Re: RFA: ia64 portion of libunwind patch

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Fri, 31 Oct 2003 15:46:19 -0500, Andrew Cagney <ac131313@redhat.com> said:

  >>  The way the libunwind interface works nowadays, the only
  >> buffering that is strictly needed is for the unwind info of the
  >> procedure being looked up (which usually has a size of the order
  >> of tens of bytes).  But this would require doing a binary search
  >> on the unwind-table in the target space, which might be rather
  >> slow (there is one 24-byte entry in this table per procedure).
  >> Thus, it might be easier (and certainly faster) to buffer the
  >> unwind table inside gdb.

  Andrew> Given a PC, how is the table located?  I see the change does
  Andrew> roughly: pc -> section -> objfile -> BFD -> unwind segment
  Andrew> -> paddr/size?

That's about right.

  Andrew> (GDB appears to have a log2 (128k of unwind section / 24) =
  Andrew> ~14) I'm guessing that the binary search involves about 14
  Andrew> fetches and provided they are serviced from a cache they
  Andrew> will be very efficient.

Yup.

	--david