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Re: [patch, rfc] Make store motion use alias oracle
- From: "Daniel Berlin" <dberlin at dberlin dot org>
- To: "Zdenek Dvorak" <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 29 Jan 2007 08:56:52 -0500
- Subject: Re: [patch, rfc] Make store motion use alias oracle
- References: <20070129105655.GA2968@atrey.karlin.mff.cuni.cz>
On 1/29/07, Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz> wrote:
Hello,
I have some doubts about its usefulness, though. The usage of alias
oracle makes sm more expensive -- for each "nice" memory reference that
would previously be refused because of may-alias according to vops, we
now need to check all the memory references with that it might conflict
using the alias oracle;
Well, actually, you can do significantly better than this by using
schemes that enable you to only have to check a small subset of the
memory references (those with a base that could alias, those with the
same type if it's dereferenced, etc).
That said, i agree that more experimentation is necessary before we go
ahead with this.