[Phi] Add unbind yaml and final state api (#41277)

* add unbind yaml

* fix unittest

paddle/phi/api/lib/api_custom_impl.cc

@@ -475,6 +475,54 @@ std::tuple<Tensor, Tensor, Tensor> momentum_impl(
   return api_output;
 }
 
+std::vector<Tensor> unbind_impl(const Tensor& input, int axis) {
+  auto kernel_key_set = ParseKernelKeyByInputArgs(input);
+  auto kernel_key = kernel_key_set.GetHighestPriorityKernelKey();
+
+  Backend kernel_backend = kernel_key.backend();
+  DataLayout kernel_layout = kernel_key.layout();
+  DataType kernel_data_type = kernel_key.dtype();
+
+  auto kernel = phi::KernelFactory::Instance().SelectKernelOrThrowError(
+      "unbind", {kernel_backend, kernel_layout, kernel_data_type});
+  VLOG(6) << "unbind API kernel key: [" << kernel_backend << ", "
+          << kernel_layout << ", " << kernel_data_type << "]";
+  VLOG(6) << "unbind API kernel: " << kernel;
+
+  auto* dev_ctx = GetDeviceContextByBackend(kernel_backend);
+
+  auto dense_input = PrepareData(input, kernel.InputAt(0), {});
+
+  // Calculate the number of out tensors
+  auto input_shape = input.dims();
+  if (axis < 0) {
+    axis = input_shape.size() + axis;
+  }
+  auto out_num = input_shape[axis];
+
+  std::vector<Tensor> out;
+  auto dense_outs = SetKernelOutput(out_num, kernel_backend, &out);
+  std::vector<phi::MetaTensor> meta_outs;
+  meta_outs.reserve(out_num);
+  std::vector<phi::MetaTensor*> meta_out_ptrs;
+  meta_out_ptrs.reserve(out_num);
+  for (int64_t i = 0; i < out_num; ++i) {
+    meta_outs.push_back(dense_outs[i]);
+    meta_out_ptrs.push_back(&meta_outs.back());
+  }
+
+  phi::UnbindInferMeta(MakeMetaTensor(*dense_input), axis, meta_out_ptrs);
+
+  using kernel_signature = void (*)(const phi::DeviceContext&,
+                                    const phi::DenseTensor&,
+                                    int,
+                                    std::vector<phi::DenseTensor*>&);
+  auto* kernel_fn = kernel.GetVariadicKernelFn<kernel_signature>();
+  (*kernel_fn)(*dev_ctx, *dense_input, axis, dense_outs);
+
+  return out;
+}
+
 ////////////////// Backward(grad) api impls //////////////////////
 
 // TODO(chenweihang):  the original sum grad op can support higher-level

paddle/phi/api/lib/api_custom_impl.h

@@ -14,6 +14,8 @@ limitations under the License. */
 
 #pragma once
 
+#include <vector>
+
 #include "paddle/phi/api/include/tensor.h"
 #include "paddle/phi/common/int_array.h"
 #include "paddle/phi/common/place.h"
@@ -73,6 +75,8 @@ std::tuple<Tensor, Tensor, Tensor> momentum_impl(
     bool multi_precision,
     float rescale_grad);
 
+std::vector<Tensor> unbind_impl(const Tensor& input, int axis);
+
 ////////////////// Backward(grad) api impls //////////////////////
 
 std::vector<Tensor> add_n_grad_impl(const std::vector<Tensor>& x,

paddle/phi/infermeta/unary.cc

@@ -2429,7 +2429,7 @@ void TransposeGradInferMeta(const MetaTensor& x,
 
 void UnbindInferMeta(const MetaTensor& x,
                      int axis,
-                     std::vector<MetaTensor>* outs) {
+                     std::vector<MetaTensor*> outs) {
   auto in_dims = x.dims();
   std::vector<int> out_dim;
   axis = axis < 0 ? in_dims.size() + axis : axis;
@@ -2438,11 +2438,11 @@ void UnbindInferMeta(const MetaTensor& x,
   }
   auto out_dims = phi::make_ddim(out_dim);
 
-  for (size_t i = 0; i < outs->size(); ++i) {
-    (*outs)[i].set_dtype(x.dtype());
-    (*outs)[i].set_dims(out_dims);
-    (*outs)[i].set_layout(x.layout());
-    (*outs)[i].share_lod(x);
+  for (size_t i = 0; i < outs.size(); ++i) {
+    outs[i]->set_dtype(x.dtype());
+    outs[i]->set_dims(out_dims);
+    outs[i]->set_layout(x.layout());
+    outs[i]->share_lod(x);
   }
 }
 

paddle/phi/infermeta/unary.h

@@ -365,7 +365,7 @@ void TrilTriuInferMeta(const MetaTensor& x,
 
 void UnbindInferMeta(const MetaTensor& x,
                      int axis,
-                     std::vector<MetaTensor>* outs);
+                     std::vector<MetaTensor*> outs);
 
 void UnchangedInferMeta(const MetaTensor& x, MetaTensor* out);
 

python/paddle/fluid/tests/unittests/test_unbind_op.py

@@ -17,9 +17,11 @@ from __future__ import print_function
 import unittest
 import numpy as np
 from op_test import OpTest, convert_float_to_uint16
+import paddle
 import paddle.fluid as fluid
 import paddle.tensor as tensor
 from paddle.fluid import compiler, Program, program_guard, core
+from paddle.fluid.framework import _test_eager_guard
 
 
 class TestUnbind(unittest.TestCase):
@@ -39,6 +41,25 @@ class TestUnbind(unittest.TestCase):
         assert np.array_equal(res_1, input_1[0, 0:100])
         assert np.array_equal(res_2, input_1[1, 0:100])
 
+    def test_unbind_dygraph(self):
+        with fluid.dygraph.guard():
+            np_x = np.random.random([2, 3]).astype("float32")
+            x = paddle.to_tensor(np_x)
+            x.stop_gradient = False
+            [res_1, res_2] = paddle.unbind(x, 0)
+            self.assertTrue(np.array_equal(res_1, np_x[0, 0:100]))
+            self.assertTrue(np.array_equal(res_2, np_x[1, 0:100]))
+
+            out = paddle.add_n([res_1, res_2])
+
+            np_grad = np.ones(x.shape, np.float32)
+            out.backward()
+            self.assertTrue(np.array_equal(x.grad.numpy(), np_grad))
+
+    def test_unbind_dygraph_final_state(self):
+        with _test_eager_guard():
+            self.test_unbind_dygraph()
+
 
 class TestLayersUnbind(unittest.TestCase):
     def test_layers_unbind(self):
@@ -157,6 +178,7 @@ class TestUnbindOp4(TestUnbindOp):
 class TestUnbindBF16Op(OpTest):
     def setUp(self):
         self._set_op_type()
+        self.python_api = paddle.unbind
         self.dtype = self.get_dtype()
         self.axis = 0
         self.num = 3

python/paddle/tensor/manipulation.py

@@ -1469,6 +1469,9 @@ def unbind(input, axis=0):
             # x3.shape [3, 5]
 
     """
+    if in_dygraph_mode():
+        return _C_ops.final_state_unbind(input, axis)
+
     if not isinstance(axis, (int)):
         raise TypeError("The type of 'axis'  must be int, but received %s." %
                         (type(axis)))
@@ -1477,7 +1480,7 @@ def unbind(input, axis=0):
     input_shape = input.shape
     axis_ = axis if axis >= 0 else len(input_shape) + axis
     num = input_shape[axis_]
-    if paddle.in_dynamic_mode():
+    if _in_legacy_dygraph():
         return _C_ops.unbind(input, num, 'axis', axis)
 
     helper = LayerHelper("unbind", **locals())

python/paddle/utils/code_gen/api.yaml

@@ -1939,6 +1939,12 @@
     backend : place
     data_type : dtype
 
+- api : unbind
+  args : (Tensor input, int axis)
+  output : Tensor[]
+  invoke : unbind_impl(input, axis)
+  backward : unbind_grad
+
 # unfold
 - api : unfold
   args : (Tensor x, int[] kernel_sizes, int[] strides, int[] paddings, int[] dilations)

python/paddle/utils/code_gen/backward.yaml

@@ -1480,6 +1480,12 @@
   kernel :
     func : trunc_grad
 
+- backward_api : unbind_grad
+  forward : unbind (Tensor input, int axis) -> Tensor[](out)
+  args : (Tensor[] out_grad, int axis)
+  output : Tensor(input_grad)
+  invoke : stack(out_grad, axis)
+
 - backward_api : unfold_grad
   forward : unfold (Tensor x, int[] kernel_sizes, int[] strides, int[] paddings, int[] dilations) -> Tensor(out)
   args : (Tensor x, Tensor out_grad, int[] kernel_sizes, int[] strides, int[] paddings, int[] dilations)