[Bug middle-end/124261] Memory read disambiguated by clang but not by gcc

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124261

Drea Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

--- Comment #3 from Drea Pinski <pinskia at gcc dot gnu.org> ---
So if we thread the blocks we do the right thing:
```
struct a {int a, b,c,d,e,g;};
struct a ret();
void h();
int
test (int o)
{
        struct a aa,cc;
        struct a *bb = o ? &aa : &cc;
        int *p = o ? &aa.b : &cc.b;
        int *q = o ? &aa.a : &cc.a;
        *bb = ret ();
        *p = 12345;
        *q = 0;
        int t =  *p;
        if (o)  h();
        return t;
}
```

I wonder if we could do phiprop for stores. That would fix the orginal case I
think. But maybe there is some more complex case that makes a difference
though.