On 5/15/23 07:54, 钟居哲 wrote:
I don't know why we should not add frm vfsqrt.v since I saw topper (LLVM
maintainer) said we should
not add frm into vsqrt.v. Maybe kito knows the reason ?
I'm pretty sure this is referring to the estimator. The documentation
is very clear that the sqrt estimator is independent of the rounding mode.
While it's not as explicit in the RV manual, a real sqrt instruction
must round to be usable in an IEEE compliant way. If it didn't honor
rounding modes we would largely be unable to use the [v]fsqrt instructions.
Jeff
