Vector alignment tracking

Andi Kleen andi@firstfloor.org
Thu Oct 13 17:06:00 GMT 2011


> Or I am missing someting?

I often see the x86 vectorizer with -mtune=generic generate a lot of
complicated code just to adjust for potential misalignment.

My thought was just if the alias oracle knows what the original
declaration is, and it's available for changes (e.g. LTO), it would be 
likely be better to just add an __attribute__((aligned()))
there.

In the general case it's probably harder, you would need some 
cost model to decide when it's worth it.

Your approach of course would still be needed for cases where this
isn't possible. But it sounded like the infrastructure you're building
could in principle do both.

-Andi



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