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Re: Unwinding CFI gcc practice of assumed `same value' regs
> Ian Lance Taylor writes:
> > Andrew Haley <aph@redhat.com> writes:
> >
> > > In practice, %ebp either points to a call frame -- not necessarily
> the
> > > most recent one -- or is null. I don't think that having an optional
> > > frame pointer mees you can use %ebp for anything random at all, but
> we
> > > need to make a clarification request of the ABI.
> >
> > I don't see that as feasible. If %ebp/%rbp may be used as a general
> > callee-saved register, then it can hold any value.
>
> Sure, we already know that, as has been clear. The question is *if*
> %rbp may be used as a general callee-saved register that can hold any
> value.
The amd64 ABI is specifically *designed* to allow this.
Mark