[libcxx-commits] [libcxx] [libc++][math] Fix undue overflowing of `std::hypot(x, y, z)` (PR #100820)
via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Jul 27 09:58:35 PDT 2024
https://github.com/PaulXiCao updated https://github.com/llvm/llvm-project/pull/100820
>From 79c63cb9ee08411bb04dc3c905d76f75216e2740 Mon Sep 17 00:00:00 2001
From: Paul <paulxicao7 at gmail.com>
Date: Fri, 26 Jul 2024 23:02:43 +0200
Subject: [PATCH 1/4] Reapply "[libc++][math] Fix undue overflowing of
`std::hypot(x,y,z)` (#93350)"
This reverts commit 1031335f2ee1879737576fde3a3425ce0046e773.
---
libcxx/include/__math/hypot.h | 89 ++++++++++++++++++
libcxx/include/cmath | 25 +----
.../test/libcxx/transitive_includes/cxx17.csv | 3 +
.../test/libcxx/transitive_includes/cxx20.csv | 3 +
.../test/libcxx/transitive_includes/cxx23.csv | 3 +
.../test/libcxx/transitive_includes/cxx26.csv | 3 +
.../test/std/numerics/c.math/cmath.pass.cpp | 91 +++++++++++++++----
libcxx/test/support/fp_compare.h | 45 ++++-----
8 files changed, 197 insertions(+), 65 deletions(-)
diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h
index 1bf193a9ab7ee..61fd260c59409 100644
--- a/libcxx/include/__math/hypot.h
+++ b/libcxx/include/__math/hypot.h
@@ -15,10 +15,21 @@
#include <__type_traits/is_same.h>
#include <__type_traits/promote.h>
+#if _LIBCPP_STD_VER >= 17
+# include <__algorithm/max.h>
+# include <__math/abs.h>
+# include <__math/roots.h>
+# include <__utility/pair.h>
+# include <limits>
+#endif
+
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
_LIBCPP_BEGIN_NAMESPACE_STD
namespace __math {
@@ -41,8 +52,86 @@ inline _LIBCPP_HIDE_FROM_ABI typename __promote<_A1, _A2>::type hypot(_A1 __x, _
return __math::hypot((__result_type)__x, (__result_type)__y);
}
+#if _LIBCPP_STD_VER >= 17
+// Factors needed to determine if over-/underflow might happen for `std::hypot(x,y,z)`.
+// returns [overflow_threshold, overflow_scale]
+template <class _Real>
+_LIBCPP_HIDE_FROM_ABI std::pair<_Real, _Real> __hypot_factors() {
+ static_assert(std::numeric_limits<_Real>::is_iec559);
+
+ if constexpr (std::is_same_v<_Real, float>) {
+ static_assert(-125 == std::numeric_limits<_Real>::min_exponent);
+ static_assert(+128 == std::numeric_limits<_Real>::max_exponent);
+ return {0x1.0p+62f, 0x1.0p-70f};
+ } else if constexpr (std::is_same_v<_Real, double>) {
+ static_assert(-1021 == std::numeric_limits<_Real>::min_exponent);
+ static_assert(+1024 == std::numeric_limits<_Real>::max_exponent);
+ return {0x1.0p+510, 0x1.0p-600};
+ } else { // long double
+ static_assert(std::is_same_v<_Real, long double>);
+
+ // preprocessor guard necessary, otherwise literals (e.g. `0x1.0p+8'190l`) throw warnings even when shielded by `if
+ // constexpr`
+# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__
+ static_assert(sizeof(_Real) == sizeof(double));
+ return static_cast<std::pair<_Real, _Real>>(__math::__hypot_factors<double>());
+# else
+ static_assert(sizeof(_Real) > sizeof(double));
+ static_assert(-16381 == std::numeric_limits<_Real>::min_exponent);
+ static_assert(+16384 == std::numeric_limits<_Real>::max_exponent);
+ return {0x1.0p+8190l, 0x1.0p-9000l};
+# endif
+ }
+}
+
+// Computes the three-dimensional hypotenuse: `std::hypot(x,y,z)`.
+// The naive implementation might over-/underflow which is why this implementation is more involved:
+// If the square of an argument might run into issues, we scale the arguments appropriately.
+// See https://github.com/llvm/llvm-project/issues/92782 for a detailed discussion and summary.
+template <class _Real>
+_LIBCPP_HIDE_FROM_ABI _Real __hypot(_Real __x, _Real __y, _Real __z) {
+ const _Real __max_abs = std::max(__math::fabs(__x), std::max(__math::fabs(__y), __math::fabs(__z)));
+ const auto [__overflow_threshold, __overflow_scale] = __math::__hypot_factors<_Real>();
+ _Real __scale;
+ if (__max_abs > __overflow_threshold) { // x*x + y*y + z*z might overflow
+ __scale = __overflow_scale;
+ __x *= __scale;
+ __y *= __scale;
+ __z *= __scale;
+ } else if (__max_abs < 1 / __overflow_threshold) { // x*x + y*y + z*z might underflow
+ __scale = 1 / __overflow_scale;
+ __x *= __scale;
+ __y *= __scale;
+ __z *= __scale;
+ } else
+ __scale = 1;
+ return __math::sqrt(__x * __x + __y * __y + __z * __z) / __scale;
+}
+
+inline _LIBCPP_HIDE_FROM_ABI float hypot(float __x, float __y, float __z) { return __math::__hypot(__x, __y, __z); }
+
+inline _LIBCPP_HIDE_FROM_ABI double hypot(double __x, double __y, double __z) { return __math::__hypot(__x, __y, __z); }
+
+inline _LIBCPP_HIDE_FROM_ABI long double hypot(long double __x, long double __y, long double __z) {
+ return __math::__hypot(__x, __y, __z);
+}
+
+template <class _A1,
+ class _A2,
+ class _A3,
+ std::enable_if_t< is_arithmetic_v<_A1> && is_arithmetic_v<_A2> && is_arithmetic_v<_A3>, int> = 0 >
+_LIBCPP_HIDE_FROM_ABI typename __promote<_A1, _A2, _A3>::type hypot(_A1 __x, _A2 __y, _A3 __z) _NOEXCEPT {
+ using __result_type = typename __promote<_A1, _A2, _A3>::type;
+ static_assert(!(
+ std::is_same_v<_A1, __result_type> && std::is_same_v<_A2, __result_type> && std::is_same_v<_A3, __result_type>));
+ return __math::__hypot(
+ static_cast<__result_type>(__x), static_cast<__result_type>(__y), static_cast<__result_type>(__z));
+}
+#endif
+
} // namespace __math
_LIBCPP_END_NAMESPACE_STD
+_LIBCPP_POP_MACROS
#endif // _LIBCPP___MATH_HYPOT_H
diff --git a/libcxx/include/cmath b/libcxx/include/cmath
index 3c22604a683c3..6480c4678ce33 100644
--- a/libcxx/include/cmath
+++ b/libcxx/include/cmath
@@ -313,6 +313,7 @@ constexpr long double lerp(long double a, long double b, long double t) noexcept
*/
#include <__config>
+#include <__math/hypot.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_arithmetic.h>
#include <__type_traits/is_constant_evaluated.h>
@@ -553,30 +554,6 @@ using ::scalbnl _LIBCPP_USING_IF_EXISTS;
using ::tgammal _LIBCPP_USING_IF_EXISTS;
using ::truncl _LIBCPP_USING_IF_EXISTS;
-#if _LIBCPP_STD_VER >= 17
-inline _LIBCPP_HIDE_FROM_ABI float hypot(float __x, float __y, float __z) {
- return sqrt(__x * __x + __y * __y + __z * __z);
-}
-inline _LIBCPP_HIDE_FROM_ABI double hypot(double __x, double __y, double __z) {
- return sqrt(__x * __x + __y * __y + __z * __z);
-}
-inline _LIBCPP_HIDE_FROM_ABI long double hypot(long double __x, long double __y, long double __z) {
- return sqrt(__x * __x + __y * __y + __z * __z);
-}
-
-template <class _A1, class _A2, class _A3>
-inline _LIBCPP_HIDE_FROM_ABI
-typename enable_if_t< is_arithmetic<_A1>::value && is_arithmetic<_A2>::value && is_arithmetic<_A3>::value,
- __promote<_A1, _A2, _A3> >::type
-hypot(_A1 __lcpp_x, _A2 __lcpp_y, _A3 __lcpp_z) _NOEXCEPT {
- typedef typename __promote<_A1, _A2, _A3>::type __result_type;
- static_assert(
- !(is_same<_A1, __result_type>::value && is_same<_A2, __result_type>::value && is_same<_A3, __result_type>::value),
- "");
- return std::hypot((__result_type)__lcpp_x, (__result_type)__lcpp_y, (__result_type)__lcpp_z);
-}
-#endif
-
template <class _A1, __enable_if_t<is_floating_point<_A1>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool __constexpr_isnan(_A1 __lcpp_x) _NOEXCEPT {
#if __has_builtin(__builtin_isnan)
diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv
index 2c028462144ee..8099d2b79c4be 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx17.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv
@@ -130,6 +130,9 @@ chrono type_traits
chrono vector
chrono version
cinttypes cstdint
+cmath cstddef
+cmath cstdint
+cmath initializer_list
cmath limits
cmath type_traits
cmath version
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv
index 982c2013e3417..384e51b101f31 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx20.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv
@@ -135,6 +135,9 @@ chrono type_traits
chrono vector
chrono version
cinttypes cstdint
+cmath cstddef
+cmath cstdint
+cmath initializer_list
cmath limits
cmath type_traits
cmath version
diff --git a/libcxx/test/libcxx/transitive_includes/cxx23.csv b/libcxx/test/libcxx/transitive_includes/cxx23.csv
index 8ffb71d8b566b..46b833d143f39 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx23.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx23.csv
@@ -83,6 +83,9 @@ chrono string_view
chrono vector
chrono version
cinttypes cstdint
+cmath cstddef
+cmath cstdint
+cmath initializer_list
cmath limits
cmath version
codecvt cctype
diff --git a/libcxx/test/libcxx/transitive_includes/cxx26.csv b/libcxx/test/libcxx/transitive_includes/cxx26.csv
index 8ffb71d8b566b..46b833d143f39 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx26.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx26.csv
@@ -83,6 +83,9 @@ chrono string_view
chrono vector
chrono version
cinttypes cstdint
+cmath cstddef
+cmath cstdint
+cmath initializer_list
cmath limits
cmath version
codecvt cctype
diff --git a/libcxx/test/std/numerics/c.math/cmath.pass.cpp b/libcxx/test/std/numerics/c.math/cmath.pass.cpp
index f53d8f259f47e..6028aa5a21103 100644
--- a/libcxx/test/std/numerics/c.math/cmath.pass.cpp
+++ b/libcxx/test/std/numerics/c.math/cmath.pass.cpp
@@ -12,14 +12,17 @@
// <cmath>
+#include <array>
#include <cmath>
#include <limits>
#include <type_traits>
#include <cassert>
+#include "fp_compare.h"
#include "test_macros.h"
#include "hexfloat.h"
#include "truncate_fp.h"
+#include "type_algorithms.h"
// convertible to int/float/double/etc
template <class T, int N=0>
@@ -1113,6 +1116,56 @@ void test_fmin()
assert(std::fmin(1,0) == 0);
}
+#if TEST_STD_VER >= 17
+struct TestHypot3 {
+ template <class Real>
+ void operator()() const {
+ const auto check = [](Real elem, Real abs_tol) {
+ assert(std::isfinite(std::hypot(elem, Real(0), Real(0))));
+ assert(fptest_close(std::hypot(elem, Real(0), Real(0)), elem, abs_tol));
+ assert(std::isfinite(std::hypot(elem, elem, Real(0))));
+ assert(fptest_close(std::hypot(elem, elem, Real(0)), std::sqrt(Real(2)) * elem, abs_tol));
+ assert(std::isfinite(std::hypot(elem, elem, elem)));
+ assert(fptest_close(std::hypot(elem, elem, elem), std::sqrt(Real(3)) * elem, abs_tol));
+ };
+
+ { // check for overflow
+ const auto [elem, abs_tol] = []() -> std::array<Real, 2> {
+ if constexpr (std::is_same_v<Real, float>)
+ return {1e20f, 1e16f};
+ else if constexpr (std::is_same_v<Real, double>)
+ return {1e300, 1e287};
+ else { // long double
+# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__
+ return {1e300l, 1e287l}; // 64-bit
+# else
+ return {1e4000l, 1e3985l}; // 80- or 128-bit
+# endif
+ }
+ }();
+ check(elem, abs_tol);
+ }
+
+ { // check for underflow
+ const auto [elem, abs_tol] = []() -> std::array<Real, 2> {
+ if constexpr (std::is_same_v<Real, float>)
+ return {1e-20f, 1e-24f};
+ else if constexpr (std::is_same_v<Real, double>)
+ return {1e-287, 1e-300};
+ else { // long double
+# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__
+ return {1e-287l, 1e-300l}; // 64-bit
+# else
+ return {1e-3985l, 1e-4000l}; // 80- or 128-bit
+# endif
+ }
+ }();
+ check(elem, abs_tol);
+ }
+ }
+};
+#endif
+
void test_hypot()
{
static_assert((std::is_same<decltype(std::hypot((float)0, (float)0)), float>::value), "");
@@ -1135,25 +1188,31 @@ void test_hypot()
static_assert((std::is_same<decltype(hypot(Ambiguous(), Ambiguous())), Ambiguous>::value), "");
assert(std::hypot(3,4) == 5);
-#if TEST_STD_VER > 14
- static_assert((std::is_same<decltype(std::hypot((float)0, (float)0, (float)0)), float>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (bool)0, (float)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (unsigned short)0, (double)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (int)0, (long double)0)), long double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (double)0, (long)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (long double)0, (unsigned long)0)), long double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (int)0, (long long)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (int)0, (unsigned long long)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (double)0, (double)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (long double)0, (long double)0)), long double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (float)0, (double)0)), double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (float)0, (long double)0)), long double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((float)0, (double)0, (long double)0)), long double>::value), "");
- static_assert((std::is_same<decltype(std::hypot((int)0, (int)0, (int)0)), double>::value), "");
- static_assert((std::is_same<decltype(hypot(Ambiguous(), Ambiguous(), Ambiguous())), Ambiguous>::value), "");
+#if TEST_STD_VER >= 17
+ // clang-format off
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (float)0, (float)0)), float>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (bool)0, (float)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (unsigned short)0, (double)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (int)0, (long double)0)), long double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (double)0, (long)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (long double)0, (unsigned long)0)), long double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (int)0, (long long)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (int)0, (unsigned long long)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (double)0, (double)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (long double)0, (long double)0)), long double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (float)0, (double)0)), double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (float)0, (long double)0)), long double>));
+ static_assert((std::is_same_v<decltype(std::hypot((float)0, (double)0, (long double)0)), long double>));
+ static_assert((std::is_same_v<decltype(std::hypot((int)0, (int)0, (int)0)), double>));
+ static_assert((std::is_same_v<decltype(hypot(Ambiguous(), Ambiguous(), Ambiguous())), Ambiguous>));
+ // clang-format on
assert(std::hypot(2,3,6) == 7);
assert(std::hypot(1,4,8) == 9);
+
+ // Check for undue over-/underflows of intermediate results.
+ // See discussion at https://github.com/llvm/llvm-project/issues/92782.
+ types::for_each(types::floating_point_types(), TestHypot3());
#endif
}
diff --git a/libcxx/test/support/fp_compare.h b/libcxx/test/support/fp_compare.h
index 1d1933b0bcd81..3088a211dadc3 100644
--- a/libcxx/test/support/fp_compare.h
+++ b/libcxx/test/support/fp_compare.h
@@ -9,39 +9,34 @@
#ifndef SUPPORT_FP_COMPARE_H
#define SUPPORT_FP_COMPARE_H
-#include <cmath> // for std::abs
-#include <algorithm> // for std::max
+#include <cmath> // for std::abs
+#include <algorithm> // for std::max
#include <cassert>
+#include <__config>
// See https://www.boost.org/doc/libs/1_70_0/libs/test/doc/html/boost_test/testing_tools/extended_comparison/floating_point/floating_points_comparison_theory.html
-template<typename T>
-bool fptest_close(T val, T expected, T eps)
-{
- constexpr T zero = T(0);
- assert(eps >= zero);
+template <typename T>
+bool fptest_close(T val, T expected, T eps) {
+ _LIBCPP_CONSTEXPR T zero = T(0);
+ assert(eps >= zero);
- // Handle the zero cases
- if (eps == zero) return val == expected;
- if (val == zero) return std::abs(expected) <= eps;
- if (expected == zero) return std::abs(val) <= eps;
+ // Handle the zero cases
+ if (eps == zero)
+ return val == expected;
+ if (val == zero)
+ return std::abs(expected) <= eps;
+ if (expected == zero)
+ return std::abs(val) <= eps;
- return std::abs(val - expected) < eps
- && std::abs(val - expected)/std::abs(val) < eps;
+ return std::abs(val - expected) < eps && std::abs(val - expected) / std::abs(val) < eps;
}
-template<typename T>
-bool fptest_close_pct(T val, T expected, T percent)
-{
- constexpr T zero = T(0);
- assert(percent >= zero);
-
- // Handle the zero cases
- if (percent == zero) return val == expected;
- T eps = (percent / T(100)) * std::max(std::abs(val), std::abs(expected));
-
- return fptest_close(val, expected, eps);
+template <typename T>
+bool fptest_close_pct(T val, T expected, T percent) {
+ assert(percent >= T(0));
+ T eps = (percent / T(100)) * std::max(std::abs(val), std::abs(expected));
+ return fptest_close(val, expected, eps);
}
-
#endif // SUPPORT_FP_COMPARE_H
>From e9b00a430c29acc67b49050834c09ecdb61d25bb Mon Sep 17 00:00:00 2001
From: Paul <paulxicao7 at gmail.com>
Date: Fri, 26 Jul 2024 23:41:12 +0200
Subject: [PATCH 2/4] generalize computation of hypot_factors
---
libcxx/include/__math/hypot.h | 39 +++++++----------------------------
1 file changed, 7 insertions(+), 32 deletions(-)
diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h
index 61fd260c59409..6ba48c5bd044b 100644
--- a/libcxx/include/__math/hypot.h
+++ b/libcxx/include/__math/hypot.h
@@ -18,6 +18,7 @@
#if _LIBCPP_STD_VER >= 17
# include <__algorithm/max.h>
# include <__math/abs.h>
+# include <__math/exponential_functions.h>
# include <__math/roots.h>
# include <__utility/pair.h>
# include <limits>
@@ -53,45 +54,19 @@ inline _LIBCPP_HIDE_FROM_ABI typename __promote<_A1, _A2>::type hypot(_A1 __x, _
}
#if _LIBCPP_STD_VER >= 17
-// Factors needed to determine if over-/underflow might happen for `std::hypot(x,y,z)`.
-// returns [overflow_threshold, overflow_scale]
-template <class _Real>
-_LIBCPP_HIDE_FROM_ABI std::pair<_Real, _Real> __hypot_factors() {
- static_assert(std::numeric_limits<_Real>::is_iec559);
-
- if constexpr (std::is_same_v<_Real, float>) {
- static_assert(-125 == std::numeric_limits<_Real>::min_exponent);
- static_assert(+128 == std::numeric_limits<_Real>::max_exponent);
- return {0x1.0p+62f, 0x1.0p-70f};
- } else if constexpr (std::is_same_v<_Real, double>) {
- static_assert(-1021 == std::numeric_limits<_Real>::min_exponent);
- static_assert(+1024 == std::numeric_limits<_Real>::max_exponent);
- return {0x1.0p+510, 0x1.0p-600};
- } else { // long double
- static_assert(std::is_same_v<_Real, long double>);
-
- // preprocessor guard necessary, otherwise literals (e.g. `0x1.0p+8'190l`) throw warnings even when shielded by `if
- // constexpr`
-# if __DBL_MAX_EXP__ == __LDBL_MAX_EXP__
- static_assert(sizeof(_Real) == sizeof(double));
- return static_cast<std::pair<_Real, _Real>>(__math::__hypot_factors<double>());
-# else
- static_assert(sizeof(_Real) > sizeof(double));
- static_assert(-16381 == std::numeric_limits<_Real>::min_exponent);
- static_assert(+16384 == std::numeric_limits<_Real>::max_exponent);
- return {0x1.0p+8190l, 0x1.0p-9000l};
-# endif
- }
-}
-
// Computes the three-dimensional hypotenuse: `std::hypot(x,y,z)`.
// The naive implementation might over-/underflow which is why this implementation is more involved:
// If the square of an argument might run into issues, we scale the arguments appropriately.
// See https://github.com/llvm/llvm-project/issues/92782 for a detailed discussion and summary.
template <class _Real>
_LIBCPP_HIDE_FROM_ABI _Real __hypot(_Real __x, _Real __y, _Real __z) {
+ // Factors needed to determine if over-/underflow might happen
+ constexpr int __exp = std::numeric_limits<_Real>::max_exponent / 2;
+ const _Real __overflow_threshold = __math::ldexp(_Real(1), __exp);
+ const _Real __overflow_scale = __math::ldexp(_Real(1), -(__exp + 20));
+
+ // Scale arguments depending on their size
const _Real __max_abs = std::max(__math::fabs(__x), std::max(__math::fabs(__y), __math::fabs(__z)));
- const auto [__overflow_threshold, __overflow_scale] = __math::__hypot_factors<_Real>();
_Real __scale;
if (__max_abs > __overflow_threshold) { // x*x + y*y + z*z might overflow
__scale = __overflow_scale;
>From 0ff240d0fd809be6596605b757c441fda77c1868 Mon Sep 17 00:00:00 2001
From: Paul <paulxicao7 at gmail.com>
Date: Sat, 27 Jul 2024 00:01:00 +0200
Subject: [PATCH 3/4] code style changes
---
libcxx/include/__math/hypot.h | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h
index 6ba48c5bd044b..8819e7e9ad5d0 100644
--- a/libcxx/include/__math/hypot.h
+++ b/libcxx/include/__math/hypot.h
@@ -70,16 +70,16 @@ _LIBCPP_HIDE_FROM_ABI _Real __hypot(_Real __x, _Real __y, _Real __z) {
_Real __scale;
if (__max_abs > __overflow_threshold) { // x*x + y*y + z*z might overflow
__scale = __overflow_scale;
- __x *= __scale;
- __y *= __scale;
- __z *= __scale;
} else if (__max_abs < 1 / __overflow_threshold) { // x*x + y*y + z*z might underflow
__scale = 1 / __overflow_scale;
- __x *= __scale;
- __y *= __scale;
- __z *= __scale;
- } else
+ } else {
__scale = 1;
+ }
+ __x *= __scale;
+ __y *= __scale;
+ __z *= __scale;
+
+ // Compute hypot of scaled arguments and undo scaling
return __math::sqrt(__x * __x + __y * __y + __z * __z) / __scale;
}
>From 7b21cd1ff0c688f0ca95b0f47396324212c69ce4 Mon Sep 17 00:00:00 2001
From: Paul <paulxicao7 at gmail.com>
Date: Sat, 27 Jul 2024 18:58:18 +0200
Subject: [PATCH 4/4] include independent of C++ standard version
---
libcxx/include/__math/hypot.h | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/libcxx/include/__math/hypot.h b/libcxx/include/__math/hypot.h
index 8819e7e9ad5d0..b992163711010 100644
--- a/libcxx/include/__math/hypot.h
+++ b/libcxx/include/__math/hypot.h
@@ -9,20 +9,17 @@
#ifndef _LIBCPP___MATH_HYPOT_H
#define _LIBCPP___MATH_HYPOT_H
+#include <__algorithm/max.h>
#include <__config>
+#include <__math/abs.h>
+#include <__math/exponential_functions.h>
+#include <__math/roots.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_arithmetic.h>
#include <__type_traits/is_same.h>
#include <__type_traits/promote.h>
-
-#if _LIBCPP_STD_VER >= 17
-# include <__algorithm/max.h>
-# include <__math/abs.h>
-# include <__math/exponential_functions.h>
-# include <__math/roots.h>
-# include <__utility/pair.h>
-# include <limits>
-#endif
+#include <__utility/pair.h>
+#include <limits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
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