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List:       llvm-bugs
Subject:    [LLVMbugs] [Bug 21694] New: wrong code at -Os and above on x86_64-linux-gnu
From:       bugzilla-daemon () llvm ! org
Date:       2014-11-30 3:48:10
Message-ID: bug-21694-206 () http ! llvm ! org/bugs/
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--1417319290.ed2c8ebc1.22812
Date: Sat, 29 Nov 2014 21:48:10 -0600
MIME-Version: 1.0
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http://llvm.org/bugs/show_bug.cgi?id=21694

            Bug ID: 21694
           Summary: wrong code at -Os and above on x86_64-linux-gnu
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs@nondot.org
          Reporter: su@cs.ucdavis.edu
                CC: llvmbugs@cs.uiuc.edu
    Classification: Unclassified

The current clang trunk miscompiles the following code at -Os and above on
x86_64-linux-gnu in both 32-bit and 64-bit modes.

This is a regression from 3.5.0.  

$ clang-trunk -v
clang version 3.6.0 (trunk 222928)
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 -O1 small.c; a.out
$ clang-3.5.0 -Os small.c; a.out
$ 
$ clang-trunk -Os small.c
$ a.out
Aborted (core dumped)
$ 


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


int a = 1, c, *f = &c;
int volatile e;
short b, *d = &b;

static int
fn1 (int *p)
{
  for (b = 1; b != 4; b += 5)
    if (*p)
      e = 0;
    else
      return 0;
  *f = *d;
  return 0;
}

int
main ()
{
  int *g = &a;
  fn1 (g);

  if (c != 4) 
    __builtin_abort (); 

  return 0;
}

-- 
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--1417319290.ed2c8ebc1.22812
Date: Sat, 29 Nov 2014 21:48:10 -0600
MIME-Version: 1.0
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<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 -Os and above on x86_64-linux-gnu"
   href="http://llvm.org/bugs/show_bug.cgi?id=21694">21694</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>wrong code at -Os and above on x86_64-linux-gnu
          </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&#64;nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>su&#64;cs.ucdavis.edu
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs&#64;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 -Os and above on
x86_64-linux-gnu in both 32-bit and 64-bit modes.

This is a regression from 3.5.0.  

$ clang-trunk -v
clang version 3.6.0 (trunk 222928)
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: .;&#64;m64
Candidate multilib: 32;&#64;m32
Selected multilib: .;&#64;m64
$ 
$ clang-trunk -O1 small.c; a.out
$ clang-3.5.0 -Os small.c; a.out
$ 
$ clang-trunk -Os small.c
$ a.out
Aborted (core dumped)
$ 


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


int a = 1, c, *f = &amp;c;
int volatile e;
short b, *d = &amp;b;

static int
fn1 (int *p)
{
  for (b = 1; b != 4; b += 5)
    if (*p)
      e = 0;
    else
      return 0;
  *f = *d;
  return 0;
}

int
main ()
{
  int *g = &amp;a;
  fn1 (g);

  if (c != 4) 
    __builtin_abort (); 

  return 0;
}</pre>
        </div>
      </p>
      <hr>
      <span>You are receiving this mail because:</span>
      
      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>

--1417319290.ed2c8ebc1.22812--


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