97b2903455
Currently, both [TypeIdMap](67a1fdb014/llvm/include/llvm/IR/ModuleSummaryIndex.h (L1356)) and [TypeIdCompatibleVtableMap](67a1fdb014/llvm/include/llvm/IR/ModuleSummaryIndex.h (L1363)) keep type-id as `std::string` in the combined index for LTO indexing analysis. With this change, index uses a unique-string-saver to own the string copies and two maps above can use string references to save some memory. This shows a 3% memory reduction (from 8.2GiB to 7.9GiB) in an internal binary with high indexing memory usage.