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Re: Prune BLOCK_VARs lists in free_lang_data


On January 16, 2016 11:27:09 AM GMT+01:00, Jan Hubicka <hubicka@ucw.cz> wrote:
>> On Fri, 15 Jan 2016, Jan Hubicka wrote:
>> 
>> > Hi,
>> > this is last of my patches to improve partitionability of programs.
>
>> > This patch compacts BLOCK_VARs lists and trows away TYPE_DECLs for
>-g0
>> > and redundant TYPE_DECLs on all levels. It does make noticeable
>difference
>> > on firefox, but I managed to erase the numbers (can re-test them if
>requested)
>> > 
>> > Bootstrapped/regtested x86_64-linux, OK?
>> 
>> Hmm.  So I wonder why remove_unused_locals does not do this then
>> or if it does not because it would change code-gen based on -g/-g0
>> I wonder why your patch wouldn't introduce that issue with LTO.
>
>Usually the things stay to make DECL_UID stable across -g and -g0. 

Only DECL_UID order needs to be stable I think.

>This is not
>the case with LTO,

I don't see how LTO does behave differently here.

 so ATM we do not have same codegen with lto and
>-g/-g0.  I
>guess it is something we can start shooting for once early debug is in.
>> 
>> That said - improve remove_unused_locals instead please?
>
>Yep, that makes sense (though i am not sure every BLOCK_VARs seen by
>lto
>streamer is also seen by this function).  Will update the patch and
>re-measure
>the effect.
>
>Honza



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