[libc++] Introduce __bits
It has the low-level bit fiddling operations from bit. It eliminates a cyclic dependency between __bit_reference, bits, and vector. I want to exploit this in later patches.
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D94908
GitOrigin-RevId: b973e2e2f27ede7a70d470ea537f1901759d239d
diff --git a/include/bit b/include/bit
index a0f362d..fe36017 100644
--- a/include/bit
+++ b/include/bit
@@ -55,6 +55,7 @@
*/
#include <__config>
+#include <__bits>
#include <limits>
#include <type_traits>
#include <version>
@@ -76,122 +77,6 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-#ifndef _LIBCPP_COMPILER_MSVC
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
-
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
-
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
-
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
-
-#else // _LIBCPP_COMPILER_MSVC
-
-// Precondition: __x != 0
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned __x) {
- static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
- static_assert(sizeof(unsigned long) == 4, "");
- unsigned long __where;
- if (_BitScanForward(&__where, __x))
- return static_cast<int>(__where);
- return 32;
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned long __x) {
- static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
- return __ctz(static_cast<unsigned>(__x));
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_ctz(unsigned long long __x) {
- unsigned long __where;
-#if defined(_LIBCPP_HAS_BITSCAN64)
- (defined(_M_AMD64) || defined(__x86_64__))
- if (_BitScanForward64(&__where, __x))
- return static_cast<int>(__where);
-#else
- // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
- if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
- return static_cast<int>(__where);
- if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
- return static_cast<int>(__where + 32);
-#endif
- return 64;
-}
-
-// Precondition: __x != 0
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned __x) {
- static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
- static_assert(sizeof(unsigned long) == 4, "");
- unsigned long __where;
- if (_BitScanReverse(&__where, __x))
- return static_cast<int>(31 - __where);
- return 32; // Undefined Behavior.
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned long __x) {
- static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
- return __libcpp_clz(static_cast<unsigned>(__x));
-}
-
-inline _LIBCPP_INLINE_VISIBILITY
-int __libcpp_clz(unsigned long long __x) {
- unsigned long __where;
-#if defined(_LIBCPP_HAS_BITSCAN64)
- if (_BitScanReverse64(&__where, __x))
- return static_cast<int>(63 - __where);
-#else
- // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
- if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
- return static_cast<int>(63 - (__where + 32));
- if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
- return static_cast<int>(63 - __where);
-#endif
- return 64; // Undefined Behavior.
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
- static_assert(sizeof(unsigned) == 4, "");
- return __popcnt(__x);
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
- static_assert(sizeof(unsigned long) == 4, "");
- return __popcnt(__x);
-}
-
-inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
- static_assert(sizeof(unsigned long long) == 8, "");
- return __popcnt64(__x);
-}
-
-#endif // _LIBCPP_COMPILER_MSVC
template <class _Tp>
using __bitop_unsigned_integer _LIBCPP_NODEBUG_TYPE = integral_constant<bool,