chore: import upstream snapshot with attribution

paddle/phi/api/include/compat/c10/util/bits.h

@@ -0,0 +1,76 @@
+// 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.
+
+// The file has been adapted from pytorch project
+// Licensed under BSD-style license -
+// https://github.com/pytorch/pytorch/blob/main/LICENSE
+
+#pragma once
+
+#include <cstdint>
+
+namespace c10 {
+
+struct bits1x8 {
+  constexpr bits1x8() = default;
+  explicit constexpr bits1x8(uint8_t value) : val_(value) {}
+
+  uint8_t val_{0};
+};
+
+struct bits2x4 {
+  constexpr bits2x4() = default;
+  explicit constexpr bits2x4(uint8_t value) : val_(value) {}
+
+  uint8_t val_{0};
+};
+
+struct bits4x2 {
+  constexpr bits4x2() = default;
+  explicit constexpr bits4x2(uint8_t value) : val_(value) {}
+
+  uint8_t val_{0};
+};
+
+struct bits8 {
+  constexpr bits8() = default;
+  explicit constexpr bits8(uint8_t value) : val_(value) {}
+
+  uint8_t val_{0};
+};
+
+struct bits16 {
+  constexpr bits16() = default;
+  explicit constexpr bits16(uint16_t value) : val_(value) {}
+
+  uint16_t val_{0};
+};
+
+}  // namespace c10
+
+namespace at {
+using c10::bits16;
+using c10::bits1x8;
+using c10::bits2x4;
+using c10::bits4x2;
+using c10::bits8;
+}  // namespace at
+
+namespace torch {
+using c10::bits16;
+using c10::bits1x8;
+using c10::bits2x4;
+using c10::bits4x2;
+using c10::bits8;
+}  // namespace torch