Unnecessary fsqrt of 0.0

[Kmeakin]

https://godbolt.org/z/s4T3dc6ae

pub fn sqrt_of_sum(xs: &[f64]) -> f64 {
    xs.iter().sum::<f64>().sqrt()
}

example::sqrt_of_sum::h8605ab463220c776:
        cbz     x1, .LBB0_3
        cmp     x1, #4
        b.hs    .LBB0_4
        mov     x9, #-9223372036854775808
        mov     x8, xzr
        fmov    d0, x9
        b       .LBB0_7
.LBB0_3:
        mov     x8, #-9223372036854775808
        fmov    d0, x8
        fsqrt   d0, d0
        ret
...

The main loop body is not important here, we are concerned with the early return in the len == 0 case. Here, we load 0.0 into x8 and fsqrt it; but we could just return 0.0 directly.