fadd.h instruction operation results are different

[fly-1011]

Before start

• I have read the RISC-V ISA Manual and this is not a RISC-V ISA question. 我已经阅读过 RISC-V 指令集手册，这不是一个指令集本身的问题。
• I have read the XiangShan Documents. 我已经阅读过香山文档。
• I have searched the previous issues and did not find anything relevant. 我已经搜索过之前的 issue，并没有找到相关的。
• I have reviewed the commit messages from the relevant commit history. 我已经浏览过相关的提交历史和提交信息。

Describe the bug

When executing fadd.h fs11, ft0, fs7 instructions (ft0: 0xffffffffffff0000 fs7: 0xffffffffffff828d), the operation results are different.

Expected behavior

Log screenshot

The log information of spike is the same, but the result of Xiangshan is unexpected.

To Reproduce

Initialize ft0: 0xffffffffffff0000
Initialize fs7: 0xffffffffffff828d
Execute fadd.h fs11, ft0, fs7

Environment

• XiangShan branch:
• XiangShan commit id: b00d582 (HEAD -> master, origin/master, origin/HEAD)
• NEMU commit id:
• SPIKE commit id:
  ready-to-run:commit 457f091898b2bcd26c8f6e983f3df174f990af43

Additional context

No response

[Tang-Haojin]

Thank you for your tests. zfh/zvfh actually have not been thoroughly verified so bugs are expected. We will investigate your issue.

[HeiHuDie]

Thanks, this is a known bug and has been fixed, but it has not been merged into master