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- /*
- * Copyright 2011-present Facebook, Inc.
- *
- * 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
- #if __GNUC__
- #define FOLLY_DETAIL_BUILTIN_EXPECT(b, t) (__builtin_expect(b, t))
- #else
- #define FOLLY_DETAIL_BUILTIN_EXPECT(b, t) b
- #endif
- // Likeliness annotations
- //
- // Useful when the author has better knowledge than the compiler of whether
- // the branch condition is overwhelmingly likely to take a specific value.
- //
- // Useful when the author has better knowledge than the compiler of which code
- // paths are designed as the fast path and which are designed as the slow path,
- // and to force the compiler to optimize for the fast path, even when it is not
- // overwhelmingly likely.
- #define FOLLY_LIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 1)
- #define FOLLY_UNLIKELY(x) FOLLY_DETAIL_BUILTIN_EXPECT((x), 0)
- // Un-namespaced annotations
- #undef LIKELY
- #undef UNLIKELY
- #if defined(__GNUC__)
- #define LIKELY(x) (__builtin_expect((x), 1))
- #define UNLIKELY(x) (__builtin_expect((x), 0))
- #else
- #define LIKELY(x) (x)
- #define UNLIKELY(x) (x)
- #endif
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