COMPMID-1277 - Optimizing CLIm2ColKernel for NHWC.

This patch includes:

- Im2Col optimizations for NHWC using a new data layout
- Refactoring of CLIm2ColKernel adding validation method and auto-init
- Removed im2col_reduced from CLIm2ColKernel and created a new kernel CLFlattenLayerKernel

Change-Id: I1620640b6796baa268324b33ae92cdd8de53e27c
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/141241
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Giorgio Arena <giorgio.arena@arm.com>
diff --git a/src/core/CL/cl_kernels/convolution_layer.cl b/src/core/CL/cl_kernels/convolution_layer.cl
index 9335b04..2b75b45 100644
--- a/src/core/CL/cl_kernels/convolution_layer.cl
+++ b/src/core/CL/cl_kernels/convolution_layer.cl
@@ -53,7 +53,7 @@
  * @param[in]  total_filters                      Total number of filters. 4th dimension of the weights matrix
  * @param[in]  dst_stride_z                       Stride of the destination tensor in Z dimension (in bytes)
  */
-__kernel void reshape_to_columns_nchw(
+__kernel void reshape_to_columns(
     TENSOR3D_DECLARATION(src),
     IMAGE_DECLARATION(dst),
 #ifdef HAS_BIAS
@@ -109,74 +109,4 @@
         }
     }
 }
-
-/** This kernel reshapes the tensor's low three dimensions to single column
- *
- * @note Datatype should be given as a preprocessor argument using -DDATA_TYPE=type. e.g. -DDATA_TYPE=short
- *
- * @param[in]  src_ptr                            Pointer to the source tensor. Supported data types: 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 Y 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. 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_offset_first_element_in_bytes  The offset of the first element in the destination tensor
- * @param[in]  bias_ptr                           Pointer to the bias tensor. Same as @p src_ptr
- * @param[in]  bias_stride_x                      Stride of the bias tensor in X dimension (in bytes)
- * @param[in]  bias_step_x                        bias_stride_x * number of elements along X processed per workitem(in bytes)
- * @param[in]  bias_offset_first_element_in_bytes The offset of the first element in the source tensor
- * @param[in]  depth                              The depth of the input tensor
- * @param[in]  width                              The width of the input tensor
- * @param[in]  height                             The height of the input tensor
- * @param[in]  total_filters                      Total number of filters. 4th dimension of the weights matrix
- */
-__kernel void reshape_to_columns_nhwc(
-    TENSOR3D_DECLARATION(src),
-    IMAGE_DECLARATION(dst),
-#ifdef HAS_BIAS
-    VECTOR_DECLARATION(bias),
-#endif /* HAS_BIAS */
-    uint depth, uint width, uint height, uint total_filters, uint dst_stride_z)
-{
-    Tensor3D src            = CONVERT_TO_TENSOR3D_STRUCT(src);
-    bool     is_last_thread = (get_global_id(0) == (get_global_size(0) - 1) && get_global_id(1) == (get_global_size(1) - 1) && get_global_id(2) == (get_global_size(2) - 1));
-
-    __global uchar *tmp_src_ptr = src.ptr;
-    __global uchar *tmp_dst_ptr = dst_ptr + dst_offset_first_element_in_bytes + get_global_id(1) * dst_stride_y + get_global_id(2) * width * dst_stride_y + get_global_id(
-                                      0) * width * height * dst_stride_y;
-#ifdef HAS_BIAS
-    __global uchar *tmp_bias_ptr = bias_ptr + bias_offset_first_element_in_bytes;
-#endif /* HAS_BIAS */
-
-    if(is_last_thread)
-    {
-        for(uint i = 0; i < total_filters; ++i)
-        {
-            *((__global DATA_TYPE *)tmp_dst_ptr) = *((__global DATA_TYPE *)tmp_src_ptr);
-
-#ifdef HAS_BIAS
-            *((__global DATA_TYPE *)(tmp_dst_ptr + dst_stride_y)) = *((__global DATA_TYPE *)(tmp_bias_ptr));
-            tmp_bias_ptr += bias_stride_x;
-#endif /* HAS_BIAS */
-            tmp_src_ptr += height * src_stride_z;
-            tmp_dst_ptr += dst_stride_x;
-        }
-    }
-    else
-    {
-        for(uint i = 0; i < total_filters; ++i)
-        {
-            *((__global DATA_TYPE *)tmp_dst_ptr) = *((__global DATA_TYPE *)tmp_src_ptr);
-            tmp_src_ptr += height * src_stride_z;
-            tmp_dst_ptr += dst_stride_x;
-        }
-    }
-}
-#endif // defined(DATA_TYPE) && defined(NUM_GROUPS)
\ No newline at end of file
+#endif // defined(DATA_TYPE)