The previous implementation incorrectly used instructions for 32-bit
data, this CL fixes it to implement 64-bit operations.

Change-Id: Ib8e5236ea35f3a2c0e37e647ea89aad6a1127425
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1928501
Auto-Submit: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65123}