[libcxx-commits] [PATCH] D157569: Fixed issue #64544 ([libc++] std::rotl and std::rotr have the wrong signature)

[Danny via Phabricator via libcxx-commits]

DKay7 created this revision.
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- Changed parameters type int `std::rotr` and `std::rorl` functions from `unsigned int` to `int`.
- Implemented behaviour for negative parameter values.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D157569

Files:
  libcxx/include/__bit/rotate.h
  libcxx/include/bit


Index: libcxx/include/bit
===================================================================
--- libcxx/include/bit
+++ libcxx/include/bit
@@ -34,9 +34,9 @@
 
   // [bit.rotate], rotating
   template<class T>
-    constexpr T rotl(T x, unsigned int s) noexcept; // C++20
+    constexpr T rotl(T x, int s) noexcept; // C++20
   template<class T>
-    constexpr T rotr(T x, unsigned int s) noexcept; // C++20
+    constexpr T rotr(T x, int s) noexcept; // C++20
 
   // [bit.count], counting
   template<class T>
Index: libcxx/include/__bit/rotate.h
===================================================================
--- libcxx/include/__bit/rotate.h
+++ libcxx/include/__bit/rotate.h
@@ -34,15 +34,22 @@
 #if _LIBCPP_STD_VER >= 20
 
 template <__libcpp_unsigned_integer _Tp>
-[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, unsigned int __cnt) noexcept {
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, int __cnt) noexcept {
   const unsigned int __dig = numeric_limits<_Tp>::digits;
   if ((__cnt % __dig) == 0)
     return __t;
+
+  if (__cnt < 0)
+    return std::__rotr(__t, -__cnt);
+
   return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
 }
 
 template <__libcpp_unsigned_integer _Tp>
-[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, unsigned int __cnt) noexcept {
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, int __cnt) noexcept {
+  if (__cnt < 0)
+    return rotl(__t, -__cnt);
+
   return std::__rotr(__t, __cnt);
 }
 


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