[libcxx-commits] [libcxx] [libcxx][algorithm] Optimize std::stable_sort via radix sort algorithm (PR #104683)

[Nikolas Klauser via libcxx-commits]

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=?utf-8?b?0JTQvNC40YLRgNC40Lkg0JjQtw=?Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/104683 at github.com>


================
@@ -20,14 +20,15 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 14
 
-template <__libcpp_unsigned_integer _Tp>
+template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_log2(_Tp __t) noexcept {
-  return numeric_limits<_Tp>::digits - 1 - std::countl_zero(__t);
+  static_assert(is_unsigned<_Tp>::value, "__bit_log2 requires an unsigned integer type");
----------------
philnik777 wrote:

I think we want to use `__libcpp_is_unsigned_integer` here instead just to avoid any behaviour change in this patch. (I'm not sure whether using `is_unsigned` results in one)

https://github.com/llvm/llvm-project/pull/104683