[rfa/ppc] Return the dummy frame's saved pc

[Andrew Cagney <ac131313@redhat.com>]

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Hello,

The attached patch modifies rs6000_frame_saved_pc() so that when:

- a frame didn't save the PC (i.e., link register)
- the next inner most frame is a dummy

the dummy frame's link register is returned.

On a GNU/Linux PPC system (not sure which flavour but gcc is ``2.95.3'' 
:-), it fixes the following failures:

gdb.base/callfuncs.exp: backtrace after finish from nested call level 3
gdb.base/callfuncs.exp: backtrace after finish from nested call level 4
gdb.base/callfuncs.exp: backtrace at nested call level 2
gdb.base/callfuncs.exp: backtrace at nested call level 3
gdb.base/callfuncs.exp: backtrace at nested call level 4

Ok?

Andrew

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2002-09-24  Andrew Cagney  <ac131313@redhat.com>

	* rs6000-tdep.c (rs6000_frame_saved_pc): If the link register
	wasn't saved, and the next innermost frame is a dummy, return the
	dummy frame's link register.

Index: rs6000-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v
retrieving revision 1.82
diff -u -r1.82 rs6000-tdep.c
--- rs6000-tdep.c	17 Sep 2002 20:42:01 -0000	1.82
+++ rs6000-tdep.c	24 Sep 2002 14:06:50 -0000
@@ -1527,6 +1527,16 @@
       if (fi->next->signal_handler_caller)
 	return read_memory_addr (fi->next->frame + SIG_FRAME_LR_OFFSET,
 				 wordsize);
+      else if (PC_IN_CALL_DUMMY (get_next_frame (fi)->pc, 0, 0))
+	/* The link register wasn't saved by this frame and the next
+           (inner, newer) frame is a dummy.  Get the link register
+           value by unwinding it from that [dummy] frame.  */
+	{
+	  ULONGEST lr;
+	  frame_unwind_unsigned_register (get_next_frame (fi),
+					  tdep->ppc_lr_regnum, &lr);
+	  return lr;
+	}
       else
 	return read_memory_addr (FRAME_CHAIN (fi) + tdep->lr_frame_offset,
 				 wordsize);