2d8a9ad4a9
The non-atomic store that sets both reference counts to zero uses a type-punned pointer, which has undefined behaviour. We could use memset to write 8 bytes, but we don't actually need it to be a single store anyway. No other thread can observe the values, that's why it's safe to use non-atomic stores in the first place. So we can just set each count to zero. With -fstore-merging (which is enabled by default at -O2) GCC produces the same code for this as for memset or the type punned store. Clang does that store merging even at -O1. libstdc++-v3/ChangeLog: PR libstdc++/104019 * include/bits/shared_ptr_base.h (_Sp_counted_base<>::_M_release): Set members to zero without type punning. |
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