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Re: Compilation performance comparison of 3.5.0 and TreeSSA trees on MICO sources as requested in: [tree-ssa] Merge status 2004-05-03
- From: law at redhat dot com
- To: Diego Novillo <dnovillo at redhat dot com>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, Karel Gardas <kgardas at objectsecurity dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Mon, 17 May 2004 13:10:16 -0600
- Subject: Re: Compilation performance comparison of 3.5.0 and TreeSSA trees on MICO sources as requested in: [tree-ssa] Merge status 2004-05-03
- Reply-to: law at redhat dot com
In message <1083800290.3350.6.camel@localhost.localdomain>, Diego Novillo write
s:
>On Wed, 2004-05-05 at 19:33, Jan Hubicka wrote:
>
>> You need ssa form form DCE. Going in/out just for DCE might be bit
>> expensive...
>>
>Well, is it? You probably don't even need the full out-of-ssa pass. If
>at -O0 we only schedule passes the will never create overlapping LRs,
>you can just drop the SSA_NAMEs on the way out.
Right. And DCE certainly doesn't create overlapping lifetimes.
You know, we could actually make the "may create overlapping lifetime" a
property of the optimization passes. That way we just check the property
at out-of-ssa time, if the property is clear, then we just drop the SSA_NAMES.
jeff