Re: [PATCH][4/n] referenced-vars TLC

[Richard Guenther <rguenther at suse dot de>]

On Wed, 23 May 2012, H.J. Lu wrote:

> On Wed, May 23, 2012 at 5:00 AM, Richard Guenther <rguenther@suse.de> wrote:
> >
> > This finally switches us to not record global vars in referenced-vars.
> > For this to work I had to re-engineer how we handle global var removal
> > from local-decls in remove_unused_locals. ?Incidentially that code
> > already had some sort of a bitmap (for some weird reason even), thus
> > I borrowed that and simplified the handling. ?You may notice that
> > it would be easy to handle all vars that way ...
> >
> > So eventually 5/n will make referenced-vars go away completely
> > (the only serious user seems to be the SSA renamer for its
> > SYMS_TO_RENAME bitmap).
> >
> > Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
> >
> > Richard.
> >
> > 2012-05-23 ?Richard Guenther ?<rguenther@suse.de>
> >
> > ? ? ? ?* tree-dfa.c (add_referenced_var_1): Do not add global vars.
> > ? ? ? ?* tree-ssa-live.c (mark_all_vars_used_1): Handle global vars
> > ? ? ? ?via the global_unused_vars bitmap.
> > ? ? ? ?(remove_unused_locals): Handle global vars in local-decls via
> > ? ? ? ?a global_unused_vars bitmap instead of the used flag in the
> > ? ? ? ?var annotation. ?Simplify global variable handling and removal.
> >
> 
> This breaks bootstrap on Linux/x86-64:
> 
> http://gcc.gnu.org/ml/gcc-regression/2012-05/msg00468.html
> 
> Comparing stages 2 and 3
> warning: gcc/cc1plus-checksum.o differs
> warning: gcc/cc1obj-checksum.o differs
> warning: gcc/cc1-checksum.o differs
> Bootstrap comparison failure!
> gcc/trans-mem.o differs
> gcc/gimple-low.o differs
> gcc/sese.o differs
> make[5]: *** [compare] Error 1
> 
> Please make sure that your compiler used for bootstrap
> doesn't add anything to .comment section, which will
> disable debug compare.

Well, I can't.  Why is debug compare so fragile?  Now trying to find
a way to reproduce (I can't see why it should cause this ...)

Richard.