My r16-3810-g6456da6bab8a2c changes broke bootstrap for targets that use
the mutex-based atomic helpers. This fixes it by casting away the
unnecessary volatile-qualification on the _Atomic_word* before passing
it to __exchange_and_add_single.
libstdc++-v3/ChangeLog:
* config/cpu/generic/atomicity_mutex/atomicity.h
(__exchange_and_add): Use const_cast to remove volatile.
---
Tested powerpc64le-linux, bootstrapped on msp430-elf and
pru-unknown-elf.
Pushed to trunk.
libstdc++-v3/config/cpu/generic/atomicity_mutex/atomicity.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/config/cpu/generic/atomicity_mutex/atomicity.h
b/libstdc++-v3/config/cpu/generic/atomicity_mutex/atomicity.h
index 7d5772d54840..d088f69fe9a4 100644
--- a/libstdc++-v3/config/cpu/generic/atomicity_mutex/atomicity.h
+++ b/libstdc++-v3/config/cpu/generic/atomicity_mutex/atomicity.h
@@ -44,7 +44,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__exchange_and_add(volatile _Atomic_word* __mem, int __val) throw ()
{
__gnu_cxx::__scoped_lock sentry(get_atomic_mutex());
- return __gnu_cxx::__exchange_and_add_single(__mem, __val);
+ // The volatile qualification is meaningless. All changes to the memory
+ // location happen while this mutex is locked so it's not volatile at all.
+ auto __mem2 = const_cast<_Atomic_word*>(__mem);
+ return __gnu_cxx::__exchange_and_add_single(__mem2, __val);
}
void
--
2.51.0
