Re: [PATCH] Use vague linkage for Java methods

[Ranjit Mathew <rmathew at gmail dot com>]

Hi Julian,

  I'm not a Java maintainer, but please CC java-patches@gcc.gnu.org
on all Java patches.

Java has its own ChangeLog under "gcc/java" and therefore
the ChangeLog entry must be just for "decl.c".

The braces ("{}") seem stylistically redundant to me.

Lastly, please do verify Java patches against the Jacks
testsuite as well:

  http://gcc.gnu.org/install/test.html#TOC2

[That link to Jacks is outdated BTW - you can find Jacks
as the "jacks" CVS module within Mauve
(http://sources.redhat.com/mauve/).]

Thanks,
Ranjit.

Julian Brown wrote:
> Hi,
> 
> This patch causes Java methods to be output with once-only ("vague") 
> linkage (so long as they are non-abstract, non-private and non-static, 
> which seem like the right conditions, but I'd be prepared to believe 
> aren't perfect). This helps when using CNI to interface with C++, 
> especially on platforms with COMDAT groups.
> 
> It allows my previous patch to work again:
> 
> http://gcc.gnu.org/ml/gcc-patches/2005-02/msg01624.html
> 
> The problem was that gcjh-produced header files sometimes output full 
> methods in simple cases, which are then put into COMDAT groups by the 
> C++ front-end. Java methods are currently output with weak linkage due 
> to the definition of MAKE_DECL_ONE_ONLY, so this works, apparently 
> somewhat accidentally.
> 
> If MAKE_DECL_ONE_ONLY is altered to not use weak linkage, multiple 
> definitions occur when mixing Java with CNI code.
> 
> This patch has been tested independently (with c,c++,java) on 
> i686-pc-linux-gnu.
> 
> ChangeLog:
> 
>      * gcc/java/decl.c (finish_method): Give methods once-only linkage.
> 
> 
> ------------------------------------------------------------------------
> 
> Index: gcc/java/decl.c
> ===================================================================
> RCS file: /home/gcc/repos/gcc/gcc/gcc/java/decl.c,v
> retrieving revision 1.209
> diff -c -p -r1.209 decl.c
> *** gcc/java/decl.c	14 Feb 2005 14:58:22 -0000	1.209
> --- gcc/java/decl.c	6 Mar 2005 23:55:51 -0000
> *************** finish_method (tree fndecl)
> *** 2036,2041 ****
> --- 2036,2050 ----
>   		    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))
> +     {
> +       make_decl_one_only (fndecl);
> +     }
> + 
>     /* Prepend class initialization for static methods reachable from
>        other classes.  */
>     if (METHOD_STATIC (fndecl) && ! METHOD_PRIVATE (fndecl)


-- 
Ranjit Mathew      Email: rmathew AT gmail DOT com

Bangalore, INDIA.    Web: http://ranjitmathew.hostingzero.com/