LLVM error when using opt-level 3 with half precision: __gnu_h2f_ieee

Questions
1

I ran into the following error when run ResNet-18 using opt-level 3 with float16.

“LLVM ERROR: Program used external function ‘__gnu_h2f_ieee’ which could not be resolved!”

Note that opt-level 3 with float32 works fine, and opt-level 1 with float16 also works fine.

Anyone knows how to fix this error?

Thanks
Long