llvm-project

cef4b98d - [lldb] In symtab serialization, make Section-relative addrs file-offset (#234809)

[lldb] In symtab serialization, make Section-relative addrs file-offset (#234809) On Darwin systems, a dynamic library is usually virtual address 0 based when it is linked, destined to be slid to a random virtual address at runtime via ASLR. Darwin systems link all system libraries into a single Shared Cache collection, and in the process of being added to the shared cache, the virtual address (file address) of the binary is changed to be non-zero -- to be a part of the shared cache which has a file address (and also slides at boot-time). The binaries -- before Shared Cache creation, and after -- both have the same filepath and UUID, but the file addresses in them are different. When lldb creates a DataFileCache symtab serialization of the symbol table based on a 0-offset linked binary, and then reuses that symtab for a Shared Cache non-0-offset file address binary (same filepath, same UUID), when we try to find the correct Section for a Symbol having a Section+offset, it fails because none of the Sections have 0-based file addresses. To address this, when serializing Symbols with section-relative addresses, serialize them as section-id + section-offset. When deserializing, find the same section-id and add the offset to its file address. This change required bumping the DataFileCache symtab version. rdar://190169369 Assisted-By: Claude