clang/lib/Headers/lzcntintrin.h

/*===---- lzcntintrin.h - LZCNT intrinsics ---------------------------------===
 *
 * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 * See https://llvm.org/LICENSE.txt for license information.
 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 *
 *===-----------------------------------------------------------------------===
 */

#if !defined __X86INTRIN_H && !defined __IMMINTRIN_H
#error "Never use <lzcntintrin.h> directly; include <x86intrin.h> instead."
#endif

#ifndef __LZCNTINTRIN_H
#define __LZCNTINTRIN_H

/* Define the default attributes for the functions in this file.
   Allow using the lzcnt intrinsics even for non-LZCNT targets. Since the LZCNT
   intrinsics are mapped to llvm.ctlz.*, false, which can be lowered to BSR on
   non-LZCNT targets with zero-value input handled correctly. */
#if defined(__cplusplus) && (__cplusplus >= 201103L)
#define __DEFAULT_FN_ATTRS                                                     \
  __attribute__((__always_inline__, __nodebug__)) constexpr
#else
#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__))
#endif

#ifndef _MSC_VER
/// Counts the number of leading zero bits in the operand.
///
/// \headerfile <x86intrin.h>
///
/// This intrinsic corresponds to the \c LZCNT instruction.
///
/// \param __X
///    An unsigned 16-bit integer whose leading zeros are to be counted.
/// \returns An unsigned 16-bit integer containing the number of leading zero
///    bits in the operand.
#define __lzcnt16(X) __builtin_ia32_lzcnt_u16((unsigned short)(X))
#endif // _MSC_VER

/// Counts the number of leading zero bits in the operand.
///
/// \headerfile <x86intrin.h>
///
/// This intrinsic corresponds to the \c LZCNT instruction.
///
/// \param __X
///    An unsigned 32-bit integer whose leading zeros are to be counted.
/// \returns An unsigned 32-bit integer containing the number of leading zero
///    bits in the operand.
/// \see _lzcnt_u32
static __inline__ unsigned int __DEFAULT_FN_ATTRS
__lzcnt32(unsigned int __X) {
  return __builtin_ia32_lzcnt_u32(__X);
}

/// Counts the number of leading zero bits in the operand.
///
/// \headerfile <x86intrin.h>
///
/// This intrinsic corresponds to the \c LZCNT instruction.
///
/// \param __X
///    An unsigned 32-bit integer whose leading zeros are to be counted.
/// \returns An unsigned 32-bit integer containing the number of leading zero
///    bits in the operand.
/// \see __lzcnt32
static __inline__ unsigned int __DEFAULT_FN_ATTRS
_lzcnt_u32(unsigned int __X) {
  return __builtin_ia32_lzcnt_u32(__X);
}

#ifdef __x86_64__
#ifndef _MSC_VER
/// Counts the number of leading zero bits in the operand.
///
/// \headerfile <x86intrin.h>
///
/// This intrinsic corresponds to the \c LZCNT instruction.
///
/// \param __X
///    An unsigned 64-bit integer whose leading zeros are to be counted.
/// \returns An unsigned 64-bit integer containing the number of leading zero
///    bits in the operand.
/// \see _lzcnt_u64
#define __lzcnt64(X) __builtin_ia32_lzcnt_u64((unsigned long long)(X))
#endif // _MSC_VER

/// Counts the number of leading zero bits in the operand.
///
/// \headerfile <x86intrin.h>
///
/// This intrinsic corresponds to the \c LZCNT instruction.
///
/// \param __X
///    An unsigned 64-bit integer whose leading zeros are to be counted.
/// \returns An unsigned 64-bit integer containing the number of leading zero
///    bits in the operand.
/// \see __lzcnt64
static __inline__ unsigned long long __DEFAULT_FN_ATTRS
_lzcnt_u64(unsigned long long __X) {
  return __builtin_ia32_lzcnt_u64(__X);
}
#endif

#undef __DEFAULT_FN_ATTRS

#endif /* __LZCNTINTRIN_H */