[Support] Add TimeTraceScope constructor without detail arg

This simplifies code where no extra details are required
Also don't write out detail when it is empty.

Differential Revision: https://reviews.llvm.org/D71347

clang/lib/CodeGen/BackendUtil.cpp

@@ -896,7 +896,7 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
 
   {
     PrettyStackTraceString CrashInfo("Per-function optimization");
-    llvm::TimeTraceScope TimeScope("PerFunctionPasses", StringRef(""));
+    llvm::TimeTraceScope TimeScope("PerFunctionPasses");
 
     PerFunctionPasses.doInitialization();
     for (Function &F : *TheModule)
@@ -907,13 +907,13 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
 
   {
     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);
   }
 
@@ -1499,7 +1499,7 @@ void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
                               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()) {

clang/lib/CodeGen/CodeGenAction.cpp

@@ -249,7 +249,7 @@ namespace clang {
 
     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;

clang/lib/Parse/ParseAST.cpp

@@ -151,7 +151,7 @@ void clang::ParseAST(Sema &S, bool PrintStats, bool SkipFunctionBodies) {
   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;

clang/lib/Sema/Sema.cpp

@@ -924,8 +924,7 @@ void Sema::ActOnEndOfTranslationUnitFragment(TUFragmentKind Kind) {
   }
 
   {
-    llvm::TimeTraceScope TimeScope("PerformPendingInstantiations",
-                                   StringRef(""));
+    llvm::TimeTraceScope TimeScope("PerformPendingInstantiations");
     PerformPendingInstantiations();
   }
 

clang/lib/Serialization/GlobalModuleIndex.cpp

@@ -134,7 +134,7 @@ GlobalModuleIndex::GlobalModuleIndex(std::unique_ptr<llvm::MemoryBuffer> Buffer,
                        "' 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;
@@ -770,7 +770,7 @@ bool GlobalModuleIndexBuilder::writeIndex(llvm::BitstreamWriter &Stream) {
   }
 
   using namespace llvm;
-  llvm::TimeTraceScope TimeScope("Module WriteIndex", StringRef(""));
+  llvm::TimeTraceScope TimeScope("Module WriteIndex");
 
   // Emit the file header.
   Stream.Emit((unsigned)'B', 8);

clang/tools/driver/cc1_main.cpp

@@ -246,7 +246,7 @@ int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
 
   // Execute the frontend actions.
   {
-    llvm::TimeTraceScope TimeScope("ExecuteCompiler", StringRef(""));
+    llvm::TimeTraceScope TimeScope("ExecuteCompiler");
     Success = ExecuteCompilerInvocation(Clang.get());
   }
 

llvm/include/llvm/Support/TimeProfiler.h

@@ -58,6 +58,10 @@ struct TimeTraceScope {
   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);

llvm/lib/Support/TimeProfiler.cpp

@@ -123,7 +123,9 @@ struct TimeTraceProfiler {
         J.attribute("ts", StartUs);
         J.attribute("dur", DurUs);
         J.attribute("name", E.Name);
-        J.attributeObject("args", [&] { J.attribute("detail", E.Detail); });
+        if (!E.Detail.empty()) {
+          J.attributeObject("args", [&] { J.attribute("detail", E.Detail); });
+        }
       });
     }