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42f811eb1e
The DWARFDie is a lightweight utility wrapper that stores a pointer to a compile unit and a debug info entry. Currently, its iterator (used for walking over its children) stores a DWARFDie and returns a const reference when dereferencing it. When the iterator is modified (by incrementing or decrementing it), this reference becomes invalid. This was happening when calling reverse on it, because the std::reverse_iterator is keeping a temporary copy of the iterator (see https://en.cppreference.com/w/cpp/iterator/reverse_iterator for a good illustration). The relevant code in libcxx: reference operator*() const {_Iter __tmp = current; return *--__tmp;} When dereferencing the reverse iterator, we decrement and return a reference to a DWARFDie stored in the stack frame of this function, resulting in UB at runtime. This patch specifies the std::reverse_iterator for DWARFDie to do the right thing. Differential revision: https://reviews.llvm.org/D49679 llvm-svn: 338506