<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 --- - [ppc] missed vectorization of simple loop"
   href="https://llvm.org/bugs/show_bug.cgi?id=27252">27252</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[ppc] missed vectorization of simple loop
          </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>normal
          </td>
        </tr>

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

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

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

        <tr>
          <th>Reporter</th>
          <td>carrot@google.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Compile the following code with command line

~/llvm/obj3/bin/clang --target=powerpc64le-grtev4-linux-gnu -mvsx -mcpu=power8
-O2 -c t12.c -o t12.o

int foo(unsigned int* buf, unsigned int end, unsigned int endmask){
  unsigned int* p;
  int sum = 0;

  for (p = buf; p < buf + end; ++p) { 
    sum += __builtin_popcount(*p);
  }

  return sum + __builtin_popcount(*p & endmask);
}


The simple loop is unrolled but not vectorized. If I change the last line to

   return sum;

Then the loop can be vectorized.</pre>
        </div>
      </p>
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