On 7/9/25 14:43, Jonathan Wakely wrote:
On Thu, 3 Jul 2025 at 11:35, Luc Grosheintz <luc.groshei...@gmail.com> wrote:This commit implements and tests the function is_sufficiently_aligned from P2897R7. libstdc++-v3/ChangeLog: * include/bits/align.h (is_sufficiently_aligned): New function. * include/bits/version.def (is_sufficiently_aligned): Add. * include/bits/version.h: Regenerate. * include/std/memory: Add __glibcxx_want_is_sufficiently_aligned. * src/c++23/std.cc.in (is_sufficiently_aligned): Add. * testsuite/20_util/is_sufficiently_aligned/1.cc: New test. * testsuite/20_util/is_sufficiently_aligned/2.cc: New test.The Signed-off-by: trailer is missing.
Checking for the "Signed-off-by: Luc *" is part of my recently created check_submission.sh. I double checked, these commits would have failed that check today. Other things it checks are: clean git repo and gcc-verify.
--- libstdc++-v3/include/bits/align.h | 16 ++++++++++ libstdc++-v3/include/bits/version.def | 8 +++++ libstdc++-v3/include/bits/version.h | 10 ++++++ libstdc++-v3/include/std/memory | 1 + libstdc++-v3/src/c++23/std.cc.in | 1 + .../20_util/is_sufficiently_aligned/1.cc | 31 +++++++++++++++++++ .../20_util/is_sufficiently_aligned/2.cc | 7 +++++ 7 files changed, 74 insertions(+) create mode 100644 libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/1.cc create mode 100644 libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/2.cc diff --git a/libstdc++-v3/include/bits/align.h b/libstdc++-v3/include/bits/align.h index 2b40c37e033..fbbe9cb1f9c 100644 --- a/libstdc++-v3/include/bits/align.h +++ b/libstdc++-v3/include/bits/align.h @@ -102,6 +102,22 @@ align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept } #endif // __glibcxx_assume_aligned +#ifdef __glibcxx_is_sufficiently_aligned // C++ >= 26 + /** @brief Is @a __ptr aligned to an _Align byte boundary? + * + * @tparam _Align An alignment value + * @tparam _Tp An object type + * + * C++26 20.2.5 [ptr.align] + * + * @ingroup memory + */ + template<size_t _Align, class _Tp> + bool + is_sufficiently_aligned(_Tp* __ptr) + { return reinterpret_cast<__UINTPTR_TYPE__>(__ptr) % _Align == 0; } +#endif // __glibcxx_is_sufficiently_aligned + _GLIBCXX_END_NAMESPACE_VERSION } // namespace diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def index f4ba501c403..a2695e67716 100644 --- a/libstdc++-v3/include/bits/version.def +++ b/libstdc++-v3/include/bits/version.def @@ -732,6 +732,14 @@ ftms = { }; }; +ftms = { + name = is_sufficiently_aligned; + values = { + v = 202411; + cxxmin = 26; + }; +}; + ftms = { name = atomic_flag_test; values = { diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h index dc8ac07be16..1b17a965239 100644 --- a/libstdc++-v3/include/bits/version.h +++ b/libstdc++-v3/include/bits/version.h @@ -815,6 +815,16 @@ #endif /* !defined(__cpp_lib_assume_aligned) && defined(__glibcxx_want_assume_aligned) */ #undef __glibcxx_want_assume_aligned +#if !defined(__cpp_lib_is_sufficiently_aligned) +# if (__cplusplus > 202302L) +# define __glibcxx_is_sufficiently_aligned 202411L +# if defined(__glibcxx_want_all) || defined(__glibcxx_want_is_sufficiently_aligned) +# define __cpp_lib_is_sufficiently_aligned 202411L +# endif +# endif +#endif /* !defined(__cpp_lib_is_sufficiently_aligned) && defined(__glibcxx_want_is_sufficiently_aligned) */ +#undef __glibcxx_want_is_sufficiently_aligned + #if !defined(__cpp_lib_atomic_flag_test) # if (__cplusplus >= 202002L) # define __glibcxx_atomic_flag_test 201907L diff --git a/libstdc++-v3/include/std/memory b/libstdc++-v3/include/std/memory index 1da03b3ea6a..ff342ff35f3 100644 --- a/libstdc++-v3/include/std/memory +++ b/libstdc++-v3/include/std/memory @@ -110,6 +110,7 @@ #define __glibcxx_want_constexpr_memory #define __glibcxx_want_enable_shared_from_this #define __glibcxx_want_indirect +#define __glibcxx_want_is_sufficiently_aligned #define __glibcxx_want_make_unique #define __glibcxx_want_out_ptr #define __glibcxx_want_parallel_algorithm diff --git a/libstdc++-v3/src/c++23/std.cc.in b/libstdc++-v3/src/c++23/std.cc.in index e692caaa5f9..6f4214ed3a7 100644 --- a/libstdc++-v3/src/c++23/std.cc.in +++ b/libstdc++-v3/src/c++23/std.cc.in @@ -1864,6 +1864,7 @@ export namespace std using std::allocator_arg_t; using std::allocator_traits; using std::assume_aligned; + using std::is_sufficiently_aligned; using std::make_obj_using_allocator; using std::pointer_traits; using std::to_address; diff --git a/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/1.cc b/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/1.cc new file mode 100644 index 00000000000..4c2738b57db --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/1.cc @@ -0,0 +1,31 @@ +// { dg-do run { target c++26 } } + +#include <memory> +#include <array> +#include <testsuite_hooks.h> + +void +test01() +{ + constexpr size_t N = 4; + constexpr size_t M = 2*N + 1; + alignas(N) std::array<char, M> buffer{}; + + auto* ptr = buffer.data(); + VERIFY(std::is_sufficiently_aligned<1>(ptr+0)); + VERIFY(std::is_sufficiently_aligned<1>(ptr+1)); + + VERIFY(std::is_sufficiently_aligned<2>(ptr+0)); + VERIFY(!std::is_sufficiently_aligned<2>(ptr+1)); + VERIFY(std::is_sufficiently_aligned<2>(ptr+2)); + + for (size_t i = 0; i < M; ++i) + VERIFY(std::is_sufficiently_aligned<N>(ptr + i) == (i % N == 0)); +} + +int +main() +{ + test01(); + return 0; +} diff --git a/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/2.cc b/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/2.cc new file mode 100644 index 00000000000..8e0f4c07661 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/is_sufficiently_aligned/2.cc @@ -0,0 +1,7 @@ +// { dg-do compile { target c++26 } } + +#include <memory> + +#ifndef __cpp_lib_is_sufficiently_aligned +#error "Missing FTM" +#endif -- 2.49.0
