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diff --git a/ruy/denormal.h b/ruy/denormal.h
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+++ b/ruy/denormal.h
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+/* Copyright 2021 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 RUY_RUY_DENORMAL_H_
+#define RUY_RUY_DENORMAL_H_
+
+#include <cstdint>
+
+namespace ruy {
+// NOTE: the following 'fpu_state' struct is copied from
+// pthreadpool/src/threadpool-utils.h that's not exposed by the pthreadpool
+// library (https://github.com/Maratyszcza/pthreadpool).
+struct fpu_state {
+#if defined(__SSE__) || defined(__x86_64__) || defined(_M_X64) || \
+    (defined(_M_IX86_FP) && _M_IX86_FP >= 1)
+  std::uint32_t mxcsr;
+#elif defined(__GNUC__) && defined(__arm__) && defined(__ARM_FP) && \
+        (__ARM_FP != 0) ||                                          \
+    defined(_MSC_VER) && defined(_M_ARM)
+  std::uint32_t fpscr;
+#elif defined(__GNUC__) && defined(__aarch64__) || \
+    defined(_MSC_VER) && defined(_M_ARM64)
+  std::uint64_t fpcr;
+#endif
+};
+
+// While this class is active, denormal floating point numbers are suppressed.
+// The destructor restores the original flags.
+class ScopedSuppressDenormals {
+ public:
+  ScopedSuppressDenormals();
+  ~ScopedSuppressDenormals();
+
+ private:
+  fpu_state restore_;
+
+  ScopedSuppressDenormals(const ScopedSuppressDenormals&) = delete;
+  void operator=(const ScopedSuppressDenormals&) = delete;
+};
+}  // namespace ruy
+
+#endif  // RUY_RUY_DENORMAL_H_