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Re: [tree-ssa PATCH] Pick memory consumption low hanging fruit
- From: law at redhat dot com
- To: Andrew MacLeod <amacleod at redhat dot com>
- Cc: Steven Bosscher <s dot bosscher at student dot tudelft dot nl>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 19 Nov 2003 08:44:23 -0700
- Subject: Re: [tree-ssa PATCH] Pick memory consumption low hanging fruit
- Reply-to: law at redhat dot com
In message <1069209358.30711.663.camel@p4>, Andrew MacLeod writes:
>On Tue, 2003-11-18 at 18:40, email@example.com wrote:
>> In message <1069194489.30703.332.camel@p4>, Andrew MacLeod writes:
>> >Thats overall. If we collected between passes, or free'd SSAisms, or
>> >something along those lines, it wouldn't be as bad from function to
>> >function. Sure we'd have a highwater mark, but it wouldnt push the
>> >envelope as much. Is there a reason we dont collect bewteen functions?
>> >we know both SSA and RTL aren't going to carry over fom one function to
>> >the next. (Don't we?? :-)
>> Err, what do you mean we don't collect between functions? I'm pretty sure
>> we do collect between functions. Hell, at the RTL level, we collect betwee
>> optimization passes :-)
>> Now, we may have some problems with templates and such since I think
>> they are considered "nested" functions. I've got a message from Steven
>> regarding that issue that I'll need to look at carefully.
>I ASSUME since I only see the [..->..} message rarely that it occurs
>whenever we GC.
Yes. But also remember that we only GC when the heuristics think it's
worth the trouble. If you've got a lot of memory in your machine and you
do not have checking enabled, then we'll go a lot longer before the GC
system does anything.
>It seems like a different beast to me. I hate to say it but there were
>certain characterisitics about obstacks that were good in general
>intent... probably what spawned them in the first place. It was more the
>implmementation and actual usage that were bad. Dont get me wrong, they
>drove me nuts. For slightly, but important, different reasons than we're
>talking about here.
Most definitely they had certain characteristics that were helpful and
others which were insanely bad. The hell of it is we had a "one or
the other" kind of system -- we don't have a scheme which allows us to
mix-n-match based on the characteristics of the objects we are allocating.