[RFC] Improve Tree-SSA if-conversion - convergence of efforts

Michael Matz matz@suse.de
Tue Jul 31 15:06:00 GMT 2007


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).


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