the sources of the standard library, in packages such as
<a href="/pkg/runtime/"><code>runtime</code></a> and
<a href="/pkg/math/big/"><code>math/big</code></a>.
You can also examine what the compiler emits as assembly code:
</p>

<pre>
$ cat x.go
package main

func main() {
	println(3)
}
$ go tool 6g -S x.go        # or: go build -gcflags -S x.go

--- prog list "main" ---
0000 (x.go:3) TEXT    main+0(SB),$8-0
0001 (x.go:3) FUNCDATA $0,gcargs·0+0(SB)
0002 (x.go:3) FUNCDATA $1,gclocals·0+0(SB)
0003 (x.go:4