[PATCH 2/5] powerpc64-aix processing xlC generated line table

[Raunaq 12 <raunaq12 at in dot ibm dot com>]

xlc generated binaries have a line table which is not the same as GCC.
GCC compiled binaries have an extra line entry in the line table to
signify start of a function whereas xlc does not have this entry.

Due to this difference, commands like break <function name> and
list <function name> give wrong results.

To fix this issue I have written a function modify_xlc_linenos
which will add a line table entry at the function start points
if there is no extra entry in the line table as in the case of xlc.

Hence,
breakpoints and listing functions will work as expected even for xlc
compiled binaries.

---
ChangeLog :-
* xcoffread.c (modify_xlc_linenos): New function to modify xlc
generated linetables.
(process_linenos): make calls to the 'modify_xlc_linenos' to correctly
process linenos is case of xlc compiled binaries.
---
./gdb/xcoffread.c
===================================================================
--- ./gdb.orig/xcoffread.c
+++ ./gdb/xcoffread.c
@@ -241,6 +241,8 @@

 static struct linetable *arrange_linetable (struct linetable *);

+static struct linetable *modify_xlc_linenos (struct linetable *);
+
 static void record_include_end (struct coff_symbol *);

 static void process_linenos (CORE_ADDR, CORE_ADDR);
@@ -589,6 +591,24 @@
     }
 }

+/* xlc compiled binaries have one less entry in the line table.
+   So the function entry lines marked as line number equal to 0
+   will be retained in the line table with line numbers equal
+   to its succeeding line table entry.	*/
+
+static struct linetable *
+modify_xlc_linenos (struct linetable *lineTb)
+{
+ int jj;
+ for (jj = 0; jj < lineTb->nitems; jj++)
+  {
+   if (lineTb->item[jj].line == 0 && (lineTb->item[jj].pc
+                                    != lineTb->item[jj + 1].pc))
+        lineTb->item[jj].line = lineTb->item[jj + 1].line;
+  }
+ return lineTb;
+}
+
 /* Global variable to pass the psymtab down to all the routines involved
    in psymtab to symtab processing.  */
 static struct partial_symtab *this_symtab_psymtab;
@@ -698,10 +718,14 @@

       lv = main_subfile.line_vector;

+      /* Add extra line entry in case of xlc compiled binaries.	*/
+
+      lineTb = modify_xlc_linenos (lv);
+
       /* Line numbers are not necessarily ordered.  xlc compilation will
          put static function to the end.  */

-      lineTb = arrange_linetable (lv);
+      lineTb = arrange_linetable (lineTb);
       if (lv == lineTb)
 	{
 	  current_subfile->line_vector = (struct linetable *)
@@ -730,10 +754,14 @@

 	  lv = (inclTable[ii].subfile)->line_vector;

+          /* Add extra line entry in case of xlc compiled binaries */
+
+          lineTb = modify_xlc_linenos (lv);
+
 	  /* Line numbers are not necessarily ordered.  xlc compilation will
 	     put static function to the end.  */

-	  lineTb = arrange_linetable (lv);
+	  lineTb = arrange_linetable (lineTb);

 	  push_subfile ();

---