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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 - In SchedMachineModel, specifying SchedWrite in ReadAdvance doesn't work."
   href="https://bugs.llvm.org/show_bug.cgi?id=37324">37324</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>In SchedMachineModel, specifying SchedWrite in ReadAdvance doesn't work.
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>6.0
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>Target Description Classes
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>swpenim@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>I want to write a ReadAdvance that will only be applied to a SchedWrite. After
specifying it in ReadAdvance, it doesn't work.

For example, 
We have a 4-cycle latency from a LDRi12 to MLA in cortexR52 on Arm backend with
function foo.

int foo(int *p) {
  return p[0] * p[1] + p[2];
}

If I change ARMScheduleR52.td as follows:

-def : ReadAdvance<R52Read_ISS, 0>;
+def : ReadAdvance<R52Read_ISS, 1, [R52WriteLd]>;

and move definition of R52WriteLd earlier, we can find the latency is still the
same.

But if I remove R52WriteLd in ReadAdvance, the latency is reduced to 3.</pre>
        </div>
      </p>


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