opt-level
This flag lets you control the optimization level.
0: no optimizations
1: basic optimizations
2: some optimizations
3: all optimizations
s: optimize for binary size
z: optimize for binary size, but also turn off loop vectorization.
如果我使用Cargo及其--release选项进行构建，将使用哪个优化级别？
cargo build --release
Finished release [optimized] target(s) in 0.75s