[RFA] Fix stack backtraces on 26-bit ARM

[Ben Harris <bjh21@cam.ac.uk>]

I've got an assignment signed, and commit access, so can someone approve
this now?

I'm trying to make GDB 5.0 work on NetBSD/arm26.  One problem I've run
into is that even with "set apcs32 0", stack backtraces include flags in
the program counter for all frames apart from the top one.  I think this
patch fixes the problem by using arm_addr_bits_remove() to clean up the
PC fetched from a stack frame.  I'm not in a position to check this still
works on arm32 and thumb.

ChangeLog entry:
2001-11-20  Ben Harris  <bjh21@netbsd.org>

	* arm-tdep.c (arm_frame_saved_pc): Use arm_addr_bits_remove to
	clean the PC.  Necessary for backtraces in 26-bit modes.

Patch:
*** arm-tdep.c  2000/07/26 00:32:33     1.1.1.1
--- arm-tdep.c  2001/10/20 16:40:16
*************** arm_frame_saved_pc (struct frame_info *f
*** 1019,1025 ****
  #endif
      {
 	CORE_ADDR pc = arm_find_callers_reg (fi, LR_REGNUM);
!	return IS_THUMB_ADDR (pc) ? UNMAKE_THUMB_ADDR (pc) : pc;
      }
  }

--- 1021,1027 ----
  #endif
      {
 	CORE_ADDR pc = arm_find_callers_reg (fi, LR_REGNUM);
!	return arm_addr_bits_remove(pc);
      }
  }

-- 
Ben Harris                                                   <bjh21@netbsd.org>
Portmaster, NetBSD/arm26               <URL:http://www.netbsd.org/Ports/arm26/>