Why conv+complex elewise doesn't fuse ?

[usstq]

'
x1=conv(x0)
x2=x1 * (x1+3)
'
ZhnagYi 发现 clDNN plugin能够把 x1*(x1+3)这样的计算fuse到conv中，而mkldnn则不能， WHY？

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Following script reproduce the issue, you can see the fuse will fail , check the "cnn_exec_graph.xml" with netron.app

from openvino.inference_engine import IECore
import ngraph as ng
import numpy as np
import os

def run_cnn(func, input:dict):
    ie_network = ng.function_to_cnn(func)
    ie = IECore()
    device = "CPU"
    ie.set_config({"PERF_COUNT":"YES"}, device)
    executable_network = ie.load_network(ie_network, device)
    output = executable_network.infer(input)
    ei = executable_network.get_exec_graph_info()
    ei.serialize("cnn_exec_graph.xml")
    return output


def test_elewise2():
    input_shape = [10,5,32,32]
    input_shape2 = [1,7,1,1]
    x = ng.parameter(shape=input_shape, dtype=np.float32, name="x")
    x2 = ng.parameter(shape=input_shape2, dtype=np.float32, name="x2")
    conv_w = ng.constant(np.random.rand(7,5,3,3), dtype=np.float32, name="conv_w")

    padding_begin = padding_end = [0, 0]
    strides = [1, 1]
    dilations = [1, 1]
    conv_node = ng.convolution(x, conv_w, strides, padding_begin, padding_end, dilations)

    c1 = ng.constant(3, dtype=np.float32, name="c1")
    c2 = ng.constant(np.random.rand(*input_shape2), dtype=np.float32, name="c2")

    add3 = ng.add(conv_node, c1)
    z = ng.multiply(conv_node, c2)   # fuse will not happen if we change c2 into x2 

    f = ng.Function(z, [x, x2], "TestFunction")

    np.random.seed(42)
    data_x = np.random.rand(*input_shape).astype(np.float32)
    data_x2 = np.random.rand(*input_shape2).astype(np.float32)
    result = run_cnn(f, {'x': data_x, 'x2': data_x2})


test_elewise2()

Also if we change c2'shape into (1,7,30,30), it can not be fused.

[usstq]

clDNN code generator outputs OpenCL C-style source code which is much powerful language than Xbak jit used in MKLDNN, so it can fuse much more cases than MKLDNN can