VEX_X
if ((VEX_X & evex_byte1) == 0) {
if ((evex_byte1 & VEX_X) == 0)
vex_byte1 = (opcode3 & VEX_R) | VEX_X | VEX_B;
vex_X = (opcode3 & VEX_X) >> 2;
vex_byte1 = opcode3 & (VEX_R | VEX_X | VEX_B);