chore: import upstream snapshot with attribution

test/cpp/compat/ATen_coalesce_test.cc

@@ -0,0 +1,115 @@
+// Copyright (c) 2026 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <ATen/Functions.h>
+#include <ATen/core/TensorBody.h>
+#include <ATen/cuda/EmptyTensor.h>
+#include <ATen/native/cuda/Resize.h>
+#include <ATen/ops/tensor.h>
+#include <c10/core/ScalarType.h>
+#include <c10/core/SymInt.h>
+#include <c10/core/TensorOptions.h>
+#if defined(PADDLE_WITH_CUDA) || defined(PADDLE_WITH_HIP)
+#include <c10/cuda/CUDAFunctions.h>
+#include <c10/cuda/CUDAGuard.h>
+#endif
+#include "ATen/ATen.h"
+#include "gtest/gtest.h"
+#include "paddle/phi/common/float16.h"
+#include "torch/all.h"
+
+// ============================================================
+// Tests for at::Tensor::coalesce() and at::Tensor::is_coalesced()
+// ============================================================
+
+// Helper: build a 2-D sparse COO tensor from indices and values.
+// indices shape: [sparse_dim, nnz], values shape: [nnz]
+static at::Tensor make_sparse(at::Tensor indices,
+                              at::Tensor values,
+                              c10::IntArrayRef size) {
+  return at::sparse_coo_tensor(indices, values, size);
+}
+
+TEST(TensorCoalesceTest, NewSparseNotCoalesced) {
+  // A freshly created sparse COO tensor reports is_coalesced() == false.
+  at::Tensor indices =
+      at::tensor({0, 0, 1, 1, 1, 2}, at::kLong).reshape({2, 3});
+  at::Tensor values = at::tensor({1.0f, 2.0f, 3.0f}, at::kFloat);
+  at::Tensor sparse = make_sparse(indices, values, {3, 3});
+
+  ASSERT_FALSE(sparse.is_coalesced());
+}
+
+TEST(TensorCoalesceTest, CoalesceReturnsSparse) {
+  // coalesce() returns a sparse COO tensor.
+  at::Tensor indices =
+      at::tensor({0, 0, 1, 1, 1, 2}, at::kLong).reshape({2, 3});
+  at::Tensor values = at::tensor({1.0f, 2.0f, 3.0f}, at::kFloat);
+  at::Tensor sparse = make_sparse(indices, values, {3, 3});
+
+  at::Tensor coalesced = sparse.coalesce();
+
+  ASSERT_EQ(coalesced.layout(), c10::kSparse);
+}
+
+TEST(TensorCoalesceTest, CoalescedTensorIsCoalesced) {
+  // After calling coalesce(), is_coalesced() must return true.
+  at::Tensor indices =
+      at::tensor({0, 0, 1, 1, 1, 2}, at::kLong).reshape({2, 3});
+  at::Tensor values = at::tensor({1.0f, 2.0f, 3.0f}, at::kFloat);
+  at::Tensor sparse = make_sparse(indices, values, {3, 3});
+
+  at::Tensor coalesced = sparse.coalesce();
+
+  ASSERT_TRUE(coalesced.is_coalesced());
+}
+
+TEST(TensorCoalesceTest, CoalesceDuplicateIndices_SumsValues) {
+  // Duplicate indices [(0,1) appears twice] are merged; values are summed.
+  // indices = [[0,0],[1,1]]  (both at (0,1))
+  at::Tensor indices = at::tensor({0, 0, 1, 1}, at::kLong).reshape({2, 2});
+  at::Tensor values = at::tensor({1.0f, 2.0f}, at::kFloat);
+  at::Tensor sparse = make_sparse(indices, values, {3, 3});
+
+  at::Tensor coalesced = sparse.coalesce();
+  ASSERT_TRUE(coalesced.is_coalesced());
+  // After coalescing, nnz should be 1 (duplicates merged)
+  ASSERT_EQ(coalesced._nnz(), 1);
+  // The merged value at (0,1) should be 1+2 = 3
+  ASSERT_FLOAT_EQ(coalesced._values()[0].item<float>(), 3.0f);
+}
+
+TEST(TensorCoalesceTest, CoalesceIdempotent) {
+  // Calling coalesce() on an already-coalesced tensor returns the same tensor.
+  at::Tensor indices = at::tensor({0, 1, 1, 2}, at::kLong).reshape({2, 2});
+  at::Tensor values = at::tensor({1.0f, 2.0f}, at::kFloat);
+  at::Tensor sparse = make_sparse(indices, values, {3, 3});
+
+  at::Tensor coalesced1 = sparse.coalesce();
+  at::Tensor coalesced2 = coalesced1.coalesce();  // already coalesced
+
+  ASSERT_TRUE(coalesced2.is_coalesced());
+}
+
+TEST(TensorCoalesceTest, CoalesceOnDenseTensorThrows) {
+  // coalesce() on a dense tensor must throw.
+  at::Tensor dense = at::ones({3, 3}, at::kFloat);
+  ASSERT_THROW(dense.coalesce(), std::exception);
+}
+
+TEST(TensorCoalesceTest, IsCoalescedOnDenseTensorThrows) {
+  // is_coalesced() on a dense tensor must throw.
+  at::Tensor dense = at::ones({3, 3}, at::kFloat);
+  ASSERT_THROW(dense.is_coalesced(), std::exception);
+}