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List:       gcc-patches
Subject:    Re: [RFC] Improve Tree-SSA if-conversion - convergence of efforts
From:       Michael Matz <matz () suse ! de>
Date:       2007-07-31 15:05:53
Message-ID: Pine.LNX.4.64.0707311701480.23011 () wotan ! suse ! de
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Hi,

On Tue, 31 Jul 2007, Daniel Berlin wrote:

> > 2. Store-sinking/load hoisting may have an overhead and may degrade
> > performance unless the relevant conditional branch gets if-converted.
> 
> I agree with you for conditional stores/loads.
> 
> The unconditional store/load stuff, however, is exactly what 
> tree-ssa-sink was meant to do, and belongs there (this is #3 above). I'm 
> certainly going to fight tooth and nail against trying to shoehorn 
> unconditional store sinking into if-conv.

FWIW I also agree that handling unconditional stores/loads does not belong 
in if-conv (or phi-opt), but in ssa-sink (or some similar transformation 
which can or can not use value numbers and the like).


Ciao,
Michael.
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