d067bd7293
The rope extension uses a volatile variable for its reference count. This is not only unnecessary for correctness (volatile provides neither atomicity nor memory visibility, and the variable is only modified while a lock is held) but it now causes deprecated warnings with -Wsystem-headers due to the use of ++ and -- operators. It would be possible to use __gnu_cxx::__exchange_and_add in _M_incr and _M_decr when __atomic_is_lock_free(sizeof(_RC_t), &_M_ref_count) is true, rather than locking a mutex. That would probably be a significant improvement for multi-threaded and single-threaded code (because __exchange_and_add will use non-atomic ops when possible, and even in MT code it should be faster than the mutex lock/unlock pair). However, mixing objects compiled with the old and new code would result in inconsistent synchronization being used for the reference count. libstdc++-v3/ChangeLog: * include/ext/rope (_Refcount_Base::_M_ref_count): Remove volatile qualifier. (_Refcount_Base::_M_decr()): Likewise. |
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| .. | ||
| pb_ds | ||
| algorithm | ||
| aligned_buffer.h | ||
| alloc_traits.h | ||
| atomicity.h | ||
| bitmap_allocator.h | ||
| cast.h | ||
| cmath | ||
| codecvt_specializations.h | ||
| concurrence.h | ||
| debug_allocator.h | ||
| enc_filebuf.h | ||
| extptr_allocator.h | ||
| functional | ||
| iterator | ||
| malloc_allocator.h | ||
| memory | ||
| mt_allocator.h | ||
| new_allocator.h | ||
| numeric | ||
| numeric_traits.h | ||
| pod_char_traits.h | ||
| pointer.h | ||
| pool_allocator.h | ||
| random | ||
| random.tcc | ||
| rb_tree | ||
| rc_string_base.h | ||
| rope | ||
| ropeimpl.h | ||
| slist | ||
| sso_string_base.h | ||
| stdio_filebuf.h | ||
| stdio_sync_filebuf.h | ||
| string_conversions.h | ||
| throw_allocator.h | ||
| type_traits.h | ||
| typelist.h | ||
| vstring_fwd.h | ||
| vstring_util.h | ||
| vstring.h | ||
| vstring.tcc | ||