[Bug c/78807] New: Loop optimization trigger bus error

[m.gcc.gnu.org at alias dot viem.se]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78807

            Bug ID: 78807
           Summary: Loop optimization trigger bus error
           Product: gcc
           Version: 5.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: m.gcc.gnu.org at alias dot viem.se
  Target Milestone: ---

Created attachment 40331
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40331&action=edit
Test program

With GCC 5.3.0 on Solaris 11 the below program ends due to bus error on sparc.
Turning of tree-loop optimizations with either of the below avoids bus error:
-fvect-cost-model=cheap
-fno-tree-loop-distribute-patterns
-fno-tree-loop-vectorize

=== bug.c ===
/*
$ gcc -m64 -O3 -fPIC -o bug bug.c

$ ./bug
Bus Error (core dumped)
*/

inline void g(unsigned size, unsigned x[], unsigned y[])
{
  unsigned i;
  for (i = 0; i < size; i++)
  {
    x[i] |= y[i];
  }
  for (i = 0; i < size; i++)
  {
    y[i] = 0;
  }
}

struct A
{
  long a; // Make struct A 8 byte aligned
  int b;  // Make x[] not 8 byte aligned
  unsigned x[6];
  unsigned y[6];
};

void f(struct A* a)
{
  g(6, a->x, a->y);
}

int
main()
{
  struct A a;
  f(&a);
  return 0;
}

=== END of bug.c ===