By default, Rust will perform level 3 optimizations in the code. Optimizations get divided into levels depending on how complex they are. Higher-level optimizations, in theory, improve the performance of the code greatly, but they might have bugs that could change the behavior of the program. Usually, level 1 optimizations are totally safe, and level 2 optimizations are the most-used ones in the C/C++ ecosystem. Level 3 optimizations have not been known to cause any issues, but in some critical situations, it might be better to avoid them. This can be configured, but we should first understand how the Rust compiler compiles the code to machine instructions so that we know what different options accomplish.
Rust first starts ...
