2008-09-22  Andrew Stubbs  <ams@codesourcery.com>

	* frame.c (get_frame_register_bytes): Comment improvments.

Index: frame.c
===================================================================
RCS file: /cvs/src/src/gdb/frame.c,v
retrieving revision 1.252
diff -u -p -r1.252 frame.c
--- frame.c	19 Sep 2008 18:12:17 -0000	1.252
+++ frame.c	22 Sep 2008 13:12:09 -0000
@@ -806,13 +806,14 @@ get_frame_register_bytes (struct frame_i
       regnum++;
     }
 
-  /* Detect bad debug info.  */
+  /* Ensure that we will not read beyond the end of the register file.
+     This can only ever happen if the debug information is bad.  */
   maxsize = -offset;
   for (i = regnum; i < gdbarch_num_regs (gdbarch); i++)
     {
       int thissize = register_size (gdbarch, i);
       if (thissize == 0)
-	break;
+	break;	/* This register is not available on this architecture.  */
       maxsize += thissize;
     }
   if (len > maxsize)