A hardware divider is usually much faster than a software one. However, there is no proper way to let the div routine decide in runtime.

1. A register of ARM shows whether hardware dividers are integrated. And this register is only accessible in PL1, while normal linux programs run in PL0.
   2.A PL0 program can read /proc/cpuinfo for "idiva idivt" flags, but a div routine should not involve a file operation.

There is no proper way to let the div routine decide in runtime. Unless the user specifies it explicitly.

It is easy enough to check /proc/cpuinfo once on startup and cache the result.

Check /proc/cpuinfo for "idiva" flag on startup might be a way, how are the core developers' opinion?

Checking on startup sounds good to me.

I would vote for call getauxval() / AT_HWCAP at startup.

I have implemented this feature.
https://go-review.googlesource.com/#/c/37496/

A rough test shows the performance improves 40-50%.

For a rough test case

**package main

import "fmt"
import "math/rand"
import "time"

func main() {
var c, g int
var a [70000000]uint32
var b [70000000]uint32
var d [70000000]uint32

r := rand.New(rand.NewSource(time.Now().UnixNano()))

for c = 0; c < cap(b); c++ {
	a[c] = uint32(r.Intn(0x7ffffff0))
	b[c] = uint32(r.Intn(0x3ffffff0))
}

for g = 0; g < 10; g++ {
	k := time.Now()
	for c = 0; c < cap(b); c++ {
		d[c] = a[c] / b[c]
	}
	w := time.Now()
	fmt.Println(w.Sub(k))
}

}**

The hardware divider outputs
5.4371964s
4.209324055s
4.205575531s
4.205909284s
4.205245892s
4.218614714s
4.210164271s
4.205585791s
4.205325164s
4.207941386s

And the software divider outputs
8.238922377s
5.943205893s
5.911372837s
5.914151872s
5.909159482s
5.933686273s
5.909419953s
5.90930063s
5.913579159s
5.909221097s

CL https://golang.org/cl/37496 mentions this issue.

How do we proceed in CL 37496? Keep the simulated DIV/DIVU/MOD/MODU, or remove them?

In patch set 14 of CL 37496,

1. rebased to the newest master branch
2. keep old DIV/DIVU/MOD/MODU while add DIVHW/DIVUHW

Any conclusion for this issue? Whether keep simulated div/mod or not?