This example is taken from Golang’s math package in its standard library. The function has been implemented in different assembly languages in order to leverage different architecture’s hardware support for the square root function. 

package math


func Sqrt(x float64) float64

The Go compiler will look for files ending in 

∕∕ sqrt_386.s


#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
FMOVD x+0(FP),F0
FSQRT
FMOVDP F0,ret+8(FP)
RET

∕∕ sqrt_amd64.s


#include "textflag.h"


TEXT ·Sqrt(SB), NOSPLIT, $0
XORPS X0, X0 // break dependency
SQRTSD x+0(FP), X0
MOVSD X0, ret+8(FP)
RET

amd64p32 is the native client (Nacl) amd64 instruction set with a 32bit address space, 32bit pointers and 32bit type ints and uints. It is a sandbox architecture used for example in play.golang.org 
∕∕ `sqrt_amd64p32.s`

As the amd64 assembly file is fine, we’ll use that. 
#include "sqrt_amd64.s"

∕∕ sqrt_arm.s


#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
MOVD x+0(FP),F0
SQRTD F0,F0
MOVD F0,ret+8(FP)
RET

∕∕ sqrt_arm64.s


#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
FMOVD x+0(FP), F0
FSQRTD F0, F0
FMOVD F0, ret+8(FP)
RET

∕∕ sqrt_mipsx.s


This file’s name doesn’t match any 
∕∕ +build mips mipsle

#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
MOVD x+0(FP), F0
SQRTD F0, F0
MOVD F0, ret+8(FP)
RET

∕∕ sqrt_ppc64x.s


∕∕ +build ppc64 ppc64le
#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
FMOVD x+0(FP), F0
FSQRT F0, F0
FMOVD F0, ret+8(FP)
RET

∕∕ sqart_s389x.s


#include "textflag.h"


TEXT ·Sqrt(SB),NOSPLIT,$0
FMOVD x+0(FP), F1
FSQRT F1, F1
FMOVD F1, ret+8(FP)
RET
