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Re: cache misses in gcc 3.3
- From: law at redhat dot com
- To: Diego Novillo <dnovillo at redhat dot com>
- Cc: Andi Kleen <ak at muc dot de>, gcc at gcc dot gnu dot org
- Date: Mon, 10 Feb 2003 10:53:17 -0700
- Subject: Re: cache misses in gcc 3.3
- Reply-to: law at redhat dot com
In message <20030210173107.GA24303@tornado.toronto.redhat.com>, Diego Novillo w
rites:
>On Mon, 10 Feb 2003, Andi Kleen wrote:
>
>> GCSE doesn't seem to be that slow, just CSE is.
>>
>Finger trouble. I didn't mean to insert that extra 'G'. Force
>of habit.
Well, it's worth mentioning that there are aspects of GCSE which I expect
to be largely subsumed by the SSA work as well.
For example, null pointer check removal can be completely subsumed by
the tree-ssa code. That code is a known memory and cpu hog (that's why
Mark brought in the blocking code in the past). What will be *very*
interesting will be to see what value gcse/lcm has once we've got the
tree-ssa optimizer going.
While I expect there'll always be some constants or expressions that
only gcse will catch (specifically those created by the lowering process),
I expect that we can drop the memory tracking bits from gcse and maybe
simplify other stuff (like constant/copy propagation).
jeff