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Re: [PATCH] Simplify FRE parts of PRE, try to save some memory
On Tue, 4 Sep 2012, Steven Bosscher wrote:
> On Tue, Sep 4, 2012 at 3:19 PM, Richard Guenther <rguenther@suse.de> wrote:
> >
> > Currently computa_avail consumes an unreasonable amount of memory
> > in the FRE case for PR46590. The following patch makes some
> > obvious adjustments but does not cure the underlying issue.
>
> I don't think there's any way to cure the underlying issue, it's just
> the result of having SSA form that so many values are available. You
> can improve the representation of the sets (e.g. something similar to
> the views of the tree-ssa-live machinery) but that's it.
One idea is that we only need AVAIL for the block we are currently
doing elimination on (well, for FRE - PRE is another story). And
we need AVAIL only for values we are going to replace. The first
can be exploited by a domwalk unifying elimination and AVAIL
computation for FRE, the 2nd one is harder ;) At least sounds like
a reason to finally split FRE from PRE ...
Richard.