[Bug c++/14639] [3.5 Regression] [non-unit-at-a-time] Incorrect emission of unused compiler-generated destructor

["hubicka at ucw dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From hubicka at ucw dot cz  2004-06-04 21:16 -------
Subject: Re:  [3.5 Regression] [non-unit-at-a-time] Incorrect emission of unused compiler-generated destructor

> 
> ------- Additional Comments From hubicka at ucw dot cz  2004-06-04 21:11 -------
> Subject: Re:  [3.5 Regression] [non-unit-at-a-time] Incorrect emission of unused compiler-generated destructor
> 
> > 
> > ------- Additional Comments From pinskia at gcc dot gnu dot org  2004-06-04 01:50 -------
> > This should fix it by making non-unit-at-a-time more like unit-at-a-time also removes one ??? to fix 
> > the rest of the way because now we mark the variables when outputing the asm so there is no need to 
> > do it while analyzing the function.  I have not tested or bootstrapped this yet, Robert could you test this 
> > as I have a test to study for/do?
> > 
> > Index: passes.c
> > ===============================================================
> > ====
> > RCS file: /cvs/gcc/gcc/gcc/passes.c,v
> > retrieving revision 2.17
> > diff -u -p -r2.17 passes.c
> > --- passes.c	30 May 2004 18:32:27 -0000	2.17
> > +++ passes.c	4 Jun 2004 01:45:17 -0000
> > @@ -370,7 +370,7 @@ rest_of_decl_compilation (tree decl,
> >  	   || (flag_unit_at_a_time && DECL_INITIAL (decl)))
> >  	  && !DECL_EXTERNAL (decl))
> >  	{
> > -	  if (flag_unit_at_a_time && !cgraph_global_info_ready
> > +	  if (!cgraph_global_info_ready
> >  	      && TREE_CODE (decl) != FUNCTION_DECL && top_level)
> >  	    cgraph_varpool_finalize_decl (decl);
> >  	  else
> > Index: cgraphunit.c
> > ===============================================================
> > ====
> > RCS file: /cvs/gcc/gcc/gcc/cgraphunit.c,v
> > retrieving revision 1.64
> > diff -u -p -r1.64 cgraphunit.c
> > --- cgraphunit.c	30 May 2004 18:32:24 -0000	1.64
> > +++ cgraphunit.c	4 Jun 2004 01:45:17 -0000
> > @@ -395,11 +395,6 @@ record_call_1 (tree *tp, int *walk_subtr
> >    switch (TREE_CODE (t))
> >      {
> >      case VAR_DECL:
> > -      /* ??? Really, we should mark this decl as *potentially* referenced
> > -	 by this function and re-examine whether the decl is actually used
> > -	 after rtl has been generated.  */
> > -      if (TREE_STATIC (t))
> > -        cgraph_varpool_mark_needed_node (cgraph_varpool_node (t));
> 
> The mark call here must stay (it is the only place we do the
> reachability analysis in the case we will drop it here compiler will
> break at least if we get past the callback from the asm outputting code
> (I am currently testing patch to do it but it has problems still...)
> 
> The "needed" in cgraph sense is "conservatively needed" so the Richard
> comment should be probably placed elsewhere as this is defect of
> callgraph code affecting both functions and variables.  The problem is
> that at the moment cgraph code is trusting to "needed" flag for
> variables and output them early instead of later pass really checking
> whether they are really needed (ie still referenced by the optimized
> body of function).  The reason why it is done this way is that I still
> rely on backend calling me back when variable is needed as it is quite
> non-trivial to do the reachability analysis on all kinds of
> datastructures output by the front-end.  I am working on that as we
> speak, but it will take time (I just hit problems with Java and
> objective C bypassing the cgraph as I feared)

OK, while writing the long philophical reply I forgot to ask.  Steven,
did you tracked down what is going wrong?
We might get around by not marking functions as needed in
non-unit-at-a-time but this is also going to break with changes I want
to do, so I would rather preffer to have some better sollution.

Honza
> 
> Honza
> >        break;
> >  
> >      case ADDR_EXPR:
> > 
> > 
> > -- 
> > 
> > 
> > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14639
> > 
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> 
> 
> -- 
> 
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14639
> 
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14639