[Bug tree-optimization/59903] New: ICE on valid code at -O3 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=59903

            Bug ID: 59903
           Summary: ICE on valid code at -O3 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 following code causes an ICE when compiled with the current gcc trunk and
4.8.x at -O3 on x86_64-linux-gnu (in both 32-bit and 64-bit modes). 

It is a regression from 4.7.x.

I had hoped to reduce it further, but this is the simplest I could get.  

$ 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 20140121 (experimental) [trunk revision 206876] (GCC) 
$ 
$ gcc-trunk -O2 small.c; a.out
$ gcc-4.7.3 -O3 small.c; a.out
$ 
$ gcc-trunk -O3 small.c
small.c: In function ‘main’:
small.c:45:1: internal compiler error: Segmentation fault
 main ()
 ^
0x9bf4df crash_signal
    ../../gcc-trunk/gcc/toplev.c:337
0xbaaee3 tree_check
    ../../gcc-trunk/gcc/tree.h:2708
0xbaaee3 vect_transform_loop(_loop_vec_info*)
    ../../gcc-trunk/gcc/tree-vect-loop.c:5872
0xbc859d vectorize_loops()
    ../../gcc-trunk/gcc/tree-vectorizer.c:476
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


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


int a, b, c, d, e, f, g, h, i[3], l, m, n, o, p, q, r;

struct S0
{
  int f0;
  int f1;
  int f2;
  int f3;
} j;

static int
fn1 (int p1)
{
  return p1 || ((p1 > 0) > (e << 1)); 
}

static struct S0
fn2 (struct S0 p1)
{
  char s;
  struct S0 t = {0,0,0,0};
  int u = 2;
  for (;;)
    {
      if (i[0])
    break;
      for (m = 0; m < 4; m++)
    for (p1.f0 = 0; p1.f0 < 3; p1.f0++)
      {
        j = t;
        t.f3 = i[p1.f0];
        o = b || 1 >> b ? 0 : a < 0;
        q = 1 % d;
        if ((g < fn1 ((1 ^ (q & 1)) | n)) ^ u)
          j.f3 |= p % 2;
        s = j.f3 > 0 ? j.f3 : j.f3 << 1;
        r = l = s && p1.f1 * c;
        h = p1.f1;
      }
    }
  return p1;
}

int
main ()
{
  for (;f;)
    {
      struct S0 v = {0,0,0,0};
      fn2 (v);
      j.f3 = 0;
    }
  return 0;
}