ReLU6 layer ocl support

include relu6 ocl kernel and layer fusion support

Signed-off-by: Li Peng <peng.li@intel.com>

modules/dnn/src/layers/elementwise_layers.cpp

@@ -381,8 +381,30 @@ struct ReLU6Functor
 #ifdef HAVE_OPENCL
     bool applyOCL(InputArrayOfArrays inps, OutputArrayOfArrays outs, OutputArrayOfArrays internals)
     {
-        // TODO: implement OCL version
-        return false;
+        std::vector<UMat> inputs;
+        std::vector<UMat> outputs;
+
+        inps.getUMatVector(inputs);
+        outs.getUMatVector(outputs);
+        String buildopt = oclGetTMacro(inputs[0]);
+
+        for (size_t i = 0; i < inputs.size(); i++)
+        {
+            UMat& src = inputs[i];
+            UMat& dst = outputs[i];
+
+            ocl::Kernel kernel("ReLU6Forward", ocl::dnn::activations_oclsrc, buildopt);
+            kernel.set(0, (int)src.total());
+            kernel.set(1, ocl::KernelArg::PtrReadOnly(src));
+            kernel.set(2, ocl::KernelArg::PtrWriteOnly(dst));
+            kernel.set(3, (float)minValue);
+            kernel.set(4, (float)maxValue);
+
+            size_t gSize = src.total();
+            CV_Assert(kernel.run(1, &gSize, NULL, false));
+        }
+
+        return true;
     }
 #endif
 
@@ -867,6 +889,9 @@ Ptr<ReLU6Layer> ReLU6Layer::create(const LayerParams& params)
     float maxValue = params.get<float>("max_value", 6.0f);
     Ptr<ReLU6Layer> l(new ElementWiseLayer<ReLU6Functor>(ReLU6Functor(minValue, maxValue)));
     l->setParamsFrom(params);
+    l->minValue = minValue;
+    l->maxValue = maxValue;
+
     return l;
 }