-ftime-report: Move FrontendTimer closer to TimeTraceScope

... to improve consistency and make "Clang time report" cover
`FrontendAction::BeginSourceFile` and `FrontendAction::EndSourceFile`.

Author: MaskRay

clang/include/clang/Frontend/CompilerInstance.h

@@ -632,8 +632,6 @@ class CompilerInstance : public ModuleLoader {
 
   llvm::TimerGroup &getTimerGroup() const { return *timerGroup; }
 
-  bool hasFrontendTimer() const { return (bool)FrontendTimer; }
-
   llvm::Timer &getFrontendTimer() const {
     assert(FrontendTimer && "Compiler instance has no frontend timer!");
     return *FrontendTimer;

clang/lib/Frontend/CompilerInstance.cpp

@@ -1038,9 +1038,6 @@ bool CompilerInstance::ExecuteAction(FrontendAction &Act) {
        << LLVM_VERSION_STRING << " default target "
        << llvm::sys::getDefaultTargetTriple() << "\n";
 
-  if (getCodeGenOpts().TimePasses)
-    createFrontendTimer();
-
   if (getFrontendOpts().ShowStats || !getFrontendOpts().StatsFile.empty())
     llvm::EnableStatistics(false);
 

clang/lib/Frontend/FrontendAction.cpp

@@ -1069,12 +1069,7 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
 llvm::Error FrontendAction::Execute() {
   CompilerInstance &CI = getCompilerInstance();
-
-  if (CI.hasFrontendTimer()) {
-    llvm::TimeRegion Timer(CI.getFrontendTimer());
-    ExecuteAction();
-  }
-  else ExecuteAction();
+  ExecuteAction();
 
   // If we are supposed to rebuild the global module index, do so now unless
   // there were any module-build failures.

clang/tools/driver/cc1_main.cpp

@@ -283,6 +283,10 @@ int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
   // Execute the frontend actions.
   {
     llvm::TimeTraceScope TimeScope("ExecuteCompiler");
+    bool TimePasses = Clang->getCodeGenOpts().TimePasses;
+    if (TimePasses)
+      Clang->createFrontendTimer();
+    llvm::TimeRegion Timer(TimePasses ? &Clang->getFrontendTimer() : nullptr);
     Success = ExecuteCompilerInvocation(Clang.get());
   }