<html>
    <head>
      <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 - Failure to optimize simple selection properly, somehow the code degenerates"
   href="https://bugs.llvm.org/show_bug.cgi?id=47237">47237</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Failure to optimize simple selection properly, somehow the code degenerates
          </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>Scalar Optimizations
          </td>
        </tr>

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

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

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>int f(int x, int y)
{
    return (x & y) == 0 ? x & ~y : x;
}

GCC outputs this :

f(int, int):
  andn edx, esi, edi
  mov eax, edi
  test edi, esi
  cmove eax, edx
  ret

And LLVM outputs this :

f(int, int): # @f(int, int)
  mov ecx, esi
  and ecx, edi
  not esi
  xor eax, eax
  cmp ecx, 1
  sbb eax, eax
  not eax
  or eax, esi
  and eax, edi
  ret

Most likely some sort of transformation in LLVM makes this code completely
degenerate into the result given here.</pre>
        </div>
      </p>


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