Besides, fix a error in GetMemOp.

Port commit 247b33e9

Change-Id: I34cf0d22870f438fb6bfcd67ef50ec254fb92608
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3869758
Auto-Submit: Liu Yu <liuyu@loongson.cn>
Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Cr-Commit-Position: refs/heads/main@{#82928}