[RFA] Handle GPC specific name for main function

["Pierre Muller" <muller@ics.u-strasbg.fr>]

  This is my final patch to be able to
detect the fact that GPC was used to compile
the main procedure and set the name of that main
procedure (which is either "pascal_main_program"
or "_p__M0_main_program").

  The whole thread started with
http://sourceware.org/ml/gdb-patches/2007-09/msg00373.html

Is it OK to commit?

Pierre Muller
Pascal language maintainer.

ChangeLog entry:

2007-10-03  Pierre Muller  <muller@ics.u-strasbg.fr>

        * p-lang.h (pascal_main_name): New function.
        p-lang.c (GPC_P_INITIALIZE, GPC_MAIN_PROGRAM_NAME_1),
        (GPC_MAIN_PROGRAM_NAME_2): New char array constants
        corresponding to the three minimal symbols used
        by GPC compiler.
        (pascal_main_name): Try to find minimal symbol
        corresponding to the entry of GPC compiled programs.
        symtab.c: New include p-lang.h.
        (find_main_name): Try to find pascal specific main name
        by calling pascal_main_name.
        * Makefile.in (symtab.o): Add dependency on p-lang header.




Index: p-lang.h
===================================================================
RCS file: /cvs/src/src/gdb/p-lang.h,v
retrieving revision 1.12
diff -u -p -r1.12 p-lang.h
--- p-lang.h    23 Aug 2007 18:08:36 -0000      1.12
+++ p-lang.h    3 Oct 2007 09:21:58 -0000
@@ -21,6 +21,9 @@

 struct value;

+/* Defined in p-lang.c */
+extern char *pascal_main_name (void);
+
 extern int pascal_parse (void);        /* Defined in p-exp.y */

 extern void pascal_error (char *);     /* Defined in p-exp.y */
Index: p-lang.c
===================================================================
RCS file: /cvs/src/src/gdb/p-lang.c,v
retrieving revision 1.33
diff -u -p -r1.33 p-lang.c
--- p-lang.c    23 Sep 2007 16:25:05 -0000      1.33
+++ p-lang.c    3 Oct 2007 09:21:58 -0000
@@ -35,6 +35,63 @@
 extern void _initialize_pascal_language (void);


+/* All GPC versions until now (2007-09-27) also define a symbol called
+   '_p_initialize'. Check for the presence of this symbol first.  */
+ static const char GPC_P_INITIALIZE[]
+  = "_p_initialize";
+
+/* The name of the symbol that GPC uses as the name of the main
+   procedure (since version 20050212).  */
+static const char GPC_MAIN_PROGRAM_NAME_1[]
+  = "_p__M0_main_program";
+
+/* Older versions of GPC (versions older than 20050212) were using
+   a different name for the main procedure.  */
+static const char GPC_MAIN_PROGRAM_NAME_2[]
+  = "pascal_main_program";
+
+/* Function returning the special symbol name used
+   by GPC for the main procedure in the main program
+   if it is found in minimal symbol list.
+   This function tries to find minimal symbols generated by GPC
+   so that it finds the even if the program was compiled
+   without debugging information.
+   According to information supplied by Waldeck Hebisch,
+   this should work for all versions posterior to June 2000. */
+
+char *
+pascal_main_name (void)
+{
+  struct minimal_symbol *msym;
+
+  msym = lookup_minimal_symbol (GPC_P_INITIALIZE, NULL, NULL);
+
+ /*  If '_p_initialize' was not found,
+     the program doesn't seem to be compiled with GPC.
+     Thus default name "main" should work.  */
+  if (msym == NULL)
+    return NULL;
+
+  msym = lookup_minimal_symbol (GPC_MAIN_PROGRAM_NAME_1, NULL, NULL);
+
+  if (msym != NULL)
+    {
+      return (char *)GPC_MAIN_PROGRAM_NAME_1;
+    }
+
+  msym = lookup_minimal_symbol (GPC_MAIN_PROGRAM_NAME_2, NULL, NULL);
+
+  if (msym != NULL)
+    {
+      return (char *)GPC_MAIN_PROGRAM_NAME_2;
+    }
+
+/*  No known entry procedure found, use default 'main' name.
+    According to Waldek Hebish, this should not happen for any GPC version
+    after June 2000 and up to 2007-09-27.  */
+  return NULL;
+}
+
 /* Determines if type TYPE is a pascal string type.
    Returns 1 if the type is a known pascal type
    This function is used by p-valprint.c code to allow better string
display.
Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.165
diff -u -p -r1.165 symtab.c
--- symtab.c    24 Sep 2007 07:40:32 -0000      1.165
+++ symtab.c    3 Oct 2007 09:21:59 -0000
@@ -40,6 +40,7 @@
 #include "filenames.h"         /* for FILENAME_CMP */
 #include "objc-lang.h"
 #include "ada-lang.h"
+#include "p-lang.h"

 #include "hashtab.h"

@@ -4151,6 +4152,13 @@ find_main_name (void)
       return;
     }

+  new_main_name = pascal_main_name ();
+  if (new_main_name != NULL)
+    {
+      set_main_name (new_main_name);
+      return;
+    }
+
   /* The languages above didn't identify the name of the main procedure.
      Fallback to "main".  */
   set_main_name ("main");
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.939
diff -u -p -r1.939 Makefile.in
--- Makefile.in 27 Sep 2007 18:48:32 -0000      1.939
+++ Makefile.in 3 Oct 2007 09:22:00 -0000
@@ -2751,7 +2751,7 @@ symtab.o: symtab.c $(defs_h) $(symtab_h)
        $(filenames_h) $(objc_lang_h) $(ada_lang_h) $(hashtab_h) \
        $(gdb_obstack_h) $(block_h) $(dictionary_h) $(gdb_string_h) \
        $(gdb_stat_h) $(cp_abi_h) $(observer_h) $(gdb_assert_h) \
-       $(solist_h) $(ada_lang_h)
+       $(solist_h) $(p_lang_h)
 target.o: target.c $(defs_h) $(gdb_string_h) $(target_h) $(gdbcmd_h) \
        $(symtab_h) $(inferior_h) $(bfd_h) $(symfile_h) $(objfiles_h) \
        $(gdb_wait_h) $(dcache_h) $(regcache_h) $(gdb_assert_h) $(gdbcore_h)
\