Re: [gc-improv] Permanent vs function RTL obstack fix

[Basile Starynkevitch <basile@starynkevitch.net>]

On Sun, 10 Apr 2011 21:27:10 +0300
Laurynas Biveinis <laurynas.biveinis@gmail.com> wrote:

> 2011/4/9 Steven Bosscher <stevenb.gcc@gmail.com>:
> > 4. RTL per function. GCC expands one GIMPLE function at a time, and
> > the idea is to initialize the RTL obstack once when expanding starts,
> > let it grow until final, and blow it away after final. Unlike 20 years
> > ago, this obstack is never rolled back during RTL passes. This relies
> > on generating not too much garbage, but memory for per-function RTL
> > should be dwarfed by per-translation unit GIMPLE anyway.
> 
> Well, I have plans to see if it is worthwhile for pass like combine to
> rollback the function obstack to do away with scratch RTL. Of course
> this depends, on how much memory can be saved by doing this - in
> comparison to current GC.


I respect a lot Laurynas' work, but my general personal feeling & wish
is on the contrary that in the long term, more GCC data should be
garbage collected, and that GCC's garbage collector should be better.

However, I tend to believe that Laurynas cleanup on RTL could be
helpful.

And in the long run, I would imagine that making RTL data garbage
collectable again would just be a matter of adding GTY annotations
somewhere.

Regards.
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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