Move CPU/GPU files from Core/Runtime to the respective backend folders

Legacy structure contained two libraries core/runtime with two backends
in each.
We reduce the core/runtime libraries to a single library thus merging
the backend files

Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Change-Id: I69545765fe7a730368105cdbd067d3135ec7a174
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/6155
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/cpu/kernels/CpuGemmLowpMatrixMultiplyKernel.h b/src/cpu/kernels/CpuGemmLowpMatrixMultiplyKernel.h
new file mode 100644
index 0000000..083ee18
--- /dev/null
+++ b/src/cpu/kernels/CpuGemmLowpMatrixMultiplyKernel.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2017-2021 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_CPU_GEMMLOWP_MATRIXMULTIPLY_KERNEL_H
+#define ARM_COMPUTE_CPU_GEMMLOWP_MATRIXMULTIPLY_KERNEL_H
+
+#include "src/core/common/Macros.h"
+#include "src/cpu/ICpuKernel.h"
+
+namespace arm_compute
+{
+namespace cpu
+{
+namespace kernels
+{
+/** Kernel to multiply matrices
+ *
+ * @note @ref CpuGemmLowpMatrixMultiplyKernel low precision matrix product kernel
+ *  This kernel performs the following computation:
+ *
+ *  -# Convert a values from int8 to int32
+ *  -# Convert b values from int8 to int32
+ *  -# Compute the int32 matrix product of the resulting a * b and store the result as int32
+ *
+ */
+class CpuGemmLowpMatrixMultiplyKernel : public ICpuKernel
+{
+public:
+    /** Default constructor */
+    CpuGemmLowpMatrixMultiplyKernel() = default;
+    ARM_COMPUTE_DISALLOW_COPY_ALLOW_MOVE(CpuGemmLowpMatrixMultiplyKernel);
+    /** Initialise the kernel's input and output.
+     *
+     * The input matrices @p src0 and @p src1 must be the output of the kernels: @ref CpuGemmInterleave4x4Kernel and @ref CpuGemmTranspose1xWKernel. These two
+     * kernels change the layout of the original matrices to be more cache-friendly.
+     *
+     * @param[in]  src0 Input tensor info containing the interleaved Matrix A. Data type supported: U8/QASYMM8/S8/QASYMM8_SIGNED
+     * @param[in]  src1 Input tensor info containing the transposed1xW Matrix B. Data type supported: U8/QASYMM8/S8/QASYMM8_SIGNED/QSYMM8/QSYMM8_PER_CHANNEL
+     * @param[out] dst  Output tensor info to store the result of matrix multiplication. Data type supported: S32
+     */
+    void configure(const ITensorInfo *src0, const ITensorInfo *src1, ITensorInfo *dst);
+    /** Static function to check if given info will lead to a valid configuration
+     *
+     * Similar to CpuGemmLowpMatrixMultiplyKernel::configure()
+     *
+     * @return a status
+     */
+    static Status validate(const ITensorInfo *src0, const ITensorInfo *src1, const ITensorInfo *dst);
+
+    // Inherited methods overridden:
+    void run_op(ITensorPack &tensors, const Window &window, const ThreadInfo &info) override;
+    const char *name() const override;
+
+private:
+    bool _slide_matrix_b{ true };
+};
+} // namespace kernels
+} // namespace cpu
+} // namespace arm_compute
+#endif /*ARM_COMPUTE_CPU_GEMMLOWP_MATRIXMULTIPLY_KERNEL_H*/