[PATCH] Improve sqrt estimate algorithm

[Sanjay Patel]

Thanks, Hal!

One other comment I'd like to point out here regarding the PPC codegen: I was expecting an 'fsel' to be generated rather than a compare and branch. I won't be able to look into why that happens anytime soon, but I can file a bug if you think that's appropriate. 

X86 codegen (once we enable that) is not going to generate a compare for any of these testcases from what I can tell.

http://reviews.llvm.org/D5682