Update Neon™ depthwise kernel

- Reduce duplication and simplify overall structure.
- Improve multi-threaded performance by sharing more data
  in lower-level caches.

Partially Resolves: COMPMID-5054
Signed-off-by: Ramy Elgammal <ramy.elgammal@arm.com>
Change-Id: Iac747f39b21c540122fa75218762631c4d787911
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/7449
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Andrew Mundy
Reviewed-by: Sheri Zhang <sheri.zhang@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/NEON/kernels/arm_conv/depthwise/depthwise_strategies_common.cpp b/src/core/NEON/kernels/arm_conv/depthwise/depthwise_strategies_common.cpp
new file mode 100644
index 0000000..33f2177
--- /dev/null
+++ b/src/core/NEON/kernels/arm_conv/depthwise/depthwise_strategies_common.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2022 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 "depthwise_strategies_common.hpp"
+
+namespace arm_conv {
+namespace depthwise {
+
+unsigned int DepthfirstStrategyUntyped::get_input_rows() const
+{
+  return this->get_kernel_rows() + (this->get_output_rows() - 1) * this->get_stride_rows();
+}
+
+unsigned int DepthfirstStrategyUntyped::get_input_cols() const
+{
+  return this->get_kernel_cols() + (this->get_output_cols() - 1) * this->get_stride_cols();
+}
+
+unsigned int DepthfirstStrategyUntyped::get_n_input_points() const { return this->get_input_rows() * this->get_input_cols(); }
+unsigned int DepthfirstStrategyUntyped::get_n_output_points() const { return this->get_output_rows() * this->get_output_cols(); }
+unsigned int DepthfirstStrategyUntyped::get_n_kernel_points() const { return this->get_kernel_rows() * this->get_kernel_cols(); }
+
+unsigned int DepthfirstStrategyUntyped::get_accumulator_depth_vl() const { return 1; }
+
+bool DepthfirstStrategyUntyped::get_kernel_packing_point(const unsigned int index, unsigned int &x, unsigned int &y) const
+{
+  // Get the kernel point to pack at the given index; return false to
+  // indicate that this index, and all greater indices, is out of range.
+  if (index < (this->get_kernel_cols() * this->get_kernel_rows()))
+  {
+    y = index % this->get_kernel_cols();
+    x = index / this->get_kernel_cols();
+    return true;
+  }
+  return false;
+}
+
+}  // namespace depthwise
+}  // namespace arm_conv