https://github.com/c-rhodes updated https://github.com/llvm/llvm-project/pull/177383
>From 53d474b4fa47fc7a5809401fe2a3d5e6f1d81e81 Mon Sep 17 00:00:00 2001 From: Jan Svoboda <[email protected]> Date: Thu, 22 Jan 2026 07:15:26 -0800 Subject: [PATCH] [clang][modules] Read PCM validation timestamp earlier (#177062) When building a module, the PCM file is always written first and then the validation timestamp gets created. Clang needs to first read the validation timestamp and only then read the PCM file. Otherwise, it could read an out-of-date PCM file and then read the validation timestamp for its new up-to-date version. This would erroneously skip validation with `-fmodules-validate-once-per-build-session`. I'm not concerned about multiple Clang instances seeing different filesystem contents from each other within a single build session, since that would break the assumption `-fmodules-validate-once-per-build-session` relies on. (cherry picked from commit ada79f4c2691ab6546d379a144377162fd4f5191) --- clang/lib/Serialization/ModuleManager.cpp | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp index 236fe20fdad7c..dad6840947ece 100644 --- a/clang/lib/Serialization/ModuleManager.cpp +++ b/clang/lib/Serialization/ModuleManager.cpp @@ -105,6 +105,10 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type, std::string &ErrorStr) { Module = nullptr; + uint64_t InputFilesValidationTimestamp = 0; + if (Type == MK_ImplicitModule) + InputFilesValidationTimestamp = ModCache.getModuleTimestamp(FileName); + // Look for the file entry. This only fails if the expected size or // modification time differ. OptionalFileEntryRef Entry; @@ -172,11 +176,7 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type, NewModule->Index = Chain.size(); NewModule->FileName = FileName.str(); NewModule->ImportLoc = ImportLoc; - NewModule->InputFilesValidationTimestamp = 0; - - if (NewModule->Kind == MK_ImplicitModule) - NewModule->InputFilesValidationTimestamp = - ModCache.getModuleTimestamp(NewModule->FileName); + NewModule->InputFilesValidationTimestamp = InputFilesValidationTimestamp; // Load the contents of the module if (std::unique_ptr<llvm::MemoryBuffer> Buffer = lookupBuffer(FileName)) { _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
