chore: import upstream snapshot with attribution

paddle/phi/kernels/funcs/multinomial_kernel_helper.h

@@ -0,0 +1,62 @@
+// Copyright (c) 2024 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.
+
+#pragma once
+
+#include "paddle/phi/common/amp_type_traits.h"
+#include "paddle/phi/common/scalar.h"
+#include "paddle/phi/core/dense_tensor.h"
+#include "paddle/phi/core/tensor_utils.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void MultinomialInputChecker(const Context& dev_ctx,
+                             const DenseTensor& x,
+                             const Scalar& num_samples) {
+  using MT = typename MPTypeTrait<T>::Type;
+  auto in_dims = x.dims();
+  int64_t dim_size = in_dims.size();
+  const int64_t num_categories = in_dims[dim_size - 1];
+  const int64_t num_distributions = dim_size > 1 ? in_dims[dim_size - 2] : 1;
+  auto int_num_samples = num_samples.to<int>();
+
+  DenseTensor cpu_tensor;
+  phi::Copy<Context>(dev_ctx, x, CPUPlace(), false, &cpu_tensor);
+  T* cpu_in_data = cpu_tensor.data<T>();
+  for (int64_t i = 0; i < num_distributions; ++i) {
+    int zero_num = 0;
+    for (int64_t j = 0; j < num_categories; ++j) {
+      T weight = cpu_in_data[i * num_categories + j];
+      PADDLE_ENFORCE_GE(
+          static_cast<MT>(weight),
+          0,
+          errors::InvalidArgument(
+              "Each element of multinomial'input must >= 0, but got %f.",
+              static_cast<MT>(weight)));
+      if (weight == static_cast<T>(0)) {
+        zero_num++;
+      }
+    }
+    int valid_samples = num_categories - zero_num;
+    PADDLE_ENFORCE_LE(
+        int_num_samples,
+        valid_samples,
+        errors::InvalidArgument("When replacement=False, 'num_samples' "
+                                "must less than or equal to the number of "
+                                "positive item of input"));
+  }
+}
+
+}  // namespace phi