Rustの最適化の強力さ

output.asm

example::sum:
        xor     eax, eax
        cmp     edi, 2
        jl      .LBB0_2
        lea     eax, [rdi - 2]
        lea     ecx, [rdi - 3]
        imul    rcx, rax
        shr     rcx
        lea     eax, [rcx + 2*rdi]
        add     eax, -3
.LBB0_2:
        ret

sum.rs

pub fn sum(n: i32) -> i32 {
    (1..n).fold(0, |sum, item| sum + item)
}