collect2 library file extension search order (PR target/18720)

[David Edelsohn <dje at watson dot ibm dot com>]

	On AIX, the -brtl linker option to enable runtime linking changes
the ordering of shared library file extensions to search for ".so" before
".a".  This patch changes the AIX-only portion of GCC's collect2 linker
wrapper to match that behavior.

Bootstrapped and regression tested on powerpc-ibm-aix5.2.0.0.  Committed
to mainline.

I will bootstrap with GCC-3.4 branch and commit there when successful.

David

	PR target/18720
	* collect2.c (main): Set aixrtl_flag for -brtl option.
	(resolve_lib_name): Search for .so file extension before .a
	if aixrtl_flag set.

Index: collect2.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/collect2.c,v
retrieving revision 1.167
diff -c -p -r1.167 collect2.c
*** collect2.c	9 Nov 2004 10:12:15 -0000	1.167
--- collect2.c	9 Jan 2005 21:57:18 -0000
*************** static const char *demangle_flag;
*** 185,190 ****
--- 185,191 ----
  #ifdef COLLECT_EXPORT_LIST
  static int export_flag;                 /* true if -bE */
  static int aix64_flag;			/* true if -b64 */
+ static int aixrtl_flag;			/* true if -brtl */
  #endif
  
  int debug;				/* true if -debug */
*************** static struct path_prefix cmdline_lib_di
*** 242,248 ****
  static struct path_prefix libpath_lib_dirs; /* directories in LIBPATH */
  static struct path_prefix *libpaths[3] = {&cmdline_lib_dirs,
  					  &libpath_lib_dirs, NULL};
- static const char *const libexts[3] = {"a", "so", NULL};  /* possible library extensions */
  #endif
  
  static void handler (int);
--- 243,248 ----
*************** main (int argc, char **argv)
*** 1087,1092 ****
--- 1087,1094 ----
                  export_flag = 1;
  	      else if (arg[2] == '6' && arg[3] == '4')
  		aix64_flag = 1;
+ 	      else if (arg[2] == 'r' && arg[3] == 't' && arg[4] == 'l')
+ 		aixrtl_flag = 1;
  	      break;
  #endif
  
*************** resolve_lib_name (const char *name)
*** 2594,2599 ****
--- 2596,2603 ----
  {
    char *lib_buf;
    int i, j, l = 0;
+   /* Library extensions for AIX dynamic linking.  */
+   const char * const libexts[2] = {"a", "so"};
  
    for (i = 0; libpaths[i]; i++)
      if (libpaths[i]->max_len > l)
*************** resolve_lib_name (const char *name)
*** 2612,2625 ****
  	  const char *p = "";
  	  if (list->prefix[strlen(list->prefix)-1] != '/')
  	    p = "/";
! 	  for (j = 0; libexts[j]; j++)
  	    {
  	      sprintf (lib_buf, "%s%slib%s.%s",
! 		       list->prefix, p, name, libexts[j]);
! if (debug) fprintf (stderr, "searching for: %s\n", lib_buf);
  	      if (file_exists (lib_buf))
  		{
! if (debug) fprintf (stderr, "found: %s\n", lib_buf);
  		  return (lib_buf);
  		}
  	    }
--- 2616,2630 ----
  	  const char *p = "";
  	  if (list->prefix[strlen(list->prefix)-1] != '/')
  	    p = "/";
! 	  for (j = 0; j < 2; j++)
  	    {
  	      sprintf (lib_buf, "%s%slib%s.%s",
! 		       list->prefix, p, name,
! 		       libexts[(j + aixrtl_flag) % 2]);
! 	      if (debug) fprintf (stderr, "searching for: %s\n", lib_buf);
  	      if (file_exists (lib_buf))
  		{
! 		  if (debug) fprintf (stderr, "found: %s\n", lib_buf);
  		  return (lib_buf);
  		}
  	    }