check section overlap on relocatable links

[Nathan Sidwell <nathan at codesourcery dot com>]

This patch allows section overlap to be checked on a relocatable link.  Usually
this is a silly thing to do, because all output sections are placed at 0.
However, for vxworks images it can be useful, as a non-default linker script may
be being used to place sections sequentially.

The patch changes the check_section_addresses flag to be trivalued, so we can
distinguish 'default' from explicitly off and explicitly on.  When defaulted we
disable checking on relocatable linking (but it remains enabled on
non-relocatable links).  Thus preserving the existing default behaviour.

tested in powerpc-elf.  ok?

nathan
-- 
Nathan Sidwell    ::   http://www.codesourcery.com   ::         CodeSourcery

2009-01-21  Nathan Sidwell  <nathan@codesourcery.com>

	* lexsup.c (parse_args): Set check_section_addresses to 1 or 0.
	* ld.h (args_type): Make check_section_addresses a char.
	ldlang.c (lang_process): Don't consider relocatable flag when
	checking for overlap.
	* ldmain.c (main): Default check_section_addresses to -1. Check it
	for relocatable links.
	* ld.texinfo (--check-sections): Update documentation.

Index: ld.h
===================================================================
RCS file: /cvs/src/src/ld/ld.h,v
retrieving revision 1.41
diff -c -3 -p -r1.41 ld.h
*** ld.h	31 May 2008 16:35:56 -0000	1.41
--- ld.h	21 Jan 2009 12:21:52 -0000
*************** typedef struct {
*** 167,176 ****
       search.  */
    bfd_boolean warn_search_mismatch;
  
! 
!   /* If TRUE (the default) check section addresses, once compute,
!      fpor overlaps.  */
!   bfd_boolean check_section_addresses;
  
    /* If TRUE allow the linking of input files in an unknown architecture
       assuming that the user knows what they are doing.  This was the old
--- 167,175 ----
       search.  */
    bfd_boolean warn_search_mismatch;
  
!   /* If non-zero check section addresses, once computed,
!      for overlaps.  Relocatable links only check when this is > 0.  */
!   signed char check_section_addresses;
  
    /* If TRUE allow the linking of input files in an unknown architecture
       assuming that the user knows what they are doing.  This was the old
Index: ld.texinfo
===================================================================
RCS file: /cvs/src/src/ld/ld.texinfo,v
retrieving revision 1.226
diff -c -3 -p -r1.226 ld.texinfo
*** ld.texinfo	16 Jan 2009 14:14:06 -0000	1.226
--- ld.texinfo	21 Jan 2009 12:22:01 -0000
*************** perform this check, and if it finds any 
*** 1205,1210 ****
--- 1205,1213 ----
  suitable error messages.  The linker does know about, and does make
  allowances for sections in overlays.  The default behaviour can be
  restored by using the command line switch @option{--check-sections}.
+ Section overlap is not usually checked for relocatable links.  You can
+ force checking in that case by using the @option{--check-sections}
+ option.
  
  @cindex cross reference table
  @kindex --cref
Index: ldlang.c
===================================================================
RCS file: /cvs/src/src/ld/ldlang.c,v
retrieving revision 1.298
diff -c -3 -p -r1.298 ldlang.c
*** ldlang.c	26 Nov 2008 01:04:17 -0000	1.298
--- ldlang.c	21 Jan 2009 12:22:03 -0000
*************** lang_process (void)
*** 6225,6232 ****
    ldemul_finish ();
  
    /* Make sure that the section addresses make sense.  */
!   if (! link_info.relocatable
!       && command_line.check_section_addresses)
      lang_check_section_addresses ();
  
    lang_end ();
--- 6225,6231 ----
    ldemul_finish ();
  
    /* Make sure that the section addresses make sense.  */
!   if (command_line.check_section_addresses)
      lang_check_section_addresses ();
  
    lang_end ();
Index: ldmain.c
===================================================================
RCS file: /cvs/src/src/ld/ldmain.c,v
retrieving revision 1.133
diff -c -3 -p -r1.133 ldmain.c
*** ldmain.c	17 Aug 2008 03:12:50 -0000	1.133
--- ldmain.c	21 Jan 2009 12:22:04 -0000
*************** main (int argc, char **argv)
*** 251,257 ****
  
    command_line.warn_mismatch = TRUE;
    command_line.warn_search_mismatch = TRUE;
!   command_line.check_section_addresses = TRUE;
  
    /* We initialize DEMANGLING based on the environment variable
       COLLECT_NO_DEMANGLE.  The gcc collect2 program will demangle the
--- 251,257 ----
  
    command_line.warn_mismatch = TRUE;
    command_line.warn_search_mismatch = TRUE;
!   command_line.check_section_addresses = -1;
  
    /* We initialize DEMANGLING based on the environment variable
       COLLECT_NO_DEMANGLE.  The gcc collect2 program will demangle the
*************** main (int argc, char **argv)
*** 292,297 ****
--- 292,299 ----
  
    if (link_info.relocatable)
      {
+       if (command_line.check_section_addresses < 0)
+ 	command_line.check_section_addresses = 0;
        if (command_line.relax)
  	einfo (_("%P%F: --relax and -r may not be used together\n"));
        if (link_info.shared)
Index: lexsup.c
===================================================================
RCS file: /cvs/src/src/ld/lexsup.c,v
retrieving revision 1.108
diff -c -3 -p -r1.108 lexsup.c
*** lexsup.c	16 Jan 2009 14:14:06 -0000	1.108
--- lexsup.c	21 Jan 2009 12:22:06 -0000
*************** parse_args (unsigned argc, char **argv)
*** 1411,1420 ****
  	    config.split_by_file = 1;
  	  break;
  	case OPTION_CHECK_SECTIONS:
! 	  command_line.check_section_addresses = TRUE;
  	  break;
  	case OPTION_NO_CHECK_SECTIONS:
! 	  command_line.check_section_addresses = FALSE;
  	  break;
  	case OPTION_ACCEPT_UNKNOWN_INPUT_ARCH:
  	  command_line.accept_unknown_input_arch = TRUE;
--- 1411,1420 ----
  	    config.split_by_file = 1;
  	  break;
  	case OPTION_CHECK_SECTIONS:
! 	  command_line.check_section_addresses = 1;
  	  break;
  	case OPTION_NO_CHECK_SECTIONS:
! 	  command_line.check_section_addresses = 0;
  	  break;
  	case OPTION_ACCEPT_UNKNOWN_INPUT_ARCH:
  	  command_line.accept_unknown_input_arch = TRUE;