https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105246
--- Comment #2 from Andrew Stubbs <ams at gcc dot gnu.org> --- When we first coded this we only had the GCN3 ISA manual, which says nothing about the accuracy. Now I look in the Vega manual (GCN5) I see: Square root with perhaps not the accuracy you were hoping for -- (2**29)ULP accuracy. On the upside, denormals are supported. The most recent CDNA2 manual is a bit less verbose: Square root. Precision is (2**29) ULP, and supports denormals. The compiler already emits Newton Raphson iterations for division with -ffast-math, so I'm sure it can be done, but I'm not too clear on the mathematics myself.
