Date: Sat, 25 Apr 2026 14:20:08 +0000 From: Dimitry Andric <dim@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Cc: Dimitry Andric <dimitry@andric.com> Subject: git: 821fc643b3ca - main - libcxx-compat: revert llvmorg-21-init-9130-g9e3982d9ae81: Message-ID: <69eccd98.3871d.3360220f@gitrepo.freebsd.org>
index | next in thread | raw e-mail
The branch main has been updated by dim: URL: https://cgit.FreeBSD.org/src/commit/?id=821fc643b3cad922e5438760eed9cad0d6d9b3b0 commit 821fc643b3cad922e5438760eed9cad0d6d9b3b0 Author: Dimitry Andric <dimitry@andric.com> AuthorDate: 2026-01-04 19:43:38 +0000 Commit: Dimitry Andric <dim@FreeBSD.org> CommitDate: 2026-04-25 14:14:19 +0000 libcxx-compat: revert llvmorg-21-init-9130-g9e3982d9ae81: [libc++] Replace __libcpp_{ctz, clz} with __builtin_{ctzg, clzg} (#133920) `__libcpp_{ctz, clz}` were previously used as fallbacks for `__builtin_{ctzg, clzg}` to ensure compatibility with older compilers (Clang 18 and earlier), as `__builtin_{ctzg, clzg}` became available in Clang 19. Now that support for Clang 18 has been officially dropped in #130142, we can now safely replace all instances of `__libcpp_{ctz, clz}` with `__count{l,r}_zero` (which internally call `__builtin_{ctzg, clzg}` and eliminate the fallback logic. Closes #131179. This is part of making libc++ 21 build with clang 18. PR: 292067 MFC after: 1 month --- contrib/llvm-project/libcxx/include/__bit/countl.h | 28 ++++++++++++++++++ contrib/llvm-project/libcxx/include/__bit/countr.h | 33 ++++++++++++++++++++++ 2 files changed, 61 insertions(+) diff --git a/contrib/llvm-project/libcxx/include/__bit/countl.h b/contrib/llvm-project/libcxx/include/__bit/countl.h index 075914020879..11de5f214682 100644 --- a/contrib/llvm-project/libcxx/include/__bit/countl.h +++ b/contrib/llvm-project/libcxx/include/__bit/countl.h @@ -9,6 +9,7 @@ #ifndef _LIBCPP___BIT_COUNTL_H #define _LIBCPP___BIT_COUNTL_H +#include <__bit/rotate.h> #include <__config> #include <__type_traits/integer_traits.h> #include <limits> @@ -25,7 +26,34 @@ _LIBCPP_BEGIN_NAMESPACE_STD template <class _Tp> _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int __countl_zero(_Tp __t) _NOEXCEPT { static_assert(__is_unsigned_integer_v<_Tp>, "__countl_zero requires an unsigned integer type"); +#if __has_builtin(__builtin_clzg) return __builtin_clzg(__t, numeric_limits<_Tp>::digits); +#else // __has_builtin(__builtin_clzg) + if (__t == 0) + return numeric_limits<_Tp>::digits; + + if (sizeof(_Tp) <= sizeof(unsigned int)) + return __builtin_clz(static_cast<unsigned int>(__t)) - + (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits); + else if (sizeof(_Tp) <= sizeof(unsigned long)) + return __builtin_clzl(static_cast<unsigned long>(__t)) - + (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits); + else if (sizeof(_Tp) <= sizeof(unsigned long long)) + return __builtin_clzll(static_cast<unsigned long long>(__t)) - + (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits); + else { + int __ret = 0; + int __iter = 0; + const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; + while (true) { + __t = std::__rotl(__t, __ulldigits); + if ((__iter = std::__countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits) + break; + __ret += __iter; + } + return __ret + __iter; + } +#endif // __has_builtin(__builtin_clzg) } #if _LIBCPP_STD_VER >= 20 diff --git a/contrib/llvm-project/libcxx/include/__bit/countr.h b/contrib/llvm-project/libcxx/include/__bit/countr.h index f6c98695d3d0..2179eeae9e3d 100644 --- a/contrib/llvm-project/libcxx/include/__bit/countr.h +++ b/contrib/llvm-project/libcxx/include/__bit/countr.h @@ -22,10 +22,43 @@ _LIBCPP_PUSH_MACROS _LIBCPP_BEGIN_NAMESPACE_STD +// A constexpr implementation for C++11 and later (using clang extensions for constexpr support) +// Precondition: __t != 0 (the caller __countr_zero handles __t == 0 as a special case) +template <class _Tp> +[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __countr_zero_impl(_Tp __t) _NOEXCEPT { + _LIBCPP_ASSERT_INTERNAL(__t != 0, "__countr_zero_impl called with zero value"); + static_assert(__is_unsigned_integer_v<_Tp>, "__countr_zero_impl only works with unsigned types"); + if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned int)) { + return __builtin_ctz(static_cast<unsigned int>(__t)); + } else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long)) { + return __builtin_ctzl(static_cast<unsigned long>(__t)); + } else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long long)) { + return __builtin_ctzll(static_cast<unsigned long long>(__t)); + } else { +#if _LIBCPP_STD_VER == 11 + unsigned long long __ull = static_cast<unsigned long long>(__t); + const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; + return __ull == 0ull ? __ulldigits + std::__countr_zero_impl<_Tp>(__t >> __ulldigits) : __builtin_ctzll(__ull); +#else + int __ret = 0; + const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; + while (static_cast<unsigned long long>(__t) == 0uLL) { + __ret += __ulldigits; + __t >>= __ulldigits; + } + return __ret + __builtin_ctzll(static_cast<unsigned long long>(__t)); +#endif + } +} + template <class _Tp> [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __countr_zero(_Tp __t) _NOEXCEPT { static_assert(__is_unsigned_integer_v<_Tp>, "__countr_zero only works with unsigned types"); +#if __has_builtin(__builtin_ctzg) // TODO (LLVM 21): This can be dropped once we only support Clang >= 19. return __builtin_ctzg(__t, numeric_limits<_Tp>::digits); +#else + return __t != 0 ? std::__countr_zero_impl(__t) : numeric_limits<_Tp>::digits; +#endif } #if _LIBCPP_STD_VER >= 20home | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?69eccd98.3871d.3360220f>