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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.
*/
#ifndef FOLLY_DETAIL_BITSDETAIL_H_
#define FOLLY_DETAIL_BITSDETAIL_H_
namespace folly {
namespace detail {
// If we're targeting an architecture with popcnt support, use
// __builtin_popcount directly, as it's presumably inlined.
// If not, use runtime detection using __attribute__((ifunc))
// (see Bits.cpp)
#ifdef __POPCNT__
inline int popcount(unsigned int x) {
return __builtin_popcount(x);
}
inline int popcountll(unsigned long long x) {
return __builtin_popcountll(x);
}
#else /* !__POPCNT__ */
int popcount(unsigned int x);
int popcountll(unsigned long long x);
#endif /* !__POPCNT__ */
} // namespace detail
} // namespace folly
#endif /* FOLLY_DETAIL_BITSDETAIL_H_ */
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