On Fri, 16 Jan 2026 at 08:28, Soumya AR <[email protected]> wrote:
> >> +// This file is part of the GNU ISO C++ Library. This library is free
> >> +// software; you can redistribute it and/or modify it under the
> >> +// terms of the GNU General Public License as published by the
> >> +// Free Software Foundation; either version 3, or (at your option)
> >> +// any later version.
> >> +
> >> +// This library is distributed in the hope that it will be useful,
> >> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >> +// GNU General Public License for more details.
> >> +
> >> +// Under Section 7 of GPL version 3, you are granted additional
> >> +// permissions described in the GCC Runtime Library Exception, version
> >> +// 3.1, as published by the Free Software Foundation.
> >> +
> >> +// You should have received a copy of the GNU General Public License and
> >> +// a copy of the GCC Runtime Library Exception along with this program;
> >> +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
> >> +// <http://www.gnu.org/licenses/>.
> >> +
> >> +// { dg-do run { target c++26 } }
> >
> > Do these new tests need { dg-add-options libatomic } ? I think they
> > probably do.
> >
> > What about { dg-require-atomic-cmpxchg-word "" } ?
>
> Yes, you're right, ideally should have both directives.
>
> However, on re-working this patch, I don't think these tests are needed in
> libstdc++ at all. I already have correctness tests for the builtins in the
> GCC testsuite.
>
> To test the API, I've created a C++26 version of nonmembers.cc for
> fetch_min/max.
> And another fetch_min/max version for the correctness tests for atomic_ref.
I missed this part, sorry.
I think the new tests make sense in libstdc++. The builtins might be
thouroughly tested in the compiler tests, but having library tests
ensures we don't make a silly mistake like calling __atomic_fetch_min
from the fetch_max function (an easy copy*paste error to make when
refactoring).
The tests in the new patch are adequate for that purpose: each
function is called at least once and the expected result is verified.
> Or for both of these, should we just update the existing tests to C++26?
I think it's better to have separate tests for the new members,
because the existing tests are typically only run for the default -std
mode (currently gnu++20) and so would not test any parts of the file
guarded by #if __cpp_lib_atomic_min_max. Having a separate test with {
target c++26 } means that everybody who runs the testsuite will run
that test.
And we don't want to add { target c++26 } to the existing tests,
because then we would not test that the C++11 features still work in
C++11.
> What about c_compat.cc?
No changes to that file, because there should be no changes to <stdatomic.h>
>
> Thanks,
> Soumya
>
> >> +#include <atomic>
> >> +#include <limits>
> >> +#include <testsuite_hooks.h>
> >> +
> >> +template<typename T>
> >> +void test_signed()
> >> +{
> >> + std::atomic<T> a;
> >> + const std::memory_order mo = std::memory_order_relaxed;
> >> + T expected = 0;
> >> + T value = 0;
> >> +
> >> + a.store(100);
> >> + value = a.fetch_min(50);
> >> + VERIFY( value == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_min(75, mo);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_min(25);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 25 );
> >> +
> >> + a.store(-10);
> >> + value = a.fetch_min(-20);
> >> + VERIFY( value == -10 );
> >> + VERIFY( a.load() == -20 );
> >> +
> >> + value = a.fetch_min(-5, mo);
> >> + VERIFY( value == -20 );
> >> + VERIFY( a.load() == -20 );
> >> +
> >> + a.store(10);
> >> + value = a.fetch_min(-5);
> >> + VERIFY( value == 10 );
> >> + VERIFY( a.load() == -5 );
> >> +
> >> + a.store(20);
> >> + value = a.fetch_max(50);
> >> + VERIFY( value == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_max(30, mo);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_max(100);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 100 );
> >> +
> >> + a.store(-50);
> >> + value = a.fetch_max(-20);
> >> + VERIFY( value == -50 );
> >> + VERIFY( a.load() == -20 );
> >> +
> >> + value = a.fetch_max(-10, mo);
> >> + VERIFY( value == -20 );
> >> + VERIFY( a.load() == -10 );
> >> +
> >> + a.store(-10);
> >> + value = a.fetch_max(5);
> >> + VERIFY( value == -10 );
> >> + VERIFY( a.load() == 5 );
> >> +
> >> + T min_val = std::numeric_limits<T>::min();
> >> + T max_val = std::numeric_limits<T>::max();
> >> +
> >> + a.store(0);
> >> + value = a.fetch_min(min_val);
> >> + VERIFY( value == 0 );
> >> + VERIFY( a.load() == min_val );
> >> +
> >> + a.store(0);
> >> + value = a.fetch_max(max_val);
> >> + VERIFY( value == 0 );
> >> + VERIFY( a.load() == max_val );
> >> +}
> >> +
> >> +template<typename T>
> >> +void test_unsigned()
> >> +{
> >> + std::atomic<T> a;
> >> + const std::memory_order mo = std::memory_order_relaxed;
> >> + T expected = 0;
> >> + T value = 0;
> >> +
> >> + a.store(100);
> >> + value = a.fetch_min(50);
> >> + VERIFY( value == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_min(75, mo);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_min(25);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 25 );
> >> +
> >> + a.store(20);
> >> + value = a.fetch_max(50);
> >> + VERIFY( value == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_max(30, mo);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + value = a.fetch_max(100);
> >> + VERIFY( value == 50 );
> >> + VERIFY( a.load() == 100 );
> >> +
> >> + T min_val = std::numeric_limits<T>::min();
> >> + T max_val = std::numeric_limits<T>::max();
> >> +
> >> + a.store(10);
> >> + value = a.fetch_min(min_val);
> >> + VERIFY( value == 10 );
> >> + VERIFY( a.load() == min_val );
> >> +
> >> + a.store(10);
> >> + value = a.fetch_max(max_val);
> >> + VERIFY( value == 10 );
> >> + VERIFY( a.load() == max_val );
> >> +}
> >> +
> >> +int main()
> >> +{
> >> + test_signed<signed char>();
> >> + test_signed<short>();
> >> + test_signed<int>();
> >> + test_signed<long>();
> >> + test_signed<long long>();
> >> +
> >> + test_unsigned<unsigned char>();
> >> + test_unsigned<unsigned short>();
> >> + test_unsigned<unsigned int>();
> >> + test_unsigned<unsigned long>();
> >> + test_unsigned<unsigned long long>();
> >> +
> >> + return 0;
> >> +}
> >> \ No newline at end of file
> >> diff --git
> >> a/libstdc++-v3/testsuite/29_atomics/atomic_integral/fetch_minmax_order.cc
> >> b/libstdc++-v3/testsuite/29_atomics/atomic_integral/fetch_minmax_order.cc
> >> new file mode 100644
> >> index 00000000000..3ed6f2e2e6f
> >> --- /dev/null
> >> +++
> >> b/libstdc++-v3/testsuite/29_atomics/atomic_integral/fetch_minmax_order.cc
> >> @@ -0,0 +1,116 @@
> >> +// Copyright The GNU Toolchain Authors.
> >> +//
> >> +// This file is part of the GNU ISO C++ Library. This library is free
> >> +// software; you can redistribute it and/or modify it under the
> >> +// terms of the GNU General Public License as published by the
> >> +// Free Software Foundation; either version 3, or (at your option)
> >> +// any later version.
> >> +
> >> +// This library is distributed in the hope that it will be useful,
> >> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >> +// GNU General Public License for more details.
> >> +
> >> +// Under Section 7 of GPL version 3, you are granted additional
> >> +// permissions described in the GCC Runtime Library Exception, version
> >> +// 3.1, as published by the Free Software Foundation.
> >> +
> >> +// You should have received a copy of the GNU General Public License and
> >> +// a copy of the GCC Runtime Library Exception along with this program;
> >> +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
> >> +// <http://www.gnu.org/licenses/>.
> >> +
> >> +// { dg-do run { target c++26 } }
> >> +
> >> +#include <atomic>
> >> +#include <testsuite_hooks.h>
> >> +
> >> +void test_memory_orderings()
> >> +{
> >> + std::atomic<int> a;
> >> + int v;
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_relaxed);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load(std::memory_order_relaxed) == 50 );
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_consume);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_acquire);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_release);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_acq_rel);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(100);
> >> + v = a.fetch_min(50, std::memory_order_seq_cst);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_relaxed);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load(std::memory_order_relaxed) == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_consume);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_acquire);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_release);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_acq_rel);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +
> >> + a.store(20);
> >> + v = a.fetch_max(50, std::memory_order_seq_cst);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a.load() == 50 );
> >> +}
> >> +
> >> +// Test volatile atomic operations
> >> +void test_volatile()
> >> +{
> >> + volatile std::atomic<int> va;
> >> + int v;
> >> +
> >> + va.store(100);
> >> + v = va.fetch_min(50);
> >> + VERIFY( v == 100 );
> >> + VERIFY( va.load() == 50 );
> >> +
> >> + va.store(20);
> >> + v = va.fetch_max(50, std::memory_order_relaxed);
> >> + VERIFY( v == 20 );
> >> + VERIFY( va.load() == 50 );
> >> +}
> >> +
> >> +int main()
> >> +{
> >> + test_memory_orderings();
> >> + test_volatile();
> >> + return 0;
> >> +}
> >> \ No newline at end of file
> >> diff --git
> >> a/libstdc++-v3/testsuite/29_atomics/atomic_integral/nonmembers.cc
> >> b/libstdc++-v3/testsuite/29_atomics/atomic_integral/nonmembers.cc
> >> index a07d9700ff4..3fb86db65b1 100644
> >> --- a/libstdc++-v3/testsuite/29_atomics/atomic_integral/nonmembers.cc
> >> +++ b/libstdc++-v3/testsuite/29_atomics/atomic_integral/nonmembers.cc
> >> @@ -111,6 +111,22 @@ test01()
> >> static_assert( std::is_same<decltype(r37), int>::value, "" );
> >> auto r38 = atomic_fetch_xor_explicit(&a, l, mo);
> >> static_assert( std::is_same<decltype(r38), long>::value, "" );
> >> + auto r39 = atomic_fetch_min(&v, i);
> >> + static_assert( std::is_same<decltype(r39), int>::value, "" );
> >> + auto r40 = atomic_fetch_min(&a, l);
> >> + static_assert( std::is_same<decltype(r40), long>::value, "" );
> >> + auto r41 = atomic_fetch_min_explicit(&v, i, mo);
> >> + static_assert( std::is_same<decltype(r41), int>::value, "" );
> >> + auto r42 = atomic_fetch_min_explicit(&a, l, mo);
> >> + static_assert( std::is_same<decltype(r42), long>::value, "" );
> >> + auto r43 = atomic_fetch_max(&v, i);
> >> + static_assert( std::is_same<decltype(r43), int>::value, "" );
> >> + auto r44 = atomic_fetch_max(&a, l);
> >> + static_assert( std::is_same<decltype(r44), long>::value, "" );
> >> + auto r45 = atomic_fetch_max_explicit(&v, i, mo);
> >> + static_assert( std::is_same<decltype(r45), int>::value, "" );
> >> + auto r46 = atomic_fetch_max_explicit(&a, l, mo);
> >> + static_assert( std::is_same<decltype(r46), long>::value, "" );
> >> }
> >>
> >> void
> >> @@ -160,4 +176,12 @@ test02()
> >> atomic_fetch_xor(&a, i);
> >> atomic_fetch_xor_explicit(&v, i, mo);
> >> atomic_fetch_xor_explicit(&a, i, mo);
> >> + atomic_fetch_min(&v, i);
> >> + atomic_fetch_min(&a, i);
> >> + atomic_fetch_min_explicit(&v, i, mo);
> >> + atomic_fetch_min_explicit(&a, i, mo);
> >> + atomic_fetch_max(&v, i);
> >> + atomic_fetch_max(&a, i);
> >> + atomic_fetch_max_explicit(&v, i, mo);
> >> + atomic_fetch_max_explicit(&a, i, mo);
> >> }
> >> diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_ref/integral.cc
> >> b/libstdc++-v3/testsuite/29_atomics/atomic_ref/integral.cc
> >> index 310434cefb5..5a282320bd7 100644
> >> --- a/libstdc++-v3/testsuite/29_atomics/atomic_ref/integral.cc
> >> +++ b/libstdc++-v3/testsuite/29_atomics/atomic_ref/integral.cc
> >> @@ -155,9 +155,38 @@ test01()
> >> v = a ^= 0x121;
> >> VERIFY( v == 0x022 );
> >> VERIFY( a == 0x022 );
> >> +
> >> +
> >> + a = 100;
> >> + v = a.fetch_min(50);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a == 50 );
> >> +
> >> + v = a.fetch_min(75, mo);
> >> + VERIFY( v == 50 );
> >> + VERIFY( a == 50 );
> >> +
> >> + a = -10;
> >> + v = a.fetch_min(-20);
> >> + VERIFY( v == -10 );
> >> + VERIFY( a == -20 );
> >> +
> >> + a = 20;
> >> + v = a.fetch_max(50);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a == 50 );
> >> +
> >> + v = a.fetch_max(30, mo);
> >> + VERIFY( v == 50 );
> >> + VERIFY( a == 50 );
> >> +
> >> + a = -50;
> >> + v = a.fetch_max(-20);
> >> + VERIFY( v == -50 );
> >> + VERIFY( a == -20 );
> >> }
> >>
> >> - VERIFY( value == 0x022 );
> >> + VERIFY( value == -20 );
> >> }
> >>
> >> void
> >> @@ -292,9 +321,27 @@ test02()
> >> v = a ^= 0x12;
> >> VERIFY( v == 0x24 );
> >> VERIFY( a == 0x24 );
> >> +
> >> + a = 100;
> >> + v = a.fetch_min(50);
> >> + VERIFY( v == 100 );
> >> + VERIFY( a == 50 );
> >> +
> >> + v = a.fetch_min(75, mo);
> >> + VERIFY( v == 50 );
> >> + VERIFY( a == 50 );
> >> +
> >> + a = 20;
> >> + v = a.fetch_max(50);
> >> + VERIFY( v == 20 );
> >> + VERIFY( a == 50 );
> >> +
> >> + v = a.fetch_max(30, mo);
> >> + VERIFY( v == 50 );
> >> + VERIFY( a == 50 );
> >> }
> >>
> >> - VERIFY( value == 0x24 );
> >> + VERIFY( value == 50 );
> >> }
> >> void
> >> test03()
> >> diff --git
> >> a/libstdc++-v3/testsuite/29_atomics/headers/stdatomic.h/c_compat.cc
> >> b/libstdc++-v3/testsuite/29_atomics/headers/stdatomic.h/c_compat.cc
> >> index bcdb969b0c0..2e4c73c456c 100644
> >> --- a/libstdc++-v3/testsuite/29_atomics/headers/stdatomic.h/c_compat.cc
> >> +++ b/libstdc++-v3/testsuite/29_atomics/headers/stdatomic.h/c_compat.cc
> >> @@ -131,6 +131,10 @@ static_assert( requires (::atomic_int* i, int* e) {
> >> ::atomic_fetch_or_explicit(i, 1, memory_order_relaxed);
> >> ::atomic_fetch_xor(i, 1);
> >> ::atomic_fetch_xor_explicit(i, 1, memory_order_relaxed);
> >> + ::atomic_fetch_min(i, 1);
> >> + ::atomic_fetch_min_explicit(i, 1, memory_order_relaxed);
> >> + ::atomic_fetch_max(i, 1);
> >> + ::atomic_fetch_max_explicit(i, 1, memory_order_relaxed);
> >> } );
> >>
> >> static_assert( requires (::atomic_flag* f) {
> >> --
> >> 2.44.0
