[libcxx-commits] [libcxx] Replace uses of `__libcpp_ctz` by `__countr_zero` (PR #132639)

[via libcxx-commits]

https://github.com/PaulXiCao created https://github.com/llvm/llvm-project/pull/132639

Closes #131179.

>From 6fc8adf52b63a8b34d2af60645126d118b062596 Mon Sep 17 00:00:00 2001
From: Paul <paulxicao7 at gmail.com>
Date: Sun, 23 Mar 2025 23:04:38 +0100
Subject: [PATCH] replace libcpp_ctz by countr_zero

---
 libcxx/include/__algorithm/sort.h         | 4 ++--
 libcxx/include/__cxx03/__algorithm/find.h | 6 +++---
 libcxx/include/__cxx03/__algorithm/sort.h | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/libcxx/include/__algorithm/sort.h b/libcxx/include/__algorithm/sort.h
index 8dd0721f2c65f..015d6531b1d87 100644
--- a/libcxx/include/__algorithm/sort.h
+++ b/libcxx/include/__algorithm/sort.h
@@ -359,9 +359,9 @@ inline _LIBCPP_HIDE_FROM_ABI void __swap_bitmap_pos(
   // Swap one pair on each iteration as long as both bitsets have at least one
   // element for swapping.
   while (__left_bitset != 0 && __right_bitset != 0) {
-    difference_type __tz_left  = __libcpp_ctz(__left_bitset);
+    difference_type __tz_left  = __countr_zero(__left_bitset);
     __left_bitset              = __libcpp_blsr(__left_bitset);
-    difference_type __tz_right = __libcpp_ctz(__right_bitset);
+    difference_type __tz_right = __countr_zero(__right_bitset);
     __right_bitset             = __libcpp_blsr(__right_bitset);
     _Ops::iter_swap(__first + __tz_left, __last - __tz_right);
   }
diff --git a/libcxx/include/__cxx03/__algorithm/find.h b/libcxx/include/__cxx03/__algorithm/find.h
index ff5ac9b8b1bd0..29486e9438711 100644
--- a/libcxx/include/__cxx03/__algorithm/find.h
+++ b/libcxx/include/__cxx03/__algorithm/find.h
@@ -108,7 +108,7 @@ __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
     __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
     __storage_type __b     = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
     if (__b)
-      return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
+      return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
     if (__n == __dn)
       return __first + __n;
     __n -= __dn;
@@ -118,14 +118,14 @@ __find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
     if (__b)
-      return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
+      return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
   }
   // do last partial word
   if (__n > 0) {
     __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
     __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
     if (__b)
-      return _It(__first.__seg_, static_cast<unsigned>(std::__libcpp_ctz(__b)));
+      return _It(__first.__seg_, static_cast<unsigned>(std::__countr_zero(__b)));
   }
   return _It(__first.__seg_, static_cast<unsigned>(__n));
 }
diff --git a/libcxx/include/__cxx03/__algorithm/sort.h b/libcxx/include/__cxx03/__algorithm/sort.h
index 009ebf717bbd8..47472afbbe562 100644
--- a/libcxx/include/__cxx03/__algorithm/sort.h
+++ b/libcxx/include/__cxx03/__algorithm/sort.h
@@ -399,9 +399,9 @@ inline _LIBCPP_HIDE_FROM_ABI void __swap_bitmap_pos(
   // Swap one pair on each iteration as long as both bitsets have at least one
   // element for swapping.
   while (__left_bitset != 0 && __right_bitset != 0) {
-    difference_type __tz_left  = __libcpp_ctz(__left_bitset);
+    difference_type __tz_left  = __countr_zero(__left_bitset);
     __left_bitset              = __libcpp_blsr(__left_bitset);
-    difference_type __tz_right = __libcpp_ctz(__right_bitset);
+    difference_type __tz_right = __countr_zero(__right_bitset);
     __right_bitset             = __libcpp_blsr(__right_bitset);
     _Ops::iter_swap(__first + __tz_left, __last - __tz_right);
   }