llvm-project

1698beb5 - [clang][modules][deps] Optimize in-process timestamping of PCMs (#137363)

[clang][modules][deps] Optimize in-process timestamping of PCMs (#137363) In the past, timestamps used for `-fmodules-validate-once-per-build-session` were found to be a source of contention in the dependency scanner ([D149802](https://reviews.llvm.org/D149802), https://github.com/llvm/llvm-project/pull/112452). This PR is yet another attempt to optimize these. We now make use of the new `ModuleCache` interface to implement the in-process version in terms of atomic `std::time_t` variables rather the mtime attribute on `.timestamp` files.