[Bug target/65408] powerpc64 function argument passing may access invalid memory

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65408

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note that code quality is an issue here as well.  Cases to consider are

struct test obj;

void foo()
{
  func (obj);
}

and

void foo()
{
  struct test obj;
  func (obj);
}

and

void foo (struct test obj)
{
  func (obj);
}

where we might (or might not) be sure that there is at least one 'int' mapped
after 'obj' (not for the global var case at least - but I'm less sure about
the other two cases (red zone? return address?))