[Bug tree-optimization/126729] New: [17 Regression] factor load does not handle scalar_storage_order correctly.

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126729

            Bug ID: 126729
           Summary: [17 Regression] factor load does not handle
                    scalar_storage_order  correctly.
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
struct S0 { int a; int v; }
__attribute__((scalar_storage_order("little-endian")));
union U0 { struct S0 s; int i[2]; }
__attribute__((scalar_storage_order("little-endian")));
struct S1 { int a; int v; }
__attribute__((scalar_storage_order("big-endian")));
union U1 { struct S1 s; int i[2]; }
__attribute__((scalar_storage_order("big-endian")));


int f(void *a, bool b, bool bb)
{
  if (b)
  {
    union U0 t = *((union U0*)a);
    if (bb)
      return t.i[0];
    return t.s.a;
  }
  {
    union U1 t = *((union U1*)a);
    if (bb)
      return t.i[0];
    return t.s.a;
  }
}
```

There should be a bytswap on either of the branches but currently there is not.