With bounds checking by default, even if a compiler can't statically prove that an index is in bounds, if the index in practice is always in bounds, the compile

With bounds checking by default, even if a compiler can't statically prove that an index is in bounds, if the index in practice is always in bounds, the compiler inlines the check/branch into the calling function, and you're not starved of branch prediction resources, the check will be "free" because the branch will always be predicted as taken.