[PATCH] Improve sqrt estimate algorithm

[hfinkel at anl.gov]

> 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.

Yes, please file a PR and we'll look at it; thanks!

http://reviews.llvm.org/D5682