COMPMID-1137 OpenCL concatenate width

Change-Id: I40faba421281b1cf080fa6a825d04a4366cdaeb0
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/130700
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>

16 files changed, 968 insertions, 1 deletions

diff --git a/arm_compute/core/CL/CLKernels.h b/arm_compute/core/CL/CLKernels.h
index 9316c6e489..f1171a8c10 100644
--- a/arm_compute/core/CL/CLKernels.h
+++ b/arm_compute/core/CL/CLKernels.h
@@ -113,6 +113,7 @@
 #include "arm_compute/core/CL/kernels/CLWarpAffineKernel.h"
 #include "arm_compute/core/CL/kernels/CLWarpPerspectiveKernel.h"
 #include "arm_compute/core/CL/kernels/CLWeightsReshapeKernel.h"
+#include "arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h"
 #include "arm_compute/core/CL/kernels/CLWinogradFilterTransformKernel.h"
 #include "arm_compute/core/CL/kernels/CLWinogradInputTransformKernel.h"
 #include "arm_compute/core/CL/kernels/CLWinogradOutputTransformKernel.h"
diff --git a/arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h b/arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h
new file mode 100644
index 0000000000..5b8a318320
--- /dev/null
+++ b/arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __ARM_COMPUTE_CLWIDTHCONCATENATELAYERKERNEL_H__
+#define __ARM_COMPUTE_CLWIDTHCONCATENATELAYERKERNEL_H__
+
+#include "arm_compute/core/CL/ICLKernel.h"
+#include "arm_compute/core/Types.h"
+
+namespace arm_compute
+{
+class ICLTensor;
+
+/** Interface for the width concatenate kernel.
+ *  The input tensor will be concatenated into the output tensor.
+ */
+class CLWidthConcatenateLayerKernel : public ICLKernel
+{
+public:
+    /** Default constructor */
+    CLWidthConcatenateLayerKernel();
+    /** Prevent instances of this class from being copied (As this class contains pointers) */
+    CLWidthConcatenateLayerKernel(const CLWidthConcatenateLayerKernel &) = delete;
+    /** Prevent instances of this class from being copied (As this class contains pointers) */
+    CLWidthConcatenateLayerKernel &operator=(const CLWidthConcatenateLayerKernel &) = delete;
+    /** Allow instances of this class to be moved */
+    CLWidthConcatenateLayerKernel(CLWidthConcatenateLayerKernel &&) = default;
+    /** Allow instances of this class to be moved */
+    CLWidthConcatenateLayerKernel &operator=(CLWidthConcatenateLayerKernel &&) = default;
+    /** Default destructor */
+    ~CLWidthConcatenateLayerKernel() = default;
+    /** Initialise the kernel's inputs and output
+     *
+     * @param[in]     input        Input tensor. Data types supported: U8/S8/QS8/QASYMM8/U16/S16/QS16/F16/U32/S32/F32
+     * @param[in]     width_offset The offset on the X axis.
+     * @param[in,out] output       Output tensor. Data types supported: Same as @p input.
+     *
+     */
+    void configure(const ICLTensor *input, unsigned int width_offset, ICLTensor *output);
+    /**  Static function to check if given info will lead to a valid configuration of @ref CLDepthConcatenateLayerKernel
+     *
+     * @param[in] input        Input tensor info. Data types supported: U8/S8/QS8/QASYMM8/U16/S16/QS16/F16/U32/S32/F32
+     * @param[in] width_offset The offset on the X axis.
+     * @param[in] output       Output tensor info. Data types supported: Same as @p input.
+     *
+     * @return a status
+     */
+    static Status validate(const ITensorInfo *input, unsigned int width_offset, const ITensorInfo *output);
+
+    // Inherited methods overridden:
+    void run(const Window &window, cl::CommandQueue &queue) override;
+
+private:
+    const ICLTensor *_input;
+    ICLTensor       *_output;
+    unsigned int     _width_offset;
+};
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_CLWIDTHCONCATENATELAYERKERNEL_H__ */
diff --git a/arm_compute/core/utils/misc/ShapeCalculator.h b/arm_compute/core/utils/misc/ShapeCalculator.h
index 30d3f9bb62..deab181aee 100644
--- a/arm_compute/core/utils/misc/ShapeCalculator.h
+++ b/arm_compute/core/utils/misc/ShapeCalculator.h
@@ -366,6 +366,35 @@ inline TensorShape compute_mm_shape(const ITensorInfo &input0, const ITensorInfo
 
     return tensor_shape;
 }
+
+template <typename T>
+inline TensorShape get_shape_from_info(T *info)
+{
+    return info->info()->tensor_shape();
+}
+
+inline TensorShape get_shape_from_info(ITensorInfo *info)
+{
+    return info->tensor_shape();
+}
+
+template <typename T>
+inline TensorShape calculate_width_concatenate_shape(const std::vector<T *> &inputs_vector)
+{
+    TensorShape out_shape = get_shape_from_info(inputs_vector[0]);
+
+    size_t width = 0;
+    for(const auto &tensor : inputs_vector)
+    {
+        ARM_COMPUTE_ERROR_ON(tensor == nullptr);
+        const TensorShape shape = get_shape_from_info(tensor);
+        width += shape.x();
+    }
+
+    out_shape.set(0, width);
+
+    return out_shape;
+}
 } // namespace shape_calculator
 } // namespace misc
 } // namespace arm_compute
diff --git a/arm_compute/runtime/CL/CLFunctions.h b/arm_compute/runtime/CL/CLFunctions.h
index 0d9407bfe4..a01e4a7978 100644
--- a/arm_compute/runtime/CL/CLFunctions.h
+++ b/arm_compute/runtime/CL/CLFunctions.h
@@ -111,6 +111,7 @@
 #include "arm_compute/runtime/CL/functions/CLTranspose.h"
 #include "arm_compute/runtime/CL/functions/CLWarpAffine.h"
 #include "arm_compute/runtime/CL/functions/CLWarpPerspective.h"
+#include "arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h"
 #include "arm_compute/runtime/CL/functions/CLWinogradConvolutionLayer.h"
 #include "arm_compute/runtime/CL/functions/CLWinogradInputTransform.h"
 
diff --git a/arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h b/arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h
new file mode 100644
index 0000000000..bcda05274b
--- /dev/null
+++ b/arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef __ARM_COMPUTE_CLWIDTHCONCATENATELAYER_H__
+#define __ARM_COMPUTE_CLWIDTHCONCATENATELAYER_H__
+
+#include "arm_compute/core/CL/OpenCL.h"
+#include "arm_compute/core/Types.h"
+#include "arm_compute/core/Window.h"
+#include "arm_compute/runtime/IFunction.h"
+
+#include "arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h"
+
+#include <memory>
+#include <vector>
+
+namespace arm_compute
+{
+class ICLTensor;
+
+/** Basic function to execute concatenate tensors along x axis. This function calls the following kernel:
+ *
+ * -# @ref CLDepthConcatenateLayerKernel
+ *
+ */
+class CLWidthConcatenateLayer : public IFunction
+{
+public:
+    /** Default constructor */
+    CLWidthConcatenateLayer();
+    /** Initialise the kernel's inputs vector and output.
+     *
+     * @param[in,out] inputs_vector The vectors containing all the tensors to concatenate. Data types supported: QS8/QASYMM8/QS16/F16/F32.
+     * @param[out]    output        Output tensor. Data types supported: Same as @p input.
+     */
+    void configure(std::vector<ICLTensor *> inputs_vector, ICLTensor *output);
+    /** Static function to check if given info will lead to a valid configuration of @ref CLDepthConcatenateLayerKernel
+     *
+     * @param[in] inputs_vector The vectors containing all the tensors info to concatenate. Data types supported: QS8/QASYMM8/QS16/F16/F32.
+     * @param[in] output        Output tensor info. Data types supported: Same as @p input.
+     *
+     * @return a status
+     */
+    static Status validate(const std::vector<ITensorInfo *> &inputs_vector, const ITensorInfo *output);
+
+    // Inherited methods overridden:
+    void run() override;
+
+private:
+    std::unique_ptr<CLWidthConcatenateLayerKernel[]> _concat_kernels_vector;
+    unsigned int                                     _num_inputs;
+};
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_CLWIDTHCONCATENATELAYER_H__ */
diff --git a/src/core/CL/CLKernelLibrary.cpp b/src/core/CL/CLKernelLibrary.cpp
index 220c7490f3..bdb26f8b0f 100644
--- a/src/core/CL/CLKernelLibrary.cpp
+++ b/src/core/CL/CLKernelLibrary.cpp
@@ -172,6 +172,7 @@ const std::map<std::string, std::string> CLKernelLibrary::_kernel_program_map =
     { "combine_gradients_L1", "canny.cl" },
     { "combine_gradients_L2", "canny.cl" },
     { "concatenate_depth", "concatenate.cl" },
+    { "concatenate_width", "concatenate.cl" },
     { "convolution_rectangle", "convolution_rectangle.cl" },
     { "col2im", "col2im.cl" },
     { "convert_depth_down", "depth_convert.cl" },
diff --git a/src/core/CL/cl_kernels/concatenate.cl b/src/core/CL/cl_kernels/concatenate.cl
index a92ab5bdad..f97ae13a9a 100644
--- a/src/core/CL/cl_kernels/concatenate.cl
+++ b/src/core/CL/cl_kernels/concatenate.cl
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 ARM Limited.
+ * Copyright (c) 2017-2018 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -23,6 +23,41 @@
  */
 #include "helpers.h"
 
+/** This kernel concatenates the input tensor into the output tensor along the first dimension
+ *
+ * @param[in]  src_ptr                           Pointer to the source tensor. Supported data types: QS8, QASYMM8, QS16, F16, F32
+ * @param[in]  src_stride_x                      Stride of the source tensor in X dimension (in bytes)
+ * @param[in]  src_step_x                        src_stride_x * number of elements along X processed per workitem(in bytes)
+ * @param[in]  src_stride_y                      Stride of the source tensor in Y dimension (in bytes)
+ * @param[in]  src_step_y                        src_stride_y * number of elements along Y processed per workitem(in bytes)
+ * @param[in]  src_stride_z                      Stride of the source tensor in Z dimension (in bytes)
+ * @param[in]  src_step_z                        src_stride_z * number of elements along Z processed per workitem(in bytes)
+ * @param[in]  src_offset_first_element_in_bytes The offset of the first element in the source tensor
+ * @param[out] dst_ptr                           Pointer to the destination tensor. Supported data types: same as @p src_ptr
+ * @param[in]  dst_stride_x                      Stride of the destination tensor in X dimension (in bytes)
+ * @param[in]  dst_step_x                        dst_stride_x * number of elements along X processed per workitem(in bytes)
+ * @param[in]  dst_stride_y                      Stride of the destination tensor in Y dimension (in bytes)
+ * @param[in]  dst_step_y                        dst_stride_y * number of elements along Y processed per workitem(in bytes)
+ * @param[in]  dst_stride_z                      Stride of the source tensor in Z dimension (in bytes)
+ * @param[in]  dst_step_z                        dst_stride_z * number of elements along Z processed per workitem(in bytes)
+ * @param[in]  dst_offset_first_element_in_bytes The offset of the first element in the destination tensor
+ * @param[in]  offset                            The offset to the first valid element of the output tensor in bytes
+ */
+__kernel void concatenate_width(
+    TENSOR3D_DECLARATION(src),
+    TENSOR3D_DECLARATION(dst),
+    int offset)
+{
+    Tensor3D src = CONVERT_TO_TENSOR3D_STRUCT(src);
+    Tensor3D dst = CONVERT_TO_TENSOR3D_STRUCT(dst);
+
+    VEC_DATA_TYPE(DATA_TYPE, VEC_SIZE)
+    source_values = VLOAD(VEC_SIZE)(0, (__global DATA_TYPE *)src.ptr);
+
+    VSTORE(VEC_SIZE)
+    (source_values, 0, (__global DATA_TYPE *)(dst.ptr + offset));
+}
+
 /** This kernel concatenates the input tensor into the output tensor along the third dimension
  *
  * @param[in]  src_ptr                           Pointer to the source tensor. Supported data types: QS8, QS16, F16, F32
diff --git a/src/core/CL/kernels/CLWidthConcatenateLayerKernel.cpp b/src/core/CL/kernels/CLWidthConcatenateLayerKernel.cpp
new file mode 100644
index 0000000000..b8bce38cad
--- /dev/null
+++ b/src/core/CL/kernels/CLWidthConcatenateLayerKernel.cpp
@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "arm_compute/core/CL/kernels/CLWidthConcatenateLayerKernel.h"
+
+#include "arm_compute/core/CL/CLHelpers.h"
+#include "arm_compute/core/CL/CLKernelLibrary.h"
+#include "arm_compute/core/CL/ICLTensor.h"
+#include "arm_compute/core/CL/OpenCL.h"
+#include "arm_compute/core/Error.h"
+#include "arm_compute/core/Helpers.h"
+#include "arm_compute/core/IAccessWindow.h"
+#include "arm_compute/core/TensorInfo.h"
+#include "arm_compute/core/Utils.h"
+#include "arm_compute/core/Validate.h"
+#include "arm_compute/core/Window.h"
+#include "arm_compute/core/utils/misc/ShapeCalculator.h"
+
+#include "support/ToolchainSupport.h"
+
+#include <map>
+
+using namespace arm_compute;
+namespace
+{
+std::pair<Status, Window> validate_and_configure_window(ITensorInfo *input, unsigned int width_offset, ITensorInfo *output)
+{
+    const unsigned int num_elems_processed_per_iteration = 16;
+
+    // The window needs to be based on input as we copy all the widths of input
+    Window                 win = calculate_max_window(*input, Steps(num_elems_processed_per_iteration));
+    AccessWindowHorizontal input_access(input, 0, num_elems_processed_per_iteration);
+    AccessWindowHorizontal output_access(output, width_offset, num_elems_processed_per_iteration);
+    bool                   window_changed = update_window_and_padding(win, input_access, output_access);
+
+    Status err = (window_changed) ? ARM_COMPUTE_CREATE_ERROR(ErrorCode::RUNTIME_ERROR, "Insufficient Padding!") : Status{};
+    return std::make_pair(err, win);
+}
+Status validate_arguments(const ITensorInfo *input, unsigned int width_offset, const ITensorInfo *output)
+{
+    ARM_COMPUTE_RETURN_ERROR_ON_NULLPTR(input, output);
+    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(input, 1, DataType::U8, DataType::S8, DataType::QS8, DataType::QASYMM8, DataType::U16, DataType::S16, DataType::QS16, DataType::F16, DataType::U32,
+                                                         DataType::F32);
+    ARM_COMPUTE_RETURN_ERROR_ON_MISMATCHING_DATA_TYPES(input, output);
+    ARM_COMPUTE_RETURN_ERROR_ON_MISMATCHING_FIXED_POINT_POSITION(input, output);
+    ARM_COMPUTE_RETURN_ERROR_ON(input->dimension(0) + width_offset > output->dimension(0));
+
+    for(size_t i = 1; i < Coordinates::num_max_dimensions; ++i)
+    {
+        ARM_COMPUTE_RETURN_ERROR_ON(input->dimension(i) != output->dimension(i));
+    }
+    ARM_COMPUTE_RETURN_ERROR_ON(input->num_dimensions() > 3);
+
+    return Status{};
+}
+} // namespace
+
+CLWidthConcatenateLayerKernel::CLWidthConcatenateLayerKernel()
+    : _input(nullptr), _output(nullptr), _width_offset(0)
+{
+}
+
+Status CLWidthConcatenateLayerKernel::validate(const ITensorInfo *input, unsigned int width_offset, const ITensorInfo *output)
+{
+    ARM_COMPUTE_RETURN_ON_ERROR(validate_arguments(input, width_offset, output));
+    ARM_COMPUTE_RETURN_ON_ERROR(validate_and_configure_window(input->clone().get(), width_offset, output->clone().get()).first);
+    return Status{};
+}
+
+void CLWidthConcatenateLayerKernel::configure(const ICLTensor *input, unsigned int width_offset, ICLTensor *output)
+{
+    ARM_COMPUTE_ERROR_ON_NULLPTR(input, output);
+    ARM_COMPUTE_ERROR_THROW_ON(validate_arguments(input->info(), width_offset, output->info()));
+
+    _input        = input;
+    _output       = output;
+    _width_offset = width_offset;
+
+    const unsigned int num_elems_processed_per_iteration = 16;
+
+    // Add build options
+    CLBuildOptions build_opts;
+    build_opts.add_option("-DDATA_TYPE=" + get_underlying_cl_type_from_data_type(input->info()->data_type()));
+    build_opts.add_option("-DVEC_SIZE=" + support::cpp11::to_string(num_elems_processed_per_iteration));
+
+    // Create kernel
+    _kernel = static_cast<cl::Kernel>(CLKernelLibrary::get().create_kernel("concatenate_width", build_opts.options()));
+
+    const int offset_to_first_elements_in_bytes = _width_offset * _output->info()->strides_in_bytes()[0];
+
+    unsigned int idx = 2 * num_arguments_per_3D_tensor(); // Skip the input and output parameters
+    _kernel.setArg<cl_int>(idx, offset_to_first_elements_in_bytes);
+
+    // Configure kernel window
+    auto win_config = validate_and_configure_window(input->info(), width_offset, output->info());
+    ARM_COMPUTE_ERROR_THROW_ON(std::get<0>(win_config));
+
+    ICLKernel::configure(std::get<1>(win_config));
+}
+
+void CLWidthConcatenateLayerKernel::run(const Window &window, cl::CommandQueue &queue)
+{
+    ARM_COMPUTE_ERROR_ON_UNCONFIGURED_KERNEL(this);
+    ARM_COMPUTE_ERROR_ON_INVALID_SUBWINDOW(ICLKernel::window(), window);
+
+    Window slice = window.first_slice_window_3D();
+
+    do
+    {
+        unsigned int idx = 0;
+        add_3D_tensor_argument(idx, _input, slice);
+        add_3D_tensor_argument(idx, _output, slice);
+        enqueue(queue, *this, slice);
+    }
+    while(window.slide_window_slice_3D(slice));
+}
diff --git a/src/runtime/CL/functions/CLWidthConcatenateLayer.cpp b/src/runtime/CL/functions/CLWidthConcatenateLayer.cpp
new file mode 100644
index 0000000000..d5427819c3
--- /dev/null
+++ b/src/runtime/CL/functions/CLWidthConcatenateLayer.cpp
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h"
+
+#include "arm_compute/core/CL/ICLTensor.h"
+#include "arm_compute/core/Error.h"
+#include "arm_compute/core/Helpers.h"
+#include "arm_compute/core/TensorInfo.h"
+#include "arm_compute/core/Types.h"
+#include "arm_compute/core/utils/misc/ShapeCalculator.h"
+#include "arm_compute/runtime/CL/CLScheduler.h"
+#include "support/ToolchainSupport.h"
+
+using namespace arm_compute;
+
+CLWidthConcatenateLayer::CLWidthConcatenateLayer() // NOLINT
+    : _concat_kernels_vector(),
+      _num_inputs(0)
+{
+}
+
+Status CLWidthConcatenateLayer::validate(const std::vector<ITensorInfo *> &inputs_vector, const ITensorInfo *output) // NOLINT
+{
+    ARM_COMPUTE_RETURN_ERROR_ON_NULLPTR(output);
+    ARM_COMPUTE_RETURN_ERROR_ON(inputs_vector.size() < 2);
+
+    // Output auto inizialitation if not yet initialized
+    TensorInfo  tmp_output_info = *output->clone();
+    TensorShape output_shape    = arm_compute::misc::shape_calculator::calculate_width_concatenate_shape(inputs_vector);
+    auto_init_if_empty(tmp_output_info, output_shape, 1, inputs_vector[0]->data_type(), inputs_vector[0]->fixed_point_position());
+
+    unsigned int width_offset = 0;
+    for(const auto &input : inputs_vector)
+    {
+        ARM_COMPUTE_RETURN_ERROR_ON_NULLPTR(input);
+        ARM_COMPUTE_RETURN_ON_ERROR(CLWidthConcatenateLayerKernel::validate(input, width_offset, &tmp_output_info));
+        width_offset += input->dimension(0);
+    }
+
+    return Status{};
+}
+
+void CLWidthConcatenateLayer::configure(std::vector<ICLTensor *> inputs_vector, ICLTensor *output) // NOLINT
+{
+    _num_inputs = inputs_vector.size();
+
+    std::vector<ITensorInfo *> inputs_vector_info;
+    for(unsigned int i = 0; i < _num_inputs; i++)
+    {
+        inputs_vector_info.emplace_back(inputs_vector.at(i)->info());
+    }
+    TensorShape output_shape = arm_compute::misc::shape_calculator::calculate_width_concatenate_shape(inputs_vector);
+
+    // Output auto inizialitation if not yet initialized
+    auto_init_if_empty(*output->info(), output_shape, 1, inputs_vector[0]->info()->data_type(), inputs_vector[0]->info()->fixed_point_position());
+    ARM_COMPUTE_ERROR_THROW_ON(CLWidthConcatenateLayer::validate(inputs_vector_info, output->info()));
+
+    unsigned int width_offset = 0;
+
+    _concat_kernels_vector = arm_compute::support::cpp14::make_unique<CLWidthConcatenateLayerKernel[]>(_num_inputs);
+
+    for(unsigned int i = 0; i < _num_inputs; i++)
+    {
+        _concat_kernels_vector[i].configure(inputs_vector.at(i), width_offset, output);
+        width_offset += inputs_vector.at(i)->info()->dimension(0);
+    }
+}
+
+void CLWidthConcatenateLayer::run()
+{
+    cl::CommandQueue q = CLScheduler::get().queue();
+
+    for(unsigned i = 0; i < _num_inputs; i++)
+    {
+        CLScheduler::get().enqueue(_concat_kernels_vector[i], true);
+    }
+}
diff --git a/tests/datasets/ShapeDatasets.h b/tests/datasets/ShapeDatasets.h
index 76cf9a1835..b138a425b9 100644
--- a/tests/datasets/ShapeDatasets.h
+++ b/tests/datasets/ShapeDatasets.h
@@ -523,6 +523,21 @@ public:
     }
 };
 
+/** Data set containing tensor shapes for WidthConcatenateLayer. */
+class WidthConcatenateLayerShapes final : public ShapeDataset
+{
+public:
+    WidthConcatenateLayerShapes()
+        : ShapeDataset("Shape",
+    {
+        TensorShape{ 232U, 65U, 3U },
+                     TensorShape{ 432U, 65U, 3U },
+                     TensorShape{ 124U, 65U, 3U }
+    })
+    {
+    }
+};
+
 /** Data set containing global pooling tensor shapes. */
 class GlobalPoolingShapes final : public ShapeDataset
 {
diff --git a/tests/validation/CL/WidthConcatenateLayer.cpp b/tests/validation/CL/WidthConcatenateLayer.cpp
new file mode 100644
index 0000000000..0ff95df957
--- /dev/null
+++ b/tests/validation/CL/WidthConcatenateLayer.cpp
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "arm_compute/core/Types.h"
+#include "arm_compute/runtime/CL/CLTensor.h"
+#include "arm_compute/runtime/CL/CLTensorAllocator.h"
+#include "arm_compute/runtime/CL/functions/CLWidthConcatenateLayer.h"
+#include "tests/CL/CLAccessor.h"
+#include "tests/datasets/ShapeDatasets.h"
+#include "tests/framework/Asserts.h"
+#include "tests/framework/Macros.h"
+#include "tests/framework/datasets/Datasets.h"
+#include "tests/validation/Validation.h"
+#include "tests/validation/fixtures/WidthConcatenateLayerFixture.h"
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+TEST_SUITE(CL)
+TEST_SUITE(WidthConcatenateLayer)
+// *INDENT-OFF*
+// clang-format off
+DATA_TEST_CASE(Validate, framework::DatasetMode::ALL, zip(zip(zip(
+              framework::dataset::make("InputInfo1", {  TensorInfo(TensorShape(23U, 27U, 5U), 1, DataType::F32, 0), // Mismatching data type input/output
+                                                        TensorInfo(TensorShape(23U, 27U, 5U), 1, DataType::F32, 0), // Mismatching y dimension
+                                                        TensorInfo(TensorShape(23U, 27U, 5U), 1, DataType::F32, 0), // Mismatching total width
+                                                        TensorInfo(TensorShape(16U, 27U, 5U), 1, DataType::F32, 0)
+              }),
+              framework::dataset::make("InputInfo2", {  TensorInfo(TensorShape(24U, 27U, 4U), 1, DataType::F32, 0),
+                                                        TensorInfo(TensorShape(52U, 27U, 5U), 1, DataType::F32, 0),
+                                                        TensorInfo(TensorShape(52U, 27U, 5U), 1, DataType::F32, 0),
+                                                        TensorInfo(TensorShape(16U, 27U, 5U), 1, DataType::F32, 0)
+              })),
+              framework::dataset::make("OutputInfo", {  TensorInfo(TensorShape(47U, 27U, 5U), 1, DataType::F16, 0),
+                                                        TensorInfo(TensorShape(75U, 12U, 5U), 1, DataType::F32, 0),
+                                                        TensorInfo(TensorShape(11U, 27U, 5U), 1, DataType::F32, 0),
+                                                        TensorInfo(TensorShape(32U, 27U, 5U), 1, DataType::F32, 0)
+              })),
+              framework::dataset::make("Expected", { false, false, false, true })),
+              input_info1, input_info2, output_info,expected)
+{
+    std::vector<TensorInfo> inputs_vector_info;
+    inputs_vector_info.emplace_back(std::move(input_info1));
+    inputs_vector_info.emplace_back(std::move(input_info2));
+
+    std::vector<ITensorInfo *> inputs_vector_info_raw;
+    for(auto &input : inputs_vector_info)
+    {
+        inputs_vector_info_raw.emplace_back(&input);
+    }
+
+    bool is_valid = bool(CLWidthConcatenateLayer::validate(inputs_vector_info_raw,
+                                                           &output_info.clone()->set_is_resizable(false)));
+    ARM_COMPUTE_EXPECT(is_valid == expected, framework::LogLevel::ERRORS);
+}
+// clang-format on
+// *INDENT-ON*
+
+TEST_CASE(Configuration, framework::DatasetMode::ALL)
+{
+    // Create tensors
+    CLTensor src1 = create_tensor<CLTensor>(TensorShape(128U, 32U, 32U), DataType::F32, 1);
+    CLTensor src2 = create_tensor<CLTensor>(TensorShape(32U, 32U, 32U), DataType::F32, 1);
+    CLTensor src3 = create_tensor<CLTensor>(TensorShape(15U, 32U, 32U), DataType::F32, 1);
+    CLTensor dst;
+
+    ARM_COMPUTE_EXPECT(src1.info()->is_resizable(), framework::LogLevel::ERRORS);
+    ARM_COMPUTE_EXPECT(src2.info()->is_resizable(), framework::LogLevel::ERRORS);
+    ARM_COMPUTE_EXPECT(src3.info()->is_resizable(), framework::LogLevel::ERRORS);
+    ARM_COMPUTE_EXPECT(dst.info()->is_resizable(), framework::LogLevel::ERRORS);
+
+    // Create and configure function
+    CLWidthConcatenateLayer concat_layer;
+
+    concat_layer.configure({ &src1, &src2, &src3 }, &dst);
+}
+
+template <typename T>
+using CLWidthConcatenateLayerFixture = WidthConcatenateLayerValidationFixture<CLTensor, ICLTensor, CLAccessor, CLWidthConcatenateLayer, T>;
+
+TEST_SUITE(Float)
+TEST_SUITE(FP16)
+FIXTURE_DATA_TEST_CASE(RunSmall, CLWidthConcatenateLayerFixture<half>, framework::DatasetMode::PRECOMMIT, combine(datasets::Small2DShapes(), framework::dataset::make("DataType",
+                                                                                                                  DataType::F16)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+FIXTURE_DATA_TEST_CASE(RunLarge, CLWidthConcatenateLayerFixture<half>, framework::DatasetMode::NIGHTLY, combine(datasets::Large2DShapes(), framework::dataset::make("DataType",
+                                                                                                                DataType::F16)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+TEST_SUITE_END()
+
+TEST_SUITE(FP32)
+FIXTURE_DATA_TEST_CASE(RunSmall, CLWidthConcatenateLayerFixture<float>, framework::DatasetMode::PRECOMMIT, combine(datasets::Small2DShapes(), framework::dataset::make("DataType",
+                                                                                                                   DataType::F32)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+FIXTURE_DATA_TEST_CASE(RunLarge, CLWidthConcatenateLayerFixture<float>, framework::DatasetMode::NIGHTLY, combine(datasets::WidthConcatenateLayerShapes(), framework::dataset::make("DataType",
+                                                                                                                 DataType::F32)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+TEST_SUITE_END()
+TEST_SUITE_END()
+
+TEST_SUITE(Quantized)
+TEST_SUITE(QS8)
+FIXTURE_DATA_TEST_CASE(RunTiny, CLWidthConcatenateLayerFixture<int8_t>, framework::DatasetMode::PRECOMMIT, combine(datasets::Tiny2DShapes(),
+                                                                                                                   framework::dataset::make("DataType",
+                                                                                                                           DataType::QS8)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+FIXTURE_DATA_TEST_CASE(RunSmall, CLWidthConcatenateLayerFixture<int8_t>, framework::DatasetMode::NIGHTLY, combine(datasets::WidthConcatenateLayerShapes(),
+                                                                                                                  framework::dataset::make("DataType",
+                                                                                                                          DataType::QS8)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+TEST_SUITE_END()
+
+TEST_SUITE(QS16)
+FIXTURE_DATA_TEST_CASE(RunTiny, CLWidthConcatenateLayerFixture<int16_t>, framework::DatasetMode::PRECOMMIT, combine(datasets::Tiny2DShapes(),
+                                                                                                                    framework::dataset::make("DataType",
+                                                                                                                            DataType::QS16)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+FIXTURE_DATA_TEST_CASE(RunSmall, CLWidthConcatenateLayerFixture<int16_t>, framework::DatasetMode::NIGHTLY, combine(datasets::WidthConcatenateLayerShapes(),
+                                                                                                                   framework::dataset::make("DataType",
+                                                                                                                           DataType::QS16)))
+{
+    // Validate output
+    validate(CLAccessor(_target), _reference);
+}
+TEST_SUITE_END()
+TEST_SUITE_END()
+
+TEST_SUITE_END()
+TEST_SUITE_END()
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
diff --git a/tests/validation/Helpers.cpp b/tests/validation/Helpers.cpp
index 0707c6a247..25dc6c568d 100644
--- a/tests/validation/Helpers.cpp
+++ b/tests/validation/Helpers.cpp
@@ -98,6 +98,21 @@ TensorShape calculate_depth_concatenate_shape(const std::vector<TensorShape> &in
     return out_shape;
 }
 
+TensorShape calculate_width_concatenate_shape(const std::vector<TensorShape> &input_shapes)
+{
+    ARM_COMPUTE_ERROR_ON(input_shapes.empty());
+
+    TensorShape out_shape = input_shapes[0];
+
+    int width = std::accumulate(input_shapes.begin(), input_shapes.end(), 0, [](int sum, const TensorShape & shape)
+    {
+        return sum + shape.x();
+    });
+    out_shape.set(0, width);
+
+    return out_shape;
+}
+
 HarrisCornersParameters harris_corners_parameters()
 {
     HarrisCornersParameters params;
diff --git a/tests/validation/Helpers.h b/tests/validation/Helpers.h
index b5597090c6..d07803fb94 100644
--- a/tests/validation/Helpers.h
+++ b/tests/validation/Helpers.h
@@ -148,6 +148,14 @@ void fill_mask_from_pattern(uint8_t *mask, int cols, int rows, MatrixPattern pat
  */
 TensorShape calculate_depth_concatenate_shape(const std::vector<TensorShape> &input_shapes);
 
+/** Calculate output tensor shape give a vector of input tensor to concatenate
+ *
+ * @param[in] input_shapes Shapes of the tensors to concatenate across width.
+ *
+ * @return The shape of output concatenated tensor.
+ */
+TensorShape calculate_width_concatenate_shape(const std::vector<TensorShape> &input_shapes);
+
 /** Parameters of Harris Corners algorithm. */
 struct HarrisCornersParameters
 {
diff --git a/tests/validation/fixtures/WidthConcatenateLayerFixture.h b/tests/validation/fixtures/WidthConcatenateLayerFixture.h
new file mode 100644
index 0000000000..cf9b12eab6
--- /dev/null
+++ b/tests/validation/fixtures/WidthConcatenateLayerFixture.h
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_FIXTURE
+#define ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_FIXTURE
+
+#include "arm_compute/core/TensorShape.h"
+#include "arm_compute/core/Types.h"
+#include "arm_compute/core/utils/misc/ShapeCalculator.h"
+#include "tests/AssetsLibrary.h"
+#include "tests/Globals.h"
+#include "tests/IAccessor.h"
+#include "tests/framework/Asserts.h"
+#include "tests/framework/Fixture.h"
+#include "tests/validation/Helpers.h"
+#include "tests/validation/reference/WidthConcatenateLayer.h"
+
+#include <random>
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+template <typename TensorType, typename ITensorType, typename AccessorType, typename FunctionType, typename T>
+class WidthConcatenateLayerValidationFixture : public framework::Fixture
+{
+public:
+    template <typename...>
+    void setup(TensorShape shape, DataType data_type)
+    {
+        // Create input shapes
+        std::mt19937                    gen(library->seed());
+        std::uniform_int_distribution<> num_dis(2, 4);
+        const int                       num_tensors = num_dis(gen);
+
+        std::vector<TensorShape>         shapes(num_tensors, shape);
+        std::bernoulli_distribution      mutate_dis(0.5f);
+        std::uniform_real_distribution<> change_dis(-0.25f, 0.f);
+
+        // Generate more shapes based on the input
+        for(auto &s : shapes)
+        {
+            // Randomly change the first dimension
+            if(mutate_dis(gen))
+            {
+                // Decrease the dimension by a small percentage. Don't increase
+                // as that could make tensor too large.
+                s.set(0, s[0] + 2 * static_cast<int>(s[0] * change_dis(gen)));
+            }
+        }
+
+        _target    = compute_target(shapes, data_type);
+        _reference = compute_reference(shapes, data_type);
+    }
+
+protected:
+    template <typename U>
+    void fill(U &&tensor, int i)
+    {
+        library->fill_tensor_uniform(tensor, i);
+    }
+
+    TensorType compute_target(std::vector<TensorShape> shapes, DataType data_type)
+    {
+        std::vector<TensorType>    srcs;
+        std::vector<ITensorType *> src_ptrs;
+
+        // Create tensors
+        srcs.reserve(shapes.size());
+
+        for(const auto &shape : shapes)
+        {
+            srcs.emplace_back(create_tensor<TensorType>(shape, data_type, 1, _fractional_bits));
+            src_ptrs.emplace_back(&srcs.back());
+        }
+
+        TensorShape dst_shape = misc::shape_calculator::calculate_width_concatenate_shape(src_ptrs);
+        TensorType  dst       = create_tensor<TensorType>(dst_shape, data_type, 1, _fractional_bits);
+
+        // Create and configure function
+        FunctionType width_concat;
+        width_concat.configure(src_ptrs, &dst);
+
+        for(auto &src : srcs)
+        {
+            ARM_COMPUTE_EXPECT(src.info()->is_resizable(), framework::LogLevel::ERRORS);
+        }
+
+        ARM_COMPUTE_EXPECT(dst.info()->is_resizable(), framework::LogLevel::ERRORS);
+
+        // Allocate tensors
+        for(auto &src : srcs)
+        {
+            src.allocator()->allocate();
+            ARM_COMPUTE_EXPECT(!src.info()->is_resizable(), framework::LogLevel::ERRORS);
+        }
+
+        dst.allocator()->allocate();
+        ARM_COMPUTE_EXPECT(!dst.info()->is_resizable(), framework::LogLevel::ERRORS);
+
+        // Fill tensors
+        int i = 0;
+        for(auto &src : srcs)
+        {
+            fill(AccessorType(src), i++);
+        }
+
+        // Compute function
+        width_concat.run();
+
+        return dst;
+    }
+
+    SimpleTensor<T> compute_reference(std::vector<TensorShape> shapes, DataType data_type)
+    {
+        std::vector<SimpleTensor<T>> srcs;
+
+        // Create and fill tensors
+        int i = 0;
+        for(const auto &shape : shapes)
+        {
+            srcs.emplace_back(shape, data_type, 1, _fractional_bits);
+            fill(srcs.back(), i++);
+        }
+
+        return reference::widthconcatenate_layer<T>(srcs);
+    }
+
+    TensorType      _target{};
+    SimpleTensor<T> _reference{};
+
+private:
+    int _fractional_bits{ 1 };
+};
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
+#endif /* ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_FIXTURE */
diff --git a/tests/validation/reference/WidthConcatenateLayer.cpp b/tests/validation/reference/WidthConcatenateLayer.cpp
new file mode 100644
index 0000000000..fe79b4a138
--- /dev/null
+++ b/tests/validation/reference/WidthConcatenateLayer.cpp
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "WidthConcatenateLayer.h"
+
+#include "tests/validation/FixedPoint.h"
+#include "tests/validation/Helpers.h"
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+template <typename T>
+SimpleTensor<T> widthconcatenate_layer(const std::vector<SimpleTensor<T>> &srcs)
+{
+    // Create reference
+    std::vector<TensorShape> shapes;
+
+    for(const auto &src : srcs)
+    {
+        shapes.emplace_back(src.shape());
+    }
+
+    DataType        dst_type  = srcs.empty() ? DataType::UNKNOWN : srcs[0].data_type();
+    TensorShape     dst_shape = calculate_width_concatenate_shape(shapes);
+    SimpleTensor<T> dst(dst_shape, dst_type);
+
+    // Compute reference
+    int       width_offset = 0;
+    const int width_out    = dst.shape().x();
+
+    // Set output tensor to 0
+    std::fill_n(dst.data(), dst.num_elements(), 0);
+
+    for(const auto &src : srcs)
+    {
+        ARM_COMPUTE_ERROR_ON(width_offset >= width_out);
+
+        const int width  = src.shape().x();
+        const int height = src.shape().y();
+        const int depth  = src.shape().z();
+
+        const T *src_ptr = src.data();
+        T       *dst_ptr = dst.data();
+
+        for(int d = 0; d < depth; ++d)
+        {
+            for(int r = 0; r < height; ++r)
+            {
+                int offset = d * height + r;
+                std::copy(src_ptr, src_ptr + width, dst_ptr + width_offset + offset * width_out);
+                src_ptr += width;
+            }
+        }
+
+        width_offset += width;
+    }
+
+    return dst;
+}
+
+template SimpleTensor<float> widthconcatenate_layer(const std::vector<SimpleTensor<float>> &srcs);
+template SimpleTensor<half> widthconcatenate_layer(const std::vector<SimpleTensor<half>> &srcs);
+template SimpleTensor<qint8_t> widthconcatenate_layer(const std::vector<SimpleTensor<qint8_t>> &srcs);
+template SimpleTensor<qint16_t> widthconcatenate_layer(const std::vector<SimpleTensor<qint16_t>> &srcs);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
diff --git a/tests/validation/reference/WidthConcatenateLayer.h b/tests/validation/reference/WidthConcatenateLayer.h
new file mode 100644
index 0000000000..237e72b947
--- /dev/null
+++ b/tests/validation/reference/WidthConcatenateLayer.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef __ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_H__
+#define __ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_H__
+
+#include "tests/SimpleTensor.h"
+
+#include <vector>
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+template <typename T>
+SimpleTensor<T> widthconcatenate_layer(const std::vector<SimpleTensor<T>> &srcs);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute
+#endif /* __ARM_COMPUTE_TEST_WIDTHCONCATENATE_LAYER_H__ */