[PATCH] D28508: [NVPTX] Implement NVPTXTargetLowering::getSqrtEstimate.

[escha via Phabricator via llvm-commits]

escha added a comment.

afaik, x * rsqrt(x) is wrong when x is zero (it gives NaN instead of 0). we use x * rsqrt(x) for our expansion, but we have to use an extra select_cc to handle the zero special case.


Repository:
  rL LLVM

https://reviews.llvm.org/D28508