Hi,
In pytorch 1.5 it is necessary to enable to profile guided optimization to visualize the fusion group. Thus
torch._C._jit_set_profiling_executor(False)
@torch.jit.script                                                                                                                                                                     
def simple_kernel(x1, y1, x2, y2):                                                                                                                                                    
    xi = torch.max(x1, x2)                                                                                                                                                            
    yi = torch.max(y1, y2)                                                                                                                                                            
    zi = xi+yi                                                                                                                                                                        
    return zi                                                                                                                                                                                                                                                                                                                                                               

zz = simple_kernel(x1, y1, x2, y2)
print(simple_kernel.graph_for(x1,y1,x2,y2))

Will give the optimal answer