Porting GDB to ia64-hpux

[Joel Brobecker <brobecker at adacore dot com>]

At long last, after having promised this a long time ago (this brings
memories of Australia, as I was spending time there when I first started
on this port), I am finally contributing this port.  It took a while,
because the first port I did (against GDB 6.3) had a few hacks in it
that I wasn't happy about.

This port is relatively clean, I believe.  There is one dark spot with
shared library support, which is currently native-only - if you build
GDB as a cross debugger to ia64-hpux, you won't get the shared libraries.
I think that this is an acceptable limitation, since I'm not planning on
supporting gdbserver-style remote debugging capabilities.  I did spend
a couple of hours exploring the idea of using solib-target, but there
were a couple of issues[1].

I was able to build tcl/expect on this platform, and thus was able to
run the testsuite.  Results are not stellar, but to my surprise, already
better than what I get on ia64-linux.  A large portion of the failures
are caused by known limitations / missing features in that port, which
I will detail a little bit below.  Results first:

        # of expected passes            10618
        # of unexpected failures        727
        # of expected failures          50
        # of untested testcases         105
        # of unresolved testcases       12
        # of unsupported tests          61

The entire patch series has also been tested on ia64-linux, with no
observed regression.

I'd like to commit this Thu or Fri in a week from now.

Known problems and missing features that are causing most of the failures:

  - core files are not supported (I know it's easy to add, but I just
    don't know how to!). If someone kindly helped, I would be happy
    to give it a crack - an interesting learning exercise.

  - The kernel on HP-UX does not allow the debugger to change the value
    of the BSP register, which makes it impossible to "pop" a register
    frame at the same time was pop the stack frame during a "return".
    This pretty much guaranties great chaos during a "return" (loss of
    synchronization between the call stack and the register stack).

  - Backtraces through signal handlers.

  - function-call parameter passing / return values: There are still
    some cases where we pass the parameters incorrectly.  But that's
    general to ia64, I think.

-- 
Joel

[1] Issues related to using solib-target with ia64-hpux:

    (a) I need the various hooks to setup the shared-lib notifications;

    (b) And next, it's not obvious how to map the info I get from
        the system back to the way the info is encoded in the
        TARGET_OBJECT_SHARED_LIBRARIES object. In particular, there are
        two segments (data and code) to consider when performing section
        relocation.  The second issue should be workable, but the first
        one is a bit more of an issue.