CppCon 2019

Both the C++ and C standards currently specify that all pointers to an object become invalid (in the case of C, "indeterminate") at the end of that object's lifetime. In other words, your program's nice well-behaved pointers become vicious zombies. This transformation to zombies permits some additional diagnostics and optimizations, some deployed and some hypothetical, but it is not consistent with long-standing usage, especially for a range of concurrent and sequential algorithms that rely on loads, stores, and equality comparisons of such pointers. In fact, a few long-standing concurrent algorithms rely on assembly-language-style reincarnation of a zombie pointer when a new object is allocated at that same address.

This presentation gives an overview of several of these algorithms and discusses a range of possible ways of rehabilitating zombie pointers.