Add TimeTraceScope constructor without detail arg to simplify code where no detail required

[russell.gallop]

Summary

Also don't write out detail when it is empty, which reduces size of generated traces.

[anton-afanasyev]

LGTM

clang/lib/CodeGen/BackendUtil.cpp

void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
   // Before executing passes, print the final values of the LLVM options.
   cl::PrintOptionValues();
 
   // Run passes. For now we do all passes at once, but eventually we
   // would like to have the option of streaming code generation.
 
   {
     PrettyStackTraceString CrashInfo("Per-function optimization");
-    llvm::TimeTraceScope TimeScope("PerFunctionPasses", StringRef(""));
+    llvm::TimeTraceScope TimeScope("PerFunctionPasses");
 
     PerFunctionPasses.doInitialization();
     for (Function &F : *TheModule)
       if (!F.isDeclaration())
         PerFunctionPasses.run(F);
     PerFunctionPasses.doFinalization();
   }
 
   {
     PrettyStackTraceString CrashInfo("Per-module optimization passes");
-    llvm::TimeTraceScope TimeScope("PerModulePasses", StringRef(""));
+    llvm::TimeTraceScope TimeScope("PerModulePasses");
     PerModulePasses.run(*TheModule);
   }
 
   {
     PrettyStackTraceString CrashInfo("Code generation");
-    llvm::TimeTraceScope TimeScope("CodeGenPasses", StringRef(""));
+    llvm::TimeTraceScope TimeScope("CodeGenPasses");
     CodeGenPasses.run(*TheModule);
   }
 
   if (ThinLinkOS)
     ThinLinkOS->keep();
   if (DwoOS)
     DwoOS->keep();
 }
void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
                               const HeaderSearchOptions &HeaderOpts,
                               const CodeGenOptions &CGOpts,
                               const clang::TargetOptions &TOpts,
                               const LangOptions &LOpts,
                               const llvm::DataLayout &TDesc, Module *M,
                               BackendAction Action,
                               std::unique_ptr<raw_pwrite_stream> OS) {
 
-  llvm::TimeTraceScope TimeScope("Backend", StringRef(""));
+  llvm::TimeTraceScope TimeScope("Backend");
 
   std::unique_ptr<llvm::Module> EmptyModule;
   if (!CGOpts.ThinLTOIndexFile.empty()) {
     // If we are performing a ThinLTO importing compile, load the function index
     // into memory and pass it into runThinLTOBackend, which will run the
     // function importer and invoke LTO passes.
     Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
         llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile,

clang/lib/CodeGen/CodeGenAction.cpp

bool LinkInModules() {
         if (Err)
           return true;
       }
       return false; // success
     }
 
     void HandleTranslationUnit(ASTContext &C) override {
       {
-        llvm::TimeTraceScope TimeScope("Frontend", StringRef(""));
+        llvm::TimeTraceScope TimeScope("Frontend");
         PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");
         if (FrontendTimesIsEnabled) {
           LLVMIRGenerationRefCount += 1;
           if (LLVMIRGenerationRefCount == 1)
             LLVMIRGeneration.startTimer();
         }
 
         Gen->HandleTranslationUnit(C);

clang/lib/Parse/ParseAST.cpp

if (External)
     External->StartTranslationUnit(Consumer);
 
   // If a PCH through header is specified that does not have an include in
   // the source, or a PCH is being created with #pragma hdrstop with nothing
   // after the pragma, there won't be any tokens or a Lexer.
   bool HaveLexer = S.getPreprocessor().getCurrentLexer();
 
   if (HaveLexer) {
-    llvm::TimeTraceScope TimeScope("Frontend", StringRef(""));
+    llvm::TimeTraceScope TimeScope("Frontend");
     P.Initialize();
     Parser::DeclGroupPtrTy ADecl;
     for (bool AtEOF = P.ParseFirstTopLevelDecl(ADecl); !AtEOF;
          AtEOF = P.ParseTopLevelDecl(ADecl)) {
       // If we got a null return and something *was* parsed, ignore it.  This
       // is due to a top-level semicolon, an action override, or a parse error
       // skipping something.
       if (ADecl && !Consumer->HandleTopLevelDecl(ADecl.get()))

clang/lib/Sema/Sema.cpp

if (ExternalSource) {
     for (auto PII : Pending)
       if (auto Func = dyn_cast<FunctionDecl>(PII.first))
         Func->setInstantiationIsPending(true);
     PendingInstantiations.insert(PendingInstantiations.begin(),
                                  Pending.begin(), Pending.end());
   }
 
   {
-    llvm::TimeTraceScope TimeScope("PerformPendingInstantiations",
-                                   StringRef(""));
+    llvm::TimeTraceScope TimeScope("PerformPendingInstantiations");
     PerformPendingInstantiations();
   }
 
   // Finalize analysis of OpenMP-specific constructs.
   if (LangOpts.OpenMP)
     finalizeOpenMPDelayedAnalysis();
 
   assert(LateParsedInstantiations.empty() &&

clang/lib/Serialization/GlobalModuleIndex.cpp

GlobalModuleIndex::GlobalModuleIndex(std::unique_ptr<llvm::MemoryBuffer> Buffer,
                                      llvm::BitstreamCursor Cursor)
     : Buffer(std::move(Buffer)), IdentifierIndex(), NumIdentifierLookups(),
       NumIdentifierLookupHits() {
   auto Fail = [&Buffer](llvm::Error &&Err) {
     report_fatal_error("Module index '" + Buffer->getBufferIdentifier() +
                        "' failed: " + toString(std::move(Err)));
   };
 
-  llvm::TimeTraceScope TimeScope("Module LoadIndex", StringRef(""));
+  llvm::TimeTraceScope TimeScope("Module LoadIndex");
   // Read the global index.
   bool InGlobalIndexBlock = false;
   bool Done = false;
   while (!Done) {
     llvm::BitstreamEntry Entry;
     if (Expected<llvm::BitstreamEntry> Res = Cursor.advance())
       Entry = Res.get();
     else
if (getModuleFileInfo(File).Signature) {
         return true;
     } else if (Info.StoredSize != File->getSize() ||
                Info.StoredModTime != File->getModificationTime())
       // Verify Size and ModTime.
       return true;
   }
 
   using namespace llvm;
-  llvm::TimeTraceScope TimeScope("Module WriteIndex", StringRef(""));
+  llvm::TimeTraceScope TimeScope("Module WriteIndex");
 
   // Emit the file header.
   Stream.Emit((unsigned)'B', 8);
   Stream.Emit((unsigned)'C', 8);
   Stream.Emit((unsigned)'G', 8);
   Stream.Emit((unsigned)'I', 8);
 
   // Write the block-info block, which describes the records in this bitcode

clang/tools/driver/cc1_main.cpp

llvm::install_fatal_error_handler(LLVMErrorHandler,
                                   static_cast<void*>(&Clang->getDiagnostics()));
 
   DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
   if (!Success)
     return 1;
 
   // Execute the frontend actions.
   {
-    llvm::TimeTraceScope TimeScope("ExecuteCompiler", StringRef(""));
+    llvm::TimeTraceScope TimeScope("ExecuteCompiler");
     Success = ExecuteCompilerInvocation(Clang.get());
   }
 
   // If any timers were active but haven't been destroyed yet, print their
   // results now.  This happens in -disable-free mode.
   llvm::TimerGroup::printAll(llvm::errs());
   llvm::TimerGroup::clearAll();
 

llvm/include/llvm/Support/TimeProfiler.h

 struct TimeTraceScope {
 
   TimeTraceScope() = delete;
   TimeTraceScope(const TimeTraceScope &) = delete;
   TimeTraceScope &operator=(const TimeTraceScope &) = delete;
   TimeTraceScope(TimeTraceScope &&) = delete;
   TimeTraceScope &operator=(TimeTraceScope &&) = delete;
 
+  TimeTraceScope(StringRef Name) {
+    if (TimeTraceProfilerInstance != nullptr)
+      timeTraceProfilerBegin(Name, StringRef(""));
+  }
   TimeTraceScope(StringRef Name, StringRef Detail) {
     if (TimeTraceProfilerInstance != nullptr)
       timeTraceProfilerBegin(Name, Detail);
   }
   TimeTraceScope(StringRef Name, llvm::function_ref<std::string()> Detail) {
     if (TimeTraceProfilerInstance != nullptr)
       timeTraceProfilerBegin(Name, Detail);
   }

llvm/lib/Support/TimeProfiler.cpp

for (const auto &E : Entries) {
 
       J.object([&]{
         J.attribute("pid", 1);
         J.attribute("tid", 0);
         J.attribute("ph", "X");
         J.attribute("ts", StartUs);
         J.attribute("dur", DurUs);
         J.attribute("name", E.Name);
+        if (!E.Detail.empty()) {
           J.attributeObject("args", [&] { J.attribute("detail", E.Detail); });
+        }
       });
     }
 
     // Emit totals by section name as additional "thread" events, sorted from
     // longest one.
     int Tid = 1;
     std::vector<NameAndCountAndDurationType> SortedTotals;
     SortedTotals.reserve(CountAndTotalPerName.size());