libstdc++: Micro-optimization in std::arg overload for scalars

Use __builtin_signbit directly instead of std::signbit.

libstdc++-v3/ChangeLog:

	* include/std/complex (arg(T)): Use __builtin_signbit instead of
	std::signbit.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

diff --git a/libstdc++-v3/include/std/complex b/libstdc++-v3/include/std/complex
index 67f37d4ec2b7bc80f75f8e28af2a392432999767..d9d2d8afda89cf0b34c7cbd9720cf3ab136ac813 100644 (file)
--- a/libstdc++-v3/include/std/complex
+++ b/libstdc++-v3/include/std/complex
@@ -2532,8 +2532,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       typedef typename __gnu_cxx::__promote<_Tp>::__type __type;
 #if (_GLIBCXX11_USE_C99_MATH && !_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC)
-      return std::signbit(__x) ? __type(3.1415926535897932384626433832795029L)
-                              : __type();
+      return __builtin_signbit(__type(__x))
+              ? __type(3.1415926535897932384626433832795029L) : __type();
 #else
       return std::arg(std::complex<__type>(__x));
 #endif