[Bug c/86618] New: tree-vect-stmts.c:3340: ubsan error

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86618

            Bug ID: 86618
           Summary: tree-vect-stmts.c:3340: ubsan error
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

The following C code 

register struct a *b asm("%r15");
struct a {
  double *c
} d() {
  (*b).c[1] = copysign(1, (*b).c[1]);
  (*b).c[0] = copysign(0, (*b).c[0]);
}

Seems to generate a new runtime error on a ubsan verison of gcc trunk

../results.262549.ubsan/bin/gcc
../results.262835.ubsan/bin/gcc
../../trunk/gcc/tree-vect-stmts.c:3340:19: runtime error: member access within
n
ull pointer of type 'struct _loop_vec_info'

So the error seems to appeared between revisions 262549 and 262835.