https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121928
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Slightly simpler version of the "fix it by defining OLD_CODE" change, with a
little more context:
--- a/libstdc++-v3/include/ext/atomicity.h
+++ b/libstdc++-v3/include/ext/atomicity.h
@@ -92,24 +92,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline _Atomic_word
__attribute__((__always_inline__))
__exchange_and_add_single(_Atomic_word* __mem, int __val)
{
_Atomic_word __result = *__mem;
+#ifdef OLD_CODE
+ *__mem += __val;
+#else
+ _Atomic_word __result = *__mem;
// Do the addition with an unsigned type so that overflow is well defined.
#if __cplusplus >= 201103L
std::make_unsigned<_Atomic_word>::type __u;
#else
// For most targets make_unsigned_t<_Atomic_word> is unsigned int,
// but 64-bit sparc uses long for _Atomic_word.
// Sign-extending to unsigned long works for both cases.
unsigned long __u;
#endif
__u = __result;
__u += __val;
*__mem = __u;
+#endif
return __result;
}
inline void
__attribute__((__always_inline__))
__atomic_add_single(_Atomic_word* __mem, int __val)
