<html>
    <head>
      <base href="http://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 --- - wrong code at -O3 on x86_64-linux-gnu (affecting trunk and 3.3)"
   href="http://llvm.org/bugs/show_bug.cgi?id=18143">18143</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>wrong code at -O3 on x86_64-linux-gnu (affecting trunk and 3.3)
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>-New Bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>su@cs.ucdavis.edu
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The following code is miscompiled by the current clang trunk and clang 3.3 on
x86_64-linux-gnu at -O3 in both 32-bit and 64-bit modes.

This is a regression from clang 3.2. 

$ clang-trunk -v
clang version 3.5 (trunk 196455)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.3
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6

$ clang-trunk -O2 small.c; a.out
1
$ clang-3.2 -O3 small.c; a.out
1

$ clang-trunk -O3 small.c; a.out
2
$ clang-3.3 -O3 small.c; a.out
2

$ gcc-trunk -O3 small.c; a.out
1
$ icc -O3 small.c; a.out
1



---------------------------------


int printf (const char *, ...);

int a[2] = {0, 1}, b, c[1], *d = &c[0], e, f;

int
main ()
{
  int *g = &c[0];
  for (b = 0; b < 1; b++)
    {
      if (a[1])
    break;
      g = 0;
    }
  f = (&e == g) + 1;
  *d = f;
  printf ("%d\n", c[0]);
  return 0;
}</pre>
        </div>
      </p>
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