[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.

2 files changed, 9 insertions, 5 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 5a79fe0..eb8483d 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -829,9 +829,10 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
   AST->SourceMgr = new SourceManager(AST->getDiagnostics(),
                                      AST->getFileManager(),
                                      UserFilesAreVolatile);
-  AST->ModCache = createCrossProcessModuleCache();
   AST->HSOpts = std::make_unique<HeaderSearchOptions>(HSOpts);
   AST->HSOpts->ModuleFormat = std::string(PCHContainerRdr.getFormats().front());
+  AST->ModCache =
+      createCrossProcessModuleCache(AST->HSOpts->BuildSessionTimestamp);
   AST->HeaderInfo.reset(new HeaderSearch(AST->getHeaderSearchOpts(),
                                          AST->getSourceManager(),
                                          AST->getDiagnostics(),
@@ -1548,7 +1549,8 @@ ASTUnit::create(std::shared_ptr<CompilerInvocation> CI,
   AST->UserFilesAreVolatile = UserFilesAreVolatile;
   AST->SourceMgr = new SourceManager(AST->getDiagnostics(), *AST->FileMgr,
                                      UserFilesAreVolatile);
-  AST->ModCache = createCrossProcessModuleCache();
+  AST->ModCache = createCrossProcessModuleCache(
+      AST->Invocation->getHeaderSearchOpts().BuildSessionTimestamp);
 
   return AST;
 }
@@ -1834,7 +1836,6 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromCommandLine(
   AST->FileMgr = new FileManager(AST->FileSystemOpts, VFS);
   AST->StorePreamblesInMemory = StorePreamblesInMemory;
   AST->PreambleStoragePath = PreambleStoragePath;
-  AST->ModCache = createCrossProcessModuleCache();
   AST->OnlyLocalDecls = OnlyLocalDecls;
   AST->CaptureDiagnostics = CaptureDiagnostics;
   AST->TUKind = TUKind;
@@ -1843,6 +1844,8 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromCommandLine(
     = IncludeBriefCommentsInCodeCompletion;
   AST->UserFilesAreVolatile = UserFilesAreVolatile;
   AST->Invocation = CI;
+  AST->ModCache = createCrossProcessModuleCache(
+      AST->Invocation->getHeaderSearchOpts().BuildSessionTimestamp);
   AST->SkipFunctionBodies = SkipFunctionBodies;
   if (ForSerialization)
     AST->WriterData.reset(new ASTWriterData(*AST->ModCache));
@@ -2378,7 +2381,6 @@ bool ASTUnit::serialize(raw_ostream &OS) {
 
   SmallString<128> Buffer;
   llvm::BitstreamWriter Stream(Buffer);
-  IntrusiveRefCntPtr<ModuleCache> ModCache = createCrossProcessModuleCache();
   ASTWriter Writer(Stream, Buffer, *ModCache, {});
   return serializeUnit(Writer, Buffer, getSema(), OS);
 }
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 503d364..b3a23e6 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -72,7 +72,9 @@ CompilerInstance::CompilerInstance(
     ModuleCache *ModCache)
     : ModuleLoader(/*BuildingModule=*/ModCache),
       Invocation(std::move(Invocation)),
-      ModCache(ModCache ? ModCache : createCrossProcessModuleCache()),
+      ModCache(ModCache ? ModCache
+                        : createCrossProcessModuleCache(
+                              getHeaderSearchOpts().BuildSessionTimestamp)),
       ThePCHContainerOperations(std::move(PCHContainerOps)) {
   assert(this->Invocation && "Invocation must not be null");
 }