chore: import upstream snapshot with attribution

test/grad/SeluGradTest.cpp

@@ -0,0 +1,54 @@
+//
+//  SeluGradTest.cpp
+//  MNNTests
+//
+//  Created by MNN on 2022/08/09.
+//  Copyright © 2018, Alibaba Group Holding Limited
+//
+
+#include <MNN/expr/Expr.hpp>
+#include <MNN/expr/ExprCreator.hpp>
+#include "MNNTestSuite.h"
+#include "TestUtils.h"
+#include "../tools/train/source/grad/OpGrad.hpp"
+
+using namespace MNN;
+using namespace MNN::Express;
+
+class SeluGradTest : public MNNTestCase {
+public:
+    char name[20] = "SELU";
+    virtual ~SeluGradTest() = default;
+
+    virtual bool run(int precision) {
+        const int len = 4;
+        auto input = _Input({len}, NCHW);
+        const float inpudata[] = {-1.0, -2.0, 0.0, 4.0};
+        auto inputPtr          = input->writeMap<float>();
+        memcpy(inputPtr, inpudata, len * sizeof(float));
+
+        float scale = 1.0507009873554804934193349852946f;
+        float alpha = 1.6732632423543772848170429916717f;
+        auto output = _Selu(input, scale, alpha);
+        auto opExpr = output->expr().first;
+
+        auto grad = OpGrad::get(opExpr->get()->type());
+        float outputDiff[len] = {0.1, -0.2, -0.3, 0.4};
+        auto inputGrad = grad->onGrad(opExpr, {_Const(outputDiff, {len})});
+
+        const std::vector<float> expectedOutput = {0.0647, -0.0476, -0.5274, 0.4203};
+        auto gotOutput = inputGrad[0]->readMap<float>();
+
+        for (int i = 0; i < len; ++i) {
+            auto diff = ::fabsf(gotOutput[i] - expectedOutput[i]);
+            if (diff > 0.0001) {
+                MNN_ERROR("%s grad test failed, expected: %f, but got: %f!\n", name, expectedOutput[i], gotOutput[i]);
+                return false;
+            }
+        }
+
+        return true;
+    }
+};
+
+MNNTestSuiteRegister(SeluGradTest, "grad/selu");