[libcxx-commits] [libcxx] [libc++][NFC] Reuse `__bit_log2` for `sort` (PR #135303)

[A. Jiang via libcxx-commits]

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@@ -878,7 +861,8 @@ template <class _AlgPolicy, class _RandomAccessIterator, class _Comp>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
 __sort_dispatch(_RandomAccessIterator __first, _RandomAccessIterator __last, _Comp& __comp) {
   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
-  difference_type __depth_limit = 2 * std::__log2i(__last - __first);
+  difference_type __depth_limit = static_cast<difference_type>(
+      2 * std::__bit_log2(static_cast<__make_unsigned_t<difference_type> >(__last - __first)));
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frederick-vs-ja wrote:

Oh, thanks! I was confused by the _`to-unsigned-like`_ in the standard wording which only is present since C++20.

https://github.com/llvm/llvm-project/pull/135303