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Re: GVN-PRE sucks -- well, for SPECCFP2000 mgrid anyway


    > 1) let pre be pre and have the register allocator "rematerialize" the 
    > guys that have been pulled out of the loop.

    I've always tried to argue this approach, but it never seems to get 
    places with people, because it means the register allocator doing *a lot*.

Not necessarly.  After all, reload has "rematerialized" constants almost
since day one and has also rematerialized some addition operations more
recently.  It's not conceptually difficult to add some more things to
rematerialize.  The problem, of course, is that reload is a mess and adding
*anything* to it will be non-trivial.

But I still agree with Kenny that it's the best approach: I don't think
that complex interactions between passes to estimate register pressure
will work well.


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