[BUG] Division Operations made an error in calculating -1/1

[WEIhabi]

Is there an existing CVA6 bug for div?

• I have searched the existing bug issues

Bug Description

Hi, when we performing correctness checks on the division ISA using a formal tool, we discovered that in the serdiv module, when encountering the case of -1/1, the answer is incorrectly computed as 0 instead of the expected correct value of -1.

We have also investigated this issue on the original master of CVA6 and found that someone has already proposed a solution and made improvements to address this problem. You can refer to:
openhwgroup#421

The following is a comparison between the error results obtained from checking the DUV using JasperGold FPV and the golden answer we wrote for SVA.