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


On Thu, May 24, 2012 at 12:12 AM, Richard Guenther <rguenther@suse.de> wrote:
> 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 ...)
>

I opened:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53472


-- 
H.J.


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