[PATCH] D19391: transform masking off of an FP sign bit into a fabs...but only if it's legal!

[escha via llvm-commits]

escha added a comment.

As far as I know -- "Custom" means something is not legal, but has a custom lowering. It has nothing to do with how it's implemented on the target; it just means that the target has a custom legalization hook (as opposed to Expand or such, which means it doesn't have any custom hook).

We keep FABS legal until the end (much like AMDGPU or similar) -- it's emitted either by folding a modifier onto an existing instruction, or if there's no way to do that, by emitting a "no-op" add. But this happens in Select().


http://reviews.llvm.org/D19391