<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 by LTO on x86_64-linux-gnu in 64-bit mode"
   href="http://llvm.org/bugs/show_bug.cgi?id=19072">19072</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>wrong code by LTO 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 when using LTO on
x86_64-linux-gnu in 64-bit mode (but not 32-bit mode). 

$ clang-trunk -v
clang version 3.5.0 (trunk 203119)
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 -O0 fn1.c fn2.c fn3.c main.c
$ a.out
0
$ clang-trunk -flto -O0 -c fn1.c
$ clang-trunk -flto -O1 -c fn2.c
$ clang-trunk -flto -O0 -c fn3.c
$ clang-trunk -flto -O0 -c main.c 
$ clang-trunk -flto -O1 fn1.o fn2.o fn3.o main.o
$ a.out
1293820360


$ cat fn1.c
extern int d;

void
fn1 (int p)
{
  if (!p)
    d = 0;
}
$ cat fn2.c
extern void fn1 (int); 
extern short b;

void
fn2 (void)
{
  for (b = 1; b; b++)
    fn1 (b);
}
$ cat fn3.c
extern void fn2 (void); 
extern volatile int c;
extern int d;

void
fn3 (void)
{
  fn2 ();
  int e = 0, t;
  if (d)
    {
      t = e || e ? 0 : e;
      c;
    }
}
$ cat main.c
extern int printf (const char *, ...);
extern void fn3 (void);

int a[6];
short b; 
volatile int c;
int d = 1; 

int
main ()
{
  a[1] = 0;
  fn3 ();
  printf ("%d\n", a[a[0]]);
  return 0;
}</pre>
        </div>
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