[Bug tree-optimization/60452] New: wrong code at -O1 and above on x86_64-linux-gnu (affecting trunk and 4.8.x)

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60452

            Bug ID: 60452
           Summary: wrong code at -O1 and above on x86_64-linux-gnu
                    (affecting trunk and 4.8.x)
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The current gcc trunk and 4.8.x mis-compile the following code on x86_64-linux
at -O1 in both 32-bit and 64-bit modes. 

This is a regression from 4.7.x. 


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.9.0 20140306 (experimental) [trunk revision 208366] (GCC) 
$ 
$ gcc-trunk -O0 small.c; a.out
$ gcc-trunk -O2 small.c; a.out
$ gcc-4.7.3 -O1 small.c; a.out
$ 
$ gcc-trunk -O1 small.c; a.out
Segmentation fault (core dumped)
$ gcc-4.8.2 -O1 small.c; a.out
Segmentation fault (core dumped)
$ 


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


int a, c, d;
short b;

void
fn1 (int p)
{
}

int
fn2 ()
{
  return 0;
}

int
main ()
{
  int e[2] = { 0, 0 };
  for (; b < 1; b++)
    {
      for (; c;)
    if (e[0])
      break;
      fn1 (e[b]);
      for (; c; c++)
    e[0] = 0;
      d = fn2 ();
      if (b == (d | 2837))
    a = e[b];
    }
  return 0;
}