[BUG] Incorrect Result from 'fdiv' Operation Leading to Negative Infinity Instead of Smallest Negative Number

[youzi27]

Is there an existing CVA6 bug for this?

• I have searched the existing bug issues

Bug Description

When performing floating-point division using the fdiv.d instruction in CVA6, under specific conditions where the expected result is the smallest representable negative double-precision floating-point number (0xffefffffffffffff), CVA6 incorrectly returns negative infinity (0xfff0000000000000).

Steps to Reproduce:

1. Load fa7 with 0xc024000000000000.
2. Load fs3 with 0x00000000000002cc.
3. Execute the instruction: fdiv.d ft6, fa7, fs3.
4. Observe the resulting value in ft6.

The log is as follows::

core   0: 0x00000000800052b2 (0x233987d3) fsgnj.d fa5, fs3, fs3
1 0x00000000800052b2 (0x233987d3) f15 0x00000000000002cc
core   0: 0x00000000800052b6 (0x23188853) fsgnj.d fa6, fa7, fa7
1 0x00000000800052b6 (0x23188853) f16 0xc024000000000000
core   0: 0x00000000800052ba (0x1b38f353) fdiv.d  ft6, fa7, fs3
1 0x00000000800052ba (0x1b38f353) f 6 0xfff0000000000000

[JeanRochCoulon]

This Github issue can also be reported on cvfpu side, thanks

[youzi27]

Thanks for the suggestion! I'll report this issue on the cvfpu side as well.