runtime.exit looks like this:

TEXT runtime·exit(SB),NOSPLIT,$0
	MOVL	$252, AX	// syscall number
	MOVL	code+0(FP), BX
	INVOKE_SYSCALL
	INT $3	// not reached
	RET

asmfmt writes this as:

TEXT runtime·exit(SB), NOSPLIT, $0
	MOVL           $252, AX       // syscall number
	MOVL           code+0(FP), BX
	INVOKE_SYSCALL
	INT            $3             // not reached
	RET

but I think:

TEXT runtime·exit(SB), NOSPLIT, $0
	MOVL    $252, AX	// syscall number
	MOVL	code+0(FP), BX
	INVOKE_SYSCALL
	INT	$3		// not reached
	RET

is better.