[Bug tree-optimization/58921] New: ICE with segfault on valid code at -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58921

            Bug ID: 58921
           Summary: ICE with segfault on valid code at -O3 on
                    x86_64-linux-gnu
           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 at
-O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes. 

It is a regression from 4.8.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
--enable-languages=c,c++,objc,obj-c++,fortran,lto --disable-werror
--enable-checking=none --with-gmp=/usr/local/gcc-trunk
--with-mpfr=/usr/local/gcc-trunk --with-mpc=/usr/local/gcc-trunk
--with-cloog=/usr/local/gcc-trunk --prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20131029 (experimental) [trunk revision 204186] (GCC) 
$ 
$ gcc-trunk -O2 small.c
$ gcc-4.8 -O3 small.c
$ 
$ gcc-trunk -O3 small.c
small.c: In function ‘fn1’:
small.c:5:1: internal compiler error: Segmentation fault
 fn1 ()
 ^
0x81d4af crash_signal
    ../../gcc-trunk/gcc/toplev.c:334
0x967417 gimple_code
    ../../gcc-trunk/gcc/gimple.h:1222
0x967417 vect_get_vec_def_for_operand(tree_node*, gimple_statement_d*,
tree_node**)
    ../../gcc-trunk/gcc/tree-vect-stmts.c:1438
0x9678e8 vect_get_vec_defs(tree_node*, tree_node*, gimple_statement_d*,
vec<tree_node*, va_heap, vl_ptr>*, vec<tree_node*, va_heap, vl_ptr>*,
_slp_tree*, int)
    ../../gcc-trunk/gcc/tree-vect-stmts.c:1627
0x96c267 vectorizable_operation
    ../../gcc-trunk/gcc/tree-vect-stmts.c:3779
0x972b64 vect_transform_stmt(gimple_statement_d*, gimple_stmt_iterator_d*,
bool*, _slp_tree*, _slp_instance*)
    ../../gcc-trunk/gcc/tree-vect-stmts.c:5951
0x97711b vect_transform_loop(_loop_vec_info*)
    ../../gcc-trunk/gcc/tree-vect-loop.c:5880
0x98f4d6 vectorize_loops()
    ../../gcc-trunk/gcc/tree-vectorizer.c:373
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[7];
int b;

void
fn1 ()
{
  for (; b; b++)
    a[b] = ((a[b] <= 0) == (a[0] != 0));
}

int
main ()
{
  return 0;
}