[gcc r17-2310] libstdc++: Fix Cylindrical Bessel functions for infinity [PR119143]

https://gcc.gnu.org/g:62bc11d461f6e5a150c6c0593a0cec5851b76b19

commit r17-2310-g62bc11d461f6e5a150c6c0593a0cec5851b76b19
Author: Jonathan Wakely <[email protected]>
Date:   Fri Jun 5 15:51:23 2026 +0100

    libstdc++: Fix Cylindrical Bessel functions for infinity [PR119143]
    
    The result should be zero at infinity.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/119143
            * include/tr1/bessel_function.tcc (__cyl_bessel_jn_asymp):
            Return zero for infinite x.
            * testsuite/special_functions/08_cyl_bessel_j/check_inf.cc: New
            test.
            * testsuite/special_functions/10_cyl_neumann/check_inf.cc: New
            test.
            * testsuite/tr1/5_numerical_facilities/special_functions/11_cyl_neumann/check_inf.cc:
            New test.
            * testsuite/tr1/5_numerical_facilities/special_functions/09_cyl_bessel_j/check_inf.cc:
            New test.
    
    Reviewed-by: Tomasz Kamiński <[email protected]>

Diff:
---
 libstdc++-v3/include/tr1/bessel_function.tcc       |  6 ++++
 .../special_functions/08_cyl_bessel_j/check_inf.cc | 38 ++++++++++++++++++++++
 .../special_functions/10_cyl_neumann/check_inf.cc  | 38 ++++++++++++++++++++++
 .../special_functions/09_cyl_bessel_j/check_inf.cc | 36 ++++++++++++++++++++
 .../special_functions/11_cyl_neumann/check_inf.cc  | 37 +++++++++++++++++++++
 5 files changed, 155 insertions(+)

diff --git a/libstdc++-v3/include/tr1/bessel_function.tcc b/libstdc++-v3/include/tr1/bessel_function.tcc
index 7e06d98ce3c6..bba792bd89d3 100644
--- a/libstdc++-v3/include/tr1/bessel_function.tcc
+++ b/libstdc++-v3/include/tr1/bessel_function.tcc
@@ -362,6 +362,12 @@ namespace tr1
     void
     __cyl_bessel_jn_asymp(_Tp __nu, _Tp __x, _Tp & __Jnu, _Tp & __Nnu)
     {
+      if (__builtin_expect(__builtin_isinf(__x), 0))
+	{
+	  __Jnu = __Nnu = _Tp(0);
+	  return;
+	}
+
       const _Tp __mu = _Tp(4) * __nu * __nu;
       const _Tp __8x = _Tp(8) * __x;
 
diff --git a/libstdc++-v3/testsuite/special_functions/08_cyl_bessel_j/check_inf.cc b/libstdc++-v3/testsuite/special_functions/08_cyl_bessel_j/check_inf.cc
new file mode 100644
index 000000000000..50c1f3098297
--- /dev/null
+++ b/libstdc++-v3/testsuite/special_functions/08_cyl_bessel_j/check_inf.cc
@@ -0,0 +1,38 @@
+// { dg-do run { target c++11 } }
+// { dg-require-c-std "" }
+// { dg-options "-D__STDCPP_WANT_MATH_SPEC_FUNCS__" }
+// { dg-add-options ieee }
+
+// ISO/IEC IS 29124 8.1.8 cyl_bessel_j
+// J_nu(+inf) == 0 for all finite nu >= 0
+
+#include <cmath>
+#include <limits>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  float xinf_f = std::numeric_limits<float>::infinity();
+  double xinf_d = std::numeric_limits<double>::infinity();
+  long double xinf_l = std::numeric_limits<long double>::infinity();
+
+  VERIFY(std::cyl_bessel_j(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_bessel_jf(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_bessel_j(0.0, xinf_d) == 0.0);
+  VERIFY(std::cyl_bessel_j(0.0L, xinf_l) == 0.0L);
+  VERIFY(std::cyl_bessel_jl(0.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::cyl_bessel_j(1.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_bessel_j(1.0, xinf_d) == 0.0);
+  VERIFY(std::cyl_bessel_j(1.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::cyl_bessel_j(2.5, xinf_d) == 0.0);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/special_functions/10_cyl_neumann/check_inf.cc b/libstdc++-v3/testsuite/special_functions/10_cyl_neumann/check_inf.cc
new file mode 100644
index 000000000000..716dc79b1aab
--- /dev/null
+++ b/libstdc++-v3/testsuite/special_functions/10_cyl_neumann/check_inf.cc
@@ -0,0 +1,38 @@
+// { dg-do run { target c++11 } }
+// { dg-require-c-std "" }
+// { dg-options "-D__STDCPP_WANT_MATH_SPEC_FUNCS__" }
+// { dg-add-options ieee }
+
+// ISO/IEC IS 29124 8.1.10 cyl_neumann
+// N_nu(+inf) == 0 for all finite nu >= 0
+
+#include <cmath>
+#include <limits>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  float xinf_f = std::numeric_limits<float>::infinity();
+  double xinf_d = std::numeric_limits<double>::infinity();
+  long double xinf_l = std::numeric_limits<long double>::infinity();
+
+  VERIFY(std::cyl_neumann(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_neumannf(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_neumann(0.0, xinf_d) == 0.0);
+  VERIFY(std::cyl_neumann(0.0L, xinf_l) == 0.0L);
+  VERIFY(std::cyl_neumannl(0.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::cyl_neumann(1.0F, xinf_f) == 0.0F);
+  VERIFY(std::cyl_neumann(1.0, xinf_d) == 0.0);
+  VERIFY(std::cyl_neumann(1.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::cyl_neumann(2.5, xinf_d) == 0.0);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/09_cyl_bessel_j/check_inf.cc b/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/09_cyl_bessel_j/check_inf.cc
new file mode 100644
index 000000000000..d05b7b8c9e3b
--- /dev/null
+++ b/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/09_cyl_bessel_j/check_inf.cc
@@ -0,0 +1,36 @@
+// { dg-require-c-std "" }
+// { dg-add-options ieee }
+
+// TR1 5.2.1.9 cyl_bessel_j
+// J_nu(+inf) == 0 for all finite nu >= 0
+
+#include <tr1/cmath>
+#include <limits>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  float xinf_f = std::numeric_limits<float>::infinity();
+  double xinf_d = std::numeric_limits<double>::infinity();
+  long double xinf_l = std::numeric_limits<long double>::infinity();
+
+  VERIFY(std::tr1::cyl_bessel_j(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_bessel_jf(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_bessel_j(0.0, xinf_d) == 0.0);
+  VERIFY(std::tr1::cyl_bessel_j(0.0L, xinf_l) == 0.0L);
+  VERIFY(std::tr1::cyl_bessel_jl(0.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::tr1::cyl_bessel_j(1.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_bessel_j(1.0, xinf_d) == 0.0);
+  VERIFY(std::tr1::cyl_bessel_j(1.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::tr1::cyl_bessel_j(2.5, xinf_d) == 0.0);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/11_cyl_neumann/check_inf.cc b/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/11_cyl_neumann/check_inf.cc
new file mode 100644
index 000000000000..9294cab64db0
--- /dev/null
+++ b/libstdc++-v3/testsuite/tr1/5_numerical_facilities/special_functions/11_cyl_neumann/check_inf.cc
@@ -0,0 +1,37 @@
+// { dg-require-c-std "" }
+// { dg-add-options ieee }
+
+// TR1 5.2.1.11 cyl_neumann
+// N_nu(+inf) == 0 for all finite nu >= 0
+
+#include <tr1/cmath>
+#include <limits>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  float xinf_f = std::numeric_limits<float>::infinity();
+  double xinf_d = std::numeric_limits<double>::infinity();
+  long double xinf_l = std::numeric_limits<long double>::infinity();
+
+  VERIFY(std::tr1::cyl_neumann(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_neumannf(0.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_neumann(0.0, xinf_d) == 0.0);
+  VERIFY(std::tr1::cyl_neumann(0.0L, xinf_l) == 0.0L);
+  VERIFY(std::tr1::cyl_neumannl(0.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::tr1::cyl_neumann(1.0F, xinf_f) == 0.0F);
+  VERIFY(std::tr1::cyl_neumann(1.0, xinf_d) == 0.0);
+  VERIFY(std::tr1::cyl_neumann(1.0L, xinf_l) == 0.0L);
+
+  VERIFY(std::tr1::cyl_neumann(2.5, xinf_d) == 0.0);
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
+