[clang] [llvm] [llvm][NFC] Rework Timer.cpp globals to ensure valid lifetimes (PR #121663)

[via llvm-commits]

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@@ -115,22 +92,12 @@ std::unique_ptr<raw_ostream> llvm::CreateInfoOutputFile() {
   return std::make_unique<raw_fd_ostream>(2, false); // stderr.
 }
 
-namespace {
-struct CreateDefaultTimerGroup {
-  static void *call() {
-    return new TimerGroup("misc", "Miscellaneous Ungrouped Timers");
-  }
-};
-} // namespace
-static ManagedStatic<TimerGroup, CreateDefaultTimerGroup> DefaultTimerGroup;
-static TimerGroup *getDefaultTimerGroup() { return &*DefaultTimerGroup; }
-
 //===----------------------------------------------------------------------===//
 // Timer Implementation
 //===----------------------------------------------------------------------===//
 
 void Timer::init(StringRef TimerName, StringRef TimerDescription) {
-  init(TimerName, TimerDescription, *getDefaultTimerGroup());
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macurtis-amd wrote:

> Does the new mtg::DefaultTimerGroup() introduce extra overhead?
I didn't measure it, but i think at most it is the overhead of is a one or two function calls.

> I presume that the new code retains this mechanism
Yes. 

https://github.com/llvm/llvm-project/pull/121663