Re: [PATCH] Remove zero PC check from blockframe.c:inside_main_func()

[Andrew Cagney <cagney at gnu dot org>]

>    Date: Sat, 13 Dec 2003 19:22:47 -0500
>    From: Andrew Cagney <cagney@gnu.org>
>
>    > RCS file: /cvs/src/src/gdb/frame.c,v
>    > retrieving revision 1.153
>    > diff -u -p -r1.153 frame.c
>    > --- frame.c 10 Dec 2003 17:40:42 -0000 1.153
>    > +++ frame.c 13 Dec 2003 21:47:43 -0000
>    > @@ -1732,6 +1732,7 @@ struct frame_info *
>    >  get_prev_frame (struct frame_info *this_frame)
>    >  {
>    >    struct frame_info *prev_frame;
>    > +  CORE_ADDR pc;
>    >  
>    >    if (frame_debug)
>    >      {
>    > @@ -1961,7 +1962,8 @@ get_prev_frame (struct frame_info *this_
>    >       because (well ignoring the PPC) a dummy frame can be located
>    >       using THIS_FRAME's frame ID.  */
>    >  
>    > -  if (frame_pc_unwind (this_frame) == 0)
>    > +  pc = frame_pc_unwind (this_frame);
>    > +  if (this_frame->level >= 0 && pc == 0)
>    >      {
>    >        /* The allocated PREV_FRAME will be reclaimed when the frame
>    >  	 obstack is next purged.
>
>    Can it be deleted?
>
> I think so.  I tested i386-unknown-freebsd4.7, i386-pc-solaris2.9,
> x86_64-unknown-freebsd5.2 and alpha-unknown-freenbsd5.2, and things
> didn't change.
>
>    This would likely affect the initial call sequence made to the unwinder 
>    - frame_pc_unwind may not be called first (?).  But I also think that 
>    the reason for insisting on an explicit pc unwind may have also been 
>    removed - the new code is written more robustly anyway.
>
> I think I agree.  So shall I remove the code?

Yes, just watch for comments claiming that the pc is unwound first 
though though.  I believe it's now really entirely determined by the 
per-architecture frame sniffers.

Andrew