[PATCH] [AArch64] Enhance rematerialization by adding a new API isAsCheapAsAMove in TargetInstroInfo

[Eric Christopher]

Hi Quentin, Jiangning,

I'm not sure about this patch (though I love the results!) -

It looks like we're just conflating isRematerializable and
isAsCheapAsAMove, especially in the somewhat random addition of
isRematerializable to some of the instructions and then adding the
rest to isAsCheapAsAMove (and are they universally cheap or is it
really subtarget dependent here?) and I haven't really seen an answer
to Quentin's question about that? Are these actually rematerializable
or is it just cheaper/etc?

Thanks!

-eric

http://reviews.llvm.org/D4361