Underflow flag issue

[HamzaShabbir517]

hello,
We were testing Floating point unit and we encounter one issue that during the operation of fadd and fsub instruction the underflow flag does not get high whereas in fmul,fmadd,fmsub,fnmadd and fnmsub the underflow flag gets high whenever the result is subnormal.

Can you explain what is the logic behind it.

Regards:
Hamza Shabbir