Re: [patch/rfa] Signal trampoline unwinder for hppa-hpux

[Daniel Jacobowitz <drow@false.org>]

On Tue, May 25, 2004 at 10:36:09PM -0700, Randolph Chung wrote:
> > Yes, definitly.  Having to do instruction examination should be 
> > considered a last resource.
> 
> ok, this is checked in now too, but can someone please comment on this
> bit:
> 
> ================================================================
> Unfortunately this still fails a lot of the signal related testcases.
> It is not because of a problem with the signal unwinder though:
> 
> On HPUX-SOM, there is an export stub inserted into the call sequence in
> some cases; the export stub is hit on the return path from indirect
> function calls, and apparently on return from a signal handler. This 
> creates an extra frame in the backtrace, viz:
> 
> (gdb) bt
> #0  0x000029e4 in handle_USR1 (sig=0)
>     at ../../../gdb/gdb/testsuite/gdb.base/annota1.c:18
> #1  0x000029c8 in handle_USR1 ()
>     at ../../../gdb/gdb/testsuite/gdb.base/annota1.c:17
> #2  <signal handler called>
> #3  main () at ../../../gdb/gdb/testsuite/gdb.base/annota1.c:40
> 
> Frame 1 comes from the export stub. Because of this, the pattern
> matching in the backtrace test fails.  I am not sure if this is a
> problem with the test script or with the handling of export stubs -- am
> I supposed to somehow supress the export stub from showing up in the
> backtrace? (if so, how?)

Right now, we don't have any mechanism to hide frames.  I'm not sure
whether it's a desirable feature or not.  I've wanted it for C++
occasionally.

I wonder if GDB should have a single knob to switch between
"simplified" and more thorough/accurate display modes?  Could any of
the existing toggles be added to this?

-- 
Daniel Jacobowitz