chore: import upstream snapshot with attribution

test/speed/SoftmaxSpeed.cpp

@@ -0,0 +1,47 @@
+//
+//  SoftmaxSpeed.cpp
+//  MNNTests
+//
+//  Created by MNN on 2019/09/17.
+//  Copyright © 2018, Alibaba Group Holding Limited
+//
+
+#include <math.h>
+#include <MNN/expr/Expr.hpp>
+#include <MNN/expr/ExprCreator.hpp>
+#include <random>
+#define MNN_OPEN_TIME_TRACE
+#include <MNN/AutoTime.hpp>
+#include "MNNTestSuite.h"
+using namespace MNN::Express;
+#define TIME 100
+class SoftmaxSpeed : public MNNTestCase {
+public:
+    void SoftmaxTest() {
+        std::vector<std::tuple<int, int, int>> oci = {
+            {4096, 1024, 1},
+            {4096, 2, 1024},
+            {4096, 32, 32},
+        };
+        for (auto& iter : oci) {
+            auto outside = std::get<0>(iter);
+            auto axis = std::get<1>(iter);
+            auto inside = std::get<2>(iter);
+            auto x      = _Input({outside, axis, inside}, NCHW);
+            auto output = _Softmax(x, 1);
+            MNN::Timer _t;
+            for (int i = 0; i < TIME; ++i) {
+                x->writeMap<float>();
+                output->readMap<float>();
+            }
+            float cost = (float)_t.durationInUs()/1000.0f / (float)TIME;
+            MNN_PRINT("Test Speed for softmax outside:%d, axis:%d, inside:%d, run %d, avgtime: %f ms\n", outside, axis, inside, TIME, cost);
+
+        }
+    }
+    virtual bool run(int precision) {
+        SoftmaxTest();
+        return true;
+    }
+};
+MNNTestSuiteRegister(SoftmaxSpeed, "speed/Softmax");