What is the causing the discrepancies in rounding error between different machines?

Question

Consider the following code

func main() {
    var (
        negativeTwoThirds = -2.0 / 3.0
        negativeSix       = -6.0
        negativeThree     = -3.0
    )

    for _, v := range []float64{negativeTwoThirds} {
        four := negativeSix * v // 4 = (-6.0) * (-2/3)

        print1(negativeThree + four)
        print2(negativeThree, four)
    }
}

func print1(c float64) {
    fmt.Printf("%f (%b)\n", c, math.Float64bits(c))
}

func print2(a, b float64) {
    c := a + b
    fmt.Printf("%f (%b)\n", c, math.Float64bits(c))
}

I tried the code on a personal linux machine as well as on go playground (demo) and it produced both times the output I was expecting

1.000000 (11111111110000000000000000000000000000000000000000000000000000)
1.000000 (11111111110000000000000000000000000000000000000000000000000000)

I tried the code on two macos machines and I got, both times, a rounding error

1.000000 (11111111101111111111111111111111111111111111111111111111111110)
1.000000 (11111111110000000000000000000000000000000000000000000000000000)

Can you help me make sense of the discrepancies

• between print1 and print2?
• between different OS / architecture / go executables?

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Note

• I can only trigger the discrepancy in a for loop
• I've used go version 1.20.x
• Both macbook used for test use the Apple M1 chip (ARM instruction set) and the linux machine has a 11th Gen Intel® Core™ i7-1165G7 (x86 instruction set)

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EDIT: I reported the issue at https://github.com/golang/go/issues/61061