COMPMID-1759 NEON: Implement Reverse

Change-Id: I53852069ca223eb571a443e501278980fc60f3b4
Reviewed-on: https://review.mlplatform.org/474
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
diff --git a/src/core/NEON/kernels/NEReverseKernel.cpp b/src/core/NEON/kernels/NEReverseKernel.cpp
new file mode 100644
index 0000000..07d18f7
--- /dev/null
+++ b/src/core/NEON/kernels/NEReverseKernel.cpp
@@ -0,0 +1,220 @@
+/*
+ * Copyright (c) 2018-2019 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/NEON/kernels/NEReverseKernel.h"
+
+#include "arm_compute/core/AccessWindowStatic.h"
+#include "arm_compute/core/CPP/Validate.h"
+#include "arm_compute/core/Helpers.h"
+#include "arm_compute/core/ITensor.h"
+#include "arm_compute/core/NEON/NEAsymm.h"
+#include "arm_compute/core/NEON/NEFixedPoint.h"
+#include "arm_compute/core/NEON/NEMath.h"
+#include "arm_compute/core/NEON/wrapper/wrapper.h"
+#include "arm_compute/core/QAsymm8.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_neon.h>
+#include <array>
+#include <cmath>
+#include <map>
+
+namespace arm_compute
+{
+namespace
+{
+Status validate_arguments(const ITensorInfo *input, const ITensorInfo *output, const ITensorInfo *axis)
+{
+    ARM_COMPUTE_ERROR_ON_NULLPTR(input, output, axis);
+    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(input, 1, DataType::U8, DataType::S8, DataType::QASYMM8,
+                                                         DataType::U16, DataType::S16,
+                                                         DataType::U32, DataType::S32,
+                                                         DataType::F16, DataType::F32);
+    ARM_COMPUTE_RETURN_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(axis, 1, DataType::U32);
+    ARM_COMPUTE_RETURN_ERROR_ON_MSG(axis->num_dimensions() > 1, "Axis must be a 1D tensor");
+    ARM_COMPUTE_RETURN_ERROR_ON_MSG(axis->dimension(0) > 4, "Only up to 4 dimensions can be reversed");
+
+    // Checks performed when output is configured
+    if(output->total_size() != 0)
+    {
+        ARM_COMPUTE_RETURN_ERROR_ON_MISMATCHING_SHAPES(input, output);
+        ARM_COMPUTE_RETURN_ERROR_ON_MISMATCHING_DATA_TYPES(input, output);
+    }
+
+    return Status{};
+}
+} // namespace
+
+NEReverseKernel::NEReverseKernel()
+    : _input(nullptr), _output(nullptr), _axis(nullptr)
+{
+}
+
+void NEReverseKernel::configure(const ITensor *input, ITensor *output, const ITensor *axis)
+{
+    ARM_COMPUTE_ERROR_ON_NULLPTR(input, output, axis);
+
+    _input  = input;
+    _output = output;
+    _axis   = axis;
+
+    // Output tensor auto initialization if not yet initialized
+    auto_init_if_empty(*output->info(), *input->info()->clone());
+
+    ARM_COMPUTE_ERROR_THROW_ON(validate_arguments(input->info(), output->info(), axis->info()));
+
+    // Configure kernel window
+    INEKernel::configure(calculate_max_window(*output->info()));
+}
+
+Status NEReverseKernel::validate(const ITensorInfo *input, const ITensorInfo *output, const ITensorInfo *axis)
+{
+    ARM_COMPUTE_RETURN_ON_ERROR(validate_arguments(input, output, axis));
+
+    return Status{};
+}
+
+template <typename T>
+void run_reverse(const Window &window, const ITensor *input, const ITensor *axis, ITensor *output)
+{
+    int axis_bit = 0;
+    for(unsigned int i = 0; i < axis->info()->dimension(0); ++i)
+    {
+        const int axis_i = *(reinterpret_cast<const int *>(axis->buffer()) + i);
+        axis_bit |= 1 << axis_i;
+    }
+
+    // Check if we need a left-over loop for the y dimension
+    const int window_step_x            = 16 / input->info()->element_size();
+    const int window_start_x           = window.x().start();
+    const int window_end_x             = std::min(window.x().end(), static_cast<int>(input->info()->dimension(0)));
+    const int window_end_x_multiple_of = ((window_end_x - window_start_x) / window_step_x) * window_step_x;
+    bool      left_over_loop_x         = (((window_end_x - window_start_x) % window_step_x) != 0);
+
+    Window slice = window.first_slice_window_4D();
+
+    if(left_over_loop_x)
+    {
+        // Check if window_end_y_multiple_of is greater than window_start_y
+        if(window_end_x_multiple_of > window_start_x)
+        {
+            slice.set(Window::DimX, Window::Dimension(window_start_x, window_end_x_multiple_of, window_step_x));
+        }
+        else
+        {
+            slice.set(Window::DimX, Window::Dimension(0, 0, 1));
+        }
+    }
+
+    do
+    {
+        Iterator input_it(input, slice);
+        execute_window_loop(slice, [&](const Coordinates & id)
+        {
+            auto in = wrapper::vloadq(reinterpret_cast<T *>(input_it.ptr()));
+
+            // Reverse 0 axis
+            if(axis_bit & 0x1)
+            {
+                in = wrapper::vrev64(in);
+                in = wrapper::vcombine(wrapper::vgethigh(in), wrapper::vgetlow(in));
+            }
+
+            const int offset_x = (axis_bit & 0x1) ? output->info()->dimension(0) - id.x() - window_step_x : id.x();
+            const int offset_y = (axis_bit & 0x2) ? output->info()->dimension(1) - id.y() - 1 : id.y();
+            const int offset_z = (axis_bit & 0x4) ? output->info()->dimension(2) - id.z() - 1 : id.z();
+            const int offset_w = (axis_bit & 0x8) ? output->info()->dimension(3) - id[3] - 1 : id[3];
+
+            auto out_ptr = reinterpret_cast<T *>(output->ptr_to_element(Coordinates(offset_x, offset_y, offset_z, offset_w)));
+            wrapper::vstore(out_ptr, in);
+        },
+        input_it);
+
+        if(left_over_loop_x)
+        {
+            slice.set(Window::DimX, Window::Dimension(window_end_x_multiple_of, window_end_x, 1));
+
+            Iterator input_it(input, slice);
+
+            // Compute left-over elements along the y dimension (1x1)
+            execute_window_loop(slice, [&](const Coordinates & id)
+            {
+                const auto in = *reinterpret_cast<T *>(input_it.ptr());
+
+                const int offset_x = (axis_bit & 0x1) ? output->info()->dimension(0) - id.x() - 1 : id.x();
+                const int offset_y = (axis_bit & 0x2) ? output->info()->dimension(1) - id.y() - 1 : id.y();
+                const int offset_z = (axis_bit & 0x4) ? output->info()->dimension(2) - id.z() - 1 : id.z();
+                const int offset_w = (axis_bit & 0x8) ? output->info()->dimension(3) - id[3] - 1 : id[3];
+
+                *reinterpret_cast<T *>(output->ptr_to_element(Coordinates(offset_x, offset_y, offset_z, offset_w))) = in;
+            },
+            input_it);
+        }
+
+    }
+    while(window.slide_window_slice_4D(slice));
+}
+
+void NEReverseKernel::run(const Window &window, const ThreadInfo &info)
+{
+    ARM_COMPUTE_UNUSED(info);
+    ARM_COMPUTE_ERROR_ON_UNCONFIGURED_KERNEL(this);
+    ARM_COMPUTE_ERROR_ON_INVALID_SUBWINDOW(INEKernel::window(), window);
+
+    switch(_input->info()->data_type())
+    {
+        case DataType::F32:
+            run_reverse<float>(window, _input, _axis, _output);
+            break;
+#ifdef __ARM_FEATURE_FP16_VECTOR_ARITHMETIC
+        case DataType::F16:
+            run_reverse<float16_t>(window, _input, _axis, _output);
+            break;
+#endif // __ARM_FEATURE_FP16_VECTOR_ARITHMETIC
+        case DataType::U32:
+            run_reverse<uint32_t>(window, _input, _axis, _output);
+            break;
+        case DataType::S32:
+            run_reverse<int32_t>(window, _input, _axis, _output);
+            break;
+        case DataType::S16:
+            run_reverse<int16_t>(window, _input, _axis, _output);
+            break;
+        case DataType::U16:
+            run_reverse<uint16_t>(window, _input, _axis, _output);
+            break;
+        case DataType::QASYMM8:
+        case DataType::U8:
+            run_reverse<uint8_t>(window, _input, _axis, _output);
+            break;
+        case DataType::S8:
+            run_reverse<int8_t>(window, _input, _axis, _output);
+            break;
+        default:
+            ARM_COMPUTE_ERROR("Data type not supported");
+    }
+}
+} // namespace arm_compute
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