The following code does not treat volatile struct members as volatile,
assuming such declarations are valid; if not would exect a warning:

typedef struct {
  volatile int a;
  volatile int b;
  } s;

int main (void){

  s x = {0, 1};
  s y = {2, 3};
  
  x = y;
  y = x;
  
  return x.a + y.a;

}

generates:

000000c6 <main>:
  volatile int a;
  volatile int b;
  } s;

int main (void){
  c6:	cf ef       	ldi	r28, 0xFF	; 255
  c8:	d0 e1       	ldi	r29, 0x10	; 16
  ca:	de bf       	out	0x3e, r29	; 62
  cc:	cd bf       	out	0x3d, r28	; 61

  s x = {0, 1};
  s y = {2, 3};
  
  x = y;
  y = x;
  
  return x.a + y.a;

}
  ce:	84 e0       	ldi	r24, 0x04	; 4
  d0:	90 e0       	ldi	r25, 0x00	; 0
  d2:	0c 94 6b 00 	jmp	0xd6 <_exit>