[hppa] FYI: confusion in unwind descriptor field meaning
Randolph Chung
randolph@tausq.org
Thu Nov 10 01:27:00 GMT 2005
Joel,
> This is really for anybody's FYI, and maybe Randolph if he'd like to
> dig in some of the issues with me.
>
> This is something I'm still working on, so I haven't verified my theory
> just yet. But I think there is a confusion in the meaning of Save_SP
> in the unwind descriptor. The document I have says:
>
> 18. Save_SP (bit 27): One if the entry value of SP is saved by this
> regions entry sequence in the current frame marker (current_SP - 4);
> zero otherwise.
>
> It doesn't say that the frame has a frame base register. For this, we
> have another field:
Be careful here, some of this is to work around gcc's interpretation of
these fields, which does not always correspond to the documentation. gcc
only uses a few of the bits in the unwind record.
Dave Anglin (pa gcc maintainer) is the expert on these issues.
I only have a few minutes now, will respond in more detail to your two
messages later this evening.
thanks and I do hope to have a little more time to start looking at gdb
again.
randolph
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