4] __attribute((aligned(16)));
  test2(a);
  return a[n & 3];
}

(Similar patterns can come up with variable-index extractelement.)

Currently, we generate something like the following:

  mov x20, sp
  and x8, x19, #0x3
  bfi x20, x8, #2, #2
  ldr w0, [x20]

If the "aligned" attribute is removed, we instead generate:

  mov x20, sp
  and x8, x19, #0x3
  ldr w0, [x20, x8, lsl #2]</pre>
        </div>
      </p>


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