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diff --git a/ruy/size_util.h b/ruy/size_util.h
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+/* Copyright 2019 Google LLC. 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.
+==============================================================================*/
+
+#ifndef TENSORFLOW_LITE_EXPERIMENTAL_RUY_RUY_SIZE_UTIL_H_
+#define TENSORFLOW_LITE_EXPERIMENTAL_RUY_RUY_SIZE_UTIL_H_
+
+#include <type_traits>
+
+#include "ruy/check_macros.h"
+
+#ifdef _WIN32
+#include <intrin.h>
+#endif
+
+namespace ruy {
+
+template <typename Integer>
+inline Integer floor_log2(Integer n) {
+  static_assert(std::is_integral<Integer>::value, "");
+  static_assert(std::is_signed<Integer>::value, "");
+  static_assert(sizeof(Integer) == 4 || sizeof(Integer) == 8, "");
+
+  RUY_DCHECK_GE(n, 1);
+#ifdef _WIN32
+  unsigned long result;  // NOLINT[runtime/int]
+  if (sizeof(Integer) == 4) {
+    _BitScanReverse(&result, n);
+  } else {
+    _BitScanReverse64(&result, n);
+  }
+  return result;
+#else
+  if (sizeof(Integer) == 4) {
+    return 31 - __builtin_clz(n);
+  } else {
+    return 63 - __builtin_clzll(n);
+  }
+#endif
+}
+
+template <typename Integer>
+Integer ceil_log2(Integer n) {
+  RUY_DCHECK_GE(n, 1);
+  return n == 1 ? 0 : floor_log2(n - 1) + 1;
+}
+
+template <typename Integer>
+bool is_pot(Integer value) {
+  return (value > 0) && ((value & (value - 1)) == 0);
+}
+
+template <typename Integer>
+Integer pot_log2(Integer n) {
+  RUY_DCHECK(is_pot(n));
+  return floor_log2(n);
+}
+
+template <typename Integer>
+Integer round_down_pot(Integer value) {
+  return static_cast<Integer>(1) << floor_log2(value);
+}
+
+template <typename Integer>
+Integer round_up_pot(Integer value) {
+  return static_cast<Integer>(1) << ceil_log2(value);
+}
+
+template <typename Integer, typename Modulo>
+Integer round_down_pot(Integer value, Modulo modulo) {
+  RUY_DCHECK_EQ(modulo & (modulo - 1), 0);
+  return value & ~(modulo - 1);
+}
+
+template <typename Integer, typename Modulo>
+Integer round_up_pot(Integer value, Modulo modulo) {
+  return round_down_pot(value + modulo - 1, modulo);
+}
+
+}  // namespace ruy
+
+#endif  // TENSORFLOW_LITE_EXPERIMENTAL_RUY_RUY_SIZE_UTIL_H_