rocksdb/thrift/folly/Likely.h

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/*
* Copyright 2012 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.
*/
/**
* Compiler hints to indicate the fast path of an "if" branch: whether
* the if condition is likely to be true or false.
*
* @author Tudor Bosman (tudorb@fb.com)
*/
#ifndef FOLLY_BASE_LIKELY_H_
#define FOLLY_BASE_LIKELY_H_
#undef LIKELY
#undef UNLIKELY
#if defined(__GNUC__) && __GNUC__ >= 4
#define LIKELY(x) (__builtin_expect((x), 1))
#define UNLIKELY(x) (__builtin_expect((x), 0))
#else
#define LIKELY(x) (x)
#define UNLIKELY(x) (x)
#endif
#endif /* FOLLY_BASE_LIKELY_H_ */