[libcxx-commits] [libcxx] [libc++][math] Add `constexpr` for `std::signbit()` (PR #105946)
Robin Caloudis via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Aug 30 00:27:48 PDT 2024
https://github.com/robincaloudis updated https://github.com/llvm/llvm-project/pull/105946
>From f54f52c472334eb7e9c555bf429bb9f75325a80b Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Sat, 24 Aug 2024 18:00:25 +0200
Subject: [PATCH 1/9] Test constexpr for signbit()
---
.../c.math/constexpr-cxx23-clang.pass.cpp | 6 +-
.../c.math/constexpr-cxx23-gcc.pass.cpp | 6 +-
.../test/std/numerics/c.math/signbit.pass.cpp | 131 ++++++++++++++++++
libcxx/test/support/type_algorithms.h | 20 ++-
4 files changed, 150 insertions(+), 13 deletions(-)
create mode 100644 libcxx/test/std/numerics/c.math/signbit.pass.cpp
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
index a07260a34516f1..20887b8cf2678b 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
@@ -220,9 +220,9 @@ int main(int, char**) {
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
index 8c481f41a945ed..d8779706bcee22 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-gcc.pass.cpp
@@ -217,9 +217,9 @@ int main(int, char**) {
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
- ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
+ ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
diff --git a/libcxx/test/std/numerics/c.math/signbit.pass.cpp b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
new file mode 100644
index 00000000000000..cdeab92e0836e2
--- /dev/null
+++ b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
@@ -0,0 +1,131 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// bool signbit(floating-point-type x); // constexpr since C++23
+
+// We don't control the implementation on windows
+// UNSUPPORTED: windows
+
+#include <cassert>
+#include <cmath>
+#include <limits>
+
+#include "test_macros.h"
+#include "type_algorithms.h"
+
+struct TestFloat {
+ template <class T>
+ static TEST_CONSTEXPR_CXX23 bool test() {
+ assert(!std::signbit(T(0)));
+ assert(!std::signbit(std::numeric_limits<T>::min()));
+ assert(!std::signbit(std::numeric_limits<T>::denorm_min()));
+ assert(!std::signbit(std::numeric_limits<T>::max()));
+ assert(!std::signbit(std::numeric_limits<T>::infinity()));
+ assert(!std::signbit(std::numeric_limits<T>::quiet_NaN()));
+ assert(!std::signbit(std::numeric_limits<T>::signaling_NaN()));
+ assert(std::signbit(-T(0)));
+ assert(std::signbit(-std::numeric_limits<T>::infinity()));
+ assert(std::signbit(std::numeric_limits<T>::lowest()));
+
+ return true;
+ }
+
+ template <class T>
+ TEST_CONSTEXPR_CXX23 void operator()() {
+ test<T>();
+#if TEST_STD_VER >= 23
+ static_assert(test<T>());
+#endif
+ }
+};
+
+struct TestUnsignedIntAndFixedWidthChar {
+ template <class T>
+ static TEST_CONSTEXPR_CXX23 bool test() {
+ assert(!std::signbit(std::numeric_limits<T>::max()));
+ assert(!std::signbit(T(0)));
+ assert(!std::signbit(std::numeric_limits<T>::lowest()));
+
+ return true;
+ }
+
+ template <class T>
+ TEST_CONSTEXPR_CXX23 void operator()() {
+ test<T>();
+#if TEST_STD_VER >= 23
+ static_assert(test<T>());
+#endif
+ }
+};
+
+struct TestSignedInt {
+ template <class T>
+ static TEST_CONSTEXPR_CXX23 bool test() {
+ assert(!std::signbit(std::numeric_limits<T>::max()));
+ assert(!std::signbit(T(0)));
+ assert(std::signbit(std::numeric_limits<T>::lowest()));
+
+ return true;
+ }
+
+ template <class T>
+ TEST_CONSTEXPR_CXX23 void operator()() {
+ test<T>();
+#if TEST_STD_VER >= 23
+ static_assert(test<T>());
+#endif
+ }
+};
+
+struct TestVariableWidthChar {
+ template <class T>
+ static TEST_CONSTEXPR_CXX23 bool test() {
+ assert(!std::signbit(std::numeric_limits<T>::max()));
+ assert(!std::signbit(T(0)));
+ // Signed or unsigned depending on the architecture and platform.
+ if (std::is_unsigned<T>::value) {
+ assert(!std::signbit(std::numeric_limits<T>::lowest()));
+ } else {
+ assert(std::signbit(std::numeric_limits<T>::lowest()));
+ }
+
+ return true;
+ }
+
+ template <class T>
+ TEST_CONSTEXPR_CXX23 void operator()() {
+ test<T>();
+#if TEST_STD_VER >= 23
+ static_assert(test<T>());
+#endif
+ }
+};
+
+template <typename T>
+struct ConvertibleTo {
+ operator T() const { return T(); }
+};
+
+int main(int, char**) {
+ types::for_each(types::floating_point_types(), TestFloat());
+ types::for_each(types::concatenate_t<types::unsigned_integer_types, types::fixed_width_character_types>(),
+ TestUnsignedIntAndFixedWidthChar());
+ types::for_each(types::signed_integer_types(), TestSignedInt());
+ types::for_each(types::variable_width_character_types(), TestVariableWidthChar());
+
+ // Make sure we can call `std::signbit` with convertible types. This checks
+ // whether overloads for all cv-unqualified floating-point types are working
+ // as expected.
+ {
+ assert(!std::signbit(ConvertibleTo<float>()));
+ assert(!std::signbit(ConvertibleTo<double>()));
+ assert(!std::signbit(ConvertibleTo<long double>()));
+ }
+
+ return 0;
+}
diff --git a/libcxx/test/support/type_algorithms.h b/libcxx/test/support/type_algorithms.h
index da3d0add4d0c45..6b3b9aba11e5ec 100644
--- a/libcxx/test/support/type_algorithms.h
+++ b/libcxx/test/support/type_algorithms.h
@@ -82,22 +82,28 @@ struct partial_instantiation {
// type categories defined in [basic.fundamental] plus extensions (without CV-qualifiers)
-using character_types =
+using variable_width_character_types =
type_list<char
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
,
wchar_t
#endif
+ >;
+
+using fixed_width_character_types = type_list<
#ifndef TEST_HAS_NO_CHAR8_T
- ,
- char8_t
+ char8_t
#endif
#if TEST_STD_VER >= 11
- ,
- char16_t,
- char32_t
+# ifndef TEST_HAS_NO_CHAR8_T
+ ,
+# endif
+ char16_t,
+ char32_t
#endif
- >;
+ >;
+
+using character_types = concatenate_t<variable_width_character_types, fixed_width_character_types>;
using signed_integer_types =
type_list<signed char,
>From a1d92c4ee2c2aac7a11fe7820882b1736f3bbbad Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Sat, 24 Aug 2024 18:00:56 +0200
Subject: [PATCH 2/9] Add constexpr for signbit()
---
libcxx/include/__math/traits.h | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index 0638a6949580eb..9be06b7b8efae9 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -28,17 +28,29 @@ namespace __math {
// signbit
template <class _A1, __enable_if_t<is_floating_point<_A1>::value, int> = 0>
-_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
+ return __builtin_signbit(__x);
+}
+
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
+ return __builtin_signbit(__x);
+}
+
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
+ return __builtin_signbit(__x);
+}
+
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
return __builtin_signbit(__x);
}
template <class _A1, __enable_if_t<is_integral<_A1>::value && is_signed<_A1>::value, int> = 0>
-_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
return __x < 0;
}
template <class _A1, __enable_if_t<is_integral<_A1>::value && !is_signed<_A1>::value, int> = 0>
-_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI bool signbit(_A1) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1) _NOEXCEPT {
return false;
}
>From a9e2291a0ae7e62e2adc0df9ed535ba0a4d73ca4 Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Sat, 24 Aug 2024 18:01:43 +0200
Subject: [PATCH 3/9] Update cxx23 status
---
libcxx/docs/Status/Cxx23Papers.csv | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/docs/Status/Cxx23Papers.csv b/libcxx/docs/Status/Cxx23Papers.csv
index 2c8a91d8401b53..20bd7b70a0d619 100644
--- a/libcxx/docs/Status/Cxx23Papers.csv
+++ b/libcxx/docs/Status/Cxx23Papers.csv
@@ -39,7 +39,7 @@
"`P2401R0 <https://wg21.link/P2401R0>`__","Add a conditional ``noexcept`` specification to ``std::exchange``","2021-10 (Virtual)","|Complete|","14.0",""
"","","","","",""
"`P0323R12 <https://wg21.link/P0323R12>`__","``std::expected``","2022-02 (Virtual)","|Complete|","16.0",""
-"`P0533R9 <https://wg21.link/P0533R9>`__","``constexpr`` for ``<cmath>`` and ``<cstdlib>``","2022-02 (Virtual)","|In Progress|","","``isfinite``, ``isinf``, ``isnan`` and ``isnormal`` are implemented"
+"`P0533R9 <https://wg21.link/P0533R9>`__","``constexpr`` for ``<cmath>`` and ``<cstdlib>``","2022-02 (Virtual)","|In Progress|","","``isfinite``, ``isinf``, ``isnan``, ``isnormal`` and ``signbit`` are implemented"
"`P0627R6 <https://wg21.link/P0627R6>`__","Function to mark unreachable code","2022-02 (Virtual)","|Complete|","15.0",""
"`P1206R7 <https://wg21.link/P1206R7>`__","``ranges::to``: A function to convert any range to a container","2022-02 (Virtual)","|Complete|","17.0",""
"`P1413R3 <https://wg21.link/P1413R3>`__","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","2022-02 (Virtual)","|Complete|","","``std::aligned_storage_t`` and ``std::aligned_union_t`` are marked deprecated, but clang doesn't issue a diagnostic for deprecated using template declarations."
>From 1369b39a73391af76cea178b44b0203a44cde4be Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Sat, 24 Aug 2024 20:51:54 +0200
Subject: [PATCH 4/9] Use signcopy workaround
If constexpr signbit is not available, we make
use of signcopy(), which has been constexpr for
quite a while in Clang.
---
libcxx/include/__math/traits.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index 9be06b7b8efae9..077f0aea5b7a91 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -29,19 +29,39 @@ namespace __math {
template <class _A1, __enable_if_t<is_floating_point<_A1>::value, int> = 0>
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
+// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
+#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
+ return __builtin_copysign(1.0, __x) == -1.0;
+#else
return __builtin_signbit(__x);
+#endif
}
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
+// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
+#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
+ return __builtin_copysign(1.0, __x) == -1.0;
+#else
return __builtin_signbit(__x);
+#endif
}
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
+// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
+#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
+ return __builtin_copysign(1.0, __x) == -1.0;
+#else
return __builtin_signbit(__x);
+#endif
}
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
+// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
+#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
+ return __builtin_copysign(1.0, __x) == -1.0;
+#else
return __builtin_signbit(__x);
+#endif
}
template <class _A1, __enable_if_t<is_integral<_A1>::value && is_signed<_A1>::value, int> = 0>
>From 23559f0532e13f4736a289859827359f3a5614a3 Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Sun, 25 Aug 2024 00:39:30 +0200
Subject: [PATCH 5/9] Prefer libcxx overload
By using `_LIBCPP_PREFERRED_OVERLOAD` we make
sure that a given overload is a better match
than an otherwise equally good function
declaration.
Why is there an equally good function
declaration in the first place? Underlying the
Windows SDK is the UCRT, the universal C runtime,
which clang-cl makes use of. The UCRT should
provide only C library headers, but does on top
comes with overloads for all cv-unqualified floating
point types (float, double, long double) for
`std::signbit()` in https://github.com/microsoft/win32metadata/blob/e012b29924c53aa941fc010850b68331b0c3ea80/generation/WinSDK/RecompiledIdlHeaders/ucrt/corecrt_math.h#L309-L322.
In a certain way, this can be seen as a deviation
from the C standard. We need to work around it.
---
libcxx/include/__math/traits.h | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index 077f0aea5b7a91..e668c5805cea39 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -37,7 +37,12 @@ _LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI boo
#endif
}
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(float __x) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
+#ifdef _LIBCPP_PREFERRED_OVERLOAD
+_LIBCPP_PREFERRED_OVERLOAD
+#endif
+ bool
+ signbit(float __x) _NOEXCEPT {
// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
return __builtin_copysign(1.0, __x) == -1.0;
@@ -46,7 +51,12 @@ _LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI boo
#endif
}
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(double __x) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
+#ifdef _LIBCPP_PREFERRED_OVERLOAD
+_LIBCPP_PREFERRED_OVERLOAD
+#endif
+ bool
+ signbit(double __x) _NOEXCEPT {
// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
return __builtin_copysign(1.0, __x) == -1.0;
@@ -55,7 +65,12 @@ _LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI boo
#endif
}
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(long double __x) _NOEXCEPT {
+_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
+#ifdef _LIBCPP_PREFERRED_OVERLOAD
+_LIBCPP_PREFERRED_OVERLOAD
+#endif
+ bool
+ signbit(long double __x) _NOEXCEPT {
// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
return __builtin_copysign(1.0, __x) == -1.0;
>From f160b6a5fcecee515cb154aacfdfe22b68dcc6ae Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Thu, 29 Aug 2024 08:55:59 +0200
Subject: [PATCH 6/9] Reduce complexity of tests
---
.../test/std/numerics/c.math/signbit.pass.cpp | 46 +------------------
libcxx/test/support/type_algorithms.h | 20 +++-----
2 files changed, 9 insertions(+), 57 deletions(-)
diff --git a/libcxx/test/std/numerics/c.math/signbit.pass.cpp b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
index cdeab92e0836e2..08e785b1d3c61c 100644
--- a/libcxx/test/std/numerics/c.math/signbit.pass.cpp
+++ b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
@@ -44,50 +44,11 @@ struct TestFloat {
}
};
-struct TestUnsignedIntAndFixedWidthChar {
+struct TestInt {
template <class T>
static TEST_CONSTEXPR_CXX23 bool test() {
assert(!std::signbit(std::numeric_limits<T>::max()));
assert(!std::signbit(T(0)));
- assert(!std::signbit(std::numeric_limits<T>::lowest()));
-
- return true;
- }
-
- template <class T>
- TEST_CONSTEXPR_CXX23 void operator()() {
- test<T>();
-#if TEST_STD_VER >= 23
- static_assert(test<T>());
-#endif
- }
-};
-
-struct TestSignedInt {
- template <class T>
- static TEST_CONSTEXPR_CXX23 bool test() {
- assert(!std::signbit(std::numeric_limits<T>::max()));
- assert(!std::signbit(T(0)));
- assert(std::signbit(std::numeric_limits<T>::lowest()));
-
- return true;
- }
-
- template <class T>
- TEST_CONSTEXPR_CXX23 void operator()() {
- test<T>();
-#if TEST_STD_VER >= 23
- static_assert(test<T>());
-#endif
- }
-};
-
-struct TestVariableWidthChar {
- template <class T>
- static TEST_CONSTEXPR_CXX23 bool test() {
- assert(!std::signbit(std::numeric_limits<T>::max()));
- assert(!std::signbit(T(0)));
- // Signed or unsigned depending on the architecture and platform.
if (std::is_unsigned<T>::value) {
assert(!std::signbit(std::numeric_limits<T>::lowest()));
} else {
@@ -113,10 +74,7 @@ struct ConvertibleTo {
int main(int, char**) {
types::for_each(types::floating_point_types(), TestFloat());
- types::for_each(types::concatenate_t<types::unsigned_integer_types, types::fixed_width_character_types>(),
- TestUnsignedIntAndFixedWidthChar());
- types::for_each(types::signed_integer_types(), TestSignedInt());
- types::for_each(types::variable_width_character_types(), TestVariableWidthChar());
+ types::for_each(types::integral_types(), TestInt());
// Make sure we can call `std::signbit` with convertible types. This checks
// whether overloads for all cv-unqualified floating-point types are working
diff --git a/libcxx/test/support/type_algorithms.h b/libcxx/test/support/type_algorithms.h
index 6b3b9aba11e5ec..da3d0add4d0c45 100644
--- a/libcxx/test/support/type_algorithms.h
+++ b/libcxx/test/support/type_algorithms.h
@@ -82,28 +82,22 @@ struct partial_instantiation {
// type categories defined in [basic.fundamental] plus extensions (without CV-qualifiers)
-using variable_width_character_types =
+using character_types =
type_list<char
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
,
wchar_t
#endif
- >;
-
-using fixed_width_character_types = type_list<
#ifndef TEST_HAS_NO_CHAR8_T
- char8_t
+ ,
+ char8_t
#endif
#if TEST_STD_VER >= 11
-# ifndef TEST_HAS_NO_CHAR8_T
- ,
-# endif
- char16_t,
- char32_t
+ ,
+ char16_t,
+ char32_t
#endif
- >;
-
-using character_types = concatenate_t<variable_width_character_types, fixed_width_character_types>;
+ >;
using signed_integer_types =
type_list<signed char,
>From b5282000413b32d890530d5b0f8ee49e4d2d7b5d Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Thu, 29 Aug 2024 16:42:57 +0200
Subject: [PATCH 7/9] Apply constexpr only when builtin is
---
libcxx/include/__math/traits.h | 13 +++++++------
.../numerics/c.math/constexpr-cxx23-clang.pass.cpp | 7 +++++++
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index e668c5805cea39..ff5b9e09fecb96 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -28,13 +28,14 @@ namespace __math {
// signbit
template <class _A1, __enable_if_t<is_floating_point<_A1>::value, int> = 0>
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
-// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
-#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
- return __builtin_copysign(1.0, __x) == -1.0;
-#else
- return __builtin_signbit(__x);
+_LIBCPP_NODISCARD inline
+// TODO(LLVM 22): Remove `__has_constexpr_builtin` conditional once support for Clang 19 is dropped.
+#if __has_constexpr_builtin(__builtin_signbit)
+ _LIBCPP_CONSTEXPR_SINCE_CXX23
#endif
+ _LIBCPP_HIDE_FROM_ABI bool
+ signbit(_A1 __x) _NOEXCEPT {
+ return __builtin_signbit(__x);
}
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
diff --git a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
index 20887b8cf2678b..3f17f21e8c1087 100644
--- a/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
+++ b/libcxx/test/libcxx/numerics/c.math/constexpr-cxx23-clang.pass.cpp
@@ -220,9 +220,16 @@ int main(int, char**) {
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
+// TODO(LLVM 22): Remove `__has_constexpr_builtin` conditional once support for Clang 19 is dropped.
+#if !__has_constexpr_builtin(__builtin_signbit)
+ ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
+ ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
+ ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
+#else
ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
ASSERT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
+#endif
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
>From fc1973ddc193420f3135e6d42e918750bc096d09 Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Thu, 29 Aug 2024 16:43:41 +0200
Subject: [PATCH 8/9] Remove overloads
We will add the overloads in a seperate
patch.
---
libcxx/include/__math/traits.h | 42 -------------------
.../test/std/numerics/c.math/signbit.pass.cpp | 9 ----
2 files changed, 51 deletions(-)
diff --git a/libcxx/include/__math/traits.h b/libcxx/include/__math/traits.h
index ff5b9e09fecb96..b2e81b997f3721 100644
--- a/libcxx/include/__math/traits.h
+++ b/libcxx/include/__math/traits.h
@@ -38,48 +38,6 @@ _LIBCPP_NODISCARD inline
return __builtin_signbit(__x);
}
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
-#ifdef _LIBCPP_PREFERRED_OVERLOAD
-_LIBCPP_PREFERRED_OVERLOAD
-#endif
- bool
- signbit(float __x) _NOEXCEPT {
-// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
-#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
- return __builtin_copysign(1.0, __x) == -1.0;
-#else
- return __builtin_signbit(__x);
-#endif
-}
-
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
-#ifdef _LIBCPP_PREFERRED_OVERLOAD
-_LIBCPP_PREFERRED_OVERLOAD
-#endif
- bool
- signbit(double __x) _NOEXCEPT {
-// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
-#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
- return __builtin_copysign(1.0, __x) == -1.0;
-#else
- return __builtin_signbit(__x);
-#endif
-}
-
-_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
-#ifdef _LIBCPP_PREFERRED_OVERLOAD
-_LIBCPP_PREFERRED_OVERLOAD
-#endif
- bool
- signbit(long double __x) _NOEXCEPT {
-// TODO(LLVM 22): Remove `__builtin_copysign`-workaround once support for Clang 19 is dropped.
-#if !__has_constexpr_builtin(__builtin_signbit) && _LIBCPP_STD_VER >= 23
- return __builtin_copysign(1.0, __x) == -1.0;
-#else
- return __builtin_signbit(__x);
-#endif
-}
-
template <class _A1, __enable_if_t<is_integral<_A1>::value && is_signed<_A1>::value, int> = 0>
_LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool signbit(_A1 __x) _NOEXCEPT {
return __x < 0;
diff --git a/libcxx/test/std/numerics/c.math/signbit.pass.cpp b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
index 08e785b1d3c61c..3d1231e84e0ec2 100644
--- a/libcxx/test/std/numerics/c.math/signbit.pass.cpp
+++ b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
@@ -76,14 +76,5 @@ int main(int, char**) {
types::for_each(types::floating_point_types(), TestFloat());
types::for_each(types::integral_types(), TestInt());
- // Make sure we can call `std::signbit` with convertible types. This checks
- // whether overloads for all cv-unqualified floating-point types are working
- // as expected.
- {
- assert(!std::signbit(ConvertibleTo<float>()));
- assert(!std::signbit(ConvertibleTo<double>()));
- assert(!std::signbit(ConvertibleTo<long double>()));
- }
-
return 0;
}
>From cbd07774c48f39a177d30e91d7d9538cb5954e79 Mon Sep 17 00:00:00 2001
From: Robin Caloudis <robin.caloudis at gmx.de>
Date: Thu, 29 Aug 2024 23:41:48 +0200
Subject: [PATCH 9/9] Restrict test to tip-of-trunk Clang
---
libcxx/test/std/numerics/c.math/signbit.pass.cpp | 3 +++
1 file changed, 3 insertions(+)
diff --git a/libcxx/test/std/numerics/c.math/signbit.pass.cpp b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
index 3d1231e84e0ec2..b862abc0b06d46 100644
--- a/libcxx/test/std/numerics/c.math/signbit.pass.cpp
+++ b/libcxx/test/std/numerics/c.math/signbit.pass.cpp
@@ -11,6 +11,9 @@
// We don't control the implementation on windows
// UNSUPPORTED: windows
+// These compilers don't support constexpr `__builtin_signbit` yet.
+// UNSUPPORTED: clang-17, clang-18, clang-19, gcc-14, apple-clang-16, apple-clang-17
+
#include <cassert>
#include <cmath>
#include <limits>
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