[RFC PATCH] Don't use ELF weak for entities with vague linkage whenCOMDAT groups are available

[Julian Brown <julian at codesourcery dot com>]

Hi,

This is a patch to disable ELF weak for entities with vague linkage when 
HAVE_GAS_COMDAT_GROUP is true. It was previously posted in two parts and 
applied, then reverted soon after for causing breakage:

elfos.h patch:
  http://gcc.gnu.org/ml/gcc-patches/2005-02/msg01624.html

Java patch:
  http://gcc.gnu.org/ml/gcc-patches/2005-03/msg00712.html

These patches caused two problems. The first was causing bootstrap 
failure on Darwin/ppc:

  http://gcc.gnu.org/ml/gcc-regression/2005-03/msg00060.html

And the other was causing lots of "size of symbol changed" regressions:

  http://gcc.gnu.org/ml/gcc-regression/2005-03/msg00056.html

I believe I have fixed the former problem with the attached patch, but I 
have been unable to reproduce the latter test failures. I have tried on 
various machines, including:

  i686-pc-linux-gnu, Red Hat 8.0, bundled binutils (2.16.90) (no COMDAT 
group support).

  i686-pc-linux-gnu, Red Hat 8.0, binutils from cvs (2.16.90 20050330) 
(with COMDAT support).

  powerpc-apple-darwin7.4.0, cctools-576 (no COMDAT support)

  i686-pc-linux-gnu, Debian testing, bundled binutils (2.15) (no COMDAT 
support)

I haven't seen any sign of "size of symbol changed"-type errors after 
running tests on any of these machines. They may have been indicative of 
a system which has COMDAT support in the assembler, but not the linker, 
for some reason.

If people would try this patch and run the testsuite on their machines, 
I'd be grateful. I'd appreciate it if you post information about 
failures which show up for you, with version numbers of binutils bits, 
so I can attempt to track down whatever broke before.

Thanks,

Julian
Index: gcc/config/elfos.h
===================================================================
RCS file: /home/gcc/repos/gcc/gcc/gcc/config/elfos.h,v
retrieving revision 1.70
diff -c -p -r1.70 elfos.h
*** gcc/config/elfos.h	8 Mar 2005 23:24:46 -0000	1.70
--- gcc/config/elfos.h	31 Mar 2005 16:19:16 -0000
*************** Boston, MA 02111-1307, USA.  */
*** 212,218 ****
    fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
  #endif
  
! #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
  
  /* Switch into a generic section.  */
  #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
--- 212,226 ----
    fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
  #endif
  
! /* Don't use weak for entities with vague linkage when HAVE_GAS_COMDAT_GROUP
!    is true.  */
! #define MAKE_DECL_ONE_ONLY(DECL)			\
!   do							\
!     {							\
!       if (!HAVE_GAS_COMDAT_GROUP)			\
! 	DECL_WEAK(DECL) = 1;				\
!     }							\
!   while (0)
  
  /* Switch into a generic section.  */
  #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
Index: gcc/java/decl.c
===================================================================
RCS file: /home/gcc/repos/gcc/gcc/gcc/java/decl.c,v
retrieving revision 1.214
diff -c -p -r1.214 decl.c
*** gcc/java/decl.c	23 Mar 2005 20:26:58 -0000	1.214
--- gcc/java/decl.c	4 Apr 2005 20:19:34 -0000
*************** finish_method (tree fndecl)
*** 2052,2057 ****
--- 2052,2064 ----
  		    build2 (TRY_FINALLY_EXPR, void_type_node, *tp, exit));
      }
  
+   /* Ensure non-abstract non-static non-private members are defined only once
+      when linking. This is an issue when using CNI to interface with C++ object
+      files.  */
+   if (! METHOD_STATIC (fndecl) && ! METHOD_PRIVATE (fndecl)
+       && ! METHOD_ABSTRACT (fndecl) && ! METHOD_FINAL (fndecl))
+     make_decl_one_only (fndecl);
+ 
    /* Prepend class initialization for static methods reachable from
       other classes.  */
    if (METHOD_STATIC (fndecl)