[go-nuts] What explains this 6x slowdown ?

['Isaac Gouy' via golang-nuts]

(
Yeah, it's a tiny tiny program from someone's language comparison 
<http://www.hildstrom.com/projects/langcomp/index.html#:~:text=Results%20Table%20%20%20%20%20%20,%20%20225.9%20%2016%20more%20rows%20>
 
but this is a hugely bigger slowdown than gcc or java?

The code change is compile time constant —
    array_length int = 100000000    

— changed to run time value —
    array_length int = 1000000 * iterations 
)


package main
import "os"
import "fmt"
import "strconv"
func main() {
    var (
       element, iteration, iterations, innerloop int
       sum float64
    )

    if len(os.Args) > 1 {
        iterations,_ = strconv.Atoi(os.Args[1])
    }
    fmt.Printf("iterations %d\n", iterations)
    
    var (
        array_length int = 100000000    
        array []float64 = make([]float64, array_length)
    )    
    
    for element = 0; element < array_length; element++ {
        array[element] = float64(element)
    }
    for iteration = 0; iteration < iterations; iteration++ {
        for innerloop = 0; innerloop < 1000000000; innerloop++ {
            sum += array[(iteration + innerloop) % array_length]
        }
    }
    fmt.Printf("sum %E\n", sum)
    array = nil
}

$ /opt/src/go1.16/go/bin/go build -o out test.go
$ time ./out 100
iterations 100
sum 5.000000E+18

real    3m3.225s

====

package main
import "os"
import "fmt"
import "strconv"
func main() {
    var (
       element, iteration, iterations, innerloop int
       sum float64
    )

    if len(os.Args) > 1 {
        iterations,_ = strconv.Atoi(os.Args[1])
    }
    fmt.Printf("iterations %d\n", iterations)
    
    var (
        array_length int = 1000000 * iterations    
        array []float64 = make([]float64, array_length)
    )    
    
    for element = 0; element < array_length; element++ {
        array[element] = float64(element)
    }
    for iteration = 0; iteration < iterations; iteration++ {
        for innerloop = 0; innerloop < 1000000000; innerloop++ {
            sum += array[(iteration + innerloop) % array_length]
        }
    }
    fmt.Printf("sum %E\n", sum)
    array = nil
}

$ /opt/src/go1.16/go/bin/go build -o out test.go
$ time ./out 100
iterations 100
sum 5.000000E+18

real    18m20.737s

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