<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 -O2 and -O3 on x86_64-linux-gnu in 64-bit mode"
   href="http://llvm.org/bugs/show_bug.cgi?id=21741">21741</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>wrong code at -O2 and -O3 on x86_64-linux-gnu in 64-bit mode
          </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 current clang trunk miscompiles the following code at -O2 and -O3 on
x86_64-linux-gnu in 64-bit mode (but not in 32-bit mode). 

This is a regression from 3.5.0. 

$ clang-trunk -v
clang version 3.6.0 (trunk 223263)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.8.1
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/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64

$ clang-trunk -m64 -Os small.c; a.out
$ clang-trunk -m32 -O2 small.c; a.out
$ clang-3.5.0 -m64 -O2 small.c; a.out

$ clang-trunk -m64 -O2 small.c
$ a.out
Segmentation fault (core dumped)



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


int a, b, c, d, e, h, k[4], l, n;
char f, m, g[3][5];

void
fn1 ()
{
  for (f = 2; f >= 0; f--)
    {
      k[f + d] = 0;
      for (h = 0; h < 2; h++)
    {
      for (; e < 2; e++)
        m = a;
      l = g[f][d + 1] & a & 1;
      n = k[0] >= 0 ? 1 : 1 >> b;
      if (n)
        break;
      for (c = 0; c < 1; c++)
        d = -5000000; 
    }
    }
}

int
main ()
{
  fn1 ();
  return 0;
}</pre>
        </div>
      </p>
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