[clang][modules] Timestamp-less validation API (#138983)

Timestamps are an implementation detail of the cross-process module
cache implementation. This PR hides it from the `ModuleCache` API, which
simplifies the in-process implementation.

4 files changed, 21 insertions, 16 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index d068f5e1..2462b5c 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3103,8 +3103,7 @@ ASTReader::ReadControlBlock(ModuleFile &F,
 
         unsigned N = ValidateSystemInputs ? NumInputs : NumUserInputs;
         if (HSOpts.ModulesValidateOncePerBuildSession &&
-            F.InputFilesValidationTimestamp > HSOpts.BuildSessionTimestamp &&
-            F.Kind == MK_ImplicitModule)
+            F.InputFilesValidated && F.Kind == MK_ImplicitModule)
           N = ForceValidateUserInputs ? NumUserInputs : 0;
 
         for (unsigned I = 0; I < N; ++I) {
@@ -4950,10 +4949,8 @@ ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName, ModuleKind Type,
     // timestamp files are up-to-date in this build session.
     for (unsigned I = 0, N = Loaded.size(); I != N; ++I) {
       ImportedModule &M = Loaded[I];
-      if (M.Mod->Kind == MK_ImplicitModule &&
-          M.Mod->InputFilesValidationTimestamp < HSOpts.BuildSessionTimestamp)
-        getModuleManager().getModuleCache().updateModuleTimestamp(
-            M.Mod->FileName);
+      if (M.Mod->Kind == MK_ImplicitModule && !M.Mod->InputFilesValidated)
+        getModuleManager().getModuleCache().markUpToDate(M.Mod->FileName);
     }
   }
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 1b3d3c2..491149b 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -5391,7 +5391,7 @@ ASTWriter::WriteAST(llvm::PointerUnion<Sema *, Preprocessor *> Subject,
   if (WritingModule && PPRef.getHeaderSearchInfo()
                            .getHeaderSearchOpts()
                            .ModulesValidateOncePerBuildSession)
-    ModCache.updateModuleTimestamp(OutputFile);
+    ModCache.markUpToDate(OutputFile);
 
   if (ShouldCacheASTInMemory) {
     // Construct MemoryBuffer and update buffer manager.
diff --git a/clang/lib/Serialization/ModuleCache.cpp b/clang/lib/Serialization/ModuleCache.cpp
index 4ae49c4..43f8ff8 100644
--- a/clang/lib/Serialization/ModuleCache.cpp
+++ b/clang/lib/Serialization/ModuleCache.cpp
@@ -20,7 +20,12 @@ namespace {
 class CrossProcessModuleCache : public ModuleCache {
   InMemoryModuleCache InMemory;
 
+  std::time_t BuildSessionTimestamp;
+
 public:
+  explicit CrossProcessModuleCache(std::time_t BuildSessionTimestamp)
+      : BuildSessionTimestamp(BuildSessionTimestamp) {}
+
   void prepareForGetLock(StringRef ModuleFilename) override {
     // FIXME: Do this in LockFileManager and only if the directory doesn't
     // exist.
@@ -33,16 +38,17 @@ public:
     return std::make_unique<llvm::LockFileManager>(ModuleFilename);
   }
 
-  std::time_t getModuleTimestamp(StringRef ModuleFilename) override {
+  bool isMarkedUpToDate(StringRef ModuleFilename) override {
     std::string TimestampFilename =
         serialization::ModuleFile::getTimestampFilename(ModuleFilename);
     llvm::sys::fs::file_status Status;
     if (llvm::sys::fs::status(ModuleFilename, Status) != std::error_code{})
-      return 0;
-    return llvm::sys::toTimeT(Status.getLastModificationTime());
+      return false;
+    return llvm::sys::toTimeT(Status.getLastModificationTime()) >
+           BuildSessionTimestamp;
   }
 
-  void updateModuleTimestamp(StringRef ModuleFilename) override {
+  void markUpToDate(StringRef ModuleFilename) override {
     // Overwrite the timestamp file contents so that file's mtime changes.
     std::error_code EC;
     llvm::raw_fd_ostream OS(
@@ -62,6 +68,8 @@ public:
 };
 } // namespace
 
-IntrusiveRefCntPtr<ModuleCache> clang::createCrossProcessModuleCache() {
-  return llvm::makeIntrusiveRefCnt<CrossProcessModuleCache>();
+IntrusiveRefCntPtr<ModuleCache>
+clang::createCrossProcessModuleCache(std::time_t BuildSessionTimestamp) {
+  return llvm::makeIntrusiveRefCnt<CrossProcessModuleCache>(
+      BuildSessionTimestamp);
 }
diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index fa9533b..9fd7505 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -174,11 +174,11 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type,
   NewModule->Index = Chain.size();
   NewModule->FileName = FileName.str();
   NewModule->ImportLoc = ImportLoc;
-  NewModule->InputFilesValidationTimestamp = 0;
+  NewModule->InputFilesValidated = false;
 
   if (NewModule->Kind == MK_ImplicitModule)
-    NewModule->InputFilesValidationTimestamp =
-        ModCache->getModuleTimestamp(NewModule->FileName);
+    NewModule->InputFilesValidated =
+        ModCache->isMarkedUpToDate(NewModule->FileName);
 
   // Load the contents of the module
   if (std::unique_ptr<llvm::MemoryBuffer> Buffer = lookupBuffer(FileName)) {