这两句同步语句是否可以合并为


合并为 ` b = _bottom.load(butil::memory_order_seq_cst);`
不知道这里为什么要加两个fence

Locate the synchronization statements shown in the issue and inspect the surrounding code that accesses _bottom. Compare the proposed atomic load with the existing fences under the relevant concurrency assumptions; done means the maintainers have a justified decision about whether the statements can be merged.

Written by the indexing model from the issue text.