[PATCH] [x86] @llvm.ctpop.v8i32 custom lowering

[Bruno Cardoso Lopes]

> I see you've gone ahead and committed this.

> 

> Please actually implement the significantly better algorithm I point you at

>  if you're going to have an x86-speciifc implementation. Also please

>  implement this for the other vector types. I really don't want this to be

>  left in a half-done state forever.


I understand your concern, I'll get to it, promise :-)

> Expanding to other vector types doesn't seem unreasonable to do in a

>  follow-up patch, but I think it would have been better to start off with

>  the final algorithm. We now have a pretty substantial pile of code in the

>  x86 backend that will be completely replaced. =/


Although you're probably right, I rather not do it before giving it appropriate
measurements which I couldn't get yet. Also, since we already know this performs
better than previous expansions, at least we have better generation for ctpop
in the meantime.

Thanks for the feedback and ideas :D


http://reviews.llvm.org/D6531

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