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Re: On inlining in C++ with unit-at-a-time code
- From: Geoff Keating <geoffk at geoffk dot org>
- To: neroden at twcny dot rr dot com (Nathanael Nerode)
- Cc: gcc at gcc dot gnu dot org
- Date: 07 Aug 2003 13:40:56 -0700
- Subject: Re: On inlining in C++ with unit-at-a-time code
- References: <20030807192344.GA803@twcny.rr.com>
neroden@twcny.rr.com (Nathanael Nerode) writes:
> Jan said:
> >Unforutnately we can't do the change on mainline yet as old inlining
> >heuristics is still active for -O2 and will result in memory bombs
> >then.
> >I hope we can enable unit-at-a-time at -O2 by default and solve the
> >problem in easy way. In SuSE we are experimentally building the
> >distribution with it and now all problems directly attributable to
> >unit-at-a-time seems to be gone. I will send more detailed summary
> >sometime next week as this week I am on the trip. Of course few
> >remaining patches I sent needs to get in first but Mark seems to be
> >doing great job on reviewing them.
>
> I would also like to see unit-at-a-time enabled by default for GCC 3.4.
> Given that it's always a valid way to compile C/C++, I'd like to see
> it enabled at *all* optimization levels (although it makes little
> pratical difference at -O0).
>
> Think this will be possible? :-)
I don't think it would be a good idea at -O0 because of the extra
memory consumption. I'm not sure whether it'd be appropriate at -O1,
I suspect probably not, it's pretty expensive. I'd like to see it on
at -O2 for sure, and maybe -Os.
--
- Geoffrey Keating <geoffk@geoffk.org>