[Bug tree-optimization/68248] New: ICE on valid code at -O3 on x86_64-linux-gnu in uniform_vector_p, at tree.c:10807

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68248

            Bug ID: 68248
           Summary: ICE on valid code at -O3 on x86_64-linux-gnu in
                    uniform_vector_p, at tree.c:10807
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk at
-O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It is a regression from 5.2.x.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-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 6.0.0 20151107 (experimental) [trunk revision 229929] (GCC) 
$ 
$ gcc-trunk -O2 -c small.c
$ gcc-5.2 -O3 -c small.c
$ 
$ gcc-trunk -O3 -c small.c
small.c: In function ‘fn2’:
small.c:10:1: internal compiler error: in uniform_vector_p, at tree.c:10807
 fn2 ()
 ^

0xd6841f uniform_vector_p(tree_node const*)
        ../../gcc-trunk/gcc/tree.c:10807
0xcf9c9c expand_vector_operations_1
        ../../gcc-trunk/gcc/tree-vect-generic.c:1530
0xcf9c9c expand_vector_operations
        ../../gcc-trunk/gcc/tree-vect-generic.c:1732
0xcf9c9c execute
        ../../gcc-trunk/gcc/tree-vect-generic.c:1816
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;

int
fn1 (int p1)
{
  return a > 0 ? p1 : p1 >> a;
}

void
fn2 ()
{
  char e;
  for (; c; c++)
    {
      e = fn1 (!d ^ 2);
      b ^= e;
    }
}