Andrew Haley wrote:
Null-terminating the call stack is too well-established practice to be changed now.
Which does not mean that the mistake should hold people back. This is just one of the mistakes in the x86-64 ABI. It was copied from x86 and it was wrong there already.
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,
Of course it means that.
The right way to fix the ABI is to specify that %ebp mustn't be [mis]used in this way, not to add a bunch more unwinder data.
Nope. The right way is to specify things like backtraces with the adequate mechanism. I fully support adding the Dwarf3 unwinder requirements.
-- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
