This reverts commit 0fa20c55b58deb94090985a5c5ffda4d5ceb3cd1. Storing raw symbol names is generally preferred in profile files. Demangling might lose information. Language frontends might use demangling schemes not supported by LLVMDemangle (https://github.com/llvm/llvm-project/issues/45901#issuecomment-2008686663). In addition, calling `demangle` for each function has a significant performance overhead (#102222). I believe that even if we decide to provide a producer-side demangling, it would not be on by default. Pull Request: https://github.com/llvm/llvm-project/pull/102274 (cherry picked from commit 72b73e23b6c36537db730ebea00f92798108a6e5)