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

[Sanjay Patel via llvm-commits]

spatel added a comment.

In http://reviews.llvm.org/D19391#409039, @escha wrote:

> Our target has a legal FABS (it is in fact, free, as it's a modifier). But it's implemented as FADD DST, SRC.ABS, -0.0, which may modify bits other than the top bit.


Ok, I've misunderstood the definition of 'legal' then. I thought that using FADD in place of FABS would be considered "Custom" rather than "Legal". This means we need a new target hook. Any ideas about what that hook would look like?


http://reviews.llvm.org/D19391