[Bug tree-optimization/68327] New: ICE on valid code at -O3 on x86_64-linux-gnu in vect_is_simple_use, at tree-vect-stmts.c:8562

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68327

            Bug ID: 68327
           Summary: ICE on valid code at -O3 on x86_64-linux-gnu in
                    vect_is_simple_use, at tree-vect-stmts.c:8562
           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 20151112 (experimental) [trunk revision 230270] (GCC) 
$ 
$ gcc-trunk -O2 -c small.c
$ gcc-5.2 -O3 -c small.c
$ 
$ gcc-trunk -O3 -c small.c
small.c: In function ‘fn1’:
small.c:5:1: internal compiler error: in vect_is_simple_use, at
tree-vect-stmts.c:8562
 fn1 ()
 ^

0xd1c930 vect_is_simple_use(tree_node*, vec_info*, gimple**, vect_def_type*,
tree_node**)
        ../../gcc-trunk/gcc/tree-vect-stmts.c:8562
0x5a6d70 vect_determine_vectorization_factor
        ../../gcc-trunk/gcc/tree-vect-loop.c:612
0xd3f78d vect_analyze_loop_2
        ../../gcc-trunk/gcc/tree-vect-loop.c:1843
0xd3f78d vect_analyze_loop(loop*)
        ../../gcc-trunk/gcc/tree-vect-loop.c:2121
0xd5499f vectorize_loops()
        ../../gcc-trunk/gcc/tree-vectorizer.c:517
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, d;
char b, c;

void
fn1 ()
{
  int i = 0;
  for (; i < 1; i++)
    d = 1;
  for (; b; b++) 
    a = 1 && (d & b);
}