Merge autogradpp into PyTorch (#7074)

* Dump autogradpp into PyTorch

* Fixed up CMake for autogradpp/C++ API

* Made cereal a submodule

* Change search location of autogradpps mnist directory

* Add test_api to CI

* Download MNIST from the internet instead of storing in repo

* Fix warnings

.gitignore

@@ -55,6 +55,7 @@ test/.coverage
 test/data/legacy_serialized.pt
 test/data/linear.pt
 .mypy_cache
+test/cpp/api/mnist
 
 # IPython notebook checkpoints
 .ipynb_checkpoints

.gitmodules

@@ -77,3 +77,6 @@
 [submodule "third_party/ideep"]
 	path = third_party/ideep
 	url = https://github.com/intel/ideep.git
+[submodule "third_party/cereal"]
+	path = third_party/cereal
+	url = https://github.com/USCiLab/cereal

.jenkins/pytorch/test.sh

@@ -55,4 +55,6 @@ if [[ "$BUILD_TEST_LIBTORCH" == "1" ]]; then
    else
      "$CPP_BUILD"/libtorch/bin/test_jit "[cpu]"
    fi
+   python tools/download_mnist.py -d test/cpp/api/mnist
+   "$CPP_BUILD"/libtorch/bin/test_api
 fi

test/cpp/api/container_t.cpp

@@ -0,0 +1,258 @@
+#include "test.h"
+
+AUTOGRAD_CONTAINER_CLASS(TestModel) {
+ public:
+  void initialize_containers() override {
+    add(Linear(10, 3).make(), "l1");
+    add(Linear(3, 5).make(), "l2");
+    add(Linear(5, 100).make(), "l3");
+  }
+
+  variable_list forward(variable_list input) override { return input; };
+};
+
+AUTOGRAD_CONTAINER_CLASS(NestedModel) {
+ public:
+  void initialize_containers() override {
+    add(Linear(5, 20).make(), "l1");
+    add(TestModel().make(), "test");
+  }
+
+  void initialize_parameters() override {
+    add(Var(DefaultTensor(at::kFloat).tensor({3, 2, 21}), false), "param");
+  }
+
+  variable_list forward(variable_list input) override { return input; };
+};
+
+CASE("containers/conv2d/even") {
+  auto model = Conv2d(3, 2, 3).stride(2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({2, 3, 5, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 4);
+  EXPECT(s.ndimension() == 0);
+  for (auto i = 0; i < 4; i++) {
+    EXPECT(y.size(i) == 2);
+  }
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 3 * 2 * 3 * 3);
+};
+
+CASE("containers/conv2d/uneven") {
+  auto model = Conv2d(3, 2, IntVec({3, 2})).stride(2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({2, 3, 5, 4}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 4);
+  EXPECT(s.ndimension() == 0);
+  for (auto i = 0; i < 4; i++) {
+    EXPECT(y.size(i) == 2);
+  }
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 3 * 2 * 3 * 2);
+};
+
+CASE("containers/conv1d/even") {
+  auto model = Conv1d(3, 2, 3).stride(2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({2, 3, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 4);
+  EXPECT(s.ndimension() == 0);
+  for (auto i = 0; i < 3; i++) {
+    EXPECT(y.size(i) == 2);
+  }
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 3 * 2 * 3);
+};
+
+CASE("containers/conv3d/even") {
+  auto model = Conv3d(3, 2, 3).stride(2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({2, 3, 5, 5, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 5);
+  EXPECT(s.ndimension() == 0);
+  for (auto i = 0; i < 5; i++) {
+    EXPECT(y.size(i) == 2);
+  }
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 3 * 2 * 3 * 3 * 3);
+};
+
+CASE("containers/linear/basic1") {
+  auto model = Linear(5, 2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({10, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 2);
+  EXPECT(s.ndimension() == 0);
+  EXPECT(y.size(0) == 10);
+  EXPECT(y.size(1) == 2);
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 2 * 5);
+};
+
+CASE("containers/linear/sequential") {
+  auto model = ContainerList()
+    .append(Linear(10, 3).make())
+    .append(Linear(3, 5).make())
+    .append(Linear(5, 100).make())
+    .make();
+
+  auto x = Var(at::CPU(at::kFloat).randn({1000, 10}));
+  for (auto layer : *model) {
+    x = layer->forward({x})[0];
+    x = x.clamp_min(0);  // relu
+  }
+
+  backward(x);
+  EXPECT(x.ndimension() == 2);
+  EXPECT(x.size(0) == 1000);
+  EXPECT(x.size(1) == 100);
+  EXPECT(x.data().min().toCFloat() == 0);
+};
+
+CASE("containers/linear/simple") {
+  auto model = SimpleContainer().make();
+  auto l1 = model->add(Linear(10, 3).make(), "l1");
+  auto l2 = model->add(Linear(3, 5).make(), "l2");
+  auto l3 = model->add(Linear(5, 100).make(), "l3");
+
+  auto x = Var(at::CPU(at::kFloat).randn({1000, 10}));
+  x = l1->forward({x})[0].clamp_min(0);
+  x = l2->forward({x})[0].clamp_min(0);
+  x = l3->forward({x})[0].clamp_min(0);
+
+  backward(x);
+  EXPECT(x.ndimension() == 2);
+  EXPECT(x.size(0) == 1000);
+  EXPECT(x.size(1) == 100);
+  EXPECT(x.data().min().toCFloat() == 0);
+};
+
+CASE("containers/clone") {
+  auto model = TestModel().make();
+
+  auto model2 = model->clone();
+  auto m1param = model->parameters();
+  auto m2param = model2->parameters();
+  for (auto& param : m1param) {
+    EXPECT(param.second.allclose(m2param[param.first]));
+    param.second.data().mul_(2);
+  }
+  for (auto& param : m1param) {
+    EXPECT(!param.second.allclose(m2param[param.first]));
+  }
+};
+
+CASE("containers/embedding/basic") {
+  int dict_size = 10;
+  auto model = Embedding(dict_size, 2).make();
+  // Cannot get gradients to change indices (input) - only for embedding params
+  auto x = Var(at::CPU(at::kLong).tensor({10}).fill_(dict_size - 1), false);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 2);
+  EXPECT(s.ndimension() == 0);
+  EXPECT(y.size(0) == 10);
+  EXPECT(y.size(1) == 2);
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 2 * dict_size);
+};
+
+CASE("containers/embedding/list") {
+  auto model = Embedding(6, 4).make();
+  auto x = Var(at::CPU(at::kLong).tensor({2, 3}).fill_(5), false);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 3);
+  EXPECT(y.size(0) == 2);
+  EXPECT(y.size(1) == 3);
+  EXPECT(y.size(2) == 4);
+};
+
+CASE("containers/cuda/1") {
+  CUDA_GUARD;
+  auto model = Linear(5, 2).make();
+  model->cuda();
+  auto x = Var(at::CUDA(at::kFloat).randn({10, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 2);
+  EXPECT(s.ndimension() == 0);
+  EXPECT(y.size(0) == 10);
+  EXPECT(y.size(1) == 2);
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 2 * 5);
+};
+
+CASE("containers/cuda/2") {
+  CUDA_GUARD;
+  auto model = Linear(5, 2).make();
+  model->cuda();
+  model->cpu();
+  auto x = Var(at::CPU(at::kFloat).randn({10, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(y.ndimension() == 2);
+  EXPECT(s.ndimension() == 0);
+  EXPECT(y.size(0) == 10);
+  EXPECT(y.size(1) == 2);
+
+  EXPECT(model->parameters()["weight"].grad().numel() == 2 * 5);
+};
+
+CASE("containers/dropout/1") {
+  auto dropout = Dropout(0.5).make();
+  Variable x = Var(at::CPU(at::kFloat).ones(100));
+  Variable y = dropout->forward({x})[0];
+
+  backward(y);
+  EXPECT(y.ndimension() == 1);
+  EXPECT(y.size(0) == 100);
+  EXPECT(y.sum().toCFloat() < 130); // Probably
+  EXPECT(y.sum().toCFloat() > 70); // Probably
+
+  dropout->eval();
+  y = dropout->forward({x})[0];
+  EXPECT(y.data().sum().toCFloat() == 100);
+};
+
+CASE("containers/param") {
+  auto model = NestedModel().make();
+  EXPECT(model->param("param").size(0) == 3);
+  EXPECT(model->param("param").size(1) == 2);
+  EXPECT(model->param("param").size(2) == 21);
+  EXPECT(model->param("l1.bias").size(0) == 20);
+  EXPECT(model->param("l1.weight").size(0) == 20);
+  EXPECT(model->param("l1.weight").size(1) == 5);
+  EXPECT(model->param("test.l1.bias").size(0) == 3);
+  EXPECT(model->param("test.l1.weight").size(0) == 3);
+  EXPECT(model->param("test.l1.weight").size(1) == 10);
+  EXPECT(model->param("test.l2.bias").size(0) == 5);
+  EXPECT(model->param("test.l2.weight").size(0) == 5);
+  EXPECT(model->param("test.l2.weight").size(1) == 3);
+  EXPECT(model->param("test.l3.bias").size(0) == 100);
+  EXPECT(model->param("test.l3.weight").size(0) == 100);
+  EXPECT(model->param("test.l3.weight").size(1) == 5);
+}

test/cpp/api/integration_t.cpp

@@ -0,0 +1,355 @@
+#include "test.h"
+
+class CartPole {
+  // Translated from openai/gym's cartpole.py
+  public:
+    double gravity = 9.8;
+    double masscart = 1.0;
+    double masspole = 0.1;
+    double total_mass = (masspole + masscart);
+    double length = 0.5; // actually half the pole's length;
+    double polemass_length = (masspole * length);
+    double force_mag = 10.0;
+    double tau = 0.02;  // seconds between state updates;
+
+    // Angle at which to fail the episode
+    double theta_threshold_radians = 12 * 2 * M_PI / 360;
+    double x_threshold = 2.4;
+    int steps_beyond_done = -1;
+
+    at::Tensor state;
+    double reward;
+    bool done;
+    int step_ = 0;
+
+    at::Tensor getState() {
+      return state;
+    }
+
+    double getReward() {
+      return reward;
+    }
+
+    double isDone() {
+      return done;
+    }
+
+    void reset() {
+      state = at::CPU(at::kFloat).tensor({4}).uniform_(-0.05, 0.05);
+      steps_beyond_done = -1;
+      step_ = 0;
+    }
+
+    CartPole() {
+      reset();
+    }
+
+    void step(int action) {
+      auto x = state[0].toCFloat();
+      auto x_dot = state[1].toCFloat();
+      auto theta = state[2].toCFloat();
+      auto theta_dot = state[3].toCFloat();
+
+      auto force = (action == 1) ? force_mag : -force_mag;
+      auto costheta = std::cos(theta);
+      auto sintheta = std::sin(theta);
+      auto temp = (force + polemass_length * theta_dot * theta_dot * sintheta) / total_mass;
+      auto thetaacc = (gravity * sintheta - costheta* temp) / (length * (4.0/3.0 - masspole * costheta * costheta / total_mass));
+      auto xacc  = temp - polemass_length * thetaacc * costheta / total_mass;
+
+      x  = x + tau * x_dot;
+      x_dot = x_dot + tau * xacc;
+      theta = theta + tau * theta_dot;
+      theta_dot = theta_dot + tau * thetaacc;
+      state[0] = x;
+      state[1] = x_dot;
+      state[2] = theta;
+      state[3] = theta_dot;
+      done =  x < - x_threshold
+           || x > x_threshold
+           || theta < -theta_threshold_radians
+           || theta > theta_threshold_radians
+           || step_ > 200;
+
+      if (!done) {
+        reward = 1.0;
+      } else if (steps_beyond_done == -1) {
+        // Pole just fell!
+        steps_beyond_done = 0;
+        reward = 0;
+      } else {
+        if (steps_beyond_done == 0) {
+          assert(false); // Can't do this
+        }
+      }
+      step_++;
+
+    };
+};
+
+template <typename M, typename F, typename O>
+bool test_mnist(uint32_t batch_size, uint32_t num_epochs, bool useGPU,
+     M&& model, F&& forward_op, O&& optim) {
+   std::cout << "Training MNIST for " << num_epochs << " epochs, rest your eyes for a bit!\n";
+   struct MNIST_Reader
+   {
+     FILE *fp_;
+
+     MNIST_Reader(const char *path) {
+       fp_ = fopen(path, "rb");
+       if (!fp_) throw std::runtime_error("failed to open file");
+     }
+
+     ~MNIST_Reader() { if (fp_) fclose(fp_); }
+
+     int32_t read_int() {
+       uint8_t buf[4];
+       if (fread(buf, sizeof(buf), 1, fp_) != 1) throw std::runtime_error("failed to read an integer");
+       return int32_t(buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3]);
+     }
+
+     uint8_t read_byte() {
+       uint8_t i;
+       if (fread(&i, sizeof(i), 1, fp_) != 1) throw std::runtime_error("failed to read an byte");
+       return i;
+     }
+   };
+
+   auto readData = [&](std::string fn) {
+     MNIST_Reader rd(fn.c_str());
+
+     /* int image_magic = */ rd.read_int();
+     int image_count = rd.read_int();
+     int image_rows = rd.read_int();
+     int image_cols = rd.read_int();
+
+     auto data = at::CPU(at::kFloat).tensor({image_count, 1, image_rows, image_cols});
+     auto a_data = data.accessor<float, 4>();
+
+     for (int c = 0; c < image_count; c++) {
+       for (int i = 0; i < image_rows; i++) {
+         for (int j = 0; j < image_cols; j++) {
+           a_data[c][0][i][j] = float(rd.read_byte()) / 255;
+         }
+       }
+     }
+
+     return data.toBackend(useGPU ? at::kCUDA : at::kCPU);
+   };
+
+   auto readLabels = [&](std::string fn) {
+     MNIST_Reader rd(fn.c_str());
+     /* int label_magic = */ rd.read_int();
+     int label_count = rd.read_int();
+
+     auto data = at::CPU(at::kLong).tensor({label_count});
+     auto a_data = data.accessor<int64_t, 1>();
+
+     for (int i = 0; i < label_count; ++i) {
+       a_data[i] = long(rd.read_byte());
+     }
+     return data.toBackend(useGPU ? at::kCUDA : at::kCPU);
+   };
+
+   auto trdata = readData("test/cpp/api/mnist/train-images-idx3-ubyte");
+   auto trlabel = readLabels("test/cpp/api/mnist/train-labels-idx1-ubyte");
+   auto tedata = readData("test/cpp/api/mnist/t10k-images-idx3-ubyte");
+   auto telabel = readLabels("test/cpp/api/mnist/t10k-labels-idx1-ubyte");
+
+   if (useGPU) {
+     model->cuda();
+   }
+
+   for (auto epoch = 0U; epoch < num_epochs; epoch++) {
+     auto shuffled_inds = std::vector<int>(trdata.size(0));
+     for (int i=0; i < trdata.size(0); i++) {
+      shuffled_inds[i] = i;
+     }
+     std::random_shuffle(shuffled_inds.begin(), shuffled_inds.end());
+
+     auto inp = (useGPU ? at::CUDA : at::CPU)(at::kFloat).tensor({batch_size, 1, trdata.size(2), trdata.size(3)});
+     auto lab = (useGPU ? at::CUDA : at::CPU)(at::kLong).tensor({batch_size});
+     for (auto p = 0U; p < shuffled_inds.size() - batch_size; p++) {
+       inp[p % batch_size] = trdata[shuffled_inds[p]];
+       lab[p % batch_size] = trlabel[shuffled_inds[p]];
+
+       if (p % batch_size != batch_size - 1) continue;
+       Variable x = forward_op(Var(inp));
+       Variable y = Var(lab, false);
+       Variable loss = at::nll_loss(x, y);
+
+       optim->zero_grad();
+       backward(loss);
+       optim->step();
+     }
+   }
+
+   no_grad_guard guard;
+   auto result = std::get<1>(forward_op(Var(tedata, false)).max(1));
+   Variable correct = (result == Var(telabel)).toType(at::kFloat);
+   std::cout << "Num correct: " << correct.data().sum().toCFloat()
+     << " out of " << telabel.size(0) << std::endl;
+   return correct.data().sum().toCFloat() > telabel.size(0) * 0.8;
+ };
+
+CASE("integration/RL/cartpole") {
+  std::cout << "Training episodic policy gradient with a critic for up to 3000"
+    " episodes, rest your eyes for a bit!\n";
+  auto model = SimpleContainer().make();
+  auto linear = model->add(Linear(4, 128).make(), "linear");
+  auto policyHead = model->add(Linear(128, 2).make(), "policy");
+  auto valueHead = model->add(Linear(128, 1).make(), "action");
+  auto optim = Adam(model, 1e-3).make();
+
+  std::vector<Variable> saved_log_probs;
+  std::vector<Variable> saved_values;
+  std::vector<float> rewards;
+
+  auto forward = [&](variable_list inp) {
+    auto x = linear->forward(inp)[0].clamp_min(0);
+    Variable actions = policyHead->forward({x})[0];
+    Variable value = valueHead->forward({x})[0];
+    return std::make_tuple(at::softmax(actions, -1), value);
+  };
+
+   auto selectAction = [&](at::Tensor state) {
+     // Only work on single state right now, change index to gather for batch
+     auto out = forward({Var(state, false)});
+     auto probs = Variable(std::get<0>(out));
+     auto value = Variable(std::get<1>(out));
+     auto action = probs.data().multinomial(1)[0].toCInt();
+     // Compute the log prob of a multinomial distribution.
+     // This should probably be actually implemented in autogradpp...
+     auto p = probs / probs.sum(-1, true);
+     auto log_prob = p[action].log();
+     saved_log_probs.push_back(log_prob);
+     saved_values.push_back(value);
+     return action;
+   };
+
+  auto finishEpisode = [&]() {
+    auto R = 0.;
+    for (int i = rewards.size() - 1; i >= 0; i--) {
+      R = rewards[i] + 0.99 * R;
+      rewards[i] = R;
+    }
+    auto r_t = at::CPU(at::kFloat).tensorFromBlob(rewards.data(), {static_cast<int64_t>(rewards.size())});
+    r_t = (r_t - r_t.mean()) / (r_t.std() + 1e-5);
+
+    std::vector<at::Tensor> policy_loss;
+    std::vector<at::Tensor> value_loss;
+    for (auto i = 0U; i < saved_log_probs.size(); i++) {
+      auto r = rewards[i] - saved_values[i].toCFloat();
+      policy_loss.push_back(- r * saved_log_probs[i]);
+      value_loss.push_back(at::smooth_l1_loss(saved_values[i], Var(at::CPU(at::kFloat).scalarTensor(at::Scalar(rewards[i])), false)));
+    }
+    auto loss = at::stack(policy_loss).sum() + at::stack(value_loss).sum();
+
+    optim->zero_grad();
+    backward(loss);
+    optim->step();
+
+    rewards.clear();
+    saved_log_probs.clear();
+    saved_values.clear();
+  };
+
+  auto env = CartPole();
+  double running_reward = 10.0;
+  for (auto episode = 0; ; episode++) {
+    env.reset();
+    auto state = env.getState();
+    int t = 0;
+    for ( ; t < 10000; t++) {
+      auto action = selectAction(state);
+      env.step(action);
+      state = env.getState();
+      auto reward = env.getReward();
+      auto done = env.isDone();
+
+      rewards.push_back(reward);
+      if (done) break;
+    }
+
+    running_reward = running_reward * 0.99 + t * 0.01;
+    finishEpisode();
+    /*
+    if (episode % 10 == 0) {
+      printf("Episode %i\tLast length: %5d\tAverage length: %.2f\n",
+              episode, t, running_reward);
+    }
+    */
+    if (running_reward > 150) break;
+    EXPECT(episode < 3000);
+  }
+}
+
+CASE("integration/mnist") {  // ~ will make it run last :D
+  CUDA_GUARD;
+  auto model = SimpleContainer().make();
+  auto conv1 = model->add(Conv2d(1, 10, 5).make(), "conv1");
+  auto conv2 = model->add(Conv2d(10, 20, 5).make(), "conv2");
+  auto drop = Dropout(0.3).make();
+  auto drop2d = Dropout2d(0.3).make();
+  auto linear1 = model->add(Linear(320, 50).make(), "linear1");
+  auto linear2 = model->add(Linear(50, 10).make(), "linear2");
+
+  auto forward = [&](Variable x) {
+    x = std::get<0>(at::max_pool2d(conv1->forward({x})[0], {2, 2})).clamp_min(0);
+    x = conv2->forward({x})[0];
+    x = drop2d->forward({x})[0];
+    x = std::get<0>(at::max_pool2d(x, {2, 2})).clamp_min(0);
+
+    x = x.view({-1, 320});
+    x = linear1->forward({x})[0].clamp_min(0);
+    x = drop->forward({x})[0];
+    x = linear2->forward({x})[0];
+    x = at::log_softmax(x, 1);
+    return x;
+  };
+
+  auto optim = SGD(model, 1e-2).momentum(0.5).make();
+
+  EXPECT(test_mnist(
+      32,  // batch_size
+      3,  // num_epochs
+      true,  // useGPU
+      model, forward, optim));
+};
+
+CASE("integration/mnist_batchnorm") {  // ~ will make it run last :D
+  CUDA_GUARD;
+  auto model = SimpleContainer().make();
+  auto conv1 = model->add(Conv2d(1, 10, 5).make(), "conv1");
+  auto batchnorm2d = model->add(
+      BatchNorm(10).stateful().make(),
+      "batchnorm2d");
+  auto conv2 = model->add(Conv2d(10, 20, 5).make(), "conv2");
+  auto linear1 = model->add(Linear(320, 50).make(), "linear1");
+  auto batchnorm1 = model->add(
+      BatchNorm(50).stateful().make(),
+      "batchnorm1");
+  auto linear2 = model->add(Linear(50, 10).make(), "linear2");
+
+  auto forward = [&](Variable x) {
+    x = std::get<0>(at::max_pool2d(conv1->forward({x})[0], {2, 2})).clamp_min(0);
+    x = batchnorm2d->forward({x})[0];
+    x = conv2->forward({x})[0];
+    x = std::get<0>(at::max_pool2d(x, {2, 2})).clamp_min(0);
+
+    x = x.view({-1, 320});
+    x = linear1->forward({x})[0].clamp_min(0);
+    x = batchnorm1->forward({x})[0];
+    x = linear2->forward({x})[0];
+    x = at::log_softmax(x, 1);
+    return x;
+  };
+
+  auto optim = SGD(model, 1e-2).momentum(0.5).make();
+
+  EXPECT(test_mnist(
+      32,  // batch_size
+      3,  // num_epochs
+      true,  // useGPU
+      model, forward, optim));
+};

test/cpp/api/misc_t.cpp

@@ -0,0 +1,35 @@
+#include "test.h"
+
+CASE("misc/no_grad/1") {
+  no_grad_guard guard;
+  auto model = Linear(5, 2).make();
+  auto x = Var(at::CPU(at::kFloat).randn({10, 5}), true);
+  auto y = model->forward({x})[0];
+  Variable s = y.sum();
+
+  backward(s);
+  EXPECT(!model->parameters()["weight"].grad().defined());
+};
+
+CASE("misc/random/seed_cpu") {
+  int size = 100;
+  setSeed(7);
+  auto x1 = Var(at::CPU(at::kFloat).randn({size}));
+  setSeed(7);
+  auto x2 = Var(at::CPU(at::kFloat).randn({size}));
+
+  auto l_inf = (x1.data() - x2.data()).abs().max().toCFloat();
+  EXPECT(l_inf < 1e-10);
+};
+
+CASE("misc/random/seed_cuda") {
+  CUDA_GUARD;
+  int size = 100;
+  setSeed(7);
+  auto x1 = Var(at::CUDA(at::kFloat).randn({size}));
+  setSeed(7);
+  auto x2 = Var(at::CUDA(at::kFloat).randn({size}));
+
+  auto l_inf = (x1.data() - x2.data()).abs().max().toCFloat();
+  EXPECT(l_inf < 1e-10);
+};

test/cpp/api/optim_t.cpp

@@ -0,0 +1,99 @@
+#include "test.h"
+
+bool test_optimizer_xor(Optimizer optim, std::shared_ptr<ContainerList> model) {
+  float running_loss = 1;
+  int epoch = 0;
+  while (running_loss > 0.1) {
+    auto bs = 4U;
+    auto inp = at::CPU(at::kFloat).tensor({bs, 2});
+    auto lab = at::CPU(at::kFloat).tensor({bs});
+    for (auto i = 0U; i < bs; i++) {
+      auto a = std::rand() % 2;
+      auto b = std::rand() % 2;
+      auto c = a ^ b;
+      inp[i][0] = a;
+      inp[i][1] = b;
+      lab[i] = c;
+    }
+    // forward
+    auto x = Var(inp);
+    auto y = Var(lab, false);
+    for (auto layer : *model) x = layer->forward({x})[0].sigmoid_();
+    Variable loss = at::binary_cross_entropy(x, y);
+
+    optim->zero_grad();
+    backward(loss);
+    optim->step();
+
+    running_loss = running_loss * 0.99 + loss.data().sum().toCFloat() * 0.01;
+    if (epoch > 3000) {
+      return false;
+    }
+    epoch++;
+  }
+  return true;
+}
+
+CASE("optim/sgd") {
+  auto model = ContainerList()
+    .append(Linear(2, 8).make())
+    .append(Linear(8, 1).make())
+    .make();
+
+  auto optim = SGD(model, 1e-1).momentum(0.9).nesterov().weight_decay(1e-6).make();
+  EXPECT(test_optimizer_xor(optim, model));
+}
+
+CASE("optim/adagrad") {
+  auto model = ContainerList()
+    .append(Linear(2, 8).make())
+    .append(Linear(8, 1).make())
+    .make();
+
+  auto optim = Adagrad(model, 1.0).weight_decay(1e-6).lr_decay(1e-3).make();
+  EXPECT(test_optimizer_xor(optim, model));
+}
+
+CASE("optim/rmsprop") {
+  {
+    auto model = ContainerList()
+      .append(Linear(2, 8).make())
+      .append(Linear(8, 1).make())
+      .make();
+
+    auto optim = RMSprop(model, 1e-1).momentum(0.9).weight_decay(1e-6).make();
+    EXPECT(test_optimizer_xor(optim, model));
+  }
+
+  {
+    auto model = ContainerList()
+      .append(Linear(2, 8).make())
+      .append(Linear(8, 1).make())
+      .make();
+
+    auto optim = RMSprop(model, 1e-1).centered().make();
+    EXPECT(test_optimizer_xor(optim, model));
+  }
+}
+
+CASE("optim/adam") {
+  auto model = ContainerList()
+    .append(Linear(2, 8).make())
+    .append(Linear(8, 1).make())
+    .make();
+
+  auto optim = Adam(model, 1.0).weight_decay(1e-6).make();
+  EXPECT(test_optimizer_xor(optim, model));
+}
+
+CASE("optim/amsgrad") {
+  auto model = ContainerList()
+    .append(Linear(2, 8).make())
+    .append(Linear(8, 1).make())
+    .make();
+
+  auto optim = Adam(model, 0.1).weight_decay(1e-6).amsgrad().make();
+  EXPECT(test_optimizer_xor(optim, model));
+}
+
+

test/cpp/api/rnn_t.cpp

@@ -0,0 +1,168 @@
+#include "test.h"
+
+template <typename R, typename Func>
+bool test_RNN_xor(Func&& model_maker, bool cuda = false) {
+  auto nhid = 32;
+  auto model = SimpleContainer().make();
+  auto l1 = model->add(Linear(1, nhid).make(), "l1");
+  auto rnn = model->add(model_maker(nhid), "rnn");
+  auto lo = model->add(Linear(nhid, 1).make(), "lo");
+
+  auto optim = Adam(model, 1e-2).make();
+
+  auto forward_op = [&](Variable x) {
+    auto T = x.size(0);
+    auto B = x.size(1);
+    x = x.view({T * B, 1});
+    x = l1->forward({x})[0].view({T, B, nhid}).tanh_();
+    x = rnn->forward({x})[0][T-1];
+    x = lo->forward({x})[0];
+    return x;
+  };
+
+  if (cuda) {
+    model->cuda();
+  }
+
+  float running_loss = 1;
+  int epoch = 0;
+  auto max_epoch = 1500;
+  while (running_loss > 1e-2) {
+    auto bs = 16U;
+    auto nlen = 5U;
+    auto inp = at::CPU(at::kFloat).rand({nlen, bs, 1}).round().toType(at::kFloat);
+    auto lab = inp.sum(0);
+
+    if (cuda) {
+      inp = inp.toBackend(at::kCUDA);
+      lab = lab.toBackend(at::kCUDA);
+    }
+
+    auto x = Var(inp);
+    auto y = Var(lab, false);
+    x = forward_op(x);
+    Variable loss = at::mse_loss(x, y);
+
+    optim->zero_grad();
+    backward(loss);
+    optim->step();
+
+    running_loss = running_loss * 0.99 + loss.toCFloat() * 0.01;
+    if (epoch > max_epoch) {
+      return false;
+    }
+    epoch++;
+  }
+  return true;
+};
+
+CASE("RNN/LSTM/sizes") {
+  auto model = LSTM(128, 64).nlayers(2).dropout(0.2).make();
+  Variable x = Var(at::CPU(at::kFloat).randn({10, 16, 128}));
+  auto tup = model->forward({x});
+  auto y = x.mean();
+
+  auto out = tup[0];
+  auto hids = tup[1];
+
+  backward(y);
+  EXPECT(out.ndimension() == 3);
+  EXPECT(out.size(0) == 10);
+  EXPECT(out.size(1) == 16);
+  EXPECT(out.size(2) == 64);
+
+  EXPECT(hids.ndimension() == 4);
+  EXPECT(hids.size(0) == 2);  // 2 layers
+  EXPECT(hids.size(1) == 2);  // c and h
+  EXPECT(hids.size(2) == 16); // Batch size of 16
+  EXPECT(hids.size(3) == 64); // 64 hidden dims
+
+  // Something is in the hiddens
+  EXPECT(hids.norm().toCFloat() > 0);
+
+  Variable diff = model->forward({x, hids})[1] - hids;
+
+  // Hiddens changed
+  EXPECT(diff.data().abs().sum().toCFloat() > 1e-3);
+};
+
+CASE("RNN/LSTM/outputs") {
+  // Make sure the outputs match pytorch outputs
+  auto model = LSTM(2, 2).make();
+  for (auto& v : model->parameters()) {
+    float size = v.second.numel();
+    auto p = static_cast<float*>(v.second.data().storage()->data());
+    for (size_t i = 0; i < size; i++) {
+      p[i] = i/size;
+    }
+  }
+
+  Variable x = Var(at::CPU(at::kFloat).tensor({3, 4, 2}));
+  float size = x.data().numel();
+  auto p = static_cast<float*>(x.data().storage()->data());
+  for (size_t i = 0; i < size; i++) {
+    p[i] = (size - i) / size;
+  }
+
+  auto out = model->forward({x});
+  EXPECT(out[0].ndimension() == 3);
+  EXPECT(out[0].size(0) == 3);
+  EXPECT(out[0].size(1) == 4);
+  EXPECT(out[0].size(2) == 2);
+
+  auto flat = out[0].data().view(3*4*2);
+  float c_out[] =  {0.4391, 0.5402, 0.4330, 0.5324, 0.4261, 0.5239, 0.4183, 
+    0.5147, 0.6822, 0.8064, 0.6726, 0.7968, 0.6620, 0.7860, 0.6501, 0.7741, 
+    0.7889, 0.9003, 0.7769, 0.8905, 0.7635, 0.8794, 0.7484, 0.8666};
+  for (size_t i = 0; i < 3*4*2; i++) {
+    EXPECT(std::abs(flat[i].toCFloat() - c_out[i]) < 1e-3);
+  }
+
+  EXPECT(out[1].ndimension() == 4); // T x (hx, cx) x B x 2
+  EXPECT(out[1].size(0) == 1);
+  EXPECT(out[1].size(1) == 2);
+  EXPECT(out[1].size(2) == 4);
+  EXPECT(out[1].size(3) == 2);
+  flat = out[1].data().view(16);
+  float h_out[] = {0.7889, 0.9003, 0.7769, 0.8905, 0.7635, 0.8794, 0.7484,
+    0.8666, 1.1647, 1.6106, 1.1425, 1.5726, 1.1187, 1.5329, 1.0931, 1.4911};
+  for (size_t i = 0; i < 16; i++) {
+    EXPECT(std::abs(flat[i].toCFloat() - h_out[i]) < 1e-3);
+  }
+};
+
+CASE("integration/RNN/LSTM") {
+  EXPECT(test_RNN_xor<LSTM>([](int s) { return LSTM(s, s).nlayers(2).make(); }));
+};
+
+CASE("integration/RNN/GRU") {
+  EXPECT(test_RNN_xor<GRU>([](int s) { return GRU(s, s).nlayers(2).make(); }));
+};
+
+CASE("integration/RNN/RNN/Relu") {
+  EXPECT(test_RNN_xor<RNN>([](int s) { return RNN(s, s, RNN::Mode::Relu).nlayers(2).make(); }));
+};
+
+CASE("integration/RNN/RNN/Tanh") {
+  EXPECT(test_RNN_xor<RNN>([](int s) { return RNN(s, s, RNN::Mode::Tanh).nlayers(2).make(); }));
+};
+
+CASE("integration/RNN/cuda/LSTM") {
+  CUDA_GUARD;
+  EXPECT(test_RNN_xor<LSTM>([](int s) { return LSTM(s, s).nlayers(2).make(); }, true));
+};
+
+CASE("integration/RNN/cuda/GRU") {
+  CUDA_GUARD;
+  EXPECT(test_RNN_xor<GRU>([](int s) { return GRU(s, s).nlayers(2).make(); }, true));
+};
+
+CASE("integration/RNN/cuda/RNN/Relu") {
+  CUDA_GUARD;
+  EXPECT(test_RNN_xor<RNN>([](int s) { return RNN(s, s, RNN::Mode::Relu).nlayers(2).make(); }, true));
+};
+
+CASE("integration/RNN/cuda/RNN/Tanh") {
+  CUDA_GUARD;
+  EXPECT(test_RNN_xor<RNN>([](int s) { return RNN(s, s, RNN::Mode::Tanh).nlayers(2).make(); }, true));
+};

test/cpp/api/serialization_t.cpp

@@ -0,0 +1,261 @@
+#include "test.h"
+
+#include "cereal/archives/portable_binary.hpp"
+
+CASE("serialization/undefined") {
+  auto x = at::Tensor();
+
+  EXPECT(!x.defined());
+
+  auto y = at::CPU(at::kFloat).randn({5});
+
+  std::stringstream ss;
+  save(ss, &x);
+  load(ss, &y);
+
+  EXPECT(!y.defined());
+}
+
+CASE("serialization/cputypes") {
+  for (int i = 0; i < static_cast<int>(at::ScalarType::NumOptions); i++) {
+    if (i == static_cast<int>(at::ScalarType::Half)) {
+      // XXX can't serialize half tensors at the moment since contiguous() is
+      // not implemented for this type;
+      continue;
+    } else if (i == static_cast<int>(at::ScalarType::Undefined)) {
+      // We can't construct a tensor for this type. This is tested in
+      // serialization/undefined anyway.
+      continue;
+    }
+
+    auto x =
+        at::getType(at::kCPU, static_cast<at::ScalarType>(i)).ones({5, 5});
+    auto y = at::Tensor();
+
+    std::stringstream ss;
+    save(ss, &x);
+    load(ss, &y);
+
+    EXPECT(y.defined());
+    EXPECT(x.sizes().vec() == y.sizes().vec());
+    if (at::isIntegralType(static_cast<at::ScalarType>(i))) {
+      EXPECT(x.equal(y));
+    } else {
+      EXPECT(x.allclose(y));
+    }
+  }
+}
+
+CASE("serialization/binary") {
+  auto x = at::CPU(at::kFloat).randn({5, 5});
+  auto y = at::Tensor();
+
+  std::stringstream ss;
+  {
+    cereal::BinaryOutputArchive archive(ss);
+    archive(x);
+  }
+  {
+    cereal::BinaryInputArchive archive(ss);
+    archive(y);
+  }
+
+  EXPECT(y.defined());
+  EXPECT(x.sizes().vec() == y.sizes().vec());
+  EXPECT(x.allclose(y));
+}
+
+CASE("serialization/portable_binary") {
+  auto x = at::CPU(at::kFloat).randn({5, 5});
+  auto y = at::Tensor();
+
+  std::stringstream ss;
+  {
+    cereal::PortableBinaryOutputArchive archive(ss);
+    archive(x);
+  }
+  {
+    cereal::PortableBinaryInputArchive archive(ss);
+    archive(y);
+  }
+
+  EXPECT(y.defined());
+  EXPECT(x.sizes().vec() == y.sizes().vec());
+  EXPECT(x.allclose(y));
+}
+
+CASE("serialization/resized") {
+  auto x = at::CPU(at::kFloat).randn({11, 5});
+  x.resize_({5, 5});
+  auto y = at::Tensor();
+
+  std::stringstream ss;
+  {
+    cereal::BinaryOutputArchive archive(ss);
+    archive(x);
+  }
+  {
+    cereal::BinaryInputArchive archive(ss);
+    archive(y);
+  }
+
+  EXPECT(y.defined());
+  EXPECT(x.sizes().vec() == y.sizes().vec());
+  EXPECT(x.allclose(y));
+}
+
+CASE("serialization/sliced") {
+  auto x = at::CPU(at::kFloat).randn({11, 5});
+  x = x.slice(0, 1, 3);
+  auto y = at::Tensor();
+
+  std::stringstream ss;
+  {
+    cereal::BinaryOutputArchive archive(ss);
+    archive(x);
+  }
+  {
+    cereal::BinaryInputArchive archive(ss);
+    archive(y);
+  }
+
+  EXPECT(y.defined());
+  EXPECT(x.sizes().vec() == y.sizes().vec());
+  EXPECT(x.allclose(y));
+}
+
+CASE("serialization/noncontig") {
+  auto x = at::CPU(at::kFloat).randn({11, 5});
+  x = x.slice(1, 1, 4);
+  auto y = at::Tensor();
+
+  std::stringstream ss;
+  {
+    cereal::BinaryOutputArchive archive(ss);
+    archive(x);
+  }
+  {
+    cereal::BinaryInputArchive archive(ss);
+    archive(y);
+  }
+
+  EXPECT(y.defined());
+  EXPECT(x.sizes().vec() == y.sizes().vec());
+  EXPECT(x.allclose(y));
+}
+
+CASE("serialization/xor") {
+  // We better be able to save and load a XOR model!
+  auto makeModel = []() {
+    return ContainerList()
+      .append(Linear(2, 8).make())
+      .append(Linear(8, 1).make())
+      .make();
+  };
+  auto getLoss = [](std::shared_ptr<ContainerList> model, uint32_t bs) {
+    auto inp = at::CPU(at::kFloat).tensor({bs, 2});
+    auto lab = at::CPU(at::kFloat).tensor({bs});
+    for (auto i = 0U; i < bs; i++) {
+      auto a = std::rand() % 2;
+      auto b = std::rand() % 2;
+      auto c = a ^ b;
+      inp[i][0] = a;
+      inp[i][1] = b;
+      lab[i] = c;
+    }
+
+    // forward
+    auto x = Var(inp);
+    auto y = Var(lab, false);
+    for (auto layer : *model) x = layer->forward({x})[0].sigmoid_();
+    return at::binary_cross_entropy(x, y);
+  };
+
+  auto model = makeModel();
+  auto model2 = makeModel();
+  auto model3 = makeModel();
+  auto optim = SGD(model, 1e-1).momentum(0.9).nesterov().weight_decay(1e-6).make();
+
+  float running_loss = 1;
+  int epoch = 0;
+  while (running_loss > 0.1) {
+    Variable loss = getLoss(model, 4);
+    optim->zero_grad();
+    backward(loss);
+    optim->step();
+
+    running_loss = running_loss * 0.99 + loss.data().sum().toCFloat() * 0.01;
+    EXPECT(epoch < 3000);
+    epoch++;
+  }
+
+  std::stringstream ss;
+  save(ss, model);
+  load(ss, model2);
+
+  auto loss = getLoss(model2, 100);
+  EXPECT(loss.toCFloat() < 0.1);
+
+  CUDA_GUARD;
+  model2->cuda();
+  ss.clear();
+  save(ss, model2);
+  load(ss, model3);
+
+  loss = getLoss(model3, 100);
+  EXPECT(loss.toCFloat() < 0.1);
+}
+
+CASE("serialization/optim") {
+  auto model1 = Linear(5, 2).make();
+  auto model2 = Linear(5, 2).make();
+  auto model3 = Linear(5, 2).make();
+
+  // Models 1, 2, 3 will have the same params
+  std::stringstream ss;
+  save(ss, model1);
+  load(ss, model2);
+  ss.seekg(0, std::ios::beg);
+  load(ss, model3);
+
+  // Make some optimizers with momentum (and thus state)
+  auto optim1 = SGD(model1, 1e-1).momentum(0.9).make();
+  auto optim2 = SGD(model2, 1e-1).momentum(0.9).make();
+  auto optim2_2 = SGD(model2, 1e-1).momentum(0.9).make();
+  auto optim3 = SGD(model3, 1e-1).momentum(0.9).make();
+  auto optim3_2 = SGD(model3, 1e-1).momentum(0.9).make();
+
+  auto x = Var(at::CPU(at::kFloat).ones({10, 5}), true);
+
+  auto step = [&](Optimizer optim, Container model) {
+    optim->zero_grad();
+    auto y = model->forward({x})[0].sum();
+    backward(y);
+    optim->step();
+  };
+
+  // Do 2 steps of model1
+  step(optim1, model1);
+  step(optim1, model1);
+
+  // Do 2 steps of model 2 without saving the optimizer
+  step(optim2, model2);
+  step(optim2_2, model2);
+
+  // Do 2 steps of model 3 while saving the optimizer
+  step(optim3, model3);
+  ss.clear();
+  save(ss, optim3);
+  load(ss, optim3_2);
+  step(optim3_2, model3);
+
+  auto param1 = model1->parameters();
+  auto param2 = model2->parameters();
+  auto param3 = model3->parameters();
+  for (auto& p : param1) {
+    auto name = p.first;
+    // Model 1 and 3 should be the same
+    EXPECT(param1[name].norm().toCFloat() == param3[name].norm().toCFloat());
+    EXPECT(param1[name].norm().toCFloat() != param2[name].norm().toCFloat());
+  }
+}

test/cpp/api/test.cpp

@@ -0,0 +1,10 @@
+#include "test.h"
+
+lest::tests & specification() {
+  static lest::tests tests;
+  return tests;
+}
+
+int main( int argc, char * argv[] ) {
+  return lest::run( specification(), argc, argv);
+}

test/cpp/api/test.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "lest.hpp"
+#include <torch/autograd.h>
+
+using namespace autograd;
+
+#define CASE( name ) lest_CASE( specification(), name )
+
+#define CUDA_GUARD if (!hasCuda()) {\
+  std::cerr << "No cuda, skipping test" << std::endl; return;\
+}
+
+extern lest::tests & specification();

third_party/cereal

@@ -0,0 +1 @@
+Subproject commit 51cbda5f30e56c801c07fe3d3aba5d7fb9e6cca4

tools/cpp_build/libtorch/CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
 cmake_policy(VERSION 3.0)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
@@ -155,10 +155,19 @@ set(TORCH_SRCS
   ${TORCH_SRC_DIR}/csrc/jit/type.cpp
   ${TORCH_SRC_DIR}/csrc/jit/interpreter_autograd_function.cpp
   ${TORCH_SRC_DIR}/csrc/Exceptions.cpp
+  ${TORCH_SRC_DIR}/csrc/api/src/detail.cpp
+  ${TORCH_SRC_DIR}/csrc/api/src/containers.cpp
+  ${TORCH_SRC_DIR}/csrc/api/src/optimizers.cpp
   )
 
 add_library(torch SHARED ${TORCH_SRCS})
 
+target_compile_options(torch PRIVATE -Wall -Wextra)
+
+if ($ENV{WERROR})
+  target_compile_options(torch PRIVATE -Werror)
+endif()
+
 target_link_libraries(torch
   ${TORCH_CUDA_LIBRARIES}
   ${ATEN_LIBRARY}
@@ -169,6 +178,10 @@ set(COMMON_INCLUDES
   "${ATEN_INCLUDE_DIR}/TH"
   "${ATEN_BUILD_INCLUDE_DIR}"
   "${ATEN_BUILD_PATH}/src/TH"
+  "${TORCH_SRC_DIR}/csrc/api/"
+  "${TORCH_SRC_DIR}/csrc/api/include"
+  "${TORCH_SRC_DIR}/../third_party/cereal/include" # For cereal/
+  "${TORCH_SRC_DIR}/../"
   "${CMAKE_CURRENT_SOURCE_DIR}"
   "${CUDA_INCLUDE_DIRS}")
 
@@ -193,9 +206,9 @@ install(TARGETS torch
   LIBRARY DESTINATION "${TORCH_INSTALL_LIB_DIR}"
   ARCHIVE DESTINATION "${TORCH_INSTALL_LIB_DIR}")
 
-set(TORCH_TEST_SRCS ${TORCH_SRC_DIR}/csrc/jit/test_jit.cpp)
+# JIT Tests. TODO: Put into test/cpp/jit folder
 
-add_executable(test_jit ${TORCH_TEST_SRCS})
+add_executable(test_jit ${TORCH_SRC_DIR}/csrc/jit/test_jit.cpp)
 
 target_link_libraries(test_jit torch)
 
@@ -204,7 +217,19 @@ target_include_directories(test_jit PUBLIC
   "${TORCH_SRC_DIR}/../third_party/catch/single_include"
   "${COMMON_INCLUDES}")
 
-install(TARGETS test_jit
+# API Tests
-  RUNTIME DESTINATION "${TORCH_INSTALL_BIN_DIR}"
+
-  LIBRARY DESTINATION "${TORCH_INSTALL_LIB_DIR}"
+set(TORCH_API_TEST_DIR "${TORCH_SRC_DIR}/../test/cpp/api")
-  ARCHIVE DESTINATION "${TORCH_INSTALL_LIB_DIR}")
+
+add_executable(test_api
+  ${TORCH_API_TEST_DIR}/test.cpp
+  ${TORCH_API_TEST_DIR}/container_t.cpp
+  ${TORCH_API_TEST_DIR}/misc_t.cpp
+  ${TORCH_API_TEST_DIR}/rnn_t.cpp
+  ${TORCH_API_TEST_DIR}/integration_t.cpp
+  ${TORCH_API_TEST_DIR}/optim_t.cpp
+  ${TORCH_API_TEST_DIR}/serialization_t.cpp
+)
+
+target_compile_options(test_api PRIVATE -Dlest_FEATURE_AUTO_REGISTER=1)
+target_link_libraries(test_api torch)

tools/download_mnist.py

@@ -0,0 +1,81 @@
+from __future__ import division
+from __future__ import print_function
+
+import argparse
+import gzip
+import os
+import sys
+import urllib
+
+try:
+    from urllib.error import URLError
+    from urllib.request import urlretrieve
+except ImportError:
+    from urllib2 import URLError
+    from urllib import urlretrieve
+
+RESOURCES = [
+    'train-images-idx3-ubyte.gz',
+    'train-labels-idx1-ubyte.gz',
+    't10k-images-idx3-ubyte.gz',
+    't10k-labels-idx1-ubyte.gz',
+]
+
+
+def report_download_progress(chunk_number, chunk_size, file_size):
+    if file_size != -1:
+        percent = min(1, (chunk_number * chunk_size) / file_size)
+        bar = '#' * int(64 * percent)
+        sys.stdout.write('\r0% |{:<64}| {}%'.format(bar, int(percent * 100)))
+
+
+def download(destination_path, url):
+    if os.path.exists(destination_path):
+        print('{} already exists, skipping ...'.format(destination_path))
+    else:
+        print('Downloading {} ...'.format(url))
+        try:
+            urlretrieve(
+                url, destination_path, reporthook=report_download_progress)
+        except URLError:
+            raise RuntimeError('Error downloading resource!')
+        finally:
+            # Just a newline.
+            print()
+
+
+def unzip(zipped_path):
+    unzipped_path = os.path.splitext(zipped_path)[0]
+    if os.path.exists(unzipped_path):
+        print('{} already exists, skipping ... '.format(unzipped_path))
+        return
+    with gzip.open(zipped_path, 'rb') as zipped_file:
+        with open(unzipped_path, 'wb') as unzipped_file:
+            unzipped_file.write(zipped_file.read())
+            print('Unzipped {} ...'.format(zipped_path))
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description='Download the MNIST dataset from the internet')
+    parser.add_argument(
+        '-d', '--destination', default='.', help='Destination directory')
+    options = parser.parse_args()
+
+    if not os.path.exists(options.destination):
+        os.makedirs(options.destination)
+
+    try:
+        for resource in RESOURCES:
+            path = os.path.join(options.destination, resource)
+            url = 'http://yann.lecun.com/exdb/mnist/{}'.format(resource)
+            download(path, url)
+            unzip(path)
+    except KeyboardInterrupt:
+        print('Interrupted')
+
+    print('Done')
+
+
+if __name__ == '__main__':
+    main()

torch/csrc/api/README.md

@@ -0,0 +1,50 @@
+# AUTOGRADPP
+
+This is an experimental C++ frontend to pytorch's C++ backend. Use at your own
+risk.
+
+How to build:
+```
+git submodule update --init --recursive
+
+cd pytorch
+# On Linux:
+python setup.py build
+# On macOS (may need to prefix with `MACOSX_DEPLOYMENT_TARGET=10.9 CC=clang CXX=clang++` when using anaconda)
+LDSHARED="cc -dynamiclib -undefined dynamic_lookup" python setup.py build
+
+cd ..; mkdir -p build; cd build
+cmake .. -DPYTHON_EXECUTABLE:FILEPATH=$(which python)  # helpful if you use anaconda
+make -j
+```
+
+# Stuff
+
+- Check out the [MNIST example](https://github.com/ebetica/autogradpp/blob/eee977ddd377c484af5fce09ae8676410bb6fcce/tests/integration_t.cpp#L320-L355),
+which tries to replicate PyTorch's MNIST model + training loop
+- The principled way to write a model is probably something like 
+```
+AUTOGRAD_CONTAINER_CLASS(MyModel) {
+  // This does a 2D convolution, followed by global sum pooling, followed by a linear.
+ public:
+  void initialize_containers() override {
+    myConv_ = add(Conv2d(1, 50, 3, 3).stride(2).make(), "conv");
+    myLinear_ = add(Linear(50, 1).make(), "linear");
+  }
+  variable_list forward(variable_list x) override {
+    auto v = myConv_->forward(x);
+    v = v.mean(-1).mean(-1);
+    return myLinear_.forward({v});
+  }
+ private:
+  Container myLinear_;
+  Container myConv_;
+}
+```
+
+Some things are not implemented:
+- SGD, Adagrad, RMSprop, and Adam are the only optimizers implemented
+- Bidirectional, batch first, and PackedSequence are not implemented for LSTMs
+- Sparse Tensors might work but are very untested
+
+Otherwise, lots of other things work. There may be breaking API changes.

torch/csrc/api/include/torch/autograd.h

@@ -0,0 +1,4 @@
+#pragma once
+#include "torch/containers.h"
+#include "torch/optimizers.h"
+#include "torch/serialization.h"

torch/csrc/api/include/torch/containers.h

@@ -0,0 +1,446 @@
+#pragma once
+
+#include "detail.h"
+
+#include "torch/csrc/autograd/variable.h"
+
+#define AUTOGRAD_CONTAINER_CLASS(Type) \
+  class Type : public autograd::Container_CRTP<Type>
+
+namespace autograd {
+class ContainerImpl {
+ public:
+  // Only construct parameters in initialize_parameters, and
+  // containers in initialize_containers. Most of the time, the containers are
+  // the only thing you need to add.
+  // You are guaranteed that containers are added before parameters.
+  virtual void initialize_containers(){};
+  virtual void initialize_parameters(){};
+  virtual void reset_parameters(){};
+
+  virtual variable_list forward(variable_list) = 0;
+  virtual Container clone() const = 0;
+
+  std::map<std::string, Variable> parameters() const;
+  Variable& param(std::string const&);
+
+  virtual void cuda();
+  virtual void cpu();
+  void train();
+  void eval();
+
+  at::Type& DefaultTensor(at::ScalarType s);
+
+  std::unordered_map<std::string, Container> children_;
+  std::unordered_map<std::string, Variable> params_;
+  bool cuda_ = false;
+  bool train_ = true;
+
+  template <class Archive>
+  void save(Archive& ar) const {
+    auto params = parameters();
+    std::size_t size = params.size();
+    ar(size);
+    for (auto& p : params) {
+      ar(p.first, p.second);
+    }
+  }
+
+  template <class Archive>
+  void load(Archive& ar) {
+    auto params = parameters();
+    std::size_t size;
+    ar(size);
+    std::string name;
+    for (std::size_t i = 0; i < size; i++) {
+      ar(name);
+      ar(params[name]);
+    }
+  }
+
+ protected:
+  Container add(Container, std::string const&);
+  // Be careful when registering Tensors that are not variables
+  Variable& add(Variable, std::string const&);
+};
+
+template <class Derived>
+class Container_CRTP : public ContainerImpl {
+ public:
+  std::shared_ptr<Derived> make() const {
+    auto ptr = std::make_shared<Derived>(*static_cast<const Derived*>(this));
+    ptr->initialize_containers();
+    ptr->initialize_parameters();
+    ptr->reset_parameters();
+    return ptr;
+  }
+
+  Container clone() const override {
+    auto ptr = std::make_shared<Derived>(*static_cast<const Derived*>(this));
+    ptr->children_.clear();
+    ptr->params_.clear();
+    ptr->initialize_containers();
+    ptr->initialize_parameters();
+    auto newParams = ptr->parameters();
+    for (auto& param : parameters()) {
+      newParams[param.first].data().copy_(param.second.data());
+    }
+    if (cuda_) {
+      ptr->cuda();
+    } else {
+      ptr->cpu();
+    }
+    return ptr;
+  }
+};
+
+template <class Derived>
+class ContainerListImpl : public Container_CRTP<Derived> {
+  // Lets you use a container like a vector without making a new class,
+  // just for simple implementations
+ public:
+  virtual variable_list forward(variable_list) override {
+    throw std::runtime_error(
+        "ContainerList has no forward, maybe you"
+        " wanted to subclass and override this function?");
+  }
+
+  Container add(Container m) {
+    return append(m).children_.back();
+  }
+
+  ContainerListImpl<Derived>& append(Container m) {
+    children_.push_back(m);
+    ContainerImpl::add(children_.back(), std::to_string(size() - 1));
+    return *this;
+  }
+
+  Container& operator[](int index) {
+    return children_[index];
+  }
+
+  int size() {
+    return children_.size();
+  }
+
+  std::vector<Container>::iterator begin() {
+    return children_.begin();
+  }
+
+  std::vector<Container>::iterator end() {
+    return children_.end();
+  }
+
+  std::vector<Container> children_;
+};
+
+class ContainerList : public ContainerListImpl<ContainerList> {};
+
+class Sequential : public ContainerListImpl<Sequential> {
+  // Mimics nn.Sequential from pytorch.
+ public:
+  variable_list forward(variable_list input) override {
+    for (auto& container : children_) {
+      input = container->forward(input);
+    }
+    return input;
+  }
+
+  Container add(Container m, std::string name = "") {
+    return append(m, name).children_.back();
+  }
+
+  Sequential& append(Container m, std::string name = "") {
+    if (name == "") {
+      name = std::to_string(size());
+    }
+    children_.push_back(m);
+    ContainerImpl::add(children_.back(), name);
+    return *this;
+  }
+};
+
+AUTOGRAD_CONTAINER_CLASS(SimpleContainer) {
+  // Lets you use a container without making a new class,
+  // for experimental implementations
+ public:
+  virtual variable_list forward(variable_list) override {
+    throw std::runtime_error(
+        "SimpleContainer has no forward, maybe you"
+        " wanted to subclass and override this function?");
+  }
+  using ContainerImpl::add;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Functional) {
+  // Lets you create a container from a function, designed for use in
+  // Sequential.
+ public:
+  Functional(std::function<variable_list(variable_list)> fun) : fun_(fun){};
+  Functional(std::function<Variable(Variable)> fun)
+      : fun_([fun](variable_list input) {
+          return variable_list({fun(input[0])});
+        }){};
+
+  variable_list forward(variable_list input) override {
+    return fun_(input);
+  };
+
+  std::function<variable_list(variable_list)> fun_;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Linear) {
+ public:
+  Linear(uint32_t nin, uint32_t nout) : nin(nin), nout(nout) {}
+
+  variable_list forward(variable_list) override;
+  void reset_parameters() override;
+  void initialize_parameters() override;
+  AUTOGRAD_KWARG(Linear, bool, no_bias, false, true);
+
+  Variable weight, bias;
+  uint32_t nin, nout;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Embedding) {
+ public:
+  Embedding(uint32_t num_embeddings, uint32_t embedding_dim)
+      : num_embeddings(num_embeddings), embedding_dim(embedding_dim) {}
+
+  variable_list forward(variable_list) override;
+  void reset_parameters() override;
+  void initialize_parameters() override;
+
+  Variable weight;
+  uint32_t num_embeddings, embedding_dim;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Conv) {
+ private:
+  Conv(uint32_t Nd, uint32_t in_chan, uint32_t out_chan)
+      : Nd_(Nd),
+        in_channels_(in_chan),
+        out_channels_(out_chan),
+        stride_(makeTup(1, 1)),
+        padding_(makeTup(0)),
+        dilation_(makeTup(1, 1)),
+        dilated_(false),
+        output_padding_(makeTup(0)) {}
+
+ public:
+  Conv(uint32_t Nd, uint32_t in_chan, uint32_t out_chan, int ks)
+      : Conv(Nd, in_chan, out_chan) {
+    ks_ = makeTup(ks, 1);
+  }
+
+  Conv(uint32_t Nd, uint32_t in_chan, uint32_t out_chan, IntVec ks)
+      : Conv(Nd, in_chan, out_chan) {
+    ks_ = makeTup(ks);
+  }
+
+  void reset_parameters() override;
+  variable_list forward(variable_list) override;
+  void initialize_parameters() override;
+
+  template <typename T>
+  Conv& stride(T s) {
+    stride_ = makeTup(s, 1);
+    return *this;
+  }
+  template <typename T>
+  Conv& padding(T s) {
+    padding_ = makeTup(s);
+    return *this;
+  }
+  template <typename T>
+  Conv& dilation(T s) {
+    dilation_ = makeTup(s, 1);
+    return *this;
+  }
+  template <typename T>
+  Conv& output_padding(T s) {
+    output_padding_ = makeTup(s);
+    return *this;
+  }
+
+  AUTOGRAD_KWARG(Conv, bool, transposed, false, true)
+  AUTOGRAD_KWARG(Conv, bool, no_bias, false, true)
+  AUTOGRAD_KWARG(Conv, int, groups, 1, 1)
+
+  Variable weight, bias;
+  uint32_t Nd_;
+  uint32_t in_channels_;
+  uint32_t out_channels_;
+  IntVec ks_;
+  IntVec stride_;
+  IntVec padding_;
+  IntVec dilation_;
+  bool dilated_;
+  IntVec output_padding_;
+
+ protected:
+  IntVec makeTup(int x, int def = 0) {
+    IntVec ret;
+    if (Nd_ == 1) {
+      ret.push_back(x);
+      ret.push_back(def);
+    } else {
+      for (auto i = 0U; i < Nd_; i++)
+        ret.push_back(x);
+    }
+    return ret;
+  }
+  IntVec makeTup(IntVec x) {
+    return x;
+  }
+};
+
+class Conv1d : public Conv {
+ public:
+  Conv1d(uint32_t i, uint32_t o, int ks) : Conv(1, i, o, ks) {}
+  Conv1d(uint32_t i, uint32_t o, IntVec ks) : Conv(1, i, o, ks) {}
+};
+
+class Conv2d : public Conv {
+ public:
+  Conv2d(uint32_t i, uint32_t o, int ks) : Conv(2, i, o, ks) {}
+  Conv2d(uint32_t i, uint32_t o, IntVec ks) : Conv(2, i, o, ks) {}
+};
+
+class Conv3d : public Conv {
+ public:
+  Conv3d(uint32_t i, uint32_t o, int ks) : Conv(3, i, o, ks) {}
+  Conv3d(uint32_t i, uint32_t o, IntVec ks) : Conv(3, i, o, ks) {}
+};
+
+AUTOGRAD_CONTAINER_CLASS(BatchNorm) {
+ public:
+  BatchNorm(uint32_t num_features) : num_features_(num_features) {}
+
+  AUTOGRAD_KWARG(BatchNorm, double, eps, 1e-5, 1e-5)
+  AUTOGRAD_KWARG(BatchNorm, double, momentum, 0.1, 0.1)
+  AUTOGRAD_KWARG(BatchNorm, bool, affine, true, true)
+  AUTOGRAD_KWARG(BatchNorm, bool, stateful, false, true)
+
+  void reset_parameters() override;
+  variable_list forward(variable_list) override;
+  void initialize_parameters() override;
+
+  Variable weight;
+  Variable bias;
+  Variable running_mean;
+  Variable running_var;
+
+ protected:
+  uint32_t num_features_;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Dropout) {
+ public:
+  Dropout(double p = 0.5) : p_(p) {
+    assert(p < 1 && p >= 0);
+  }
+  variable_list forward(variable_list) override;
+
+ protected:
+  double p_;
+};
+
+AUTOGRAD_CONTAINER_CLASS(Dropout2d) {
+ public:
+  Dropout2d(double p = 0.5) : p_(p) {
+    assert(p < 1 && p >= 0);
+  }
+  variable_list forward(variable_list) override;
+
+ protected:
+  double p_;
+};
+
+template <typename Derived>
+class RNNBase : public Container_CRTP<Derived> {
+ public:
+  // These must line up with the CUDNN mode codes
+  enum RNNMode : int64_t { RNN_RELU = 0, RNN_TANH = 1, LSTM = 2, GRU = 3 };
+  RNNBase(uint32_t input_size, uint32_t hidden_size)
+      : input_size_(input_size), hidden_size_(hidden_size) {}
+
+  AUTOGRAD_KWARG(RNNBase, RNNMode, mode, RNNMode::LSTM, RNNMode::LSTM)
+  AUTOGRAD_KWARG(RNNBase, uint32_t, nlayers, 1, 1);
+  AUTOGRAD_KWARG(RNNBase, bool, no_bias, false, true)
+  AUTOGRAD_KWARG(RNNBase, float, dropout, 0, 0)
+
+  bool flatten_parameters(); // Flatten for cudnn
+
+  variable_list forward(variable_list) override;
+  void initialize_containers() override;
+  void reset_parameters() override;
+
+  void cpu() override;
+  void cuda() override;
+
+  std::vector<Container> i2h;
+  std::vector<Container> h2h;
+
+ protected:
+  uint32_t input_size_;
+  uint32_t hidden_size_;
+  uint32_t gate_size_;
+  // This is copied from pytorch, to determine whether weights are flat for
+  // the fast CUDNN route. Otherwise, we have to use non flattened weights,
+  // which
+  // are much slower.
+  // https://github.com/pytorch/pytorch/blob/1848cad10802db9fa0aa066d9de195958120d863/torch/nn/modules/rnn.py#L159-L165
+  // TODO Actually since we are in C++ we can probably just actually check if
+  // the parameters are flat, instead of relying on data pointers and stuff.
+  std::vector<void*> data_ptrs_;
+  Variable flat_weight_;
+  Container dropout_module;
+
+  variable_list CUDNN_forward(variable_list);
+  variable_list autograd_forward(variable_list);
+
+  variable_list cell_forward(variable_list, int);
+  variable_list LSTM_cell_forward(variable_list, int);
+  variable_list GRU_cell_forward(variable_list, int);
+  variable_list RNN_RELU_cell_forward(variable_list, int);
+  variable_list RNN_TANH_cell_forward(variable_list, int);
+};
+
+// We must instantiate these templates so we can put implementations in the .cpp
+class LSTM;
+template class RNNBase<LSTM>;
+class LSTM : public RNNBase<LSTM> {
+ public:
+  LSTM(uint32_t inp_size, uint32_t hid_size) : RNNBase(inp_size, hid_size) {
+    mode_ = RNNBase::RNNMode::LSTM;
+  }
+};
+
+class GRU;
+template class RNNBase<GRU>;
+class GRU : public RNNBase<GRU> {
+ public:
+  GRU(uint32_t inp_size, uint32_t hid_size) : RNNBase(inp_size, hid_size) {
+    mode_ = RNNBase::RNNMode::GRU;
+  }
+};
+
+class RNN;
+template class RNNBase<RNN>;
+class RNN : public RNNBase<RNN> {
+ public:
+  enum Mode { Tanh, Relu };
+  RNN(uint32_t inp_size, uint32_t hid_size, Mode mode = Mode::Tanh)
+      : RNNBase(inp_size, hid_size) {
+    if (mode == Mode::Tanh) {
+      mode_ = RNNBase::RNNMode::RNN_TANH;
+    } else if (mode == Mode::Relu) {
+      mode_ = RNNBase::RNNMode::RNN_RELU;
+    } else {
+      throw std::runtime_error("RNN Mode not supported");
+    }
+  }
+};
+
+} // namespace autograd

torch/csrc/api/include/torch/detail.h

@@ -0,0 +1,70 @@
+#pragma once
+
+#include <map>
+#include <memory>
+
+#include "torch/csrc/autograd/engine.h"
+#include "torch/csrc/autograd/grad_mode.h"
+
+// for AutoGPU. Usage:
+//   AutoGPU gpu_raii(1);
+// While this object is in scope, all of your GPU tensors will go to GPU 1
+#include "torch/csrc/utils/auto_gpu.h"
+
+#define AUTOGRAD_OPTIMIZER_CLASS(Type) \
+  class Type : public autograd::Optimizer_CRTP<Type>
+#define AUTOGRAD_KWARG(CLS, TYP, NAME, DEFAULT, OPTION) \
+  TYP NAME##_ = DEFAULT;                                \
+  CLS& NAME(TYP x = OPTION) {                           \
+    NAME##_ = x;                                        \
+    return *this;                                       \
+  }
+
+namespace {
+namespace tag = torch::autograd;
+using IntVec = decltype(std::declval<at::IntList>().vec());
+} // namespace
+
+namespace autograd {
+namespace detail {
+extern tag::Engine engine;
+}
+
+class ContainerImpl;
+class OptimizerImpl;
+using Variable = tag::Variable;
+using variable_list = tag::variable_list;
+using Tensor = at::Tensor;
+using Container = std::shared_ptr<ContainerImpl>;
+using Optimizer = std::shared_ptr<OptimizerImpl>;
+
+void backward(Tensor loss, bool keep_graph = false);
+
+inline Variable Var(at::Tensor data, bool requires_grad = true) {
+  return tag::make_variable(data, requires_grad);
+}
+
+// This is thread local!!!
+inline void set_grad_enabled(bool val = true) {
+  tag::GradMode::set_enabled(val);
+}
+
+// RAII thread local lock that stops future execution from building gradients
+class no_grad_guard {
+ public:
+  no_grad_guard() {
+    tag::GradMode::set_enabled(false);
+  }
+
+  ~no_grad_guard() {
+    tag::GradMode::set_enabled(true);
+  }
+};
+
+void setSeed(uint64_t seed);
+
+int getNumGPUs();
+bool hasCuda();
+bool hasCudnn();
+
+} // namespace autograd

torch/csrc/api/include/torch/optimizers.h

@@ -0,0 +1,139 @@
+#pragma once
+
+#include "torch/containers.h"
+#include "torch/detail.h"
+
+#include "cereal/access.hpp"
+#include "cereal/cereal.hpp"
+
+namespace autograd {
+class OptimizerImpl {
+ public:
+  OptimizerImpl(Container model) : model_(model) {}
+  virtual void init_state() {}
+  virtual void step() = 0;
+  void zero_grad();
+
+  void set_model(Container model);
+
+ protected:
+  OptimizerImpl() {}
+  Container model_;
+};
+
+template <class Derived>
+class Optimizer_CRTP : public OptimizerImpl {
+ public:
+  Optimizer_CRTP(Container model) : OptimizerImpl(model) {}
+  std::shared_ptr<Derived> make() const {
+    auto ptr = std::make_shared<Derived>(*static_cast<const Derived*>(this));
+    ptr->init_state();
+    return ptr;
+  }
+
+ protected:
+  Optimizer_CRTP() {}
+};
+
+AUTOGRAD_OPTIMIZER_CLASS(SGD) {
+ public:
+  SGD(Container model, double lr) : Optimizer_CRTP(model), lr_(lr) {}
+  AUTOGRAD_KWARG(SGD, double, momentum, 0, 0);
+  AUTOGRAD_KWARG(SGD, double, dampening, 0, 0);
+  AUTOGRAD_KWARG(SGD, double, weight_decay, 0, 0);
+  AUTOGRAD_KWARG(SGD, bool, nesterov, false, true);
+  double lr_;
+  void step() override;
+  void init_state() override;
+
+  template <class Archive>
+  void serialize(Archive & ar) {
+    ar(CEREAL_NVP(momentum_buffers_));
+  }
+
+ private:
+  friend class cereal::access;
+  SGD() {}
+  std::unordered_map<std::string, at::Tensor> momentum_buffers_;
+};
+
+AUTOGRAD_OPTIMIZER_CLASS(Adagrad) {
+ public:
+  Adagrad(Container model, double lr) : Optimizer_CRTP(model), lr_(lr) {}
+  AUTOGRAD_KWARG(Adagrad, double, lr_decay, 0, 0);
+  AUTOGRAD_KWARG(Adagrad, double, weight_decay, 0, 0);
+  double lr_;
+  void step() override;
+  void init_state() override;
+
+  template <class Archive>
+  void serialize(Archive & ar) {
+    ar(CEREAL_NVP(sum_));
+    ar(CEREAL_NVP(step_));
+  }
+
+ private:
+  friend class cereal::access;
+  Adagrad() {}
+  std::unordered_map<std::string, at::Tensor> sum_;
+  std::unordered_map<std::string, double> step_;
+};
+
+AUTOGRAD_OPTIMIZER_CLASS(RMSprop) {
+ public:
+  RMSprop(Container model, double lr) : Optimizer_CRTP(model), lr_(lr) {}
+  AUTOGRAD_KWARG(RMSprop, double, alpha, 0.99, 0.99);
+  AUTOGRAD_KWARG(RMSprop, double, eps, 1e-8, 1e-8);
+  AUTOGRAD_KWARG(RMSprop, double, weight_decay, 0, 0);
+  AUTOGRAD_KWARG(RMSprop, double, momentum, 0, 0);
+  AUTOGRAD_KWARG(RMSprop, bool, centered, false, true);
+
+  double lr_;
+  void step() override;
+  void init_state() override;
+
+  template <class Archive>
+  void serialize(Archive & ar) {
+    ar(CEREAL_NVP(square_avg_buffer_));
+    ar(CEREAL_NVP(momentum_buffer_));
+    ar(CEREAL_NVP(grad_avg_buffer_));
+  }
+
+ private:
+  friend class cereal::access;
+  RMSprop() {}
+  std::unordered_map<std::string, at::Tensor> square_avg_buffer_;
+  std::unordered_map<std::string, at::Tensor> momentum_buffer_;
+  std::unordered_map<std::string, at::Tensor> grad_avg_buffer_;
+};
+
+AUTOGRAD_OPTIMIZER_CLASS(Adam) {
+ public:
+  Adam(Container model, double lr) : Optimizer_CRTP(model), lr_(lr) {}
+  AUTOGRAD_KWARG(Adam, double, beta1, 0.9, 0.9);
+  AUTOGRAD_KWARG(Adam, double, beta2, 0.999, 0.999);
+  AUTOGRAD_KWARG(Adam, double, weight_decay, 0, 0);
+  AUTOGRAD_KWARG(Adam, double, eps, 1e-8, 1e-8);
+  AUTOGRAD_KWARG(Adam, bool, amsgrad, false, true);
+  double lr_;
+  void step() override;
+  void init_state() override;
+
+  template <class Archive>
+  void serialize(Archive & ar) {
+    ar(CEREAL_NVP(step_buffer_),
+       CEREAL_NVP(exp_avg_buffer_),
+       CEREAL_NVP(exp_avg_sq_buffer_),
+       CEREAL_NVP(max_exp_avg_sq_buffer_));
+  }
+
+ private:
+  friend class cereal::access;
+  Adam() {}
+  std::unordered_map<std::string, int> step_buffer_;
+  std::unordered_map<std::string, at::Tensor> exp_avg_buffer_;
+  std::unordered_map<std::string, at::Tensor> exp_avg_sq_buffer_;
+  std::unordered_map<std::string, at::Tensor> max_exp_avg_sq_buffer_;
+};
+
+} // namespace autograd

torch/csrc/api/include/torch/serialization.h

@@ -0,0 +1,236 @@
+#pragma once
+
+#include <fstream>
+
+#include "cereal/archives/binary.hpp"
+#include "cereal/types/polymorphic.hpp"
+
+#include "cereal/types/string.hpp"
+#include "cereal/types/unordered_map.hpp"
+#include "cereal/types/vector.hpp"
+
+namespace autograd {
+
+// Some convenience functions for saving and loading
+template <typename T>
+void save(std::ostream& stream, T const& obj) {
+  cereal::BinaryOutputArchive archive(stream);
+  archive(*obj);
+}
+template <typename T>
+void load(std::istream& stream, T& obj) {
+  cereal::BinaryInputArchive archive(stream);
+  archive(*obj);
+}
+template <typename T>
+void save(std::ostream& stream, T const* obj) {
+  cereal::BinaryOutputArchive archive(stream);
+  archive(*obj);
+}
+template <typename T>
+void load(std::istream& stream, T* obj) {
+  cereal::BinaryInputArchive archive(stream);
+  archive(*obj);
+}
+template <typename T>
+void save(std::string const& path, T const& obj) {
+  std::ofstream os(path, std::ios::binary);
+  autograd::save(os, obj);
+}
+template <typename T>
+void load(std::string const& path, T& obj) {
+  std::ifstream is(path, std::ios::binary);
+  autograd::load(is, obj);
+}
+
+namespace detail {
+
+// We use our own hard-coded type<->id mapping so that serialization is robust
+// wrt changes in ATen; see e.g. https://git.io/vxd6R
+// The mapping is consistent with the ScalarType enum as of pytorch version
+// v0.1.11-7675-ge94c67e.
+inline int32_t scalarTypeId(at::ScalarType type) {
+  switch (type) {
+    case at::ScalarType::Byte: return 0;
+    case at::ScalarType::Char: return 1;
+    case at::ScalarType::Short: return 2;
+    case at::ScalarType::Int: return 3;
+    case at::ScalarType::Long: return 4;
+    case at::ScalarType::Half: return 5;
+    case at::ScalarType::Float: return 6;
+    case at::ScalarType::Double: return 7;
+    case at::ScalarType::Undefined: return 8;
+    default:
+      throw std::runtime_error(
+          "Unknown scalar type: " + std::to_string(static_cast<int>(type)));
+  }
+}
+
+inline at::ScalarType scalarTypeFromId(int32_t id) {
+  switch (id) {
+    case 0: return at::ScalarType::Byte;
+    case 1: return at::ScalarType::Char;
+    case 2: return at::ScalarType::Short;
+    case 3: return at::ScalarType::Int;
+    case 4: return at::ScalarType::Long;
+    case 5: return at::ScalarType::Half;
+    case 6: return at::ScalarType::Float;
+    case 7: return at::ScalarType::Double;
+    case 8: return at::ScalarType::Undefined;
+    default:
+      throw std::runtime_error("Unknown scalar type id: " + std::to_string(id));
+  }
+}
+
+inline int32_t backendId(at::Backend backend) {
+  switch (backend) {
+    case at::Backend::CPU: return 0;
+    case at::Backend::CUDA: return 1;
+    case at::Backend::SparseCPU: return 2;
+    case at::Backend::SparseCUDA: return 3;
+    case at::Backend::Undefined: return 4;
+    default:
+      throw std::runtime_error(
+          "Unknown backend: " + std::to_string(static_cast<int>(backend)));
+  }
+}
+
+inline at::Backend backendFromId(int32_t id) {
+  switch (id) {
+    case 0: return at::Backend::CPU;
+    case 1: return at::Backend::CUDA;
+    case 2: return at::Backend::SparseCPU;
+    case 3: return at::Backend::SparseCUDA;
+    case 4: return at::Backend::Undefined;
+    default:
+      throw std::runtime_error("Unknown backend id: " + std::to_string(id));
+  }
+}
+
+} // namespace detail
+} // namespace autograd
+
+// This is super ugly and I don't know how to simplify it
+CEREAL_REGISTER_TYPE(autograd::SGD);
+CEREAL_REGISTER_POLYMORPHIC_RELATION(autograd::OptimizerImpl, autograd::SGD);
+CEREAL_REGISTER_TYPE(autograd::Adagrad);
+CEREAL_REGISTER_POLYMORPHIC_RELATION(
+    autograd::OptimizerImpl,
+    autograd::Adagrad);
+CEREAL_REGISTER_TYPE(autograd::RMSprop);
+CEREAL_REGISTER_POLYMORPHIC_RELATION(
+    autograd::OptimizerImpl,
+    autograd::RMSprop);
+CEREAL_REGISTER_TYPE(autograd::Adam);
+CEREAL_REGISTER_POLYMORPHIC_RELATION(autograd::OptimizerImpl, autograd::Adam);
+
+namespace cereal {
+
+namespace agimpl {
+
+template <class Archive>
+void saveBinary(Archive& archive, void const* data, std::size_t size) {
+  // In general, there's no direct `saveBinary`-like method on archives
+  std::vector<char> v(
+      static_cast<char const*>(data), static_cast<char const*>(data) + size);
+  archive(v);
+}
+template <>
+inline void
+saveBinary(BinaryOutputArchive& archive, void const* data, std::size_t size) {
+  // Writes to output stream without extra copy
+  archive.saveBinary(data, size);
+}
+
+template <class Archive>
+void loadBinary(Archive& archive, void* data, std::size_t size) {
+  // In general, there's no direct `loadBinary`-like method on archives
+  std::vector<char> v(size);
+  archive(v);
+  std::memcpy(data, v.data(), size);
+}
+template <>
+inline void
+loadBinary(BinaryInputArchive& archive, void* data, std::size_t size) {
+  // Read from input stream without extra copy
+  archive.loadBinary(data, size);
+}
+
+} // namespace agimpl
+
+// Gradients will not be saved for variables
+template <class Archive>
+void save(Archive& archive, at::Tensor const& tensor) {
+  if (!tensor.defined()) {
+    int32_t typeId = ::autograd::detail::scalarTypeId(at::ScalarType::Undefined);
+    archive(CEREAL_NVP(typeId));
+    return;
+  } else {
+    int32_t typeId = ::autograd::detail::scalarTypeId(tensor.type().scalarType());
+    archive(CEREAL_NVP(typeId));
+  }
+  auto sizes = std::vector<int64_t>();
+  auto buf = std::vector<uint8_t>();
+  for (auto s : tensor.sizes()) {
+    sizes.push_back(s);
+  }
+  auto contig = tensor.toBackend(at::kCPU).contiguous();
+  int32_t backend = ::autograd::detail::backendId(tensor.type().backend());
+
+  archive(CEREAL_NVP(backend), CEREAL_NVP(sizes));
+  agimpl::saveBinary(
+      archive,
+      contig.data_ptr(),
+      tensor.numel() * tensor.type().elementSizeInBytes());
+}
+
+/**
+ * We follow these rules for loading:
+ * 1. If tensor is defined, and the same ScalarType as the saved tensor,
+ *    then we simply copy the data into the tensor, with resizing.
+ * 2. Otherwise, overwrite the provided tensor with the right type and backend
+ **/
+template <class Archive>
+void load(Archive& archive, at::Tensor& tensor) {
+  at::ScalarType type;
+  int32_t typeId;
+  archive(CEREAL_NVP(typeId));
+  type = ::autograd::detail::scalarTypeFromId(typeId);
+  if (type == at::ScalarType::Undefined) {
+    tensor = at::Tensor();
+    return;
+  }
+
+  int32_t backendId;
+  auto sizes = std::vector<int64_t>();
+  auto buf = std::vector<uint8_t>();
+  archive(CEREAL_NVP(backendId), CEREAL_NVP(sizes));
+
+  at::Backend backend = ::autograd::detail::backendFromId(backendId);
+  if (!tensor.defined() || tensor.type().scalarType() != type) {
+    tensor = at::getType(backend, type).tensor();
+  }
+  tensor.resize_(sizes);
+
+  if (tensor.type().is_cuda()) {
+    // should actually use cudamemcpy probably
+    auto cputensor = at::CPU(tensor.type().scalarType()).tensor(sizes);
+    agimpl::loadBinary(
+        archive,
+        cputensor.data_ptr(),
+        cputensor.numel() * cputensor.type().elementSizeInBytes());
+    tensor.copy_(cputensor);
+  } else {
+    agimpl::loadBinary(
+        archive,
+        tensor.data_ptr(),
+        tensor.numel() * tensor.type().elementSizeInBytes());
+  }
+}
+
+template <class Archive>
+void load(Archive& archive, tag::Variable& var) {
+  load(archive, var.data());
+}
+
+} // namespace cereal

torch/csrc/api/src/containers.cpp

@@ -0,0 +1,633 @@
+#include "torch/containers.h"
+
+namespace autograd {
+std::map<std::string, Variable> ContainerImpl::parameters() const {
+  std::map<std::string, Variable> ret;
+  for (auto pair : children_) {
+    auto& name = pair.first;
+    auto& child = pair.second;
+    for (auto& p : child->parameters()) {
+      ret[name + "." + p.first] = p.second;
+    }
+  }
+  for (auto pair : params_) {
+    ret[pair.first] = pair.second;
+  }
+  return ret;
+}
+
+Variable& ContainerImpl::param(std::string const& name) {
+  ContainerImpl* container = this;
+  auto begin = 0;
+  while (true) {
+    auto dot_pos = name.find('.', begin);
+    if (dot_pos == std::string::npos) {
+      break;
+    }
+
+    auto child_name = name.substr(begin, dot_pos - begin);
+    auto it = container->children_.find(child_name);
+    if (it == container->children_.end()) {
+      throw std::runtime_error("No such child: " + child_name);
+    }
+
+    container = it->second.get();
+    begin = dot_pos + 1; // Skip the dot
+  }
+
+  auto param_name = name.substr(begin);
+  auto it = container->params_.find(param_name);
+  if (it == params_.end()) {
+    throw std::runtime_error("No such param: " + param_name);
+  }
+  return it->second;
+}
+
+void ContainerImpl::cuda() {
+  for (auto& pair : children_) {
+    pair.second->cuda();
+  }
+  cuda_ = true;
+  auto copied = params_;
+  params_.clear();
+  initialize_parameters();
+  for (auto pair : params_) {
+    pair.second.data().copy_(copied[pair.first].data());
+  }
+};
+
+void ContainerImpl::cpu() {
+  for (auto& pair : children_) {
+    pair.second->cpu();
+  }
+  cuda_ = false;
+  auto copied = params_;
+  params_.clear();
+  initialize_parameters();
+  for (auto pair : params_) {
+    pair.second.data().copy_(copied[pair.first].data());
+  }
+};
+
+void ContainerImpl::train() {
+  for (auto& pair : children_) {
+    pair.second->train();
+  }
+  train_ = true;
+}
+
+void ContainerImpl::eval() {
+  for (auto& pair : children_) {
+    pair.second->eval();
+  }
+  train_ = false;
+}
+
+Container ContainerImpl::add(Container m, std::string const& name) {
+  if (this->children_.find(name) != this->children_.end()) {
+    throw std::runtime_error("Trying to add container that already exists");
+  }
+  if (std::find(name.begin(), name.end(), '.') != name.end()) {
+    // We can't allow containers with dots in their names, as that would make
+    // their parameters not findable with parameters().
+    throw std::runtime_error("Trying to add parameter with a '.' in its name");
+  }
+  this->children_[name] = std::move(m);
+  return this->children_[name];
+}
+
+Variable& ContainerImpl::add(Variable v, std::string const& name) {
+  if (this->params_.find(name) != this->params_.end()) {
+    throw std::runtime_error("Trying to add parameter that already exists");
+  }
+  if (std::find(name.begin(), name.end(), '.') != name.end()) {
+    // We can't allow parameters with dots in their names, as that would make
+    // them not findable with parameters().
+    throw std::runtime_error("Trying to add parameter with a '.' in its name");
+  }
+  this->params_[name] = v;
+  return this->params_[name];
+}
+
+at::Type& ContainerImpl::DefaultTensor(at::ScalarType s) {
+  if (cuda_)
+    return at::CUDA(s);
+  else
+    return at::CPU(s);
+}
+
+variable_list Linear::forward(variable_list input) {
+  auto x = input[0];
+  if (x.ndimension() == 2 && !no_bias_) {
+    // Fused op is marginally faster
+    assert(x.size(1) == weight.size(1));
+    return variable_list({at::addmm(bias, x, weight.t())});
+  }
+
+  auto output = x.matmul(weight.t());
+  if (!no_bias_) {
+    output += bias;
+  }
+  return variable_list({output});
+}
+
+void Linear::reset_parameters() {
+  auto stdv = 1.0 / std::sqrt(weight.size(1));
+  for (auto& p : parameters()) {
+    p.second.data().uniform_(-stdv, stdv);
+  }
+}
+
+void Linear::initialize_parameters() {
+  weight = this->add(
+      Var(DefaultTensor(at::kFloat).tensor({nout, nin}), true), "weight");
+  if (!no_bias_) {
+    bias =
+        this->add(Var(DefaultTensor(at::kFloat).tensor({nout}), true), "bias");
+  }
+}
+
+variable_list Embedding::forward(variable_list input) {
+  auto x = input[0];
+  return variable_list({at::embedding(weight, x, -1, false, false)});
+}
+
+void Embedding::reset_parameters() {
+  for (auto& p : parameters()) {
+    p.second.data().normal_(0, 1);
+  }
+}
+
+void Embedding::initialize_parameters() {
+  weight = this->add(
+      Var(DefaultTensor(at::kFloat).tensor({num_embeddings, embedding_dim}),
+          true),
+      "weight");
+}
+
+void Conv::initialize_parameters() {
+  if (!transposed_) {
+    for (auto pad : output_padding_) {
+      if (pad != 0) {
+        throw std::runtime_error(
+            "Only transposed convolutions support output padding!");
+      }
+    }
+  }
+
+  IntVec wsize;
+  if (transposed_) {
+    wsize.push_back(in_channels_);
+    wsize.push_back(out_channels_ / groups_);
+  } else {
+    wsize.push_back(out_channels_);
+    wsize.push_back(in_channels_ / groups_);
+  }
+  wsize.insert(wsize.end(), ks_.begin(), ks_.end());
+  weight =
+      this->add(Var(DefaultTensor(at::kFloat).tensor(wsize), true), "weight");
+  if (!no_bias_) {
+    bias = this->add(
+        Var(DefaultTensor(at::kFloat).tensor({out_channels_}), true), "bias");
+  } else {
+    assert(!bias.defined());
+  }
+}
+
+void Conv::reset_parameters() {
+  auto n = in_channels_;
+  for (auto k : ks_)
+    n *= k;
+  auto stdv = 1.0 / std::sqrt(n);
+  for (auto& p : parameters()) {
+    p.second.data().uniform_(-stdv, stdv);
+  }
+}
+
+variable_list Conv::forward(variable_list input) {
+  auto x = input[0];
+  if (Nd_ == 1) {
+    assert(x.ndimension() == 3);
+    x = x.unsqueeze(-1); // TODO: Use conv1d once available
+  } else if (Nd_ == 2) {
+    assert(x.ndimension() == 4);
+  } else if (Nd_ == 3) {
+    assert(x.ndimension() == 5);
+  } else {
+    throw std::runtime_error("Only Conv{1,2,3}d are supported");
+  }
+
+  Variable out;
+  if (Nd_ == 1 || Nd_ == 2) {
+    if (transposed_) {
+      out = at::conv_transpose2d(
+          x,
+          weight,
+          bias,
+          stride_,
+          padding_,
+          output_padding_,
+          groups_,
+          dilation_);
+    } else {
+      out = at::conv2d(x, weight, bias, stride_, padding_, dilation_, groups_);
+    }
+  } else if (Nd_ == 3) {
+    if (transposed_) {
+      out = at::conv_transpose3d(
+          x,
+          weight,
+          bias,
+          stride_,
+          padding_,
+          output_padding_,
+          groups_,
+          dilation_);
+    } else {
+      out = at::conv3d(x, weight, bias, stride_, padding_, dilation_, groups_);
+    }
+  }
+
+  return variable_list({out});
+}
+
+void BatchNorm::initialize_parameters() {
+  if (affine_) {
+    weight = this->add(
+        Var(DefaultTensor(at::kFloat).tensor(num_features_), true), "weight");
+    bias = this->add(
+        Var(DefaultTensor(at::kFloat).tensor(num_features_), true), "bias");
+  }
+
+  if (stateful_) {
+    running_mean = Var(DefaultTensor(at::kFloat).zeros({num_features_}), false);
+    running_var = Var(DefaultTensor(at::kFloat).ones({num_features_}), false);
+  }
+}
+
+void BatchNorm::reset_parameters() {
+  if (affine_) {
+    weight.data().uniform_();
+    bias.data().zero_();
+  }
+
+  if (stateful_) {
+    running_mean.data().zero_();
+    running_var.data().fill_(1);
+  }
+}
+
+variable_list BatchNorm::forward(variable_list inputs) {
+  auto& input = inputs[0];
+  auto& running_mean = (stateful_ ? this->running_mean : inputs[1]);
+  auto& running_var = (stateful_ ? this->running_var : inputs[2]);
+
+  if (train_) {
+    const auto num_channels = input.dim() > 1 ? input.size(1) : 1;
+    if (input.numel() / num_channels <= 1) {
+      throw std::runtime_error(
+          "BatchNorm expected more than 1 value per channel when training!");
+    }
+  }
+
+  auto output = at::batch_norm(
+      input,
+      weight,
+      bias,
+      running_mean,
+      running_var,
+      train_,
+      momentum_,
+      eps_,
+      hasCudnn());
+
+  return variable_list({output});
+}
+
+template <typename Derived>
+void RNNBase<Derived>::initialize_containers() {
+  auto gate_size = hidden_size_;
+  if (mode_ == RNNMode::LSTM) {
+    gate_size *= 4;
+  } else if (mode_ == RNNMode::GRU) {
+    gate_size *= 3;
+  }
+
+  for (auto i = 0U; i < nlayers_; i++) {
+    auto input_size = (i == 0) ? input_size_ : hidden_size_;
+    i2h.push_back(this->add(
+        Linear(input_size, gate_size).no_bias(no_bias_).make(),
+        "i2h_" + std::to_string(i)));
+    h2h.push_back(this->add(
+        Linear(hidden_size_, gate_size).no_bias(no_bias_).make(),
+        "h2h_" + std::to_string(i)));
+  }
+  if (dropout_ > 0)
+    dropout_module = Dropout(dropout_).make();
+  this->flatten_parameters();
+}
+
+template <typename Derived>
+void RNNBase<Derived>::reset_parameters() {
+  auto stdv = 1.0 / std::sqrt(hidden_size_);
+  for (auto& p : this->parameters()) {
+    p.second.data().uniform_(-stdv, stdv);
+  }
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::GRU_cell_forward(variable_list inputs, int i) {
+  auto x = inputs[0];
+  auto hx = inputs[1].defined()
+      ? inputs[1]
+      : Var(this->DefaultTensor(at::kFloat).zeros({x.size(0), hidden_size_}));
+
+  auto gi = i2h[i]->forward({x})[0];
+  auto gh = h2h[i]->forward({hx})[0];
+  auto gic = gi.chunk(3, 1);
+  auto ghc = gh.chunk(3, 1);
+
+  auto reset_gate = (gic[0] + ghc[0]).sigmoid_();
+  auto input_gate = (gic[1] + ghc[1]).sigmoid_();
+  auto new_gate = (gic[2] + reset_gate * ghc[2]).tanh_();
+  auto hy = new_gate + input_gate * (hx - new_gate);
+
+  return variable_list({hy});
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::RNN_TANH_cell_forward(
+    variable_list inputs,
+    int i) {
+  auto x = inputs[0];
+  auto hx = inputs[1].defined()
+      ? inputs[1]
+      : Var(this->DefaultTensor(at::kFloat).zeros({x.size(0), hidden_size_}));
+
+  auto h = (i2h[i]->forward({x})[0] + h2h[i]->forward({hx})[0]).tanh();
+  return variable_list({h});
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::RNN_RELU_cell_forward(
+    variable_list inputs,
+    int i) {
+  auto x = inputs[0];
+  auto hx = inputs[1].defined()
+      ? inputs[1]
+      : Var(this->DefaultTensor(at::kFloat).zeros({x.size(0), hidden_size_}));
+
+  auto h = (i2h[i]->forward({x})[0] + h2h[i]->forward({hx})[0]).clamp_min(0);
+  return variable_list({h});
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::LSTM_cell_forward(variable_list inputs, int i) {
+  auto x = inputs[0];
+  auto hid = inputs[1].defined()
+      ? inputs[1]
+      : Var(this->DefaultTensor(at::kFloat)
+                .zeros({2, x.size(0), hidden_size_}));
+  auto hx = hid[0];
+  auto cx = hid[1];
+
+  auto gates = i2h[i]->forward({x})[0] + h2h[i]->forward({hx})[0];
+
+  auto chunked = gates.chunk(4, 1);
+  auto in_gate = chunked[0].sigmoid();
+  auto forget_gate = chunked[1].sigmoid();
+  auto cell_gate = chunked[2].tanh();
+  auto out_gate = chunked[3].sigmoid();
+
+  auto cy = (forget_gate * cx) + (in_gate * cell_gate);
+  auto hy = out_gate * cy.tanh();
+
+  return variable_list({at::stack({hy, cy}, 0)});
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::cell_forward(variable_list inputs, int i) {
+  if (mode_ == RNNMode::LSTM)
+    return LSTM_cell_forward(inputs, i);
+  else if (mode_ == RNNMode::GRU)
+    return GRU_cell_forward(inputs, i);
+  else if (mode_ == RNNMode::RNN_TANH)
+    return RNN_TANH_cell_forward(inputs, i);
+  else if (mode_ == RNNMode::RNN_RELU)
+    return RNN_RELU_cell_forward(inputs, i);
+  else
+    throw std::runtime_error("No such RNN mode");
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::autograd_forward(variable_list inputs) {
+  auto inp = inputs[0];
+
+  std::vector<Tensor> hidden;
+  for (size_t i = 0; i < nlayers_; i++) {
+    hidden.push_back(inputs[1].defined() ? inputs[1][i] : tag::Variable());
+  }
+
+  auto output =
+      Var(this->DefaultTensor(at::kFloat)
+              .zeros({inp.size(0), inp.size(1), hidden_size_}),
+          false);
+  for (auto t = 0U; t < inp.size(0); t++) {
+    auto x = inp.select(0, t);
+    for (size_t i = 0; i < nlayers_; i++) {
+      auto layer_output = cell_forward({x, hidden[i]}, i);
+      hidden[i] = layer_output[0];
+      if (mode_ == RNNMode::LSTM) {
+        x = hidden[i][0];
+      } else {
+        x = hidden[i];
+      }
+      auto output_slice = output.select(0, t);
+      output_slice.copy_(x);
+      if (dropout_ > 0 && i != nlayers_ - 1) {
+        x = dropout_module->forward({x})[0];
+      }
+    }
+  }
+
+  auto hidout = at::stack(hidden, 0);
+  return variable_list({output, hidout});
+}
+
+template <typename Derived>
+bool RNNBase<Derived>::flatten_parameters() {
+  data_ptrs_.clear();
+  auto anyParam = i2h[0]->params_.begin()->second;
+  if (!anyParam.is_cuda() || !at::cudnn_is_acceptable(anyParam)) {
+    return false;
+  }
+  std::unordered_set<void*> unique_data_ptrs;
+  auto params = this->parameters();
+  for (auto& p : params) {
+    unique_data_ptrs.insert(p.second.data().data_ptr());
+  }
+  // TODO PyTorch says:
+  // If any parameters alias, we fall back to the slower, copying code path.
+  // This is
+  // a sufficient check, because overlapping parameter buffers that don't
+  // completely
+  // alias would break the assumptions of the uniqueness check in
+  // Module.named_parameters().
+  // But I'm not sure if this is the case for us
+  if (unique_data_ptrs.size() != params.size()) {
+    return false;
+  }
+
+  std::vector<Tensor> weight_list;
+  for (size_t i = 0; i < nlayers_; i++) {
+    weight_list.push_back(i2h[i]->param("weight"));
+    weight_list.push_back(h2h[i]->param("weight"));
+    if (!no_bias_) {
+      weight_list.push_back(i2h[i]->param("bias"));
+      weight_list.push_back(h2h[i]->param("bias"));
+    }
+  }
+  auto weight_stride0 = no_bias_ ? 2 : 4;
+
+  {
+    no_grad_guard guard;
+    flat_weight_ = at::_cudnn_rnn_flatten_weight(
+        weight_list,
+        weight_stride0,
+        input_size_,
+        mode_,
+        hidden_size_,
+        nlayers_,
+        false,
+        false); // batch_first and bidirectional, unsupported
+  }
+  for (auto& p : params) {
+    data_ptrs_.emplace_back(p.second.data().data_ptr());
+  }
+  return true;
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::CUDNN_forward(variable_list inputs) {
+  std::vector<Tensor> weight_list;
+  for (size_t i = 0; i < nlayers_; i++) {
+    weight_list.push_back(i2h[i]->param("weight"));
+    weight_list.push_back(h2h[i]->param("weight"));
+    if (!no_bias_) {
+      weight_list.push_back(i2h[i]->param("bias"));
+      weight_list.push_back(h2h[i]->param("bias"));
+    }
+  }
+  auto weight_stride0 = no_bias_ ? 2 : 4;
+
+  auto x = inputs[0];
+  Variable hx, cx;
+  if (!inputs[1].defined()) {
+    hx = x.type().zeros({nlayers_, x.size(1), hidden_size_});
+    if (mode_ == RNNMode::LSTM) {
+      cx = x.type().zeros({nlayers_, x.size(1), hidden_size_});
+    }
+  } else {
+    hx = mode_ == RNNMode::LSTM ? inputs[1][0] : inputs[1];
+    cx = mode_ == RNNMode::LSTM ? inputs[1][1] : Variable();
+  }
+  auto dropout_state = x.type().tensor();
+
+  std::vector<void*> weight_data_ptrs;
+  auto params = this->parameters();
+  for (auto& p : params) {
+    weight_data_ptrs.emplace_back(p.second.data().data_ptr());
+  }
+  if (weight_data_ptrs != data_ptrs_) {
+    std::cerr << "Parameters are unflattened! Code path might be super slow. "
+                 "Please call flatten_parameters() when you muck around with "
+                 "storages!"
+              << std::endl;
+    flat_weight_ = Variable();
+  }
+
+  // tup = std::tuple of output, hy, cy, reserve, new_weight_buf
+  auto tup = _cudnn_rnn(
+      x,
+      weight_list,
+      weight_stride0,
+      flat_weight_,
+      hx,
+      cx,
+      mode_,
+      hidden_size_,
+      nlayers_,
+      false, // batch first
+      0, // TODO waiting on dropout state descriptor in C++ pytorch
+      this->train_,
+      false, // bidirectional
+      {}, // packing not supported
+      dropout_state // TODO waiting on dropout state descriptor in C++ pytorch
+  );
+
+  Variable hidout = mode_ == RNNMode::LSTM
+      ? at::stack({std::get<1>(tup), std::get<2>(tup)}, 0)
+      : std::get<1>(tup);
+  Variable output = std::get<0>(tup);
+  return variable_list({output, hidout});
+}
+
+template <typename Derived>
+variable_list RNNBase<Derived>::forward(variable_list inputs) {
+  variable_list inp;
+  inp.push_back(inputs[0]);
+  if (inputs.size() > 1) {
+    inp.push_back(inputs[1]);
+  } else {
+    inp.push_back(Variable());
+  }
+
+  // Dropout descriptors aren't in C++ in PyTorch yet...
+  auto output = at::cudnn_is_acceptable(inp[0]) && dropout_ == 0
+      ? CUDNN_forward(inp)
+      : autograd_forward(inp);
+
+  return output;
+}
+
+template <typename Derived>
+void RNNBase<Derived>::cuda() {
+  Container_CRTP<Derived>::cuda();
+  flatten_parameters();
+}
+
+template <typename Derived>
+void RNNBase<Derived>::cpu() {
+  Container_CRTP<Derived>::cpu();
+  flatten_parameters();
+}
+
+variable_list Dropout::forward(variable_list inputs) {
+  if (p_ == 0 || !this->train_)
+    return inputs;
+  variable_list lst;
+  for (auto x : inputs) {
+    auto noise = x.data().type().tensor(x.sizes());
+    noise = (noise.uniform_(0, 1) > p_)
+                .toType(x.type().scalarType())
+                .mul_(1. / (1 - p_));
+    lst.push_back(x * Var(noise));
+  }
+  return lst;
+}
+
+variable_list Dropout2d::forward(variable_list inputs) {
+  if (p_ == 0 || !this->train_)
+    return inputs;
+  variable_list lst;
+  for (auto x : inputs) {
+    auto noise = x.data().type().tensor({x.size(0), x.size(1), 1, 1});
+    noise = (noise.uniform_(0, 1) > p_)
+                .toType(x.type().scalarType())
+                .mul_(1. / (1 - p_));
+    lst.push_back(x * Var(noise));
+  }
+  return lst;
+}
+
+} // namespace autograd

torch/csrc/api/src/detail.cpp

@@ -0,0 +1,71 @@
+#include <ATen/Config.h>
+
+#include <algorithm>
+#include <cmath>
+#include <functional>
+#include <stdexcept>
+
+#if AT_CUDA_ENABLED()
+#include <THC/THCTensorRandom.h>
+#include <cuda.h>
+#include <cuda_runtime.h>
+#endif
+
+#include "torch/detail.h"
+
+namespace autograd {
+namespace detail {
+tag::Engine engine;
+}
+
+void backward(Variable loss, bool keep_graph) {
+  tag::edge_list edgelst;
+  tag::variable_list varlst;
+  edgelst.emplace_back(loss.grad_fn(), loss.output_nr());
+  varlst.emplace_back(Var(at::ones_like(loss.data()), false));
+  // create_graph should be set to true when we want to support double bwd
+  detail::engine.execute(edgelst, varlst, keep_graph, false);
+}
+
+void backward(Tensor loss, bool keep_graph) {
+  Variable tmp(loss);
+  backward(tmp, keep_graph);
+}
+
+void setSeed(uint64_t seed) {
+  at::globalContext().defaultGenerator(at::Backend::CPU).manualSeed(seed);
+#if AT_CUDA_ENABLED()
+  if (getNumGPUs() > 0) {
+    THCRandom_manualSeedAll(at::globalContext().lazyInitCUDA(), seed);
+  }
+#endif
+};
+
+int getNumGPUs() {
+#if AT_CUDA_ENABLED()
+  int count;
+  auto err = cudaGetDeviceCount(&count);
+  if (err == cudaErrorNoDevice) {
+    return 0;
+  } else if (err != cudaSuccess) {
+    std::string msg = "CUDA error (";
+    msg += std::to_string(err);
+    msg += "): ";
+    msg += cudaGetErrorString(err);
+    throw std::runtime_error(msg);
+  }
+  return count;
+#else
+  return 0;
+#endif
+}
+
+bool hasCuda() {
+  return getNumGPUs() > 0;
+}
+
+bool hasCudnn() {
+  return hasCuda() && AT_CUDNN_ENABLED();
+}
+
+} // namespace autograd

torch/csrc/api/src/optimizers.cpp

@@ -0,0 +1,199 @@
+#include "torch/optimizers.h"
+
+namespace autograd {
+
+void OptimizerImpl::zero_grad() {
+  for (auto p : model_->parameters()) {
+    auto& grad = p.second.grad();
+    if (grad.defined()) {
+      grad = grad.detach();
+      torch::autograd::as_variable_ref(grad).data().zero_();
+    }
+  }
+}
+
+void OptimizerImpl::set_model(Container model) {
+  model_ = model;
+}
+
+void SGD::step() {
+  for (auto& pair : model_->parameters()) {
+    auto& name = pair.first;
+    auto& grad = pair.second.grad();
+    auto& p = pair.second.data();
+    if (!grad.defined())
+      continue;
+
+    auto d_p = torch::autograd::as_variable_ref(grad).data();
+    if (weight_decay_ > 0) {
+      d_p.add_(p, weight_decay_);
+    };
+
+    if (momentum_ != 0) {
+      at::Tensor buf;
+      if (momentum_buffers_.find(name) == momentum_buffers_.end()) {
+        buf = momentum_buffers_[name] = at::zeros_like(p);
+        buf.mul_(momentum_).add_(d_p);
+      } else {
+        buf = momentum_buffers_[name];
+        buf.mul_(momentum_).add_(d_p, 1 - dampening_);
+      }
+
+      if (nesterov_) {
+        d_p = d_p.add(buf, momentum_);
+      } else {
+        d_p = buf;
+      }
+    }
+
+    p.add_(d_p, -lr_);
+  }
+}
+
+void SGD::init_state() {
+  momentum_buffers_.clear();
+}
+
+/// Adapted from
+/// https://github.com/pytorch/pytorch/blob/master/torch/optim/adagrad.py
+void Adagrad::step() {
+  for (auto& pair : model_->parameters()) {
+    auto& name = pair.first;
+    auto& grad = pair.second.grad();
+    auto& p = pair.second.data();
+    if (!grad.defined())
+      continue;
+
+    auto d_p = torch::autograd::as_variable_ref(grad).data();
+    if (weight_decay_ > 0) {
+      d_p.add_(p, weight_decay_);
+    };
+    auto& step = step_[name];
+    step += 1.0;
+    auto clr = lr_ / (1.0 + (step - 1.0) * lr_decay_);
+    at::Tensor buf;
+    if (sum_.find(name) == sum_.end()) {
+      buf = sum_[name] = at::zeros_like(p);
+    } else {
+      buf = sum_[name];
+    }
+
+    buf.addcmul_(d_p, d_p, 1.0);
+    at::Tensor std = buf.sqrt().add_(1e-10);
+    p.addcdiv_(d_p, std, -clr);
+  }
+}
+
+void Adagrad::init_state() {
+  sum_.clear();
+  step_.clear();
+}
+
+/// Adapted from
+/// https://github.com/pytorch/pytorch/blob/master/torch/optim/rmsprop.py
+void RMSprop::step() {
+  for (auto& pair : model_->parameters()) {
+    auto& name = pair.first;
+    auto& grad = pair.second.grad();
+    auto& p = pair.second.data();
+    if (!grad.defined())
+      continue;
+
+    if (square_avg_buffer_.find(name) == square_avg_buffer_.end()) {
+      square_avg_buffer_[name] = at::zeros_like(p);
+      if (momentum_) {
+        momentum_buffer_[name] = at::zeros_like(p);
+      };
+      if (centered_) {
+        grad_avg_buffer_[name] = at::zeros_like(p);
+      };
+    };
+
+    auto d_p = torch::autograd::as_variable_ref(grad).data();
+    if (weight_decay_ > 0) {
+      d_p.add_(p, weight_decay_);
+    };
+
+    auto& square_avg = square_avg_buffer_[name];
+    square_avg.mul_(alpha_).addcmul_(d_p, d_p, 1.0 - alpha_);
+
+    at::Tensor avg;
+    if (centered_) {
+      auto& grad_avg = grad_avg_buffer_[name];
+      grad_avg.mul_(alpha_).add_(d_p, 1.0 - alpha_);
+      avg = square_avg.addcmul(grad_avg, grad_avg, -1.0).sqrt().add_(eps_);
+    } else {
+      avg = square_avg.sqrt().add_(eps_);
+    };
+
+    if (momentum_ > 0) {
+      auto& buf = momentum_buffer_[name];
+      buf.mul_(momentum_).addcdiv_(d_p, avg);
+      p.add_(buf, -lr_);
+    } else {
+      p.addcdiv_(d_p, avg, -lr_);
+    };
+  }
+}
+
+void RMSprop::init_state() {
+  square_avg_buffer_.clear();
+  momentum_buffer_.clear();
+  grad_avg_buffer_.clear();
+}
+
+void Adam::step() {
+  for (auto& pair : model_->parameters()) {
+    auto& name = pair.first;
+    auto& grad = pair.second.grad();
+    auto& p = pair.second.data();
+    if (!grad.defined())
+      continue;
+
+    if (step_buffer_.find(name) == step_buffer_.end()) {
+      step_buffer_[name] = 0;
+      exp_avg_buffer_[name] = at::zeros_like(p);
+      exp_avg_sq_buffer_[name] = at::zeros_like(p);
+      if (amsgrad_) {
+        max_exp_avg_sq_buffer_[name] = at::zeros_like(p);
+      };
+    }
+
+    auto& step = step_buffer_[name];
+    auto& exp_avg = exp_avg_buffer_[name];
+    auto& exp_avg_sq = exp_avg_sq_buffer_[name];
+
+    step += 1;
+
+    auto d_p = torch::autograd::as_variable_ref(grad).data();
+    if (weight_decay_ > 0) {
+      d_p.add_(p, weight_decay_);
+    }
+
+    exp_avg.mul_(beta1_).add_(d_p, 1 - beta1_);
+    exp_avg_sq.mul_(beta2_).addcmul_(d_p, d_p, 1 - beta2_);
+
+    at::Tensor denom;
+    if (amsgrad_) {
+      auto& max_exp_avg_sq = max_exp_avg_sq_buffer_[name];
+      at::max_out(max_exp_avg_sq, max_exp_avg_sq, exp_avg_sq);
+      denom = max_exp_avg_sq.sqrt().add_(eps_);
+    } else {
+      denom = exp_avg_sq.sqrt().add_(eps_);
+    };
+
+    auto bias_correction1 = 1 - std::pow(beta1_, step);
+    auto bias_correction2 = 1 - std::pow(beta2_, step);
+    auto step_size = lr_ * std::sqrt(bias_correction2) / bias_correction1;
+
+    p.addcdiv_(exp_avg, denom, -step_size);
+  }
+}
+
+void Adam::init_state() {
+  step_buffer_.clear();
+  exp_avg_buffer_.clear();
+  exp_avg_sq_buffer_.clear();
+}
+
+} // namespace autograd