Serialization: Let ASTWriter return the signature of the written module.

NFC

llvm-svn: 248344

clang/include/clang/Serialization/ASTWriter.h

@@ -505,10 +505,9 @@ private:
                     llvm::DenseSet<Stmt *> &ParentStmts);
 
   void WriteBlockInfoBlock();
-  void WriteControlBlock(Preprocessor &PP, ASTContext &Context,
-                         StringRef isysroot, const std::string &OutputFile);
-  void WriteInputFiles(SourceManager &SourceMgr,
-                       HeaderSearchOptions &HSOpts,
+  uint64_t WriteControlBlock(Preprocessor &PP, ASTContext &Context,
+                             StringRef isysroot, const std::string &OutputFile);
+  void WriteInputFiles(SourceManager &SourceMgr, HeaderSearchOptions &HSOpts,
                        bool Modules);
   void WriteSourceManagerBlock(SourceManager &SourceMgr,
                                const Preprocessor &PP);
@@ -572,9 +571,9 @@ private:
   void WriteDecl(ASTContext &Context, Decl *D);
   void AddFunctionDefinition(const FunctionDecl *FD, RecordData &Record);
 
-  void WriteASTCore(Sema &SemaRef,
-                    StringRef isysroot, const std::string &OutputFile,
-                    Module *WritingModule);
+  uint64_t WriteASTCore(Sema &SemaRef,
+                        StringRef isysroot, const std::string &OutputFile,
+                        Module *WritingModule);
 
 public:
   /// \brief Create a new precompiled header writer that outputs to
@@ -600,10 +599,12 @@ public:
   /// \param isysroot if non-empty, write a relocatable file whose headers
   /// are relative to the given system root. If we're writing a module, its
   /// build directory will be used in preference to this if both are available.
-  void WriteAST(Sema &SemaRef,
-                const std::string &OutputFile,
-                Module *WritingModule, StringRef isysroot,
-                bool hasErrors = false);
+  ///
+  /// \return the module signature, which eventually will be a hash of
+  /// the module but currently is merely a random 32-bit number.
+  uint64_t WriteAST(Sema &SemaRef, const std::string &OutputFile,
+                    Module *WritingModule, StringRef isysroot,
+                    bool hasErrors = false);
 
   /// \brief Emit a token.
   void AddToken(const Token &Tok, RecordDataImpl &Record);

clang/lib/Serialization/ASTWriter.cpp

@@ -1166,9 +1166,12 @@ static ASTFileSignature getSignature() {
 }
 
 /// \brief Write the control block.
-void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
-                                  StringRef isysroot,
-                                  const std::string &OutputFile) {
+uint64_t ASTWriter::WriteControlBlock(Preprocessor &PP,
+                                      ASTContext &Context,
+                                      StringRef isysroot,
+                                      const std::string &OutputFile) {
+  ASTFileSignature Signature = 0;
+
   using namespace llvm;
   Stream.EnterSubblock(CONTROL_BLOCK_ID, 5);
   RecordData Record;
@@ -1201,7 +1204,8 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
     // is non-deterministic.
     // FIXME: Remove this when output is deterministic.
     if (Context.getLangOpts().ImplicitModules) {
-      RecordData::value_type Record[] = {getSignature()};
+      Signature = getSignature();
+      RecordData::value_type Record[] = {Signature};
       Stream.EmitRecord(SIGNATURE, Record);
     }
 
@@ -1468,6 +1472,7 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
                   PP.getHeaderSearchInfo().getHeaderSearchOpts(),
                   PP.getLangOpts().Modules);
   Stream.ExitBlock();
+  return Signature;
 }
 
 namespace  {
@@ -4012,12 +4017,11 @@ time_t ASTWriter::getTimestampForOutput(const FileEntry *E) const {
   return IncludeTimestamps ? E->getModificationTime() : 0;
 }
 
-void ASTWriter::WriteAST(Sema &SemaRef,
-                         const std::string &OutputFile,
-                         Module *WritingModule, StringRef isysroot,
-                         bool hasErrors) {
+uint64_t ASTWriter::WriteAST(Sema &SemaRef, const std::string &OutputFile,
+                             Module *WritingModule, StringRef isysroot,
+                             bool hasErrors) {
   WritingAST = true;
-  
+
   ASTHasCompilerErrors = hasErrors;
   
   // Emit the file header.
@@ -4031,13 +4035,15 @@ void ASTWriter::WriteAST(Sema &SemaRef,
   Context = &SemaRef.Context;
   PP = &SemaRef.PP;
   this->WritingModule = WritingModule;
-  WriteASTCore(SemaRef, isysroot, OutputFile, WritingModule);
+  ASTFileSignature Signature =
+      WriteASTCore(SemaRef, isysroot, OutputFile, WritingModule);
   Context = nullptr;
   PP = nullptr;
   this->WritingModule = nullptr;
   this->BaseDirectory.clear();
 
   WritingAST = false;
+  return Signature;
 }
 
 template<typename Vector>
@@ -4049,10 +4055,9 @@ static void AddLazyVectorDecls(ASTWriter &Writer, Vector &Vec,
   }
 }
 
-void ASTWriter::WriteASTCore(Sema &SemaRef,
-                             StringRef isysroot,
-                             const std::string &OutputFile, 
-                             Module *WritingModule) {
+uint64_t ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
+                                 const std::string &OutputFile,
+                                 Module *WritingModule) {
   using namespace llvm;
 
   bool isModule = WritingModule != nullptr;
@@ -4197,7 +4202,7 @@ void ASTWriter::WriteASTCore(Sema &SemaRef,
   }
 
   // Write the control block
-  WriteControlBlock(PP, Context, isysroot, OutputFile);
+  uint64_t Signature = WriteControlBlock(PP, Context, isysroot, OutputFile);
 
   // Write the remaining AST contents.
   Stream.EnterSubblock(AST_BLOCK_ID, 5);
@@ -4527,6 +4532,8 @@ void ASTWriter::WriteASTCore(Sema &SemaRef,
       NumStatements, NumMacros, NumLexicalDeclContexts, NumVisibleDeclContexts};
   Stream.EmitRecord(STATISTICS, Record);
   Stream.ExitBlock();
+
+  return Signature;
 }
 
 void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {