Answering to myself.
Samuel Thibault, le Thu 14 Jun 2007 16:57:29 +0200, a écrit :
> Thomas Schwinge, le Thu 14 Jun 2007 16:42:10 +0200, a écrit :
> > From the quick glance I had, the problem is that MIG only handles data
> > structures via the `vm_address_t' type, whereas in the C code those
> > are pointers to structures.
>
> But if I understand correctly, the problem is that doing this:
>
> > +typedef vm_offset_t __attribute__ ((__may_alias__)) vm_address_t;
>
> will make vm_offset_t alias anybody, but not the content it is referring
> to.
Actually, I asked a guy that really knows such things, and the content
itself is not a problem: casting its address into an integer and giving
it somewhere else forces the compiler to assume it will be dereferenced
there.
Now, making vm_address_t alias everybody will probably make the warning
and potential bugs disappear, but it will restrict optimizations in
other places for instance, while writing
void *new_buf = old_buf + old_buf_len; /* First try. */
vm_address_t _new_buf = (vm_address_t) new_buf;
zerr = vm_allocate (mach_task_self (),
&_new_buf, new_buf_len - old_buf_len,
0);
new_buf = (void *) _new_buf;
is maybe a bit more verbose, but is correct.
Samuel
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