[Zero-Dim] Support 0D for paddle.diagflat (#48735)

* [Zero-Dim] Support 0D for paddle.diagflat

paddle/phi/infermeta/unary.cc

@@ -563,8 +563,8 @@ void DiagInferMeta(const MetaTensor& x,
                    MetaTensor* out) {
   auto x_dims = x.dims();
 
-  if (x_dims.size() == 1UL) {
-    int64_t size_ = x_dims[0] + std::abs(offset);
+  if (x_dims.size() <= 1) {
+    int64_t size_ = (x_dims.size() == 1UL ? x_dims[0] : 1) + std::abs(offset);
     out->set_dims({size_, size_});
     out->set_dtype(x.dtype());
   } else if (x_dims.size() == 2UL) {

paddle/phi/kernels/cpu/diag_grad_kernel.cc

@@ -32,9 +32,9 @@ void DiagGradKernel(const Context& dev_ctx,
   auto dx_dims = x_grad->dims();
   auto dout_dims = out_grad.dims();
 
-  if (dx_dims.size() == 1) {
-    auto dx_length = dx_dims[0];
-    int dx_stride = phi::funcs::ComputeStride(0, dx_dims);
+  if (dx_dims.size() <= 1) {
+    auto dx_length = (dx_dims.size() == 1 ? dx_dims[0] : int64_t(1));
+    int dx_stride = 1;
 
     auto dout_stride_0 = phi::funcs::ComputeStride(0, dout_dims);
     auto dout_stride_1 = phi::funcs::ComputeStride(1, dout_dims);

paddle/phi/kernels/cpu/diag_kernel.cc

@@ -33,12 +33,12 @@ void DiagKernel(const Context& dev_ctx,
   auto out_dims = out->dims();
 
   int64_t i;
-  if (x_dims.size() == 1) {
+  if (x_dims.size() <= 1) {
     phi::funcs::SetConstant<Context, T> set_padding_value;
     set_padding_value(dev_ctx, out, static_cast<T>(padding_value));
 
-    auto x_length = x_dims[0];
-    const int& x_stride = phi::funcs::ComputeStride(0, x_dims);
+    auto x_length = (x_dims.size() == 1UL ? x_dims[0] : int64_t(1));
+    const int& x_stride = 1;
 
     auto out_stride_0 = phi::funcs::ComputeStride(0, out_dims);
     auto out_stride_1 = phi::funcs::ComputeStride(1, out_dims);

paddle/phi/kernels/gpu/diag_grad_kernel.cu

@@ -73,10 +73,10 @@ void DiagGradKernel(const Context& dev_ctx,
     return std::tuple<int64_t, int64_t>{block_size, grid_size};
   };
 
-  if (dx_dims.size() == 1) {
-    auto dx_length = dx_dims[0];
+  if (dx_dims.size() <= 1) {
+    auto dx_length = (dx_dims.size() == 1 ? dx_dims[0] : int64_t(1));
     auto size = (offset > 0) ? dx_length + offset : dx_length - offset;
-    int dx_stride = phi::funcs::ComputeStride(0, dx_dims);
+    int dx_stride = 1;
     if (size > 0) {
       auto dout_stride_0 = phi::funcs::ComputeStride(0, dout_dims);
       auto dout_stride_1 = phi::funcs::ComputeStride(1, dout_dims);

paddle/phi/kernels/gpu/diag_kernel.cu

@@ -77,13 +77,13 @@ void DiagKernel(const Context& dev_ctx,
     return std::tuple<int64_t, int64_t>{block_size, grid_size};
   };
 
-  if (x_dims.size() == 1) {
+  if (x_dims.size() <= 1) {
     phi::funcs::SetConstant<Context, T> set_padding_value;
     set_padding_value(dev_ctx, out, static_cast<T>(padding_value));
 
-    auto x_length = x_dims[0];
+    auto x_length = (x_dims.size() == 1UL ? x_dims[0] : int64_t(1));
     auto size = (offset > 0) ? x_length + offset : x_length - offset;
-    const int& x_stride = phi::funcs::ComputeStride(0, x_dims);
+    const int& x_stride = 1;
     if (size > 0) {
       const auto& out_stride_0 = phi::funcs::ComputeStride(0, out_dims);
       const auto& out_stride_1 = phi::funcs::ComputeStride(1, out_dims);

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

@@ -653,6 +653,35 @@ class TestSundryAPI(unittest.TestCase):
             self.assertEqual(out.numpy()[1][i], updates.numpy()[i])
         self.assertEqual(out.grad.shape, [2, 3])
 
+    def test_diagflat(self):
+        x1 = paddle.rand([])
+        x2 = paddle.rand([])
+        x3 = paddle.rand([])
+
+        x1.stop_gradient = False
+        x2.stop_gradient = False
+        x3.stop_gradient = False
+
+        out1 = paddle.diagflat(x1, 1)
+        out2 = paddle.diagflat(x2, -1)
+        out3 = paddle.diagflat(x3, 0)
+
+        out1.backward()
+        out2.backward()
+        out3.backward()
+
+        self.assertEqual(out1.shape, [2, 2])
+        self.assertEqual(out2.shape, [2, 2])
+        self.assertEqual(out3.shape, [1, 1])
+
+        self.assertEqual(out1.grad.shape, [2, 2])
+        self.assertEqual(out2.grad.shape, [2, 2])
+        self.assertEqual(out3.grad.shape, [1, 1])
+
+        self.assertEqual(x1.grad.shape, [])
+        self.assertEqual(x2.grad.shape, [])
+        self.assertEqual(x3.grad.shape, [])
+
 
 class TestSundryAPIStatic(unittest.TestCase):
     def setUp(self):
@@ -796,6 +825,26 @@ class TestSundryAPIStatic(unittest.TestCase):
         for i in range(3):
             self.assertEqual(res[0][1][i], 4)
 
+    @prog_scope()
+    def test_diagflat(self):
+        x1 = paddle.rand([])
+        out1 = paddle.diagflat(x1, 1)
+        paddle.static.append_backward(out1)
+
+        x2 = paddle.rand([])
+        out2 = paddle.diagflat(x2, -1)
+        paddle.static.append_backward(out2)
+
+        x3 = paddle.rand([])
+        out3 = paddle.diagflat(x3)
+        paddle.static.append_backward(out3)
+
+        prog = paddle.static.default_main_program()
+        res1, res2, res3 = self.exe.run(prog, fetch_list=[out1, out2, out3])
+        self.assertEqual(res1.shape, (2, 2))
+        self.assertEqual(res2.shape, (2, 2))
+        self.assertEqual(res3.shape, (1, 1))
+
 
 # Use to test API whose zero-dim input tensors don't have grad and not need to test backward in OpTest.
 class TestNoBackwardAPI(unittest.TestCase):

python/paddle/fluid/tests/unittests/xpu/test_zero_dim_tensor_xpu.py

@@ -475,6 +475,35 @@ class TestSundryAPI(unittest.TestCase):
         for i in range(3):
             self.assertEqual(out.numpy()[1][i], updates.numpy()[i])
 
+    def test_diagflat(self):
+        x1 = paddle.rand([])
+        x2 = paddle.rand([])
+        x3 = paddle.rand([])
+
+        x1.stop_gradient = False
+        x2.stop_gradient = False
+        x3.stop_gradient = False
+
+        out1 = paddle.diagflat(x1, 1)
+        out2 = paddle.diagflat(x2, -1)
+        out3 = paddle.diagflat(x3, 0)
+
+        out1.backward()
+        out2.backward()
+        out3.backward()
+
+        self.assertEqual(out1.shape, [2, 2])
+        self.assertEqual(out2.shape, [2, 2])
+        self.assertEqual(out3.shape, [1, 1])
+
+        self.assertEqual(out1.grad.shape, [2, 2])
+        self.assertEqual(out2.grad.shape, [2, 2])
+        self.assertEqual(out3.grad.shape, [1, 1])
+
+        self.assertEqual(x1.grad.shape, [])
+        self.assertEqual(x2.grad.shape, [])
+        self.assertEqual(x3.grad.shape, [])
+
 
 # Use to test API whose zero-dim input tensors don't have grad and not need to test backward in OpTest.
 class TestNoBackwardAPI(unittest.TestCase):

python/paddle/tensor/creation.py

@@ -1479,7 +1479,7 @@ def diagflat(x, offset=0, name=None):
     """
     padding_value = 0
     if in_dygraph_mode():
-        if len(x.shape) == 1:
+        if len(x.shape) <= 1:
             return _C_ops.diag(x, offset, padding_value)
         else:
             y = _C_ops.flatten(x, 0, -1)
@@ -1509,7 +1509,7 @@ def diagflat(x, offset=0, name=None):
     out1_shape = helper.create_variable_for_type_inference(x.dtype)
     out2 = helper.create_variable_for_type_inference(dtype=x.dtype)
 
-    if len(x.shape) == 1:
+    if len(x.shape) <= 1:
         helper.append_op(
             type='diag_v2',
             inputs={'X': x},