This program provide simple hack to optimised slice return. When you return slice it will escape to heap but this program contains simple hack to avoid slice escape to heap.

heap-optmised-slice-return.go

package main

import (
	"unsafe"
)

func main() {
	heapOptimised()
	normal()

}

func heapOptimised() string {
	ba := returnBytes()
	ptr := unsafe.Pointer(&ba)
	return *(*string)(ptr)
}

func normal() string {
	ba := returnBytes()
	return string(ba)
}

func returnBytes() []byte {
	str := "roshan"
	ptr := unsafe.Pointer(&str)
	return *(*[]byte)(ptr)
}

Benchmark without use of return value
Benchmark_normal-4      200000000    7.17 ns/op  0 B/op    0 alloc/op
Benchmark_heapOptimised-4      2000000000   0.72 ns/op  0 B/op    0 alloc/op

Benchmark when allocating return value in global variable
Benchmark_heapOptimised-4    30000000     36.0 ns/op   16 B/op    1 alloc/op
Benchmark_normal-4      20000000     56.9 ns/op   24 B/op    2 alloc/op