https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117634

            Bug ID: 117634
           Summary: memset/struct copy transformation into memset/memset
                    is not done if not address
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
struct S { char a[1024]; };
void f(void*);
void
f3 (struct S *b)
{
  struct S a;
  __builtin_memset (b, 0, sizeof (*b));
  a = *b;
  f(&a);
  f(b);
}
void
f4 (struct S *b)
{
  struct S a;
  __builtin_memset (b, 0, sizeof (*b));
  a = (struct S){};
  f(&a);
}

void
f5 ()
{
  struct S a, b;
  __builtin_memset (&b, 0, sizeof (b));
  a = b;
  f(&a);
  f(&b);
}
```

These all should be optimized to 2 memset. currently f5 (and f4 which is
already 2 memset) can be optimized to a memset via the code in
optimize_memcpy_to_memset but f3 is not handled.

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