[libcxx-commits] [libcxx] [libc++][numeric] P0543R3: Saturation arithmetic (PR #77967)

via libcxx-commits libcxx-commits at lists.llvm.org
Fri Jan 12 14:46:11 PST 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: Hristo Hristov (H-G-Hristov)

<details>
<summary>Changes</summary>

Implements: https://wg21.link/P0543R3
- https://eel.is/c++draft/numeric.sat

Additional references:
- Division: https://eel.is/c++draft/expr.mul#<!-- -->4
- Arithmetic conversions: https://eel.is/c++draft/expr.arith.conv#<!-- -->1
- Clang builtins: https://clang.llvm.org/docs/LanguageExtensions.html#builtin-functions

---

Patch is 39.88 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/77967.diff


23 Files Affected:

- (modified) libcxx/docs/FeatureTestMacroTable.rst (+1-1) 
- (modified) libcxx/docs/ReleaseNotes/18.rst (+4-3) 
- (modified) libcxx/docs/Status/Cxx2cPapers.csv (+1-1) 
- (modified) libcxx/include/CMakeLists.txt (+1) 
- (added) libcxx/include/__numeric/saturation_arithmetic.h (+119) 
- (modified) libcxx/include/module.modulemap.in (+1) 
- (modified) libcxx/include/numeric (+13) 
- (modified) libcxx/include/version (+1-1) 
- (modified) libcxx/modules/std/numeric.inc (+10) 
- (modified) libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.compile.pass.cpp (+5-11) 
- (modified) libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp (+5-11) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.pass.cpp (+98) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.verify.cpp (+39) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.assert.pass.cpp (+53) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.pass.cpp (+98) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.verify.cpp (+39) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/mul_sat.pass.cpp (+105) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/mul_sat.verify.cpp (+39) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/saturate_cast.pass.cpp (+109) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/saturate_cast.verify.cpp (+44) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/sub_sat.pass.cpp (+93) 
- (added) libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/sub_sat.verify.cpp (+39) 
- (modified) libcxx/utils/generate_feature_test_macro_components.py (+1-4) 


``````````diff
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 893a3b13ca06e0..9dd9c0c023bc8a 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -432,7 +432,7 @@ Status
     --------------------------------------------------- -----------------
     ``__cpp_lib_rcu``                                   *unimplemented*
     --------------------------------------------------- -----------------
-    ``__cpp_lib_saturation_arithmetic``                 *unimplemented*
+    ``__cpp_lib_saturation_arithmetic``                 ``202311L``
     --------------------------------------------------- -----------------
     ``__cpp_lib_smart_ptr_owner_equality``              *unimplemented*
     --------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst
index 6de7d07e454d34..877e387d9280fd 100644
--- a/libcxx/docs/ReleaseNotes/18.rst
+++ b/libcxx/docs/ReleaseNotes/18.rst
@@ -54,12 +54,13 @@ Implemented Papers
 - P2905R2 - Runtime format strings
 - P2918R2 - Runtime format strings II
 - P2871R3 - Remove Deprecated Unicode Conversion Facets from C++26
-- P2870R3 - Remove basic_string::reserve()
+- P2870R3 - Remove ``basic_string::reserve()``
 - P2909R4 - Fix formatting of code units as integers (Dude, where’s my ``char``?)
-- P2821R5 - span.at()
-- P0521R0 - Proposed Resolution for CA 14 (shared_ptr use_count/unique)
+- P2821R5 - ``span.at()``
+- P0521R0 - Proposed Resolution for CA 14 (``shared_ptr`` ``use_count/unique``)
 - P1759R6 - Native handles and file streams
 - P2517R1 - Add a conditional ``noexcept`` specification to ``std::apply``
+- P0543R3 - Saturation arithmetic
 
 
 Improvements and New Features
diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index 5701717f39766c..b38b3028863fee 100644
--- a/libcxx/docs/Status/Cxx2cPapers.csv
+++ b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -27,7 +27,7 @@
 "`P2714R1 <https://wg21.link/P2714R1>`__","LWG","Bind front and back to NTTP callables","Varna June 2023","","",""
 "`P2630R4 <https://wg21.link/P2630R4>`__","LWG","``submdspan``","Varna June 2023","","",""
 "","","","","","",""
-"`P0543R3 <https://wg21.link/P0543R3>`__","LWG","Saturation arithmetic","Kona November 2023","","",""
+"`P0543R3 <https://wg21.link/P0543R3>`__","LWG","Saturation arithmetic","Kona November 2023","|Complete|","18.0",""
 "`P2407R5 <https://wg21.link/P2407R5>`__","LWG","Freestanding Library: Partial Classes","Kona November 2023","","",""
 "`P2546R5 <https://wg21.link/P2546R5>`__","LWG","Debugging Support","Kona November 2023","","",""
 "`P2905R2 <https://wg21.link/P2905R2>`__","LWG","Runtime format strings","Kona November 2023","|Complete|","18.0","|format| |DR|"
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 0fe3ab44d2466e..c4d8a9f092de14 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -569,6 +569,7 @@ set(files
   __numeric/pstl_reduce.h
   __numeric/pstl_transform_reduce.h
   __numeric/reduce.h
+  __numeric/saturation_arithmetic.h
   __numeric/transform_exclusive_scan.h
   __numeric/transform_inclusive_scan.h
   __numeric/transform_reduce.h
diff --git a/libcxx/include/__numeric/saturation_arithmetic.h b/libcxx/include/__numeric/saturation_arithmetic.h
new file mode 100644
index 00000000000000..6d13ec5b3fd5bc
--- /dev/null
+++ b/libcxx/include/__numeric/saturation_arithmetic.h
@@ -0,0 +1,119 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
+#define _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
+
+#include <__concepts/arithmetic.h>
+#include <__config>
+#include <__type_traits/decay.h>
+#include <__utility/cmp.h>
+#include <limits>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 26
+
+template <typename _Tp>
+concept __libcpp_standard_integer = __libcpp_unsigned_integer<decay_t<_Tp>> || __libcpp_signed_integer<decay_t<_Tp>>;
+
+template <__libcpp_standard_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp add_sat(_Tp __x, _Tp __y) noexcept {
+  if (_Tp __sum; !__builtin_add_overflow(__x, __y, &__sum))
+    return __sum;
+  // Handle overflow
+  if constexpr (__libcpp_unsigned_integer<_Tp>) {
+    return std::numeric_limits<_Tp>::max();
+  } else {
+    // Signed addition overflow
+    if (__x > 0)
+      // Overflows if (x > 0 && y > 0)
+      return std::numeric_limits<_Tp>::max();
+    else
+      // Overflows if  (x < 0 && y < 0)
+      return std::numeric_limits<_Tp>::min();
+  }
+}
+
+template <__libcpp_standard_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp sub_sat(_Tp __x, _Tp __y) noexcept {
+  if (_Tp __sub; !__builtin_sub_overflow(__x, __y, &__sub))
+    return __sub;
+  // Handle overflow
+  if constexpr (__libcpp_unsigned_integer<_Tp>) {
+    // Overflows if (x < y)
+    return std::numeric_limits<_Tp>::min();
+  } else {
+    // Signed subtration overflow
+    if (__x > 0)
+      // Overflows if (x > 0 && y < 0)
+      return std::numeric_limits<_Tp>::max();
+    else
+      // Overflows if (x < 0 && y > 0)
+      return std::numeric_limits<_Tp>::min();
+  }
+}
+
+template <__libcpp_standard_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp mul_sat(_Tp __x, _Tp __y) noexcept {
+  if (_Tp __mul; !__builtin_mul_overflow(__x, __y, &__mul))
+    return __mul;
+  // Handle overflow
+  if constexpr (__libcpp_unsigned_integer<_Tp>) {
+    return std::numeric_limits<_Tp>::max();
+  } else {
+    // Signed multiplication overflow
+    if (__x > 0) {
+      if (__y > 0)
+        // Overflows if (x > 0 && y > 0)
+        return std::numeric_limits<_Tp>::max();
+      // Overflows if (x > 0 && y < 0)
+      return std::numeric_limits<_Tp>::min();
+    }
+    if (__y > 0)
+      // Overflows if (x < 0 && y > 0)
+      return std::numeric_limits<_Tp>::min();
+    // Overflows if (x < 0 && y < 0)
+    return std::numeric_limits<_Tp>::max();
+  }
+}
+
+template <__libcpp_standard_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp div_sat(_Tp __x, _Tp __y) noexcept {
+  _LIBCPP_ASSERT_UNCATEGORIZED(__y != 0, "Division by 0 is undefined");
+  if constexpr (__libcpp_unsigned_integer<_Tp>) {
+    return __x / __y;
+  } else {
+    // Handle signed division overflow
+    if (__x == std::numeric_limits<_Tp>::min() && __y == _Tp{-1})
+      return std::numeric_limits<_Tp>::max();
+    return __x / __y;
+  }
+}
+
+template <__libcpp_standard_integer _Rp, __libcpp_standard_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Rp saturate_cast(_Tp __x) noexcept {
+  // Handle overflow
+  if (std::cmp_less_equal(__x, std::numeric_limits<_Rp>::min()))
+    return std::numeric_limits<_Rp>::min();
+  if (std::cmp_greater_equal(__x, std::numeric_limits<_Rp>::max()))
+    return std::numeric_limits<_Rp>::max();
+  // No overflow
+  return static_cast<_Rp>(__x);
+}
+
+#endif // _LIBCPP_STD_VER >= 26
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index d10670d4faaffc..194a74a1e07b14 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1580,6 +1580,7 @@ module std_private_numeric_pstl_transform_reduce    [system] {
   export *
 }
 module std_private_numeric_reduce                   [system] { header "__numeric/reduce.h" }
+module std_private_numeric_saturation_arithmetic    [system] { header "__numeric/saturation_arithmetic.h" }
 module std_private_numeric_transform_exclusive_scan [system] { header "__numeric/transform_exclusive_scan.h" }
 module std_private_numeric_transform_inclusive_scan [system] { header "__numeric/transform_inclusive_scan.h" }
 module std_private_numeric_transform_reduce         [system] { header "__numeric/transform_reduce.h" }
diff --git a/libcxx/include/numeric b/libcxx/include/numeric
index d09d0a81fcc03a..0fe7115f1c666e 100644
--- a/libcxx/include/numeric
+++ b/libcxx/include/numeric
@@ -140,6 +140,18 @@ template<class T>
 template<class T>
     constexpr T* midpoint(T* a, T* b);        // C++20
 
+// [numeric.sat], saturation arithmetic
+template<class T>
+constexpr T add_sat(T x, T y) noexcept;                     // freestanding, Since C++26
+template<class T>
+constexpr T sub_sat(T x, T y) noexcept;                     // freestanding, Since C++26
+template<class T>
+constexpr T mul_sat(T x, T y) noexcept;                     // freestanding, Since C++26
+template<class T>
+constexpr T div_sat(T x, T y) noexcept;                     // freestanding, Since C++26
+template<class T, class U>
+constexpr T saturate_cast(U x) noexcept;                    // freestanding, Since C++26
+
 }  // std
 
 */
@@ -160,6 +172,7 @@ template<class T>
 #include <__numeric/pstl_reduce.h>
 #include <__numeric/pstl_transform_reduce.h>
 #include <__numeric/reduce.h>
+#include <__numeric/saturation_arithmetic.h>
 #include <__numeric/transform_exclusive_scan.h>
 #include <__numeric/transform_inclusive_scan.h>
 #include <__numeric/transform_reduce.h>
diff --git a/libcxx/include/version b/libcxx/include/version
index c96647894dce63..b8d0c4e6f3c898 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -504,7 +504,7 @@ __cpp_lib_within_lifetime                               202306L <type_traits>
 // # define __cpp_lib_out_ptr                              202311L
 # define __cpp_lib_ratio                                202306L
 // # define __cpp_lib_rcu                                  202306L
-// # define __cpp_lib_saturation_arithmetic                202311L
+# define __cpp_lib_saturation_arithmetic                202311L
 // # define __cpp_lib_smart_ptr_owner_equality             202306L
 # define __cpp_lib_span_at                              202311L
 // # define __cpp_lib_span_initializer_list                202311L
diff --git a/libcxx/modules/std/numeric.inc b/libcxx/modules/std/numeric.inc
index d2b7688d4e5f10..3bc7b231681584 100644
--- a/libcxx/modules/std/numeric.inc
+++ b/libcxx/modules/std/numeric.inc
@@ -54,4 +54,14 @@ export namespace std {
 
   // [numeric.ops.midpoint], midpoint
   using std::midpoint;
+
+#if _LIBCPP_STD_VER >= 26
+  // [numeric.sat], saturation arithmetic
+  using std::add_sat;
+  using std::div_sat;
+  using std::mul_sat;
+  using std::saturate_cast;
+  using std::sub_sat;
+#endif
+
 } // namespace std
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.compile.pass.cpp
index b510eefc69a5d3..d132b7c7b9c4f5 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.compile.pass.cpp
@@ -263,17 +263,11 @@
 #   endif
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_saturation_arithmetic
-#     error "__cpp_lib_saturation_arithmetic should be defined in c++26"
-#   endif
-#   if __cpp_lib_saturation_arithmetic != 202311L
-#     error "__cpp_lib_saturation_arithmetic should have the value 202311L in c++26"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_saturation_arithmetic
-#     error "__cpp_lib_saturation_arithmetic should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_saturation_arithmetic
+#   error "__cpp_lib_saturation_arithmetic should be defined in c++26"
+# endif
+# if __cpp_lib_saturation_arithmetic != 202311L
+#   error "__cpp_lib_saturation_arithmetic should have the value 202311L in c++26"
 # endif
 
 #endif // TEST_STD_VER > 23
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index d5a0839b30f824..edb36da28bbe15 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -7167,17 +7167,11 @@
 #   error "__cpp_lib_sample should have the value 201603L in c++26"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_saturation_arithmetic
-#     error "__cpp_lib_saturation_arithmetic should be defined in c++26"
-#   endif
-#   if __cpp_lib_saturation_arithmetic != 202311L
-#     error "__cpp_lib_saturation_arithmetic should have the value 202311L in c++26"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_saturation_arithmetic
-#     error "__cpp_lib_saturation_arithmetic should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_saturation_arithmetic
+#   error "__cpp_lib_saturation_arithmetic should be defined in c++26"
+# endif
+# if __cpp_lib_saturation_arithmetic != 202311L
+#   error "__cpp_lib_saturation_arithmetic should have the value 202311L in c++26"
 # endif
 
 # ifndef __cpp_lib_scoped_lock
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.pass.cpp
new file mode 100644
index 00000000000000..ccd3594fd3a652
--- /dev/null
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.pass.cpp
@@ -0,0 +1,98 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+
+// <numeric>
+
+// template<class T>
+// constexpr T add_sat(T x, T y) noexcept;                     // freestanding
+
+#include <cassert>
+#include <concepts>
+#include <limits>
+#include <numeric>
+
+template <typename IntegerT>
+constexpr bool test_signed() {
+  constexpr auto minVal = std::numeric_limits<IntegerT>::min();
+  constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
+
+  static_assert(noexcept(std::div_sat(minVal, maxVal)));
+
+  // No saturation
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(IntegerT{3}, IntegerT{4});
+    assert(sum == IntegerT{7});
+  }
+
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(IntegerT{-3}, IntegerT{4});
+    assert(sum == IntegerT{1});
+  }
+
+  // Saturation - max - both arguments positive
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(maxVal, IntegerT{4});
+    assert(sum == maxVal);
+  }
+
+  // Saturation - min - both arguments negative
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(minVal, IntegerT{-4});
+    assert(sum == minVal);
+  }
+
+  return true;
+}
+
+template <typename IntegerT>
+constexpr bool test_unsigned() {
+  constexpr auto minVal = std::numeric_limits<IntegerT>::min();
+  constexpr auto maxVal = std::numeric_limits<IntegerT>::max();
+
+  static_assert(noexcept(std::div_sat(minVal, maxVal)));
+
+  // No Saturation
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(IntegerT{3}, IntegerT{4});
+    assert(sum == IntegerT{7});
+  }
+
+  // Saturation - max only
+  {
+    std::same_as<IntegerT> decltype(auto) sum = std::add_sat(maxVal, IntegerT{4});
+    assert(sum == maxVal);
+  }
+
+  return true;
+}
+
+constexpr bool test() {
+  // Signed
+  test_signed<signed char>();
+  test_signed<short int>();
+  test_signed<int>();
+  test_signed<long int>();
+  test_signed<long long int>();
+  // Unsigned
+  test_unsigned<unsigned char>();
+  test_unsigned<unsigned short int>();
+  test_unsigned<unsigned int>();
+  test_unsigned<unsigned long int>();
+  test_unsigned<unsigned long long int>();
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.verify.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.verify.cpp
new file mode 100644
index 00000000000000..b05b30abea6fdb
--- /dev/null
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/add_sat.verify.cpp
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+
+// <numeric>
+
+// template<class T>
+// constexpr T add_sat(T x, T y) noexcept;                     // freestanding
+
+#include <cstdint>
+#include <numeric>
+
+#include "test_macros.h"
+
+template <typename IntegerT>
+constexpr void test_constraint() {
+  // expected-error-re@*:* 0-2 {{constant expression evaluates to {{.*}} which cannot be narrowed to type {{.*}}}}
+  // expected-error@*:* 0-3 {{no matching function for call to 'add_sat'}}
+  // expected-error@*:* 0-2 {{expected unqualified-id}}
+  [[maybe_unused]] auto sum = std::add_sat(IntegerT{3}, IntegerT{4});
+}
+
+constexpr bool test() {
+  test_constraint<bool>();
+  test_constraint<char>();
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+  test_constraint<wchar_t>();
+#endif
+  test_constraint<std::char16_t>();
+  test_constraint<std::char32_t>();
+
+  return true;
+}
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.assert.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.assert.pass.cpp
new file mode 100644
index 00000000000000..98616d2c1c427c
--- /dev/null
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.assert.pass.cpp
@@ -0,0 +1,53 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+
+// REQUIRES: has-unix-headers
+// REQUIRES: libcpp-hardening-mode={{extensive|debug}}
+// XFAIL: availability-verbose_abort-missing
+
+// <numeric>
+
+// template<class T>
+// constexpr T div_sat(T x, T y) noexcept;                     // freestanding
+
+#include <cassert>
+#include <concepts>
+#include <limits>
+#include <numeric>
+
+#include "check_assertion.h"
+
+template <typename IntegerT>
+constexpr void test() {
+  TEST_LIBCPP_ASSERT_FAILURE((void)std::div_sat(IntegerT{3}, IntegerT{0}), "Division by 0 is undefined");
+}
+
+constexpr bool test() {
+  // signed
+  test<signed char>();
+  test<short int>();
+  test<int>();
+  test<long int>();
+  test<long long int>();
+  // unsigned
+  test<unsigned char>();
+  test<unsigned short int>();
+  test<unsigned int>();
+  test<unsigned long int>();
+  test<unsigned long long int>();
+
+  return true;
+}
+
+int main(int, char**) {
+  assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.pass.cpp
new file mode 100644
index 00000000000000..d2891f77c564fa
--- /dev/null
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.sat/div_sat.pass.cpp
@@ -0,0 +1,98 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===--------------------------------------------------...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/77967


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