Re: [RFC] Move the frame zero PC check earlier

[Daniel Jacobowitz <drow@false.org>]

On Thu, May 11, 2006 at 03:24:31PM -0700, Jim Blandy wrote:
> 
> It looks good to me.  I'm just curious why we even bother looking up
> the frame type for the older frame whose PC is zero.  (I understand
> this test is inherited from the existing code.)

You've gotta.  It looks like this:

#0 somefunc ()
#1 <signal handler called>
#2 0x00000000 in Nothing At All
#3 function_which_calls_its_arg (arg = (void (*)()) 0x00000000)
#4 main ()

There was a check for this at some point in the distant past - I
believe it was committed, not just proposed - which didn't do this.
Ergo signull.exp.

Er... wait a second!  You're talking about a different frame than I am,
aren't you?  Do you mean this?

+  if (prev_frame->level > 0
+      && get_frame_type (this_frame) == NORMAL_FRAME
+      && get_frame_pc (prev_frame) == 0)

In which case we could do this even earlier.  Can there be sigtramp or
dummy frames which have pc == 0?

-- 
Daniel Jacobowitz
CodeSourcery