Re: stripping debug info & local symbols

[Alan Modra <amodra at bigpond dot net dot au>]

On Wed, Jun 04, 2008 at 08:30:41AM +0100, Nathan Sidwell wrote:
> Alan Modra wrote:
> >On Tue, Jun 03, 2008 at 04:05:46PM +0100, Nathan Sidwell wrote:
> >>Nathan Sidwell wrote:
> >>>I'm trying to fix a bug where objcopy -g is breaking relocations in a 
> >>>relocatable vxworks executable.  The executable is generated by a 
> >>>non-gnu linker.  It contains the following reloc and symbol table entry:
> >>A little detective work fingers 
> >>http://sourceware.org/ml/binutils/2006-05/msg00458.html
> >
> >It's late here and my brain is about to shut down, but this patch of
> >mine does look suspicious.  I can't think why I decided that
> >ignore_section_sym should test symbol value, except that was what
> >elf_map_symbols was doing before in the first loop I touched.  (There
> >is nothing in the ELF spec that says a section symbol should have zero
> >value.)
> 
> Thanks for the speedy response.  I remove the sym->value != 0 test from 
> ignore_section_sym, and it did fix my problem.  It didn't appear to break 
> any i86-linux testcase either.

I think this is what we want.  elf_map_symbols is supposed to create
an array of sections symbols suitable for use in gas relocs, so we
need to keep the sym->value == 0 test in the loop that tries to use
existing symbols.

	* elf.c (ignore_section_sym): Don't test section sym value here.
	(elf_map_symbols): Instead check zero value here as was done prior
	to 2006-05-26 change.

> I'm not sure how to create a testcase for this though, any suggestions?

Nope..

Index: bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.447
diff -u -p -r1.447 elf.c
--- bfd/elf.c	29 May 2008 07:07:20 -0000	1.447
+++ bfd/elf.c	4 Jun 2008 13:14:22 -0000
@@ -3078,17 +3078,15 @@ sym_is_global (bfd *abfd, asymbol *sym)
 }
 
 /* Don't output section symbols for sections that are not going to be
-   output.  Also, don't output section symbols for reloc and other
-   special sections.  */
+   output.  */
 
 static bfd_boolean
 ignore_section_sym (bfd *abfd, asymbol *sym)
 {
   return ((sym->flags & BSF_SECTION_SYM) != 0
-	  && (sym->value != 0
-	      || (sym->section->owner != abfd
-		  && (sym->section->output_section->owner != abfd
-		      || sym->section->output_offset != 0))));
+	  && !(sym->section->owner == abfd
+	       || (sym->section->output_section->owner == abfd
+		   && sym->section->output_offset == 0)));
 }
 
 static bfd_boolean
@@ -3131,6 +3129,7 @@ elf_map_symbols (bfd *abfd)
       asymbol *sym = syms[idx];
 
       if ((sym->flags & BSF_SECTION_SYM) != 0
+	  && sym->value == 0
 	  && !ignore_section_sym (abfd, sym))
 	{
 	  asection *sec = sym->section;

-- 
Alan Modra
Australia Development Lab, IBM